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Biomedical subjects

G W Diachenko

Publications and source records attributed to G W Diachenko.

At least 19 recordsLinked to original sources
PubMed2006

Rapid quantitative and qualitative confirmatory method for the determination of monofluoroacetic acid in foods by liquid chromatography-mass spectrometry.

A rapid quantitative method and a qualitative confirmatory method for the determination of monofluoroacetic acid (MFA) in complex food matrices are presented. The quantitative method utilizes a water extraction, solid phase extraction clean-up and liquid chromatography-mass spectrometry (LC-MS) for determination of MFA. This method showed a high degree of specificity, detecting MFA in all of the spiked samples, while none of the unfortified samples tested positive for MFA. Spike recoveries were high in all matrices analyzed, varying from 85 to 110%, and comparable at low (2mg/L) and high (20mg/L) spiking levels. Repeatability tests at the low spiking levels yielded RSDs of less than 5% for all matrices analyzed. The qualitative confirmatory method developed is conceptually different from the quantitative method, ensuring that both methods would not be subject to the same interferences. The method uses the formation of the hydrazide of MFA through derivatization with 2-nitrophenylhydrazine. This derivatization is well established for the determination of carboxylic acids, but this is the first application to the determination of MFA. The derivatization yield was matrix dependent, however the limit of detection (LOD) (0.8microg/L) was sufficient to confirm the presence of MFA in all spiked matrices. Repeatability tests at the low spiking levels yielded RSDs of approximately 7% for all matrices analyzed.

Chromatography, Liquid↗
PubMed2004

LC-UV and LC-MS analysis of food and drink products containing kava.

A method for the determination of six kava lactones, methysticin, dihydromethysticin, kawain, dihydrokawain, yangonin and desmethoxyyangonin, in solid foods and beverages has been developed. Solid samples were prepared using methanol extraction, while beverages were extracted using a separate solid phase extraction (SPE) method. After sample preparation, the extracts were analysed using LC-UV or atmospheric pressure photoionization (APPI) LC-MS in the positive mode. Using the method, 10 beverage products, two chocolate products, three unbrewed tea products, three dietary supplements and a drink mix product were analysed. The results obtained using the LC-UV were comparable to those obtained using APPI-LC-MS for most products. Using the SPE method in conjunction with LC-MS, individual kava lactones were detected in drink products at ppb concentrations. Concentrations of total kava lactones ranged between 135-0.035 mg per serving in the food and beverage products tested and between 40-61 mg per serving for the dietary supplement products tested. Results of these analyses as well as extraction efficiency and reproducibility data are reported.

Beverages↗
PubMed2003

Determination of 1,3-dichloropropanol in soy and related sauces by using gas chromatography/mass spectrometry.

A gas chromatography/mass spectrometry method for 3-MCPD in foods and food ingredients was modified for the determination of 1,3-DCP in soy and related sauces. The method was validated by using a blank soy sauce. The detection limit, quantitation limit and recoveries were determined, and identities were confirmed by mass spectrometry on the basis of analyses of test portions spiked with 1,3-DCP at 10, 25, 50 and 100 ng g(-1). The spiked test portions were quantitated by using an internal standard calibration curve. For the spiked test portions, the mean internal standard-corrected recovery for 1,3-DCP was 100% with a relative standard deviation of 1.32%. The limits of detection and quantitation were determined as 0.055 and 0.185 ng g(-1), respectively. The method also was compared with a headspace GC/MS method recently developed by the UK's Central Science Laboratory. Results from the method comparison showed that the recoveries for the spiked test portions, as well as the amounts of 1,3-DCP found in the retail products, were comparable.

Condiments↗
PubMed2003

Survey of chloropropanols in soy sauces and related products.

A survey of soy sauces and related products available in the USA was conducted to determine the levels of 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) in these products. Fifty-five retail samples were purchased and analysed for 3-MCPD. 3-MCPD determinations were made according to a gas chromatography/mass spectrometry method validated by a collaborative trial. Eighty-five per cent of the samples analysed contained greater than the detection limit of 0.005 ppm (microg g(-1)) for 3-MCPD. Thirty-three per cent contained greater than 1 ppm; the highest level was 876 ppm 3-MCPD. Thirty-nine of the samples analysed for 3-MCPD also were analysed for 1,3-DCP by using a modified method developed and validated in-house. Fifty-six per cent of the samples analysed for 1,3-DCP contained greater than the detection limit of 0.055 ppb (ng g(-1)) for 1,3-DCP; the highest level was 9.8 ppm 1,3-DCP. Products manufactured in Asia contained the highest chloropropanol levels.

Carcinogens↗
PubMed1997

Ethyl carbamate levels resulting from azodicarbonamide use in bread.

Azodicarbonamide (ADA), a dough conditioner, is an additive approved in the US up to a maximum of 45 mg/kg in flour. The addition of 45 mg/kg of ADA was investigated and found to increase the ethyl carbamate (EC) content of commercially prepared breads by 1-3 micrograms/kg. A similar increase in EC was observed in breads baked in the laboratory with a bread machine. The increase in EC levels appears to depend on a variety of factors, most notably the concentration of ADA added and the time of fermentation. The addition of 20 mg/kg ADA caused only a slight increase, if any, in commercial products but a 2.3 micrograms/kg increase of EC in breads baked with a bread machine. When 100 mg/kg of ascorbic acid was added along with ADA, smaller EC increases were observed. Addition of urea was also found to enhance the EC content of the bread. Toasting, which was previously shown to increase EC levels, caused even larger increases when ADA or urea had been added.

Azo Compounds↗
PubMed1994

Heterocyclic aromatic amine content of selected beef flavors.

Previous work has shown that meat extracts contain potent mutagenic and/or carcinogenic heterocyclic aromatic amines (HAAs). Because meat extracts and some beef flavors are produced from similar precursors and processing steps, the beef flavors may also contain HAAs. This study analyzed 24 commercial beef flavors and 2 food-grade beef extracts for creatine and creatinine concentrations, mutagenic activity and HAA concentrations (IQ, MeIQ, MeIQx, DiMeIQx, Glu-P-1, Glu-P-2 and PhIP). The creatine and creatinine levels of the flavors ranged from 0 to 73 and from 0 to 21 mg/g (dry wt.), respectively. The mutagenic activities of the flavors ranged from 0 to 3200 Salmonella typhimurium TA98 revertants/g (dry wt.). No direct relationship was found between creatine and/or creatinine concentrations and mutagenic activities. However, flavors with high creatine (> 1.5 mg/g) or creatinine (> 2 mg/g) levels exhibited higher mutagenic activities than did flavors with low levels of these compounds. Flavors with high mutagenic activities (> 1500 revertants/g) contained measurable amounts of HAAs. Three flavors contained MeIQx (7.2-21.2 ng/g [dry wt.]) and one contained DiMeIQx (4.2 ng/g [dry wt.]).

Animals↗
PubMed1977

Gas-liquid chromatographic headspace technique for determination of vinyl chloride in corn oil and three food-simulating solvents.

A gas-liquid chromatographic headspace technique for the determination of vinyl chloride (VC) in corn oil, 50% ethanol, 3% acetic acid, and n-heptane is described. These food-simulating solvents and the corn oil are placed in septum-sealed bottles and heated to 90 degrees C, and aliquots of headspace vapor are injected into a gas-liquid chromatograph equipped with a flame ionization detector. VC may be quantitated at concentrations of 1 ppb or less. This technique was used to measure the migration of VC into corn oil and 50% ethanol from 2 unplasticized polyvinyl chloride sheets containing 0.28 and 0.44 ppm residual monomer.

Chromatography, Gas↗
PubMedDate not supplied

Sulphite stabilization and high-performance liquid chromatographic determination: a reference method for free and reversibly bound sulphite in food.

A high-performance liquid chromatographic (HPLC) post-column reactor combination has been developed for the determination of sulphite (free and reversibly bound) in 15 different foods. The foods were treated with a pH 5.1 buffered aqueous 2% formaldehyde solution to convert the labile sulphite to the relatively stable hydroxymethylsulphonate. Reverse-phase ion-pairing HPLC with a post-column detector consisting of an initial reaction with KOH followed by colorimetric reaction with Ellman's reagent buffered at pH 6.3 were used for separation and quantitation. The photometric detector at 412 nm quantitated the strongly absorbing 3-carboxy-4-nitrothiophenolate anion, the product of the sulphite reaction with Ellman's reagent. The recovery at levels of 5-100 ppm as sulphur dioxide was greater than 90% by reverse isotope dilution assay. Repetitive analysis of a single grape juice extract containing 20 ppm SO2 showed a relative standard deviation of 2.2%.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Residues of volatile halocarbons in margarines.

Findings of residues of volatile halocarbons (VHCs) such as 1,1,1-trichloroethane, trichloroethylene and tetrachloroethylene in margarine are reported. VHCs were determined by a headspace gas chromatographic method with electron capture detection. Identity was confirmed by headspace gas chromatography-mass spectrometry for some of the higher level (100-5000 ppb) residues. A total of 70 stick, soft and diet soft margarines were purchased in the Washington, DC, metropolitan area. In addition, margarines and margarine ingredients were collected from 19 production lines. These products plus the adhesives used in the packaging were examined. Levels of VHCs ranging from 5 to 100 ppb (ng/g) were found in many of the margarines. The highest concentrations of any individual VHC (tetrachloroethylene at 1-5 ppm) were found in margarines obtained from a supermarket located next to a dry cleaner. Possible sources of VHC residues are discussed.

Chromatography, Gas↗
PubMedDate not supplied

Determination of free and reversibly bound sulphite in foods by reverse-phase, ion-pairing high-performance liquid chromatography.

The reaction of sulphite with formaldehyde to form hydroxymethylsulphonate (HMS), which is very stable under the controlled conditions of this assay, was used as the first step in an analytical procedure to determine foodborne sulphite. The effect of mobile-phase pH on the stability of HMS during high-performance liquid chromatography was studied. It was found that on-column HMS dissociation to formaldehyde and bisulphite increased with the pH of the mobile phase; therefore the relatively low pH 4.7, at which the dissociation of HMS was approximately 2%, was selected for the analysis. In addition, the release of sulphite from its reversibly bound forms in wine and other foods was examined as a function of the pH of the extraction medium by following the appearance of HMS formed from the reaction of the freed sulphite with formaldehyde. The rate of dissociation of the reversibly bound sulphite was relatively slow at pH 3 but very rapid at pH 7. This difference in kinetics was exploited to develop a procedure to determine free and reversibly bound sulphite in food. The method was challenged by post-reagent spiking studies, i.e. adding the sulphite spike after the food has been blended with the sulphite-protective formaldehyde solution but before proceeding with the remainder of the assay. An average recovery of 100% with a standard deviation of 5.2% (n = 45) was realized at levels of 5, 10 and 20 ppm by weight as sulphur dioxide. Recovery of the sulphite added as the bisulphite addition product of acetaldehyde, a model compound for reversibly bound sulphite, was 95%.

Animals↗
PubMedDate not supplied

Comparison of two clean-up methodologies for the gas chromatographic/mass spectrometric determination of low nanogram/gram levels of polynuclear aromatic hydrocarbons in seafood.

The March 1989 oil spill in Alaska prompted the Food and Drug Administration (FDA) to conduct a thorough investigation of clean-up methodologies aimed at determining low ng/g (ppb) levels of polynuclear aromatic hydrocarbons (PAHs) in seafood. The clean-ups from a modified FDA method and a National Marine Fisheries Service (NMFS) method were evaluated on the basis of the determination of 18 PAHs at levels ranging from 1 to 5 ppb by gas chromatography/mass spectrometry. In the modified FDA method, seafood extracts were purified by a liquid-liquid partition followed by a three-step elution through silica, alumina, and C18 solid-phase extraction cartridges. In the NMFS method, seafood extracts were purified by column chromatography through a deactivated silica gel/alumina column and a gel permeation high performance liquid chromatography column. Both methods quantitated 18 PAHs at levels ranging from 1 to 5 ppb. With the exception of naphthalene, average recoveries based on internal deuterated standards ranged from 73 to 144% for the modified FDA method and 63 to 106% for the NMFS method.

Gas Chromatography-Mass Spectrometry↗
PubMedDate not supplied

Determination of free glutamic acid in a variety of foods by high-performance liquid chromatography.

A survey of free glutamic acid levels in a variety of foods was conducted. The foods were analysed by high-performance liquid chromatography (HPLC). Free glutamic acid was extracted from the food with 0.02 M potassium phosphate with subsequent precipitation of other food components with acetone. Impurities were removed by passing the extract through a C-8 or C-18 reversed-phase solid-phase extraction column. The free glutamic acid was derivatized with phenylisothiocyanate, and the derivative was separated by HPLC with detection at 254 nm. Free glutamic acid levels ranged from not found (< 20 ppm) in some spices to as high as 89% in another spice.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Screening method for the gas chromatographic/mass spectrometric determination of microgram/litre levels of bromate in bottled water.

Bromate can be formed as a by-product of ozone treatment that is sometimes used for the disinfection of municipal water supplies and bottled waters. The US Environmental Protection Agency has proposed a maximum contaminant level (MCL) of 10 micrograms/l for bromate in public drinking water. Should the proposed MCL for bromate become final, it may then be considered for adoption as a bottled water quality standard by the US Food and Drug Administration. This paper reports the development of a gas chromatographic/ mass spectrometric (GC/MS) method for the determination of parts-per-billion (microgram/l) levels of bromate (BrO3-) in bottled water. The GC/MS method was validated by using distilled and deionized Milli-Q water; detection limits, quantitation limits, and recoveries were determined and identities were confirmed by MS on the basis of analyses of test portions fortified with BrO3- at 0.8, 3.8, 7.7, 15, and 46 micrograms/l. The method also was evaluated on the basis of recoveries determined for two commercial brands of bottled water fortified with BrO3- at 3.8 and 7.7 micrograms/l and two commercial brands fortified at 0.8, 3.8, and 7.7 micrograms/l. For the Milli-Q water, recoveries ranged from 100 to 121%; for the fortified commercial products, recoveries ranged from 87 to 115%. The limits of detection and quantitation were determined to be 0.4 and 0.7 microgram/l, respectively. Several commercial brands of bottled water were analysed, and BrO3- was found in these products at levels ranging from none to 38 micrograms/l.

Bromates↗