Determination of ten N-nitrosoamino acids in cured meat products.

A rapid, sensitive, and accurate solid-phase extraction method was developed for the measurement of 10 N-nitrosoamino acids (NAAs) in cured meat products. In the procedure, the comminuted meat was mixed with sulfamic acid and Celite, and then added to a glass column containing anhydrous sodium sulfate. The column was washed with pentane, and the NAAs were eluted with ethyl acetate. The eluate was concentrated, then derivatized with diazomethane followed by acetic anhydride-pyridine reagent. The NAA methyl esters and their acylated hydroxy derivatives were separated by gas chromatography on a DB-5 fused silica capillary column and quantitated with a thermal energy analyzer, a chemiluminescence detector specific for nitric oxide derived from the thermal denitrosation of nitrosamines. Recovery of 10 of the NAAs exceeded 75% at the 10 ppb level. The method is applicable to a wide range of cured meat products.

The effect of combined treatment with potassium dichromate and maleic acid on renal function in the rat.

Subthreshold doses of potassium dichromate (K2Cr2O7) have been shown to enhance or potentiate the nephrotoxic effects of mercuric chloride and citrinin. The mechanism of this effect is unknown. The purpose of this study was to examine the phenomenon further by investigating the interaction of K2Cr2O7 with maleic acid, a nephrotoxicant with an action though to be different from those above. Male rats were housed in stainless steel metabolism cages and received a single intraperitoneal injection of maleic acid (300 mg/kg). K2Cr2O7 (10 mg/kg s.c.) or the combination of maleic acid plus K2Cr2O7. While treatment with either agent alone produced only minimal alterations in renal function, the combination of agents produced marked changes in 24 h urine volume, glucose excretion and osmolality. Water consumption was unaffected by the combined treatment. A marked decline in the capacity of renal slices to accumulate both organic anions (p-aminohippurate) and cations (tetraethylammonium) was observed after treatment with both substances. Modifications in renal and hepatic non-protein sulfhydryl content also were observed. These results suggest that K2Cr2O7, as was observed with both mercury and citrinin, enhanced or potentiated the nephrotoxic effects of maleic acid, probably in the proximal tubule, the principal site of glucose reabsorption and organic ion secretion.

HPLC method for the simultaneous determination of pilocarpine, isopilocarpine, pilocarpic acid and isopilocarpic acid.

A high-performance liquid chromatographic method suitable for the determination of pilocarpine, isopilocarpine, pilocarpic acid and isopilocarpic acid is described. The column used is a Spherisorb-CN bonded phase at 25 degrees C. An aqueous solution of triethylamine (0.1%, v/v) at pH 2.5 is used as mobile phase. Peak detection is by UV absorption at 220 nm. The elution orders are found to be pilocarpic-isopilocarpic acids with a resolution of 9 and K' of 5 and 6, respectively, isopilocarpine-pilocarpine with a resolution of 1.8 and K' of 13 and 13.5, respectively, the peaks being symmetrical.

Rapid gas chromatographic method for determining ethyl carbamate in alcoholic beverages with thermal energy analyzer detection.

A rapid column elution method has been developed for the determination of ethyl carbamate (EC) in alcoholic beverages. The beverage is mixed with Celite and packed in a column containing deactivated alumina capped with a layer of sodium sulfate. EC is then eluted with methylene chloride. The method, using a gas chromatograph-thermal energy analyzer with a nitrogen converter for detection and quantitation of EC, has been applied to a variety of alcoholic beverages. Recoveries +/- standard deviations of EC in wine and whisky fortified at the 20 and 133 micrograms/kg (ppb) levels averaged 87.3 +/- 5.3 and 88.7 +/- 3.6%, respectively. The method has a limit of detection of 1.5 ppb. Gas chromatography/mass spectrometry/mass spectrometry was used to confirm the identity and quantitation of EC in selected beverage extracts.

Analysis of piperazine drug formulations for N-nitrosamines.

A quantitative method is described for the measurement of N-mononitrosopiperazine (NPIP) and N,N'-dinitrosopiperazine (DNPIP) in drug formulations containing piperazine, using a gas chromatograph interfaced to a thermal energy analyzer (GC/TEA). The method has detection limits of 20 ppb for NPIP and 12 ppb for DNPIP. In a survey of 6 products available on the Canadian market, all contained NPIP at levels of 0.38-15.3 micrograms NPIP/g piperazine and none contained any detectable amount of DNPIP.