Purge and trap flame photometric gas chromatography technique for the speciation of trace organotin and organosulfur compounds in a human urine standard reference material (SRM)

Ultratrace levels of organotin species and an organosulfur compound were detected in a National Bureau of Standards (NBS) human urine Standard Reference Material, SRM 2670, and a previously certified urine SRM 2672, using a purge and trap system coupled to a gas chromatograph equipped with a flame photometric detector. samples of the SRM were treated with sodium borohydride to form volatile tin hydrides. Species detected included dimethyltin (1.04 ng/ml), butyltin (0.03 ng/ml), and dimethyl-disulfide (2.73 ng/ml) in the new stock of freeze dried human urine SRM 2670 being prepared for issue by NBS and methyltin (1.0 ng/ml), butyltin (1.5 ng/ml), and inorganic tin (28.1 ng/ml) in the old stock of SRM 2672. This analytical technique should have useful applications in studies that are needed to develop a toxicological data base and monitoring programs for human organotin exposure.     

Simultaneous determination of centbutindole and its hydroxy metabolite in serum by high-performance liquid chromatography.

A high-performance liquid chromatographic assay has been developed and validated for the determination of centbutindole and its hydroxy metabolite in serum. The method involves extraction of serum samples with diethyl ether at pH greater than 8, back-extraction into 0.5 M hydrochloric acid and finally again with diethyl ether after addition of 2 M potassium hydroxide. Separation was accomplished by reversed-phase high-performance liquid chromatography on a cyano column with an acetonitrile-phosphate buffer system. The recovery of centbutindole and its metabolite was always greater than 80%. Calibration curves were linear over the concentration range 0.25-5 ng/ml for centbutindole and 0.05-1 ng/ml for the hydroxy metabolite. Although the lower limit of detection was 0.1 ng/ml for centbuntindole and 0.02 ng/ml for the hydroxy metabolite, the reliable limits of quantitation were 0.25 and 0.05 ng/ml, respectively, using 4 ml of serum.     

Determination of cetirizine in serum using reversed-phase high-performance liquid chromatography with ultraviolet spectrophotometric detection.

A method using reversed-phase high-performance liquid chromatography with ultraviolet detection for the determination of ceterizine in serum is described. The method is sensitive down to 50 ng/ml (250-microliter loop). Sample preparation involves only serum deproteination with perchloric acid and injection of the centrifuged supernatant. Elution is at pH 2.5 with acetonitrile-methanol-0.05 M phosphate buffer (33:9:58, v/v) on a 25 cm x 4.6 mm I.D. Spherisorb S5 ODS2 column. Detection is at 211 nm, its lambda max. For levels above 300 ng/ml the serum sample size is 100 microliter and a 200-microliter sample is necessary for concentrations less than 300 ng/ml. At the 2 micrograms/ml concentration the intra-assay relative standard deviation is better than 2.2%, whilst the inter-assay deviation is 2.6% over eight samples. At 200 ng/ml the intra-assay relative standard deviation is 6% over seven samples. Detector response is linear from 100 ng/ml to 10 micrograms/ml (100-microliter loop).     

Rapid method for accurate analysis of melatonin, serotonin and auxin in plant samples using liquid chromatography-tandem mass spectrometry

Currently, the information available on the physiological functions of melatonin in higher plants is rather limited and the role of plant melatonin in human health remains undetermined. Research in this area has been slow due to lack of efficient analytical methods for rapid identification and quantification of the melatonin and related compounds in complex plant matrices. In this communication, we report the development of a rapid, accurate method for extraction, detection and quantification of plant melatonin, serotonin and indole-3-acetic acid (IAA) by Liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI), respectively. The limit of detection (LOD) of melatonin in the plant extraction was 5 pg/ml and the limit of quantification (LOQ) was 0.02 ng/ml, as well as LOD for serotonin was 100 pg/ml and the LOQ was 5 ng/ml, LOD for IAA was 50 pg/ml and the LOQ was 0.7 ng/ml. There was a linear relationship between melatonin, serotonin, and IAA concentration and peak area over a quantifiable range of 0.02 ng/ml to 0.1 mg/ml, 5 ng/ml to 0.1 mg/ml, and 0.7 ng/ml to 0.1 mg/ml, respectively, in the plant extract.     

High Performance Liquid Chromatoraphic Determination of R-831, A New Antiallergic Agent,in Dogs and Humans

Abstract

A simple, selective and sensitive HPLC method has been developed to measure R-831 levels in dogs and humans. It is an internal standard technique with a single step extraction and one wash. Samples are chromatographed on a reversed-phase system with ultraviolet detection. The lowest detectable concentration for plasma is 25 ng R-831/ml with a 1 ml sample and the linear range is 25–8000 ng R-831/ml. The lowest detectable concentration for urine is 250 ng R-831/ml with a 0.1 ml sample and the linear range is 250–8000 ng R-831/ml. This method has been used to quantitate levels of R-831 in bioavailability and toxicity studies in dogs, and in pharmacokinetic and efficacy studies in humans.     

Multi-residue screening of bovine urine on xenobiotic oestrogens with an oestrogen radioreceptor assay

An improved radioreceptor assay (RRA) is used for the screening of urine samples from cattle for the presence of exogenous oestrogenic anabolic compounds, e.g., stilbenes and zeranol. The method includes extraction of the hormones from urine samples with simultaneous purification using reversed-phase C18 cartridges. High-performance liquid chromatography is used to isolate the anabolics from the naturally occurring oestrogens. Fractions containing the stilbenes and zeranol are collected and subsequently analysed using the RRA with the oestrogen receptor, isolated from immature calf uteri, as a binder and tritiated 17 beta-oestradiol as a tracer. Urine samples from untreated calves and cows and samples from calves treated with zeranol-trenbolon acetate, dienoestrol or hexoestrol or samples containing diethylstilboestrol were analysed with this RRA method. Sensitivity, specificity and predictive values were calculated at different classification levels (0.4, 0.5, 0.6 and 1.0 ng/ml 'apparent' oestradiol in urine). An optimum sensitivity (89%) with a maximum specificity (95%) was reached at a classification level of 0.6 ng/ml. At this level the detection limits in urine samples are 0.5 ng/ml for hexoestrol, 0.6 ng/ml for diethylstilboestrol, 0.9 ng/ml for dienoestrol and 5.0 ng/ml for zeranol.     

Simultaneous determination of Delta9-tetrahydrocannabinol, 11-hydroxy-Delta9-tetrahydrocannabinol and 11-nor-9-carboxy- Delta9-tetrahydrocannabinol in human plasma by high-performance liquid chromatography/tandem mass spectrometry

A rapid and sensitive method for the simultaneous confirmatory analysis of three forensic most relevant cannabinoids, Delta(9)-tetrahydrocannabinol (THC), 11-hydroxy-Delta(9)-tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH), by means of high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) in human plasma was developed and fully validated. Sample clean-up was performed by automated silica-based solid-phase extraction and the separation was carried out using a PhenylHexyl column (50 x 2 mm i.d., 3 micro m) and acetonitrile-5 mM ammonium acetate gradient elution. Data were acquired with an API 3000 LC/MS/MS system equipped with a turboionspray interface and triple quadrupole mass analyzer using positive electrospray ionization and multiple reaction monitoring. Two MS/MS transitions for each substance were monitored and deuterated analogues of analytes were used as internal standards for quantitation. The limit of quantitation was 0.8 ng ml(-1) for THC, 0.8 ng ml(-1) for 11-OH-THC and 4.3 ng ml(-1) for THC-COOH and linearity with a correlation coefficient r(2) = 0.999 was achieved up to 100 ng ml(-1) for THC and 11-OH-THC and 500 ng ml(-1) for THC-COOH. The limits of detection were 0.2 ng ml(-1) for THC, 0.2 ng ml(-1) for 11-OH-THC and 1.6 ng ml(-1) for THC-COOH. The developed LC/MS/MS method was also successfully used for the determination of THC-COOH-glucuronide, the phase II metabolite of THC-COOH.     

Simultaneous quantitation of buspirone and 1-(2-pyrimidinyl)piperazine in human plasma and urine by capillary gas chromatography-mass spectrometry

Buspirone and a buspirone metabolite, 1-(2-pyrimidinyl)piperazine (1-PP), are extracted from matrix using C18 extraction columns. The metabolite and its internal standard (d4-1-PP) are derivatized with pentafluorobenzoyl chloride to the corresponding amides. The 1-PP derivatives, buspirone and the buspirone internal standard (5-fluorobuspirone) are co-chromatographed. Chromatography and detection are performed using capillary gas chromatography with a fused-silica column and selected-ion monitoring-mass spectrometry. Linear range of the standard curves in plasma is 0.1-14 ng/ml for buspirone and 0.2-25 ng/ml for 1-PP with lower limits of quantitation of 0.1 and 0.2 ng/ml, respectively. In urine the linear range of the standard curves is 0.2-14 ng/ml for buspirone and 8-500 ng/ml for 1-PP with lower limits of quantitation of 0.2 and 8.0 ng/ml, respectively. Intra-assay accuracies were within 14% for buspirone and 1-PP in plasma and urine. Intra-assay precision was within 12% for both compounds in both matrices.     

Direct spectrophotometric determination of Nd in mixed rare earths with semi-xylenol orange and cetylpyridinium chloride

The derivative absorption spectra of the neodymium complex with Semi-Xylenol Orange and cetylpyridinium chloride has been investigated. The characteristic absorption of the complex is approximately 350 times that of neodymium chloride. The fourth-order derivative spectrum has been used to eliminate the interference of the other lanthanides, and to increase the sensitivity by a further factor of 6. Beer's law is obeyed for 0-7.5 microg of Nd in 25 ml of solution. The relative standard deviation for 7 determinations of 1.8 microg/25 ml neodymium was 1.3%. The detection limits were 5.8 ng/ml in the absence of lanthanum and 11.2 ng/ml in the presence of 44 ng/ml lanthanum (or 36 ng/ml yttrium). The method has been used for the determination of neodymium in mixed rare earths, with satisfactory results.     

Determination of piperazine in working atmosphere and in human urine using derivatization and capillary gas chromatography with nitrogen- and mass-selective detection

A reliable routine method is presented for the determination of piperazine down to the sub-ppm level in aqueous solutions and in urine. The method includes a two-phase derivatization procedure with ethyl- or isobutyl chloroformate as the reagent, followed by a capillary gas chromatographic determination using nitrogen- or mass selective detection. The addition of ammonia ensured a quantitative recovery. Detection limits for piperazine in urine were ca. 20 ng/ml using nitrogen-selective and ca. 1 ng/ml with mass-selective detection. The calibration plots were linear in the investigated range, 100-10,000 ng/ml with nitrogen-selective and 30-3000 ng/ml with mass-selective detection. The precision was ca. 6% at a concentration of 300 ng/ml. Acid anhydrides were investigated as alternative reagents in the two-phase derivatization procedure, and heptafluorobutyric acid anhydride in aqueous solutions gave approximately 100% recovery. However, in urine the recoveries of the investigated acid anhydride derivatives were unsatisfactory.     

Hydride generation atomic absorption spectrometry with insitu graphite tube trapping for the determination of Se (IV) and Se (VI) in baltic sea water samples

This paper reports the results of an optimisation study for a procedure to determine the total selenium and its inorganic species, Se(IV) and Se(VI) using atomic absorption spectrometry combined with hydride generation and in-situ trapping of the analyte on the inner walls of the graphite tube. With the use of the proposed modification, a detection limit (3σ) of 0.018 ng/ml is achieved. This paper presents exemplary results, according to the proposed procedure, for selenium determination in samples of marine water. The concentrations of selenium in the samples ranged from <0.02 ng/ml to 0.16ng/ml of Se(IV) and from <0.02 ng/ml to 0.10 ng/ml of Se(VI).     

流动注射-阴离子交换预浓集-电感耦合等离子体发射光谱法检测痕量元素——砷、硒、钼、硫、铬

本文研究了阴离子交换树脂D296对待测元素As、Se、Mo、S、Cr的预浓集性能,并与改进的流动注射(FI)(双流路)相结合,建立了一套新型、高效的FI-阴离子交换-ICP-AES分析体系。从而极大地提高了分析的频率和灵敏度,分析速度可达每小时14个样品。As、Se、Mo、S、Cr各元素的检测限分别为13.0 ng/ml、25.2 ng/ml、2.04 ng/ml、6.19 ng/ml、3.64ng/ml。利用此体系检测了标准土壤、头发、牛肝粉等,结果与标准值均很接近。     

Determination of nucleic acids using calcein-neodymium complex as a fluorescence probe.

A novel fluorometric method has been developed for rapid determination of DNA and RNA with calcein-neodymium complex as a fluorescence probe. The method is based on the fluorescence enhancement of calcein-Nd(III) complex in the presence of DNA or RNA, with maximum excitation and emission wavelength at 489 nm and 514 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.5 - 3.0 microg/ml for both DNA and yeast RNA, 0.4 - 2.0 microg/ml for fish sperm DNA (FS DNA) and 0 - 3.0 microg/ml for calf thymus DNA (CT DNA). The corresponding detection limits are 15.1 ng/ml for DNA, 21.2 ng/ml for yeast RNA, 10.5 ng/ml for FS DNA and 8.9 ng/ml for CT DNA. The interaction mechanism for the binding of calcein-Nd(III) complex to DNA is also studied. The results of absorption spectra, fluorescence polarization measurements and thermal denaturation experiments, suggested that the interaction between calcein-Nd(III) complex and DNA is an electrostatic interaction.     

Determination of dioxopiperazine metabolites of quinapril in biological fluids by gas chromatography-mass spectrometry.

The dioxopiperazine metabolites of quinapril in plasma and urine were extracted with hexane-dichloroethane (1:1) under acidic conditions. Following derivatization with pentafluorobenzyl bromide and purification of the desired reaction products using a column packed with silica gel, the metabolites were analysed separately by capillary column gas chromatography-electron-impact mass spectrometry with selected-ion monitoring. The limits of quantitation for the metabolites were 0.2 ng/ml in plasma and 1 ng/ml in urine. The limits of detection were 0.1 ng/ml in plasma and 0.5 ng/ml in urine, at a single-to-noise ratio of greater than 3 and greater than 5, respectively. The proposed method is applicable to pharmacokinetic studies.     

Simplified determining procedure for routine residue monitoring of sulphamethazine and sulphadimethoxine in milk

A simplified determining/identifying method for residual sulphamethazine (SMZ) and sulphadimethoxine (SDM) in milk by using a high-performance liquid chromatography (HPLC) with a photo-diode array detector was presented. Both sulphonamides in cow's milk samples were extracted by only stirring with ethanol followed by an Ultrafree-MC/Biomax as a centrifugal ultra-filtration unit. For determination/identification of SMZ and SDM, a Mightysil RP-18 GP Aqua column and a mobile phase of 25% (v/v) ethanol solution (in water) with a photo-diode array detector was used. Average recoveries from spiked SMZ and SDM (10-1000 ng/ml each drug) were > or = 83% with the relative standard deviations between 1.4 and 3.7%. The limit of quantitation (LOQ) were calculated to be 5 ng/ml for SMZ and 10 ng/ml for SDM, respectively. The values were below the MRL/tolerance (SMZ, 25 ng/ml; SDM, 10 ng/ml). The total time and solvent required for the analysis of one sample were <35 min and <2 ml of only ethanol, respectively. No toxic solvents were used. The developed procedure was harmless to the human and environment.     

Sensitive determination of josamycin and rokitamycin in plasma by high-performance liquid chromatography with fluorescence detection.

Rokitamycin and josamycin were successfully derivatized with dansylhydrazine in 20 min at 60 degrees C. Rokitamycin and josamycin levels were determined in plasma after ion-pair extraction into hexane-isoamyl alcohol with lauryl sulphate and precolumn derivatization. Resolution was obtained by liquid chromatography with fluorescence detection (352/537 nm) in 12 min. The limit of detection was 20 ng/ml macrolide starting from 1 ml of plasma, and linearity was demonstrated between 50 and 400 ng/ml. Inter-run coefficients of variation were 10.2% at 100 ng/ml and 9.1% at 300 ng/ml. The system was reliably used for pharmacokinetic studies in plasma.     

Determination of temazepam and temazepam glucuronide by reversed-phase high-performance liquid chromatography.

A rapid and sensitive method for extracting temazepam from human serum and urine is presented. Free temazepam is extracted from plasma and urine samples using n-butyl chloride with nitrazepam as the internal standard. Temazepam glucuronide is analyzed as free temazepam after incubating extracts with beta-glucuronidase. Separation is achieved using a C8 reversed-phase column with a methanol-water-phosphate buffer mobile phase. An ultraviolet detector operated at 230 nm is used and a linear response is observed from 20 ng/ml to 10 micrograms/ml. The limit of detection is 15.5 ng/ml and the limit of quantitation is 46.5 ng/ml. Coefficients of variation are less than 10% for concentrations greater than 50 ng/ml. Application of the methodology is demonstrated in a pharmacokinetic study using eight healthy male subjects.     

Simultaneous determination of carbaryl and azinphos-methyl in water by first-derivative synchronous spectrofluorimetry

A method is proposed for the simultaneous determination of the pesticides carbaryl (CBL) and azinphos-methyl (AZM) in water by first-derivative synchronous spectrofluorimetry. It is based on the alkaline hydrolysis of both pesticides to their metabolites 1-naphthol (from CBL) and anthranilic acid (from AZM). The constant wavelength difference chosen to optimize the determination is Δλ=λ_em?λ_ex=103 nm. CBL is measured at 302/405 nm and AZM at 333/436 nm. The calibration graphs are linear between 2.0 and 500.0 ng/ml for CBL and between 1.2 and 500.0 ng/ml for AZM with detection limits of 0.62 ng/ml and 0.35 ng/ml, respectively. The precision of the method (RSD) is 2.4% at the 80.0 ng/ml level for CBL and 2.5% at the 80.0 ng/ml level for AZM. The method is applied to the determination of both analytes in samples of natural waters.     

Direct determination of benzamides in serum by column-switching high-performance liquid chromatography.

A column-switching high-performance liquid chromatographic method with fluorescence detection was developed for the simultaneous determination of four benzamide-type anti-psychotic drugs: sulpiride, tiapride, sultopride and metoclopramide in human serum. In this method, a TSKgel Super-ODS column was used as an analytical column, and a TSKgel G 2000SW was prepared as a pretreatment column. Under the optimized analytical conditions, four benzamide-type anti-psychotic drugs were eluted within 18 min. The detection limits (S/N = 3) for sulpiride, tiapride, sultopride and metoclopramide are 1 ng/ml, 4 ng/ml, 2 ng/ml and 0.5 ng/ml, respectively. Finally, the method was applied to the determination of sulpiride in human serum samples obtained after a single oral dose of sulpiride.     

电位溶出法同时测定水质和生物样品中的铜、铅、镉、锌、铁、锰

本文提出了在乙二胺和乙二胺-盐酸体系中以计时电位溶出法测定Fe、Mn及以电位溶出法测定Cu、Pb、Cd、Zn的新方法。各元素的浓度在Fe 0.1～2600 ng/ml、Mn0.05～3200 ng/ml、Cu0.2～2800 ng/ml、Pb0.1～3600ng/ml、Cd 0.05～1200 ng/ml、Zn0.2～4200ng/ml时,浓度与溶出峰高呈良好的线性关系。本方法应用于水质及生物样品中上述各元素的测定,结果良好。