摘要:

AbstractFused silica is an evolutionary product of continuing efforts to improve our chromatographic capabilities. It offers the normal user new horizons in inertness, chromatographic reproducibility, ease of column installation, and possibilities in on‐column trapping. Since this writing, chemically bonded phases in several film thicknesses became available on fused silica columns, and these are especially well suited to on‐column injections. The use of fused silica syringe needles to inject directly onto fused silica columns seems particularly interesting. Evolution is, of course, a continuous process and it would appear that we can expect continuing developments in this exciting a

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe selectivity of a column system, S, defined by equation 28, includes a variation coefficient (β) of plate number with capacity ratio which has a large influence on the peak capacity, as shown in Fig. 18. Some typical chromatograms are given. In order to predict S for a column system from Kovat's Index, equations 40 and 41 are given to calculate the constant of the carbon number rule for squalane at different temperatures or for different stationary phases. The specific retention value of heptane on squalane at different temperatures can be calculated from equation 42. The nonpolarity index, defined by equation 43, was used to calculate the retention value of heptane on various stationary phases. In liquid chromatography, the order of elution may be reversed by changing the composition of the eluent on the same chemically bonded silica (manufactured in China). The linear relations between the log retention values of different kinds of solutes or of a single solute on the silicas of different surface areas when using the same eluent are given

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThree main problems have to be solved in process gas chromatography: psychological, technical and economic.A simple concept already used with success for fifteen years by the author, called the Deferred Standard, is an answer for process GC and, to some extent, laboratory GC as well.That the injection of a pure compound in each analytical sequence is reproducible demonstrates the good working order of PGC. Accurate quantitative results may be obtained because the gas density balance is used as a calibrator detector for determining the relative response factors of the components of interest with respect to the Deferred Standard.By suppressing any calibration standards in process and laboratory chromatography, the Deferred Standard may reveal itself as a time and money saving technique.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractUnequal elution of sample components of different volatility out of the syringe needle is one of the major causes for discrimination occuring during the injection, i.e. the phenomena which results in peak areas for the high boiling compounds which are too small compared with the volatiles. This problem, associated with all vaporizing injectors that are used with syringes, can be minimized by careful choice of the needle handling technique. Various methods are compared experimentally. The “solvent flush” method is discussed in detail and demonstrated to be ineffective for reducing losses in the syringe needle. The “hot needle” technique, where the empty needle is preheated in the injector before pushing the plunger, was found to be superior or equal to an improved “solvent flush” method (which included preheating the needle and omitting the air plug between sample and flushing solvent. Generally it was found that the discrimination due to the syringe needle was reduced for larger sample volumes, although no further changes were noticed when these exceeded

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractModern liquid chromatographic (LC) conditions which effect a separation of polycyclic aromatic hydrocarbons (PAH) containing up to ten rings are described. The LC conditions include reverse‐phase chromatographic columns in combination with a quaternary solvent system. Methanol and water are combined to form solvent system A, while tetrahydrofuran and acetonitrile form solvent system B. Solvent systems A and B are then combined in a linear gradient relationship to effect the separation. The separation of benzo(a)pyrene and perylene along with benzo(ghi)perylene and indeno (1,2,3‐cd)pyrene is achieved. In the same chromatogram the PAHs, coronene, dibenzo(a,e), (a,i), (a,h)pyrene and tribenzo(a,e,i)pyrene are also separated. An increase in column temperature from 45°C to 55°C is shown to shorten the elution time and increase chromatographic resolution of many of the PAHs examined. At least 25 PAHs ranging in molecular weight from 178 to 536 are examined for their chromatographic behavior. As examples, the application of this method to samples from a coal liquefication process are included. The samples are examined with both a UV detector and fluouescence detector to demonstrate the utility of dual detectors when analyzing for PAHs in complex matrices. With minor modification of the gradient this method is applicable to PAHs containing ring systems other than those reported

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240031211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY