Method for determination of acephate, methamidophos, omethoate, dimethoate, ethylenethiourea and propylenethiourea in human urine using high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry.

Because of increasing concern about widespread use of insecticides and fungicides, we have developed a highly sensitive analytical method to quantify urine-specific urinary biomarkers of the organophosphorus pesticides acephate, methamidophos, omethoate, dimethoate, and two metabolites from the fungicides alkylenebis-(dithiocarbamate) family: ethylenethiourea and propylenethiourea. The general sample preparation included lyophilization of the urine samples followed by extraction with dichloromethane. The analytical separation was performed by high-performance liquid chromatography (HPLC), and detection by a triple quadrupole mass spectrometer with and atmospheric pressure chemical ionization source in positive ion mode using multiple reaction monitoring and tandem mass spectrometry (MS/MS) analysis. Two different Thermo-Finnigan (San Jose, CA, USA) triple quadrupole mass spectrometers, a TSQ 7,000 and a TSQ Quantum Ultra, were used in these analyses; results are presented comparing the method specifications of these two instruments. Isotopically labeled internal standards were used for three of the analytes. The use of labeled internal standards in combination with HPLC-MS/MS provided a high degree of selectivity and precision. Repeated analysis of urine samples spiked with high, medium and low concentration of the analytes gave relative standard deviations of less than 18%. For all compounds the extraction efficiency ranged between 52% and 63%, relative recoveries were about 100%, and the limits of detection were in the range of 0.001-0.282 ng/ml.

Differential handling of urea and its analogues suggests carrier-mediated urea excretion in freshwater rainbow trout.

The possible presence of urea transport mechanisms in the gill and kidney of the freshwater rainbow trout (Oncorhynchus mykiss) was investigated in vivo by comparing the branchial and renal handling of analogues acetamide and thiourea with the handling of urea. Trout were fitted with indwelling dorsal aortic catheters and urinary catheters and injected with an isosmotic dose of [(14)C]-labeled urea analogue (acetamide or thiourea) calculated to bring plasma analogue concentrations close to plasma urea concentrations. Urea and analogue concentrations were significantly greater in the urine than in the plasma. Branchial clearance rate of acetamide was only 48% of urea clearance, whereas the clearance of thiourea was only 22%, a pattern that was also observed in branchial uptake of these substances and was similar to our previous observations in toadfish and midshipmen. The renal secretion clearance rates of urea and acetamide were similar, and on average, both substances were secreted on a net basis, although reabsorption did occur in some cases. In contrast, thiourea was neither reabsorbed nor secreted by the kidney tubule. The secretion clearance rates of both acetamide and urea were well correlated with the secretion clearance rates of Na(+), Cl(-), and water, whereas there was no relationship between thiourea and these substances. The pattern of acetamide, thiourea, and urea handling by the gill of the trout is similar to that found in the gills of the midshipman and the gulf toadfish and strongly suggests the presence of a UT-type facilitated diffusion urea transport mechanism. The pattern of differential handling in the kidney is unlike that in the gill and also unlike that in the kidney of the midshipman and the gulf toadfish, suggesting a different mechanism. In addition, renal urea secretion occurs against a concentration gradient, suggesting the involvement of an active transport mechanism.

Simultaneous analysis of urinary 2-thiothiazolidine-4-carboxylic acid and thiocarbamide as a biological exposure index for carbon disulfide exposure.

The objectives of this study were to develop optimal analytic methods for detecting urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) and thiocarbamide simultaneously and to evaluate the usefulness of these metabolites to a biological exposure index (BEI) for carbon disulfide (CS2) exposure. For this experiment, synthesized TTCA and thiocarbamide were used. The synthesized TTCA was identified by infrared spectrophotometer, nuclear magnetic resonance spectrometer and thin layer chromatography. The recovery rates of both metabolites were calculated to find the optimum analytical method. The amounts of urinary TTCA and thiocarbamide were measured by using an ultraviolet detector connected to high performance liquid chromatography (HPLC) after the administration of CS2 (350, 700 mg/kg) into Sprague-Dawley rats intraperitoneally. The maximum absorbance wave lengths for TTCA and thiocarbamide were 272 and 236 nm, respectively. Ethyl acetate extraction with NaCl as a salting-out reagent was used as a simultaneous extraction method for these metabolites. HPLC conditions for these metabolites included using a NH2 column, 50 mM KH2PO4: acetonitrile (85:15) and pH 3. Excreted amounts of urinary TTCA and thiocarbamide were increased significantly following CS2 administration. TTCA, which was already adopted as a BEI for CS2 by the American Conference of Governmental Industrial Hygienists (ACGIH), seems to be a more useful BEI for CS2 exposure than thiocarbamide. However further studies are needed to increase analytical efficiency before thiocarbamide can be adopted as a BEI and to apply this analytic method for simultaneous analysis of these metabolites in workers exposed to CS2.

Simultaneous analysis of urinary 2-thiothiazolidine-4-carboxylic acid and thiocarbamide as a biological exposure index for carbon disulfide exposure

The objectives of this study were to develop optimal analytic methods for detecting urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) and thiocarbamide simultaneously and to evaluate the usefulness of these metabolites to a biological exposure index (BEI) for carbon disulfide (CS2) exposure. For this experiment, synthesized TTCA and thiocarbamide were used. The synthesized TTCA was identified by infrared spectrophotometer, nuclear magnetic resonance spectrometer and thin layer chromatography. The recovery rates of both metabolites were calculated to find the optimum analytical method. The amounts of urinary TTCA and thiocarbamide were measured by using an ultraviolet detector connected to high performance liquid chromatography (HPLC) after the administration of CS2 (350, 700 mg/kg) into Sprague-Dawley rats intraperitoneally. The maximum absorbance wave lengths for TTCA and thiocarbamide were 272 and 236 nm, respectively. Ethyl acetate extraction with NaCl as a salting-out reagent was used as a simultaneous extraction method for these metabolites. HPLC conditions for these metabolites included using a NH2 column, 50 mM KH2PO4: acetonitrile (85:15) and pH 3. Excreted amounts of urinary TTCA and thiocarbamide were increased significantly following CS2 administration. TTCA, which was already adopted as a BEI for CS2 by the American Conference of Governmental Industrial Hygienists (ACGIH), seems to be a more useful BEI for CS2 exposure than thiocarbamide. However further studies are needed to increase analytical efficiency before thiocarbamide can be adopted as a BEI and to apply this analytic method for simultaneous analysis of these metabolites in workers exposed to CS2.

Metabolism of 4-[1-(2-fluoro-4-biphenylyl)ethyl]-2-methylaminothiazole (SM-8849) in rats.

Metabolism of 4-[1-(2-fluoro-4-biphenylyl)ethyl]-2-methylaminothiazole (SM-8849), a novel immunomodulatory agent, in rats was investigated. By co-chromatography with authentic samples, desmethylated (SM-8800) p-hydroxylated (SL-5512) and desmethylated-p-hydroxylated SM-8849 (SL-5515) were detected in the bile. Thermospray mass spectrometry (TSP-MS) analysis of five metabolites isolated from the bile revealed molecular ions of both conjugates (glucuronides and a sulfate) and their aglycones. Aglycone structures were determined by comparison of their product spectra with those of authentic standards. Further analyses of conjugation sites were carried out by 1H-NMR including differential NOE. As a result, the sulfate of SL-5515 (5515-S), the N-glucuronides of SL-5512 and SM-8849 (5512-NG and 8849-NG, respectively), the glucuronide of SL-5512 (5512-G) and the O-glucuronide of 4-hydroxy-3-methoxy-SM-8849 (CatOMe-OG) were identified. In addition, N-methylthiouras was identified in urine by LC/MS/MS.

Thin-layer polarographic detector for the high-performance liquid chromatographic detection of thiourea derivatives.

A polarographic thin-layer detector for high-performance liquid chromatography, was devised. The detector has a sandwich structure with a working surface area of the mercury electrode of 0.25 mm2. The detector was applied to the direct amperometric detection and for detection with reactivation of the electrode surface by voltage pulses. It is shown that the latter detection mode is suitable for the determination of compounds that form insoluble or complex mercury salts, e.g., thiourea. Thiourea and its derivatives can be separated and determined in a wide concentration range and the detection limit for thiourea corresponds to 2 ng injected. Thiourea can be determined directly in urine.

[Urinary excretion of thioamine compounds in oncological patients]. / Ekskretsiia tioaminosoedinenii a mochoi u onkologicheskikh bol'nykh.

Using iodine-azide method, it was possible first to quantify the concentration and amount of the excretion of thiamine compounds in the diurnal urine of patients. The concentration of thioketones in human urine is shown to be 11--15 mg equivalents of thiourea per 1 ml urine, that is an order of magnitude lower than the threshold of sensitivity of the reaction with selenonic acid. It was found that the amount of thioketones excretion per day and their concentration in 1 ml of oncological patients' urine statistically do not differ from the corresponding values in the urine of patients with non-oncological diseases.

The action of pitressin on solute permeability of the rabbit nephron in vivo.

The isotopic equilibration of urea, thiourea, and inulin between urine and plasma was determined in rabbits in the presence or absence of antidiuretic hormone (ADH). Animals were anesthetized with ethanol and permitted to reach steady state after completion of surgery. Tracer was then administered by intraarterial infusion in such a manner that a high constant specific activity in plasma was rapidly attained. Urine flow was kept independent of ADH by addition of mannitol. Urea/creatinine clearance ratios and the accumulation of urea in renal medulla and papilla also remained unaffected by ADH. Under these conditions, thiourea and inulin at all times approached equilibrium, at similar rates. In the absence of ADH, urea also equilibrated at a rate similar to that of inulin. The addition of ADH, however, significantly prolonged the delay before urinary urea reached the high constant specific activity of plasma urea. These observations are interpreted in terms of a specific effect of the hormone on the solute permeability of the nephron.