bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid Chromatographic Determination of Chloramphenicol in Calf Tissues: Studies of Stability in Muscle, Kidney, and Liver
Authors: Sanders Pascal , Guillot Philippe , Dagorn Michele , Delmas Jean Michel
Published: February 2020

A liquid chromatographic method has been developed for the measurement of chloramphenicol (CAP) in muscle, liver, and kidney. The mean recovery levels were 82.6, 75.3, and 79.2% in muscle, liver, and kidney, respectively. The method was repeatable and reproducible for CAP measurement in muscle, with a detection limit of 1 μg/kg. Investigation of CAP stability in muscle, liver, and kidney showed that CAP stability in muscle was good at -20°C; for spiked liver and kidney, degradation of CAP was observed, and the use of piperonyl butoxlde (PB) for metabolism Inhibition was recommended for recovery and linearity studies. However, PB was unnecessary for preservation of treated animal tissues if samples were cut into cubes and cooled at —20°C, Just after slaughter, pending analysis. With these limitations, CAP can be measured in liver and kidney.
Liquid Chromatographic Method for Multiresidue Determination of Benzimidazoles in Beef Liver and Muscle: Collaborative Study
Authors: Levan Leon W , Barnes Charlie J
Published: February 2020

A liquid chromatographic method for determination of thiabendazole, 5-hydroxythiabendazole, oxfendazole, mebendazole (MBZ), and fenbendazole (FBZ) In cattle liver and muscle was collaboratively studied in 7 laboratories In 1986. For blind fortified samples containing 800 ppb FBZ, average recovery and relative standard deviations for repeatability and reproducibility (RSDr and RSDR) based on results from 6 of the participating laboratories were 83%, 12.7%, and 14.0%, respectively. Recoveries of FBZ from incurred liver samples were more variable. Recoveries of MBZ from livers fortified at the 100 ppb level were encouraging; however, the drug levels were too low in the incurred samples used for MBZ studies. Except for FBZ and MBZ In liver, the study data were not satisfactory. The method has been adopted official first action by AOAC for determination of 800-1600 ppb fenbendazole In liver. The analysis should be repeated using a smaller sample size when Initial analyses show levels greater than 1600 ppb FBZ.
Rapid Immunochemical Screening Method for Afiatoxin B1 in Human and Animal Urine
Authors: Stubblefield R D , Greer J I , Shotwell O L , Aikens A M
Published: February 2020

A method has been developed to determine the presence of afiatoxin B1 in the urine of animals (including humans) by utilizing commercial immunochemical kits that can be used in the field. Urine is treated with diatomaceous earth and filtered to clarify the sample; 2-3 ppb afiatoxin B1, corresponding to about 300 ppb in the ingested feed/food, can be detected in the filtered urine without futher purification. To improve sensitivity, the urine filtrate is passed through a C18 solid phase column to extract the afiatoxin. The column is washed with acetonitrHe-water (15 + 85) and water, afiatoxin B1 is eiuted with methanol-water (7 + 3), and water is added to the eluate, which is then tested for afiatoxin with the test kit. The limit of detection is 0.2 ppb, reflecting consumption of 40 ppb or more afiatoxin In the feed/food. When the initial sample volume is adequate, purification through the C18 column step Is usually sufficient. For limited sample volumes, the eluate from the C18 column is mixed with water, added to an immunosorbent affinity column, and washed with water to remove excess sample matrix and impurities. Afiatoxin B1 is eiuted with acetonltrile. The extract is evaporated under nitrogen and the residue is redissolved in methanolwater (25 + 75). At this purification stage, the limit of detection is reduced to 0.05 ppb.
Multiresidue Screening Method for Fresh Fruits and Vegetables with Gas Chromatographic/Mass Spectrometric Detection
Authors: Liao Wenta , Joe Ton , Cusick William G
Published: February 2020

A gas chromatographic/mass spectrometric (GC/MS) screening method has been developed for the determination of pesticide residues in a variety of crop samples. Samples are extracted with acetonitrlle and partitioned with sodium chloride saturated aqueous solution. Targeted pesticide analytes are separated on a short, narrow bore capillary column, identified by electron ionization MS scanned from 100 to 400 amu, and quantitated by the monitoring of base ions and internal standards. The accuracy of the quantitative determination measured in terms of average percentage recovery of 143 compounds in 13 crop samples was 92% with a relative standard deviation of 22%.
Determination of Oxolinic Acid Residues in Salmon Muscle Tissue by Liquid Chromatography with Fluorescence Detection
Authors: Larocque Lyse , Schnurr Mary , Sved Stephen , Weninger Andrea
Published: February 2020

The present paper describes a method for determination of oxolinic acid in salmon muscle tissue. Tissue (0.5-2 g) mixed with 2 g anhydrous sodium sulfate is extracted twice with ethyl acetate, centrlfuged, and the extract evaporated. The residue is partitioned in a mixture of hexane and 0.01M oxalic acid and the aqueous phase chromatographed using fluorescence detection at 327 nm excitation and 369 nm emission. Calibration and standard curves are linear from 10-200 ppb and 100-2000 ppb at different sensitivity settings. Recoveries ranged from 71-83% in spiked blanks, with a CV of 4-10.3% over a 2-week period. Preliminary results in treated salmon were variable, possibly because some fish refused to eat medicated feed.
Lipid Globule Staining to Aid in Differentiating Bacillus Species
Authors: Harmon Stanley M , Kautter Donald A , Lancette Gayle
Published: February 2020

The use of the lipid globule stain to aid in differentiating the Bacillus cereus group (i.e., B. cereus, B. cereus var. mycoldes, and B. thurlnglensls) from other Bacillus species was investigated. Smears from colonies grown on suitable agar were made on precleaned slides, stained, and examined microscopically for characteristic deep blue lipid globules. The study included a total of 649 cultures of Bacillus species plus 143 Incompletely characterized Bacillus isolates from food. Only B. cereus, B. cereus var. mycoldes, B. thurlnglensls, B. megaterlum, and B. sphaerlcus were consistently positive for lipid globules, although at times, a few cells of B. aneurlnolyilcus and B. thlamlnolytlcus were also positive. The lipid globule stain procedure Is of value In differentiating Bacillus species, especially when performed by an experienced analyst and used in conjunction with tests for cell and spore morphology.
Clostridium perfringens
Authors: Labbé Ronald G
Published: February 2020

In the United States and Canada, Clostridium perfringens remains a leading cause of bacterial food poisoning in humans. It has been primarily associated with meat and poultry products prepared in food service establishments. Fecal spore levels of 104 or more per g are considered indicative of a food poisoning outbreak. However, elevated spore levels of this organism are frequently seen in healthy elderly individuals, an observation that complicates investigations of suspected outbreaks. Recent studies with this population indicate that fecal enterotoxin levels are a valuable and effective assay for confirming outbreaks due to this organism. With regard to the toxin itself, a membrane protein of 50 000-70 000 molecular weight has been isolated as a possible enterotoxin-receptor site. It is the subsequent action of the toxin on membrane structure that results in the loss of ions and fluid associated with illness. In addition, the enterotoxin gene has been cloned in E. coil and sequenced. Using toxin-specific DNA probes, only 6% of non-symptomatic farm animals were found to possess the enterotoxin gene, disproving the hypothesis that all strains of this organism can produce the toxin.
Efficiency of Two Commercial ELISA Kits Compared with the BAM Culture Method for Detecting Listeria in Naturally Contaminated Foods
Authors: Noah Charles W , Ramos Nora C , Gipson Virginia M
Published: February 2020

The efficiency of 2 commercial enzyme-linked Immunosorbent assay (ELISA) kite (Listeria-Tek™ and Tecra™) for detecting Listeria in naturally contaminated foods was evaluated and compared with that of the culture method described in the Bacteriological Analytical Manual (BAM). Both ELISAs use modified University of Vermont (UVM-1) medium as a primary enrichment; the BAM method uses Listeria enrichment broth. Secondary enrichments for Llsterla-Tek and Tecra, respectively, were Fraser broth and UVM-2, which contains additional acriflavln-HCI. When ELISA test results differed, secondary enrichments were tested against the other ELISA; Fraser broth was used to determine recovery rates because of Its superiority over UVM-2. Of the 178 food samples examined, the presence of Listeria was detected and culturally confirmed in 38, 37, and 40 samples by the BAM, Llsterla- Tek, and Tecra methods, respectively. Differences in results of the EUSAs compared with those of the BAM method were not statistically significant; however, differences between results of the 2 ELISA methods were significant. It was concluded that as rapid screening methods, the Llsteria-Tek and the Tecra kits qualify as alternative methods to the BAM cultural method.
Recovery of Salmonella from Shell Eggs
Authors: Stephenson Patricia , Satchell Felicia B , Allen Geraldine , Andrews Wallace H
Published: February 2020

A preenrlchment procedure and a direct selective enrichment procedure were compared for recovery of Salmonella artificially inoculated into liquid whole egg, egg yolk, and egg albumen. For liquid whole egg and egg yolk, the 2 procedures were comparable. With egg albumen, however, preenrlchment In lactose broth gave significantly higher recoveries than did direct selective enrichment in either selenite cystine or tetrathionate broths. The lactose preenrlchment procedure was used to determine the survival of S. enterltldla in egg yolk and egg albumen over a period of 7 days. As shown by most probable number determinations, counts of S. enterltldla Inoculated Into egg albumen decreased by 3 log units, whereas those in egg yolk did not change significantly. It is recommended, therefore, that only the egg yolk be examined for this pathogen. In a comparison of 5 different preenrlchment media (lactose broth, brain heart Infusion broth, trypticase soy broth, buffered peptone water, and nutrient broth), lactose broth was somewhat less productive than the other 4 media for the recovery of Salmonella from egg yolks. Trypticase soy broth gave the highest recovery.
Liquid Chromatographic Determination of Paralytic Shellfish Poisons in Shellfish After Prechromatographic Oxidation
Authors: Lawrence James F , Ménard Cathie
Published: February 2020

A liquid chromatographic method for quantitating paralytic shellfish poison toxins in shellfish has been developed in which the toxins are converted to fluorescent purines by prechromatographic oxidation under mildly basic conditions with hydrogen peroxide or periodate. The addition of ammonium formate to the periodate oxidation reaction greatly improved the yield of fluorescent derivatives for neosaxitoxin, gonyautoxin-1, B-2, and C-3 compared to the same reaction without ammonium formate. As little as 3-6 ng of each of the nonhydroxylated toxins and 7-12 ng of the hydroxylated compounds per gram of shellfish could be detected. Reversed-phase chromatography using ammonium formate in the mobile phase improved the chromatography of neosaxitoxin and B-2 compared to results obtained earlier. Because the oxidation products of neosaxitoxin and B-2 could not be separated, parent compounds were separated before oxidation by using an SPE-COOH ion exchange cartridge. The repeatability coefficient of variation for the oxidation reactions ranged from 3 to 8% for the peroxide reaction, and from 4 to 11 % for the periodate reaction, depending upon the individual toxin determined and its concentration in the extract (0.04-0.55 μg/g). The method was compared to the mouse bioassay and the postcolumn oxidation method. In most cases, results were comparable.
Simple Colorimetric Determination of Carrageenan in Jellies and Salad Dressings
Authors: Yabe Yoshie , Ninomiya Takahiro , Tatsuno Takashi , Okada Taro
Published: February 2020

A simple, rapid colorimetric method is described for the determination of carrageenan (CAR) in foods such as jellies and salad dressings. Alcian blue reagent is added to the sample solution prepared from these foods, then CAR is precipitated selectively as a CAR-alcian blue complex. The precipitate is dissolved in monoethanolamine and determined colorimetrically at 615 nm. Overall recovery for jelly was 93.3% with a coefficient of variation (CV) of 5.8%. Overall recovery for salad dressing was 91.9% with a CV of 3.0%. The detection limit was 0.05%. The results obtained by the proposed method were similar to those obtained by a capillary gas chromatography method.
Bacillus stearothermophilus Disk Assay for Determining Ampicillin Residues in Fish Muscle
Authors: Plakas Steven M , DePaola Angelo , Mox Michael B
Published: February 2020

The Bacillus stearothermophilus disk assay for penicillin in milk (AOAC official method) was adapted for the determination of ampicillin in fish muscle. The method was evaluated in 2 species of cultured fish: channel catfish and striped bass. Recoveries of ampicillin ranged from 99 to 104% when muscle specimens from both species were spiked at concentrations of 0.025-1.00 μg/g. The lower limit of determination (LOD) was 0.025 μg/g. The assay was applied to monitor the elimination of ampicillin from the muscle of striped bass after intravascular administration (dosage of 10 mg/kg body weight). The mean concentrations in the muscle declined from 1.160 μg/g at 2 h to 0.063 μg/g at 18 h. The half-life of ampicillin in the muscle was 3.6 h. Ampicillin concentrations were below LOD at 24 h. No inhibitory activity was observed in the muscle of control fish.
Sensitive and Rapid Reversed-Phase Liquid Chromatography–Fluorescence Method for Determining Bisphenol A Diglycidyl Ether in Aqueous–Based Food Simulants
Authors: Losada P Paseiro , Mahia P López , Odériz L Vázquez , Lozano J Simal , Gándara J Simal
Published: February 2020

A method has been developed for determination of bisphenol A diglycidyl ether (BADGE) in 3 aqueous-based food simulants: water, 15% (v/v) ethanol, and 3% (w/v) acetic acid. BADGE is extracted with C18 cartridges and the extract Is concentrated under a stream of nitrogen. BADGE is quantltated by reversed-phase liquid chromatography with fluorescence detection. Relative precision at 200 μg/L was 3.4%, the detection limit of the method was 0.1 μg/L, and recoveries of spiking concentrations from 1 to 8 μg/L were nearly 100%. Relative standard deviations for the method ranged from 3.5 to 5.9%, depending on the identity of the spiked aqueousbased food simulant.
Analysis of Organochlorine Pesticide Residues Using Simultaneous Injection of Two Capillary Columns with Electron Capture and Electrolytic Conductivity Detectors
Authors: Hopper Marvin L
Published: February 2020

A system has been developed that will allow low level screening of 31 organochlorine pesticide residues using simultaneous injection on 2 dissimilar capillary columns. An electron capture detector was attached to a DB-1701 column, and an electrolytic conductivity detector in the halogen mode was attached to a DB-5 column. Chlorinated pesticide amounts ranging from 0.05 ng for γ-BHC to 1.5 ng for decamethrin can easily be quantitated and confirmed. The system can be used in either the column programmed mode or the isothermal column mode. Good reproducibility was obtained for injections in both modes. This system can easily be retrofitted to any gas chromatograph using on column or split/splitless injectors.
GC/MIP/AED Method for Pesticide Residue Determination in Fruits and Vegetables
Authors: Ting Keh-Chuh , Kho Peng
Published: February 2020

This research describes the results of a gas chromatography/microwave induced plasma/atomic emission detection (GC/MIP/AED) method performed on a Hewlett-Packard 5921A system for pesticide residue analysis in fruits and vegetables. Atotal of 6 experiments were conducted: (1) sensitivity and linearity studies for elements S, P, CI, and N by analyzing dursban; (2) a study of instrument response to CI concentration in pesticide molecules; (3) organochlorinated pesticide recoveries; (4) organophosphate pesticide recoveries; (5) carbamate pesticide recoveries; and (6) investigation of metallic pesticides with pllctran and vendex as standards. The rank according to sensitivity and linearity was found to be as follows: S-181>P-178>CI-479>N-174. Instrument response to the concentration of chlorine atoms in the pesticide molecule was linear, with a correlation coefficient of 0.89. Recoveries of organochlorinated pesticides were 91.7-109.3%, with the exception of citrus, whose recovery was affected by coeluting Interferences. Organophosphate recoveries were 73.2% or higher, except for the cygon oxygen analog, which degraded in the GC system under all circumstances. Carbamate recoveries were inconsistent quantitatively; however, the information generated from elements N and S were useful for qualitative confirmation of other methods, such as LC postcolumn derivatization analysis. Overall, the GC/MIP/AED method is powerful for qualitative confirmation in pesticide residue analysis. The instrument’s capability of acquiring multi-elements (CI and P) selectively and accurately is an alternative method for organochlorinated and organophosphate pesticide residue analyses. In addition, the GC/MIP/AED system is easy to use, simple to maintain, and its chromatograms can be interpreted by any chromatography analyst without much prior training.
CI-906 and CI-925 Cyclization in Rodent Chow Using Liquid Chromatography for Detection and Assay
Authors: Spurlock Carola H
Published: February 2020

Two ACE inhibitors, CI-906 and CI-925, cyclize rap- Idly to the corresponding dlketopiperazlnes PD109 488 and PD 114 009, respectively, in admixture with 5002 rodent chow. After 2 weeks storage at ambient temperature, 90% of the admixed CI-925 and 68% of the admixed CI-906 cyclized. Liquid chromatography (LC) was used to quantitate both parent drugs and cyclized products. Absence of fat and fish meal from the chow affects the reaction. With CI-925 as the test compound, 90% cyclized after only 3 days In fat-free chow, and 80% cyclized after 3 days In chow free of both fat and fish meal. Chow pre-extracted with methanol has less effect than does whole chow. After 2 weeks, 87% CI-925 remained. Cyclization of CI-925 in methanol solution Is also enhanced by the presence of chow extractables. After 2 weeks, 21-25% PD 114 009 was produced in fat-free diet extract, fat- and fish meal-free diet extract, and whole 5002 diet extract, compared to 4-5% produced in methanol alone. We concluded that 5002 chow contains one or more extractable components that promote cyclization of CI-906 and CI-925.
Soxtec Fat Analyzer for Determination of Total Fat in Meat:
Collaborative Study
Authors: Foster Max L , Gonzales Sharon E
Published: February 2020

A new method for determination of total fat in meat and meat products, which uses a commercially available extraction system, was collaboratively studied by 11 laboratories. The study compared the new Soxtec solvent extraction with the Soxhlet method. The new method reduces extraction time, enables recovery of 60-70% of the solvent, and improves safety through external heating. Each laboratory received 6 samples: canned ham, ground beef, frankfurters, fresh pork sausage, hard salami, and beef patties with added soy. Laboratories were Instructed to analyze each sample In duplicate on each of 2 days by both the Soxhlet and Soxtec methods. In general, results for the Soxtec system showed Improved performance. For all samples used in Soxtec analysis, ranges of values for repeatability and reproducibility were Sr, 0.106-0.764; RSDr, 1.01-2.44%; SR, 0.112- 0.799; and RSDR, 1.53-2.84%. The method was adopted first action by AOAC International.
Comparison of Monoclonal Antibody-Based Enzyme-Linked Immunosorbent Assay with Thin-Layer Chromatography and Liquid Chromatography for Aflatoxin B1 Determination in Naturally Contaminated Corn and Mixed Feed
Authors: Hongyo Ken-Ichi , Itoh Yukikatu , Hifumi Emi , Takeyasu Akira , Uda Taizo
Published: February 2020

A 1-step enzyme-linked Immunosorbent assay (EUSA) method, using a highly sensitive and specific monoclonal antibody to aflatoxin B1 (AFB1), was evaluated by comparison with other methods, Including liquid chromatography (LC) and thinlayer chromatography. The detection limit of the ELISA was as low as 100 pg/assay. AFB1 contents of naturally contaminated corn samples were determined by the 3 methods. The relationships among the methods were Investigated, and good correlations were observed. Mixed feeds were also subjected to AFB1 determination by the 3 methods. For our ELISA system, 3 types of sample preparations were tested. For analysis of mixed feed by ELISA, samples must first be purified by column chromatography. When the relationship between LC and ELISA was also investigated, results were found to have a good correlation coefficient.
Liquid Chromatographic Determination
of Fumonisins B1, B2, and B3 in Foods and Feeds
Authors: Sydenham, Eric W , Shephard, Gordon S , Thiel Peter G
Published: February 2020

Three recently described and toxlcologlcally Important Fusarlum mycotoxins, fumonisln B1 (FB1), fumonisln B2 (FB2), and fumonisln B3 (FB3), are the major fumonisins produced In cultures of F. monlllforme, a fungus that occurs worldwide on corn. Contamination of food and feed with F. monlllforme has been associated with a number of diseases In both animals and humans. Aspects of a recently reported liquid chromatographic method for the determination of FB1 and FB2 in corn, including Initial extraction, extract purification, and stability of derivatives, were Investigated and, where necessary, optimized further both to reduce the analysis time and to include the co-determlnatlon of FB3. The method was applied for the determination of FB3, in a series of U.S. feed samples associated with outbreaks of equine leukoencephalomalacla, which were shown previously to contain both FBi and FB2. Twelve of the 13 feed samples contained FB3 at levels ranging between 50 and 2650 ng/g, corresponding to 2.2-18% of the total fumonisln concentrations present in the FB3-posltlve feed samples. This is the first report of the natural occurrence of FB3.
Matrix Solid-Phase Dispersion Isolation and Liquid Chromatographic Determination of Oxolinic Acid in Channel Catfish (Ictalurus punctatus) Muscle Tissue
Authors: Jarboe Herman H , Kleinow Kevin M
Published: February 2020

Matrix solid-phase dispersion Isolation and liquid chromatographic techniques were developed to quantify oxolinic acid (OA) and OA-related metabolites in channel catfish (Ictalurus punctatus) muscle tissue and bile. Mean percent recovery, correlation coefficient, and inter- and intra-assay variabilities were 82.8 ±15.0%, 0.996 ±0.004,12.5 ±8.9%, and 1.22%, respectively, for OA Isolated from fortified muscle tissue. Using the methodologies described in the current study, incurred OA In muscle tissue and 4 OA-related metabolites were Isolated In the bile of dosed catfish.
Solid-Phase Extraction Method for Volatile N-Nitrosamines in Hams Processed with Elastic Rubber Netting
Authors: Pensabene John W , Fiddler Walter , Gates Robert A
Published: February 2020

A method was developed for the determination of volatile N-nitrosamines in hams processed In elastic rubber nettings. The method was based on a modification of a solid-phase extraction (SPE) procedure used in the past to determine selected nitrosamines in different types of cured meat products. The nitrosamines detected in ham most likely originate from the amine precursors in rubber and from the nitrite commonly used in the meat curing process. The method was compared with 2 established procedures for N-nitrosodibutylamine (NDBA) analysis in cured meat products: the mineral oil distillation procedure (MOD) and the low temperature vacuum distillation procedure (LTVD). All 3 methods used the same gas chromatographic/chemlluminescent detection conditions and system. No significant difference was found between the MOD and LTVD methods. These methods were found to yield significantly higher NDBA levels than the SPE procedure. When 2,6-dimethylmorpholine was added to the sample before analysis in the MOD and LTVD procedures, artifactual nitrosamines were formed. No artifactual formation was noted in the SPE method. We propose that the new SPE method replace the current methods being used for analysis of netted, cured meat products.
Liquid Chromatographic Determination of Thiamine, Riboflavin, and Pyridoxine in Infant Formula
Authors: Chase George W , Landen William O , Eitenmiller Ronald R , Soliman Abdel-Gawad M
Published: February 2020

An Ion pairing reversed-phase liquid chromatographic method developed for multivitamin supplements and premlxes was applied to the simultaneous determination of thiamine, riboflavin, and pyridoxine In perchloric acid extracts of milkand soy-based Infant formulas. The method uses m-hydroxy benzoic acid as Internal standard and a mobile phase consisting of water, acetonltrile, hexanesulfonlc acid sodium salt, and ammonium hydroxide solution, adjusted to pH 3.6 with phosphoric acid. The column Is a 15 cm x 3.9 mm id Nova Pak C18. Limits of detection were 0.15 μg/mL for thiamine and 0.09 μg/mL for riboflavin by UV detection at 254 nm, and 0.010 μg/mL for pyridoxine by fluorescence detection. Mean percent recoveries based on triplicate determinations were 102 ± 1.8,102 ± 3.3, and 101 ± 3.1 for thiamine, riboflavin, and pyridoxine, respectively. The results compared favorably with the AOAC methods for thiamine, riboflavin, and pyridoxine.
An FDA Laboratory Approach to Uncovering Potential Fraud in the Generic Drug Industry
Authors: Kirchhoefer Ross D
Published: February 2020

The Division of Drug Analysis of the U.S. Food and Drug Administration In St. Louis, MO, has screened more than 1400 drug samples for potential generic drug fraud by a combination of physical, instrumental, and chemical techniques. The approach to fraud centered around the analysis of exciplents as opposed to the normal approach of analysis of active Ingredients. Approximately 80% of the drug formulation pairs (Innovator and generic) submitted for bloequlvalence testing could be differentiated by a combination of physical and instrumental analysis, mainly thermogravimetrlc analysis (TGA) and Fourier-transform Infrared (FTIR) spectrometry. TGA proved to be the single most useful instrumental technique to determine differences In formulations. Liquid chromatography, gas chromatography, chemical tests, and polarizing microscopy were found to be the most useful tools to differentiate formulations that could not be resolved by FTIR, TGA, or physical comparisons. Xray powder diffraction and nuclear magnetic resonance spectroscopy were found not to be useful techniques to differentiate formulations. No clear-cut evidence of direct fraud was found, but Inconsistencies and suspicious samples were noted. Follow-up inspections based on the laboratory findings will probably occur. The procedures discussed In this article could be streamlined and made more efficient for examining large numbers of potential problem formulations.
C18 Extraction of Atrazine from Small Water Sample Volumes
Authors: Shepherd Timothy R , Carr James D , Duncan Diana , Pederson Darryll T
Published: February 2020

A method was developed to detect atrazine at a 0.05 ppb detection limit with a 10 ml_ sample volume. The herbicide Is extracted from 10 mL water with C18 solid-phase extraction and eluted into a reduction vessel with ethyl acetate. The sample is then evaporated to dryness under a stream of nitrogen and redlssolved for Injection Into a gas chromatograph/ mass spectrometer. Terbuthylazlne is used as Internal standard to compensate for extraction process variables. Standard curves have consistently shown correlation coefficients of 0.99 or better. Duplicate samples show a variance of 5% or less. Twelve samples can be extracted In about 1.5 h with <10 mL organic solvent and minimum glassware.
Determination of Leucogentian Violet in Chicken Fat by Liquid Chromatography with UV Detection
Authors: Heller David N
Published: February 2020

UV detection is proposed as an alternative to electrochemical detection for the determination of leucogentian violet (LGV) in chicken fat by liquid chromatography. UV detection was combined with a previously reported extraction technique and new chromatographic conditions to yield a method that was evaluated at the target level of 10 ppb. Baseline separation of LGV from matrix interferences was achieved with a Cia bonded silica column and a mobile phase of methanol-pH 4 ammonium acetate (90 +10). Average recovery for samples fortified at 5,10, and 20 ppb was 76.4%, with a coefficient of variation (CV) of 4.8%. Fat from chickens raised on feed medicated with 30 ppm gentian violet was found to contain 17.6 ppb LGV, with a CV of 7.9%, after a 3-day withdrawal period. The detection limit for the system used was estimated to be 0.4 ng, and the limit of quantitation for the method was estimated to be 2 ppb.
Determination of Lanthanum, Europium, and Ytterbium in Food Samples by Electrothermal Atomic Absorption Spectrometry
Authors: Miaokang Shen , Yinyu Shi
Published: February 2020

A method had been developed for the determination of lanthanum, europium, and ytterbium in food samples by using electrothermal atomic absorption spectrometry with a graphite furnace lined with tungsten foil. The proposed method provides higher sensitivity than inductively coupled plasma/atomic emission spectrometry (ICP/AES); the characteristic masses are 8.1 x 10-9 g for lanthanum, 3.9 x 10-11 g for europium, and 4.27 x 10,-12 g for ytterbium. The precision, accuracy, and interferences of the method were also investigated. The method can be used for the analysis of trace amounts of lanthanum, europium, and ytterbium in various foods without predissociation of the matrixes of the digested solutions. The results obtained by the method are in good agreement with those from ICP/AES.
Headspace Method for Rapid Determination of Methyl Bromide in Assorted Nut Samples
Authors: Daft James L
Published: February 2020

A headspace method has been developed for the rapid, safe determination of methyl bromide (MeBr) in raw and processed nuts. Fifty grams of frozen nut meats is blended 3 min at high speed in 200-250 mL aqueous solution in a sealed 1 L blender cup fitted with a septum port on its cover. The cup is equilibrated 10 min in a 25C water bath. Two 250 ±150 μL aliquots of the sample headspace gas are sequentially removed with a gas-tight syringe and injected into a dual column/ dual detector gas chromatograph. One determination is made with a GS-Q wide-bore capillary column and a Hall electrolytic conductivity detector, the other with a packed column, 20% OV-101 on Chromosorb W(HP), and a 63Ni electron capture detector. The average variation for the manual injections is about 5% for both column/detector systems. To prevent random emission of MeBr during the determination, dated standards, headspace wastes, and electron capture detection effluent are passed through liquid traps. The overall recovery of MeBr from fortified samples is about 40%; the coefficient of variation is 29%. Eighteen assorted nut samples were analyzed on both systems at a quantitation limit of ᑉ100 ng/g; no detectable MeBr was found.
Assessment of Fourier Transform Infrared Analysis of Milk
Authors: Van De Voort Frederick R , Sedman Jacqueline , Emo Gary , Ismail Ashraf A
Published: February 2020

A Nicolet 510 Fourier transform infrared (FTIR) spectrometer was modified to perform IR milk analyses by incorporating a temperature-controlled 37 µm CaF2 flow cell and a homogenizer into the analytical system. The unit was evaluated for its ability to predict the chemical values of calibration milks, and its performance was compared with that of a commercial filter-based IR milk analyzer (Multispec MK1). Conventional dual-wavelength multiple regression methods and whole-spectrum multivariate analysis techniques (classical least squares and partial least squares) were also compared for their predictive capabilities. We found that the prototype FTIR unit met AOAC standards for milk analyses and performed as well as or better than the filter instrument. The macro-programming capability of the FTIR software, which enables the user to combine strings of FTIR commands and parameters into a single command, allowed automation of data processing. The whole-spectrum multivariate analysis methods were able to provide total solids data directly in addition to fat, protein, and lactose. On the basis of this evaluation, FTIR appears to be a viable alternative means for performing milk analyses.
Determination of Nitroimidazole Metabolites in Swine and Turkey Muscle by Liquid Chromatography
Authors: Mallinson Edward T , Henry A Carolyn , Rowe Loyd
Published: February 2020

The method described can determine hydroxy dimetridazole and hydroxy ipronidazole in turkey and swine muscle tissue at levels of 2 ppb. After an initial extraction with ethyl acetate and subsequent evaporation, the samples are solvated in acid and back-extracted. A C18 solid-phase extraction is performed after neutralization of the acidic extract. The basis for quantitation was an external standard containing both analytes. After performing 10 recovery curves with blank control tissue spiked at 0, 1,2, and 4 ppb, the mean recoveries of hydroxy dimetridazole and hydroxy ipronidazole were 61.8 and 64.6%, respectively. Recovery variation was less than 20% for both analytes over all 10 curves. The performance of the extraction method was verified in tissues incurred through the dosing of live animals.
Liquid Chromatographic Determination of Vitamin D in Animal Feeds and Premixes
Authors: Agarwal Vipin K
Published: February 2020

A liquid chromatographic (LC) method has been developed for the determination of vitamin D (D2 + D3) in animal feeds and premixes. The sample is saponified with potassium hydroxide, and vitamin D is extracted with hexane and isomerized to isotachysterol with 10M HCI in 2-butanol. LC determination of isotachysterol to quantitate vitamin D is carried out on a reversed-phase column with acetonitrilemethanol (90 +10) as the mobile phase and ultraviolet detection at 301 nm. The detection limit of the method is 1 lU/g. This method can also be used for the determination of vitamin D2 and D3 separately.
Effect of the Limit of Detection on Exposure Assessment
Authors: Loftus Michele L , Barraj Leila M , Tomerliv J Robert
Published: February 2020

An important component in evaluating the risk from pesticides in our foods is estimating the dietary exposure from the pesticide. This paper examines the effect of the limit of detection (LOD) on dietary exposure assessment. When designing food surveys for the purpose of estimating exposure from residues in foods as eaten, the effect of the LOD on exposure assessment should be evaluated before commencement of the analytical phase of the food survey. The purpose of the evaluation is to determine the LOD required to adequately quantify human exposure. The evaluation entails either determining the level at which the LOD is low enough to obtain exposure estimates that fall in the acceptable range or the level at which further reduction of the LOD will not result in additional observable reduction in estimates of exposure. Models describing exposure as the product of consumption and the magnitude of the residue in food are presented. Residue data from controlled field studies are used as examples to determine the optimum LOD to use in a food survey for assessment of exposure from a chronic adverse health effect. A computer program, EXPOSURE 1®, based on the U.S. Department of Agriculture Nationwide Food Consumption Survey, is used to estimate dietary exposure.
Extractive Spectrophotometric Determination of Trace Amounts
of Sulfur Dioxide in Air
Authors: Kumar B S M , Balasubramanian N
Published: February 2020

A sensitive spectrophotometric method was developed for the determination of trace amounts of sulfur dioxide (SO2) in air after SO2 has been fixed in a buffered formaldehyde solution. The reaction of iodate with the fixed SO2 in the presence of an acid and an excess of chloride leads to the formation of ICI2 ions. The resulting ICI2 species forms an ionpair with pararosaniline cation; the product is extracted into isopentyl alcohol and measured spectrophotometrically at 560 nm. The color system obeys Beer's law over the range 0-40 μg SO2. The color is stable for 72 h from the time of extraction. The molar absorption coefficient of the color system is 4.5 x 103Lmol"1cm"1. The coefficient of variation is 3.6% for 10 determinations at 20 μg SO2. The effect of interfering gases on the determination is discussed. The method was applied to the determination of SO2 at low concentrations, and the results obtained were compared with the widely used West and Gaeke method. The method can be used to determine as low as 2 μg S02
Polyclonal Enzyme Immunoassay Method for Detection of Motile
and Non-Motile Salmonella in Foods: Collaborative Study
Authors: Feldsine Philip T , Falbo-Nelson Maria T , Hustead David L
Published: February 2020

A new enzyme immunoassay (EIA) method for detection of motile and non-motile Salmonella was examined in a multilaboratory collaborative study. This method uses a proprietary formulation of polyclonal antibodies to Salmonella and is controlled to maintain specificity. Sensitivity is enhanced with an additional antibody reaction designed to minimize false-negative reactions attributable to steric interference that can occur during conjugate binding in immunoassay procedures. Thirty-two laboratories participated in this evaluation, which included 6 food types: nonfat dry milk, dry egg, black pepper, soy flour, chocolate, and ground poultry. Of the 1020 samples analyzed, there was a 97.2% agreement rate between the EIA method and the AOAC/Bacteriological Analytical Manual(BAM) culture method, 967.26. False-negative rates for the 2 methods were comparable for all foods and all Salmonella levels except ground poultry, where the EIA method detected significantly more confirmed positive samples than did the AOAC/BAM method. Nineteen samples were positive by EIA but negative by the culture method, and 10 samples were negative by EIA but positive by the culture method
Gas Chromatographic Determination of Acaricide Danjiami
in Citrus and Soil
Authors: Yitong Lu , Yuzhong Xue , Jin Xu , Wei Yan
Published: February 2020

A method is described for determining total danjiami residues in citrus and soil. Danjiami and its metabolites are hydrolyzed to 2,4-dimethylaniline by ref luxing with acid/base, re-extracted with petroleum ether, and cleaned up with acid/base partition. Sample is then derivatized to the heptafluorobutyranilide and quantitated by electron capture gas chromatography. Theoretical detectable limits are 5 ppb for citrus pulp and soil and 1 ppb for citrus peel. Recoveries for control samples fortified with danjiami at 0.25-2.0 ppm averaged 82.4% for citrus and 82.8% for soil
Survey of Butyltin, Cyclohexyltin, and Phenyltin Compounds
in Canadian Wines
Authors: Forsyth Donald S , Weber Dorcas , Dalglish Karen
Published: February 2020

Butyltin, cyclohexyltin, and phenyltin compounds were extracted with 0.05% tropolone in pentane from enzymatically hydrolyzed wine samples. Methyl derivatives made by Grignard reaction were quantitated by gas chromatography (GC)/atomic absorption spectrometry (AAS). Wine samples contained <0.1-138 ng dibutyltin/mL. Lower levels of monobutyl- and tributyltin were also detected by GC/AAS. Polyvinyl chloride) (PVC) liner material used in some commercial transport tanks contained extractable butyltins. Imported wines sampled from these containers and Canadian wines blended with wine imported in PVC-lined tanks had considerably higher butyltin levels than did wines shipped in stainless steel. Analysis by GC/mass spectrometry confirmed the presence of butyltins in wine and PVC liner samples and, in addition, detected monophenyl- and monocyclohexyltin compounds at levels below the GC/AAS method detection limits of 0.04-0.05 ng Sn/mL
Simplified Method to Measure Suspensibility of Water-Dispersible Powder: Use of Microanalytical Techniques to Reduce Wastewater
Authors: Ogawa Masao , Ohtsubo Toshiro , Tsuda Shigenori , Tsuji Kozo
Published: February 2020

A method was developed for suspensibility of pesticides in the form of water-dispersible powders (WPs) as an alternative to CIPAC method MT 15.1. After the suspensibility study, the methods, along with several variations, were compared on the basis of reduction of waste, simplicity of the procedures used, and time required to measure suspensibility. WPs in this study were prepared by using fenitrothion and procymidone as representatives of liquid and solid active ingredients. The best method was obtained by modifying CIPAC MT 15.1 as follows: (a) A100 mL measuring cylinder was used instead of a 250 mL cylinder, (b) the process for preparing a suspension in a beaker was deleted, (c) the content of the active ingredient in the top 90% was analyzed instead of the bottom 10%, and (d) the process for evaporating water from a suspension removed by pipet from the top 90% was deleted. Suspensibility determined by this method showed good consistency with that determined by the original CIPAC method, and results were reproducible. Time required for determination of suspensibility and the amount of waste produced by this method was about 40% of that for the original CIPAC method. Furthermore, this method is suitable for WPs made with both liquid and solid active ingredients.
Organochlorine Pesticide Residues in Dairy Milk in and around Delhi
Authors: Mukherjee Irani , Gopal Madhuban
Published: February 2020

A survey of dairy milk and milk products in and around Delhi, India, was undertaken to monitor the levels of DDT and HCH. The survey revealed that pesticide residue levels in milk often exceeded the limits recommended by the Food and Agriculture Organization/World Health Organization Expert Committee. Maximum residue levels of total HCH in milk (fat/whole milk basis) has not yet been prescribed. The 15 samples of dairy milk and 4 samples of milk products analyzed had residue levels ranging from 0.022 to 0.166 μg/g for HCH and from 0.042 to 0.382 μg/g for DDT.
Specific Determination of Ethylene Oxide and Ethylene Chlorohydrin in Cosmetics and Polyoxyethylated Surfactants by Gas Chromatography with Electron Capture Detection
Authors: Sasaki Kumiko , Kijima Keiji , Takeda Mitsuharu , Kojima Shigeo
Published: February 2020

A simple specific determination method was developed for ethylene oxide (EO) and ethylene chlorohydrin (ECH) in cosmetics and surfactants. EO is desorbed from samples by using a nitrogen stream and absorbed into acidic potassium iodide solution, where it is converted to ethylene iodohydrin (EIH). Any remaining ECH in the samples is converted to EO by the addition of sodium hydroxide, and the desorption procedure is repeated with a fresh acidic potassium iodide absorbing solution. EIH is extracted with benzene and determined by gas chromatography with electron capture detection. EO and ECH contents in the samples are calculated from EIH results. Recoveries from water and shampoo samples were 70.3 ± 5.4 and 58.9 ± 1.2%, respectively, for EO and 66.3 ± 4.0 and 64.5 ± 4.6%, respectively, for ECH. Detection limits in 0.2-2.0 g samples were in the 0.005-0.03 μg/g range for EO and 0.01-0.07 μg/g for ECH. High levels of EO (30-394 μg/g as ECH) were found in 5 of 18 polyoxyethylated surfactant samples, but only small amounts (0.07-4.0 μg/g) of ECH were detected in the samples. EO was not detected in cosmetic samples tested, but ECH was present in small quantities (≤1.11 μg/g).
Liquid Chromatographic Determination of Aflatoxins in Animal Feeds and Feed Components
Authors: Yen Ivan Chang , Bidasee Keshore R
Published: February 2020

A method is described for the determination of af latoxins B1, B2, G1, and G2 in animal feeds and feed components by liquid chromatography (LC) with fluorescence detection. In this modified procedure, the aflatoxins are extracted from the samples with methanol-water (75 + 25), and the solution is vacuum- filtered through Whatman No. 541 filter paper. An aliquot of the extract is first defatted with petroleum ether, and then the aflatoxins are partitioned into chloroform. The chloroform extract is purified on a silica gel chromatographic column, aflatoxins B1 and G1 are derivatized by trif luoroacetic acid to their hemiacetals, and the aflatoxins are determined by reversed-phase liquid chromatography. Recoveries from 11 samples ranged from 90 to 98% for aflatoxins B1 and G1 (spiking range 2-25 ng/g) and B2 and G2 (spiking range 0.2-2.5 ng/g).
Gas Chromatographic Determination of Hydrocarbons in Crude Palm Kernel Oil
Authors: Tan Yew Ai , Kuntom Ainie
Published: February 2020

A method for the determination of hydrocarbons (HCs) in crude palm kernel oil (CPKO) is described. HCs are extracted from CPKO by passing through a silica gel column by using n-hexane as the eluting agent. The eluate is collected for analysis. Identification and confirmation of the HCs in the eluate are performed with the aid of a gas chromatograph equipped with a mass selective detector, and the HCs in CPKO are quantitated by comparison of peak areas with reference to an external standard, eicosane (C20H42). Recoveries and coefficients of variation for 5 samples of oil spiked with 1 - 300 μg/g eicosane were 70.0-86.6% and 3.5-13.2%, respectively. The method was used for the analysis of CPKO suspected of being contaminated with mineral oil.
Determination of Residual Imazethapyr in Soybeans by Gas Chromatography/Nitrogen-Phosphorus Detection
Authors: Mortimer Richard D , Weber Dorcas F
Published: February 2020

Imazethapyr, a recently introduced imidazolinone herbicide, is registered for use on soybeans and other legumes in the United States and Canada. Its maximum allowed residue level in soybeans is 0.1 ppm. A method was developed to allow the measurement of ≥0.01 ppm imazethapyr on soybeans. The method exploits the ready cyclization of the nonvolatile acid to the volatile imidazoisoindol-3,5-dione by using an excess of easily removed, watersoluble carbodiimide and the selectivity of gas chromatography with nitrogen-phosphorus detection. A simple cleanup on a diol-bonded silica minicolumn reduces the complexity of the soybean extract. The derivatization works equally well for other imidazolinone herbicide acids. Because imidazoisoindolediones have characteristic fragmentation patterns, they are useful for mass spectroscopic confirmation of suspected residues.