Showing papers in "Journal of AOAC International in 1999"
TL;DR: Results of a collaborative trial study involving 29 laboratories in 13 countries applying a method for detecting genetically modified organisms (GMOs) in food based on using the polymerase chain reaction to determine the 35S promotor and the NOS terminator for detection of GMOs are presented.
Abstract: European Commission, DG Joint Research Center, Institute for Health and Consumer Protection, Food Products Unit,I-21020 Ispra(Va), ItalyCollaborators: T. Borchers, G. Braunschweiger, U. Busch, E. Eklund, F.D. Eriksen, J. Fagan, A. Fellinger, H. Gaugitsch,D. Hayes, C. Hertel, H. Hortner, P. Joudrier, L. Kruse, R. Meyer, M. Miraglia, W. Muller, P. Philipp, B. Popping, R. Rentsch,J. Sawyer, M. Schulze, G. van Duijn, S. Vollenhofer, A. WurtzThis paper presents results of a collaborative trialstudy (IUPAC project No. 650/93/97) involving29 laboratories in 13 countries applying a methodfor detecting genetically modified organisms(GMOs) in food. The method is based on using thepolymerase chain reaction to determine the35S promoter and the NOS terminator for detectionof GMOs. Reference materials were produced thatwere derived from genetically modified soy beansand maize. Correct identification of samples con-taining 2% GMOs is achievable for both soy beansand maize. For samples containing 0.5% geneticallymodified soy beans, analysis of the 35S promoterresulted also in a 100% correct classification. How-ever, 3 false-negative results (out of 105 samplesanalyzed) were reported for analysis of the NOS ter-minator, which is due to the lower sensitivity of thismethod. Because of the bigger genomic DNA ofmaize, the probability of encounteringfalse-negative results for samples containing 0.5%GMOs is greater for maize than for soy beans. Forblank samples (0% GMO), only 2 false-positive re-sults for soy beans and one for maize were re-ported. These results appeared as very weak sig-nals and were most probably due to contaminationof laboratory equipment.
258 citations
TL;DR: Measurement of total nitrogen by Kjeldahl analysis is the historical reference method for determination of the protein content of dairy products and is used for both calibration and validation of alternative methods for protein determination.
Abstract: Measurement of total nitrogen by Kjeldahl analysis is the historical reference method for determination of the protein content of dairy products and is used for both calibration and validation of alternative methods for protein determination. Accurate evaluation of alternative methods is not possible if there is large uncertainty regarding the reference values. When Kjeldahl analysis is used to establish reference values, the performance of the Kjeldahl testing must be verified and within established expectations. Advice is given for Kjeldahl system optimization, evaluation of test results, and trouble-shooting. Techniques for successful Kjeldahl nitrogen analysis of dairy products other than milk are discussed.
218 citations
TL;DR: Results for total folates were lower than results obtained with microbiological methods, but use of a commercially available folate-binding protein for cleanup saved time and money and was effective.
Abstract: A liquid chromatographic (LC) method was elaborated for determining folates in foods. Folates were extracted by homogenizing in buffer and heat treatment. A portion was incubated with an enzyme preparation containing conjugase, amylase, and protease. After purification by affinity chromatography, folate monoglutamates were determined by reversed-phase LC with fluorescence and diode array detection. Gradient elution with phosphate buffer and acetonitrile was used to separate vitamers. The most abundant folate forms naturally present in foods were detected, including tetrahydrofolic acid, 5-methyltetrahydrofolic acid, and 5-formyltetrahydrofolic acid. 10-Formylfolic acid could be detected by applying a second fluorescence detector. Folic acid, used for fortification, might also be quantitated with this system. The difference between folate concentrations in sample extracts, with and without treatment of conjugase, is a measure of the quantity of polyglutamates in the food matrixes. An additional treatment with conjugase, amylase, and protease reflects the amount of matrix-bound folates. The LC system gave a linear response over the range 0-100 ng/mL. Detection limit for these compounds were 7 pg/mL for tetrahydrofolic acid and 5-methyltetrahydrofolic acid and 59 pg/mL for 10-formylfolic acid (signal-to-noise ratio > or = 3) when 100 microL was injected. Detection limits for 5-formyltetrahydrofolic acid and folic acid were 1 ng/mL. Repeatability relative standard deviation values for separate folates in 3 candidate Certified Reference Materials (CRMs)--mixed vegetables (CRM 485), pig liver (CRM 487), and whole-meal flour (CRM 121)--and a Certified Reference Material milk powder (CRM 421) varied from 3.3 to 21.0% for the concentration range 1.8-1440 micrograms/100 g. Recoveries ranged from 73 to 109%. Use of amylase and protease was advantageous. Use of a commercially available folate-binding protein for cleanup saved time and money and was effective. Results for 5-methyltetrahydrofolic acid were in good agreement with results obtained with other LC methods. Results for total folates were lower than results obtained with microbiological methods.
178 citations
TL;DR: A modified liquid chromatographic (LC) method for determining OA in green coffee was applied and OA contamination at about 0.03 ng/g was found in 56 of 383 wheat samples, 11 of 103 barley samples, 9 of 19 green coffee samples, and 9 of 13 roasted coffee samples.
Abstract: Ochratoxin A (OA) is a nephrotoxic and nephrocarcinogenic mycotoxin produced by Aspergillus and Penicillium species. It has been found mainly in cereal grains and coffee beans. The purpose of this study was to investigate the occurrence of OA in cereal grains and in coffee imported to the United States. A modified liquid chromatographic (LC) method for determining OA in green coffee was applied to wheat, barley, green coffee, and roasted coffee. The test sample was extracted with methanol-1% NaHCO3 (7 + 3), and the extract was filtered. The filtrate was diluted with phosphate-buffered saline (PBS), filtered, and passed through an immunoaffinity column. After the column was washed with PBS and then with water, OA was eluted with methanol. The eluate was evaporated to dryness, and the residue was dissolved in acetonitrile-water (1 + 1). OA was separated on a reversed-phase C18 LC column with acetonitrile-water-acetic acid (55 + 45 + 1) as eluant and quantitated with a fluorescence detector. Recoveries of OA from the 4 commodities spiked over the range 1-4 ng/g were 71-96%. The limit of detection was about 0.03 ng/g. OA contamination at > 0.03 ng/g was found in 56 of 383 wheat samples, 11 of 103 barley samples, 9 of 19 green coffee samples, and 9 of 13 roasted coffee samples. None of the coffee samples contained OA at > 5 ng/g; only 4 samples of wheat and 1 sample of barley were contaminated above this level.
141 citations
TL;DR: The present review emphasizes the analytical problems associated with aminoglycoside analysis as well as a wide variety of detection methods, including mass spectrometry, which have been used.
Abstract: Aminoglycosides are antimicrobial agents used frequently in treatment of human and animal diseases caused by aerobic, gram-negative bacteria. Because of the toxicity of these compounds, considerable effort has been attributed to analysis of aminoglycoside content in drug preparations, in serum and urine specimen in therapeutic drug monitoring, and in edible animal tissues in residue control. The present review emphasizes the analytical problems associated with aminoglycoside analysis. Screening methods based on microbiological and immunological procedures were briefly discussed. Gas chromatography and especially high-performance liquid chromatography appeared the most widely used chemical methods for the analysis of these compounds. Due to lack of volatility, chromophore, and hydrophility of aminoglycosides, most methods applied derivatization for enhancement of their chromatographic characteristics. The applicability and advantages of the various derivatization procedures were discussed in detail. A wide variety of detection methods, including mass spectrometry have been used. Packed column separation was generally used for gas chromatographic separation. In liquid chromatography, reversed phase, ion pair, ion exchange, and normal phase separation has been employed. Mass spectrometry, as a detection method, was discussed in detail. Extraction procedures from body fluids and tissues were emphasized. The performance and the operational conditions of the methods were described and detailed information of the data was provided also in table format.
98 citations
TL;DR: A method for detection, quantitation, and confirmation of more than 100 pesticides by gas chromatography with ion trap mass spectrometry (MS/MS) has been developed, making compound identification and confirmation clear, even with a relatively dirty food matrix.
Abstract: A method for detection, quantitation, and confirmation of more than 100 pesticides by gas chromatography (GC) with ion trap mass spectrometry (MS/MS) has been developed The sensitivity of this method for many analytes is equal to or lower than those of selective GC detectors such as flame photometric detectors and electrolytic conductivity detectors Using MS/MS, very low detection limits and good confirmation (1 precursor ion and 2 or more product ions) are achieved simultaneously The entire list of pesticides is screened with 2 injections per sample Samples are introduced onto the column by a temperature-programmed cold injection to maximize response Each pesticide is run with its own unique set of parameters, which fragment the compound, retaining only the precursor ion This ion is then refragmented to create a product spectrum The selectivity of MS/MS gives a very clean spectrum, making compound identification and confirmation clear, even with a relatively dirty food matrix If care is taken to maintain the injection port and guard column, this method can reliably identify and confirm more than 100 pesticides at the low parts-per-billion range
90 citations
TL;DR: Although OTA was detected in most samples from various countries, AFs were detected in the beer samples from only a limited number of countries where AF contamination might be expected to occur because of their warm climate.
Abstract: Analyses of ochratoxin A (OTA) and aflatoxins (AFs) in 94 imported beer samples from 31 producing countries and in 22 Japanese beer samples were performed by immunoaffinity column and reversed-phase liquid chromatography (LC) with fluorescence detection. Recoveries of OTA from beer samples spiked at 25 and 250 pg/mL were 86.1 and 88.2%, respectively. Recoveries of AFs were 98.4 and 98.9%, 95.4 and 95.5%, 101.2 and 97.8%, and 98.9 and 96.0%, respectively, from beer samples spiked at 4.1 and 41 pg AF B1, 4.45 and 44.5 pg AF B2, 4.7 and 47 pg AF G1, and 4.65 and 46.5 pg AF G2/mL. Detection limits were 1.0 pg/mL for OTA, 0.5 pg/mL for AFs B1 and B2, and 1.0 pg/mL for AFs G1 and G2. OTA was detected in 86 (91.5%) of 94 imported beer samples at a mean level of 10.1 pg/mL and in 21 (95.5%) of 22 Japanese beer samples at a mean level of 12.5 pg/mL. AF B1 was detected in 11 of 94 imported beer samples at a level of 0.5-83.1 pg/mL and in 2 of 22 Japanese beer samples at 0.5 and 0.8 pg/mL. Except for one beer sample from Peru, the samples contaminated with AFs were also contaminated with OTA. Although OTA was detected in most samples from various countries, AFs were detected in the beer samples from only a limited number of countries where AF contamination might be expected to occur because of their warm climate.
73 citations
TL;DR: The levels of selenium found in this study were generally lower than those reported in Finland but comparable withThose reported in some parts of the United States.
Abstract: Wet digestion using a mixture of nitric, sulfuric, and perchloric acids and an aluminum block digester effectively and rapidly decomposed meat samples for selenium determination by hydride generation atomic absorption spectrophotometry. Digestion did not require constant attention by an operator. Selenium recoveries (range, 94-105%) from National Institute of Standards and Technology standard reference materials and spiked samples were used to validate method accuracy. Coefficients of variation (CVs) of repeatability of in-house reference materials used for precision study were 6.4 and 5.6%, respectively, for seafood mix and mutton liver. Selenium levels in meat products from Brisbane markets varied widely: 0.042-0.142, 0.081-0.42, and 0.050-0.198 microgram/g (wet weight) respectively, for beef, chicken, and pork. Overall, selenium levels in manufactured meat ranged from 0.041 to 0.189 microgram/g. The levels of selenium found in this study were generally lower than those reported in Finland but comparable with those reported in some parts of the United States.
62 citations
TL;DR: In this article, the muscle tissue matrix is taken into account when plotting regression lines relating the quantity of amine to the biogenic amine/internal standard ratio, and it is shown that it changes during spoilage.
Abstract: Spoilage can be evaluated by separating and determining biogenic amines by various techniques, notably high-performance liquid chromatography. Previous studies have not taken into account how the muscle tissue matrix affects the assay. We demonstrate a matrix effect in plaice and whiting and show that it changes during spoilage. This effect should be taken into account when plotting regression lines relating the quantity of amine to the biogenic amine/internal standard ratio.
59 citations
TL;DR: Organophosphorus, dithiocarbamates, and some synthetic pyrethroids pesticides, which are commonly used in Egypt for pest control, were monitored, as well as persistent organochlorines, which had been prohibited from use several years ago.
Abstract: Organophosphorus, dithiocarbamates, and some synthetic pyrethroids pesticides, which are commonly used in Egypt for pest control, were monitored, as well as persistent organochlorines, which had been prohibited from use several years ago. Fruit and vegetable samples (397) were collected from 8 local markets and examined for 52 pesticides. Of all analyzed samples, 42.8% contained detectable residues, of which 1.76% exceeded their maximum residue limits (MRLs). The rates of contamination with the different pesticides were 0-86%. However, violation rates among contaminated products were very low, ranging from 0 to 4.6%. In general, organochlorine pesticide residues were not detected in most samples. Dithiocarbamate residues were found in 70.4% of 98 samples analyzed for dithiocarbamates, but only one grape sample had residues exceeding the MRL established by the Codex Committee on Pesticide Residues.
58 citations
TL;DR: Improved quality and efficiency of pesticide residue analysis were achieved by examining all aspects of the laboratory process and instrumental improvements, including new selective detectors, retention time locking, and mass spectrometry screening for all samples, provided the laboratory with efficient, reliable, and confirmed analytical results.
Abstract: Improved quality and efficiency of pesticide residue analysis were achieved by examining all aspects of the laboratory process. In an effort to eliminate methylene chloride hazardous waste, an acetonitrile extraction method, originally developed by the California Department of Agriculture, was modified and adopted. Sample size and solvent consumption were reduced with the new method. Custom glassware racks and disposable supplies reduced overall analysis time. Gravity-fed, solid-phase extraction simplified sample preparation and provided cleaner extracts for gas chromatographic analyses. Modifications to the method were made to achieve the ruggedness needed to maintain quality objectives during routine analysis. Instrumental improvements, including new selective detectors, retention time locking, and mass spectrometry screening for all samples, provided the laboratory with efficient, reliable, and confirmed analytical results.
TL;DR: The Personal OPLC Basic System 50 as discussed by the authors is an automated overpressured-layer chromatographic (OPLC) system that is suitable for analytical and semipreparative separations.
Abstract: A new automated overpressured-layer chromatographic (OPLC) system called the Personal OPLC Basic System 50 is suitable for analytical and semipreparative separations. The automatic microprocessor-controlled system ensures rapid and reproducible off-line isocratic and stepwise gradient separations. High external pressure (5 MPa) makes the sorbent layer more homogeneous, yielding more efficient off-line separation compared with those by early Chrompres chambers. A theoretical plate height of 10-30 μm can be achieved on an analytical high-performance thin-layer chromatographic (HPTLC) layer made of irregular silica gel with an average particle size of 5 μm if an optimal linear velocity (20-40 mm/min) and a nonviscous solvent system are used. On an analytical layer of 3 μm spherical silica gel, a theoretical plate height of 6-15 μm can be reached. Rapid analytical separations of resveratrol (1555 s) and xanthine by one(498 s) and two-directional (274 s) off-line developments were accomplished. On-line separation and detection combined with off-line sample application and fully on-line processing (including on-line sample application, separation, and detection) were fulfilled with a TLC plate for xanthine separation. Semipreparative isolation of xanthines was achieved through a fully on-line OPLC operating mode and scaled-up chromatography.
TL;DR: The procedure is rapid, precise, and quantitative and requires minimal preparation and minimal use of organic solvents and can be applied to routine surveillance programs.
Abstract: A multiresidue method for isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in milk is presented. The sensitivity of the method is adequate to meet the needs of regulatory agencies. The European Community established 100 micrograms/kg as the maximum residue limit (MRL) in milk for TC, CTC, and OTC. Recoveries exceeded 80% for all tetracyclines at all levels, with good precision. Correlation coefficients of standards curves for individual tetracyclines isolated from fortified samples ranged from 0.991 for CTC to 0.998 for OTC. Other antibiotics that might interfere with analysis did not interfere with elution times of OTC, TC, and CTC. The procedure is rapid, precise, and quantitative and requires minimal preparation and minimal use of organic solvents. It can be applied to routine surveillance programs. We can prepare 10 samples for analysis in about 1.45 h.
TL;DR: Findings do not support the hypothesis that mycotoxin contamination increases the risk of gastric cancer among those who consume fermented Chinese pancakes, and the mycotoxins were detected only at low levels, which did not increase with fermentation.
Abstract: Consumption of fermented, but not unfermented, corn pancakes has been linked with elevated stomach cancer mortality rates in rural Linqu County in Shandong Province, China. Previous surveys of fungal contamination of corn in China have detected fumonisins, which are mycotoxins produced by Fusarium moniliforme. To determine whether mycotoxins might account for the increased risk of cancer among those consuming fermented pancakes, we obtained specimens of corn, cornmeal, unfermented and fermented pancake batter, and cooked fermented pancakes from each of 16 households in Linqu County for analysis by the U.S. Department of Agriculture. Fumonisins B1, B2, and B3 were detected (> or = 0.5 microgram/g) in 19, 25, and 6% of the corn specimens, respectively, as well as in various corn products. No type A trichothecenes were detected; however, the type B trichothecenes deoxynivalenol and 15-acetyldeoxynivalenol were detected (> or = 0.5 microgram/g) in 58 and 17% of the corn specimens, respectively, and zearalenone was detected (> or = 0.5 microgram/g) in 15% of the cornmeal specimens. The mycotoxins were detected only at low levels (< 10 micrograms/g), which did not increase with fermentation. These findings do not support the hypothesis that mycotoxin contamination increases the risk of gastric cancer among those who consume fermented Chinese pancakes.
TL;DR: The interlaboratory validation of analytical procedures for the assay of urinary 3,5,6-trichloro-2-pyridinol (TCP) in the general Italian population is reported, and the Mann-Whitney U test showed that wine consumption was a statistically significant variable for urinary concentrations of TCP.
Abstract: The interlaboratory validation of analytical procedures for the assay of urinary 3,5,6-trichloro-2-pyridinol (TCP) in the general Italian population is reported. The determinations were performed by high-resolution gas chromatography (HRGS) with electron capture detection and HRGS with mass spectrometry (MS) in 2 laboratories. The urine samples were from 42 participants from 3 regions of Italy. The results were evaluated by interlaboratory quality control. Urinary TCP concentrations were above the detection limit (1.2 micrograms/L) in 88% of the population, with a mean detectable concentration [GM (GSD)] of 2.8 (1.9) micrograms/g creatinine (creat). (GM, geometric mean; GSD, geometric standard deviation.) The Mann-Whitney U test showed that wine consumption was a statistically significant variable (p < 0.05) for urinary concentrations of TCP. Analysis of variance of the logarithm of urinary TCP versus wine consumption and diet showed a statistically significant fit. The model used explained 30% of the total variance: wine consumption and diet accounted for 37 and 17% respectively of the explained variance.
TL;DR: A simple and rapid method was developed for determination of benomyl, diphenyl (DP), o-phenylphenol (OPP), thiabendazole (TBZ), chlorpyrifos, methidathion, and methyl parathion in whole oranges.
Abstract: A simple and rapid method was developed for determination of benomyl, diphenyl (DP), o-phenylphenol (OPP), thiabendazole (TBZ), chlorpyrifos, methidathion, and methyl parathion in whole oranges. These compounds were extracted from a mixture of samples and anhydrous sodium acetate with ethyl acetate. The ethyl acetate extract was concentrated and cleaned up by passing through tandem solid-phase extraction columns consisting of anion-exchange and primary/secondary amine bonded silica. The eluate was concentrated and volume was adjusted with methanol for subsequent liquid chromatography (LC) and gas chromatography (GC). Benomyl (as methyl-2-benzimidazole carbamate, MBC), DP, OPP, and TBZ residues were determined by LC with fluorescence detection. Recoveries at 3 fortified levels (0.1, 1, and 10 micrograms/g) ranged from 63.9 to 97.4%, with coefficients of variation (CVs) of 1.6 to 15.5%. Limits of detection (LODs) were 0.01 microgram/g for DP, OPP, TBZ and 0.05 microgram/g for benomyl. Chlorpyrifos, methidathion, and methyl parathion residues were determined by GC with flame photometric detection. Recoveries ranged from 90.4 to 97.0%, with CVs of 2.1 to 5.9%. LODs were 0.005 microgram/g for chlorpyrifos and methyl parathion, and 0.01 microgram/g for methidathion.
TL;DR: In 1997, the National Institute of Standards and Technology (NIST) released Standard Reference Material (SRM) 2383 Baby Food Composite, which can be used as a control material when assigning values to in-house control materials and when validating analytical methods for the measurement of proximates, vitamins, minerals, and trace elements in baby foods and similar matrixes.
Abstract: In 1997, the National Institute of Standards and Technology (NIST) released Standard Reference Material (SRM) 2383 Baby Food Composite. This SRM can be used as a control material when assigning values to in-house control materials and when validating analytical methods for the measurement of proximates, vitamins, minerals, and trace elements in baby foods and similar matrixes. The Certificate of Analysis for SRM 2383 provides certified and reference values for concentrations of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, beta-carotene, delta-tocopherol, gamma-tocopherol, alpha-tocopherol, retinol, and retinyl palmitate for 2 types of sample preparation--extraction and saponification. The assigned values were based on the agreement of measurements made by NIST and collaborating laboratories. The Certificate of Analysis also provides reference and information values for concentrations of proximates, minerals, and additional vitamins; assignment of these values is discussed in a companion paper (this issue, page 276).
TL;DR: To investigate the body burden of organochlorine pesticides and dioxins in Japanese women, 125 milk samples were collected and significant correlations were found among levels of beta-HCH, p,p'-DDE, total PCDD-TEQ, total PCsDD + PCDF, total coplanar polychlorinatedbiphenyl (CoPCB), and total TEQ except for less correlation between p, p-DDE and total PCDF- TEQ.
Abstract: To investigate the body burden of organochlorine pesticides and dioxins in Japanese women, 125 milk samples were collected from 41 mothers in 1994, 42 in 1995, and 42 in 1996 Of the 125 samples, 82 were from primipara mothers (first delivery) and 43 were from multipara mothers (second or later delivery) By using capillary gas chromatography with electron capture detection, beta-HCH and p,p'-DDE were detected as the major chlorine pesticides in human milk Average levels of beta-HCH and p,p'-DDE were 475 and 368 ng/g lipid, respectively, in primipara breast milk, 314 and 259 ng/g lipid in multipara breast milk, and 420 and 330 ng/g lipid in total breast milk Dieldrin, heptachor epoxide, oxychlordane, trans-chlordane, and cis-chlordane were detected at lower average levels of 3, 4, 34, 41, and 5 ng/g lipid, respectively By using high-resolution gas chromatography with mass spectrometric detection, dioxins were detected in all samples Average levels of total polychlorinated dibenzo-p-dioxin (PCDD), total polychlorinated dibenzofuran (PCDF), total PCDD + PCDF, total coplanar polychlorinatedbiphenyl (CoPCB), and total dioxin were 100, 78, 177, 99, and 275 TEQ (toxic equivalent) pg/g lipid, respectively, in primipara breast milk; 70, 58, 128, 73, and 201 TEQ pg/g lipid in multipara breast milk; and 89, 71, 161, 89, and 250 TEQ pg/g lipid in total breast milk In primipara breast milk, significant correlations were found among levels of beta-HCH, p,p'-DDE, total PCDD-TEQ, total PCDF-TEQ, total CoPCB-TEQ, and total TEQ except for less correlation between p,p'-DDE and total PCDF-TEQ Levels of these analytes also significantly increased depending on mother's age, except for total Co-PCB-TEQ For the correlation with food habit, the only positive correlation was between total PCDF-TEQs and fish intake
TL;DR: The levels of contamination with various organochlorine pesticides of different foods from 3 traditional markets were determined and consumption of the foods analyzed does not pose a risk to consumer health.
Abstract: The levels of contamination with various organochlorine pesticides (such as total HCH, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endosulfan, and total DDT) of different foods from 3 traditional markets were determined to estimate Taiwanese daily intake of organochlorine pesticides. Of the 18 organochlorine pesticides investigated, alpha-HCH, beta-HCH, lindane, delta-HCH, heptachlor, heptachlor epoxide, dieldrin, endrin, alpha-endosulfan, p,p'-DDE, and p,p'-DDT were detected at concentrations ranging from 0.26 to 10.2 ng/g wet weight. Contamination with organochlorine pesticides followed the order heptachlor > dieldrin > alpha-endosulfan > HCH isomers > heptachlor epoxide > DDT. Frequencies of detection of organochlorine pesticide residues ranged from 2.0 to 52.3%. alpha-Endosulfan was the most frequently detected organochlorine pesticide in the foods analyzed, followed by heptachlor epoxide (47.6%) and alpha-HCH (38.9%). Estimated daily intakes (EDIs) of organochlorine pesticides from foods were 1.137 micrograms for total HCH, 2.147 micrograms for heptachlor, 0.702 microgram for heptachlor epoxide, 0.624 microgram for endosulfan, 0.098 microgram for cyclodiene, and 0.541 microgram for total DDT. These EDIs were only 0.075% of the acceptable daily intake (ADI) for lindane, 47.5% of ADI for heptachlor and heptachlor epoxide, 0.045% of ADI for total DDT, and 1.01% of ADI for aldrin and dieldrin. Therefore, consumption of the foods analyzed does not pose a risk to consumer health.
TL;DR: Patulin was eluted with 3 mL 2% acetonitrile in anhydrous ethyl ether and was determined by reversed-phase liquid chromatography with UV detection at 276 nm and recoveries ranged from 93 to 104% in test samples spiked at 20-100 micrograms/L.
Abstract: Patulin, a mold metabolite, is commonly found in rotting apples. Some countries regulate patulin at levels ranging from 30 to 50 micrograms/L. Most analytical methods for patulin in apple juice include liquid-liquid partitions. A solid-phase extraction method has been developed for apple juice and unfiltered apple juice in the United States. A portion of the test sample (5 mL) was passed through a macroporous copolymer cartridge and was washed with 1 mL 1% sodium bicarbonate and then with 1 mL 1% acetic acid. Patulin was eluted with 3 mL 2% acetonitrile in anhydrous ethyl ether and was determined by reversed-phase liquid chromatography with UV detection at 276 nm. Recoveries ranged from 93 to 104% in test samples spiked at 20-100 micrograms/L.
TL;DR: Fatty acid methyl esters of pure triglyceride standards, oils, and fat from dry matrixes were formed by transesterification using sodium methoxide in methanol-hexane to produce FAMEs free of interferences and easily quantitated by GC or confirmed by GC/mass spectrometry.
Abstract: Fatty acid methyl esters (FAMEs) of pure triglyceride standards, oils, and fat from dry matrixes were formed by transesterification using sodium methoxide in methanol-hexane. FAMEs were produced by direct addition of sodium methoxide-hexane to samples and heating to simultaneously extract and transesterify acyl lipids. FAMEs were quantitated by capillary gas chromatography (GC) over a fatty acid concentration range of 0 to 1.7 mg/mL (r > or = 0.9997). Total fat was calculated as the sum of individual fatty acids expressed as triglyceride equivalents, in accordance with nutrition labeling guidelines. Saturated, polyunsaturated, and monounsaturated fats were calculated as sums of individual free fatty acids. Absolute recoveries determined from individual fatty acids in test samples ranged from 69.7 to 106%. Recoveries (relative to the C13:0 internal standard) for individual fatty acids in test samples ranged from 95 to 106%. Reproducibility was constant at each fatty acid level in the reaction mixture (n = 5, coefficient of variation [CV] < 2%). Absolute recovery determined from the sum of total fatty acids in standard reference material (SRM) 1846 (powdered infant formula) was 96.4%. Analysis of SRM 1846 gave results that agreed closely with the certified fat and fatty acid values. Analysis of commercial infant formula gave results that were comparable to those obtained with AOAC Method 996.01. The direct extraction methylation procedure is rapid, and the transesterification of acyl lipids to form FAMEs is complete within 15 min. Classical saponification and refluxing are not required. This method provides FAMEs free of interferences and easily quantitated by GC or confirmed by GC/mass spectrometry (MS). Unambiguous MS identification of individual FAMEs derived from pure standards, SRM 1846, and powdered infant formula product was obtained.
TL;DR: The combination of retention time locking, GC-AED, database search, and GC/MS can be a powerful tool for identifying pesticides in a complex matrix.
Abstract: Fruit and vegetable extracts were screened for over 400 pesticides by gas chromatography with atomic emission detection (GC-AED) and an experimental database. A technique called retention time locking was used to match GC-AED and GC with mass spectrometry (MS) retention times to those of the database. Samples were analyzed for sulfur, nitrogen, phosphorus, and chlorine by GC-AED. Possible pesticides were suggested by database search and identified by GC/MS. Forty-four pesticide standards were analyzed to determine the precision of retention time matching and the accuracy of the database search. Analytical retention times matched database retention times within 0.32 min. Using elemental criteria, the database search identified the correct compound for 41 of 44 pesticide standards. For blind spikes of fruit and vegetable extracts, the database suggested 22 of 26 spiked pesticides as matches. Nineteen were identified by GC/MS. The combination of retention time locking, GC-AED, database search, and GC/MS can be a powerful tool for identifying pesticides in a complex matrix.
TL;DR: The study showed that NIRS is a potentially useful technique for evaluating the composition of unhomogenized ovine milk.
Abstract: Analysis by near-infrared spectroscopy (NIRS) was investigated as a means of predicting quality parameters of ovine milk Calibration equations were developed with samples of ovine milk obtained from a flock of Manchega and Lacaune dairy ewes at different stages of lactation for a wide variation in milk composition Prediction equations for milk protein, fat, and total solids content were developed by use of reflection or transflection methods to measure absorbance values Accuracies of measurements were compared R2 (squared multiple correlation coefficient) values were satisfactory in most cases The highest R2 value for milk protein content (092) was obtained in transflectance mode with unhomogenized milk The highest R2 values for fat (099) and total solids (098-096) content were obtained in both a transflectance mode without sample conditioning and in a transflectance mode with milk homogenized at 40 degrees C To validate the calibration, an independent set of 40 milk samples was used The best r2 (simple correlation coefficient) values for protein, fat, and total solids were 092, 097, and 092, respectively The study showed that NIRS is a potentially useful technique for evaluating the composition of unhomogenized ovine milk
TL;DR: The results indicate the effectiveness of monitoring, as well as the need for constant surveillance and control, especially at critical control points (sites of import, primary storage, etc.), to prevent unfit products from entering the Cyprus market.
Abstract: Aflatoxins (AFs) B1 ,B 2 ,G 1, and G2 in locally produced and imported foodstuffs (nuts, cereals, oily seeds, pulses, etc.) were monitored and controlled systematically and effectively from 1992‐1996. Samples (peanuts, pistachios, etc.) with total AFs above the Cyprus maximum level (ML) of 10 μg/kg fluctuated between 0.7 and 6.9%. The results indicate the effectiveness of monitoring, as well as the need for constant surveillance and control, especially at critical control points (sites of import, primary storage, etc.), to prevent unfit products from entering the Cyprus market. The control included sampling, retainment, analysis, and destruction of foodstuff lots with AF levels above MLs. The highest incidence of aflatoxin contamination was observed in peanut butter (56.7%) and the highest level of AF B1 was found in peanuts (700 μg/kg). Levels of AF M1 in raw and pasteurized milk analyzed in 1993, 1995, and 1996 were within both the Cyprus ML (0.5 μg/L) and the lower ML (0.05 μg/L) of some European countries. Only 12% of samples had detectable levels of AF M1. Analyses were performed by immunochemical methods. When recoveries were lower than 80%, the AF levels were corrected for recovery.
TL;DR: A capillary electrophoretic method was developed to analyze simultaneously most citrus juice components in a single procedure, giving information on quality, freshness, and possible adulteration of the product.
Abstract: A capillary electrophoretic method was developed to analyze simultaneously most citrus juice components in a single procedure After filtration, sample components are separated with an uncoated capillary tubing and a 35 mM sodium borate buffer (pH 93) containing 5% (v/v) acetonitrile Analyses were run at 21 kV and 23 degrees C Compounds monitored regularly were the biogenic amine synephrine, some flavonoids (didymin, hesperidin, narirutin, neohesperidin, and naringin), the polyphenol phlorin, 3 UV-absorbing amino acids (tryptophan, phenylalanine, and tyrosine), ascorbic acid, an unidentified peak generated by heat and storage, and the preservatives sorbate and benzoate that can be added to citrus products Separation can be achieved in 20 min, and each compound can be subsequently quantitated Didymin, narirutin, and phlorin peaks were used with an artificial neural network to assess the volume of added pulp wash, a by-product of juice preparation This method allows rapid monitoring of citrus juices, giving information on quality, freshness, and possible adulteration of the product Similar procedures could be used to monitor other fruit juices and quantitate diverse juice blends
TL;DR: An analytical method is presented for precise identification and quantitation of 29 specific polychlorinated biphenyl (PCB) congeners and 15 chlorinated pesticides in human serum for high-resolution gas chromatographic analysis.
Abstract: An analytical method is presented for precise identification and quantitation of 29 specific polychlorinated biphenyl (PCB) congeners and 15 chlorinated pesticides in human serum. Analyte surrogates PCB 30, PCB 204, 2,2',4,4',5,5'-hexabromo-biphenyl, perthane, alpha-hexachlorocyclohexane, and dichlorobenzophenone were added to each sample. The serum was extracted with an organic solvent and separated by adsorption chromatography into 3 elution fractions for high-resolution gas chromatographic analysis. Each fraction was analyzed by dual-column capillary chromatography followed by electron capture detection. Two capillary columns, DB-5 and DB-1701, with different polarities were used to increase selectivity for each analyte. Quantitation was performed by selecting 2 sets of calibration standard mixtures and 1,2-dichloronaphthalene as an internal standard. Mean recoveries ranged from 39 to 126% for selected analytes and from 31 to 88% for surrogates. Detection limits for specific congeners and pesticides are reported. Typical chromatographic profiles of calibration standard mixtures, as well as a human sample, are illustrated. Verification of each analyte is assessed, and results of analyses of selected human samples and quality control criteria used to ensure data validity also are presented.
TL;DR: A high-performance liquid chromatographic method for the simultaneous determination of tilmicosin, tylosin, spiramycin, and its major metabolite neospiramycin was developed that is suitable for porcine, bovine, and poultry muscles.
Abstract: A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of tilmicosin, tylosin, spiramycin, and its major metabolite neospiramycin was developed that is suitable for porcine, bovine, and poultry muscles. Macrolide residues were extracted from muscle with acetonitrile, fat was removed by liquid-liquid extraction with isooctane, and the extract was then cleaned on Bond Elut C18 cartridges. The HPLC separation was performed on an Inertsil ODS3 C18 column (150 x 4 mm) with 0.05% trifluoroacetic acid-acetonitrile in a gradient mode. Two different chromatographic gradients were used for tilmicosin-tylosin and spiramycin-neospiramycin, and the detection wavelengths were 287 and 232 nm, respectively. The method was validated from 1/2 the maximum residue limit (MRL) to 4 times the MRL with pork muscle samples. Mean recoveries were 60, 63.5, 51, and 42% for tilmicosin, tylosin, spiramycin, and neospiramycin, respectively. The detection limits are 15 micrograms/kg for tilmicosin and tylosin, 30 micrograms/kg for spiramycin, and 25 micrograms/kg for neospiramycin. Linearity, precision, and accuracy of the method were also tested.
TL;DR: A separation scheme for the determination of sugars and starch in processed food was developed and results were compared with values listed on the "Nutrition Facts" panel for that food.
Abstract: A separation scheme for the determination of sugars and starch in processed food was developed. It is based on AOAC Method 985.29 for total dietary fiber with these modifications: carbohydrate starches are separated into soluble and insoluble fractions before they are hydrolyzed; acetonitrile is used instead of ethanol to separate sugars from enzyme-resistant carbohydrates, proteins, and other macromolecules; and a solid-phase extraction filter is included to remove substances that interfere with high-performance liquid chromatography (HPLC). Recovery studies indicate a > 97% sugar recovery. Twenty foods were analyzed. After enzymatic hydrolysis, fructose, glucose, sucrose, maltose, and lactose were extracted and determined by HPLC using a refractive index detector. Starch content was calculated from the increase in the amount of glucose. The results were compared with values listed on the "Nutrition Facts" panel for that food. The analyzed amounts of sugars and starches were 73-96% of declared values.
TL;DR: A biosensor based on surface plasmon resonance (SPR) measurement was developed for use in an immunoassay for detection of sulfamethazine (SMZ) in milk and no cross-reactivity of antibodies with other antibiotics was found.
Abstract: A biosensor based on surface plasmon resonance (SPR) measurement was developed for use in an immunoassay for detection of sulfamethazine (SMZ) in milk. The biospecific surface was a carboxymethyl dextran-modified gold-surface sensor chip to which SMZ was covalently bound. The assay was based on inhibition of the binding of polyclonal antibodies to immobilized SMZ by SMZ in the sample. The SPR response changed inversely in relation to the antibiotic concentration in the sample. Calibration curves were constructed for SMZ in buffer and in milk at a concentration which included the maximum residue limit (0 to 200 micrograms/kg). The analysis time per sample varied from 8 to 30 min. Different flow rates and antibodies were modified alternatively during the study to assess their influence on the performance of the assay. The active antibody concentration was calculated at approximately 1880 and 180 nM for the antibody anti-SMZ 1 and the antibody anti-SMZ 2, respectively. No cross-reactivity of antibodies with other antibiotics was found. Under optimal conditions, the detection limits in milk for SMZ were 8 and 1.7 micrograms/kg, respectively, for antibody 1 and antibody 2, at a flow rate of 20 microL/min.