GLC determination of nylidrin in human urine samples

A method for the detection of nanogram quantities of nylidrin in human urine is described. The method involves beta-glucuronidase hydrolysis, extraction with chloroform, derivatization by silylation, and GLC determination. The suitability of the method was tested by analysis of urine samples of subjects after oral ingestion of nylidrin hydrochloride.     

New colorimetric method for quantitative determination of protein in urine

Total urinary protein is rapidly precipitated at room temperature by tannic acid. The tannic acid/protein precipitate, dissolved in aqueous triethanolamine/ferric chloride solution, gives a purple-violet color of high absorptivity. Absorbance at 510 nm is linearly related to concentration from 0.05 to 1.50 A for a protein content of 0.05 to 1.50 g/liter, and less than 5 mg/liter can be detected. The CV and analytical recovery ranged from 0.5 to 1.8% and 98 to 103%, respectively. Nonprotein urinary constituents do not interfere.     

Kinetic urine creatinine determination with the Gemsaec analyzer

A rapid automated method for urinary creatinine with the Jaffé reaction is described. Interferences by protein, glucose and ketones are circumvented by the reaction rate kinetics. The precision and accuracy of this centrifugal method on the ENI-Gemsaec analyzer are comparable to the manual end-point Jaffé reaction with deproteinization and to the common Auto-Analyzer technique.     

Amylase thermolability in body fluids

The thermolability of amylase was measured in saliva, pancreatic juice, urine, adult and neonatal sera. The mean percentage thermolability from these fluids was 100%, 99%, 87%, 44% and 23% respectively. In patients with acute pancreatitis and mumps the amylase was 84% and 83% thermolabile during the acute phase. On resolution of the pancreatitis this dropped towards normal. Patients with a pancreatic pseudocyst showed a high mean percentage thermolability (82%). These results could suggest that a component of amylase in human serum is not of pancreatic or salivary origin. In addition, this simple technique may be helpful in the diagnosis of pancreatic pseudocyst.     

Flow-injection spectrophotometric determination of diclofenac sodium in pharmaceuticals and urine samples

The localization of two salmon-type gonadotropin-releasing hormone (sGnRH) precursors, pro-sGnRH-I (short type) and pro-sGnRH-II (long type), was investigated by using in situ hybridization techniques in the brain of the landlocked sockeye salmon, Oncorhynchus nerka. We used 30-mer oligonucleotide probes complementary to pro-sGnRH-I and pro-sGnRH-II cDNA. No significant differences were observed in the localization of sGnRH neurons expressing pro-sGnRH-I and pro-sGnRH-II mRNAs; both were expressed in the olfactory nerve, the olfactory bulbs, the regions between the olfactory bulb and telencephalon, the ventral telencephalon, the preoptic area, and the hypothalamus. Almost all sGnRH neurons examined co-expressed both precursors. The expression of two sGnRH precursors in the same neuron and the wide distribution of such neurons in the brain suggest that there are no functional differences between the two precursors.     

Removal of contaminating substances before gas-liquid-chromatographic determination of aldosterone in urine

This paper deals with removal of contaminants before gas-chromatographic determination of aldosterone in urine. Urine is incubated with beta-glucuronidase, which hydrolyzes all beta-glucuronides except aldosterone-18-glucuronide. The contaminants (the aglycones released and other methylene chloride-soluble substances) are extracted with methylene chloride. Solvolysis of the aqueous phase liberates aldosterone from aldosterone-18-glucuronide, which then is extracted with methylene chloride and oxidized by use of periodic acid. The resulting lactone can be easily separated by one-dimensional thin-layer chromatography and determined by gas-liquid chromatography.     

Headspace gas chromatography with capillary column for urine alcohol determination

A headspace gas chromatographic method using a fused-silica capillary column Poraplot Q has been developed and validated for the detection and quantification of ethanol in urine. Under optimized conditions, ethanol was properly separated from acetaldehyde, acetone, isopropanol, methanol and n-propanol. Limits of detection (LODs) and quantification (LOQs) were 0.008 and 0.010 g/l, respectively. The precision studies within-run and between-run, using spiked urine samples (0.08, 0.8 and 2.0 g/l) showed maximum coefficients of variation 5.9 and 6.5%, respectively. Results of ethanol recovery varied from 91.6+/-0.8 to 103.3+/-1.8% over the concentration range from 0.01 to 3.20 g/l. The method was appropriate for the detection of ethanol in urine samples. This matrix can be used for monitoring alcohol abuse in the workplace and used in alcohol rehabilitation programs.     

Direct determination of ephedrine and norephedrine in human urine by capillary zone electrophoresis

This paper describes a simple and fast method for the simultaneous determination of ephedrine and norephedrine in urine by capillary zone electrophoresis. Separation and determination of these stimulants in human urine was performed in 50 mM phosphate buffer at pH 9.5, modifying the electroosmotic flow with acetonitrile. The method allows direct determination of the stimulants in urine in concentrations lower than 20.0 micrograms/ml, and has a limit of determination of 2.6 +/- 0.2 micrograms/ml for ephedrine and 2.3 +/- 0.2 micrograms/ml for norephedrine in urine and may be applied for doping control.     

Rapid determination of amphotericin B in serum and urine by third-order derivative spectrophotometry

A derivative spectrophotometric method for rapid monitoring of amphotericin B in serum and urine down to 30 ng/mliters is described. Samples are treated with acetonitrile, and amphotericin B is directly quantified in the crude extracts on the basis of the intensity of the peak that appears at 402 nm when the normal absorption spectrum is submitted to third-order derivative processing. Accuracy data suggested recoveries in the range of 84.3-94.9% for serum and 85.6-93.4% for urine. The precision of the method was better than 11.3% for serum and 9.2% for urine when samples contained as low as 29.6 ng/mliters of amphotericin B. Ease of applicability, short analysis time, low cost, and reliability are the main advantages of the method.     

Gas chromatographic determination of pemoline as 5-phenyl-2,4-oxazolidinedione in human urine

A simple gas chromatographic assay of the psychostimulant pemoline in human urine has been developed. Instead of extraction of the drug from urine, it is hydrolysed to 5-phenyl-2,4-oxazolidinedione with 1 N hydrochloric acid. After the extraction, this compound is methylated with diazomethane and determined by gas-liquid chromatography using a nitrogen-selective detector and a solid injection system. The method has been applied in preliminary human pharmacokinetic studies, by measuring the urinary excretion rate of pemoline following oral administration. At present, the screening procedures for doping control do not involve the detection of pemoline, but the method described can easily be incorporated in such procedures.     

Differential-pulse voltammetric determination of clenbuterol in bovine urine using a Nafion-modified carbon paste electrode

A method has been developed for the determination of clenbuterol in bovine urine using differential-pulse voltammetry (DPV), based on the electrochemical behaviour of clenbuterol at a Nafion-modified carbon paste electrode (CPE). Clenbuterol is irreversibly oxidized at high positive potentials, its irreversibility being due to a chemical follow-up reaction which results in a product showing quasi-reversible electrochemical behaviour at much lower potentials. It is the oxidation peak of this product, arising in acidic media at 0.42 V, which was analysed using DPV, again following the accumulation of clenbuterol at the Nafion-modified CPE. Electrode renewal was achieved by holding the potential at -0.6 V for 120 s in 0.1 mol l-1 NaOH. The determination of clenbuterol in the presence of interfering compounds present in bovine urine samples was then carried out after a two-step clean-up of the urine involving liquid-liquid extraction followed by a mixed-mode solid-phase extraction procedure. This allowed clenbuterol to be detected down to a level of 1.02 x 10(-9) mol l-1 in bovine urine extracts.     

Chromatographic determination of volatile solvents and their metabolites in urine for monitoring occupational exposure

The determination of volatile solvents and their metabolites in biological materials such as expired air, blood or urine allows the estimation of the degree of exposure of these chemicals. Chromatographic methods are now universally employed for this purpose and numerous analytical procedures are available for the determination of the most commonly used volatile solvents and their metabolites in urine. GC methods appear well adapted to the determination of the parent volatile solvents in blood and urine and may be used for the determination of their urinary metabolites, but these methods often require several prechromatographic steps. However, HPLC is becoming a powerful tool for the accurate and easy determination of urinary metabolites of volatile solvents, considering its decisive advantages for routine monitoring. Further, recent developments in HPLC could widen the usefulness of this method for most complex analytical problems that could be encountered during this measurement. However, despite the relative neglect of planar chromatography in this area of concern and considering the great interest in methods that could permit the simultaneous assay of numerous samples often required by routine monitoring, new approach using improved methods such as overpressured TLC could be very fruitful in the future.     

Rapid alcohol determination in plasma and urine by column liquid chromatography with biosensor detection

An enzyme based amperometric biosensor used as a selective and sensitive detection unit in column liquid chromatography for the determination of ethanol and methanol in biological fluids such as plasma and urine is described. The reagentless enzyme electrode is based on the co-immobilisation of alcohol oxidase and horseradish peroxidase in carbon paste. The selectivity of the biosensor was found to vary when four various alcohol oxidase enzyme preparations from Candida boidinii, Pichia pastoris, and Hansenula polymorpha were used in the biosensors described. High sensitivity could be obtained for a number of alcohols, organic acids, and aldehydes. Optimisation regarding the sensitivity and selectivity of the four alcohol oxidase co-immobilised biosensors are outlined. A fast and reliable liquid chromatographic separation system with a PLRP-S polymer based separation column used with a phosphate buffer as the mobile phase was optimised using the best biosensor which was based on alcohol oxidase from P. pastoris and which showed the highest turnover rate for alcohols, as the detector for the determination of ethanol and methanol in human urine and plasma samples. The selectivity and stability of the biosensor were retained by working at an applied potential of -50 mV versus Ag/AgCl, the optimal operational potential, and by the casting of a protective membrane on the electrode surface. High selectivity of the enzyme electrode was also found towards other easily oxidisable interfering species normally present in biological fluids. It was found that stable and reliable determinations of ethanol and methanol in plasma and urine could be performed with only a simple dilution and centrifugation step prior to injection into the liquid chromatographic system. An analysis time of 4 min was required for the assay, with a sample throughput of 13 samples h(-1).