bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectroanalytical Parameters of Fungal Metabolites. II. Luminescence of Griseofulvin
Authors: Neely W C , Mcduffie J R
Published: February 2020

I n this study of the luminescence characteristics of griseofulvin we report corrected ambient temperature fluorescence excitation and emission spectra. The uncorrected fluorescence excitation and emission spectra on thin layer chromatographic plates are also reported. The quantum efficiency of fluorescence is calculated to be 0.108 and the mean phosphorescence lifetime determined to be 0.11 sec. The fluorescence lifetime is calculated to be 0.663 nsec. It appears t h a t phosphorescence emission may be the most sensitive spectral parameter; measurable phosphorescence can be obtained from solutions as dilute as 10-8M. No photodecomposition is apparent under reasonable conditions of light exposure.
Quantitative Fluorodensitometric Measurement of Aflatoxin B1 with a Flying-Spot Densitometer. II. Comparative Study of B1 Measurements in Spiked and Naturally Contaminated Peanut Products
Authors: Beljaars P R , Fabry F H M , Pickott M M A , Peeters M J
Published: February 2020

Peanut butter extracts and samples spiked with 5-40 μg anatoxin B1/kg were analyzed, together with naturally contaminated peanut products, by 3 extraction procedures: the official Dutch method (KB), he Liem et al. method (methanol), and the IUPAC method. The last procedure was selected as a reference method, since it has international application. KB extracts were separated on silica gel G plates with a mixture of chloroform-acetone (90 + 10), whereas IUPAC extracts were separated similarly on MN-G-HR plates. Methanol extracts were resolved on silica gel II plates, using chloroform-trichloroethylene-n-amyl alcohol-formic acid (80 + 15 + 4 + 1) as the developing solvent. After development, plates were scanned with a reflectance flying-spot densitometer. With such techniques, average recoveries for spiked peanut butter extracts ranged from 99 to 105%, with variation values of 11-12%. Recovery values of 69% (KB method) and 84% (methanol and IUPAC methods) were obtained for spiked peanut butter samples. Coefficients of variation ranged from 13 to 15% for fluorodensitometric measurements. Innaturally contaminated peanuts and peanut products , precision values were 13.6% for fluorodensitometric measurements compared to 36% for visual estimations . Both the methanol and IUPAC methods yield extracts suitable for densitometric analysis after spotting on TLC plates; the analytical results obtained are comparable. Extracts from the KB method contained more interfering fluorescent material than the other 2 methods
Determination of Submicrogram Amounts of Mercury in Standard Reference Materials by Flameless Atomic Absorption Spectrometry
Authors: Rains Theodore C , Menis Oscar
Published: February 2020

In a study of the flameless atomic absorption method for the determination of nanogram amounts of mercury in organic materials, the technique was improved to provide greater precision and accuracy. The loss of mercury during the digestion of organic materials with nitric, sulfuric, and perchloric acids is prevented by controlled heating and a packed refluxing column. The reduction and absorption system was simplified by using a heated absorption cell which alleviates the interference of volatile vapors. This method has been applied to the determination of mercury in NBS Standard Reference Materials of orchard leaves, liver, and coal, and the results were compared with results obtained with 2 other analytical methods.
Microbiological Assay of Oxytetracycline in Liquid Supplements
Authors: Clarke Donald W
Published: February 2020

The extraction procedure of the official final action method for the determination of oxytetracycline in dry feeds, 38.208–38.213, has been modified for the analysis of liquid supplements. Ten g samples were extracted with 50 ml acid-methanol and diluted to 100 ml with the same solvent. Aliquots of the extract prepared according to the modified extraction procedure were assayed by the present official method and gave an average recovery of 100.6% and a coefficient of variation of 6.2% at a medication level of 500 mg/lb. Assays performed on liquid supplements containing oxytetracycline stored for an average of 26 days at 37 and 21°C, and for 37 days at – 4°C showed potency retentions of 21, 80, and 97%, respectively, indicating a need for low-temperature storage prior to analysis.
Sulfuric Acid for the Cleanup of Animal Tissues for Analysis of Acid-Stable Chlorinated Hydrocarbon Residues
Authors: Murphy Philip G
Published: February 2020

Biological substances interfering with pesticide residue analysis are removed from hexane extracts of animal tissues by shaking them with concentrated H2SO4. Recoveries are reported for several chlorinated hydrocarbon pesticides and polychlorinated biphenyls (PCB) from fish extracts. This treatment destroys dieldrin and organophosphate pesticides, but affords a rapid, efficient, and economical cleanup of animal tissues for the analysis of DDT, PCB, and other acid-stable chlorinated hydrocarbon residues.
Application of a Laboratory Analog-Digital Computer System to Data Acquisition and Reduction for Quantitative Analyses
Authors: John Matt K , Van Laerhoven Cornelis J
Published: February 2020

A flexible, general purpose program for a laboratory data acquisition and reduction system employing a minicomputer for off-line processing of digitized data readings from electroanalytical instrumentation was developed. Instrument data from the on-line operation of a hard-wired analog-to-digital data acquisition subsystem in conjunction with an atomic absorption instrument, a colorimeter, or a pH/millivolt meter for speeific-ion electrode determinations, are transformed into concentration units by using a linear interpolation method. The relationship between instrument measurements and quantitative data is approximated by several straight-line segments between the graphical coordinates associated with each of the reference standards analyzed. The coordinates are determined by calibrating readings and known concentrations. Routines are included to edit incorrect raw readings and to make corrections to compensate for unavoidable deviations from standard analytical procedure. The FOCAL-8 language program, therefore, permits unattended processing of sequentially read paper tape input. The results punched on paper tape are easily transferred to a large computer for more sophisticated data analysis and storage.
Emission Photometric Determination of Boron in Unboronated Fertilizers, Using the Nitrous Oxide-Hydrogen Flame
Authors: Pickett Edward E , Pau Jimmy C-M
Published: February 2020

The analysis of boronated fertilizers by extraction of acid-soluble boron with 2-ethyl-l,3-hexanediol in chloroform, with determination of boron by emission flame photometry, has been modified so that it may be applied to unboronated fertilizers. The very hot but non-reducing nitrous oxide-hydrogen flame provides a detection limit of 0.05 ppm in the extract or 0.5 ppm in the sample. Fluoride is the only major interference and this is eliminated by addition of zirconium ions. The range of boron content found in 8 samples of mixed fertilizers was 28.8 to 202 ppm.
Gas-Liquid Chromatographic Determination of Chloroanisoles in Soy Oil and Other Vegetable Oils
Authors: Williams D T
Published: February 2020

A method for the detection of chloroanisoles in soy oil utilizes partitioning between petroleum ether and acetonitrile followed by column chromatography on activated alumina. The eluate from the column, after treatment with concentrated sulfuric acid, is analyzed by electron capture gas-liquid chromatography. Recoveries from a 2 g sample of soy oil fortified at 0.01–1.0 ppm were 85–103% for pentachloroanisole, 82–99% for 2,3,4,6-tetrachloroanisole, and 75–96% for 2,4,6-trichloroanisole. Recoveries from samples fortified at 0.1–1.0 ppm were 83–99% for 2,4,5-trichloroanisole, 67–85% for 2,6-dichloroanisole, and 78–99% for 2,4-dichloroanisole.
Gas-Liquid Chromatographic Determination of Methyl Isothiocyanate in Soils
Authors: Sirons George J
Published: February 2020

Residues of methyl isothiocyanate in soils are extracted with diethyl ether containing 5% ethanol, concentrated in a Kuderna-Danish concentrator, and subjected to gas-liquid chromatography without further cleanup. A 6% Carbowax 20M column is used in conjunction with either conductivity (nitrogen mode) or flame photometric (sulfur mode) detection systems. The method is rapid and capable of determining methyl isothiocyanate residues in soils at a level as low as 0.01 ppm.
Oxytetracycline Residues in Tissue, Organs, and Eggs of Poultry Fed Supplemented Rations
Authors: Katz Stanley E , Fassbender Carol A , Dowling John J
Published: February 2020

Oxytetracycline was fed continuously to broilers at 25 to 200 g/ton from the age of 1 day to 11 weeks. Residues in the muscle tissue at 11 weeks ranged from trace quantities at 25 g/ton to 0.20 μg/g at 200 g/ton; liver residues ranged from not detectable to 0.29 μg/g at 200 g/ton; kidney levels ranged from 0.09 to 0.78 μg/g at 200 g/ton. Tissue, blood, liver, kidney, and intestinal contents were negative 24 hr after withdrawal from the drug. Cooking destroyed all residues in muscle tissue but livers retained 50% of the uncooked levels. Eggs from hens fed up to 400 g/ton contained no measurable residues.
Comparative Studies of Thin Layer Chromatographic Systems for the Separation and Identification of Photoalteration Products of Parathion
Authors: Joiner Ronald L , Baetcke Karl P
Published: February 2020

Twelve thin layer chromatographic systems were compared for the separation of photoalteration products of parathion. Rf values for each component in each system are presented. Infrared spectra confirmed the identity of separated components. The following 4 systems were designated superior and gave excellent separation of the components: petroleum ether-ethyl ether-glacial acetic acid (80+15+5 and 50+45+5), methanol-chloroform-ammonium hydroxide (24+75+3.5), and methanol-chloroform-petroleum ether (10+20+70).
Collaborative Study of the Ultraviolet Spectrophotometric and Gas-Liquid Chromatographic Methods for the Determination of Trifluralin and Benefin in Formulations
Authors: Hambleton Larry G
Published: February 2020

Fourteen collaborators participated in a study of an ultraviolet (UV) Spectrophotometric and a gas-liquid (GLC) method for the determination of trifluralin and benefin. In the UV method, trifluralin or benefin is extracted from the solid carrier or dissolved in n-hexane, if the formulation is liquid, purified by chromatography on Florisil, and determined by UV spectrometry at 376 nm. In the GLC method, the compound is extracted from the solid carrier or dissolved in acetone, if liquid, and determined by flame ionization GLC, using a column containing 5% DC-200 on 80–100 mesh Chromosorb W (HP). A statistical evaluation of the data by the technique of closely matched pairs is presented. The data show good correlation between the 2 methods and the methods seem to be reasonably accurate and precise. The ultraviolet and gas chromatographic methods have been adopted as official first action.
Collaborative Study of a Gravimetric Method for Mercury in Formulations Containing Chlorinated Pesticides
Authors: Launer James E
Published: February 2020

A gravimetric method for mercury was modified and collaboratively studied with formulations containing ~6% phenylmercuric urea and ~7% captan in one test pair and ~2% phenylmercuric urea and 30% lindane in another test pair. Mercury is determined by precipitation and weighing cupric propylene mercury iodide (Cu pn2HgI4), following refluxing with dilute HI-H2SO4 solution containing I2. Single determinations on 4 samples by 11 collaborators showed that the standard deviation estimation of random error was 0.063 for the captan pair and 0.034 for the lindane pair. Standard deviation estimates of systematic error were 0.061 and 0.013, respectively. In the preliminary study, the method showed close agreement with other accepted methods for 15 formulations. Lindane, captan, dieldrin, heptachlor, and zineb do not interfere; however, the method is not applicable to chloro- or nitrophenolic compounds nor to materials not decomposed by the digestion mixture. The method has been adopted as official first action.
Collaborative Study of a Gas-Liquid Chromatographic Method for the Analysis of Ametryne, Prometone, and Terbutryn
Authors: Hofberg Arthur H , Murphy Robert T
Published: February 2020

A gas chromatographic method for the determination of ametryne and terbutryn in wettable powder formulations containing about 80% active ingredient and prometone in liquid formulations containing about 25% active ingredient was collaboratively studied, using a matched pair scheme. The ametryne was extracted from the powder with chloroform containing dieldrin as an internal standard and chromatographed on Carbowax 20M, using a flame ionization detector; the same method was used for terbutryn. The sample containing prometone was dissolved in chloroform containing dieldrin and chromatographed in the same manner. Two samples of each pesticide were analyzed, using peak height measurements, with the following results: ametryne (14 collaborators)—1.63% overall coefficient of variation, 0.68% coefficient of variation for the random error, and 1.05% systematic error; prometone (15 collaborators)—2.27, 1.47, and 1.21%; and terbutryn (15 collaborators)—0.95, 0.51, and 0.56%, respectively. The method has been adopted as official first action.
Detection of Turmeric in Foods by Rapid Fluorometric Method and by Improved Spot Test
Authors: Karasz Albert B , De Cocco Frank , Bokus Linda
Published: February 2020

The rapid test for turmeric is based on the fluorescence of curcumin, the principal pigment of turmeric. In a water-saturated n-butanol solution, its excitation maximum is 435 nm and the emission maximum is 520 nm. In the test described, which was applied to pickles, salad dressings, and baked goods, a sample is shaken with the butanol solvent and the filtered extract is scanned for a 520 nm peak on a spectrophotofluorometer that has been adjusted to give 100% scale deflection for a standard curcumin solution. Extracts of pickles and salad dressings are scanned directly. Extracts of enriched baked goods are treated to remove riboflavin fluorescence by partitioning both riboflavin and curcumin from butanol into a solution of 0.1N NaOH-15% NaCl, acidifying the latter with CH3COOH, reducing the riboflavin with Na2S2O4, and reextracting curcumin from acid solution into butanol for fluorometric scanning. No interference is caused by annatto, carotene, tartrazine, or egg yolk solids. A spot test may be performed on the butanol extract. The solution is evaporated to dryness, the residue is dissolved in a few drops of ethanol, and the spot test is performed with a boric acid reagent of considerably improved sensitivity.
Collaborative Study of a Colorimetric Determination of Benztropine Mesylate in Tablets and Injections
Authors: Stricklin Marshall C
Published: February 2020

A collaborative study was conducted on simulated tablet and injection preparations at 2 concentration levels each and a 20 tablet composite of a tablet simulating presently marketed dosage forms of benztropine mesylate. Analysis involves the extraction of benztropine from 0.2N H2SO4 with bromophenol blue in CHCl3. Absorbance of the dye complex formed is measured at about 410 nm. Average recoveries and standard deviations submitted were: 98.9±2.54 and 99.2±2.58, 100.1±2.78 and 100.0±2.19, and 100.1±2.23%, respectively. The method has been adopted as official first action.
Collaborative Study of the Recovery and Gas Chromatographic Quantitation of Polychlorinated Biphenyls in Chicken Fat and Polychlorinated Biphenyl–DDT Combinations in Fish
Authors: Sawyer Leon D
Published: February 2020

Nine laboratories collaborated on the analyses of PCBs in chicken fat and DDT-PCB combinations in fish. Existing AOAC multipesticide methodology with GLC quantitation was employed. One solution containing a mixture of Aroclors 1254 and 1260 was analyzed by GLC only. The fish samples were subjected to a published silicic acid procedure for separating the DDT-PCB mixtures. The DDT analogs were quantitated before and after the separation. The PCB content was quantitated by total peak height and total area comparisons against appropriate Aroclor(s), using electron capture GLC, and additionally in 6 laboratories by total area comparisons, using halogen-specific detection. The electron capture GLC data demonstrated better accuracy and precision. The following PCB recoveries were obtained by using total peak height comparisons: 5 ppm mixed Aroclor solution, 100±4%; 8 ppm Aroclor 1242-fortified chicken fat, 101±13%; 7.5 ppm Aroclor 1248-fortified chicken fat, 96±9%; incurred Aroclor 1242 chicken fat, 9.2 ppm±8%; 6 ppm Aroclor 1254-fortified fish, 75±14%; 6 ppm Aroclor 1260-fortified fish, 75±15%; and an environmentally incurred residue in fish, 4.5 ppm±20%. The 2 Aroclor-fortified fish samples were concurrently spiked with the p,p′-isomers of DDE, TDE, and DDT at levels of 4, 1, and 3 ppm, respectively. After silicic acid separation the combined recoveries for these 2 samples were: DDE, 86±13%; TDE, 89±20%; and DDT, 84±17%. Environmentally incurred-DDT residues were recovered at 4.1 ppm±14% for p,p′-DDE, 0.7 ppm±24% for o,p′-DDT, and 2.7 ppm±17% for p,p′-DDT. The DDT values calculated before the silicic acid separation compared favorably with those summarized. The multiresidue method for chlorinated pesticides, 29.001–29.027, has been adopted official first action to include polychlorinated biphenyls in poultry fat and fish.
Modifications of the Technique for Differentiating Cultures Isolated by the Official AOAC Salmonella Method
Authors: Poelma Paul L , Romero Aida
Published: February 2020

Modifications are suggested for the official AOAC Salmonella method, 41.024–41.040, by which all colonies picked from selective plates are subcultured in both triple sugar and lysine iron agars. The techniques will detect Salmonella and Arizona cultures which might have been discarded. The revisions have been incorporated into the official method.
Modified Method for the Determination of Mycotoxins in Cocoa Beans
Authors: Scott Peter M
Published: February 2020

Method 26.026–26.030 was modified for the analysis of cocoa beans for aflatoxins by inclusion of 3% silver nitrate solution in the extraction solvent mixture. Recoveries of aflatoxins and ochratoxin A added at levels of 5–45 and 20–300 μg/kg, respectively, were satisfactory.
Collaborative Study of Acid-Detergent Fiber and Lignin
Authors: Van Soest Peter J
Published: February 2020

A second collaborative study on acid-detergent fiber and lignin has been completed involving 10 laboratories and 6 samples including timothy, alfalfa, soybean meal, barley straw, orchardgrass, and wheat straw. Results from 7 laboratories appeared normal according to the Youden collaborative test and yielded a mean duplicate error of 0.40±0.31, a standard error between laboratories of 0.40, and a coefficient of variation of 1.02%. The duplicate error for lignin was 0.23±0.31, the standard error between laboratories, 0.28, and the coefficient of variation, 4.26%. Results indicate problems with filtering, handling fritted glass crucibles in a uniform weighing procedure, and reliably preparing asbestos used in the preparation of lignin. Modifications of the previously published method include reduction of sample size to 1 g, elimination of the use of decalin, rigorous definition of filtration and weighing procedures, use of P2O5 or Mg(ClO4)2 as desiccant, and determination of a lignin blank. Problems in filtration can be overcome by not using more vacuum than is necessary, making all additions with vacuum off, and allowing 15–30 sec settling before applying suction. The modified acid-detergent fiber and lignin method has been adopted as official first action.
Improved Method for the Thin Layer Chromatographic Determination of Patulin in Apple Juice
Authors: Scott Peter M , Kennedy Barry P C
Published: February 2020

Apple juice from a freshly opened container is extracted 3 times with ethyl acetate. The extract is dried, concentrated, diluted with benzene, and added to a silica gel column. Patulin is eluted by benzene-ethyl acetate (75+25) and detected by thin layer chromatography, using a 3-methyl-2-benzothiazolinone hydrazone hydrochloride solution as the spray reagent. Satisfactory recoveries were obtained for patulin added to apple juice at levels of 25–400 μg/L.
Analysis of Ochratoxins A and B and Their Esters in Barley, Using Partition and Thin Layer Chromatography. I. Development of the Method
Authors: Nesheim Stanley , Hardin Nicole F , Francis Octave J , Langham William S
Published: February 2020

A convenient, specific, rapid method, developed for the determination of ochratoxin in barley, involves initial extraction of the sample with water-chloroform (1+9), followed by chromatography of the extract on an aqueous sodium bicarbonate-diatomaceous earth column. The ochratoxin esters are removed from the column with hexane-chloroform. Elution of the column with formic acid-chloroform (1+99) yields ochratoxins A and B. The ochratoxin esters are purified further on an aqueous sodium bicarbonate-methanol-diatomaceous earth column. The extracts are then quantitated on TLC plates by measuring fluorescence intensity. The presence of ochratoxins A and B is confirmed through formation of the corresponding ethyl ester derivatives. In an intralaboratory study, in which samples spiked at 25, 50, and 100 μg/kg levels were analyzed by 4 analysts, the average recovery for ochratoxin A was 81.2% with a lower detection limit of 12 μg/kg.
Prevention of Selenium Interference with Measurement of Phosphate as Its Molybdenum (V–VI) Complex
Authors: Milham Paul J , Short Colin C
Published: February 2020

Selenium used as a catalyst in Kjeldahl digests of plant samples was found to interfere with an automated molybdenum blue technique for determination of phosphate. Interference was prevented by formation of selenocyanate in the presence of excess cyanide. No modification of the apparatus was required and the rate of analysis was unchanged from 40 samples/hr. Reproducibility of the modified technique was good and results were not significantly different (P = 0.01) from those obtained by a manual molybdovanadate procedure.
Collaborative Study of the Microanalytical Determination of Phosphorus in Organic Compounds
Authors: Lalancette Roger A , Steyermark Al , Lee Ruth Ann , Lukaszewski Donna M
Published: February 2020

Sixteen collaborators participated in the study of the determination of phosphorus in organic compounds. Two samples were analyzed by the methods currently in use in the collaborators’ respective laboratories. Samples were combusted by oxygen flask, peroxide fusion, and wet digestion with acid(s). The resulting phosphoric acid was determined either gravimetrically, colorimetrically by the heteropoly blue method, or colorimetrically by the molybdenum yellow method. The various combustion methods were not compared, since there were not enough data to warrant this. The determinative steps were compared, but the data showed no significant difference in either precision or accuracy for any variation. A statistical evaluation of the data showed that the overall mean for the colorimetric heteropoly blue determination of triphenylphosphine (11.81% P) for 4 collaborators is 11.72%; for the colorimetric molybdenum yellow determination for 5 collaborators, 11.70%; and for the gravimetric determination for 3 collaborators, 11.93%. For phenylmethylphosphinic acid (19.97% P), the corresponding values are 19.64, 19.80, and 19.95%.
Voice Identification with the Aid of Spectrographic Analysis
Authors: Nash Ernest W
Published: February 2020

The human voice, as an instrument of crime, is used more often than a weapon and automobile combined. Some crimes are committed by the voice alone; therefore, to be able to identify a speaker by his voice is a very desirable goal in the fight against crime. However, desire has been somewhat hindered by the lack of technology and instrumentation. The use of spectrograms (voiceprints) to assist the expert in making an objective evaluation of the voices in question is discussed. The scientific reason for accepting the identification of a speaker’s voice is the uniqueness of man. Therefore, if a unique person uses unique physiological body parts to produce the sounds of speech, it logically follows that sound will also be unique. By the visual examination of the spectrographic analysis, a trained expert is able to compare the uniqueness.
Method for Differentiating Optical Isomers of Amphetamine by the Simple and Direct Examination of Microcrystals in Gold Chloride Solution
Authors: Clark Jack Hylton
Published: February 2020

Although it has been asserted and generally accepted that d- and l-amphetamine cannot be distinguished by the simple, direct examination of their microcrystal forms, using ordinary light microscopy, a method of observation is described that will easily result in just such a determination. The d- and l-isomers may be distinguished because of their right- or left-oriented, overlapped crystal formations, in a drop-side-up position of the slide.
Infrared Spectrophotometric Analysis of Aldicarb Formulations
Authors: McDermott William H
Published: February 2020

The infrared method described for the assay of aldicarb formulations measures the carbamate carbonyl absorption band at 5.75 μm after extraction with methylene chloride in a Soxhlet extractor. An average recovery of 100.2% was obtained on laboratory-prepared simulated formulations. The standard deviation on repeatability studies on 2 formulations was ±0.2% at the 10% level. The coefficient of variation was ±2%.
Automated Nitrogen Method for Feeds
Authors: Gehrke Charles W , Wall Larry L , Absheer Joseph S
Published: February 2020

A totally automated method for the determination of nitrogen in feeds has been developed. The apparatus consists of Technicon Auto-Analyzer modules. The SOLIDprep Sampler II has been interfaced with the continuous digestor to provide complete solubilization and digestion of dry samples of feed, grain, and forage materials. Hydrogen peroxide is used as an aid for the wet digestion in the continuous digestor. Mercury, selenium, or copper metal catalysts were not effective for increasing the recovery of nitrogen during the continuous digestion. Nitrogen recoveries of 88–90%, relative to ammonium sulfate, have been obtained on several materials, i.e., corn grain, wheat, barley, rice, alfalfa, fescue, mixed feeds, and feed concentrates. The recoveries from these materials average about 100±2% when an empirical standard, soy hydrolysate, is used. The system operates at 20 samples/hr and has provided precise and accurate nitrogen analyses on collaborative samples. Other laboratories cooperated with us in evaluating the method by providing representative samples and their Kjeldahl analyses. This method provides a significant reduction in the labor required for large numbers of nitrogen analyses in feeds.
Aflatoxin M1 in Milk: Evaluation of Methods
Authors: Stubblefield Robert D , Shannon Gail M , Shotwell Odette L
Published: February 2020

Six published methods for the determination of aflatoxin M1 in liquid and powdered milk were compared because a quantitative assay sensitive to 0.1 μg/L was needed for routine analysis. Each method was tested with both spiked and naturally contaminated samples at levels of 0.1, 0.5, and 1 μg/L or 1, 5, and 10 μg/kg; recoveries of M1 were determined. Data revealed that 2 methods, one for liquid milk and one for powdered milk, had the desired sensitivity and recoveries. In the liquid milk method, M1 is extracted and milk protein is precipitated simultaneously with methanol-water (4+1); in the powdered milk method, M1 is extracted with acetone-water (70+30) and milk protein is then precipitated with a lead acetate solution. Both methods remove fats from the aqueous acetone or methanol solutions with hexane before partition of M1 into chloroform. Aflatoxin M1 is determined by thin layer chromatography of the chloroform extracts and either visual or densitometric measurement of mycotoxin on thin layer plates. Modifications were made to simplify the methods and to reduce the time required to complete the assays.
Evaluation of the Response of Dugesia tigrina to Aflatoxin B1
Authors: Llewellyn Gerald C
Published: February 2020

Groups of brown planaria, Dugesia tigrina, were exposed to varying concentrations of aflatoxin B1. Whole animals maintained in 3.125 μg/ml of toxic solution show ed 50% lethality in 2 days; 1.562 μg/ml required 4 days; 0.781 μg/ml required 7 days; and 0.312 μg/ml required 15 days. Even greater lethal responses occurred when cut portions of planaria were exposed to the toxin, with the head sections in all concentrations showing higher levels of lethality than the tail sections. Regeneration of excised heads and tails was inhibited in 3.125 μg/ml medium; minimal regeneration occurred in 1.562 and 0.781 μg/ml environments. D. tigrina, exposed to concentration levels of 0.312 and 0.156 μg/ml of aflatoxin B1 in spring water, regenerated head and tail portions in a normal manner. No gross pathological abnormalities were observed in any regenerated tissue. The lethal response to low concentrations of the toxin suggests that the head portion of D. tigrina is one of the more sensitive organisms to aflatoxin B1.
Determination of Soluble Solids in Roasted Coffee
Authors: Vree Pieter H , Yeransian James A
Published: February 2020

Six laboratories participated in a study of the determination of soluble solids in 9 samples of roasted and ground coffee by 3 methods. In a previous report the reproducibility of the Navellier method and of the method used by the European Decaffeination Association (EDA) was found to be comparable to the current AOAC method. Interlaboratory comparisons show better agreement for the Navellier and EDA methods, with somewhat higher values than the AOAC method. The EDA method has been adopted as official first action to replace method 15.012, which was repealed, official first action.
Collaborative Study of Rapid Fat Determination in Meat and Meat Products by Modification of the AOAC Method
Authors: Pettinati Julio D , Swift Clifton E , Cohen Edward H
Published: February 2020

The rapid method for fat determination reported by this laboratory has been evaluated by 10 collaborating laboratories in a comparison with the AOAC method. The method is similar to the official method except that a 3–4 g sample of meat or meat product is dried in an open extraction thimble for 30 min at 125°C and extracted with ethyl ether for 45 min at maximum reflux, and fat content is determined gravimetrically after complete removal of solvent from the extract. Collaborators performed 6 replicate analyses on samples of ground beef, frankfurters, and fresh pork sausage by both methods. A statistical treatment of the results showed that fat contents determined by the modified method agreed with those obtained by the official method. The expected standard deviation, se, averaged for the 3 types of meat product, was ±0.83% fat which is 1.5 times the value obtained by the official method, ±0.56% fat.
Identification of Drugs by Chemical Ionization Mass Spectroscopy
Authors: Saferstein Richard , Chao Jew-Ming
Published: February 2020

Methods of identifying drugs by chemical ionization (Cl) mass spectroscopy have been investigated. This type of ionization is accomplished by the reaction of the drug with either ionized gaseous methane or isobutane. The resulting spectrum is less complex than that produced by conventional mass spectroscopy and usually results in the formation of a molecular ion plus one (M + 1). The isobutane CI spectra of 62 commonly abused drugs were determined. The mechanism for the formation of fragmentation ions is discussed.
Recovery of Arsenic by Dry Ashing from Animal Tissue Fortified With Organoarsenicals or Arsenic Trioxide
Authors: George Glenn M , Frahm Larry J , Patrick McDonnell J
Published: February 2020

A study was conducted to establish whether or not arsenic recovery from animal tissue is independent of arsenic source. Control chicken liver and kidney tissues were fortified with 1.0 or 2.0 ppm arsenic from arsenic trioxide, roxarsone, arsanilic acid, nitarsone, or carbarsone. The tissue samples were dry ashed and total arsenic was determined colorimetrically. Arsenic recovery for the organoarsenical-fortified tissue samples is essentially complete for all drugs tested. Mean recoveries ranged from 98 to 109% of the theoretical amount expected.
Gas-Liquid Chromatographic Determination of Rotenone and Deguelin in Plant Extracts and Commercial Insecticides
Authors: Delfel Norman E
Published: February 2020

Retention times on 3% methyl silicone in glass columns at 160°C were 0.85 and 1.39, respectively, for deguelin and stigmasterol acetate, the internal standard; and flame ionization detector responses were 1.00 and 1.47, respectively, compared to rotenone as 1.00 in both cases. Rotenolone, when present, interfered with the determination of deguelin. Rotenoid extracts from Derris elliptica and Lonchocarpus nicou roots lacked other interfering materials. Tephrosia vogelii leaflets contained fat-soluble contaminants that were minimized by using acetonitrile for extraction and by subsequent partitioning with hexane. When the GLC assay was applied to commercial samples, rotenone results were comparable to label values in 2 samples and rotenoid oxidation products were detected in 2 others. The precision of GLC was ±4.1%, and the results agreed with those by thin layer densitometry (TLD) within 2.1% for rotenone and 2.9% for deguelin. A minor improvement of TLD for analysis of T. vogelii extracts is also described.
Holst Filtration Apparatus for Van Soest Detergent Fiber Analyses
Authors: Holst David O
Published: February 2020

New filtration equipment was developed to improve the acid-detergent method of fiber fractionation. This apparatus incorporates a vacuum manifold with an air metering device that provides the operator very precise control over the partial vacuum, permitting a very gradual change in vacuum level as needed for proper filtration. The partial pressure is provided by a water aspirator. A hot water jacket permits a continuous flow of hot water around the sample during the filtering process to keep the sample hot. This speeds filtering on practically all samples and is essential for reliable results on samples high in carbohydrates and salts. As a result of this new filtration equipment we do not need asbestos for a filter aid. This eliminates the need for duplicate acid-detergent fiber analyses when using 72% H2SO4 for the cellulose and lignin determinations. Six independent analyses were performed on each of 9 samples (3 feces, 3 orts, and 3 feeds) for the determination of acid-detergent fiber and its constituents. The average maximum differences for these analyses indicate that this filtration apparatus and the method are reproducible and have reduced the filtration time from several hours, on some samples, to 15 min.
Nitrate Determination by a Modified Conway Microdiffusion Method
Authors: Stanford George , Carter John N , Simpson Elmer C , Schwaninger Daniel E
Published: February 2020

The proposed modified Conway microdiffusion method provides for consecutive determinations of NH4- and NO3-N in a given aliquot of soil extract. Analyses of primary nitrate standards showed essentially complete recovery in the range of 1 to 20 ppm NO3-N (4 to 80 μg N/aliquot). Results for (NH4 + NO3)-Ν and NO3-N in soil extracts are comparable to those obtained, respectively, by macrodistillation with Devarda’s alloy and by the phenoldisulfonic acid colorimetric method. The method is rapid and suitable for routine analyses of soil extracts, the equipment is inexpensive, and no interferences are apparent.
Comparison of Two Methods for the Analysis of Pigmenting Xanthophylls in Dried Plant Materials
Authors: Livingston Arvin L , Knowles Richard E , Kohler George O
Published: February 2020

A previously reported procedure for carotene and non-epoxide xanthophyll (NEX) has been modified for the analyses of dried plant materials and mixed feeds, including those which contain xanthophyll esters. The method employs an ambient temperature extraction and saponification technique which permits rapid analyses of carotenoid pigment sources, including dehydrated alfalfa, grass, corn gluten meal, marigold petal meal, and mixed feeds containing these materials. The results were compared with those by the official first action modification of 39.018–39.023 for carotene and xanthophyll in these materials. The reported method gave the same or significantly higher analyses (p≤0.01 or 0.05) for corn, marigold, and one of the alfalfa meals but lower analyses for the grass meal tested. In only 2 of 10 cases were the variances between methods significantly different (p≤0.01 or 0.05), and in both cases the AOAC method gave the lower variance.
Analysis and Chemical Confirmation of Citrinin in Barley
Authors: Hald Benedicte , Krogh Palle
Published: February 2020

A method is described for the quantitative estimation of citrinin in barley by extraction of acidified grain with chloroform. After filtration, the citrinin concentration is estimated visually or densitometrically, using quantitative TLC, by comparison with a citrinin standard. The method will precisely determine concentrations of 0.5 ppm, with a lower limit of detection of about 0.2 ppm. A chemical confirmatory test involving formation of the acetate of citrinin is also described.
Atomic Absorption Spectrophotometric Determination of Dibutyltin Dilaurate in Finished Feeds
Authors: George Glenn M , Albrecht Marven A , Frahm Larry J , Patrick McDonnell J
Published: February 2020

Dibutyltin dilaurate is extracted from finished feed with warm chloroform. The chloroform extract is filtered and a 25 ml aliquot is concentrated in the presence of methanol until all traces of chloroform are removed. The methanol solution is diluted and feed interferences are removed by filtration. The filtered solution is aspirated into an atomic absorption spectrophotometer with a triple-slot burner head, using an air-acetylene flame. The instrument response to tin at 286.3 nm is recorded. Essentially theoretical recovery (100.5— 101.9%) has been obtained for tin in laboratory-mixed feeds.
Simplex Optimized J-Acid Method for the Determination of Formaldehyde
Authors: Czech Fred P
Published: February 2020

This paper is the first in a number of didactic reports on the application of simplex optimization to analytical methods and instruments. The use of simplex optimization allows rapid determination of the best conditions for analytical purposes. Some basic concepts used in simplex optimization operations are introduced, described, and exemplified. A rapid and highly sensitive method for the colorimetric analysis of formaldehyde via J-acid is derived by means of simplex optimization. The method is over 5 times as sensitive as the original J-acid procedure and almost 10% more sensitive than the simplex optimized chromotropic acid procedure. The average relative standard deviation is about ±1.6%. The limit of detectability is estimated to be 70 ppb.
Determination of Carbon Dioxide in Cucumber Brines
Authors: Fleming Henry P , Thompson Roger L , Etchells JOHN L
Published: February 2020

A simple, accurate method for determining carbon dioxide in fermenting cucumber brines is described. The method involves distillation of carbon dioxide from the acidified brine into standardized sodium hydroxide inside a closed jar. The sample is injected by a syringe and needle through a rubber serum stopper placed in the jar cap, into an acid solution. A small vial of sodium hydroxide placed inside the jar traps the carbon dioxide as it distills from the acidified solution. After being held in the jar 24 hr at 37°C, the vial is removed; the remaining base is titrated to the phenolphthalein end point with standardized hydrochloric acid. Advantages of the method include a limited working time, minimized loss of carbon dioxide during analysis, and a relatively small sample size.
Extraction of Polychlorinated Biphenyls: Evaluation of a Column Technique Applied to Polar Bear and Seal Tissue
Authors: Bowes Gerald W , Lewis Jennifer A
Published: February 2020

A column extraction procedure was evaluated for the extraction of polychlorinated biphenyls (PCB) from polar bear and seal liver and fat tissue. DDE (2,2-bis (p-chlorophenyl)-l,l-dichloroethylene) was also present in these tissues, and was quantitated for comparative purposes. Two solvent systems were compared: hexane and chloroform-methanol. The chlorinated hydrocarbons were also separated from the liver and fat by digestion of tissue in hot perchloric-glacial acetic acid, and treatment of tissue with acetone and hot isopropanol (considered to be an exhaustive extraction method for lipid). Six replicate extractions were performed for each of the 4 procedures applied to the 4 tissues. The results suggest that the column technique is excellent for extraction of these chlorinated hydrocarbons from animal tissue. Hexane eluted through a sodium sulfate- tissue mixture in a column was as effective in extracting PCB and DDE from polar bear and seal fat as the standard method of comparison (acetone-isopropanol), and slightly less effective (2—4%) in recovering them from liver. These results also indicate that PCB and DDT compounds are associated with the nonpolar lipid component in the cell. A fraction collection study with polar bear liver and fat shows that hexane removes the compounds rapidly from the 2 tissue types. Most of the PCB and DDE is eluted in the first 50 ml.
Determination of Low Levels of Cadmium in Foods Using a Chelating Ion Exchange Resin
Authors: Baetz Richard A , Kenner Charles T
Published: February 2020

A method is described for the determination of cadmium in foods which utilizes the AOAC HN03, H2S04, H202 digestion procedure catalyzed by V2O5. The cadmium is separated from the neutralized digest by a chelating ion exchange resin, eluted with H2S04, and determined by atomic absorption spectrophotometry. The average recovery of 0.30 ppm cadmium added to 7 commodities was 94% with a standard deviation of 2.8%, which compares favorably with the AOAC dithizone extraction method. The transfer, washing, and elution of 6 samples by the proposed method requires approximately 2 hr. The method allows the determination of as little as 10 ppb cadmium.
Chlorinated Hydrocarbon Pesticide Residues in Foodstuffs: Comparison of Methods
Authors: Smart Nigel A , Hill Alan R C , Roughan Patricia A
Published: February 2020

The AOAC, de Faubert Maunder et al., and Wood methods have been examined for determining BHC, aldrin, heptachlor, DDT, and their major metabolites in milk, butter, cheese, and eggs. Also, the AOAC and the Laboratory of the Government Chemist (UK) methods have been investigated for these pesticides in apples, and both of the latter methods, together with a current EEC method, have been evaluated for measuring the pesticides in potatoes, carrots, and cabbages. Recoveries for these methods were determined by using samples with both added and incurred pesticide residues. There were no gross discrepancies in the results obtained by the different methods, although for certain foodstuffs and in certain situations some methods appeared preferable to others.
Colorimetric Determination of Paraquat Residues in Soil and Water
Authors: Pope John D , Benner Jacquelyn E
Published: February 2020

A modified colorimetric method is presented for the determination of paraquat in agricultural arunoff samples. The soil extraction step of existing methods is shortened, making the method more suitable for routine analysis of large numbers of samples. Recoveries from spiked soil samples (0.5–5.0 ppm) and water samples (0.1–2.0 ppm) averaged 91-98 and 80-94%, respectively.
High-Pressure Liquid Chromatographic Determination of Uncombined Intermediates in FD&C Red No. 40
Authors: Singh Manjeet
Published: February 2020

A high-pressure liquid chromatographic method was developed for the isolation and determination of uncombined intermediates in FD&C Red No. 40 (Allura Red AC, food color). Samples of FD&C Red No. 40 containing 0.1–0.4% cresidine sulfonic acid, 0.1–0.4% Schaeffer's salt, and 0.3–1.0% 6,6'-oxybis(2-naphthalenesulfonic acid) were prepared and analyzed using this method. Recoveries ranged between 92 and 101%. When 32 samples of FD&C Red No. 40 were analyzed by the conventional column chromatographic method as well as by the high-pressure liquid chromatographic method, good agreement was obtained between the 2 methods.
Solubility of Sterigmatocystin
Authors: Steyn Martin
Published: February 2020

The solubility of sterigmatocystin, a carcinogenic and toxic mycotoxin, was determined in 48 solvents. The results indicated that with few exceptions, it is relatively insoluble in most solvents tested. There seemed to be no correlation between the solubility of sterigmatocystin and the dipole moments, dielectric constants, or solubility parameters of the solvents.
Assay of L( + )-Ascorbic Acid in Buttermilk by Densitometric Transmittance Measurement of the Dehydroascorbic Acid Osazone
Authors: Beljaars Paul R , Steenbergen Horrocks Wouter Van , Rondags Theo M M
Published: February 2020

A study is presented for the quantitative analysis of ascorbic acid in buttermilk samples, using densitometric transmittance measurements. The procedure is based on oxidation of ascorbic acid to dehydroascorbic acid, followed by reaction with 2,4-dinitrophenylhydrazine to form the dinitrosazone. The osazone is separated from interfering substances in the sample by thin layer chromatography (TLC) on silica gel G plates developed with chloroform-ethyl acetate-acetic acid (60+35+5) . The TLC plates are scanned with a flying-spot densitometer. The relationship between integrated signal and concentration is linear for 0.08—1.00 fig ascorbic acid (coefficient of variation 3—4%). Deviations from Beer's law start to appear at levels higher than 1.00 fig ascorbic acid. A mean coefficient of variation of 3.5±1.1% (P = 95%) was established for standard spot measurements (3 spots averaged) on 15 chromatoplates. Recovery of ascorbic acid added to buttermik was 98% (coefficient of variation 7.2%). Results of this study are compared with those reported for spectrophotometric, titrimetric, and potentiometric procedures. The proposed method is less accurate because of interferences and the subsequent variables which arise as a result of taking transmittance measurements through an opaque medium.
Possible Interference in the Measurement of Lead and Cadmium from Elements Found in Fish Muscle
Authors: Childs Ernest A , Gaffke John N
Published: February 2020

The effects of various elements found in fish muscle on the measurement of lead and cadmium by atomic absorption spectrophotometry in either an aqueous or an organic solvent system were evaluated. Although a number of elements altered the measurement, the composite effect for both cadmium and lead in either solvent system was <± 10%. The extent of interference of all added elements was found to be a function of the amount of lead or cadmium present.
Perchlorination of Polychlorinated Biphenyls
Authors: Huckins James N , Swanson Jerome E , Stalling David L
Published: February 2020

A simple and efficient method for the perchlorination of polychlorinated biphenyls (PCBs) to decachlorobiphenyl, using antimony pentachloride, is described. Average yields of decachlorobiphenyl from 3 individual samples of Aroclors 1016 and 1254 were 85 and 104%, respectively. Bromine was identified as a contaminant in certain lots of antimony pentachloride. PCB perchlorinations with bromide-contaminated antimony pentachloride resulted in significant amounts of bromononachlorobiphenyl.