bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of Carotene Stereoisomers in Vegetables
Authors: Sweeney J P , Marsh A C
Published: February 2020

A high pressure liquid chromatographic method has been developed for separation of provitamin A carotene stereoisomers in vegetables. A column designed to withstand high pressures is packed tightly with a mixture of calcium and magnesium hydroxides. An elution mixture of 1.5%p-methylanisole in petroleum ether is forced through by nitrogen pressure. Resolution of as many as 7 isomers is obtained in less than 1 hr. The principal stereoisomer of all-trans-β-carotene in green vegetables was found to be neo-β-carotene U. In red and yellow vegetables, it was neo-β- carotene B.
Constituents of Olibanum Oil: Sesquiterpene Hydrocarbons
Authors: Yates Ronald L , Wenninger John A
Published: February 2020

The sesquiterpene hydrocarbons of a commercial sample of olibanum oil were isolated and purified by a combination of techniques, including column chromatography, silver nitrate adduction, distillation, and preparative GLC. Most components were identified by their IR spectra. In some cases NMR spectra were used for identification. A total of 27 sesquiterpene hydrocarbons were identified: δ-elemene, α-cubebene, α-ylangene, α-copaene, β-bourbonene, α-gurjunene, β-elemene, transa- α-bergamotene, α-guaiene, β-ylangene, caryophyllene, β-copaene, aromadendrene, thujopsene, allo-aromadendrene, α–+ β-humulene, selina-4,ll-diene, γ-muurolene, α-muurolene,β-selinene, α-selinene, δ-cadinene, γ-cadinene, “cubenene”, β-cadinene, calamenene, and α-calacorene. The identification of β-ylangene and β1-cadinene are tentative.
Effects of Various Germicidal Chemicals on H.Ep. 2 Cell Culture and Herpes simplex Virus
Authors: Blackwell J H , Chen J H S
Published: February 2020

The disinfectant present in most disinfectant-virus mixtures is inherently toxic to cell cultures and thus precludes the observation of viral inactivation at low dilutions of virus. Therefore, a method employing Sephadex was devised which would remove the cytotoxic activity of virus-disinfectant mixtures. These studies show that Sephadex is an acceptable detoxicant for numerous low molecular weight compounds and does not affect the biological activity of Herpes simplex virus. Data are presented on the effect of low molecular weight chemical compounds, i.e., phenol, ethyl alcohol, quaternary ammonium compounds, and halogens, on H.Ep. 2 cell culture and the macroplaque strain of H. simplex virus.
Microcolumn Chromatographic Cleanup for the Analysis of Pesticides in Water
Authors: Law Leroym M , Goerlitz Donald F
Published: February 2020

Rapid and economical removal of extraneous co-extractives from pesticide residue extracts of water is made possible by the use of microcleanup columns. Three adsorbents–alumina, silica gel, and Florisil–as well as a variety of solvent systems were investigated. The recovery and cleanup of aldrin, chlordene, p,p’-DDD, p,p’-DDE, o,p’-BDT, p,p’-DDT, dieldrin, endrin, heptachlor, heptachlor epoxide, hexachlorobicycloheptadiene, hexachlorocyclopentadiene, isodrin, lindane, and methoxychlor were satisfactory, using any of the 3 adsorbents. The phosphorothioate pesticides malathion, methyl parathion, and parathion, however, could not be successfully recovered from Florisil when a modified Mills procedure was attempted. The micro-cleanup columns may also be used to perform a preliminary separation of a number of compounds that are difficult to resolve by GLC.
Quantitative Method for Determination of DDT and DDT Metabolites in Blood Serum
Authors: Dale William E , Miles James W , Gaixes Thomas B
Published: February 2020

A new method for the extraction and determination of DDT and related materials in blood has been developed. Rats were given a single oral dose of 14C-labeled DDT, and it was demonstrated by parallel gas chromatographic and radiometric measurements that in vivointroduced DDT and related materials could not be removed quantitatively from serum by simple hexane extraction. Pre-treatment of the serum with equal volumes of formic acid released the binding of DDT and DDT metabolites and permitted the extraction of these materials with n-hexane, yielding 95% recovery. When applied to sera of men from the general population and of men who had been exposed to DDT for more than 10 years in a manufacturing plant, this method gave consistently higher results than did the simple hexane extraction method.
Note on Rapid Procedure for Determining Percentage of Fat in Egg Yolk for Application in Pesticide Residue Analyses
Authors: Woods Leon A , Castle William T
Published: February 2020

A method is described for the determination of percentage of fat in egg yolk. Egg yolks are digested in hot perchloric-acetic acid mixture in Paley cheese bottles. After digestion the liquefied fat is brought up into the neck of the cheese bottle with hot perchloric-acetic acid mixture containing 0.01% acridine orange dye. The column of fat in the neck of the bottle is measured with dividers under longwave ultraviolet light. The average value found for 124 pheasant eggs collected over a 31/2 month period is 26.7% with a standard deviation of 2.9%. This average value is within the normal variation to be expected in a group of pheasant eggs. The method has been found widely applicable to other avian eggs and other tissues.
Collaborative Study of the Hemoglobin Repletion Test in Chicks and Rats for Measuring Availability of Iron
Authors: Pla Gwendolyn W , Fritz James C
Published: February 2020

The widespread incidence of iron deficiency anemia caused by insufficient iron intake and poor utilization of dietary iron sources prompted the search for a method which would be a reliable measure of availability. A hemoglobin repletion method has been proposed and studied collaboratively with 8 participating laboratories. The collaborators reported chick or rat data on the availability of supplemental iron from 5 uniform sources. There was very good agreement between collaborators. Expressed as relative biological values, versus ferrous sulfate = 100, the results on the other 4 samples were as follows: Sample 2 = 12±0.9; Sample 3 = 13±7.7; Sample 4 = 46±17.9; and Sample 5 = 3±4.5. Increases in plasma iron in human volunteers, following test doses of these samples, ranked these 5 samples in the same order as did the chick and rat hemoglobin repletion test. It is recommended that the hemoglobin test for measuring availability of iron be adopted as official first action.
Analysis of Allura Red AC Dye (A Potential New Color Additive)
Authors: Marmion Daniel M
Published: February 2020

Allura Red AC dye is a proposed new color additive. Methods are presented for the analysis of pure dye content, uncombined intermediates, subsidiary dyes, volatile matter, water-insolubles, and metals, and determination of the dye in food products such as ice cream, wieners, and hard candy.
Automated Trinitrobenzene Sulfonic Acid Method for Protein Analysis in Forages and Grain
Authors: Gehrke Charles W , Wall Larry L
Published: February 2020

The automated TNBS method to analyze protein has been modified so that 6N hydrolysates of grain and other samples can be analyzed directly without the time-consuming removal of HCl. A diluted sample of pH 8.5 for color development is achieved by placing 2 water dilution lines in 0.8N NaOH. The wash between samples is 6N HCl. Samples analyzed by the modified method and by the AOAC Kjeldahl method gave comparable results.
Collaborative Study of a Method for Extractable Color in Paprika and Paprika Oleoresin
Authors: Rosebrook D D
Published: February 2020

A collaborative study of the method for extractable color in paprika and paprika oleoresin was conducted, utilizing the facilities of member laboratories of the American Spice Trade Association. The color in paprika or other capsicum spice is extracted with acetone and the absorbance is measured at 460 nm. The method incorporates a standard color solution as a spectrophotometer check. The average coefficient of variation for all samples studied collaboratively is 6.2%. The method is recommended for adoption as official first action.
Determination of Total Solids in Frozen Spinach
Authors: Winter F H
Published: February 2020

Additional collaborative studies on the method proposed were conducted. The standard deviation for 11 collaborators was 0.103 for frozen spinach averaging 7.87% solids and 0.129 for frozen spinach averaging 5.43% solids. It is recommended that the method be adopted as official first action.
Collaborative Study of a Potentiometric Titration Method for Determining the Sodium Chloride Content of Canned Vegeable Products
Authors: Brammell Wallace S
Published: February 2020

A potentiometric method was compared with the official method, 32.018, for determining the sodium chloride content of canned vegetable products. The proposed method was very easy to use, simple, dependable, accurate, precise, and much faster than the present official method. The collaborative study consisted of 8 processed vegetable samples (canned tomato paste, sweet peas, green beans, yellow corn, sauerkraut, dill pickles, and 2 olive samples) submitted to 9 laboratories. The data from one collaborator were not included in the report because they differed too much from the others. The study indicated good agreement with the official method and very good precision as shown by the low standard deviations. It is recommended that the method be adopted as official first action. Further study is also recommended.
A Multimycotoxin Detection Method for Aflatoxins, Ochratoxins, Zearalenone, Sterigmatocystin, and Patulin
Authors: Stoloff Leonard , Nesheim Stanley , Yin Lillian , Rodricks J Y , Stack Michael , Campbell A D
Published: February 2020

In response to the need for a more comprehensive and simple procedure for multiple mycotoxin detection than had heretofore been deyised, a method has been developed for detection of aflatoxins B1, B2, G1, and G2, ochratoxins A and B and their ethyl esters, zearalenone, sterigmatocystin, and patulin. The method is based on selective extraction with acetonitrile-water, defatting with isooctane, and removal of water-soluble components by transfer of the mycotoxins to chloroform. The method has been applied to corn, barley, oats, and wheat. The detection limits achieved are not as low as can be attained with the analytical procedures for the individual mycotoxins, but are low enough to be useful in a screening procedure.
Collaborative Study of a Method for Multiple Chlorinated Pesticide Residues in Fish
Authors: Carr Richard L
Published: February 2020

Eight laboratories participated in a collaborative study of a method for chlorinated pesticide residues in fish. Gas chromatography was used for quantitative measurement of the residues. The study consisted of 3 fish samples; 2 were fortified with each pesticide at 2 levels and the third sample contained incurred residues of p,p′-DDE and p,p′-TDE. Average recoveries for both fortified levels were: α-BHC, 92.2±14.9%; heptachlor epoxide, 91.6±8.8%; p,p′-DDE, 87.5±13.5%;p,p′-TDE, 88.6±11.4%; p,p′-DDT, 90.6±9.7%; and dieldrin, 82.2±25.4%. In most instances, residues were confirmed by TLC. The method has been adopted as official first action for determination of residues of these 6 pesticides in fish.
Collaborative Study of the Determination of Dithiocarbamate Residues by a Modified Carbon Disulfide Evolution Method
Authors: Keppel George E
Published: February 2020

A modified method for determination of dithiocarbamate residue recoveries from grain was studied collaboratively. In this method dilute acid with stannous chloride is added to the crop, which is then heated to boiling for the dithiocarbamate decomposition step. A mixture of NaOH solution and benzene is used to trap hydrogen sulfide and other volatile interferences. Collaborative results were low and erratic, with large coefficients of variation. The results of the Associate Referee, on the other hand, were better. Further study on this method is recommended.
Collaborative Study of the Extraction of Light Filth from Whole Wheat-Based Ready-to-Eat Breakfast Cereals
Authors: Dent Russell G , Brickey Paris M
Published: February 2020

A method has been developed for the extraction of light filth from wheat-based ready-to-eat breakfast cereals. The method utilizes acid digestion followed by wet sieving and washing with isopropanol, then trapping with a heptane-paraffin oil mixture from a sodium oleate-40% iso propanol solution. A collaborative study resulted in 75% average recoveries of spike elytral squares and rodent hairs from wheat-based cereals. The method, as developed for oat-based cereals, resulted in debris-laden filter papers and therefore was judged ineffective. The method has been adopted as official first action for wheat-based cereals. Further studies are recommended for oat-based cereals.
Automated Colorimetric Determination of Phenylephrine Hydrochloride in Drug Formulations. II. Collaborative Study
Authors: Margosis Michel
Published: February 2020

The automated colorimetric method designed by Lane for the analysis of phenylephrine HCl in drug formulations has been submitted to a collaborative study. Five samples, including 2 with known interferences, were sent to 9 collaborators. The results were subjected to statistical evaluation. These show good recovery and a maximum interlaboratory coefficient of variation of 4.5%. The automated method as evaluated in this study has been adopted as official first action.
Collaborative Study and Ion Exchange Method for the Determination of Methyldopa, Chlorothiazide, and Hydrochlorothiazide in Drug Mixtures
Authors: Chu Rod
Published: February 2020

A method for the assay of methyldopa with either chlorothiazide or hydrochlorothiazide was studied collaboratively by 8 laboratories. The method involves the use of AG50-4X, 100-200 mesh H+ cation exchange resin to resolve the compounds. The thiazides pass freely through the resin column, while methyldopa is retained and subsequently eluted with 1N methanolic HCl. The components are quantitatively measured by spectrophotometry at 280 (methyldopa), 277 (chlorothiazide), and 270 nm (hydrochlorothiazide). For the methyldopa-chlorothiazide combination, the overall average recovery for methyldopa was 98.5% with a standard deviation of 2.50; and for the methyldopa-hydrochlorothiazide combination, 96.4% with a standard deviation of 2.30. The average recoveries for chlorothiazide and hydrochlorothiazide were 99.6 (standard deviation of 1.14) and 98.8% (standard deviation of 2.92), respectively. The method has been adopted as official first action for the determination of methyldopa and chlorothiazide in combination.
Identification of Phenothiazine Derivatives and Analogs by X-Ray Diffraction. II. Active Substances in Pharmaceutical Formulations
Authors: De Leenheer A , Heyndrickx A
Published: February 2020

Procedures have been developed for the isolation of phenothiazines and chemically related compounds from pharmaceutical formulations, namely, injections, solutions, tablets, coated tablets, creams, sirups, lotions, and suppositories. In general, active substances are crystallized as picrates. A few compounds, however, gave better crystalline derivatives as free bases (levomepromazine and propericiazine), quaternary ammonium salt (thiazinamium), or chlorhydrate salts (amitriptyline and nortriptyline). The crystalline derivatives prepared were specifically identified by comparison of their Debye-Scherrer X-ray diffraction patterns with those for reference compounds obtained under the same conditions.
Atomic Absorption Spectroscopy for Determination of ppm Quantities of Copper and Nickel in Tea
Authors: Burke Keith E , Albright C H
Published: February 2020

An atomic absorption spectroscopic method is described for the quantitative determination of 0.0005–0.01% (5–100 ppm) copper and nickel in tea. After acid decomposition of the organic material, the sample is aspirated into an air-acetylene flame. Radiation at 324.7 nm from a copper hollow cathode is passed through the flame, and the attenuation is measured. The measurement is also made with radiation at 232.0 nm with a nickel hollow cathode. The spectrophotometer is calibrated with known concentrations of copper and nickel in the presence of a matrix similar to that of the samples. The method is applicable to all teas regardless of their geographical origin. Results from 7 collaborators on 6 samples are given. For one sample from 7 collaborators the following mean standard deviations were obtained for 32 determinations: copper 19.5±1.7 ppm and nickel 26.0±1.0 ppm. The method has been adopted as official first action.
Collaborative Study of Infrared Analysis of Dicamba–2-Methyl-4-Chlorophenoxyacetic Acid and Dicamba–2,4-Dichlorophenoxyacetic Acid Formulations
Authors: Malina Marshall
Published: February 2020

A collaborative study was conducted on direct and indirect infrared methods of analysis for both dicamba-MCPA aqueous formulations and dicamba-2,4-D aqueous formulations. Twelve laboratories participated in this study, including 3 international CIPAC member laboratories. The indirect methods require acidification, followed by extraction of the formulation samples before quantitative measurement, which is performed by comparing the absorbance of the sample to that of a prepared reference standard. In the direct methods, the absorbances of solutions of the untreated sample are directly compared with those of the prepared reference standard. The results on both formulations from the 12 collaborating laboratories exhibit excellent precision and accuracy for the indirect infrared method, with the following coefficients of variation: dicamba-MCPA, 0.059 and 0.063, respectively; and dicamba-2,4-D, 0.057 and 0.091, respectively. The method has been adopted as official first action. Five laboratories participated in the study of the direct infrared methods and, although results indicate that these methods also exhibit excellent precision, the accuracy obtained is less than desirable.
Semiautomated Determination of Nitrogen and Phosphorus in Feedstuffs
Authors: Law A R , Nicolson N J , Norton R L
Published: February 2020

A method is described which enables nitrogen and phosphorus in a wide range of feedstuffs to be determined from a single digestion. The method employs a conventional digestion on a semimicro scale followed by automated colorimetric analysis of the resulting ammonia and orthophosphate by the indophenol blue and molybdenum blue methods, respectively. Nitrogen is determined in the range from 0 to 15% and phosphorus in the range from 0 to 4%; the rate of analysis is 40 and 30 samples/hr, respectively, after digestion and dilution. The results obtained do not differ significantly from those obtained by proven manual methods, while considerable time, space, and reagents are saved.
Determination of Trace Amounts of Mercury in Fish Tissues: Results of a North American Check Sample Study
Authors: Uthe J F , Armstrong F A J , Tam K C
Published: February 2020

Three homogenized fish samples were distributed to 29 laboratories for analysis for mercury content. The majority (19) of the laboratories used acid digestion followed by atomic absorption analysis to measure the mercury content. Six laboratories used neutron activation; while 2 used dithizone methods and 2 used pyrolysis followed by flameless atomic absorption. Results from 4 laboratories were grossly aberrant or incomplete. Graphic analysis of the results on 2 samples showed that most laboratories tended to get either high or low results with both samples and that several had more consistent results with low fat samples than with high fat samples. Comparison of the combined results by flameless atomic absorption spectroscopy with those obtained by the flame method (t-test) showed that the latter gave just significantly lower results but much poorer precision. Differences between the combined results by flameless atomic absorption spectroscopy and those by neutron activation were probably insignificant.
The Ethical Obligations of the Forensic Scientist in the Criminal Justice System
Authors: Starrs James E
Published: February 2020

There is a definite need for standardization in the obligations of an ethical and moral character imposed upon the forensic scientist both prior to and during the trial. The responsibilities of the forensic scientist as a quasiimpartial witness or as a witness for either of the contending sides are analyzed with particular references to actual cases, some of which have drawn the attention of the courts in lengthy judicial opinions. Certain rough standards are proposed with particular instances in mind. In addition, more generalized criteria are suggested which should bind the activities of the forensic scientist in the criminal justice system. The matter of tactics and strategy is evaluated in connection with the description of ethical and moral norms to guide the forensic scientist, Use of the Microscope in Criminalistics
Use of Neutron Activation Analysis for the Characterization of Paper
Authors: Brunelle R L , Washington W D , Hoffman C M , Pro M J
Published: February 2020

A controlled study was carried out on 600 samples of various types of white and colored paper obtained from 10 different paper manufacturers with known production histories and dates. Neutron activation analysis was employed to measure the characterizing trace elemental compositions. Results indicated that (1) the papers examined were uniform with respect to their trace elemental compositions, (2) papers produced by different manufacturers are readily distinguishable qualitatively and/or quantitatively, (3) different batches of paper produced by the same manufacturer are generally qualitatively similar if produced within a short span of time (however, these specimens can be distinguished by quantitative analysis of the trace elements), and (4) different batches of paper produced by the same manufacturer at least 1 year apart are readily distinguishable qualitatively and/or quantitatively.
An Automatic Spotter for Quantitative Thin Layer and Paper Chromatographic Analysis by Optical Scanning
Authors: Getz Melvin E
Published: February 2020

An automatic spotting device was designed that facilitates the spotting of samples and standards on TLC plates and paper chromatograms. It also standardizes the method of application so that optical scanning techniques can be used for quantitative determinations.
Protein Interference in Thiabendazole Determination
Authors: Jeffus Marshall T , Kenner Charles T
Published: February 2020

Protein in sufficient quantities interferes in the reductive step in determination of thiabendazole by AOAC Method II (38.154–38.157) but not by Method I (38.149–38.153). Limited results indicate that modification of Method I to allow measurement in the ultraviolet provides a simplified method of analysis for some feeds.
Effect of Reduced Drying and Extraction Time in Determining Meat Fat Content
Authors: Cohen Edward H , Swift Clifton E
Published: February 2020

The AOAC method for determining the fat content of meat was modified so that it can be applied more rapidly by processors in controlling meat product composition. A saving of 4.25 hr in drying and extraction time was effected without any significant loss in accuracy. Collaborative studies are suggested to reduce the time requirements for the official fat analysis of meat.
Gas-Liquid Chromatographic Determination of Cyclamic Acid
Authors: Conacher H B S , O’Brien R C
Published: February 2020

A quantitative GLC technique is presented for the determination of cyclamic acid in soft drinks. The procedure involves GLC analysis of the cyclamic acid after reaction with diazomethane, using methyl stearate as internal standard. Recoveries of known amounts of cyclamic acid added to water and to soft drinks ranged from 90 to 98%. The procedure permits simultaneous determination of cyclamic acid and saccharin.
Gas Chromatography of the Trimethylsilyl Derivatives of Flavanones
Authors: Coffin D E , Dupont J E
Published: February 2020

A procedure was developed for the detection and measurement by gas-liquid chromatography of the 4 flavanones isosakuranetin, naringenin, hesperetin, and eriodictyol as their trimethylsilyl derivatives. The derivatives were prepared by treatment of the flavanones with N,0-bis(trimethylsilyl) acetamide in N,N-dimethylformamide at room temperature. The derivatives of naringenin and hesperetin were separated, detected, and measured by gas-liquid chromatography on a column of OV-101 on Diatoport S with hydrogen flame detection. Isosakuranetin and eriodictyol derivatives could be detected but were not adequately separated by this system. These procedures were applied to the detection of the flavanones derived from orange and grapefruit juices.
Determination of Water in Molasses by Karl Fischer Method
Authors: Kviesitis Boris
Published: February 2020

Successful use of the method depends on several factors, one of which is the size of the sample because it affects the result of the titration. In this study, 2 sizes of cane molasses samples were tested and the results were compared with those from the vacuum oven method. The use of larger samples with or without the addition of surfactant increased the precision of the analysis. It is recommended that the Karl Fischer method for water determination in molasses and sugar sirups be subjected to collaborative study.
Automated Analysis of Sulfamethazine and Procaine Penicillin in Feed Premixes
Authors: Zagar John B , Ascione Peter P , Chrekian George P
Published: February 2020

An automated technique was developed for simultaneously evaluating mixtures of sulfamethazine and procaine penicillin in feed premixes each at levels of 20 g/lb. The system involves the separation of these drugs by an alkaline-chloroform extraction followed by the Bratton-Marshall color determination performed on each resulting phase. Quantitation progresses at a rate of 20 samples or 40 assays/ hr and is accomplished by direct comparison of samples to appropriate standards treated in a like manner.
Variations of Florisil Activity: Method to Increase Retentive Properties and Improve Recovery and Elution Patterns of Insecticides
Authors: Hall Edward T
Published: February 2020

The adsorptive capacity of 10 different lots of commercial Florisil (60-100 mesh) was tested by determining the recovery and elution patterns of 10 chlorinated and 6 organophosphate insecticides. Four lots were regular grade Florisil (calcined at 1200°F) and 6 lots were PR grade Florisil (calcined at 1250°F). All lots were tested as received and tested after washing with hot distilled water and re-igniting at 1250°F for 2.5 hr. Results indicated a wide variation in the activity and retentive properties of the untreated lots. Certain pesticides were not totally removed from the column by the respective eluant and some were irreversibly held on the column and not apparent in other eluants. After the washing and reigniting treatment, all lots of the PR Florisil gave satisfactory recovery and separation in the proper eluants. The lauric acid value was used to determine the quantity of Florisil to be placed on the column.
Herbicidal Carbamates: Extraction, Cleanup, and Gas Chromatographic Determination by Thermionic, Electron Capture, and Flame Photometric Detectors
Authors: Onley John H , Yip George
Published: February 2020

Extraction, cleanup, and gas chromatographic procedures have been developed for the determination of carbamate herbicides in food crops. Each sample is extracted with ethanol or an ethanol-water mixture and then cleaned up on a MgO-cellulose column. Determinations are made by gas chromatography, using thermionic and electron capture detectors; a flame photometric detector may also be used to quantitate and confirm those carbamates containing sulfur. Recoveries from apples, potatoes, alfalfa, corn, and soybeans at fortification levels of 0.01 to 10 ppm exceeded 80%.
Stability of Metallic Ethylene Bisdithiocarbamates in Chopped Kale
Authors: Howard Samuel F , Yip George
Published: February 2020

Chopped kale samples were fortified with maneb, zineb, or Dithane M-22, a maneb formulation. Samples were stored in a freezer or refrigerator and analyzed daily for 3 days. Using the carbon disulfide evolution procedure, the dithiocarbamate content in the samples was determined. Zineb was more stable than maneb or Dithane M-22 in both the frozen and refrigerated state. Immediately upon mixing, there was a loss of about 10% Dithane M-22 and 25% maneb. Freezing the samples prevented further losses.
Residues of Maneb and Ethylene Thiourea on Field-Sprayed Lettuce and Kale
Authors: Yip George , Onley John H , Howard Samuel F
Published: February 2020

Two crops, lettuce and kale, were treated with a maneb formulation at a rate of 2.4 lb active/acre. Samples were harvested at various times after application for residue analysis. The residues determined were maneb and ethylene thiourea (ETU). On lettuce, residues of maneb decreased from 45 to 5 ppm in 15 days. On kale, the decrease was from 90 to 15 ppm in 7 days. With both crops, ETU which was already present in the formulation did not accumulate, but quickly decreased from 0.6 ppm to undetectable amounts after 7 days.
Fading of Aflatoxin Spots on TLC Plates During Fluorescence Densitometry
Authors: Nesheim Stanley
Published: February 2020

Fading of fluorescence of aflatoxin spots on TLC plates has been previously associated with causes such as exposure of plates to UV light, air, heat, and humidity. In this study it was shown that the lamp-cooling effluent from the high intensity xenon lamp light source of a spectrofluorometer TLC plate scanner reduced the fluorescence of aflatoxins B1 and G1 by about 90%; whereas the B2 and G2 fluorescence was reduced by less than 25%. The fading can be prevented by covering the plate with another glass plate.
Micro determination of Nitrogen in Plant Tissues
Authors: Mitchell H L
Published: February 2020

In the semimicro method for nitrogen, the plant sample is digested with C11SO4 or HgO as catalyst in an acid medium, EDTA is added to prevent interference from metals, and the res ulting solution is neutralized to pH 7. Sod ium nitroprusside is added and the color is allowed to develop 1hr ; the absorbance is measured at 625 n m . The proposed method, with either CUSO4 or HgO, is applicable to dry or fresh plant tissues and yields results which are comparable to those obtained with AOAC 2.049-2.051.
Chlortetracycline Residues in Broiler Tissue and Organs
Authors: Katz Stanley E , Fassbender Carol A , Dorfman Donald , Dowling John J
Published: February 2020

Chlortetracycline was fed continuously to chicks at levels of 50–200 g/ton from the age of 1 day to 12 weeks; t h e tissue, blood, and organs were examined for residues. Average muscle tissue concentrations ranged from 0.036 to 0.109 μ/g in the feeding range, blood levels ranged from 0.043 to 0.076 μ/g, liver residues ranged from 0.058 to 0.199 μ/g? a n d kidney residues ranged from 0.377 to 1.147 μ/g- Tissue, blood, and liver residues disappeared 1 day after withdrawal from the medicated feed but measurable levels remained in the kidneys for 3 days. Storage studies of muscle tissues, intestinal analysis, and kidney levels all indicate a reservoir of activity, most probably the epimer form, in the tissue. Cooking, however, converted residues in the tissue to isochlortetracycline which has no known biological activity. Livers, however, retained some 31% activity after preparation.
Infrared Studies of DDT, Structurally Related Halogenated Pesticides, and Some Metabolites
Authors: Chen Jo-Yun T , Dority Roland W
Published: February 2020

Reference IR spectra of 29 purified halogenated pesticides are presented. The spectra were recorded with micro quantities of the purified pesticide compounds to facilitate identification of pesticide residue isolates. The compounds included DDT and related structures. The observed characteristic frequencies are tabulated in correlation tables, and their significance is interpreted in terms of the substituents and of the electromesomeric and mass effects of the substituents. The relevance of these effects to the stability and persistence of this class of pesticides is noted.
Collaborative Study of a Method for the Extraction of Light Filth from Canned Fish
Authors: Dent Russell G
Published: February 2020

Collaborative results are presented for a method proposed for light filth extraction from canned fish packed in water, oil, or vegetable sauces. The method utilizes an acid digestion and a hot mineral oil extraction from an aqueous phase in a Corning percolator. Recoveries are reproducible and filter papers are relatively clean. This method is recommended for adoption as official first action to replace procedure 40.064.
Mass Spectrometry of Volatile Derivatives. V. N-Dialkylnitrosamines
Authors: Saxby M J
Published: February 2020

Twenty-four dialkyl-N-nitrosamines have been studied under electron impact. They exhibit molecular ions which fragment by cleavage at the carbon atom of the longer alkyl chain and the resulting ion then expels the neutral fragment HNO. The molecular ions from many nitrosamines also lose a hydroxyl radical but deuteration experiments have failed to substantiate a general mechanism for this process. Loss of nitric oxide from the molecular ion was not found in any of the derivatives, except methyl ter 1.-butyl nitrosamine.
Screening Method for the Detection of Chlorodibenzo-p-dioxins in the Presence of Chlorobiphenyls, Chloronaphthalenes, and Chlorodibenzofurans
Authors: Williams D T , Blanchfield B J
Published: February 2020

A method has been devised for the detection of chlorodibenzo-p-dioxins in the presence of chlorobiphenyls, chloronaphthalenes, and chlorodibenzofurans. The chlorodibenzo-p-dioxins are chlorinated to octachlorodibenzo-p-dioxin, which is then identified by electron capture gas-liquid chromatography. 2,3,7,8-Tetrachlorodibenzo-p-dioxin has been determined in corn oil at the 1 ppm level.
Study of the Silicic Acid Procedure of Armour and Burke for the Separation of Polychlorinated Biphenyls from DDT and Its Analogs
Authors: Masumoto Herbert T
Published: February 2020

The silicic acid procedure of Armour and Burke for the separation of polychlorinated biphenyls from DDT and its analogs produces an adequate separation of Aroclor 1260. However, the procedure cannot completely separate p,p′-DDE from Aroclors 1221, 1232, 1242, and 1254. Factors causing variable column properties were examined. The 7 hr minimum period for silicic acid activation was found to be inadequate for reproducible water-silicic acid preparations. A 24 hr minimum period is suggested. The use of Celite in column preparation often results in improperly prepared columns and should be eliminated. Nonreproducible columns might also be due to a heterogeneous water-silicic acid adsorbent which is a result of an irregular distribution of water molecules on to the silicic acid particles.
Precision and Accuracy of Infrared Milk Analysis
Authors: Biggs D A
Published: February 2020

Estimates of precision and accuracy of milk analysis by the IR method are reported for comparison studies done at the University of Guelph, the Ontario Central Milk Testing Laboratory in Guelph, the British Columbia Department of Agriculture Laboratory in Vancouver, B.C., and the Dairyman’s Cooperative Creamery Association in Tulare, Calif. The standard reference methods used were: the Mojonnier method for fat, a semimicro Kjeldahl method for protein, a polarimetric method for lactose, the USDA lactometer method for solids-not-fat, and the AOAC method for total solids. Mean differences of 0.01 or less and standard deviations of difference between means of duplicate tests of the order of ±0.03 have been reported for fat, protein, and lactose; whereas, for solids-not-fat or total solids, mean differences have been about 0.015% and standard deviations of difference about ±0.09%. Best results have been obtained when calibrations have been routinely checked with a reference standard method, and have been adjusted when accumulated calibration data showed either the slope or level calibration to be in need of adjustment. Since the IR method essentially reproduces the results which would be obtained by the standard analytical method used for calibration of the IR instrument, significant differences between the results produced by different laboratories with standard methods will cause significant differences between the IR results produced by the same laboratories. This has been substantiated by the results of a collaborative study in which 5 pasteurized homogenized and 5 raw milk samples were analyzed by both standard and reference methods at the above mentioned laboratories and at Ross Laboratories in Columbus, Ohio. Although regression analysis showed that the calibrations at the various laboratories were producing good estimates of the standard values, there nevertheless were statistically significant differences between the mean values produced by these laboratories for both the standard and IR methods. The IR milk analyzer method for the analysis of milk has been adopted as official first action.
Collaborative Study of the Spectrophotometric Determination of Phosphatase Activity in Milk Utilizing a New Alkaline Phosphatase Assay System
Authors: Kleyn D H , Huang C L
Published: February 2020

A quantitative procedure (modified new method) has been studied that employs phenolphthalein monophosphate as the substrate and dialysis of released phenolphthalein followed by subseqvient measurement of the dialysate in a spectrophotometer at 550 nm. Nine collaborators evaluated 6 unknown samples of milk containing various levels of rawmilk, in triplicate, by the modified new method and the Scharer modified spectrophotometric method. Analysis of variance revealed that the random error of the modified new method was almost twice that of the Scharer technique, while the systematic error of the modified new method was only about ¼ that of the latter method. Two-sample charts indicated that the systematic error of the modified new method was less than that of the Scharer method; this was verified by a statistical comparison which showed that the total analytical error was much lower for the modified new method. A linear relationship was found between the 2 methods by 5 of the collaborators; the correlation coefficients ranged from 0.993 to 0.999. Based on these results, the method has been adopted as official first action for the analysis of milk.
Selective Detection of Chlorinated Insecticides in the Presence of Polychlorinated Biphenyls
Authors: Dolan J W , Hall R C , Todd T M
Published: February 2020

A gas chromatographic method for selectively detecting chlorinated insecticides in the presence of polychlorinated hiphenyls is reported. A Coulson electrolytic conductivity detector was modified to allow precise control of furnace temperature and hydrogen reaction gas flow. A furnace temperature of 600°C and a hydrogen flow of 1-2 ml/min were most advantageous for selective detection of chlorinated insecticides in the presence of polychlorinated hiphenyls.
Wet Sieve Analysis of Limestone
Authors: Rexroad Paul R
Published: February 2020

A study of wet sieving vs. dry sieving was made on 47 limestone samples. Fifteen samples showed absolute differences of 5% or more on a U.S. No. 40 sieve when the dry samples were not crushed to break agglomerates. Three samples differed by more than 15%. Crushing “with a hard rubber roller on a hard rubber mat” reduced the absolute difference by 2.9 to 10.3% on the 15 samples. The wet sieving technique has been accepted as an alternative technique for crushing of agglomerates.
Determination of Esters in Alcoholic Beverages
Authors: Coe G R , Baldwin S , Andreasen A A
Published: February 2020

Results are presented on a collaborative study comparing 2 methods for the determination of esters in distilled alcoholic beverages. A previously described colorimetric method was compared with the present official AOAC saponification method, 9.050–9.052. Statistical evaluation of the data shows that the 2 methods are comparable in accuracy and precision. The colorimetric method has been adopted as official first action as an alternative to 9.050–9.052 for the determination of esters in distilled alcoholic beverages.
Collaborative Study of the Determination of Total Lipids in Fish Meal
Authors: Knobl George M , Miller Harry
Published: February 2020

A semimicro method for determining total lipids in fish meal, using a compact extraction apparatus, was subjected to collaborative study. Four fish meals were analyzed for total lipids by 8 collaborators. Per cent lipid content of meals prepared from Canadian herring, Peruvian anchovetta, Atlantic menhaden I, and Atlantic menhaden II were 14.69±0.37, 15.98±0.28, 14.66±0.45, and 10.86±0.26, respectively. In our laboratory, the new extraction technique was also compared with a blender technique. In general, the variation in lipid content within a laboratory, using the extractor, was less than the variation found in our laboratory, using the blender. The semimicro method for the determination of total lipids in fish meal has been adopted as official first action. It is recommended that another collaborative study be conducted, using both the blender and the extractor.
Comparison of Gas Chromatographic Calibration Methods for Analysis of Menadione and Menadione Sodium Bisulfite Content of Pharmaceutical Products
Authors: Shepparid A J , Hubbard W D , Prosser A R
Published: February 2020

A comparative study was made of 2 GLC calibration methods for determining the menadione and menadione sodium bisulfite content of pharmaceuticals. One method utilizes an external standard and the second method makes use of butylated hydroxyanisole as an internal standard. Measurements were made on 8 pure solutions of known concentration of menadione and on 5 pharmaceuticals containing menadione or menadione sodium bisulfite. No significant difference was found between the results obtained by the 2 methods.
Collaborative Study of the Determination of Available Manganese in Fertilizer
Authors: Thorpe Virginia A
Published: February 2020

A collaborative study was conducted to show that the H2SO4-HNO3 digestion in the atomic absorption method for manganese in fertilizer more nearly reflects the available divalent manganese than the HC1 digestion now in use. A method to determine water-soluble forms of manganese was included in the study. Modifications of the HC1 digestion used for total manganese content including available and unavailable forms of manganese (Mn(II) and Mn(IV)) and the H2SO4-HNO3 digestion used for total divalent forms of available manganese were adopted as official first action; the water extraction method was adopted as official first action for water-soluble forms of divalent manganese.
Microbiological Assay of Monensin in Chicken Rations
Authors: Breunig H Latham , Kline Richard M , Bikin H
Published: February 2020

The microbiological plate assay method for monensin in chicken rations reported earlier was submitted in a slightly modified form to 10 collaborating laboratories, along with randomized and coded samples. Other factors in the experiment design were ration types (4 at 2 potency levels) and feed forms (2—meal and pellets). Mean recoveries on 4 ration types were 90.5–96.3% of label over all laboratories and feed forms, while mean recoveries on the 2 feed forms were 96.7% for meal and 89.7% of label for pellets over all laboratories and ration types. The mean recoveries in the 10 laboratories ranged from 78.6 to 119.9% of label, with a median of 93.8%. Only one laboratory was an outlier. There were no significant interactions. The laboratories were uniform with respect to within-laboratory variation. Relative standard deviations of the assay within the laboratories ranged from 3.5 to 12.5% with a median of 6.85%. The microbiological assay method for monensin has been adopted as official first action.
Collaborative Study of a Method for Determining Lead in Plant and Animal Products
Authors: Hoover William L
Published: February 2020

A method for the determination of lead in food products was collaboratively studied. The method involves co-precipitation of lead with strontium sulfate, conversion to carbonate, dissolution in nitric acid, and determination by atomic absorption spectrophotometry. Eight collaborating laboratories reported analytical results for 24 test samples. Results indicated that the systematic error was essentially the same as the random error at the 99% level. Acceptable coefficients of variation were observed. The method has been adopted as official first action.
Synthesis of Chlorobiphenyls Labeled with Deuterium and Chlorine-36
Authors: Hutzinger O , Pothier C , Safe S
Published: February 2020

Four di-, tetra-, and hexachlorobiphenyls labeled with deuterium (>98%) in specific positions have been prepared by selective hydrogenolysis of iodine from chloroiodobiphenyls with lithium aluminum deuteride. 3,3’,4,4’- Tetrachlorobiphenyl (4,4’-36Cl) and 2,2’,4,4’,- 5,5’-hexachlorobiphenyl (4,4’-36Cl) were made by the decomposition of the corresponding chlorobiphenyl diazonium fluoroborates in dimethyl sulfoxide in the presence of ferric chloride-36Cl. The 2 synthetic routes described are models for the preparation of many related compounds because a variety of amino compounds, which are starting materials in the reactions described, are readily available.
Rapid Screening Method for the Determination of Organochlorine Pesticide Residues in Wheat by Electron Capture Gas Chromatography
Authors: Levi Iser , Mazur P B , Nowicki T W
Published: February 2020

A rapid screening method, employing a gas chromatographic technique with electron capture detection, has been developed for t h e analysis of organochlorine pesticide residues in hard red spring wheat. Ground wheat is extracted by ball-milling with an ethyl etherhexane (3 + 97) extractant. After filtration, the extract is cleaned up on a partially deactivated Florisil column, using a single eluting system, ethyl ether-hexane (1 + 99). The eluate i s concentrated before gas chromatographic analysis. Sixteen organochlorine pesticide chemicals were recovered in excess of 80% from wheat samples fortified at 0.010 and 0.200 ppm. Organochlorine pesticide residues were recovered by the rapid method from 18 samples with field-incurred residues as efficiently as by t he Bertuzzi et al. method. Organochlorine pesticide residues were also recovered by t h e rapid method from 4 samples with field-incurred residues and from 2 wheat samples, spiked at 0.500 ppm as efficiently as by the total extraction method of Mumma et al. The rapid method offers a savings in time and solvents over.the Bertuzzi et al. method for the determination of organochlorine pesticide residues in wheat.
A Systematic Approach to Ink Identification
Authors: Brunelle Richard L , Pro Maynard J
Published: February 2020

A systematic approach to identification of writing inks is presented. This approach uses a multiple technique method for analysis of the inks to develop a large number of identifiable points for comparison. Well established methods are used for the analysis of inks, such as thin layer chromatography, spectrophotometry, and gas-liquid chromatography, in addition to traditional methods for comparison which use ultraviolet and infrared light. The inks are identified by comparing the results of the questioned inks with results obtained from a complete library of writing inks maintained by this laboratory. By using the described approach, most inks can be identified with a high degree of certainty.
The Law Enforcement Standards Laboratory
Authors: Mills Robert
Published: February 2020

The primary mission of the Law Enforcement Standards Laboratory (LESL), i.e., the development of national voluntary standards for law enforcement hardware, is described. Emphasis is given to LESL projects of interest to forensic scientists, such as blood and breathalcohol testers and evidence gathering kits. Plans for future work and studies on the need to develop recommended practices for test procedures, certilied reference materials, and standard reference data for use in forensic laboratories are discussed.