bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass Spectrometry and Identification of Sterols in Vegetable Oils as Butyryl Esters and Relative Quantitation by Gas Chromatography with Flame Ionization Detection
Authors: Brumley William C , Sheppard Alan J , Rudolf Theodore S , Shen Chih-Shang J , Yasaei Parvin , Sphon James A
Published: February 2020

Electron ionization mass spectrometry (MS) of sterol butyrates is ' described. Fragmentation of common sterol butyrates is related to structure and is discussed in relation to the fragmentation of free sterols I and of commonly used sterol derivatives. Derivatized samples of vegetable oils are introduced using a 10 m capillary gas chromatographic ) (GC) column for complete separation of the sterol butyrates. Quantitation of sterol butyrates in vegetable oils by packed column GC/flame ionization detection is based on percent relative area of peaks identified } by MS. Results of analyses of sunflower, castor, rapeseed, and virgin f olive oils, and other oils are presented. These techniques have been applied to the rapid screening of marketed olive oils for possible adulteration.
Capillary Gas Chromatographic Determination of Some Chlorobiphenyls in Eel Fat: Interlaboratory Study
Authors: Tuinstra Louis G M Th , Roos Arie H , Werdmuller Geziena A
Published: February 2020

A method for determination of 6 individual chlorobiphenyls in eel fat, based on saponification of the sample and determination with capillary gas chromatography, was studied collaboratively. Eleven laboratories submitted analytical results in duplicate for 6 individual chlorobiphenyls on 2 naturally contaminated eel fat samples. The reproducibility coefficient of variation was about 14% at the 1 mg/kg level for each chlorobiphenyl compound and about 23% at the 0.1 mg/kg level. For each compound, the mean recovery was about 90% with a standard deviation varying from 7 to 9%.
Determination of Acrylonitrile in Foods by Headspace-Gas Chromatography with Nitrogen-Sensitive Detection: Collaborative Study
Authors: Page Denis B
Published: February 2020

A headspace-gas chromatographic procedure, with nitrogen-phosphorous (N-P) specific detection for the determination of acrylonitrile (AN) in cold pack cheese, peanut butter, honey butter, and margarine, was collaboratively studied. Seven laboratories analyzed 7 samples of each food for AN at levels ranging from 5 to 60 ppb. For cold pack cheese, mean recoveries for AN added at about 5, 15, and 50 ppb were 65.9, 92.4, and 96.6%, respectively; for peanut butter, mean recoveries for AN added at about 10, 30, and 60 ppb were 59.6, 61.7, and 66.5%, respectively; for honey butter, mean recoveries for AN added at 5,15, and 50 ppb were 88.6, 96.4, and 94.6%, respectively; and for margarine, mean recoveries for AN added at 5, 15, and 50 ppb were 130.6, 91.9, and 88.7%, respectively. The overall coefficients of variation for cold pack cheese, peanut butter, honey butter, and margarine spiked at the above levels were 67.7,22.0, and 38.5%; 71.8,23.8, and 23.8%; 45.3, 30.4, and 13.0%; and 79.7, 38.9, and 16.2%, respectively.
Comparison of Rapid Perfringens Medium and Lactose Sulfite Medium for Detection of Clostridium perfringens
Authors: Smith Marilyn
Published: February 2020

Two tubed media, lactose sulfite (LS) and rapid perfringens medium (RPM), were evaluated and compared for their ability to detect and enumerate Clostridium perfringens in inoculated and naturally contaminated samples. In a 3-tube most probable number system, the number of organisms recovered from spiked samples was several-fold higher with RPM than with LS and was close to the numbers inoculated.Levels detected in 15 naturally contaminated samples were also higher with RPM. Only 13 of the samples were positive for C. perfringens ' with LS medium. These results indicate that RPM is a more effective medium than LS; therefore, its use is recommended
Overview of Physical-Chemical Methods for Determining Aminoglycoside Antibiotics in Tissues and Fluids of Food-Producing Animals
Authors: Shaikh Badar , Allen Edward H
Published: February 2020

A survey of literature is presented dealing with physical-chemical methods for the detection and quantitation of aminoglycoside antibiotics (gentamicin, streptomycin, dihydrostreptomycin, and neomycin) that are used in food-producing animals. Recent developments in cleanup and determinative procedures, particularly liquid chromatography, for these compounds in fluids and tissues are emphasized. Little research has been done on residues in tissues compared with other biological matrices. This review also covers the chemistry, general characteristics, tolerances, and withdrawal times for the approved uses of these antibiotics in animals that are used for food.
Liquid Chromatographic Method for Determination of Furazolidone in Premixes and Complete
Feeds: Collaborative Study
Authors: Smallidge Robert L
Published: February 2020

A liquid chromatographic (LC) method for determining furazolidone in finished feeds and premixes was collaboratively studied. Finished feed sample is extracted with acetone-water (93 + 7) on a Goldfisch apparatus, extracting solvent is removed, and the residual material is dissolved in warm DMF. A solution of tetraethylammonium bromide is added, the fat layer is removed, and the sample is clarified by filtration and injected onto a reverse phase LC system with detection at 365 nm. Premixes, extracted by shaking with DMF and diluted so that the final furazolidone concentration is about 55 (xg/niL, are chromatographed and detected the same as finished feed samples, using a mobile phase of acetonitrile-2% acetic acid (20 + 80). Ten commercial feed samples were preweighed and supplied to 14 collaborators. The 5 matched pairs were chosen to represent the following allowed levels: 0.0055, 0.022, 0.033, 2.2, and 22%. Two familiarization samples at the 0.0055 and 11% levels were also supplied. Instructions called for a single analysis of each sample. Two results were eliminated by the Dixon test. The coefficients of variation, following treatment by the ranking test, ranged from 2.0 at the 22% level to 6.5 at the 0.0055% level. Calculated F-values are not significant (P >0.01) except for the 0.0055% level samples extracted overnight. This method has been adopted official first action
Evaluation of Liquid Chromatographic Methods for Analysis of Chlorphoxim Formulations
Authors: Mount Dwight L , Miles James W
Published: February 2020

Liquid chromatographic (LC) methods for determination of active ingredient in chlorphoxim formulations have been developed independently by Bayer AG and the Centers for Disease Control (CDC). Both methods specify separation on a silica gel column. The Bayer method uses a 5% solution of tetrahydrofuran in hexane as the eluting solvent and quantitates results on the basis of an external standard. The CDC method uses a 5% solution of ethyl acetate in hexane as the eluting solvent and uses 4-fluorophenyl sulfone as an internal standard. The 2 methods were compared by replicate analyses of samples of chlorphoxim technical and water-dispersible powder and emulsifiable concentrate formulations. The precision of both methods was acceptable
TYace Analysis of Chloramphenicol Residues in Eggs, Milk, and Meat: Comparison of Gas Chromatography and Radioimmunoassay
Authors: Arnold Dieter , Somogyi A
Published: February 2020

A radioimmunological assay (RIA) to detect chloramphenicol (CAP) residues in eggs, milk, and meat is described. For tissues and other edible products of chloramphenicol-treated animals (chickens, cows, and pigs), the limit of detection is about 200 βg/kg. Residue levels above 1 ng/kg can easily be quantitated. When highly specific antisera produced in sheep were used, cross-reactivity was insignificant except for metabolites deviating from the parent compound in the acyl side chain only. Thiamphenicol fails to bind to the antisera; hence, it does not interfere with the assay. In the procedure described, the role of cleanup is merely to remove lipids. Thus, skim milk can be analyzed following appropriate dilution without cleanup. The results obtained by RIA were confirmed by gas chromatography with electron capture detection. The new RIA allows rapid, sensitive, and specific screening of large numbers of samples.
Control of Chemical Contaminants in Foods: Past, Present, and Future
Authors: Jelinek Charles F
Published: February 2020

In the late 1930s and early 1940s, almost the only analyses carried out for chemical contaminants in foods were for lead arsenate and other arsenical pesticides in fruits. Since then, a tremendous expansion has occurred in the types of chemical contaminants found in foods and in the activities of the U.S. Food and Drug Administration and other organizations responsible for monitoring and controlling the presence of these contaminants in the food supply. This paper describes the findings and control of additional chemical contaminants in foods, including synthetic pesticides, PCBs (polychlorinated biphenyls), other industrial chemicals, fungal metabolites such as aflatoxins, toxic metals, and radionuclides. The common characteristics of problems connected with these defferent types of contaminants include uncontrolled entry into the food supply, incidents causing extreme public worry, and near impossibility in removing these contaminants from the food supply. Problems may also arise from new technologies and environmental developments. New approaches beyond ordinary regulatory activities are being used to meet these problems. Broader analytical methods requiring less time and faster and more sophisticated toxicological methods are needed to assess the hazard of these environmental food contaminants
Effect of iV-Nitrosothiazolidine-4-Carboxylic Acid on Formation of N-Nitrosothiazolidine in Uncooked Bacon
Authors: Pensabene John W , Fiddler Walter
Published: February 2020

iV-Nitrosothiazolidine-4-carboxylic acid (NTHZC) was recently identified in a variety of smoked fish and cured meat products. While the toxicological properties of NTHZC are currently unknown, it has been speculated that A'-nitrosothiazoIidine (NTHZ) in fried bacon may be caused in part by decarboxylation of NTHZC. A limited survey of uncooked cured meat products failed to demonstrate any correlation between levels of NTHZC and NTHZ. However, NTHZC levels were significantly higher, ranging from 8 to 1400 ppb, than the corresponding NTHZ levels, which ranged from <2 to 18 ppb. Decarboxylation of NTHZC to NTHZ in a model system occurs at 110°C, which is significantly higher than the average bacon processing temperature of 54°C, but lower than the normal frying temperature of 177°C recommended for bacon. Results from both model system and frying experiments with NTHZC and its precursors suggest that NTHZC decarboxylation to NTHZ is not the principal pathway to NTHZ formation in uncooked bacon.
Brine Saturation Technique for Extracting Light Filth from Ground Cinnamon: Intralaboratory Study
Authors: Freeman Clarence C
Published: February 2020

An intralaboratory study was performed using the new brine saturation technique for isolating light filth from ground cinnamon. Recoveries of light filth averaged ^96.5%. The excellent recovery plus improvements in safety and simplicity give this new technique considerable advantage over the present official method.
Headspace Gas Chromatographic Method for Determination of Methyl Bromide in Food Ingredients
Authors: DeVries Jonathan W , Broge James M , Schroeder John P , Bowers Raymond H , Larson Paul A , Burns Nancy M
Published: February 2020

A headspace gas chromatographic (GC) method, which can be automated, has been developed for determination of methyl bromide. This method has been applied to wheat, flour, cocoa, and peanuts. Samples to be analyzed are placed in headspace sample vials, water is added, and the vials are sealed with Teflon-lined septa. After an appropriate equilibration time at 32°C, the samples are analyzed within 10 h. A sample of the headspace is withdrawn and analyzed on a gas chromatograph equipped with an electron capture detector (ECD). Methyl bromide levels were quantitated by comparison of peak area with a standard. The standard was generated by adding a known amount of methyl bromide to a portion of the matrix being analyzed and which was known to be methyl bromide free. The detection limit of the method was 0.4 ppb. The coefficient of variation (CV) was 6.5% for wheat, 8.3% for flour, 3.3% for cocoa, and 11.6% for peanuts.
Rapid Screening Method for Detection of Deoxynivalenol
Authors: Shannon Gail M , Peterson Robert E , Shotwell Odette L
Published: February 2020

A rapid method for detecting deoxynivalenol (DON), also known as vomitoxin, was developed. DON was extracted from grains and other samples with acetonitrile-4% potassium chloride solution (9 + 1). Impurities that would interfere with detection were removed on a Ci8 silica gel reverse phase column. Water was removed from eluates on a hydrophilic matrix column. DON was detected by thin layer chromatography using an aluminum chloride solution to develop the blue response characteristic of the mycotoxin. Total time involved is approximately 30 min. The method was applicable to corn, wheat, and barley at detection levels of 1 ppm, and oats at 1.5 ppm. It is applicable to environmental samples (soil, green plants, and water) at detection levels of 0.75 ppm.
Capillary Gas Chromatographic Determination of Pyrethrins in Low Level Formulations
Authors: Stringham Rodger W , Schulz Ray P
Published: February 2020

Low level pyrethrin formulations are extracted with tetrahydrofuran and determined via capillary gas chromatography with electron capture detection. Quantitation is based on the sum of peak heights of the 6 pyrethrin esters. The method was tested for precision, linearity, and recovery. Quadruplicate analysis of 5 formulations gave an average relative standard deviation of 3.3 %. Linearity and recovery were excellent (correlation coefficient = 0.997, recovery = 101.2%). The data presented support the use of the method for formulations that cannot be analyzed by the AOAC official method.
Liquid Chromatographic Determination of Vanillin and Related Flavor Compounds in Vanilla Extract: Cooperative Study
Authors: Guarino Philip A , Brown Susan M
Published: February 2020

Vanillin and related flavor compounds present in vanilla extract were determined by reverse phase liquid chromatography. Results compared favorably with the official AOAC spectrophotometric method. Compounds such as p-hydroxybenzaldehyde and ethyl vanillin known to interfere in the official method were resolved from vanillin. The method was evaluated by 6 industrial laboratories under the aegis of the Technical Committee of the Flavor and Extract Manufacturers Association. The method is suggested for AOAC collaborative study.
Spectral Characteristics of Florida Orange Juice and Orange Pulp wash. Collaborative Study
Authors: Petrus Donald R , Attaway John A
Published: February 2020

Visible and ultraviolet absorption and room temperature fluorescence excitation and emission spectra, obtained from alcoholic solutions of Florida orange juice (OJ) and orange pulpwash (PW), were used to characterize the collaborative study samples. The absorbance sum at 443, 325, and 280 nm and absorbance 443/325 nm ratio were used to estimate the percent total citrus material (TCM), OJ, PW, and dilution of the samples. Six laboratories participated in the study. Known samples of OJ and PW were given to each laboratory for familiarization and instrumental verification. Ten unknown samples (various combinations of OJ and PW) were analyzed by each laboratory. Three duplicate and 2 "closely matched pair" sample set combinations were reported. The results revealed that the method successfully detected the differences in sample formulations. The UV/vis and fluorescence spectrophotometric method has been adopted official first action for detecting adulteration of Florida orange juice with orange pulpwash.
Titrimetric and Spectrophotometric Determination of Acetylenic Hypnotics, Using Brominating Agents
Authors: Walash Mohamed I , Rizk Mohamed S , El-Brashy Amina
Published: February 2020

Titrimetric and spectrophotometric titration methods are described for the quantitative determination of acetylenic hypnotics ethchlorvynol, ethinamate, and meparfynol carbamate as pure substances and in dosage forms. The methods involve the use of different brominating agents. A known excess of the reagent is added and, after the specified time, the residual reagent is determined iodometrically. These procedures permit semimicro determination (1-20 mg) of the drug. Recoveries ranged from 98.48 ± 0.76 to 102.74 ± 2.60%. The procedures have been successfully applied to pharmaceutical dosage forms; the results agree well with those for compendial methods.
Fluorometric and Spectrophotometric Determination of Pirbuterol Hydrochloride in Authentic and Dosage Forms
Authors: Mohamed Mohamed E , Aboul-Enein Hassan Y
Published: February 2020

Pirbuterol hydrochloride has been assayed in alkaline medium by using a fluorometric method to measure fluorescence intensity at 372 nm with excitation at 310 nm and by the ▵A method at 242 nm.The linearity ranges are 0.5-4 μg/mL and 10-50 μg/mL, respectively. An authentic pirbuterol HC1 sample was analyzed by nonaqueous potentiometric titration using 0.1N perchloric acid, and the results were compared with those for fluorometric and AA methods. The mean percent recoveries for the authentic sample were 98.72 ± 1.13 and 99.24 ± 0.85, respectively. When applied to commercial capsules containing 10 mg and 15 mg each, the fluorometric method gave mean percent recoveries of 101.11 ± 1.05 and 98.12 ± 0.93; the ▵A method gave mean percent recoveries of 100.57 ± 0.83 and 97.80 ± 0.75, respectively.
Technological Aspects of Use of Sulfiting Agents in Food
Authors: Modderman John P
Published: February 2020

A review of the current literature indicates that scientific knowledge of sulfiting agents in food is changing rapidly. Many of the old assumptions about usage of sulfiting agents have been put in doubt by new scientific data. Some basic definitions of sulfiting agents and their chemical behavior in food are presented.
Extraction and Determination of Selected Polycyclic Aromatic Hydrocarbons in Plant Tissues
Authors: Coates John T , Elzerman Alan W , Garrison A Wayne
Published: February 2020

A procedure has been developed for analysis of plant material for polycyclic aromatic hydrocarbons (PAHs). Sonication is used to extract the PAHs from homogenized plant material into acetonitrile and then the PAHs are partitioned into pentane. The pentane extract is fractionated on a micro silicic acid column and is analyzed by capillary gas chromatography with flame ionization detection. Overall method recoveries for 16 PAHs spiked into hybrid grain sorghum ranged from 45 to 90%, with relative standard deviations ranging from 3 to 38% and averaging 17%. This method can be used to measure PAHs in hybrid grain sorghum, fescue grass, and similar plants at the 25 μ/kg level. The procedure was applied to a preliminary study of PAH uptake by sorghum and fescue irrigated with secondary treated municipal wastewater spiked with 5 PAHs. Accumulation of fluoranthene and pyrene by fescue and hybrid grain sorghum from the PAH-contaminated irrigation water was apparent.
Dual Enzyme Method for Determination of Total Nonstructural Carbohydrates
Authors: Khaleeluddin Khaja , Bradford Linda
Published: February 2020

Total nonstructural carbohydrates (TNC) in plant tissue are underestimated by single enzyme (a-amylase or glucoamylase) extraction and overestimated by mild acid hydrolysis. A combination of glucoamylase and mycolase degraded starch completely to glucose at 60°C and pH 4.9. This dual enzyme extraction procedure was effective in determining TNC in plant tissues that do not accumulate fructosans. The reducing sugar (mainly glucose and/or fructose) extracts produced by enzymatic digestion of plant tissue were clarified with barium hydroxide and zinc sulfate solutions and analyzed by the Shaffer-Somogyi copperiodometric titration method. The dual enzyme method hydrolyzed pure starch derived from corn, wheat, and potato, and potato-soluble starch to about 100% glucose, whereas mycolase only yielded about 88% hydrolysis. Although corn starch was completely hydrolyzed in 2 h by the dual enzyme method, plant tissues required at least 24 h hydrolysis for maximum TNC values. Lead acetate precipitation of the protein in the dual enzyme extracts interfered with the copper-iodometric titration. Gelatinization of starch in plant tissue by autoclaving gave higher TNC values than heating on a hot plate for 5 min. The Schaffer-Somogyi copper iodometric titration method could be used to measure/or define the activity of certain enzymes.
Stability-Indicating Method for Determination of Some Acid-Stable Penicillins
Authors: El-Bardicy Mohammed G , Ellaithy Moustafa M , Ibrahim Mohammed W , Ahmad Abdel Kader S
Published: February 2020

A proposed titrimetric procedure for determining some acid-stable penicillins is investigated. The procedure has been used for both pure substances and dosage forms and was fairly accurate. A study of the mechanism of the reaction of the suggested stability-indicating method is presented.
Volatile N-Nitrosamines in Infant Pacifiers Sold in the United States as Determined by Gas Chromatography/Thermal Energy Analysis
Authors: Billedeau Stanley M , Thompson Harold C , Miller Barbara J , Wind Marilyn L
Published: February 2020

Volatile N-nitrosamines in infant latex rubber pacifiers were determined using a modification of a previously described dichloromethane extraction procedure, followed by gas chromatography/thermal energy analysis. Under an interagency agreement between the National Center for Toxicological Research and the Consumer Product Safety Commission (CPSC), data were obtained on the baseline and compliance concentrations of volatile N-nitrosamines in infant pacifiers sold in the United States. Pacifiers made by 18 different manufacturers before and after the January 1, 1984 action level of 60 ppb was set by the CPSC were analyzed for volatile N-nitrosamines. N-Nitrosodibutylamine was the principal N-nitrosamine found, along with trace amounts of N-nitrosodimethylamine, N-nitrosodiethylamine, and N-nitrosopiperidine. Mean total volatile N-nitrosamine levels for baseline and compliance samples were 63.9 and 21.2 ppb, respectively. The pacifier lots sampled after January 1, 1984 showed a significant decrease in contamination levels, indicating that at least 98% of the market share is in compliance with the CPSC enforcement policy for N-nitrosamines in infant pacifiers sold in the United States.
Determination of Copper in Infant Formula by Graphite Furnace Atomic Absorption Spectroscopy with a L’vov Platform
Authors: Hutchinson Donald J , Disinski Francis J , Nardelli Christy A
Published: February 2020

A rapid method for the determination of sub-part-per-million levels of copper in infant formula, which does not require decomposition of the sample matrix before analysis, has been developed. The method uses L’vov platform graphite furnace atomic absorption spectroscopy (GFAAS), a technique that greatly reduces matrix interferences limiting the applicability of normal GFAAS. The sample preparation consists of dilution of a weighed sample of infant formula to a known volume with a 0.5% solution of Triton X-100 in deionized water. The accuracy of the method, as assessed from the results of overspike recovery studies (96.5-101.3% recovery) for different matrix types and comparison to results generated with alternative methodologies, can be considered excellent. The overall precision of the method ranges from 2.5 to 4.3% RSD for different matrix types.
Determination of cis,cis-Methylene Interrupted Polyunsaturated Fatty Acids in Fats and Oils By Capillary Gas Chromatography
Authors: Athnasios Albert K , Healy Edward J , Gross Anthony F , Templeman Gareth J
Published: February 2020

A capillary gas chromatographic (CGC) method is described for the determination of cis,cis-methylene interrupted polyunsaturated fatty acids (cis-PUFA) in fats and oils. The sample is saponified and the liberated fatty acids are esterified to the corresponding methyl esters. The latter are analyzed by CGC using a 60M SP2340 capillary column. Area percent values for 9,12-cis,cis-C18:2 and 9,12,15-cis,cis,cis-C18:3 fatty acid methyl esters are summed to give the total cis-PUFA content. Gas chromatographic results agreed well with those obtained by an enzymatic lipoxygenase method at the 31-48% cis-PUFA levels with a correlation coefficient of 0.98. The method has a precision (relative standard deviation) of 0.33% at a 44.4% cis-PUFA level in margarine oil.
Determination of Fish Core Content in Coated Products: Interlaboratory WEFTA Studies of Three Procedures
Authors: Bon Johannes , Brünner Kerst K , Aitken Angus
Published: February 2020

Four collaborative trials are described in which 3 different methods for the estimation of fish content of coated products were compared to determine their suitability. The methods are a modified version of AOAC method 18.003, an alternative “scraping” method, and a “soaking” method. Seven West European laboratories participated in this collaborative exercise, which was performed on 4 types of coated fish products: raw coated portions of cod (Gadus morhua), partly cooked cod sticks, raw fillets of plaice (Pleuronectes platessa), and partly cooked plaice fillets. The results indicate that precooking strongly affected fish recovery by all 3 methods. Regular portions (of cod) gave higher recoveries than irregular shaped fillets (of plaice). The results do not lead to the conclusion that any method was better than the others.
Uses and Analysis of Sulfites in the Corn Wet Milling Industry
Authors: Coker Lowell E
Published: February 2020

This paper reviews the purpose and principal uses of sulfiting agents in corn wet milling, together with the residual levels of sulfiting agents in finished products. Comparative results of the Monier-Williams method, an iodometric method, and a pararosaniline method for sulfur dioxide are discussed.
Gas Chromatographic Determination of Electron Capture Sensitive Volatile Industrial Chemical Residues in Foods, Using AOAC Pesticide Multiresidue Extraction and Cleanup Procedures
Authors: Yurawecz Martin P , Puma Bartholomew J
Published: February 2020

Electron capture (EC) gas chromatographic (GC) parameters have been developed for determining some of the more volatile industrial chemicals that can be determined by the AOAC multiresidue method for organochlorine and organophosphorus pesticides with modified GC operating conditions. Retention times relative to pentachlorobenzene are reported for 143 industrial chemicals, pesticides, and related compounds on OV-101 GC columns at 130°C. Also reported for most of the compounds are recoveries from fortified samples carried through the AOAC extraction and cleanup procedures for fatty and/or nonfatty foods, Florisil elution characteristics, and GC relative retention times on mixed OV-101 + OV-210 columns at 130°C. Our laboratory has used the modified EC/GC parameters with the AOAC multiresidue extraction/cleanup procedures to determine many volatile halogenated industrial chemical contaminants in foods, chiefly in samples of freshwater fish. Other modifications of the AOAC method are described to improve the tentative identification and quantitative measurement of these volatile residues.
Comparison of Methodology for Determination of Ethylene Dibromide in Grains and Grain-Based Foods
Authors: Clower Marion , McCarthy James P , Carson Louis J
Published: February 2020

Three commonly used methods for determination of ethylene dibromide (EDB) in grains and grain products have been compared. EDB residues were extracted by (1) soaking in hexane, (2) triple co-distillation with hexane from an aqueous sample solution, and (3) soaking in acetone-water (5 + 1). Each method was used for triplicate analyses of 12 samples containing incurred residues of EDB ranging from about 10 to 1000 ppb and representing whole grains (wheat and oats) and intermediate grain-based products such as corn meal and flour. The 4-day hexane soaking method extracted the least EDB. In some cases, this was half of the amount determined by the other methods. Levels from soaking in acetone-water were equal to, or up to 25% greater than, those from distillation. Although soaking for 2 days is required for whole grains in the method, a period of only 16 h was found acceptable for ground products. Results were obtained faster with the distillation method, but more analyst time per sample was required. A single distillation recovered about 80% (40-60% from wheat) of total EDB extracted by triple distillation. Foaming was reduced by the addition of concentrated H2SO4 to the aqueous hexane-sample mixture, plus stirring during distillation, thereby allowing complete recovery of the hexane.
Evaluation of Capillary Gas Chromatography for Pesticide and Industrial Chemical Residue Analysis. II. Comparison of Quantitative Results Obtained on Capillary and Packed Columns
Authors: Fehringer Norbert V , Walters Stephen M
Published: February 2020

Results of pesticide and industrial chemical residue determinations, using both capillary and packed column gas chromatography (GC), in 3 Food and Drug Administration (FDA) laboratories have been compiled and compared. Samples consisted of food products collected for routine residue screening by the respective laboratories. Extracts were prepared by conventional multiresidue methodology. Capillary column systems and operating conditions were selected at the discretion of each laboratory and were therefore variable, although split/splitless injectors in the split mode were used with prescribed precautions in all cases. Packed column systems were operated as specified in the FDA Pesticide Analytical Manual (PAM). Overall correlation between the 2 systems, expressed as the average ratio of packed column result to capillary column result, was 0.99 for 120 determinations in 41 samples. The higher resolving power of the capillary systems allowed quantitation of several residues that were incompletely separated and therefore unquantifiable using the packed columns. Capillary column GC with the split injection technique, used with appropriate precautions, was found to be both reliable and advantageous for regulatory determination of pesticide and industrial chemical residues in foods and feeds.
Evaluation of Collaborative Studies with Special Consideration of the Outlier Problem
Authors: Goetsch P-H , Junge Ch , Kroenert W
Published: February 2020

Practical examples are given of outlier removal considerations when analytical aspects override the decisions of classical statistical tests.
Minimum Criteria for Validation of Analytical Methods
Authors: Williams D R
Published: February 2020

Two aspects must be considered in outlining minimum criteria for validation of analytical methods: management issues and technical issues. Management needs background information and information on issues, options, and implications to identify priorities. The value of the work should be clear to ensure its support and implementation. International adoption of AOAC guidelines for collaborative interlaboratory studies would provide technical criteria for future tests.
Determination of Halogenated Contaminants in Human Adipose Tissue
Authors: Lebel Guy L , Williams David T
Published: February 2020

<A method has been developed for determination of organochlorine contaminants in human adipose tissue. After fat extraction from the tissue with acetone-hexane (15 + 85, v/v), organochlorines were fractionated from fat by gel permeation chromatography with methylene chloride-cyclohexane (1 + 1, v/v) as solvent. After Florisil column cleanup, the GPC extract was analyzed by capillary column gas chromatography using 2 columns of different polarity. Compound identity was confirmed by gas chromatography-mass spectrometry using selected ion monitoring. Recoveries for fortification levels of 10-500 ng/g were greater than 80 % except for trichlorobenzene and hexachlorobutadiene (ca 60%).
Rapid Method for Determination of 2-Hydroxy-4-(Methylthio)butanoic Acid in Poultry Feeds by Capillary Isotachophoresis
Authors: Vinjamoori Dutt V , Schisla Robert M
Published: February 2020

Capillary isotachophoresis, which involves the separation of charged species under an electric field, has been applied to the rapid determination of 2-hydroxy-4-(methylthio)butanoic acid at 0.04-0.50% concentration levels in corn/soy-based poultry feeds, using conductivity detection. The procedure merely involves a 15 min cold water extraction of the sample and a 15 min analysis after injection of the filtrate into the instrument. Since only charged species migrate and non-ionic species stay virtually at the front of the column, extraordinary selectivity can be achieved. The isotachophoresis method is an order of magnitude faster than the gas chromatographic method reported recently and also provides information on HMB-monomer/dimer ratio in the same run. The sample recoveries exceeded 90% in all concentration ranges studied with coefficients of variation less than ± 10%.
Colorimetric Determination of Certain Phenothiazine Drugs by Using Morpholine and Iodine-Potassium Iodide Reagents
Authors: Youssef Adel F , El-Shabouri Salwa R , Mohamed Fardous A , Rageh Abdel Maboud I
Published: February 2020

A colorimetric method was developed for the quantitative estimation of 11 phenothiazine drugs. The method is based on the interaction of unsulfoxidized drug with morpholine and iodine-potassium iodide reagents. The interaction for all studied phenothiazine drugs yields a blue product with 2 absorption maxima: one in the range of 620-640 nm with lower molar absorptivity and the other in the range of 662-690 nm with higher molar absorptivity. The color was stable for at least 10 h. The reproducibility and recovery of the method were excellent. The method was applied successfully to the analysis of various commercially available phenothiazines in different dosage forms. The results were comparable to those obtained by official procedures. The suitability of the method for detection and estimation of promethazine excreted in urine has been suggested by preliminary experiments. Reaction products have been isolated and identified.
Nonaqueous Titration of Halides of Nitrogenous Bases, Using Trifluoromethyl Sulfonic Acid
Authors: Zakhari N Aziz , Kovar K Artur
Published: February 2020

Trifluoromethyl sulfonic acid in glacial acetic acid has been compared with perchloric acid as a titrant in 4 solvent systems: glacial acetic acid, acetic anhydride, a mixture of both, and acetone. The comparison was limited to the determination of halides of nitrogenous bases with and without the use of mercury(II) acetate reagent. The results of the visual titrations showed that both acids are comparable tit rants. However, trifluoromethyl sulfonic acid proved to be superior to perchloric acid in potentiometric titrations carried out in acetic acid-acetic anhydride mixtures. Moreover, the nonoxidizing properties exhibited by trifluoromethyl sulfonic acid proved advantageous over perchloric acid in the visual detection of end points in the titration of phenothiazine derivatives in anhydrous acetic acid, using crystal violet indicator.
Spectrophotometric Determination of L-Pyroglutamic Acid as Indicator of Decomposition or Abuse of Processed Foods
Authors: Ekström Lars-Gösta , Kuivinen Jorma
Published: February 2020

An analytical procedure is described for determination of L-pyroglutamic acid in molasses, wastewater, and catsup. In the cleanup procedure, proteins in the matrix are precipitated with ethanoi and, after acidification, amino acids are retained on a cationic exchanger. The lactam-binding in the pyroglutamic acid ring is quantitatively cleaved by acid hydrolysis to glutamic acid, which is determined spectrophotometrically with an enzymatic method. A commercial test kit is available for performing the latter. Levels of 0.01 mg pyroglutamic acid/mL can be quantitatively determined. This method requires only basic laboratory equipment and is therefore suitable for laboratories with limited resources.
Electron Capture Gas Chromatographic Determination of Traces of Formaldehyde in Milk as the 2,4-Dinitrophenylhydrazone
Authors: Buckley Katherine E , Fisher Lorne J , MacKay Vernon G
Published: February 2020

A quantitative method is described for the determination of formaldehyde in milk by packed-column gas chromatography and electron capture detection. Aldehyde derivatization was carried out in situ with 2,4-dinitrophenyIhydrazine followed by extraction and analysis using an external standard. Average recoveries of 96.3 ± 1.6% were characteristic of the chromatographic method with an estimated detection limit of 0.026 mg/kg. The technique was applied to determination of formaldehyde in milk from cows consuming a formalin-treated feedstuff.
Preparation and Stability of Animal Feed Mixtures Dosed with Rotenone
Authors: Kline David A , Hanna Garry R , Honaker Carl B , Kuhn Gustav O , Jameson C William
Published: February 2020

Studies at Midwest Research Institute for the National Toxicology Program show that rotenone/animal feed mixtures prepared by drymixing are more stable than mixtures produced by dosing the feed with alcoholic solutions of rotenone and then stripping the solvent. Also, recoveries of rotenone from the dry mix feeds are higher than those from feeds dosed by the solution method. A simplified analytical method from one previously reported for rotenone in feed is described.
Colorimetric Determination of Total Iodine in Foods by Iodide-Catalyzed Reduction of Ce+4
Authors: Fischer Peter W F , L’Abbé Mary R , Giroux Alexandre
Published: February 2020

An earlier acid digestion determination of iodine in foods was modified to provide an improved detection limit and to allow for the analysis of a greater variety and larger amounts of foods. The organic material in the sample was oxidized overnight by concentrated nitric acid, followed by digestion in a mixture of concentrated sulfuric and 70% perchloric acid. The iodine was determined by an automated colorimetric method based on the iodide-catalyzed reduction of Ce+4 by As+3. The method had an average relative standard deviation of 3.1% for the samples analyzed, and a detection limit of 0.1 ng/mL in the digested solution and 5 ng/g in a 2 g sample prior to digestion. The recovery of added iodine ranged from 90.3 to 101.3%, using external standards. Samples analyzed included NBS Standard Reference Material 1549, and composites of a variety of dairy products, meat, eggs and fish, cereals, and potatoes. The iodine detected in these samples ranged from 9 ng/g for the potato group to 3360 ng/g for the standard reference material.
Gas Chromatographic Determination of Avilamycin Total Residues in Pig Tissues, Fat, Blood, Feces, and Urine
Authors: Formica Giuseppe , Giannone Carmine
Published: February 2020

A gas chromatographic (GC) procedure is presented for the determination of residues of avilamycin and all its metabolites/conjugates which can be converted to the common moiety dichloroisoeverninic acid (DIA). The method involves alkaline hydrolysis to DIA, cleanup by partitioning with chloroform, acidification of the aqueous phase, and partitioning of DIA into methylene chloride. After methylation of DIA, the product, 3,5-dicMoro-4,6-dimethoxy-2-methylbenzoic acid methyl ester, is cleaned up on a silica gel column prior to the final determination by electron capture GC. The method is sensitive to 0.1 mg/kg avilamycin equivalent. Overall average recoveries were 85.4%, with a standard deviation of 9.1 % for n = 20. Analyses of feces, urine, tissues, and fat of pigs treated with avilamycin demonstrated that 93% of the administered substance is excreted in feces and urine, within 72 h after treatment, and that no residues (<0.1 mg/kg) can be found in the tissues and fat of the animals at any time between 0 and 7 days after treatment with medicated feed.
Residues of Captan and Folpet in Strawberries and Grapes
Authors: Gilvydis Dalia M , Walters Stephen M , Spivak Eugene S , Hedblad Raymond K
Published: February 2020

Fresh strawberries and grapes grown in Michigan and Indiana were surveyed for residues of captan and folpet, 2 fungicides commonly used on these crops. The fungicides were reportedly applied to the crops by overhead irrigation, tractor sprayer, or aerial spraying, in amounts ranging from 0.5 to 6 lb formulation/acre for captan and from 1 to 4 lb formulation/acre for folpet. Reported dates of last application ranged from just 2 days to nearly 5 months before samples were collected. Twenty-eight strawberry samples and 24 grape samples were collected of crops field-treated with one or both of these fungicides. Samples were analyzed by previously described methodology. Captan residues were found in all strawberry samples, ranging from < 0.01 to 1.5 ppm. Folpet was found in only one strawberry sample at 0.041 ppm. Captan residues were found in only 6 grape samples, ranging from < 0.01 to 0.082 ppm. Folpet residues were found in 12 grape samples, ranging from < 0.01 to 0.50 ppm. All residues were well below the current tolerances of 25 ppm for both captan and folpet in strawberries and 50 ppm for captan and 25 ppm for folpet in grapes. Residue levels of these surface-applied, nonsystemic fungicides were inconsistent with amounts and dates of application, most likely because of variations in weather conditions, especially rainfall. Residues were quite stable in frozen sample homogenates, declining only 5-10% after 2 months.
Evaluation of Capillary Gas Chromatography for Multicomponent Drug Analysis
Authors: Thompson Don W
Published: February 2020

Capillary gas chromatography is evaluated for multicomponent drug analysis. A 0.32 mm id × 30 m fused silica column and a 0.75 mm id × 30 m borosilicate glass column (both with OV-1 bonded phase) are investigated. Retention times (relative to caffeine) are presented for 39 drug components representing a variety of chemical classes and pharmacological activities. Reproducibility data are presented for both isothermal and programmed temperature runs on selected drug mixtures. Recovery data are provided for 2 multicomponent drug mixtures prepared to approximate over-the-counter antihistaminic and antitussive preparations.
Colorimetric Determination of C-2 Unsubstituted Phenothiazines, Using Morpholine and N-Bromosuccinimide
Authors: El-Shabouri Salwa R , Youssef Adel F , Mohamed Fardous A , Rageh Abdel Maboud I
Published: February 2020

A colorimetric method for quantitative determination of 6 C-2 unsubstituted phenothiazine derivatives is described. The method is based on reaction of phenothiazine derivative with morpholine and N-bromosuccinimide reagents in aqueous methanol at 60°C to produce a blue color. Beer's law is obeyed in a wide range of concentrations for all 6 compounds at 660 nm. Optimum analytical conditions were determined and the produced color is stable for at least 24 h. Analytical data for determination of the pure compounds are presented together with the application of the proposed method to analysis of some pharmaceutical preparations. The results compare favorably with those of official methods. Furthermore, the method is specific for intact drug in the presence of oxidative decomposition products. The reaction product has been isolated and identified and a possible reaction mechanism is suggested.
Determination of Cadmium, Copper, and Lead in Sodium Chloride Food Salts by Flame Atomic Absorption Spectroscopy
Authors: Alvarez de Eulate M Jesus , Montoro Rosa , Ybañez Nieves , Guardia Miguel De La
Published: February 2020

A method for determination of Cd, Cu, and Pb in sodium chloride food salt samples has been developed. It consists of extraction in 4- methj 1-2-pentanonc of the complexes formed with ammonium pyrrolidine dithiocarbamate and further analysis of the extracts by flame atomic absorption spectroscopy. Detection limits in ng/g salt were 0.2 for Cd, 0.7 for Cu, and 10.0 for Pb. The coefficients of variation of 12 independent analyses were 13% for Cd (at a level of 0.4 ppb), 18% for Cu (1.6 ppb), and 5% for Pb (40 ppb). The recoveries were 100 ± 0% for Cd, 115 ± 14% for Cu, and 100 ± 13% for Pb.
Thin Layer Chromatographic Confirmation of Aflatoxin Mi Extracted from Milk
Authors: Serralheiro Maria Luisa , Quinta Maria De Lourdes
Published: February 2020

Aflatoxin M1 can be confirmed directly on a thin layer plate by reacting the toxin with a mixture of reagents containing p-anisaldehyde. This confirmatory procedure requires only 2 elutions in the same direction using 2 different solvents. The mixture containing p-anisaldehyde is overspotted on Mi after the plate has been developed in toluene-ethyl acetate-ethyl ether-formic acid (25 + 35 + 40 + 5). The plate is heated at 110°C for 10 min and then developed in hexanc-acetonechloroform (15 + 50 + 35). The Rf value of the green fluorescent derivative is less than that of the M1 standard. This confirmatory procedure requires only one-dimensional TLC, so several sample extracts and the standard can be run simultaneously. The minimum detectable quantity of aflatoxin M1 on the TLC plate with this test is 0.3 ng. p- Anisaldehyde reagent solution may also be used as a spray reagent for the confirmation of aflatoxin M1. The procedures described were satisfactory for confirming the mycotoxin in spiked samples of powdered and liquid milk.
Liquid Chromatographic Determination of Zearalenone and Zearalenol in Animal Feeds and Grains, Using Fluorescence Detection
Authors: Bagneris Renee W , Gaul Jean A , Ware George M
Published: February 2020

A liquid chromatographic (LC) method was developed for the determination of zearalenone and zearalenol in grains and mixed animal feeds. Samples are extracted with chloroform and purified by a baseacid liquid-liquid partition. Zearalenone and zearalenol are separated by reverse phase LC and determined by fluorescence detection, excitation wavelength 236 nm with a 418 nm cutoff filter. The method was applied to the determination of zearalenone and zearalenol in 395 survey samples of corn, oats, barley, sorghum, silage, and finished feeds. The limit of detection is 10 ng/g for both toxins. The range of naturally occurring toxins found was 10-4000 ng/g. Average recoveries were 84% for zearalenone and 69% for zearalenol. Coefficients of variation were 24.6% for zearalenone and 30.8% for zearalenol for crop year 1980, and 28.3% for zearalenone and 22.0% for zearalenol for crop year 1981.
Enzyme-Linked Immunosorbent Assay of Aflatoxin Bi in Naturally Contaminated Corn and Cottonseed
Authors: Ram Bhanu P , Hart L Patrick , Shotwell Odette L , Pestka James J
Published: February 2020

Naturally contaminated corn and cottonseed samples were screened for aflatoxin B1 (AFB1) by a direct competitive enzyme-linked immunosorbent assay (ELISA). Samples were blended 5 min in an extraction solvent of methanol-water-dimethylformamide (70 + 29 + 1) and filtered. Filtrates were assayed by direct competition between AFBi in the corn and cottonseed samples and AFB1-peroxidase conjugate for binding to specific antibody adsorbed to a solid phase microtiter plate. Standard curves prepared using the extract of AFB1-free corn and cottonseed samples, and extraction solvent only, showed negligible interference by the sample extract in the performance of ELISA. The AFBi content in corn and dehulled cottonseed samples as determined by ELISA ranged from 7 to 422 μg/kg and 7 to 3258 μg/kg, respectively. When ELISA estimates of AFB1 in corn were compared with values obtained by thin layer chromatography (CB method), the correlation coefficient (n = 10) was 0.95. Average interassay and subsample coefficients of variation for ELISA in corn were 21.4 and 22.0%, respectively. When ELISA estimates of AFB1 in cottonseed were compared with values obtained by liquid chromatography (Pons method), the correlation coefficient (n = 15) was 0.96. Using this ELISA, 36 duplicate sample extracts can be screened for AFB1 in less than 2 h.