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W Fiddler

Publications and source records attributed to W Fiddler.

At least 37 records · Page 2Linked to original sources
PubMed1982

Chemiluminescence detection of nitrite in nonfat dried milk powders.

Determination of nitrite in nonfat dry milk powders by chemiluminescence detection was compared with a colorimetric method specifying Griess reagents. The chemiluminescent technique requires no sample preparation, is free from apparent interferences, and is sensitive to 25 ppb nitrite. Statistical analysis shows no difference at P = 0.05 between the colorimetric and chemiluminescent methods, based on the analysis of 16 commercial nonfat dry milk samples.

Animals↗
PubMed1982

Gas-liquid chromatographic-thermal energy analyzer determination of N-nitrosodimethylamine in beer: collaborative study.

The GLC/TEA method for N-nitrosodimethylamine (NDMA) in beer was studied collaboratively by 13 laboratories from 7 countries. Collaborators were asked to analyze a total of 10 randomly labeled samples of beer consisting of the following duplicates: a naturally contaminated commercial beer; a beer extremely low (ca 0.1 ppb) in NDMA; and the low NDMA beer spiked with 0.5, 1.9, and 5.0 ppb NDMA. The pooled repeatability and reproducibility coefficients of variation (CV) for all samples were 17% and 27%, respectively. However, when data from 2 laboratories (outliers) were omitted, the corresponding CV values improved considerably (11% and 15%, respectively). Variance analysis showed the presence of a significant laboratory-sample interaction when all data were used for analysis, but this interaction disappeared when data from the 2 outlying laboratories were excluded. The pooled percent recovery of the overall method (omitting outliers) was 101.4 +/- 3.5. All the laboratories detected NDMA in the low NDMA beer. The method was adopted official first action.

Beer↗
PubMed1982

Confirmatory method for N-nitrosodimethylamine and N-nitrosopyrrolidine in food by multiple ion analysis with gas chromatography-low resolution mass spectrometry before and after ultraviolet photolysis.

A confirmatory procedure is described for determining N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) in bacon, beer, and malt by gas chromatography-low resolution quadrupole mass spectrometry (GC-MS). The presence of 3 monitored ions, m/z 30, 42, and 74 for NDMA, and m/z 30, 42, and 100 for NPYR, before and disappearance after photolysis under UV light at 365 nm without quantitation of peak areas was considered confirmatory evidence for their presence. The extracts, obtained by mineral oil distillation methods for bacon and malt, and dry column methods for bacon and beer, underwent cleanup procedures before capillary GC-MS analysis. Less than 100 ng nitrosamine in the total extract, or approximately 2 ng NDMA or 3 ng NPYR injected into the GC-MS instrument, can be confirmed by this method. This technique should also be applicable for other volatile nitrosamines.

Animals↗
PubMed1982

Mineral oil vacuum distillation method for nitrosamines in fried bacon, with thermal energy analyzer: collaborative study.

Nine laboratories participated in a collaborative study of a method for determining 6 nitrosamines, dimethylnitrosamine, diethylnitrosamine, dibutylnitrosamine, nitrosopiperidine, nitrosopyrrolidine, and nitrosomorpholine, in the 5-17 ppb range. The coefficients of variation for repeatability were 10.8, 8.5, 10.4, 8.5, 8.7, and 7.8% with corresponding coefficients of variation for reproducibility of 16.4, 12.0, 13.6, 10.8, 11.2, and 10.3% and recoveries of 89.6, 91.6, 84.7, 90.0, 89.6, and 88.1%, respectively. The method was adopted official first action.

Animals↗
PubMed1982

Dual column chromatographic method for determination of N-nitrosothiazolidine in fried bacon.

A dual column chromatographic procedure is described that permits the determination of N-nitrosothiazolidine (NTHZ), a newly identified nitrosamine, and N-nitrosopyrrolidine (NPYR), the principal volatile nitrosamine, in the same fried bacon sample. The procedure used an acid-Celite, Celite, sodium sulfate column followed by a partially deactivated basic alumina column to isolate NTHZ from bacon for subsequent quantitation by gas chromatography with a thermal energy analyzer (GC-TEA). A limited intralaboratory study gave standard deviations for repeatability and reproducibility of 1.20 and 1.55 ppb, respectively. The recovery of N-nitrosothiomorpholine, the internal standard added at the 10 ppb level, was 93.3 +/- 6.03%. The method is also free from artifactual nitrosamine formation.

Animals↗
PubMed1978

Alpha-tocopherol: uses in preventing nitrosamine formation.

alpha-Tocopherol has been evaluated as a nitrite scavenger for the prevention of nitrosamine formation in a model system and under practical conditions. alpha-Tocopherol was found to react with nitrosating agents in both lipophilic and aqueous environments. The use of alpha-tocopherol was shown to inhibit aminopyrene-nitrite induced hepatotoxicity in rats and to reduce the amount of NDMA formed in cigarette smoke. Of primary interest is the finding of a significant reduction of NPYR formation in fried bacon. Nitrosamine inhibition was greater with alpha-tocopherol used in combination with sodium ascorbate than with sodium ascorbate alone.

Animals↗
PubMed1977

Determination of N-nitrosoproline at the nanogram level.

Two sensitive detection systems are described for the quantitative determination of a nonvolatile nitrosamine, nitrosoproline. One procedure involves denitrosation followed by derivatization of amino product, proline, with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). The highly fluorescent NBD-proline compound formed is then identified and quantitated by either thin-layer chromatography or high-pressure liquid chromatography (HPLC). In the second system, the volatile methyl ester of the intact nitrosoproline is prepared, then detected by gas-liquid chromatography (GLC), and confirmed by combined gas-liquid chromatography and mass spectrometry (GLC-MS). Both methods permit the quantitative detection of less than 10 ng of nitrosoproline. However, the HPLC fluorescence technique is approximately ten times as sensitive as the GLC method.

Chromatography, Gas↗