ISSN:0003-2654    

DOI:10.1039/AN96186FX009

出版商:RSC    

年代:1961

数据来源: RSC

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492 PUBLICATIONS RECEIVED FEBRUARY (1961) ISSUE, p. 113, 13th line under “Reagents.” MARCH (1962) ISSUE, p. 200, 28th and 29th lines (the acknowledgments). For “Ammonia solution, 50 per cent. w/v” read “Ammonia solzttion-Ammonia solution, sp. gr. 0.880, diluted (1 + l).” Delete all words after ‘‘Note. ’ ’492 PUBLICATIONS RECEIVED FEBRUARY (1961) ISSUE, p. 113, 13th line under “Reagents.” MARCH (1962) ISSUE, p. 200, 28th and 29th lines (the acknowledgments). For “Ammonia solution, 50 per cent. w/v” read “Ammonia solzttion-Ammonia solution, sp. gr. 0.880, diluted (1 + l).” Delete all words after ‘‘Note. ’ ’492 PUBLICATIONS RECEIVED FEBRUARY (1961) ISSUE, p. 113, 13th line under “Reagents.” MARCH (1962) ISSUE, p. 200, 28th and 29th lines (the acknowledgments). For “Ammonia solution, 50 per cent. w/v” read “Ammonia solzttion-Ammonia solution, sp. gr. 0.880, diluted (1 + l).” Delete all words after ‘‘Note. ’ ’492 PUBLICATIONS RECEIVED FEBRUARY (1961) ISSUE, p. 113, 13th line under “Reagents.” MARCH (1962) ISSUE, p. 200, 28th and 29th lines (the acknowledgments). For “Ammonia solution, 50 per cent. w/v” read “Ammonia solzttion-Ammonia solution, sp. gr. 0.880, diluted (1 + l).” Delete all words after ‘‘Note. ’ ’

ISSN:0003-2654    

DOI:10.1039/AN961860X011

出版商:RSC    

年代:1961

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN96186BX015

出版商:RSC    

年代:1961

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN96186FP049

出版商:RSC    

年代:1961

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN96186BP059

出版商:RSC    

年代:1961

数据来源: RSC

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MARCH, 1961 Vol. 86, No. I020 THE ANALYST PROCEEDINGS OF THE SOCIETY FOR ANALYTICAL CHEMISTRY NEW MEMBERS ORDINARY MEMBERS Michael John Bowley, BSc. (Bris.) ; Thomas Arthur Brock, B.Sc. (Lond.), F.R.I.C., A.F.Inst.Pet.; Roy George Clark, B.Sc. (Lond.), A.R.I.C. ; Ronald Maurice Cooper, M.Sc. (Lond.) ; Edwin Fletcher; Joan Meakin, B.Sc. (Lond.) ; Frend John Miner, B.A. (Colorado), M.S., Ph.D. (Oregon) ; Howard Antrobus Moule, B.Sc. (Lond.), A.R.I.C. ; Howard Alfred Nicholls, A.R.I.C. ; Kenneth Charles Nutt, B.Sc. (Lond.) ; John Wilson Ogleby, B.Sc. (Dunelm.) ; Joseph Howard Oldfield, F.R.I.C. ; Ernest Walter Peacock, BSc. (Lond.) ; Richard Redvers Scott, B.A. (Cantab.) ; Brian William Stannard, B.Sc. (Lon.), A.R.I.C. ; Bernard Thomas Dudley Sully, B.Sc., Ph.D. (Lond.) , A.R.C.S., F.R.I.C.JUNIOR MEMBERS Montague John Giles; Margaret Davidson Macuean, B.Sc. (Glas.) ; John Lawrence Roberts ; Sydney Williams. DEATH David George Allen Geoffrey Alfred Bracewell Donald Ford Phillips. WE record with regret the death of NORTH OF ENGLAND SECTION THE thirty-sixth Annual General Meeting of the Section was held at 2.15 p.m on Saturday, January 28th, 1961, at the “Nag’s Head Hotel,” Lloyd Street, Manchester. The Chairman of the Section, Dr. J. R. Edisbury, presided. The following appointments were made for the ensuing year :-Chairman-Mr. J. Markland. Vice-Chairman-Mr. C. J. House. Hon. Secretary and Treasurer-Mr. B. Hulme, Ch. Goldrei, Foucard & Son Ltd., Brookfield Drive, Liverpool, 9. Members of Committee-Mr. R. Butler, Mr. G. B. Crump, Dr. W.Cule Davies, Mr. A. 0. Jones, Mr. G. F. Longman and Mr. R. Sinar. Mr. A. A. D. Comrie and Mr. F. Dixon were appointed Hon. Auditors. The Annual General Meeting was followed by an Ordinary Meeting of the Section, when Dr. J. R. Edisbury gave his Retiring Chairman’s Address. The Chair at this meeting was taken by the new Chairman of the Section, Mr. J. Markland, B.Sc., F.R.I.C. 145146 PROCEEDINGS p o l . 86 SCOTTISH SECTION THE twenty-sixth Annual General Meeting of the Section was held at 6.30 p.m. on Thursday, January 26th, 1961, a t the Grosvenor Restaurant, 72 Gordon Street, Glasgow, C.l. The Chair was taken by the Chairman of the Section, Mr. A. N. Harrow, A.H.-W.C., F.R.I.C. The following office bearers were elected for the forthcoming year :-Chairman-Mr.A. F. Williams. Vice-Chairman-Dr. R. A. Chalmers. Hun. Secretary and Treasurer-Mr. J. Brooks, Research and Development Department, Imperial Chemical Industries Ltd., Nobel Division, Stevenston, Ayrshire. Members of Comvnittee-Dr. F. J. Elliott, Mr. J, K. McLellan, Mr. H. C. Moir, Mr. J. W. Murfin and Mr. S. C. Sloan. Mr. C. B. Hackett and Mr. W. J. Murray were re-appointed Hon. Auditors. The Annual General Meeting was followed by an Ordinary Meeting of the Section, at which the Chair was taken by the retiring Ch,airman of the Section, Mr. A. N. Harrow, A.H.-W.C., F.R.I.C. The following paper was presented: “Chemical Research in the Electricity Supply Industry,” by J. M. Ward, B.Sc., F.R.I.C. MICROCHEMISTRY GROUP THE twenty-eighth London Discussion Meeting of the Group was held at 6.30 p.m. on Wednes- day, January 25th, 1961, at “The Feathers,” Tudor Street, London, E.C.4. The Chair was taken by the Vice-chairman of the Group, Mr. C. Whalley, BSc., F.R.I.C. A discussion on “Hydrogenation Methods in Microanalysis’’ was opened by R. A. D. Smith.

ISSN:0003-2654    

DOI:10.1039/AN9618600145

出版商:RSC    

年代:1961

数据来源: RSC

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146 PROCEEDINGS p o l . 86 Obituary HUBERT THOMAS STANLEY BRITTON HUBERT THOMAS STANLEY BRITTON died at the early age of 68 on December 30th, 1960, after a brief illness. His death is a grievous loss to analytical chemistry, the more SO since he leaves much unpublished work, which it had been his intention to write up during his retirement. Born a t Kingswood, near Bristol, on April 22nd, 1892, the son of a shoemaker, he was educated at St. George’s Grammar School and the Merchant Venturers’ College. His entry on a scholarship to Bristol University in 1911 was almost prevented by the unfortunate death of his father in an accident, but the crisis was averted by the generosity of the people of his village, a kindness of which Britton often spoke. After graduation in 1914 and a short spell of schoolrnastering, he was posted to the Aeronautics Inspection Department, and served, mostly in Wolverhampton, for the duration of the war.In 1920 he became an assistant lecturer at King’s College, London, where he blegan the researches that led to the awards of D.Sc. (London) in 1926 and D.Sc. (Bristol) in 1934. He published eighteen papers before leaving to take up a senior D.S.I.R. award a t Imperial College in 1925. On the termination of the award he suffered considerable hardship, having then a young family, through several months of unemployment. During this time he wrote a number of articles for the technical press: these later formed the basis of his “Hydrogen Ions.” After a year as lecturer at Norwood Technical College, Britton moved in 1929 to the then University College of the South-West, where he remained, first as lecturer and later, from 1935, as professor, until his retirement in 1957 with the title of Professor Elmeritus in the University of Exeter.Britton’s researches started with an interest in beryllium, including a very sound appraisal of its analytical chemistry (Analyst, 1921, 46, 359, 437; 1922,47, 50), moved through phase studies with beryllium and chromium compounds, and quickly settled on a long series of studies by electrometric methods of homogeneous and heterogeneous ionic equilibria. These embraced hydrolytic precipitation (16 papers) complex acids (15 papers), complexation reactions involving weak acids (17 papers), and many other shorter series and individual papers of direct fundamental analytical interest.Very many of the physico-chemical constants emanating He is survived by his son and daughter.March, 19611 PROCEEDINGS 147 from his laboratory remain unchallenged today. The work on hydrolysis and complexation, of which Britton has himself left some connected account (Annual Reports of the Chemical Society, 1943, 40, 43), has undoubtedly paved the way to the modern unified concept of complexation reactions, which includes hydrolysis, acid - base ionisation and precipitation reactions. The bulk of this was published in the decade 1925 to 1935, and work of such difficulty and complexity required not only a very clear and wide vision, but also courage of no common order in the essay. Polymeric species such as Be,(OH),2+ were clearly in his thoughts 40 years ago, and one has only to consult modern tables of stability constants to find witness to his wisdom.Although he was much more interested in the fundamental data they would yield than in the origination of new devices, and he did not discover any new electrode systems, he was nevertheless very early in the field, and made extensive and significant contributions to the use and improvement of the hydrogen, oxygen, antimony, tungsten and glass electrodes. Conductometry was in early requisition in his work, and he pioneered the use of optical rotation in titrimetry. He had considerable interest in precipitimetric and redox titrimetry, and made important contributions to such widely diverse fields as chromium plating and the recovery of magnesium from sea water, and served on the B.S.I.committee on the standardisation of pH scales. Nearly 100 papers stand witness to his industry, with material for half as many again yet unpublished. The Britton - Robinson universal buffer is known to all, while within the covers of “Hydrogen Ions,” the fourth edition of which he completed just before he retired, is to be found a wealth of information such as can seldom be encompassed in such a work, and all of it bearing the stamp of intimate personal acquain- tance. For many years to come the two volumes of this book will remain indispensable in all laboratories concerned with pH and the physical chemistry of ionic solutions. During his early years a t Exeter, Britton was charged with the whole of the teaching and laboratory supervision for the Honours Degree, yet he contrived to produce “Conductometric Analysis” and the second edition of “Hydrogen Ions,” to be at his most active in research, to direct the work of a research assistant and many research students, and to do much extra- mural lecturing.This prodigious industry was characteristic of the man and continued during his tenure of the Chair. He was very active on Senate, and during the war years undertook the onerous duties of Dean of the Faculty of Science, besides serving as Senior Gas Adviser for Devon and Cornwall, acting as host to evacuated departments from London, and lecturing extensively to the Forces in the area. Subsequently he was drawn more and more from the bench and library by the demands of an expanding department, by preparations for the elevation of the College to University status and by the preliminary planning of a new building for the department.He continued vigorously to direct research, was instrumental in securing the formation of local sections of the Royal Institute of Chemistry and the Society of Chemical Industry, continued his forensic and extra-mural work, served on the Councils of our three sister Societies, and served as Chairman of Governors of the North Devon Technical College during a critical period. Britton was a man whom to know was to like and respect. He was outstandingly human, warmhearted and friendly. A flavour of the sceptic and the rebel added piquancy to his character. Always accessible, his advice, encouragement and help were freely given to student and colleague alike, and were as freely sought and highly valued. His lively personality was demonstrated in his animated, entertaining and stimulating lectures, both to undergraduates and to audiences in the depth of the country. Ever interested in his fellow men and in affairs and with a fund of both sage and amusing reminiscences, he was a sympathetic and enlivening companion. His brief retirement was sadly clouded by anxiety over the health of his wife and by her death in 1959. Britton’s sudden death was a great shock to all who knew him, particularly as he retained, outwardly at least, his full vigour and health until his final short illness, and the loss is made the greater by his inability to accomplish his objective of publishing the remainder of his work. He will long remain in the affectionate memory of the many students who passed through his hands and of all those who worked with him. E. BISHOP

ISSN:0003-2654    

DOI:10.1039/AN9618600146

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

148 CHILWELL AND HARTLEY : DETERMINATION OF RESIDUAL [Vol. 86 Determination of Residual Organo-phosphorus Insecticides inL Foodstuffs A Review* BY E. D. CHILWELL AND G. S. HARTLEY (Fisons Pest Control Ltd., Chesterford Park Research Station, nr. Saffron Walden, Essex) SUMMARY OF CONTENTS I. Introduction 11. Extraction of the insecticide 111. Clean-up procedure IV. Methods for the determination of organo-phosphorus insecticides V. Methods for individual compounds Demeton Demeton-methyl Dimefox Dipterex (trichlorphon) Diazinon Dimethoate Delnav Gusathion (guthion) Malathion Parathion Parathion-methyl, Chlorthion and EPN Phenkapton Phosdrin Phosphamidon Schradan Trithion Thimet (phorate) I. INTRODUCTION THE increasing use of toxic pesticides in agriculture has led to increasing awareness in government and medical circles of the problem of safe-guarding the consumer.Many countries, including the United States of America and the U.S.S.R., have introduced rigid legislation requiring detailed examination of a l l aspects of the potential hazard before new insecticides can be approved for specific usages. At the stage of enquiry and for purposes of implementing legislation, analytical methods are needed for determining residual con- tamination of foodstuffs, often in such trace amounts as to present a major technical problem for the analyst. The need for methods of determining residues is not confined to organo-phosphorus compounds, but, for several reasons, it came into prominence along with their development. First, these compounds are similar in chemical structure and mode of action to compounds developed for chemical warfare and therefore are of notoriously high toxicity to mammals.Secondly, the first widely used non-phosphorus synthetic insecticides, DDT and hexachloro- cyclohexane (BHC) were brought into use in the latter stages of the second World War, when investigation of minor hazards to the civilian population could not command a very high priority, and, being of low acute toxicity, they were accepted and established before much attention was paid to effects of prolonged low-level ingestion. Thirdly, they include the first organic systemic insecticides, capable of migration in the transport system of living plants; such compounds were naturally held to constitute a greater danger than those remaining on the external surfaces.It is in fact not necessarily true that systemic insecticides are more persistent than superficial ones, because the latter can to a large extent be dissolved in the leaf cuticle where they are resistant to aqueous washing, whereas the former, though inaccessible to washing, are in closer contact with the more chemically active plant tissues and so more subject to chemical destruction. * Reprints of this paper will be available shortly. For details, please see p. 207.March, 1961 J ORGANO-PHOSPHORUS INSECTICIDES IN FOODSTUFFS. A REVIEW 149 Sections I11 and IV of this review are largely relevant only to organo-phosphorus com- pounds, but so much of what we have to say in section 11, dealing with extraction procedures, is of general validity that it has been considered advisable in this section to draw on the literature of extraction generally.The procedures for determining residues are largely dictated by the technical problems involved. Such problems differ in the requirements of (1) the manufacturer of a new pesticide chemical called upon to submit evidence on the safety of his product to the consumer, (2) the analyst called upon to decide whether or not a sample of foodstuff contains a residue of a particular insecticide in excess of a given limit and (3) the public analyst who is asked if a foodstuff of unknown history contains an undesirable amount of any insecticide residue. The requirements of residue analysis for clearance under the Voluntary Notification Scheme in the United Kingdom have been described1; they are the determination of the amount of the chemical applied and of any toxic derivative of that chemical remaining in the crop at harvest. The research analyst is usually, or ideally, concerned with the organisation of experiments to prove the amount and nature of the residue present.At all times he is confident that no other insecticide could be present in the samples examined, and untreated samples of the crop are available. Methods do not need to be specific; in fact methods of broader spectrum are desirable because they are more likely to include metabolites of the chemical applied. The methods available at this stage can include many that are not practicable for the analyst concerned with a commercial crop.The use of radio-labelled insecticides permits a fuller examination of the errors in a final procedure than is possible by classical chemical methods. Their use is particularly valuable in the more biochemical aspects of the investigation, such as identifying products derived by plant chemistry. The second problem is that of the analyst required to determine accurately a named chemical in a foodstuff and certify that the amount present does not exceed a given limit. This need is for recognised standard methods of analysis that have been proved accurate by collaborative investigation in a number of different laboratories. Such collaborative examinations of promising methods are carried out by the Association of Official Agricultural Chemists in North America and by joint sub-committees of Government Departments, Industry and the Society for Analytical Chemistry in this country.The problem of the analyst presented with a sample of a foodstuff to examine for any possible insecticide residue is much more difficult. There is no close relation between amount present and consumer hazard unless the insecticide is known. Therefore, in the absence of knowledge of the insecticides present, the result would have to be interpreted as though the whole contamination were due to the most toxic insecticide in use. This would lead to unjustifiable condemnation of products in fact safely consumable. The problem could only be met in the chemical laboratory by working out some quick scheme of qualitative analysis to be applied before proceeding to quantitative assessment.The only serious attention yet given to this aspect of the subject is the possibility of identification in two- dimensional paper chromatograms,2 so far most completely worked out for chlorinated hydrocarbons. An alternative solution would be a method of determination in which “toxicity” is directly measured-Le., a bioassay-and a Sub-committee of the Analytical Methods Com- mittee of the Society for Analytical Chemistry is at present considering the practicability of this. The proposal meets several difficulties. First, analytical laboratories are not usually equipped for such methods. Secondly, they are expensive if mammals are used, or, if insects are used, the results are not necessarily more significant than those from a general chemical method, since it is an obvious and desirable tendency in research into new insecticides to bring forward those with the highest ratio of insect to mammalian toxicity.Lastly, the analyst is not usually called upon to find an amount of insecticide constituting a serious risk of death to the consumer, but rather for an amount that might produce marginal ill-health. He must therefore concentrate the insecticide so that acute toxicity can be demonstrated, without concentrating a t the same time any natural toxicants, or he must use some physiological response well short of death. The former demands knowledge of the insecticides present and does not therefore use the potential advantage of bioassay. The latter is perhaps possible at present for organo-phosphorus compounds, owing to their producing measurable reduction in blood cholinesterase level long before clinical symptoms are discernible. Feeding tests on mammals, with maximal amounts of the product, and150 CHILWELL AND HARTLEY : DETERMINATION OF RESIDUAL [Vol.86 determining blood cholinesterase might provide an answer to the general question “is there any significant contamination by any organo-phosphorus compound ? ” The method will, however, probably always be considered too lengthy to meet the requirements for clearance of perishable foodstuffs. A half-way stage between bioassay and chemical determination is assessment of cholin- esterase inactivation in vitro. The enzyme is readily accessible and its hydrolysis gives rise to easily measured acid.Applied to residue analysis the method is not particularly satis- factory for those compounds (the extreme example of which is schradan) that do not inhibit the enzyme in vitro, but only after conversion in the tissues of the animal. Again, if used after a broad method of separation, it is subject to interference by those natural products (not very widespread) that also inactivate the enzyme or by natural esters that can increase the acid liberated by the not very specific enzyme. To date, in fact, no satisfactory solution has been found to the problem of devising a method at once non-specific, reliable and significant. 11. EXTRACTION OF THE INSECTICIDE Before the residual insecticide can be subjected to a selective concentration process that isolates it adequately for the method of determination to be used, it must be extracted from the vegetable tissue into a convenient form of matter.This is almost always a solution in water or organic solvent, but occasionally processes approximating to direct distillation have been used. The extraction procedure is desirably itself selective to some extent, when this is con- sistent with its being adequately complete. Thus, stable and almost water-insoluble insecti- cides, particularly when crystalline, do not penetrate deeply into the aqueous internal tissues of plants, although they may diffuse into the swellable polymeric cuticle substance and the more oily of the soluble associated substances. The residue can then be mostly extracted by a short period of washing of the intact plant or fruit in an effective organic solvent, a process usually referred to as stripping. I t is not safe to assume that a short period of washing is adequate, nor that a treatment found adequate for leaves or fruits of one species is adequate for another, since there is great variation in cuticle thickness and composition. Experimental proof of adequate extraction must always be obtained (see below).Surface extraction procedure on more or less intact plant organs is desirable, when applicable, because the inclusion in the extract of large amounts of internal plant compounds that may have interfering properties is largely avoided. Such interference may be chemical, in the final process of determination, or physical, in that troublesome emulsions or precipi- tations may arise during the “clean-up” procedure.Washing procedures can be more or less drastic and deep-searching in their action, according to the solvent chosen and the state of the plant tissues. Washing of fresh intact leaves in hydrocarbon solvents removes little of the naturally occurring soluble substances except those found on or in the cuticle, even when carried on for periods of several hours. If the leaves are considerably desiccated before being washed or if washing of fresh leaves is carried out with a water-soluble solvent, much more material is dissolved from within the tissues, presumably because the various membrane barriers lose their resistance when their texture is altered by removal of water. Extraction with hot alcohol in a Soxhlet apparatus will eventually remove practically everything (except the skeletal substances, but the product of such extraction necessitates troublesome cleaning up.When extraction from within the tissues is necessary, the vegetable material is generally reduced to a fine “brei” by violent mechanical agitation in a Waring Blendor or similar machine. If the insecticide to be extracted is reasonably soluble in water (and deep penetra- tion in the tissues does not occur unless it is), maceration is usually carried out in water and the insecticide extracted from the water by a more suitable, and only incompletely miscible, solvent, usually chloroform. The extraction is best carried out after filtration, as the emulsions then formed are less intractable and can usually be broken by centrifugation.Sometimes, however, maceration directly in an organic solvent is preferred; for example Jones and Riddick3 macerate plant tissue with hexane and extract the hexane filtrate with acetonitrile. A procedure that has much to commend it aims at complete extraction of soluble small- molecule substances while largely avoiding the physically troublesome semi-solid and colloidal constituents. Chopped, but not macerated, tissue is extracted with a good, but not water-March, 19611 ORGAWO-PHOSPHORUS INSECTICIDES IN FOODSTUFFS. A REVIEW 151 miscible, solvent-e.g.? benzene or chloroform-in the presence of a desiccating agent-e.g., anhydrous sodium sulphate. The restricted permeability of most membranes is lost by the desiccation and more direct contact of fatty globules and solvent permitted, but the reduced mechanical damage as compared with maceration restricts the passage of solid debris into the extractant.The tissue itself in fact acts as a filter. The dessicant and chopped tissue are mixed in a column and slowly percolated.* The proof of complete extraction is not easy, but is an essential step in making sure that the whole procedure gives a significant result. (1) Carrying out extractions for different periods of time, it being assumed in inter- preting the results that complete extraction is obtained when not appreciably more is extracted by a longer process. (2) Comparing the proposed method of extraction with one assumed to be complete ---such as exhaustive extraction with hot alcohol in a Soxhlet apparatus.(3) Quantitative introduction of insecticide, preferably carrying a radio label, by the “cut stalk’’ technique if systemic or by painting on if non-systemic, and comparing the amount extracted with that applied. Step (1) would be invalidated if a proportion of insecticide is located in cells from which extraction is difficult, although most of it is easily accessible. When cold hydrocarbon solvents are used to extract natural waxes and fats from turgid leaves, the extracuticular matter is completely dissolved in a few minutes (mostly in seconds). Unpublished work in our laboratories has shown that a subsequent enormous slowing down is not evidence of complete extraction. A further similar amount of hydro- carbon-soluble substances is obtained when water is removed.The substances here are qualitatively different, but an extraneous substance, which had been allowed time to distribute, would doubtless show similar behaviour. There is a possible error in the opposite sense in step (2), since such drastic extraction may decompose a significant amount of the insecticide. Among the organo-phosphorus compounds, probably only schradan is sufficiently stable for this not to occur. In step (3), rapid determination is necessary unless so much decomposition is to be allowed that a quantitative balance cannot be expe~ted.~ With rapid determination, a good balance cannot be taken as evidential because there has not been time for the insecticide to move out of the accessible sites of application into less accessible sites. Step (1) at least should always be carried out, but additional confirmation is desirable.This is best obtained by animal feeding experiments run side by side with the proposed analysis.6 These give a direct check on the significance of the results for the purpose for which they are obtained. Not only does a successful check in this way rule out the possi- bility of insecticide being occluded in a form inaccessible to extraction but released by digestive processes, but it also checks the possible occurrence of toxic derivatives of the insecticide, produced by plant chemistry, that may not be recorded by the method of analysis. Ideally, such parallel feeding tests should be of the long-period low-level type, since, to obtain an acute response, a degree of contamination may be needed for which the analysis might be more efficient than at the low levels at which it will be used in practice.The conclusion to be desired is that no physiological damage can be found after consumption for a sufficient period of vegetable product in which the analytical method can still detect insecticide. For reasons of practicability and economy of effort it may be necessary to build up this answer from several lines of evidence, such as parallel analytical and feeding trials at high l e ~ e l , ~ , ~ together with feeding trials in which toxicant is added quantitatively at both high and low levels. A large factor of safety is always to be included in any recommendations made by responsible authorities. Steps taken for such proof are- None of these is free from objection.111. CLEAN-UP PROCEDURE The refinement necessary in cleaning up the extract from possibly interfering substances before the determination obviously depends on several factors, including the sensitivity and selectivity of the final procedure, the nature of crop or product and the lowest level of insecticide that must with certainty be detected. The necessity of distinguishing between insecticides, or between the original insecticide and some toxic derivatives thereof, may also influence the choice.162 CHILWELL AND HARTLEY: DETERMINATION OF RESIDUAL [Vol. 86 At present, no organo-phosphorus insecticide of strongly electrolytic nature is in use. Amiton exists mainly as a cation at the pH of plant tissues, but its ionisation is suppressed at higher pH values.Demeton-methyl can give rise to a fairly stable sulphonium salt, which is toxic by injection, but not particularly toxic by inge~tion.~ Products are formed by partial hydrolysis having a free acidic function on the phosphorus, but, once this stage has been reached, the molecule is no longer toxic. All organo-phosphorus insecticides so far are, in non-ionic form, favourably partitioned into chloroform from water, owing to exceptionally strong molecular forces between P -+ 0 and CHC1, or to the corresponding P +S cornpounds having much reduced hydrophilic behaviour. The least favourably partitioned of the insecticides in use is schradan, which still partitions 7 to 1 in favour of chloroform. ]Derivatives produced in the plant, which are generally oxidation products, are more favourable to water, that from dimethoate for example partitioning about 1 to 1.More exhaustive extraction with chloroform is needed when these derivatives must be determined. Extraction from water into chloroform is therefore a favoured first step after aqueous maceration. Partitioning from water into chloroform, however, does not by itself reduce interfering substances to a sufficiently low level. Chromato- graphy can be regarded as the “ultimate” procedure, but, in the interests of economy of time, it is always preferred to use some less complete separation if it is sufficient, such as further partitioning in a funnel, removal of easily absorbable substances on a short column, non-fractionating distillation or partial hydrolysis.Since the degree of cleaning up needed is necessarily influenced by the final determination step, these methods are dealt with in later sections. If chromatography can be taken to the stage of complete isolation of the constituent to be determined, a non-specific method of firtal determination can be used. Gas-liquid chromatography with the thermal-conductivit y method of detection has been explored as a possible tool for residue analysis.1° As apparatus and experience in its use become more widespread, this method may find more extensive application, but, in our opinion, the non- specific nature of the final determination is strongly against it. Slight changes in volatility of natural compounds produced by differing substituents in chemically non-interfering compounds could upset seriously the conclusions, unless the method is thoroughly examined for each crop.With more specific detectors, once a means has been found of avoiding inter- ference in a few types of crop, the method is likely to be general, needing only confirmation in others. The possibility of more specific methods of determining pesticides containing chlorine or sulphur is being explored.ll The object of the clean-up procedure is to reduce the contribution made to the final determination by natural plant products. It is not generally practicable to reduce this interference to zero; moreover, the interference, which is often due to unknown substances, may be extremely variable with the crop or even with its state of growth or subsequent history. It is therefore most important that blank determinations be made on samples of untreated crop, as similar as possible, except for treatment, to the crop treated with insecticide.The analyst should satisfy himself that the necessary comparison material is available and that the blank values, or at least the uncontrollable variations among them, are below the desired level of significance of the final determination. The analyst’s task is frequently made more difficult and his results less certain by failure on the part of field workers, who may be many thousands of miles away, to appreciate the necessity to supply control material. For determinations of cholinesterase the interference, as mentioned above, is more complex and in general greater than in more direct methods.It is therefore necessary to carry out parallel determinations on similar extracts of treated and untreated plant material with esterase and with insecticide added to the latter to provide the directly relevant calibra- tion curve. Various further steps have been used. IV. METHODS FOR THE DETERMINATION OF ORGANO-PHOSPHORUS INSECTICIDES Most of the methods in use for determining residues are absorptiometric, since only colour reactions are generally sufficiently selective and sensitive. Volumetric or gravimetric methods are not (except with special elaboration) applicable to the microgram amounts to be deter- mined nor sufficiently selective to be applied without an impracticable degree of separation of the insecticide from analytically interfering substances of plant origin.March, 19611 ORGANO-PHOSPHORUS INSECTICIDES I N FOODSTUFFS.A REVIEW 153 The general structure of the organophosphate insecticides may be represented as- where R, and R, are ethyl or methyl, occasionally isopropyl, and X is an organic radicle. The R, and R, substituent groups are less easily hydrolysed from the phosphorus than is the X group, and the derived alcohols are ubiquitous products of hydrolysis of natural sub- stances. Their estimation offers no useful possibility for insecticide determination. In the phosphoramides, OR, and OR, are replaced by dimethylamino- or isopropylamino-groups. In one instance, dimethylamine liberated from a phosphoramide has formed the basis of a residue method. The analytical methods in the literature fall into three groups, depending on the part of the molecule used.(1) Properties of the whole molecule, (2) Determination of phosphorus. (3) A reaction depending on some property of the group X, either while still attached to the phosphate radicle or after hydrolysis. In considering reactions of the whole molecule the most important characteristic used for analytical purposes is the property of inhibiting the cholinesterase enzymes. This subject was briefly mentioned in the introduction; its further discussion would be outside the scope of this review. Many residue methods described utilise this principle, and a review of the procedures adopted is given by Schechter.12 Catalysis of the colour-producing reaction of hydrogen peroxide on certain aromatic bases by phosphoric anhydride compounds has been shown by Epstein, Rosenblatt and Demekl3 and Marsh and Nealel* to provide a sensitive method for determining some of the phosphorus “nerve gases.” How general this method is or whether it could be applied in the presence of plant extracts is not known.The infra-red absorption spectrum is a highly characteristic property of any molecule. This method has been used for residues.16 At present it is of limited application owing to marginal sensitivity and high demands on the clean-up technique. Homsteinle has reported on possible applications of fluorimetry and finds that guthion and Potasan are fluorescent in ultra-violet light. Polarographic procedures have been employed for residue deter- minations, but no specific references to organo-phosphorus compounds are available.Methods depending on the determination of phosphorus or specific reactions of the rest of the molecule form the major methods of approach to the determination of residues. Each method has its own advantages and disadvantages; the choice between them can only be made with knowledge of the chemistry of each compound, and of the possible decomposition products that may occur in the plant, and must include consideration of the objective of the analysis. Phosphorus methods are non-specific, and the determination will include other phosphorus-containing insecticides unless these are removed in the clean-up procedure ; non-phosphorus methods can often be made specific for a single insecticide, or at least for a group of related insecticides.Such specific methods are of advantage if one of several insecticides in a food crop needs to be determined, Specificity is not always desirable in a method to be applied to a compound that may be oxidised or metabolised on or in the plant. The total-phosphorus method in these circumstances may give a more accurate measurement of all toxic products derived from the insecticide in the crop. Phosphorus methods are applicable to all compounds of this class and axe capable of development into general non-specific methods for organo-phosphorus insecticides. When surface residues only are sought, solvent stripping and then hydrolysis and determination of phosphorus can be used.17 For total residues or crops to which the previous simple technique cannot be applied, a clean-up from interfering phosphates is necessary.As already men- tioned, chloroform extraction from water is not adequately selective. The selectivity is greatly improved by adding a distillation step. This was first applied to the most volatile of the organo-phosphorus insecticides,s dimefox, on a macro scale, without preliminary extraction, and later Otter18 used micro-distillation of a chloroform extract under reduced pressure to isolate the residue from plant phosphates. This technique has been used for residues of schradan,19 and dimethoate7 and related compounds20 and is probably more gener- ally applicable. Recovery of added insecticide varies from 65 to 85 per cent. with different164 CHILWELL AND HARTLEY : DETERMINATION OF RESIDUAL [Vol.86 crops, and an untreated sample is therefore desirable. The blank values on plants known to contain no insecticide are below 0.1 p.p.m. and the method has been applied to residues in all important food crops. Laws and Webleygl used a short charcoal column to absorb interfering substances from a chloroform. solution before determining demeton-methyl residues in cabbage, lettuce and potatoes, Thimet (phorate) residues in peas and Phosdrin residues in kale and sugarbeet. Interference from plant phosphates was reduced to negligible proportions and recovery of added insecticide was 80 to 90 per cent. efficient. This technique is being investigated as a general method for organo-phosphorus insecticides. Methods depending on the non-phosphorus group have been extensively developed.They all utilise a specific reaction of the substituent group and cannot readily be classified. In most of the methods reported the residue after suitable extraction and clean-up is hydrolysed with alkali to break the P-O(S)-C link, and then the liberated organic substituent is isolated and determined. Many examples of this type will be found under the compounds listed in section V. With any method the recovery of the insecticide residue present in the sample is never complete and may vary considerably with different crops. It is essential that a method be tested on each crop by a recovery experiment in which a known amount of the insecticide to be determined is added to an untreated sample at an early stage in the analysis. Only recovery from an early stage of the laboratory procedure onwards can be measured in this way, The problem of efficiency of the initial extraction from the vegetable material must be dealt with by the methods discussed in section 11.The level of added insecticide in the “fortified” sample should be similar to the residue level expected in the sprayed crop. The isotope-dilution technique has been used in recovery experiments22; it has the advantage of application without appreciable change in the insecti- cide content of the sample, but it is still limited to the laboratory stages of the process. This application of radio labelling is distinct from its more valuable contribution, when applied to the growing crop, at an early stage of the investigation of methods for a new insecticide.V. METHODS FOR INDIVIDUAL COMPOUNDS A summary of the methods available for the determination of residues of some insecticides is given below. The insecticides in current use in this country are included, together with some others for which methods are available. Previous reviews of the literature on deter- mining insecticide residues, including organo-phosphorus compounds, will be found under references 23, 24, 25, 26, 27, 12 and 28. DEMETON- A 65 + 35 mixture of demeton 0 (diethyl 2-ethylthioethyl phosphorothionate) and demeton S [diethyl S-(2-ethylthioethyl) phosphorothiolate] Hensel et aZ.29 used a method based on cholinesterase inhibition determined on an aqueous or chloroform extract of the crop. The cholinesterase depression observed was compared with those produced by standards prepared from demeton in an extract of the untreated plant.Metcalf et aL30 compared the results of the anticholinesterase method with residues determined by =P-labelled demeton and concluded that the residues found by the enzymatic method would be high by a factor of 5 or 10 because of oxidation in the plant to more powerful inhibitors of cholinesterase. Van Middelem and Waites31 report residues determined on collards, lettuce and mustard by the cholinesterase technique. Demeton residues can be determined by the phosphorus methods described by Heath et al.19 DEMETON-METHYL- A 70 + 30 mixture of demeton-0-methyl(2-ethylthioethyl dimethyl phosphoro- thionate) and demeton-S-methyl (S-2-et‘hylthioethyl dimethyl phosphorothiolate) The chemical behaviour of demeton-methyl in the plant and the determination of residues with 32P-labelled insecticide has been described by T i e t ~ , ~ ~ who exhaustively extracted the plant with methanol.After removing the s’olvent the residue is taken up in water and extracted first with light petroleum and finally with chloroform. The toxic residue is deter- mined by measuring the radioactivity in the chloroform extract. This method is not applic- able to residues in crops for human consumption. Laws and Webley21 determined residuesMarch, 19611 ORGANO-PHOSPHORUS INSECTICIDES IN FOODSTUFFS. A REVIEW 166 by extraction of the crop with aqueous methanol or with isobutyl alcohol when a high blank value was encountered with methanol ; plant interference was avoided by chromatography on a charcoal column in chloroform solution, and the insecticide was determined colori- metrically as phosphorus after wet combustion with nitric, hydrochloric and perchloric acids.The results agree with those determined by anticholinesterase measurements. Residues can also be determined by determination of phosphorus after purification by distillation.= DIMEFOX- NNN'N'-Tetramethylphosphorodiamidic fluoride Only methods based on determining phosphorus are available for dimefox residues. Dupke, Heath and Otter6 described a method of purification by distillation under reduced pressure from a glycerol - ethylene glycol solution that is applicable to brassica crops and strawberries, and co-distillation from a paraffin macerate of the crop used for cocoa beans and hops.Field and Laws% used chromatography on a magnesia column for dimefox residues in dried hops. DIPTEREX (TRICHLORPHON)- Dimethyl 2,2,2- t richloro- 1-hydroxy e thylphosphonate The anticholinesterase method proposed by Hensel et aZ.29 has been used for residues of Dipterex on apples, French beans, lettuce and spinach.23 A detailed study of the cholin- esterase technique has been made34 and corrections applied for errors arising from spontaneous hydrolysis of the substrate, and for the conversion of Dipterex to dichlorvos (2,2-bichlorovinyl dimethyl phosphate) during the determination. Residues between 0.2 and 1.5 p.p.m. can be determined by the modified procedure. DIAZINON- Diethyl 6-methyl-2-isopropyl-4-pyrimidinyl phosphorothionate Suter et aZ.= determined diazinon by extracting the residue into 48 per cent.hydrobromic acid from a solution in light petroleum. The acid extract is boiled under reflux while a stream of nitrogen, which carries the hydrogen sulphide liberated into a zinc acetate absorbing solution, is passed through it. Methylene blue, which is determined at 670mp, is formed by reaction with P-aminodimethylaniline and ferric chloride. In Harris's as modified by Blinn and Gunther,37 diazinon is hydrolysed to 2-isopropyl-6-methyl-4-pyrimidol , interfering substances are removed by extraction from strongly acid and basic solutions and finally the pyrimidol is extracted into chloroform from a weakly acid solution and deter- mined from its absorption a t 272mp. Diazinon may also be determined by a phosphate method1' by extracting the crop with light petroleum, washing the extract to remove water- soluble phosphates, hydrolysing the evaporated residue by heating under reflux with 48 per cent.hydrobromic acid and determining phosphorus by the molybdenum-blue reaction. These three methods have been compared1' on the same samples and with results by a cholin- esterase method and found to give excellent agreement above 1 p.p.m. , but below this level there is some interference leading to divergent results. Read and Hughes3* have investigated the methylene blue and the pyrimidol methods on mushrooms and found the former preferable in being less affected by interference from the mushroom extract. DIMETHOATE- 00-Dimeth yl S- (N-met hylcarbamoylmet hyl) phosphor0 t hiolot hionate Residues on a wide variety of crops have been determined by micro-distillation and then determination of phosph~rus.~ The blank values on untreated crops are reduced to 0.1 p.p.m.and recoveries of 65 to 80 per cent. are obtained. Insecticide labelled with 32P has been used to demonstrate the efficiency of the extraction technique, and feeding tests on animals indicate that the method determines the total residue hazard present in a sprayed crop. Santi and B a ~ z i ~ ~ extracted cherries with a chloroform - acetonitrile mixture and liberated methylamine by hydrolysis with hydrochloric acid. Methylamine reacts with ninhydrin to produce formaldehyde, which is determined with chromotropic acid. The method will detect a residue of 0.2 p.p.m.; an alternative paper-chromatographic method will detect 0.6 p.p.m. of residue. Residues in olive oil have been determined by determining phosphorus after solvent e~traction.~O The phosphorus, methylamine and paper-chromato- graphic methods give recoveries of 70 to 80 per cent.156 CHILWELL AND HARTLEY : DETERMINATION OF RESIDUAL [Vol. 86 DELNAV- The bis-(00-&ethyl phosphorothiolothionic) ester of 2,3-#-dioxandithiol A specific method is described by Dunn4]- based on cleavage by mercuric chloride to glyoxal, which is converted as it is formed to the 2,4-dinitrophenylosazone, which gives an intense blue colour in alkaline solution. S CH,OH + HC=O II I + 2HCl CH,OH HC=O The crop is minced and extracted with hexane, the extract is purified by adsorption on alumina containing 2 per cent.of water and extracting with benzene. Further purification is necessary by partition chromatography with acetonitrile on a Celite column. The cleavage reaction and osazone formation is carried out in one stage, the glyoxal 2,4-dinitrophenyl- osazone is isolated and purified by chromatography on alumina. The colour is developed by adding tetramethylammonium hydroxide to a solution in dimethylformamide. Gunther et aZ.42 applied this method to residues on orange and lemon peel and reported recoveries of 106.5 and 56.0 per cent. of insecticide; they found the hexane extracts to be stable for up to 3 months when stored at 10" C. GUSATHION (GUTHION)- 00-Dimethyl S-(4-oxo-3H-1,2,3-benzotriazine-3-methyl) phosphorothiolothionate Guthion can be hydrolysedg3 to a diazonium compound, which is coupled with phenyl a-naphthylamine to give a blue-violet colour; this test is specific for guthion, but has not been applied to residues.Hydrolysis to anthranilic acid and diazotisation and coupling with 1-naphthylethylenediamine has been employed for residue determinations.& Suitable clean- up procedures are described for cottonseed, fruit, milk and chlorophyll-containing crops, the final colour development being similar to Averell and Norris's method for parathion (q.~.). The sensitivity is 0.05 to 0.1 p.p.m. of guthion according to the nature of the sample, and studies on the corresponding oxygen analogue show that it is effectively recovered from green plants. Giang and SchechterP5 hydrolysed with hydrochloric acid; formaldehyde liberated from the methylene group was distilled and then determined with chromotropic acid reagent.The preliminary clean-up involves extraction of the residue with chloroform, separation by adsorption on alumina from ;i. solution in pentane and subsequent elution with acetonitrile. Recoveries of 94 to 99 per cent. of guthion added to crushed cottonseeds are claimed and the oxygen analogue, 00-dimethyl S-(4-oxo-3H-1,2,3-benzotriazine-3- methyl) phosphorothiolate, is also determined by the method. Of other insecticides, Thimet, Trithion and Nialate [SS-bis-(00-diethyl phosphorothioate)] liberate formaldehyde under these conditions. Archer and Zweig6I determined the anticholinesterase activity of a purified extract, after oxidation, colorirnetrically with indophenyl acetate as the chromogenic substrate.MALATHION- S- 1,2-Di (ethoxycarbonyl) ethyl 00-dimethyl phosphorot hiolot hionate Norris, Vail and Averell's method4' forms the basis of all the residue methods described in the literature. The crop is extracted withL carbon tetrachloride, the insecticide is decom- posed, by alkali in ethanol - carbon tetrachloride solution, to sodium dimethyldithiophosphate and sodium fumarate. The former is extracted into water and converted to the copper complex, which is soluble in carbon tetrachloride and can be determined colorimetrically at 418 mp. A collaborative examination of the method reported by Conroy48 found it suitable for surface residues, and suggested possible improvements in technique. The basic procedure has been improved and modified for the determination of malathion in meat, fat, liver, milk and eggs.49 By the methods described the blank values on samples known to contain noMarch, 19611 ORGANO-PHOSPHORUS INSECTICIDES IN FOODSTUFFS.A REVIEW 167 malathion are reduced to below 0.2 p.p.m. and recovery values of 70 to 100 per cent. are quoted on all five products. A modified extraction for cottonseed is described by Norris and Kuchar.50 PARATHION- 00-Diet h yl p-nitrophenyl phosphorot hionate The most widely used method is that proposed by Averell and N o r r i ~ , ~ ~ in which the nitro-group is reduced to the amine, which is diazotised and coupled with N-l-naphthyl- ethylenediamine. The adaptation of the method to the routine examination of a large number of samples was discussed by Gunther and Blinn.62 The method of the Association of Official Agricultural Chemists (1955) is based on the same procedure.The sample is extracted with benzene, the extract is purified by shaking with a mixture of attaclay, kiesel- guhr and charcoal, and filtering. An aliquot of the clarified extract is reduced with zinc dust and hydrochloric acid, the filtered solution of amine is diazotised with sodium nitrite, and ammonium sulphamate and then N-1-naphthylethylenediamine hydrochloride solution are added. The optical density is measured at 550 mp. A similar method was used by GageBtm with N-/3-sulphatoethyl-m-toluidine as the coupling agent. Bazzi and Santi55 described the extraction of residues from olive oil by extraction with ether at -75" C.Vidic66 modified Averell and Norris's procedure for blood and tissue. Buckley and Colthurst57 determined parathion by alkali hydrolysis to P-nitrophenol, which was then determined at 408mp, interference from many plant pigments being overcome by oxidation with hydrogen peroxide during the hydrolysis. PARATHION-METHYL, CHLORTHION AND EPN- 00-Dimethyl $-nitrophenyl phosphorothionate 0-(3-Chlor0-4-nitrophenyl) 00-dimethyl phosphorothionate 0-Ethyl 0-P-nitrophenyl phenylphosphorothionate For the analysis of these residues Averell and Norris's method is used. Kolbezen and Reynolds58 used zinc in phosphoric acid for reducing Chlorthion residues in cottonseed to avoid yellow colours encountered in untreated samples with hydrochloric acid. PHEN KAPTON- S- (2,5-Dichlorop hen ylt hiomet h yl) 00-die t hyl phosphor0 t hiolo t hionat e Hardon et aZ.59 hydrolysed phenkapton to 2,5-dichlorothiophenol, which was then brom- inated to 2,5-dichlorophenylsulphonyl bromide.Reaction with potassium cyanide forms cyanogen bromide, which is determined colorimetrically with pyridine and benzjdine by Aldridge's method. The method is relatively specific for phenkapton, the sensitivity claimed being about 5 pg, equivalent to 0.05 p.p.m. of residue in a 100-g sample. In a method based on condensation to a thioindigo-derivative,60 the residue in methanol solution is condensed with chloroacetic acid in alkaline solution. The 2,5-dichlorophenylthioglycollic acid formed is purified and condensed in sulphuric acid to give a thioindigo-derivative, which is extracted into o-dichlorobenzene and determined at 560 mp; 20 pg of phenkapton can be detected.Phenkapton can also be determined by the micro-distillation technique and by determining phosphorus after hydrolysis with hydrobromic acid, as used for diazinon. PHOSDRIN- 1 -Carborne t hoxy- 1 -propen-2- yl dime t h yl phosphate Casida et aZ.61 modified Hensel's cholinesterase method for the determination of Phosdrin residues down to a level of 0.05 p.p.m. Dormal et used cholinesterase techniques for residues in spinach, peas and beans both as freshly harvested and after processing. Lawss3 has shown that Phosdrin may be determined by the chromatographic method for demeton- methyl. He compared the results of chromatographic and cholinesterase techniques and notes that the anticholinesterase method tends to give lower results in later-harvested samples, probably due to the quicker decomposition of the more active isomer.PHOSPHAMIDON- 2-Chloro-2-diethylcarbamoyl-1-methylvinyl dimethyl phosphate Phosphamidon residues have been determined as phosphorus after micro-distillation. Giang et a,!.* have used Hall, Stohlman and Schechter's method66 for schradan as a basis for an analytical method for phosphamidon by hydrolysis to yield diethylamine.158 CHILWELL AND HARTLEY : DE.TERMINATION OF RESIDUAL [Vol. 86 SCHRADAN- Bis-NNN’N’-tetramethylphosphorodiamidic anhydride David et aZ.66 extracted plant material by maceration with water and filtration and then hydrolysed natural plant phosphates by controlled alkaline hydrolysis, which does not affect schradan.Schradan is extracted by chloroform, digested with hydrochloric acid and perchloric acid and determined colorirnetrically as phosphorus. Good recoveries are obtained, but some crops give a blank value of up to 1 p.p.m. Heath et aZ.19 reduced plant interference to below 0.1 p.p.m. by vacuum distillation of the extracted residue. The plant is macerated with water, and the residue extracted into chloroform for alkaline solution. The dry chloro- form extract is then distilled at 1 mm pressure and 100” C on to a cold-finger condenser. The condensate on the cold-finger condenser contains schradan residue freed from interfering plant extractives, and the schradan is determined colorirnetrically as phosphorus after digestion with perchloric acid.One of the authors has used a temperature of 140” C in the distillation, which was found to give higher recoveries from some crops. Hall, Stohlman and SchechterG5 extracted the plant with chloroform, and hydrolysed in strong acid to liberate dimethylamine, which was steam-distilled frlom alkaline solution, absorbed in acid and determined as yellow cupric dimethyldithiocarbamate. TRITHION- S-(p-Chlorophenylthiomethyl) 00-diethyl phosphorothiolothionate The extract after a chromatographic clean-up is hydrolysed by alkali in ethylene glycol to P-chlorothiophenol, which is determined colorirnetrically with 2,6-dibromo-N-chloro-~- quinoneimide, the orange colour being measured at 480 mp.67 Gunther et al. used a total- chlorine method to determine residues on oranges and lemons.68 PatchetP9 discussed the difficulties involved in determining Trithion by the cholinesterase method because of the presence of more actively anticholinesterase oxidation products in aged residues. The procedure described involves extraction, separation of oils and waxes with acetonitrile, oxidation in a hydrogen peroxide - acetic acid - benzene system and then a cholinesterase procedure for the quantitative determination.Giang, Adams and Schechter70 have deter- mined Trithion by hydrolysis with alkali after extraction and acidification to liberate form- aldehyde, which is determined by colour reastion with chromotropic acid in a procedure similar to that used for Thimet residues. THIMET (PHORATE) - 00-Dieth yl S- (e thylthiome t’hyl) phosphorothiolothionate Bowman and Casida71 have shown that Thimet and five oxidation products are possibly present in plant residues.Giang and S~heclhter~~ described a method for Thimet and all metabolites by oxidation of the extracted residue to the sulphone, hydrolysis with alkali and liberation of formaldehyde from the active methylene group by chromotropic acid and sulphuric acid. Recoveries of 85 to 95 per cent. of Thimet added to the crop are claimed. Residues in peas have been determined by a modification of Laws and Webley’s method for demeton-methyl.21 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. REFERENCES Ministry of Agriculture, Fisheries & Food, “Notification of Pesticides Scheme agreed between Mills, P. A., J . Ass. Ofi. Agric.Chem., 195!3, 42, 734. Jones, L. R., and Riddick, J. A., Anal. C h e w , 1952, 24, 569. Kocher, C., Roth, W., and Treboux, J., Mitt. der Schweitz. Ent. Ges., 1953, 26 (1). DupCe, L. F., Heath, D. F., and Otter, I. K. H., J. Agric. Food Chem., 1956, 4, 233. Edson, E. F., Chem. & Ind., 1958, 697. Chilwell, E. D., and Beecham, P. T., J . Sci. Food Agric., 1960, 11, 400. Melis, R., Montanelli, P., and Mellis, G., Ann. della Sun. Publica, 1959, 20, 66. Heath, D. F., and Vandekar, M., Biochem. J., 1957, 67, 187. Coulson, D. M., Cavanagh, L. A., and Stuart, J., J . Agric. Food Chem., 1959, 7, 250. Coulson, D. M., Cavanagh, L. A., de Vries, J. E., and Walther, B., “Proc. Symp. Instrum. Methods Metcalf, R. L., Editor, “Advances in Pest Control Research,” Interscience Publishers Inc., New Epstein, J., Rosenblatt, D.H., and Demek, M. M., J . Amer. Chew Soc., 1956, 78, 341. Marsh, D. J., and Neale, E., Chem. & Ind., 1956, 494. Government and Industry,” January, 1960. for Anal. Food Additions,” Michigan Stxte University, March, 1960. York, 1957.March, 19611 ORGANO-PHOSPHORUS INSECTICIDES IN FOODSTUFFS. A REVIEW 159 16. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. McCaulley, D. E., “Proc. Symp. Instrum. Methods for Anal. Food Additions,” Michigan State Hornstein, I., J . Agric. Food Chem., 1958, 6, 32. “Methods of Analysis for Diazinon Residues,” Geigy Co.Inc., New York. Otter, I., Microchim. Acta, 1956, 125. Heath, D. F., Cleugh, J., Otter, I. K. H., and Park, P. O., J . Agric. Food Chevx, 1956, 4, 230. Bazzi, B., Monograph, Montecatini, Milan, Italy, 1957. Laws, E. Q., and Webley, D. J., Analyst, 1959, 84, 28. Metcalf, R. L., Editor, “Advances in Pest Control Research,” Interscience Publishers Inc., Fiew “Summary of methods of analysis for residues of pesticides in foodstuffs,” Report of working Westlake, W. E., Anal. Chem., 1959, 31, 724. -, Ibid., 1957, 29, 679. St. John, J. L., Ibid., 1955, 27, 654. -, Ibid., 1953, 25, 42. Gunther, F. A., and Blinn, R. C., “Analysis of Insecticides and Acaricides,” Interscience Pub- Hensel, J., Hewitt, A. E., Sheets, U. M., and Scott, R. C., Monograph, Chemagro Corp., Kansas Metcalf, R.L., March, R. B., Fukuto, T. R., and Maxon, M. G., J . Econ. Ent., 1955, 48, 364. Van Middelem, C. H., and Waites, R. E., J . Agric. Food Chem., 1958, 6, 594. Tietz, H., Hefeken-Briefe, 1956, 9, 286. Field, K., and Laws, E. Q., Analyst, 1957, 82, 667. Chemagro Corp., Kansas City, Report No. 3581, 1959. Suter, R., Delley, R., and Meyer, R., 2. anal. Chem., 1955, 147, 173. Harris, H. J., Monograph, Geigy Co. Inc., New York, 1954. Blinn, R. C., and Gunther, F. A., J . Agric. Food Chem., 1955, 3, 1013. Read, W. H., and Hughes, J. T., Glasshouse Crops Research Institute Annual Report, 1957. Santi, R., and Bazzi, B., Chimica (Milan), 1956, 12, 325; Chew. Abstr., 1957, 4632. Bazzi, B., Pietri-Tonelli, P. de, and Santi, R., Monograph, SOC.Gen. per 1’Ind. Min. e Chim., Milan, 1956; Anal. Abstr., 1957, 2830. Dunn, C. L., J . Agric. Food Chem., 1958, 6, 203. Gunther, F. A., Jeppson, L. R., Barkley, J. H., Elliott, L. M., Blinn, R. C . , and Dunn, C. L., Wollenburg, O., and Schrader, G., Angew. Chem., 1956, 68, 41. Chemagro Corp., Kansas City, Report No. 1294, 1956. Giang, P. A., and Schechter, M. S., J . Agric. Food Chem., 1958, 6, 845. Archer, T. E., and Zweig, G., Ibid., 1959, 7, 178. Norris, M. V., Vail, W. A., and Averell, P. R., Ibid., 1954, 2, 570. Conroy, H. W., J . Ass. 08. Agric. Chem., 1957, 40, 230. Norris, M. V., Easter, E. W., Fuller, L. T., and Kuchar, E. J., J . Agric. Food Chem., 1958, 6, 111. Norris, M. V., and Kuchar, E. J., Ibid., 1959, 7, 488. Averell, P. R., and Norris, M. V., Anal. Chern., 1948, 20, 753. Gunther, F. A., and Blinn, R. C., “Advances in Chemistry,” Series No. 1, American Chemical Gage, J. C., Analyst, 1950, 75, 189. -, Ibid., 1952, 77, 123. Bazzi, B., and Santi, R., Monograph, Montecatini, Milan, Italy. Vidic, E., Arzneimittel-Fovsch., 1958, 8, 719; Anal. Abstr., 1959, 3096. Ruckley, R., and Colthurst, J . P., Analyst, 1954, 79, 285. Kolbezen, M. J., and Reynolds, H. T., J . Agric. Food Chem., 1956, 4, 522. Hardon, H. J., Bruninlr, H., and van der Pol, E. W., Analyst, 1959, 84, 102. J. R. Geigy, S.A., Basle, internal report. Casida, J. E., Gatterdam, P. E., Getzin, L. W., jun., and Chapman, R. K., J . Agric. Food Chew., 1956, 4, 236. Dormal, S., Martens, P. H., Decleire, M., and de Saestiaets, L., Bull. de I’Inst. Agyon. et Sta. Recherches, Gembloux, 1959, 27, 137. Laws, E. Q., Analyst, 1959, 84, 323. Giang, P. A., Adams, A., and Schechter, M. S., Abstracts of 137th Meeting of the American Chemical Hall, S. A., Stohlman, J. W., 111, and Schechter, M. S., Anal. Chem., 1951, 23, 1866. David, A., Hartley, G. S., Heath, D. F., and Pound, D. W., J . Sci. Food Agric., 1951, 2, 310. Patchett, G. G., “Determination of R-1303 Spray Residues in Oranges, Lemons and Alfalfa,” Gunther, F. A., Carman, G. E., Jeppson, L. R., Berkley, J. H., Blinn, R. C., and Patchett, G. G., Patchett, G. G., and Batchelder, G. H., Ibid., 1960, 8, 54. Giang, P. A., Adams, A., and Schechter, M. S., Abstracts of 137th Meeting of the American Chemical Bowman, J. S., and Casida, J. E., J . Agric. Food Chem., 1957, 5, 192. Giang, P. A., and Schechter, M. S., Ibid., 1960, 8, 51. University, March, 1960. York, 1958, Volume 11. party issued by Western European Union, 1960. lishers Inc., New York, 1955. City, 1956. Ibid., 1958, 6, 210. Society, 1950, p. 72. Society, 1960, p. 4 ~ . Stauff er Chemical Co., Richmond, California, 1956. J. Agric. Food Chem., 1959, 7, 28. Society, 1960, p. 3A. Received July 22nd, 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600148

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

160 PATTERSON AND BUCHAN : DETERMINATION OF [Vol. 86 ‘L 0’ The Use of Selective Desorption from Carbon Columns u for the Determination of Maltotriose in Starch Conversion Products BY STELLA J. PATTERSON AND J. L. BUCHAN (Department of Scientij’ic and Industrial Research, Laboratory of the Government Chemist, Custom House, London, E.C.3) In an earlier paper, the determination of dextrose and maltose in starch The method has now been extended conversion products was described. to the determination of maltotriose. FULL details are given in an earlier paper1 for inaking and testing carbon columns and also for preparing and standardising the Somogyi reagent; these techniques were used in the work described here. It is therefore advisable to refer to the earlier paper, as only modifica- tions of the original process are described here in detail.The sugars present in a normal liquid glucose are shown in the chromatogram reproduced as Fig. 1 in the paper by Buchan and Savage.2 It was thought that, by a simple extension of the method for separating dextrose and maltose on a carbon column, conditions could readily be found for determining the third fermentable sugar, maltotriose (sugar “c” on Buchan and Savage’s chromatogram2), after removal of dextrose and maltose. However, the clean, quantitative separation of maltotriose from maltotetraose (sugar “d” on Buchan and Savage’s chromatogram2) proved unexpectedly difficult. With the type of column describedl and with a batch of B.D.H. charcoal from which maltose could be readily eluted (batch No. 3 from the previous paper1), variations in tem- perature and concentration of ethanol were tried and histograms were plotted.The sugars present in fractions of the eluates were also identified qualitatively by paper chromatography. It was found that increasing the concentration of ethanol or increasing the temperature led to more rapid elution of maltotriose, as might be expected. Usually, it was followed by more rapid elution of some of the maltotetraose. Different temperatures and different concentrations of ethanol gave varying success in the effective elution of maltotriose, but no completely satisfactory conditions were found for its separation from maltotetraose. There was the possibility that the elution of small amounts of maltotetraose with the maltotriose might be the result of “overloading” of the column with respect to maltotetraose, but, in experiments in which half the usual amount of liquid glucose was put on to the column, interference by maltotetraose was not reduced.8.0 r E 5.0 4.0 2.0 3.01 1 2 3 4 5 6 7 8 9 10 I 2 3 4 5 6 7 8 9 1 0 Fraction No. Fig. 1. Histogram for recovery Fig. 2. Histogram for recovery of maltose from 6-inch x 0-75-inch of maltose from 15-inch x 0-5-inch column of batch No. 4 B.D.H. column of batch No. 4 B.D.H. charcoal at 23” C charcoal a t 23” CMarch, 19611 MALTOTRIOSE I N STARCH CONVERSION PRODUCTS 161 A longer and narrower column containing the usual amount of the carbon - kieselguhr mixture was found to give much sharper elution bands for the sugars, as, for example, is shown in Figs. 1 and 2, and it was decided to find out whether conditions existed whereby such a column could be used for the separation of maltotriose.PROCEDURE FOR TESTING A BATCH OF CARBON WITH THE MODIFIED COLUMN- It was realised that conditions of temperature and ethanol concentration for eluting maltose would not necessarily be the same for the longer column as they were for the shorter column, and the new conditions had to be determined before investigating the elution of maltotriose. A column 15 inches long x 0-5 inch diameter was charged with 7 g of a mixture of equal parts by weight of carbon and kieselguhr, and, by pipette, 5 ml of a 2 per cent. solution of liquid glucose were placed on to it. The dextrose was then eluted with 100ml of water.As a starting point, 7 per cent. ethanol was chosen for eluting the maltose, this being the concentration recommended for the shorter column, and the optimum temperature for the elution was determined. It was found that this temperature was a little lower than that required for the elution of maltose by this concentration of ethanol from the shorter column. It was now possible to investigate the elution of maltotriose from the long column after having removed dextrose and maltose; this investigation was carried out in the usual way by collecting 10-ml fractions of the eluate, determining the sugar in each fraction by the Somogyi copper- reduction method and checking the purity of the eluted sugar by evaporating the remainder of each fraction under reduced pressure and testing by paper chromatography. To determine whether or not any maltotriose had been retained by the carbon, the column was finally extracted with 30ml of 50 per cent.ethanol. Half of this extract was then evaporated to small bulk, which was completely transferred to paper for chromatography. In this way, different concentrations of ethanol and temperatures could be tried. I t was found that the best conditions for eluting maltotriose were a relatively low concentration of ethanol and a relatively high temperature. Thus for batch No. 3 R.D.H. charcoal it was found that the maltotriose was cleanly eluted by 150 ml of 8 per cent. ethanol at 40" C. With this carbon the three lower sugars in liquid glucose could therefore be separated on the longer column, as described below.(1) Elute with 100 ml of water at about 15" C-dextrose recovered. (2) Elute with 100 ml of 7 per cent. ethanol at about 15" C-maltose recovered. (3) Elute with 150 ml of 8 per cent. ethanol at 40" C-maltotriose recovered. In practice it has been found more convenient to work throughout at one temperature for the elution of all three sugars. This temperature must of necessity be the high one required for the elution of the maltotriose, and the concentration of ethanol suitable for the elution of maltose at this higher temperature must therefore be determined. (Elution of dextrose is no problem as it is not adsorbed and can be eluted with water at any temperature.) For batch No. 3 B.D.H. charcoal it was found that at 40" C the maltose could be completely and cleanly eluted with 100 ml of 5 per cent.ethanol. The results of a separation of dextrose, maltose and maltotriose from liquid glucose on a 15-inch x O.5-inch column charged with 7 g of a mixture of batch No. 3 B.D.H. charcoal and kieselguhr, the temperature being main- tained at 40" C throughout, are shown in Fig. 3. The purity of each faction shown in Fig. 3 was checked by paper chromatography, which confirmed that the three sugars had been separated cleanly. After the elution of these sugars the column was extracted with 50 per cent. ethanol, and paper chromatography of this solution showed that there had been no retention of dextrose, maltose or maltotriose. To confirm that maltotriose was recovered quantitatively from the column under the conditions chosen, a known amount of this sugar was put on the column, elution was carried out in the usual way, and the sugar was determined in the eluate.Complete recoverywas obtained. PREPARATION OF PURE MALTOTRIOSE- A sample of pure maltotriose was required to standardise the Somogyi reagent and also for testing the column to prove complete elution of this sugar. Maltotriose is not available commercially and it was necessary to prepare it in the laboratory. The source was ordinary liquid glucose and from this the maltotriose was separated by the carbon column as described above. The solutions of maltotriose obtained from two such columns were combined,162 PATTERSON AND BUCHAN : DETERMINATION OF pol. 86 evaporated to small bulk under reduced pressure and applied as a streak across Whatman No.3 chromatography paper. After development, the position of the maltotriose on the chromatogram was located by cutting strips from the paper and treating them with a suitable colour-forming reagent. That part of the paper containing the maltotriose was then cut j 0 Is: J= I If? rls " w ' P- cc) out and eluted with a small amount of water. In this way a solution of some 20 mg of chromatographically pure maltotriose in about 3ml of water was obtained. The density of this solution at 15.5' C was determined in a small pyknometer, and, by using the solution factor of 3.86, its sugar content was calculated. This method of determining sugar concen- trations of this order when only a few millilitres of solution are available was tested withMarch, 19611 MALTOTRIOSE I N STARCH CONVERSION PRODUCTS 163 a solution of maltose, and perfect agreement was obtained between the known concentration and the concentration found.The validity of the method depends on the assumption that a solution factor of 3.86 can be applied to maltotriose, but we consider that any error intro- duced by the use of this factor would be negligible. A solution of maltotriose prepared in this way was suitably diluted and used to check recovery from a carbon column. It was also used to determine the heating time necessary for reaction of this sugar with the Somogyi reagent, the time found being 20 minutes, and to standardise the Somogyi reagent. Ideally, each batch of this reagent should be standardised, but in view of the difficulty of obtaining pure maltotriose the figures we obtained on a batch are shown below, and there would probably be little error if these were accepted for all batches made up in the same way.Maltotriose (20 minutes' heating), mg . . 1.5 1.25 1.0 0.83 0.6 0-25 Volume of 0.006 N sodium thiosulphate, ml 3.73 3.03 2-43 1.97 1.20 0.54 MALTOTRIOSE CONTENT OF LIQUID GLUCOSE- With batch No. 3 B.D.H. charcoal under the conditions shown in the histogram (Fig. 3), the dextrose, maltose and maltotriose contents for three different types of liquid glucose were determined. The dextrose and maltose contents have previously been rep~rted.~ After removal of the three sugars, the column was washed with 30 ml of 50 per cent. ethanol, half of it was evaporated to near-dryness for chromatography, and the absence of maltotriose was confirmed.A portion of the maltotriose eluate was similarly treated, and the presence of pure maltotriose was confirmed. Results for the determination of dextrose, maltose and maltotriose in liquid glucose are shown in Table I. TABLE I DEXTROSE, MALTOSE AND MALTOTRIOSE CONTENTS OF LIQUID GLUCOSE Manufacturer's description Dextrose found, Maltose found, Maltotriose found, of sample % w/w % w/w % w/w Normal (43" Baum6) . . . . .. 16.4 11.3 11.1 High dextrose equivalent (43" Baum6) . . 22.5 13.2 11.1 Low dextrose equivalent (41.5" Baum6) 10.3 8.2 8.7 We have found that use of the longer column described above is more time-consuming and in general less convenient than the original shorter column. We would therefore recommend that, where figures for only dextrose and maltose are required, the short column should be used as originally proposed, and the longer column should be used only when a figure for maltotriose is also required. We thank the Government Chemist, Department of Scientific and Industrial Research, for permission to publish this paper. REFERENCES 1. 2. 3. Patterson, S. J., and Savage, R. I., Analyst, 1957, 82, 812. Buchan, J. L., and Savage, R. I., Ibid., 1952, 77, 401. Patterson, S. 3., and Buchan, 3. L., Ibid., 1960, 85, 75. Received November loth, 1900

ISSN:0003-2654    

DOI:10.1039/AN9618600160

出版商:RSC    

年代:1961

数据来源: RSC

摘要:

164 KIRKWOOD, MITCHELL AND ROlSS AN EXAMINATION [Vol. 86 An Examination of the Occurence of Honeydew in Honey Part II* BY K. C. KIRKWOOD, T. J. MITCHELL AND I. C. ROSS (Department of Chemical Technology, Royal College of Science and Technology, Glasgow, C. 1) Twenty-eight honeys were analysed for moisture, ash, colloid, dextrin and reducing sugars, and values for specific rotation and pH were measured. The efficiency of Kirkwood, Mitchell and Smith’s linear discriminant function, based on the results for ash, pH and reducing sugars, for distinguishing honeydew from floral honey (in particular ling-heather honey) was confirmed. Eleven of the samples tested contained honeydew. PLANTS normally produce sufficient nectar to supply the bee colony with enough honey to ensure its survival, but in periods of prolonged drought the flow of nectar greatly diminishes, and the bees must augment the supply of honey from other sources of sugar.In such condi- tions, they will often collect honeydew, a sweet and sticky fluid excreted on foliage by leaf- sucking insects, mainly aphids and scale insects. The collection of honeydew is a nuisance to beekeepers, since the honey then produced is often too dark and rank-flavoured for sale and, more important, bees feeding on it may be greatly weakened or killed. As the obvious method of preventing harm to the bees is to remove honeydew honey from the hive, its identification is important. In a previous paper,l Kirkwood, Mitchell arid Smith reported the analysis of forty-two honeys for moisture, colloid, nitrogen, dextrin, reducing sugars, free acidity and ash ; specific rotation and pH were also measured.The results were subjected to discriminatory analysis, and a linear discriminant function, x, was evolved, the value of X being given by the equation- in which x1 is the pH, x2 is the percentage of ash and x3 is the percentage of reducing sugars. The numerical value of this function for any sample serves to classify the sample as floral or honeydew in origin. The mean values of X for authentic floral and honeydew honeys were found to be 86.7 and 57.6, respectively. In practice, any honey found to have a value of X greater than 73-1 may be classified as floral, and a honey having a value less than 73.1 may be classified as honeydew. Scottish heather honey is often very dark in colour and may resemble honeydew honey in appearance.Various workers2 s3s4 have analysed eighty-eight samples of heather honey, mainly ling, many of which gave high values for ash, pH and colloid content. However, the reducing-sugar contents of these samples were not determined, so that the value of the discriminant function1 could not be calculated. The object of this work was to test the efficiency of the discriminant function in dis- tinguishing honeydew from floral honey, in particular Scottish heather honey, and, if necessary, to evolve a supplementary discriminant function for distinguishing honeydew from ling- heather honey, the higher colloid content of the latter being included as an extra term in the original function. METHODS ASH, COLLOID, pH AND MOISTURE- content were carried out as described previou~ly.~ REDUCING SUGARS- the use of methylene blue as internal indicator, was used.X = -8.3~1 - 12.3X2 + 1*4X3 The cleaning of samples and determinations of sulphated ash, colloid, pH and moisture Lane and Eynon’s volumetric methodJ5 involving reduction of Fehling’s solution and * For details of Part I of this series, see reference list, p. 165.TABLE I VALUES FOUND FOR VARIOUS HONEYS Sample No. 18G 16G 17G 15G 13G 25G 23G 9G 21G 4G 1G 2G 24G 6G 22G 11G 14G 26G 1OG 28G 7G 3G 5G 8G 19G 27G 12G 20G Type of honey* Locality F F F F F F F H F H H H F H F H F F H F H H H H F F F F Perthshire, Scotland Ballindarroch, Scotland Drummond Hill, Scotland Alness, Scotland Oxford, England Angus and Dinnet, Scotland Kincardineshire, Scotland Grafrath, Germany Loch Lomond area, Scotland Switzerland Puchberg, nr.Vienna, Austria Lunz, nr. Vienna, Austria Loch Davon. Aberdeen, Deggendorf, Germany Loch Kinord, Aberdeen, Scheibbs, Austria Muir of Ord, Ross-shire, Lumphanan, Aberdeen, Scheibbs, Austria Ballindarroch, Scotland Scotland Scotland Scotland Scotland Landshut and Passau , Germany Deggendorf, Germany Frieberg, Germany Kyle of Lochalsh, Scotland Ballindarroch , Scotland Germany Ballindarroch, Scotland Kyle of Lochalsh, Scotland Suggested source Raspberry and clover Bell heather Lime and clover - Raspberry and clover Ling heather Pine (Pzcea excelsa) White clover Forest (honeydew) Common spruce and silver fir Common spruce and raspberry Ling heather Mainly pine, some fir and beech Ling heather Pine (Picea excelsa) Pressed heather Blaeberry ( Vaccinium Fir (Abies pectinata) Ling heather Meadowland and pine- myrtilZus) wood - Mainly pine, some fir and beech Fir (A bies' pectinata) Bell heather Mainly ling Ling heather Pressed heather Approximate date of extraction Colour 1951 1954 1955 1944 1951 1959 1952 1951 1951 1952 1959 1969 1959 1959 1959 1959 1956 1959 1956 1959 1969 1951 1959 1959 1950 1959 1958 1959 Lemon - buff Dark brown Lemon Dark brown Dark brown Yellow - brown Red - brown Light brown Dark brown Green - brown Dark amber Dark amber Apricot Brown - khaki Dark buff Buff Apricot Peach Dark green Buff Brown - orange Dark brown Dark khaki Khaki - green Brown - orange Buff Apricot Buff State Fine granulation Coarse granulation Fine granulation Coarse granulation Very coarse granulation Beginning to granulate Coarse granulation Beginning to granulate Coarse granulation Liquid Liquid Liquid Liquid Beginning to granulate Fine granulation Fine granulation Fine granulation Liquid Flavour Very sweet Very sweet T r e a c 1 e Treacle Very sweet Sweet Caramel Treacle Fairly sweet Very sweet Very sweet Fruity Very sweet Very sweet Fairly sweet Clover Fruity Syrupy Very viscous liquid Treacle Very fine Fairly sweet Liquid Very sweet Very coarse Rum Very viscous liquid Fairly sweet Liquid Very sweet Medium Fairly sweet Very fine Fairly sweet Very fine Fairly sweet Fine granulation Strong (sweet) granulation granulation granulation granulation granulation PH 4.00 4.17 4-24 4-30 4.37 440 4.42 4.48 4-48 4.58 4.70 4-70 4.70 4.7 1 4.73 4.74 4.74 4-76 4.78 4.82 4.83 4.89 4.92 4.96 4-99 5-05 5-11 5.42 Ash on material , 0.76 0.65 0.16 0.70 0-56 0.18 0.43 1.18 0.57 0.91 0.90 0.99 0.49 0.91 0.49 0.85 0.64 0.85 1.14 0.50 0.88 1.31 0.95 1.01 0-3 1 0-44 0-64 0.56 dry.% Dextrin on dry material , 1.41 3.04 1.00 3.00 0.44 1.61 1.02 3.49 3.45 3-13 4-16 4.81 1-20 4.04 0.38 3.57 1-14 2-16 2.98 1.24 9.76 5.37 5-85 4.45 0.62 0.83 0.83 0.40 % Specific rotation, a:' degrees - 12.82 - 5.23 - 11-73 - 3.21 - 22.80 - 14.10 - 16.10 + 12-48 - 1.97 + 9.54 +4*90 + 4.29 - 21.72 +4.11 - 18.13 + 3.48 - 14.32 - 10.47 + 9.55 - 17.40 + 11-27 + 9.35 + 4.94 + 2.87 - 18.30 - 19.20 - 17.69 - 19.46 Colloid material, on dry 0-17 0.72 0.12 0.34 1-75 0.43 1.13 0.11 0-26 0.31 0.39 0.36 1.49 0-38 1.71 0-24 2-18 0.29 0.3 1 1-67 0.30 0.1 3 0.2 7 0.24 0.64 1.65 2.28 2.00 % Moisture content, 19.2 18.6 17.0 19.9 21.0 16.6 14.2 13.5 18.2 16.0 16.1 17.2 18-5 15.1 18-5 17.4 20.1 18.1 16.1 15.9 16.4 19-4 13-9 14.2 19.2 18.3 19.9 19.6 % Reducing sugars on dry material, % 92.6 84.0 94.3 85.2 88-8 93.4 93.8 75.2 86.2 74.8 77.3 81.7 96.3 78.0 96.8 76.9 91.9 88.2 75.5 91.2 67.6 72-3 77.9 76-7 95-9 91.9 94.2 96.3 Value of discrim- inant function (XI 87.0 75.0 94.8 74.9 81.1 92.0 89.3 53.6 76-5 55.5 58.1 63.2 89.8 58.8 90.2 57.8 81.3 73-5 52.0 81.5 43-7 44-5 55.5 53-8 89.1 81.3 81.6 82.9 * Floral honey = F; honeydew honey = HMarch, 19611 OF THE OCCURRENCE OF HONEYDEW IN HONEY.PART 11 165 SPECIFIC ROTATION AND DEXTRIN CONTENT- were carried out as described previous1y.l The determinations of specific rotation and dextrin content (by precipitation with ethanol) RESULTS The results of the various tests, arranged in order of increasing pH, are shown in Table I ; Table I1 shows the ranges of values obtained in some of the tests.TABLE I1 RANGES OF VALUES FOR FLORAL AND HONEYDEW HONEYS Floral honey r \ Minimum Maximum Average A Colloid content, % . . . . 0.12 2.28 1.11 Dextrin content, % . . . . 0-38 3-45 1.40 Specific rotation, degrees . . -22-80 -1.97 -14.39 Reducing-sugar content, yo . . 84.0 96.9 91.8 Ash content, yo .. . . 0.16 0.85 0.53 pH . . .. . . . . 4-00 5-42 4.63 Discriminant function, X . . 73-5 94.8 83.6 Honeydew honey Minimum 0.11 2.98 + 2.87 67.7 0-85 4-48 43.7 Maximum 0.39 9.76 + 12-48 81.7 1.31 4.96 63.2 1 Average 0.28 4.69 + 6.98 75.8 1.00 4-75 64.3 Ling-heather honey was readily identified by its high colloid content.As before,l for samples having the same colloid content, honeydew honeys were much darker, possibly indicating that less of their colouring matter was present in a colloidal state. The dextrin contents found for honeydew honeys, greater than those of the floral honeys, were in agreement with the previous results.1 All the honeydew honeys were dextro-rotatory and all the floral honeys laevo-rotatory. The reducing-sugar contents of the honeydew honeys were markedly lower than those of the floral honeys; this agrees with previous resu1ts.l The ash contents of the honeydew honeys were slightly higher than those of the ling- heather honeys, but the ranges of values found for both types were not sufficiently different to give a reliable test for honeydew honey.Measurements of pH were found to be useless in discriminating between ling-heather and honeydew honeys, as the ranges of pH values for both types of honey were almost coincident. Values of the discriminant function, X,l were calculated and found to give satisfactory discrimination between the honeydew and floral honeys. The average values of X for honeydew and floral honeys agreed closely with those found previously1 and with more recent unpublished results (September, 1960; personal communication from J. W. White , jun. , U.S. Department of Agriculture , Agricultural Research Service, Philadelphia, Pa.). White, in an investigation of five hundred American honeys, obtained average values for X of 88.3 for floral honey and 56.4 for honeydew honey. We gratefully acknowledge the valuable help given by many beekeepers, who supplied the samples of honey, and in particular by Dr. E. P. Jeffree, Aberdeen University, who arranged for the collection of samples. We also thank Mr. A. Cochrane for practical assistance. REFERENCES 1. 2. 3. 4. 5. NOTE-Reference 1 is to Part I of this series. Kirkwood, K. C., Mitchell, T. J., and Smith, D., Analyst, 1960, 85, 412. Cameron, M. D., Mitchell, T. J., and Westwood, M., Scottish Beekeeper, 1952, 28, 120. Mitchell, T. J., Donald, E. M., and Kelso, J. R. M., Analyst, 1954, 79, 435. Mitchell, T. J., Irvine, L., and Scoular, R. H. M., Ibid., 1955, 80, 620. Lane, J. H., and Eynon, L., J . SOC. Chern. Ind., 1923, 42, 32~. Received November 3rd, 1960

ISSN:0003-2654    

DOI:10.1039/AN9618600164

出版商:RSC    

年代:1961

数据来源: RSC