Optimization study for the reversed-phase ion-pair liquid chromatographic determination of nicotine in commercial tobacco products.

The availability of published methods for the determination of nicotine in commercial tobacco products based on state-of-the-art chromatographic methods is limited. Nicotine is a diprotic base with pKa's of 3.12 (pyridine ring) and 8.02 (pyrrolidine ring). Other monoprotic and diprotic bases are also present in commercial tobacco including anatabine, nornicotine, anabasine, and cotinine. In this paper, the chromatography of nicotine and the minor tobacco alkaloids under reversed-phase ion-pairing conditions is thoroughly studied. The results of this study are used to understand the retention mechanisms of the tobacco alkaloids, to examine their observed elution order with respect to fundamental analyte properties (size, functionality, and acid-base strength), and to select optimum chromatographic conditions for the determination of nicotine in commercial tobacco products.

Determination of 4-hexylresorcinol in crab meat.

A method is described for determining 4-hexylresorcinol in crab meat. 4-Hexylresorcinol is used to prevent melanosis in shrimp, and the same use has been proposed for crab meat. Because 4-hexylresorcinol may be added illegally to crab meat as a preservative, consumer protection requires that residues of the compound be monitored in crab meat. 4-Hexylresorcinol is extracted from crab meat with acetonitrile. After dilution with water, the extract is passed through a C18 solid-phase extraction column and 4-hexylresorcinol is eluted from the column with ethanol. The compound is determined by reversed-phase liquid chromatography with diode array detection at 206 nm. Limit of quantitation is 1.0 microgram/g. Mean recovery in the range 1-20 micrograms/g is 89%, with a relative standard deviation of 6.3.

N,N'-diethyl-m-toluamide (m-DET): analysis of an insect repellent in human urine and serum by high-performance liquid chromatography.

A procedure for monitoring m-DET in human urine and serum is described. m-DET is removed from the urine specimen by partitioning into diethyl ether, but solid-phase extraction is used to remove it from human serum. The urine and serum m-DET values are determined by HPLC with a UV detector. The limit of detection was 0.09 micrograms/mL in urine and 0.09 micrograms/g for serum. The percent of m-DET recovered from human urine spiked between 0.50 and 8.00 micrograms/mL was 90 +/- 5.4%. For human serum spiked between 0.25 and 10.00, the percent recovered was 96 +/- 5.9%. The pooled relative standard deviations (RSD) for spiked matrices were 0.06 for urine and 0.06 for serum.

Immune responses of cynomolgus monkeys to phthalic anhydride.

Four groups of four Macaca fascicularis monkeys were administered 10 consecutive weekly subcutaneous injections of 2 mg aluminum hydroxide plus one of the following: 200 micrograms of phthalic anhydride (PA)-monkey serum albumin (PA-MSA, group 1); 200 micrograms of PA dissolved in ethanol-saline (EtOH-sal, group 2); 200 micrograms of MSA (group 3); or EtOH-sal alone (group 4). Direct intracutaneous tests to PA-MSA, PA-EtOH-sal, MSA, and EtOH-sal were applied at biweekly intervals throughout the course of the immunization. Serum-specific IgG to PA-MSA and specific IgE to PA-MSA were determined at 2-week intervals according to the ELISA and RAST methods, respectively. The prevalence of cutaneous sensitivity to PA-MSA in the PA-MSA-immunized group (group 1) was significantly greater after 4 and 6 (p less than 0.01) and 8 and 10 (p less than 0.05) weeks, compared with the other treatment groups. Significantly elevated (p less than 0.01) PA-MSA-specific IgG was also observed in monkeys in group 1 compared with the other treatment groups. No significant changes in PA-MSA RAST or total IgE were observed in any group during the study. These results indicate that parenteral sensitization to PA in subhuman primates requires the presence of new antigenic determinants formed by PA on protein carriers.

Analyses of ethylene glycol monoalkyl ethers and their proposed metabolites in blood and urine.

Glycol ethers are known to produce embryotoxic and teratogenic effects in a variety of animal species. In addition, testicular edema and tubular atrophy have been reported. The health effects of this class of compounds are not known in humans, despite the fact that these solvents are widely used in industry. In order to evaluate potential effects in humans, it is first necessary to estimate exposure in the workplace (environmental monitoring). However, in the case of glycol ethers traditional air monitoring may be ineffective because of the low volatility of these solvents and the possible significant exposure via the skin. Biological monitoring can be used to estimate glycol ether uptake by all routes of exposure. The compounds can be measured in blood or their metabolites quantitated in urine. These procedures are suggested for measuring 2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol in blood. In addition, tentative procedures have been developed to measure the oxidized acidic metabolites, methoxyacetic acid and ethoxyacetic acid in urine as possible indices of exposure. All procedures have detection limits of less than 11 parts per million. These procedures are ready to be validated in workers exposed to these solvents.

Metabolic and health consequences of occupational exposure to polychlorinated biphenyls.

In surveys of three groups of workers occupationally exposed to polychlorinated biphenyls (PCBs) serum PCB concentrations were quantitated as lower chlorinated biphenyls (L-PCBs) and higher chlorinated biphenyls (H-PCBs). Serum L-PCB and H-PCB concentrations were many times greater among workers employed in power capacitor manufacturing than exposed areas. Statistically significant positive correlations of symptoms suggestive of mucous membrane and skin irritation, of systemic malaise, and altered peripheral sensation were noted with increasing concentrations of serum PCB. No clinical abnormalities attributable to exposure to PCB were observed. Serum PCB concentrations were positively and significantly correlated with glutamic-oxalacetic transaminase (SGOT), serum gamma-glutamyl transpeptidase (GGTP), and plasma triglyceride, and inversely correlated with plasma high density lipoprotein-cholesterol. These correlations were present across all study sites. These findings are indicative of PCBs' physiological effect on the liver, whose long-range health significance is unknown. Nevertheless, the consistent positive association of serum PCB with plasma triglyceride and negative association with plasma HDL-cholesterol may have long-term cardiovascular consequences.

Analysis of formic acid in air samples.

The method reported here is for formic acid in air. Air containing formic acid is drawn through a midget impinger containing 15 ml of 0.1 N NaOH at a rate of one liter per minute for 42 minutes. An aliquot from the impinger is treated with an equal volume of ethanol-sulfuric acid mixture in a gastight reaction vial to produce ethyl formate. Because ethyl formate is volatile, an analysis of its vapor contained in the vial (headspace analysis) can be performed. The ethyl formate is analyzed by gas chromatography and its quantity is proportional to the quantity of formic acid contained in the reaction vial. With a relative standard deviation of 11 percent the method is precise enough for evaluating airborne formic acid at 0.1 of Threshold Limit Value of 9 mg/m3.