bluuebunny/crossref_metadata_2025 huggingface dataset:
Anomalous Results in the Determination of Diethylcarbonate in Wine
Authors: McCalla Mark A , Barr Garold R , Kipp William H
Published: February 2020

Routine analyses of some wines for the presence of diethylcarbonate, using AOAC method 11.066—11.068, show a peak with the same retention time as diethylcarbonate, although an infrared spectrum of the peak conclusively proves that diethylcarbonate is not present. Spectra of components with similar retention times have been examined but the component or components of the peak have not been identified.
Separation and Ultraviolet Absorbance Techniques for Determining Dihydrotachysterol in Pharmaceutical Preparations
Authors: Hom Foo S , Veresh Stephen A , Ebert William R
Published: February 2020

Three separation techniques and ultraviolet (UV) spectrophotometry are described for dihydrotachysterol (DHT). The absorbance procedure eliminates the necessity of establishing a regular baseline, which is advantageous in certain cases. The relative absorbance values obey Beer’s law in the range of 1—10 μg DHT/ml ethanol. An absorbance ratio check ensures the applicability of the method with respect to the degree of allowable interference present. The absorbance ratio values at the indicated wavelengths at this concentration range and in the absence of any interferences are relatviely constant. The UV absorbance could serve as the common final determinative step for the other techniques, either singly or in combination, for quantitating DHT in preparations that require varying degrees of cleanup through extraction, saponification, and thin layer chromatography. The respective mean per cent recoveries and their relative standard deviations for a 50 μg DHT standard sample treated by the 3 techniques are 99.6±:0.5, 98.5±1.1, and 97.3±: 3.3%. Content uniformity determination of DHT in tablets and in soft gelatin capsules is also presented, and precautions are discussed.
Specific Solvation of Ion-Pairs: Examination of Anion-Solvent Complexes by Spectral Methods
Authors: Venable Richard M , Doyle Thomas D
Published: February 2020

The results of experiments performed using infrared (IR) and nuclear magnetic resonance spectroscopy support the theory that chloroform associates by hydrogen bonding to the halide ion of ion-pairs. IR spectra of dextromethorphan hydrobromide in chloroform showed the same effect. This provides a definitive, albeit qualitative, demonstration of the controversial concept of specific solvation of ion-pairs, central to an understanding of solvent effects in analysis of drugs by ion-pair partition. Quantitative implications are less clear. Indications that several molecules of chloroform may be involved in complexation are presented and discussed. Results of similar experiments with methylene chloride are inconclusive.
High Performance Liquid Chromatographic Determination of Sorbic Acid in Wine
Authors: McCalla Mark A , Mark Frances G , Kipp William H
Published: February 2020

A method is described for the qualitative and quantitative determination of 2,4-hexadienoic acid (sorbic acid) by high performance liquid chromatography (HPLC). The results show excellent reproducibility (±2.55%) and agree well with values obtained using the official AOAC ultraviolet method for both fortified wine and commercial wines. Sorbic acid is separated by HPLC, using a strong anion exchange resin, Zipax SAX, eluted with 0.01M Na2B4O7, and detected using UV (254 nm) detector. Sodium benzoate is used as an internal standard.
Aflatoxin: Comparison of Analyses of Corn by Various Methods
Authors: Shotwell Odette L , Goulden Marion L
Published: February 2020

Two methods were evaluated for determining levels of aflatoxin: one developed for peanuts and peanut products (BF method) ; the other (Pons method) for cottonseed products. Both were applied to corn, and results were compared with those obtained with the official first action CB method adopted for corn. Recoveries were much lower with the BF method than with the official AOAC method. Recoveries of aflatoxin B1 with the Pons method were satisfactory in samples containing less than 50 μg aflatoxin B1/kg, but only about 50% for samples spiked at 50 and 100 μg/kg; however, no aflatoxin G was detected in naturally contaminated corn, whereas G aflatoxins were detected with the CB method. Reducing the amounts of solvents used in the official AOAC method was also studied. The extraction solvent, chloroform, could be decreased from 250 ml to 150 ml, and washing and eluting solvents for column chromatography could be reduced by half without affecting results in this study.
Butyl Ester Preparation for Gas-Liquid Chromatographic Determination of Fatty Acids in Butter
Authors: Iverson John L , Sheppard Alan J
Published: February 2020

Butter oil is extracted from butter with hexane, using a rolling boil technique. The resulting 10% butter oil in hexane is converted to butyl esters, using butanol in place of methanol as specified in the official final action method, 28.063–28.067. A water wash and centrifuge technique is used to remove butanol from the n-hexane-butyl ester solution. Conversions to butyl esters are quantitative by the boron trifluoride, sulfuric acid, and sodium butoxide procedures. When methyl ester methods are used, there are serious losses of the short chain volatile and water-soluble acids, making the methyl ester procedures questionable for determining the authenticity of milk fat.
Use of Three Optical Systems to Obtain a Microscopic Profile of Asbestos and Other Nonopaque Particulate Matter Larger than 5 μm in Parenteral Drugs
Authors: Auerbach Leonora
Published: February 2020

A comparative microscopic study of chrysotile fibers was conducted, using 3 sequential optical systems: plane polarized light (PL), phase contrast (PC), and Nomarski differential interference contrast (NDIC) for complementary image analyses. The introduction of NDIC for qualitative and quantitative analyses of particulate matter >5 μm resolves the problem of diffraction halos encountered in PC microscopy. High optical contrast, the instrumental characteristic of NDIC, is particularly useful for the detection of chrysotile fibers at a magnification of 500 ×.
Occurrence and Distribution of 2-Butanol, 1-Butanol, 1-Pentanol, and 1-Hexanol in Distilled Alcoholic Beverages
Authors: Barnett John H , Einsmann Joanne R
Published: February 2020

A survey was made of the distribution of 2-butanol, 1-butanol, 1-pentanol, and 1-hexanol in 198 brands of distilled alcoholic beverages. The principal concern of this study was to determine the applicability of any of the 4 congeners studied to be used as parameters in alcoholic beverage characterization. 1-Pentanol has very narrow use, because it occurred significantly in only 1 brand. 1-Butanol and 2-butanol show intermediate possibilities. 1-Hexanol had wide distributions, and was judged best of the 4 as a parameter. A distinction was shown between 2 brands, similar in other parameters, on the basis of the 1-hexanol content of each. In a 7-year survey, 1-hexanol was consistently characteristic for a single brand. All analyses were done using dual columns, dual flame ionization detectors in a gas-liquid chromatographic system, employing temperature programming from 50 to 150°C. Columns contained 2% Carbowax 20M, 3% Carbowax 1500, and 1% mineral oil on 45—60 mesh Chromosorb G. In addition to the 4 congeners mentioned, the following are also separated by this procedure: acetaldehyde, methyl acetate, ethyl acetate, methanol, 1-propanol, isobutyl alcohol, isoamyl acetate, isoamyl alcohol, hexyl acetate, ethyl caprylate, and 2-furfural.
Comparison of Accuracy, Precision, and Speed of Three Methods for Determining Moisture in Milk Chocolate
Authors: Kreiser Wesley R , Martin Robert A
Published: February 2020

Samples of grated milk chocolate were equilibrated with moisture at increased humidity levels. In the first part of the study, the moisture content of the samples was determined by using the alternative OICC method, manual Karl Fischer titration, and azeotropic distillation. In the second part of the study, the AOAC official method (13.002), azeotropic distillation, and an automated Karl Fischer titration were used for the moisture determination. The results show that the Karl Fischer titration method is more accurate, more precise, and much faster than either of the official methods tested. The azeotropic distillation method gives results that are comparable with those obtained using the Karl Fischer titration method but it requires much more time.
Thin Layer Chromatographic Detection of Amomum subulatum Roxb in Elletaria cardamomum Maton
Authors: Sen Asit R , Sengupta Pratima , Sardar Pranab K , Roy Bidhan R
Published: February 2020

A thin layer chromatographic method has been developed that distinguishes and differentiates true cardamom (Elletaria cardamomum Maton) and greater cardamom (Amomum subulatum Roxb). Extracted volatile oils are chromatographed on silica gel G with n-hexanediethyl ether (80+20) solvent system and visualized with a saturated solution of antimony trichloride in chloroform. The chromatographic pattern permits the detection of adulteration of one by the other at levels as low as 5%.
Assay of Thiamine in Foods, Using Manual and Semiautomated Fluorometric and Microbiological Methods
Authors: Defibaugh Phillip W , Smith Jeffrey S , Weeks Cora E
Published: February 2020

Three methods for the determination of thiamine in foods were evaluated for accuracy, recovery, and precision: a manual fluorescent method, a semiautomated fluorescent method, and a Lactobacillus viridescens microbiological assay. Thiamine in the samples was destroyed with clam tissue thiaminase; a known amount of thiamine hydrochloride was then added to the extract; and the thiamine recovery was determined. For 14 commercially processed food products analyzed by the manual and semiautomated methods, the mean per cent recovery values and standard deviations were 91.2±8.92 and 99.3±3.13%, respectively. Eight of these products were analyzed by all 3 methods. The mean per cent recoveries and standard deviations for these 8 samples were 90.7±8.97, 101±2.52, and 99.9± 1.03%, respectively, for the manual, semiautomated, and microbiological methods. The microbiological method with L. viridescens gave the best results for the products tested. The concentration of vitamin which can be measured is such that samples of low label declaration present no problems. The semiautomated method offers a rapid and accurate method of thiamine assay. The chemical reactions are identical to those of the official method. The major difference between the methods is in the sample cleanup. It is postulated that the low recovery observed for the manual method is due to incomplete elution of thiamine in the column purification step.
Rapid Spectrophotometric Determination of Ascorbic Acid in Citrus Fruits
Authors: Kamangar Teymour , Fawzi Ahmad B , Maghssoudi Rostam H
Published: February 2020

A new spectrophotometric method has been developed for determining ascorbic acid in citrus fruits. The method is based on interaction between dimethoxydiquinone and ascorbic acid, followed by extraction with chloroform. The resulting chloroform solution gives a maximum absorption at 530 nm, a determination limit of 22.0 μg/ml, and a linear range from 22.0 to 97.5 μg/ml. The molar absorptivity of the chloroform solution was 1.62 × 103. The reaction was quantitative over the pH range from 3.0 to 7.0. Ascorbic acid in citrus fruits was successfully determined by this method. Comparison of results with those obtained by using the AOAC method showed excellent agreement; the average recovery for the analysis of orange, grapefruit, and lemon juices was 100±0.3%.
Methodology for Recognition of Invasive Potential of Escherichia coli
Authors: Mehlman Ira J , Eide Elmer L , Sanders Arvey C , Fishbein Morris , Aulisio Calvin C G
Published: February 2020

Surveillance for dysentery-related invasive potential in bacteria using the Sereny keratoconjunctivitis test is restricted by expense, time factor, and necessity for confirmation. Primary screening of isolates in a standardized mammalian cell culture system is recommended. Bacteria are grown 20 hr in veal infusion, washed, and resuspended in 20% heat-inactivated fetal bovine serum (FBS) supplemented with 0.12% brain heart infusion and 0.1% bile salts. The HeLa culture is grown 20 hr as a monolayer in chamber slides with 90% minimal essential medium (MEM)-10% FBS. The host culture is infected at a ratio of 10 bacteria/ mammalian cell for 3 hr at 35°C. The infection medium is replaced with MEM-FBS supplemented with 300 μg lysozyme and 5 μg gentamycin/ml. The infected monolayer is incubated 5 hr at 35°C to permit intracellular multiplication. Specimens arc washed, fixed with methanol, and stained successively with May-Grunwald and Giemsa dyes. Bacteria occur within the cytoplasm if invasion has occurred. The criterion for a positive test is that 1% of the host cells possesses at least 5 bacteria in 2 of 3 trials. Invasiveness is correlated with and possibly pre-conditioned by cytotoxic principle(s). Infectivity rates vary from 0 to 30%. The cytopathic effect is noted in 5–50% of HeLa cells. Positive results must be confirmed by the Sereny test.
Gas-Liquid Chromatographic Headspace Technique for Determination of Vinyl Chloride in Corn Oil and Three Food-Simulating Solvents
Authors: Diachenko Gregory W , Breder Charles V , Brown Margaret E , Dennison J Lawrence
Published: February 2020

A gas-liquid chromatographic headspace technique for the determination of vinyl chloride (VC) in com oil, 50% ethanol, 3% acetic acid, and n-heptane is described. These food-simulating solvents and the corn oil are placed in septum-sealed bottles and heated to 90°C, and aliquots of headspace vapor are injected into a gas-liquid chromatograph equipped with a flame ionization detector. VC may be quantitated at concentrations of 1 ppb or less. This technique was used to measure the migration of VC into corn oil and 50% ethanol from 2 unplasticized polyvinyl chloride sheets containing 0.28 and 0.44 ppm residual monomer.
Sensitive Silica Gel-Packed Flowcell for Fluorometric Detection of Aflatoxins by High Pressure Liquid Chromatography
Authors: Panalaks Thavil , Scott Peter M
Published: February 2020

Aflatoxins B1, B2, G1, and G2 were quantitatively detected by High pressure liquid chromatography on a 5 μm Lichrosorb column, using a Lichrosorb-packed flowcell in the fluorometric detector. The relationship between peak height and the amount injected was linear only up to about 2 ng but showed a linear log-log relationship. Methods for constructing and packing the flowcell are given. A guard column and venting valve were used to minimize deterioration of the analytical column and the adsorbent-packed flowcell. The method was applied to a peanut butter extract, although with the cleanup procedure used, the life expectancy of the flowcell is limited.
Collaborative Study of Modified AOAC Method of Analysis for Nitrite in Meat and Meat Products
Authors: Fiddler Rosemary Nicholas
Published: February 2020

A modified version of the AOAC method of analysis for nitrite in meat and meat products was tested collaboratively by 23 laboratories. Results were compared with those obtained by the official AOAC method. Recommended modifications include: (a) substitution of N-(1-naphthyl) ethylenediamine and sulfanilamide for Griess reagent, (b) separate addition and 1:10 dilution of the above reagents, (c) 20 min color development and absorbance read at 540 nm, (d) substitution of NaNO2 for AgNO2 and NaCl, (e) omission of mercuric chloride, (f) screening of filter paper for nitrite contamination, (g) more precise dilution of sample aliquot, and (h) standard curve linear up to 10 μg N/50 ml. Results were statistically treated by Youden’s technique for comparing 2 methods, using a matched pair sample scheme. The random error for the modified method was significantly lower than the random error for the official method. A t-test showed no difference in bias between the 2 methods.
Collaborative Study of Precision Characteristics of the AOAC Method for Crude Fat in Meat and Meat Products
Authors: Pettinati Julio D , Swift Clifton E
Published: February 2020

A collaborative study of determination of fat by AOAC method 24.005(a) or (b) was conducted to gain more knowledge regarding its characteristics of precision. Twelve analysts in meat and food industry laboratories each performed 4 determinations on 7 samples containing 3.4–48% fat. The following characteristics of precision of the method were established: Variation between duplicate determinations was 0.3% fat; within-laboratory repeatability on separate days was 0.3% fat for samples containing up to 27% fat and 0.7% for samples containing 48% fat; variation among laboratories, including variation due to laboratory-sample interaction, was 0.4% fat; and reproducibility, which includes variations of determinations on a sample by different analysts using different sets of equipment in different laboratories, was 0.6% fat. This information is especially useful for comparative evaluations of alternative methods of fat determination.
Comparison of X-Ray Fluorescence, Atomic Absorption, and Gravimetric Methods for the Determination of Lead in Glassware
Authors: Prager Manfred J , Graves Donald
Published: February 2020

Methods were developed for determining per cent levels of lead in glassware by atomic absorption and x-ray fluorescence spectroscopy. The procedures were evaluated by comparison with a gravimetric method, using previously analyzed commercial glass samples. For atomic absorption spectrometry, samples are dissolved in a mixture of HF and HNO3. Solutions are nebulized into an acetylene-air flame and absorption is measured at 261.4 nm, a secondary line used in order to avoid large dilutions. For x-ray fluorescence analysis, samples are fused, ground, and then pressed into pellets. The intensity of the Pb Lα line corrected for background is measured. Regression analysis of data obtained with 15 commercial glassware samples shows that there is no significant difference among x-ray fluorescence, atomic absorption, and gravimetric results. Statistical tests performed with data on 4 reference materials indicate satisfactory accuracy for both instrumental methods. The atomic absorption analysis is the fastest and simplest of the 3 methods.
Detection and Semiquantitative Estimation of Thyroxine and Diiodothyronine in Liothyronine Sodium
Authors: Cieri Ugo R , Illuminati James C
Published: February 2020

A method is presented for the detection and semiquantitative estimation of thyroxine and diiodothyronine in liothyronine sodium. Thyroxine is detected by thin layer chromatography, using silica gel H plates developed in butanol-acetone-ammonia (30+55+15) and sprayed with a 2,7-dichlorofluorescein solution, and estimated by comparison with standard spots. For quantitative results, a larger amount of sample is applied as a streak on a fluorescent silica gel H plate. After a 5 hr development, the band is scraped off and extracted in a small volume of 0.1N NaOH; the extract is centrifuged, transferred to a 2 cm microcell, and examined spectrophotometrically. The diiodothyronine content of liothyronine sodium is estimated by liquid chromatography on a Bondapak C18 column with 0.01N sodium perchlorate-butanol-acetonitrile (1000+62+188) as the eluting solvent.
Collaborative Study of the Determination of Moisture in Chocolate by Karl Fischer Titration
Authors: Martin Robert A
Published: February 2020

A collaborative study was conducted comparing the AOAC air oven method, 13.002, with the Karl Fischer titration for determining moisture in cacao products. Five samples (4 milk chocolates and 1 confectionery coating) were analyzed by 10 collaborators. The results indicate that the Karl Fischer method gives better precision than the official method. The former method has been adopted as official first action.
Evaluation of Methods for Determining Available P2O5 in Fertilizers
Authors: Johnson Frank J , Farley James A
Published: February 2020

The official AOAC methods for the direct and indirect determination of available P2O5 in fertilizers were compared. The quantity of water-soluble P2O5 removed prior to the citrate extraction has a significant effect on the final available P2O5 result. The quantity of water and the technique used to remove the water-soluble fraction were evaluated. The results indicate that 250 ml and an active wash are necessary to obtain acceptable values for available P2O5. The official method for direct available P2O5 was revised editorially.
Determination of Nitrate Nitrogen in Compound Fertilizers
Authors: Barbera Andrea
Published: February 2020

A commercial electrode is suitable for the determination of nitrate nitrogen in compound fertilizers. The reliability of the electrode was better than 2%. In samples containing from 2.16 to 4.88% nitrate nitrogen, standard deviations ranged from 0.08 to 0.05. The results obtained do not significantly differ from those provided by the Devarda method for nitrate reduction to ammonia and the Kjeldahl method for ammonia determination.
Chromatographic Methods for Analysis of Some Fluorene-9-Carboxylic Acid Derivatives (Morphactins) in Emulsifiable Concentrates and Technical Material
Authors: Cochrane William P , Singh Joginder , Grant Ralph
Published: February 2020

Flurenol-methyl, chloroflurenol-methyl, and dichloroflurenol-methyl in emulsifiable concentrates and technical grade material are separated and identified by thin layer (TLC), high pressure liquid (HPLC), and gas-liquid chromatography (GLC). TLC results were unsatisfactory because of interferences and also variations in the quantitation of the active ingredients. HPLC and GLC gave satisfactory results. Both Porasil C400 and Corasil II HPLC columns gave good resolution of the 3 homologs, with ultraviolet detection at 254 nm. Standard curves had correlation coefficients of 0.990 or better. Analysis by GLC was quantitative with flame ionization detection and a 5% DC-200 column. Response was linear from 200 ng to 2 μg and the coefficient of variation was 2.4%. The mass spectral analysis of the formulated product is also discussed.
Determination of Color in White Wine and White Grape Juice Using the White Wine Colorimeter
Authors: Wildenradt Herb L , Stafford Paul A
Published: February 2020

Further experience with the white wine colorimeter has demonstrated that this instrument provides a simple and reproducible method of color measurement for both finished and unfinished white wines and white grape juices. In view of the proven accuracy and utility of the white wine colorimeter, the method specifying this instrument, 11.B01–11.B02, has been adopted as official final action.
Collaborative Study of the Comparison of Mineral Wool Insulations in the Forensic Laboratory
Authors: Miller Elmer T
Published: February 2020

A method for the comparison of mineral wool insulation specimens was studied collaboratively. Exemplar and questioned specimens are compared microscopically for color of resin, shapes and quantity of slugs or shot, relative fiber diameters, and other gross characteristics. Then the resin is burned off, and the fibers are annealed at 500°C. The heat-treated fibers are compared for shortwave ultraviolet fluorescence, microscopic appearance, solubility in dilute and concentrated hydrochloric acid, and refraction and dispcrsion indices according to 45.002–5.007. Eight collaborators in 6 laboratories compared 8 matched pairs of large samples (such as exemplars) and small samples (such as might be found on a suspect’s clothing).
Preparation and Characterization of Aflatoxin B1-1-(O-carhoxymethyl) Oxime
Authors: Chu Fun S , Hsia M-T Stephen , Sun Piera S
Published: February 2020

A method is described for the preparation and purification of aflatoxin B1-1-(O-carboxymethyl) oxime from aflatoxin The overall yield was about 73–83%. The new aflatoxin B1, derivative was characterized by mass, ultraviolet, infrared, and nuclear magnetic resonance spectral analyses, and was nontoxic to 8-day-old chicken embryos when tested at a concentration of 3.48 μg/egg.
Collaborative Study Comparing the Spiral Plate and Aerobic Plate Count Methods
Authors: Gilchrist James E , Donnelly Cecil B , Peeler James T , Campbell Jeptha E
Published: February 2020

The spiral plate count method is a semiautomated plating technique that greatly reduces manpower and material costs normally associated with the pour plating technique. In this collaborative study, 8 laboratories compared the spiral and pour plating techniques, using 4 samples each of 3 products : frozen pumpkin pie, frozen chicken pot pie, and shampoo. The results show that 10 of the 12 comparisons of means of the pour and spiral methods were not significantly different; 2 values were significant at α = 0.01. Overall, the components of variance were less than that of the current milk standard, and the replicate per cent coefficient of variation was satisfactory. This study indicates that the spiral plate method is an acceptable alternative to the pour plate method; the spiral plate method has been adopted as official first action.
Dry Ash-Voltammetric Determination of Cadmium, Copper, Lead, and Zinc in Foods
Authors: Jones John W , Gajan Raymond J , Boyer Kenneth W , Fiorino John A
Published: February 2020

An analytical method is presented for determining cadmium, copper, and lead by differential pulse anodic stripping voltammetry and zinc by cathodic scan differential pulse voltammetry. Food samples are dry ashed using a sulfuric acid ashing aid, dissolved in dilute nitric acid, buffered at pH ~ 4.3 with an acetate buffer, and quantitatively analyzed using the technique of standard additions at a hanging mercury drop electrode. The quantitation limits (5 times the estimated detection limits) are approximately 5 ng/g for Cd, Cu, and Pb, and 50 ng/g for Zn. Accuracy of the method is established by (a) analysis of NBS Standard Reference Material No. 1577 Bovine Liver, (b) comparison of results obtained by the method described with those obtained by independent analytical methods, and (c) quantitative recovery of analyte metals from fortified, non-canned food samples. Results from an interlaboratory method trial indicate that the method is suitable for the analysis of a variety of food types.
Ruggedness Test for Ashing Methods in Feed: Comparison of Proposed Method of the International Organization for Standardization with AOAC Method
Authors: Torma Laszlo
Published: February 2020

A Youden ruggedness test was performed on the determination of ash in feeds to compare the proposed method of the International Organization for Standardization (ISO) with the official AOAC method. Three samples which contained low, medium, and high ash were analyzed. Six variables were studied : material of the ashing dishes, test portion, preliminary ashing, ashing temperature, ashing time, and additional ashing. Statistical evaluation of the ruggedness test indicated that for Sample A (5.41% average ash), the factors under study did not influence the ash recovery; for Sample B (10.84% average ash), changes in temperature influenced the ash recovery; and for Sample C (13.97% average ash), changes in preliminary ashing, temperature, and additional ashing appeared to influence the ash recovery. It is recommended that the composition of ash be studied further in order to evaluate the temperature and ashing time required to determine nutritionally valuable mineral content.
Collaborative Study of Accuracy and Precision of Rapid Determination of Fat in Meat and Meat Products by Foss-Let Method
Authors: Pettinati Julio D , Swift Clifton E
Published: February 2020

Collaborators in 12 meat and food industry laboratories performed 4 fat determinations each on 7 samples of meat and meat products by the rapid (7–10 min) Foss-Let method and compared the results with those obtained by AOAC method 24.005(a) or 24.005(b). From the overall mean of results on all samples, determinations by the Foss-Let method averaged 0.11% fat higher than by the AOAC method. This difference was not significant by the t-test (P = 0.05), which indicated agreement between the compared methods in determining fat content. Precision of the Foss-Let method was equivalent to and generally slightly better than that of the AOAC method. Standard deviations with the Foss-Let method were 0.2 % fat for between-duplicates and for within-laboratory repeatability; 0.4% fat for between-laboratories, including variation due to laboratory-sample interaction; and 0.5% fat for reproducibility between analysts in different laboratories. The Foss-Let method has been adopted as official first action.
Collaborative Study of Gas-Liquid Chromatographic Method for Analysis of Microencapsulated Methyl Parathion Insecticide
Authors: Karr James J
Published: February 2020

Eleven laboratories collaboratively studied the assay of methyl parathion in 2 formulations of Penncap-M insecticide. The procedure includes a grinding and extraction step, followed by the determination of methyl parathion by flame ionization gas-liquid chromatography. At the 15% level, the variance within laboratories was 0.0905, and among laboratories, 0.0755. At the 20% level, the figures were 0.0556 and 0.0205, respectively. The method has been adopted as official first action.
Gas-Liquid Chromatography of Bromoxynil Octanoate
Authors: Helfant Laurence J
Published: February 2020

A simple, direct method of analysis is proposed that will determine the weight percentage of bromoxynil octanoate in pesticide formulations. Using a gas chromatograph equipped with a flame ionization detector, the ester is separated from its isomers and other reaction by-products, and then quantitated by using an internal standard procedure. This method gives a specific percentage for bromoxynil octanoate, compared with halogen content derived from the Parr bomb procedure that is currently used.
Composition of Ammonium Nitrate-Urea-Water Fertilizer Solutions by Physical Measurements
Authors: Sloan Douglas M , Veales Ronald W
Published: February 2020

A simple method has been developed for determining the composition of fertilizer solutions containing ammonium nitrate, urea, and water. The specific gravity and refractive index are measured under controlled conditions and lines corresponding to these values are plotted on a triangle diagram. Composition is then read at the intercept, with a standard deviation <0.25%, and total nitrogen is computed. The result varies from that obtained by chemical analysis by <±0.25%.
Semiautomated Method for Total Nitrogen in Fertilizers
Authors: Wall Larry L , Gehrke Charles W
Published: February 2020

A semiautomated method (SAM) for total nitrogen in fertilizers has been developed which parallels the official first action semiautomated method for crude protein in feeds, 7.B05–7.B11. The SAM is simple, accurate, precise, flexible, rapid, and requires a minimum of laboratory space. Nitrate was reduced and organic nitrogen materials were digested by the sulfuric-salicylic acid chemistry in the block digestor. The nitrogen, as ammonia, in the digestate was determined automatically at the rate of 40 samples/hr with the automated ammonia analysis system. A small amount of CuSO4, (33 mg/sample) as the SAM digestion catalyst gave total recovery of organic nitrogen in fertilizer. Repeated analyses by the SAM and the AOAC official final action comprehensive nitrogen method (CNM) were made on Magruder fertilizer check samples, liquid and suspension fertilizers, and bulk blended commercial fertilizer materials. Average per cent nitrogen in liquid and suspension samples was higher by the SAM than by the CNM when sample weights similar to those for solid fertilizer were used. The precision of the SAM on liquids also agreed closely with that by the CNM. The only limitation of the semiautomated method was for fertilizer samples containing a Cl/NO3 ratio greater than 0.75 w/w. The SAM recoveries on 3 samples with very high Cl/NO3 ratios wert 94.1–99.1% of those by the CNM. Precision was also less than on any other samples. The average per cent nitrogen found for all experimental samples was 14.68 by the SAM and 14.67 by the CNM. The average relative standard deviation (RSD) for all 22 samples was 1.06% by the SAM and 0.74% by the CNM. When 3 samples with high Cl/NO3 ratios (>0.75) were excluded, the average per cent nitrogen was 15.77 (CNM) and 15.81 (SAM); respective RSDs were 0.68 and 0.65% for the SAM and CNM, respectively. A comparison of results on 405 commercial fertilizer samples by both methods showed an average difference (SAM — CNM) of + 0.017% nitrogen and aver age relative difference of 1.23%.
Gas-Liquid Chromatographic Determination of Trans Unsaturation in Fats and Oils on Packed Columns: Preliminary Studies
Authors: Conacher Henry B S , Iyengar Jagannath R , Beare-Rogers Joyce L
Published: February 2020

Trans isomers in several methyl ester mixtures and in some commercial margarines were separated on a 15′ × ⅛″ stainless steel column containing 10% Silar 10C as stationary phase. With the methyl ester mixtures, good agreement was obtained among known trans contents, trans contents determined by infrared (IR) spectroscopy, and trans contents determined by gas-liquid chromatography (GLC). With commercial margarines, agreement between IR and GLC results was less satisfactory; the latter were approximately 80–85% of the former when trans contents were >20%. When trans contents were <20%, discrepancies were larger. This was considered due to overlap of certain cis and trans positional isomers.
Gas-Liquid Chromatographic Determination of the Plant Growth Regulator Ancymidol in Plant Tissue, Soil, and Water
Authors: West Sheldon D , Day Edgar W
Published: February 2020

A method is presented for the determination of the plant growth regulator ancymidol (α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol) in plant tissue, soil, and water. Residues are converted to an electron-capturing derivative with phosphorus tribromide prior to analysis by gas-liquid chromatography. The method is sensitive to about 0.10 ppm for plant tissue, 0.02—0.05 ppm for soil, and 0.02 ppm for water. Recoveries have averaged greater than 70% for all types of samples.
Assessment of Analytical Method Performance Characteristics : Systematic Error
Authors: Dols Thomas J , Armbrecht Bernard H
Published: February 2020

A random review of the analytical literature shows the need to define more clearly the terms for techniques that are used to assess the merits of analytical methods for a particular purpose. One such performance characteristic is the systematic error or bias of a method. This term is defined and contrasted with other terms commonly used in method assessment. Components of the systematic error are described and techniques are given for their measurement.
Spectrophotometric Determination of Capsaicin
Authors: Ramos Palacio José Jorge
Published: February 2020

A rapid method has been developed for determining the pungency of hot paprika. Paprika is extracted with ethyl acetate, and an ethyl acetate solution of vanadium oxytrichloride is added just before reading at 720 nm. The method is sensitive for small quantities, i.e., less than 0.05%, and it is not necessary to isolate and purify the capsaicin.
High Pressure Liquid Chromatographic Determination of Ethopabate in Feeds
Authors: Schronk Leonard R , Colvin Billy M , Hanks Alan R , Bushway Rodney J
Published: February 2020

A high pressure liquid chromatographic (HPLC) method is described for determining ethopabate in poultry feeds. Feed samples containing ethopabate are finely ground, extracted 30 min by sonification with methanol-water (80+20), and filtered. The extract is cleaned up on an alumina column, and the first 4 ml eluate collected is analyzed. The drug is eluted through a μBondapak C18 column with acetonitrile-water (30+70) at a flow rate of 1.4 ml/min and detected by ultraviolet absorption at 280 nm. Chromatography is complete in 7 min, and detector response is linear. The drug is quantitated by peak height ratios. The procedure described is reproducible and shows good agreement with the official AOAC colorimetric method. The lower limit of detection is 2 ng by HPLC, making the method applicable to residue analyses.
Atomic Absorption Spectrophotometric Determination of Dibutyltin Dilaurate in Finished Feeds: Collaborative Study
Authors: George Glenn M , Frahm Larry J , McDonnell J Patrick
Published: February 2020

Dibutyltin dilaurate is administered in the feed as an active drug for the removal of large roundworms, cecal worms, and several species of tapeworms from chickens and turkeys. The drug is extracted from finished feed with warm CHCl3, the CHCl3 extract is filtered, and a 25 ml aliquot is concentrated in the presence of methanol until all traces of CHCl3 are removed. The methanol solution is diluted and filtered to remove feed interferences, and then 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. Recoveries of 100.5–101.9% tin were obtained for laboratory-prepared feeds. This method was collaboratively studied. The average recovery for dibutyltin dilaurate from 3 feed samples for 8 collaborators was 98.3% with an average coefficient of variation of 5.83%. The method has been adopted as official first action.
High Pressure Liquid Chromatographic Determination of Sulfanitran and Dinsed in Medicated Feeds and Premixes
Authors: Eaves Kathleen L , Colvin Billy M , Hanks Alan R , Bushway Rodney J
Published: February 2020

A simple reverse phase high pressure liquid chromatographic method is described for determining sulfanitran (acetyl-p-nitrophenylsulfanilamide) and Dinsed (dinitrodiphenylsulfonylethylenediamine) in a variety of feed premixes and formulations. Feed premixes are extracted with dimethylformamide, and formulated feeds are extracted with hot methanol. The extract is filtered through medium porosity paper and injected into a liquid chromatograph equipped with a 254 nm ultraviolet detector and a 30 cm column packed with μBondapak C18. The mobile phase is acetonitrile-water (45+55) at a flow rate of 1.0 ml/min. Chromatography was complete in 10 min and peak heights were used for quantitation. Comparison of analyses of commercial samples by this method and by the AOAC colorimetric method, 42.176–42.179, showed close agreement. Recovery of spiked feed samples ranged from 98 to 105%. Butynorate and roxarsone, 2 other drugs which are normally found in combination with sulfanitran and Dinsed, do not interfere.
High Pressure Liquid Chromatographic Determination of Uncombined Intermediates and Subsidiary Colors in Orange B
Authors: Singh Manjeet
Published: February 2020

A high pressure liquid chromatographic (HPLC) method has been developed for isolating and determining uncombined intermediates and subsidiary colors in Orange B. Samples of Orange B containing 0.1–0.3% naphthionic acid, 0.05–0.2 % phenylhydrazine-p-sulfonic acid, 0.2–0.8% pyrazolone-T and ethyl ester of pyrazolone-T, 0.2–1.0% 3-[(4-sulfo-l-naphthalenyl)-azo]-4-amino-l-naphthalenesulfonic acid, and 0.1–6.0% Orange K were prepared and analyzed by using this method. Recoveries ranged from 95 to 103%, except for the phenylhydrazine-p-sulfonic acid which ranged from 95 to 140%. Ten samples of Orange B were analyzed by conventional column and thin layer chromatographic methods as well as by the HPLC method. Good agreement was obtained for naphthionic acid, Orange K, and naphthionic acid plus the naphthionic acid subsidiary.
Analysis of Pesticide Residues by Chemical Derivatization. V. Multiresidue Analysis of Eight Phenoxyalkanoic Acid Herbicides in Natural Waters
Authors: Agemian Haig , Chau Alfred S Y
Published: February 2020

A multiresidue method is presented for the gas-liquid chromatographic determination of phenoxyalkanoic acid herbicides in natural waters. Extraction efficiencies of different organic solvents are considered in developing a solvent extraction scheme for these herbicides from water. Reactions for derivatizing these compounds by using pentafluorobenzyl bromide, boron trichloride-2-chloroethanol, and dicyclohexylcarbodiimide-2-chloroethanol were studied in order to obtain extracts with low blanks to provide the lowest detection limits. Advantages and disadvantages of the 3 methods are discussed. Retention times are twice as long for the pentafluorobenzyl (PFB) esters as for the 2-chloroethyl (2-Cl) esters under the same conditions, although electron capture sensitivity to the former was greater. The PFB esters are easier to form, but the 2-Cl reaction is more specific for these herbicides. Solutions from the boron trichloride reaction gave the cleanest blanks.
Detection of Residual Penicillins in Milk by Using a Bacillus stearothermophilus Disk Assay
Authors: Ouderkirk Larry A
Published: February 2020

A paper disk method based on a procedure described by the International Dairy Federation is presented for the detection of 4 β-lactam antibiotics (penicillin G, ampicillin, cephapirin, and cloxacillin) in whole milk. Bacillus stearothermophilus var. calidolactis, prepared as a stable spore suspension, was used as the test organism. Levels of 0.005 unit penicillin G/ml, 0.005 μg ampicillin or cephapirin/ml, and 0.05 μg cloxacillin/ml were readily detected in whole milk. Results were produced in 3–4 hr. The method offers several advantages, including greater simplicity, sensitivity, and rapidity, over methods now commonly used to detect residual levels of these drugs in milk.
Fluorometric Determination of Histamine in Tuna: Collaborative Study
Authors: Staruszkiewicz Walter F
Published: February 2020

Six samples of canned tuna, albacore, yellow-fin, and skipjack, in water or oil pack were analyzed in duplicate by a fluorometric method and the AOAC colorimetric method. For the fluorometric method, recoveries of histamine added to acceptable tuna averaged 99% with a range of 91 to 107%. Agreement between laboratories for the analyses of decomposed tuna containing 20–200 mg histamine/100 g sample was excellent. Results from the fluorometric method are comparable with those from the AOAC colorimetric method ; the fluorometric method has been adopted as official first action.
Nitration of Benzene as Method for Determining Nitrites and Nitrates in Meat and Meat Products
Authors: Wu Weh S , Saschenbrecker Peter W
Published: February 2020

Nitrites and nitrates in meat and meat products are determined by nitration of benzene in the presence of sulfuric acid. Nitrites are converted to nitrates by permanganate oxidation prior to nitration. The heat of dilution originating from the sulfuric acid is sufficient to complete the reaction. The final product, nitrobenzene, is determined by gas-liquid chromatography and electron capture detection. Peak height quantitation is both accurate and reproducible. Interferences from impurities are rarely encountered, and may be differentiated easily. The method also has potential application to samples other than meat.
High Pressure Liquid Chromatography of Folpet in Formulations: Collaborative Study
Authors: Carlstrom A Aner
Published: February 2020

A simple, rapid method is described for measuring folpet, specifying ultraviolet (UV) detection after high pressure liquid chromatographic separation in a 30 cm by 4 mm column packed with 10 μm diameter silica gel. Formulations are extracted with methylene chloride which contains dibutyl phthalate as an internal standard. After inert materials are precipitated, the supernate is added directly to the column, and the compound is quantitated by peak height ratios. Most pesticides commonly formulated with folpet do not interfere, nor do the related compounds captan and captafol. Retention times and UV response factors relative to folpet are listed for the pesticides most commonly formulated with folpet. Sixteen collaborators made single determinations on 6 samples. The average coefficients of variation were 0.95% for the 2 technical samples, 1.77% for the two 50% wettable powders, and 1.12% for the two 5% dusts. No systematic error was detected. The method has been adopted as official first action.
Determination of Vinylidene Chloride in Saran Films by Electron Capture Gas-Solid Chromatography and Confirmation by Mass Spectrometry
Authors: Birkel Thomas J , Roach John A G , Sphon James A
Published: February 2020

A method is presented for determining vinylidene chloride (VdC) in Saran food packaging films by using electron capture gas-solid chromatography. The VdC present was confirmed by combined gas-solid chromatography-mass spectrometry, employing selected ion recording. The method is capable of detecting ≥5 ppm VdC in films. Production lots of Saran film were analyzed and found to contain 6–30 ppm VdC.
Aflatoxin in Corn: Evaluation of Filter Fluorometer Reading of Minicolumns
Authors: Shotwell Odette L , Goulden Marion L , Kwolek William F
Published: February 2020

A minicolumn method using a filter fluorometer was compared with thin layer chromatography for determining aflatoxin in com. The minicolumn-fluorometer method identified many more samples as aflatoxin-positive than the AOAC CB method. Some corn samples contain a blue-fluorescing substance that interferes with minicolumn chromatography of aflatoxins. Aflatoxin levels measured by the minicolumn-fluorometer method did not correspond to those obtained by the CB method. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.
Differentiating the Saw-Toothed Grain Beetle, Oryzaephilus surinamensis (L.), and the Merchant Grain Beetle, O. mercator (Fauv.), by Morphology of the Male Genitalia
Authors: Olsen Alan R
Published: February 2020

Male saw-toothed grain beetles (Oryzaephilus surinamensis) and merchant grain beetles (O. mercator) were dissected, and the major differences in their genitalia were reviewed. Differences in the morphology of the internal sac, setae of the lateral lobes, chitinous rods of the median lobe, and setae on the eighth sternite are illustrated with photomicrographs. The only other difference between the 2 species is the outline of the adult head. The dissection procedure is described briefly.
High Pressure Liquid Chromatographic Separation and Identification of Vitamins D2 and D3 in the Presence of Fat-Soluble Vitamins in Dosage Forms
Authors: Osadca Modest , Araujo Mercedes
Published: February 2020

A simple and rapid qualitative method is described for determining the presence of vitamin D2 (ergocalciferol) and/or vitamin D3 (cholecalciferol) in various preparations by reverse phase high pressure liquid chromatography (HPLC). When both D2 and D3 are present, this method effectively separates and identifies each vitamin D form by its respective retention time. A significant difference between vitamins D2 and D3 exists in their antirachitic activity in poultry. Preparations can be tested rapidly by this method to ascertain that the correct D vitamin form has been added. Fat-soluble vitamins such as vitamins A, E, K1, and K3 do not interfere. Vitamins D2 and D3 were separated at the baseline in model preparations. As little as 2 ng each of vitamin D2 and vitamin D3 can be separated and identified.
Automated Determination of Protein-Nitrogen in Cereals and Grains
Authors: Revesz Robert N , Aker Norman
Published: February 2020

This paper presents the design, performance, and operational characteristics of a new direct reading instrument for determining nitrogen in cereal and grain. Precision, accuracy, range, speed, ease of operation, sensitivity, sample size, and flexibility of the instrument are presented. Results on various cereals and grains are presented and compared with those obtained by the Kjeldahl technique. The apparatus is the result of research for a rapid method for determining nitrogen in organic material. The instrument uses a combination of a unique high temperature sample oxidation, a sampling valve for separating combustion products, and thermal conductivity detection for the liberated nitrogen in a helium carrier gas.