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A simple and effective sample enrichment method of frozen zone melting liquid-liquid extraction was optimized and validated for the analysis of trace N-nitrosodimethylamine (NDMA) in beer samples. The method was based on high pressure liquid-liquid extraction with a low temperature frozen step. The
Levels of N-nitrosodimethylamine (NDMA) were determined in 112 samples of 2,4-dichlorophenoxyacetic acid, (2,4-D), formulated as the dimethylamine salt, collected over a 2 year period from products on the Canadian market. A sample aliquot is partitioned with dichloromethane, and the co-extracted
Ten laboratories participated in a collaborative study of a method for the determination of N-nitrosodimethylamine (NDMA) in nonfat dry milk. NDMA is eluted with dichloromethane from a mixture of Celite, acidic sulfamic acid, and nonfat dry milk (all packed in a chromatography column), concentrated
N-nitrosodimethylamine (NDMA) is a probable human carcinogen of concern that has been identified as a drinking water contaminant. U.S. Environmental Protection Agency Method 521 has been developed for the analysis of NDMA and 6 additional N-nitrosamines in drinking water at low ng/L concentrations.
The effect of a single administration of aromatic hydrocarbons (AHCs) on the metabolic activity responsible for the biotransformation of dichloromethane (DCM) to carbon monoxide (CO) was investigated using adult female rats. In rats treated orally with benzene (1.5 ml kg-1), toluene (2.0 ml kg-1) or
A simple, rapid method for the extraction of N-nitrosodimethylamine (NDMA) from drinking and surface waters was developed using Ambersorb 572. Development of an alternative method to classical liquid-liquid extraction techniques was necessary to handle the workload presented by implementation of a
A method is presented, wherein concentrated dichloromethane extracts from malt, beer, and nonfat dried milk powder containing N-nitrosodimethylamine (NDMA), and fried dry-cured and pump-cured bacon containing NDMA and N-nitrosopyrrolidine (NPYR) undergo 3N HClO4-Celite microcolumn cleanup followed
The carcinogen N-nitrosodimethylamine (NDMA) may be quantitated routinely at ultratrace (ng/L) levels in drinking water or contaminated groundwater. The aqueous sample is passed through a preconditioned Empore C18 filter disk to remove neutral nonpolar species and then extracted continuously
A gas-liquid chromatographic (GLC) procedure is described for the determination of low ppb levels of N-nitrosodimethylamine (NDMA) in beer. The sample is treated with sulfamic acid under acidic conditions followed by alkalinization with dilute KOH, distillation at atmospheric pressure, extraction of
A new solid-phase extraction procedure extracts N-nitrosodimethylamine (NDMA) at part-per-trillion (ng/L) concentrations from aqueous samples using a C18 (reversed-phase) membrane extraction disk layered over a recently introduced carbon-based extraction disk. The reversed-phase disk removes
A simple and rapid analytical method has been developed for the determination of N-nitrosodimethylamine (NDMA) in amine salts of phenoxy herbicide formulations of 2,4-D and MCPA, plus mixtures of these with mecoprop and dicamba amine salts. Sample preparation consists of direct extraction using
A new isotope dilution gas chromatography/chemical ionization/tandem mass spectrometric method was developed for the analysis of carcinogenic hydrazine in drinking water. The sample preparation was performed by using the optimized derivatization and multiple liquid-liquid extraction techniques.
A sensitive procedure, microwave-assisted extraction (MAE) coupled dispersive micro solid-phase extraction (D-μ-SPE), was developed to extract N-nitrosodimethylamine (NDMA) and other six volatile N-nitrosamines (NAms) from meat products. Parameters affecting the efficiency of MAE and D-μ-SPE were
Volatile N-nitrosamines in infant latex rubber pacifiers were determined using a modification of a previously described dichloromethane extraction procedure, followed by gas chromatography/thermal energy analysis. Under an interagency agreement between the National Center for Toxicological Research
A simple direct extraction method has been developed for rapid determination of volatile N-nitrosamines in rubber nipples and pacifiers. It consists of overnight extraction of the sample with dichloromethane in the presence of ascorbyl palmitate for N-nitrosation inhibition, filtration of the