Determination of cyanide and volatile alkylnitriles in whole blood by headspace solid-phase microextraction and gas chromatography with nitrogen phosphorus detection

Simultaneous determination of cyanide and volatile alkylnitriles such as acetonitrile, cis- and trans-crotononitrile, allylnitrile and butyronitrile at low ppb concentration on whole blood (rat and mice) by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography (GC) with nitrogen phosphorus detection has been achieved for the first time. SPME extraction time and temperature were optimized using a star experimental design. Optimum conditions for cyanide extraction were chosen to analyze unspiked blood samples containing alkylnitriles as that analyte occurs at the lowest concentrations. For all analytes, the developed methodology yielded good quality parameters. In all cases, good reproducibility (relative standard deviation < or =12%), detection limits (<3ng mL(-1)) and quantification limits (<4 ng mL(-1)) were recorded.     

Fishing for a drug: solid-phase microextraction for the assay of clozapine in human plasma

Solid-phase microextraction (SPME) was investigated as a sample preparation method for assaying the neuroleptic drug clozapine in human plasma. A mixture of human plasma, water, loxapine (as internal standard) and aqueous NaOH was extracted with a 100-μm polydimethylsiloxane (PDMS) fiber (Supelco). Desorption of the fiber was performed in the injection port of a gas chromatograph at 260°C (HP 5890; 30 m×0.53 mm I.D., 1 μm film capillary; nitrogen–phosphorous selective detection). Fibers were used repeatedly in up to about 75 analyses. The recovery was found to be 3% for clozapine from plasma after 30 min of extraction. However, in spite of the low recovery, the analyte was well separated and the calibration was linear between 100 and 1000 ng/ml. The within-day and between-day precision was consistently about 8 to 15% at concentrations of 200 ng/ml to 1000 ng/ml. No interfering drug was found. The limit of detection was 30 ng/ml. The sample volume was 250 μl. The influence of the concentration of proteins, triglycerides and salt, i.e., changes in the matrix on the peak areas and peak-area ratios was studied. The method is not impaired by physiological changes in the composition of the matrix. Good agreement was found with a liquid–liquid extraction–gas–liquid chromatography (LLE–GLC) standard method and an on-line column-switching high-performance liquid chromatography (HPLC) method for patients’ samples and spiked samples, respectively. It is concluded that the method can be used in the therapeutic drug monitoring of clozapine because the therapeutic window of clozapine is from 350 to 600 ng/ml.     

HPLC method for the determination of carboplatin and paclitaxel with cremophorEL in an amphiphilic polymer matrix

Simple and rapid reversed phase HPLC methods for individual as well as simultaneous analysis of paclitaxel and carboplatin with cremophorEL (CrEL) in an amphiphilic polymer matrix were developed. Different analytical performance parameters such as linearity, accuracy, precision, specificity, limit of detection (LOD) and limit of quantification (LOQ) were determined according to ICH guidelines. All the analytical methods were developed by reverse phase HPLC on C-18 column with a mobile phase comprising of water-acetonitrile run on isocratic mode for the analysis of carboplatin and gradient mode for individual analysis of paclitaxel and for simultaneous analysis of the two drugs at a flow rate of 1 ml/min at 227 nm. The proposed methods for independent analysis of the drugs elute out carboplatin in 4.3 min and paclitaxel in 10.5 min while in simultaneous analysis carboplatin shows R(t) at 4 min and paclitaxel at 18 min with a continuous run for 17 more minutes to elute out CrEL. These methods were found to be specific as none of the components of the media, i.e. polymer, CrEL and buffer interfered with the drug peaks. The linearity of the calibration curves for each analyte in the desired concentration range was found to be good (r(2)>0.9995). The methods were accurate and precise with recoveries ranging from 98 to 101% for each drug and relative standard deviation (%RSD) <2%. Peaks corresponding to each of the drug showed positive value for the minimum peak purity index over the entire range of integrated chromatographic peak thus indicating the purity of the peaks. Stability analysis of the two drugs revealed that the drugs remain stable during the period of study.     

新疆雪莲的高效液相指纹图谱及液-质联用分析

建立新疆雪莲药材的高效液相指纹图谱。以Luna C18为分析柱,用乙腈-0.1%醋酸梯度洗脱,获得分离度较好的新疆雪莲药材HPLC分析条件。通过10批样品的分析和对照,标示出12个共有峰,相似度分析大于0.92。最后通过HPLC-UV-MS/MS联用分析鉴定出其中7个化学成分。该方法可为新疆雪莲药材指纹图谱和质量分析方法的建立提供参考。     

Is a "color effect" demonstrated for hair analysis of carbamazepine?

Psillakis et al. have reported on the concentration of carbamazepine recovered from hair samples collected from patients receiving this anti-seizure medication under medical supervision and determined that their was a high correlation between dose and quantitation of recovered analyte. The analyte was identified by two techniques, FPIA (Abbott TDx) and HPLC and the correlation was high for both procedures. In the literature on hair analysis some have suggested that analyte concentration in hair is critically dependent on hair color. In reporting their data Psillakis et al. reported the hair color of each patient but made no attempt to analyze their results in relation to color. This article performs a secondary analysis of the Psillakis et al. data in order to determine whether there is a hair color effect discernible in the recovery of carbamazepine from hair. Analysis of this data set for both the FPIA and HPLC by one-way analysis of variance fails to identify a color effect at p = .05. Weighting the data for per-patient dosage values fails to discern a color effect. Examination of all possible two-color comparisons also fails to identify a statistically significant effect for any subset of combinations. These data suggest that carbamazepine does not exhibit a color effect when using either FPIA or HPLC assay methods.     

Application of solid-phase microextraction and gas chromatography–mass spectrometry for measuring chemicals in saliva of synthetic leather workers

Saliva is of interest as a diagnostic aid for oral and systemic diseases, to monitor therapeutic drugs, and detect illicit drug abuse. It is also attractive for biological monitoring of exposure to hazardous solvents. The major advantage of this indicator over other biological monitoring targets is that the saliva is noninvasive and less confidential in comparison with blood and urine. Salivary analysis is generally acceptable by study subjects and can be applied to investigation of a wide variety of compounds. However, very few studies have been conducted on the saliva matrix to monitor exposure to hazardous solvents. The aim of this study is to establish an analytical method, headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC–MS), by which the saliva matrix can be monitored for multiple compounds with various polarities, such as methyl ethyl ketone (MEK), isopropyl alcohol (IPA), and N,N-dimethyl formamide (DMF) (common solvents used in synthetic leather manufacture), as well as acetone (ACE) and N-methyl formamide (NMF) (metabolites of IPA and DMF, respectively). We studied this technique as an alternative biological monitoring method for investigating exposure to hazardous solvents. A Carboxen/Polydimethylsiloxane (CAR/PDMS 75 μm) fiber coating was employed for this study, and various extraction and desorption parameters were evaluated. The extraction efficiency and reproducibility of analyses was improved by pre-incubation. The limits of detection were 0.004, 0.003, 0.006, 0.05, and 0.10 μg/mL for ACE, MEK, IPA, DMF, and NMF, respectively. Method validation was performed on standards spiked in blank saliva, and a correlation was made between HS-SPME and traditional solvent pretreatment methods. It was found that correlation coefficients (r) were greater than 0.996 for each analyte, with no significant differences (p > 0.05) between two methods. However, the SPME method achieved lower limits of detection, with good accuracy (recovery 95.3–109.2%) and precision (1.17–8.22% CV) for both intra- and inter-assay, when quality control samples were analyzed for all five compounds. The partition coefficient for each compound between the headspace of the saliva sample and the CAR/PDMS fiber coating was 90.9, 170.1, 36.4, 3.70 and 0.92 for ACE, MEK, IPA, DMF and NMF, respectively. Real sample analyses were performed on workers in a synthetic leather factory. In summary, the SPME method is a highly versatile and flexible technique for chemical measurement, and we demonstrate its application for monitoring biological exposure to hazardous solvents. Saliva monitoring using sensitive SPME approaches for determining workplace exposure should prove useful as an alternative exposure monitoring method.     

Analytical methods applied to the determination of heterocyclic aromatic amines in foods

Analytical aspects concerning the heterocyclic aromatic amines (HAAs) determination in foods are reviewed. Sample pre-treatment procedures such as liquid-liquid extraction (LLE), supercritical fluid extraction, solid-phase extraction (SPE), solid-phase microextraction (SPME), and the mainly used LLE-SPE tandem extraction are discussed. The analytical methods used for the identification and quantification are HPLC, HPLC combined with single or tandem MS detection (HPLC-MS, HPLC-MS/MS), GC-MS and capillary electrophoresis. Advantages and figures of merit for each technique are discussed.     

The influence of six pharmaceuticals on freshwater sediment microbial growth incubated at different temperatures and UV exposures

Pharmaceutical compounds have been detected in freshwater for several decades. Once they enter the aquatic ecosystem, they may be transformed abiotically (i.e., photolysis) or biotically (i.e., microbial activity). To assess the influence of pharmaceuticals on microbial growth, basal salt media amended with seven pharmaceutical treatments (acetaminophen, caffeine, carbamazepine, cotinine, ibuprofen, sulfamethoxazole, and a no pharmaceutical control) were inoculated with stream sediment. The seven pharmaceutical treatments were then placed in five different culture environments that included both temperature treatments of 4, 25, 37°C and light treatments of continuous UV-A or UV-B exposure. Microbial growth in the basal salt media was quantified as absorbance (OD(550)) at 7, 14, 21, 31, and 48d following inoculation. Microbial growth was significantly influenced by pharmaceutical treatments (P?相似文献   

Capillary liquid chromatographic analysis of fat-soluble vitamins and β-carotene in combination with in-tube solid-phase microextraction

A capillary liquid chromatography (CLC) system with UV/vis detection was coupled with an in-tube solid-phase microextraction (SPME) device for the analysis of fat-soluble vitamins and β-carotene. A monolithic silica-ODS column was used as the extraction medium. An optical-fiber flow cell with a long light path in the UV/vis detector was utilized to further enhance the detection sensitivity. In the in-tube SPME/CLC system, the pre-condition of the extraction column and the effect of the injection volume were investigated. The detection limits (LOD) for the fat-soluble vitamins and β-carotene were in the range from 1.9 to 173 ng/mL based on the signal-to-noise ratio of 3 (S/N = 3). The relative standard deviations of migration time and peak area for each analyte were less than 5.0%. The method was applied to the analysis of fat-soluble vitamins and β-carotene contents in corns.     

High-performance liquid chromatographic determination of finasteride in human plasma using direct injection with column switching

A fully automated column-switching high-performance liquid chromatographic (HPLC) method was developed for the quantification of finasteride [N-(1,1-dimethylethyl)-3-oxo-4-aza-5α-androst-1-ene-17β-carboxamide] in human plasma. Plasma samples were diluted with an equal volume of ethylene glycol-water (40:60, v/v), then the diluted sample (150 μl) was injected into the HPLC system without clean-up. The analyte was retained on a pretreatment column, whereas plasma proteins and other endogenous components were washed out to waste. The analyte was transferred to the analytical column in the heart-cut mode and then detected at 210 nm. A quantification limit of 1 ng/ml was attained. There was a linear relationship between peak height and drug concentration in plasma in the range 1–50 ng/ml. This method was validated and applied to the assay of plasma samples to characterize pharmacokinetic parameters in clinical studies.     

Characterization and application of PBA fiber optic chemical film sensor based on fluorescence multiple quenching

The three types of structure of the pyrenebutyric acid of fiber optic chemical film sensor were stud-ied by fluorescence multiple quenching. They are, for different test samples and purposes, respectively general, three-way and combined. A tri-cup method was designed to demonstrate the multiple quenching of response mechanism, and a relationship formula of mathematical approach was established. The response mechanism was shown to include the dynamic quenching , inner-filter effects and/or resonance energy transfer. To show the response characterization in a series of organic and inorganic quenchers, a new concept of apparent quenching coefficient Kq was advanced. This kind of sensor has been used in continuous and in situ monitoring of the dissolution rate of drug tablets, on line and in situ monitoring of some organic therapeutic drugs in biological fluid and Cr( VI ) in industrial waste water. The measured data were examined and compared with HPLC or HPTLCS. Test results show that the sensors and appa     

Immobilized RNA switches for the analysis of complex chemical and biological mixtures

A prototype biosensor array has been assembled from engineered RNA molecular switches that undergo ribozyme-mediated self-cleavage when triggered by specific effectors. Each type of switch is prepared with a 5'-thiotriphosphate moiety that permits immobilization on gold to form individually addressable pixels. The ribozymes comprising each pixel become active only when presented with their corresponding effector, such that each type of switch serves as a specific analyte sensor. An addressed array created with seven different RNA switches was used to report the status of targets in complex mixtures containing metal ion, enzyme cofactor, metabolite, and drug analytes. The RNA switch array also was used to determine the phenotypes of Escherichia coli strains for adenylate cyclase function by detecting naturally produced 3',5'- cyclic adenosine monophosphate (cAMP) in bacterial culture media.     

Chemical differences in volatiles between Melittis melissophyllum L. subsp. melissophyllum and subsp. albida (Guss) P. W. Ball (Lamiaceae) determined by solid-phase microextraction (SPME) coupled with GC/FID and GC/MS

Melittis melissophyllum (Lamiaceae) is a perennial herb, typical of woody places, occurring in Italy with two subspecies, i.e., melissophyllum and albida. So far, the classification of these two taxa was only based on morphology, i.e., the presence of glandular trichomes, the dimension of the leaves, and the number of teeth on each side as the main discriminant characters. To find marker compounds to chemically discriminate the subsp. melissophyllum with respect to the subsp. albida, a solid-phase microextraction SPME analysis coupled with GC/FID (=flame ionization detector) and GC/MS was carried out. SPME proved to be a chemotaxonomically useful technique that permitted a clearly differentiation of the two subspecies at headspace level. The subsp. melissophyllum was characterized by high amount of the mushroom alcohol oct-1-en-3-ol and the phenolic coumarin, whilst the subsp. albida exhibited a high content in monoterpenes and sesquiterpenes, α-pinene, sabinene, and (E)-caryophyllene being the major compounds. Multivariate chemometric techniques, such as cluster analysis (CA) and principal-component analysis (PCA), were used to support chemical data and characterize the population according to the taxonomy. In addition, the micromorphology and distribution of glandular trichomes of both subspecies were studied by scanning electron microscopy (SEM).     

Study of ligand-receptor binding using SPME: investigation of receptor, free, and total ligand concentrations

The theoretical background and practical approaches for studying ligand-receptor (protein) binding by solid phase microextraction (SPME) are investigated, along with methods for simultaneous calculation of receptor, free, and total ligand concentrations. With the introduction of new extraction phases (restricted access materials, molecularly imprinted polymers, and immobilized antibodies), SPME allows better separation of small molecules of ligand from larger molecules of receptor, and improved accuracy. This sample preparation method based on nonexhaustive extraction is well suited as a general method to study and quantify systems involving multiple equilibriums, with significant advantages over currently used methods. SPME was used previously for the determination of protein binding constants, but only with conventional extraction phases and in simple cases, with a 1:1 combination ratio between the ligand and the receptor or when negligible depletion conditions were met. The new theoretical approach presented in this study allows the quantification of any binding equilibrium, regardless of the extent of depletion. Restricted-access particles are used as extraction phase, and if the amount of receptor is limited, selected regions of the binding curve may be obtained using a single sample, with a volume as low as 10 muL. The equations developed here are simple and independent of the analytical method used for the quantification of the amount of ligand. Three different practical approaches are presented: the method of multiple standard solutions, the method of successive extractions from the same sample and the method of successive additions to the same sample. The usefulness of this novel approach is demonstrated by using it to determine the binding parameters of some selected drugs to human serum albumin. These parameters are subsequently used to calculate albumin, free drug, and total drug concentrations from unknown mixtures. The results are in good agreement with previously published data. Quantification of the amount of ligand extracted by SPME is done by liquid chromatography coupled with tandem mass spectrometry.     

Solid-phase microextraction and the human fecal VOC metabolome

The diagnostic potential and health implications of volatile organic compounds (VOCs) present in human feces has begun to receive considerable attention. Headspace solid-phase microextraction (SPME) has greatly facilitated the isolation and analysis of VOCs from human feces. Pioneering human fecal VOC metabolomic investigations have utilized a single SPME fiber type for analyte extraction and analysis. However, we hypothesized that the multifarious nature of metabolites present in human feces dictates the use of several diverse SPME fiber coatings for more comprehensive metabolomic coverage. We report here an evaluation of eight different commercially available SPME fibers, in combination with both GC-MS and GC-FID, and identify the 50/30 μm CAR-DVB-PDMS, 85 μm CAR-PDMS, 65 μm DVB-PDMS, 7 μm PDMS, and 60 μm PEG SPME fibers as a minimal set of fibers appropriate for human fecal VOC metabolomics, collectively isolating approximately 90% of the total metabolites obtained when using all eight fibers. We also evaluate the effect of extraction duration on metabolite isolation and illustrate that ex vivo enteric microbial fermentation has no effect on metabolite composition during prolonged extractions if the SPME is performed as described herein.     

The Cumulative Risk to Human Health of Pharmaceuticals in New Jersey Surface Water

Surface water in New Jersey is used by many residential drinking water facilities. Like many water sources it is contaminated by upstream industrial and residential sources, including pharmaceutical residues. This research examines the concentrations of 18 pharmaceuticals in 30 New Jersey locations, their acceptable daily exposures (ADE), and potential drug–drug interactions (DDI). The surface water data was provided by the U.S. Geological Survey (USGS). ADEs for human health were set for each pharmaceutical in the study. The pharmaceuticals were evaluated for known adverse health interactions and their potential health impact. These factors were brought together using a cumulative hazard index (HI) risk assessment calculation to assess the overall risk of pharmaceuticals in NJ surface water to human health. When examining the potential for DDI in this assessment, the risk increased but not appreciably. The HI for the sample locations ranged from <0.00001 to 0.01 with the DDI adding less than 1.2× increase to the overall risk. The calculated risk of these mixtures was also increased to an extreme DDI of 7 times per interaction. A noticeable increase in the calculated risk was seen, but in no cases did it reach a level of concern.     

Analysis of biological samples using solid-phase microextraction

Solid-phase microextraction (SPME) has gained widespread acceptance for analyte-matrix separation and preconcentration. SPME is a simple, effective adsorption/desorption technique that eliminates the need for solvents or complicated apparatus for concentrating volatile or non-volatile compounds in liquid samples or headspace. SPME is compatible with analyte separation/detection by gas chromatography and high performance liquid chromatography and provides linear results for a wide range of concentrations of analytes. By controlling the polarity and thickness of the coating on the fiber, maintaining consistent sampling time, and adjusting several other extraction parameters, an analyst can ensure highly reliable results for low concentrations of analytes. This review provides updated information on SPME with chromatographic separation for the extraction and measurement of different analytes in biological fluids and materials. Firstly the background to the technique is given in terms of apparatus, fibers used, extraction conditions and derivatisation procedures. Then the different matrices, urine, blood, breast milk, hair and saliva are considered separately. Finally, the future potential of SPME for the analysis of biological samples in terms of the development of new devices and fiber chemistries as well as applications for in vivo studies are discussed.     

Determination of radical yields in solid-state drugs as one technique to identify drugs that will withstand radiosterilization: radioresistance of beta blockers

This article describes a simple preliminary test to determine whether a drug is sufficiently radioresistant to withstand radiosterilization. The test is based on the electron spin resonance (ESR) detection of radicals produced after irradiation of a solid-state drug, assuming that these radicals are the precursors of the final products detected after dissolution of the drug. A calibration curve has therefore been established by measuring ESR spectra of l-alanine irradiated at different doses. The response factor to quantify the radicals is the normalized double integration (DI) of the whole first-derivative ESR spectrum. The curve gives the relationship between the normalized DI and the number of radicals. Eight beta blockers have been chosen and their radical yield determined. This is the first time that several different drugs of the same pharmacological group have been studied and compared. The results obtained are similar for seven of the eight beta blockers; the mean G value (excepted for nadolol) is 3 x 10(-9) mol/J. This means that beta blockers are radioresistant. The two most radiosensitive drugs (nadolol and esmolol hydrochloride) were also studied by high-performance liquid chromatography (HPLC). No significant loss of the active compound was detected, which confirms this radioresistant property. Moreover, no change in color or smell was observed. Using ESR and HPLC, beta blockers were identified as potential candidates for radiosterilization.     

Quantitative determination of a selective alpha-1a receptor antagonist in human plasma by high-performance liquid chromatography with tandem mass spectrometric detection

Solid-phase extraction, utilizing a 96-well plate format, was used to isolate an alpha-1a receptor antagonist and internal standard from human plasma. Following the isolation procedure, the analyte and internal standard were separated and detected using reversed-phase HPLC coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry operated in the positive ion multiple reaction monitoring (MRM) mode. Based upon the peak area ratio (analyte: internal standard) the analyte was quantified over a concentration range of 0.02-2 ng/ml. Assay validation results including parameters such as precision and accuracy are presented. The validated method was subsequently used to support human pharmacokinetic studies.