摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700071

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic.This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm.up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation.Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity.CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C.of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view.Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned.Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium.Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms.of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view.Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium.Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C.of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700072

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic.This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm.up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation.Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity.CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C.of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view.Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned.Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium.Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms.of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view.Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium.Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C.of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700079

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic.This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm.up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation.Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity.CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C.of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view.Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned.Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium.Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms.of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view.Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium.Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C.of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms.give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation.Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium.Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm.up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes.Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium.Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700085

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700094

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700095

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700096

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic.This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700097

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic.This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700099

出版商:RSC    

年代:1932

数据来源: RSC

摘要:

294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected.The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results.The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable.The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm.Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected.Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm.in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic.This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm.of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity. CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased.The best conditions for the detection of calcium were found to be as follows: Take 50 C.C. of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm.up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation.Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.294 EVERS: THE DETECTION OF SMALL QUANTITIES OF CALCIUM Adding 5 mgrms. of calcium. Added salts. Result. No added salt. Immediate pptn. Sodium chloride, 1 grm. Borax, 1 grm. Sodium potassium tartrate, 1 grm. Potassium citrate, 1 grm. Variations in the concentration of the reagents did not appreciably improve matters. It was found that even 0.25 grm. of potassium citrate in 60 C.C. of solution prevented the precipitation of 2 mgrms. of calcium. Further complications would be introduced if magnesium were also present in the salt as an impurity.CALCIUM OLEATE TEsT.-The formation of an opalescence on the addition of sodium oleate solution to a solution is an extremely delicate test for calcium. Under the best conditions 0.01 mgrm. of calcium in 50 C.C. of solution, or 0.00002 per cent., can just be detected. The test is also, of course, a test for magnesium, but is much less sensitive, 0-6 mgrm. in 50 C.C. of solution, or 0-0012 per cent., being the minimum quantity which can be detected. Further, within certain limits of concentration the pre- cipitation of magnesium is entirely suppressed in the presence of potassium citrate, whilst the sensitiveness of the calcium test is actually increased. The best conditions for the detection of calcium were found to be as follows: Take 50 C.C.of the solution containing calcium, which should be neutral or slightly alkaline. Dissolve in it 2 grms. of potassium citrate, and add 0-3 C.C. of a solution prepared by dissolving 10 grms. of oleic acid in 200 C.C. of 1 per cent. sodium hydroxide. A certain excess of alkali is desirable for the best results. The test is only satisfactory between certain limits of calcium concentration. With quantities exceeding 1 mgrm. in 60 C.C. the opalescence is actually reduced. Under the above conditions quantities of mag- nesium up to 15 mgrms. give no opalescence. Summarising the results, the oleate test is excellent for quantities of calcium varying from 0-01 mgrm. up to 1 mgrm. in the absence of more than 10 mgrms. of magnesium, and within these limits in the absence of other salts the opalescence appears proportional to the calcium present. Further experiments showed, however, that, in spite of its delicacy, the oleate test is not suitable for the purpose in view. Possibly, if the test could be carried out, using standards containing the same concentration of the same salt, it would be satisfactory, but this is hardly practicable. The addition of other salts, even in the absence of potassium citrate, caused the results to be erratic. This was partly due to their “salting out ” effect on the soap, which sometimes caused flocculation, but this was not the whole explanation. Almost immediate pptn. Slight ppt. after 30 minutes. Slight ppt. after 30 minutes. No ppt. This line of investigation was therefore abandoned. Mix and allow the mixture to stand. An excess of the reagent gives less opalescence.

ISSN:0003-2654    

DOI:10.1039/AN9325700101

出版商:RSC    

年代:1932

数据来源: RSC