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PubMed2003

Time since discharge of shotgun shells.

A technique for the estimation of time since discharge of a given class of spent shotgun shells is presented. The technique involved the use of SPME (Solid Phase Microextraction) sampling from the atmosphere inside spent shotgun shells. Compounds absorbed on the SPME fiber were desorbed and analyzed with GC-MS. The decrease in concentration of the combustion product naphthalene was monitored in all shells over a two-month period. Three conditions were examined to prevent naphthalene from escaping prior to testing the shells. A glass vial was successfully incorporated to halt the dissipation of naphthalene. At room temperature the naphthalene peak can be measured for several months and the curve-fitting data can lead to an estimation of time since discharge.

Journal Article↗
PubMed2004

New developments in SPME Part 2: Analysis of ammonium nitrate-based explosives.

Solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) is a simple, reliable technique for the recovery and analysis of many organic explosives. However, this technique is impractical for the analysis of ammonium nitrate-type explosives due to the extreme polarity, low molecular weight, and high volatility of the amine moiety. This article describes an initial investigation of a derivatization process utilizing alkylchloroformates that converts ammonium nitrate and methylammonium nitrate into a form suitable for recovery by SPME and analysis by GC-MS.

Journal Article↗
PubMedDate not supplied

Determination of thiabendazole in orange juice and rind by liquid chromatography with fluorescence detection and confirmation by gas chromatography/mass spectrometry after extraction by matrix solid-phase dispersion.

A method was developed for the determination of thiabendazole (TBZ) in orange juice and rind based on matrix solid-phase dispersion (MSPD). TBZ was extracted with ethyl acetate and the extract was subsequently cleaned up on a solid-phase extraction column. Fungicide residues were determined by liquid chromatography with fluorescence detection. Recoveries through the method ranged from 87 to 97% with relative standard deviations < or = 11%. The detection and quantitation limits were 0.15 and 0.50 microg/kg, respectively. The confirmation of TBZ residues in positive samples was performed by solid-phase microextraction followed by gas chromatography with mass spectrometric detection using selected ion monitoring. The developed method was applied to determine TBZ levels in commercial orange juices and in juice and rind of fresh oranges. The influence of storage and washing of fruits on TBZ residues was also studied.

Beverages↗
PubMed2004

Analysis of roasted coffee bean volatiles by using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

The volatile headspace from two coffee bean varieties, namely Arabica (Coffea arabica) and Robusta (Coffea canephora ex Froehner), were sampled by using solid-phase microextraction (SPME), and then analysed with comprehensive two-dimensional gas chromatography interfaced to a time-of-flight mass spectrometer (GC x GC-TOFMS). Two distinct column set combinations were investigated--an apolar-polar and polar-apolar configuration--and the separation achieved from each set was compared. Results were compared with a previous literature report for coffee analysed by GC x GC-FID, using an analogous polar-apolar column set combination, where authentic standards were used to confirm the position of the selected components in the 2D separation space. The present study provides independent mass spectral confirmation of component identity, and demonstrates that the relative, structured position of these components is comparable in the two experiments. Total ion current (TIC) chromatograms were processed using ChromaTOF automated data processing software. It was necessary to restrict the number of processed peaks to 1000 (S/N > 100), which required approximately 8 h for processing. Extracted ion chromatograms were generated using prominent fragment ions, and unique masses, to aid in analyte identification process, and was particularly useful in instances of component peak overlap, and for the identification of pyrazine analytes (e.g. 44, 88, 122 u). Semi-quantitative analysis was restricted to the 44 selcted components; however, the omission of peaks with S/N < 100, limiting the processed peaks to 1000, reduced the semi-quantitative application of the GC x GC-TOFMS method developed. Finally, results gained from GC x GC-TOFMS and GC x GC-qMS analyses were comparable with respect to spectral similarity assignments for the 44 target analytes.

Coffee↗
PubMed2005

[Analysis and identification of Liriomyza sativae-attractants from cowpea and kidney bean volatiles].

In this paper, the volatiles from cowpea and kidney bean, the main host plants of American leafminer Liriomyza sativae, were collected and extracted by a self-designed device and solid phase microextraction (SPME) technique, and analyzed by GC-MS. The results showed that the volatiles from the two beans had the same components mainly consisted of 2-hexenal, 3-Hexen-1-ol, 2-Hexen-1-ol, 1-Octen-3-ol, 3-Hexenol acetate, alpha-Ionone and beta-Ionone. The lure made of the seven components was attractive to L. sativae in field trapping trials. Detailed analyses indicated that alpha-Ionone and beta-Ionone might play important roles in the searching behavior of L. sativae for host plants.

Animals↗
PubMedDate not supplied

Analysis of the chloroacetanilide herbicides in water using SPME with CAR/PDMS and GC/ECD.

The solid-phase microextraction (SPME) technique using a 75 mm film of carboxen/polydimethylsiloxane was applied to the analysis of chloroacetanilide herbicides (acetochlor, alachlor, butachlor, metolachlor, and propachlor) residues. The feasibility of SPME with gas chromatography electron capture detection analysis has been evaluated. The effects of experimental parameters such as magnetic stirring, salt addition, humic acid addition, pH value, and extraction time, as well as desorption temperature and time, were investigated. Analytical parameters such as linearity, repeatability and limit of detection were also evaluated. The inhibition of humic acid to the extraction of chloroacetanilide herbicides was observed. A standard addition method for calibration was recommended to reduce deviations caused by matrix interferences. The proposed method provided a simple and rapid analytical procedure for chloroacetanilide herbicides in water with limits of detection 0.002-0.065 microg/L for deionized water, and 0.005-0.22 microg/L for farm water. The relative standard deviations (n = 5) for analyses of farm water were 7-20% for 5 [corrected] microg/L chloroacetanilide herbicides. This application was illustrated by the analysis of sample collected from farm water in the Chung-hwa area, Taiwan.

Acetamides↗
PubMed2005

[Roles of olfaction and vision in orientation behavior of adult Campylomma chinensis Schuh (Hemiptera: Miridae) toward Lantana plants (Verbanaceae)].

Investigations were carried out on the orientation behavior of adult Campylomma chinensis Schuh (Hemiptera: Miridae) toward plant hosts Lantana camara, L. caniara cv. 'Flava', and L. montevidensis (Spreng. ) Briq. (Verbanaceae). Surveys on three Lantana plants showed that the distribution of C. chinensis in inflorescences was not related to floral color (partial correlation coefficient was 0.240, P = 0. 147, n = 40), but to the number of Thrips hawiiensis Morgan (partial correlation coefficient was 0.512, P < 0.0001, n = 40) and the flowers per inflorescence (partial correlation coefficient was 0.451, P < 0.0001, n = 40). In a colour preference experiment, no adult C. chinensis attracted to six different colour plates in longan field. The testing results of four-armed olfactometer indicated that adult C. chinensis had a significantly higher preference for L. camara. It was concluded that olfactory stimuli played an important role in searching for plant hosts of C. chinensis. Solid phase microextraction (SPME) and GC-MS were employed to analyze the volatiles compounds of Lantana, and seven same chemical constituents were detected from the volatiles of three Lantana plants inflorescence.

Animals↗
PubMed2005

Chromatographic analysis in bacteriologic diagnostics of blood cultures, exudates, and bronchoalveolar lavages.

This article summarizes our previously achieved and published results. The method for the determination of bacterial volatile fatty acid patterns (VFA) in clinical samples was elaborated. It employs gas chromatography (GC), solvent extraction or head-space solid phase microextraction (SPME). This method was validated by analyses of reference bacterial strains. After cultivation in defined media, aerobic and facultative anaerobic bacteria provided profiles with a low or none acid content, while anaerobic bacteria provided characteristic but medium-dependent profiles with a higher acid content. This method was used for the analyses of clinical samples of total 375 blood cultures, 205 suppurative and apyogenous exudates, and 210 bronchoalveolar lavages (BALs). These analyses enabled within 30 minutes the detection of microbes, probably non-sporulating anaerobes not found by false-negative cultivation, in 11.2% of blood cultures, in 20.0% of exudates, and in 9.0 to 20.0% of BALs. Using the mass spectrometry (MS) methods, a number of other components with unclear diagnostic importance were found in BAL samples, in particular hydrogen cyanide, methanol, ethanol, hexanol, acetone, cyclohexanone, acetonitrile, formaldehyde, acetaldehyde, ethyl acetate, and other esters. Cyclohexanone, occurring mainly in BALs of patients with pneumonia, undergoing intensive care, may originate as a residual solvent from the plastic parts of the ventilation apparatus.

Bacteria, Anaerobic↗
PubMed2005

Identification of volatile emissions from Platypus mutatus (=sulcatus) (Coleoptera: Platypodidae) and their behavioral activity.

We report here the identification and behavioral activity of volatile compounds emitted by male Platypus mutatus (=sulcatus) Chapuis while boring galleries in living poplar, Populus deltoides Marshall, trees. Headspace analysis using solid phase microextraction techniques showed the presence of 6-methyl-5-hepten-2-ol (sulcatol) and 6-methyl-5-hepten-2-one (sulcatone). Only one enantiomer of sulcatol, retusol, was found to be part of the volatile emission. Behavioral assays showed that females are more attracted than males to galleries with boring males inside. Both sulcatol and sulcatone elicited electroantennographic responses by female P. mutatus. Furthermore, behavioral bioassays showed that both sulcatol and sulcatone elicit behaviorally attractive responses by females. These results suggest that male P. mutatus releases a sex pheromone composed mainly of retusol and sulcatone.

Animals↗
PubMedDate not supplied

Determination of 1,3-dichloropropanol in soy sauce and related products by headspace gas chromatography with mass spectrometric detection: interlaboratory study.

An interlaboratory study was performed to evaluate the effectiveness of a headspace gas chromatography (GC) method for the determination of 1,3-dichloro-propan-2-ol (1,3-DCP) in soy sauce and related products at levels above 5 ng/g. The test portion is mixed with an internal standard (d5-1,3-DCP) and ammonium sulfate in a sealed headspace vial. After achieving equilibrium, the headspace is sampled either by gas-tight syringe or solid-phase microextraction (SPME) and analyzed by GC with mass spectrometric detection. 1,3-DCP is detected in the selected-ion mode (monitoring m/z 79 and 81 for 1,3-DCP and m/z 82 for the deuterated internal standard) and quantified by measurement against standards. Test materials comprising soy, dark soy, mushroom soy, and teriyaki sauces, both spiked and naturally contaminated, were sent to 9 laboratories in Europe, Japan, and the United States; of these, 5 used SPME and 4 used syringe headspace analysis. Test portions were spiked at 5.0, 10.0, 20.0, 100.0, and 500.0 ng/g. The average recovery for spiked blank samples was 108% (ranging from 96-130%). Based on results for spiked samples (blind pairs at 5, 10, 20, 100, and 500 ng/g) as well as a naturally contaminated sample (split-level pair at 27 and 29 ng/g), the relative standard deviation for repeatability (RSDr) ranged from 2.9-23.2%. The relative standard deviation for reproducibility (RSDR) ranged from 20.9-35.3%, and HorRat values of between 1.0 and 1.6 were obtained.

Calibration↗
PubMed2006

Determination of free concentration of Paclitaxel in liposome formulation.

PURPOSE: An important step in the development of liposome-based formulations is estimating the free drug concentration in the aqueous solution surrounding liposomes. This research presents a new method for determination of free concentrations, based on membrane-protected solid-phase microextraction (SPME). METHODS: For effective direct extraction of low molecular weight compounds from complex liquid samples, a hollow membrane was used to form a concentric sheath around a coated SPME fiber. The membrane blocked the access of large particles, like liposomes, to the coating surface, while target analytes with low molecular weight diffused through the membrane and reached the extraction phase. Quantification was conveniently performed by reversed-phase liquid chromatography coupled to electrospray ionization mass spectrometry. RESULTS: The carbowax/templated resin SPME fiber was determined to be the most suitable for these assays, providing enough sensitivity when an extraction time of one hour was used. The free concentration of paclitaxel was found to be 0.36 microg/mL, significantly below the solubility limit of paclitaxel in water. CONCLUSION: The method was successfully applied for determining free paclitaxel in liposome formulations based on dioleyl-trimethyl-ammonium-propane, with good linearity over the range of concentrations of interest. The method was faster and more practical than equilibrium dialysis, as the SPME approach provided preconcentration and convenient delivery to the analytical system.

Antineoplastic Agents↗
PubMed2006

[Extraction and determination of short-chain fatty acids in biological samples].

Short-chain fatty acids are organic acids with 1 - 6 carbon atoms. Their physiological functions and clinical applications have attracted considerable attention. Their high polarity, low ultraviolet (UV) absorbance, low contents in biological samples, high volatility, good water-solubility and easy adsorption on metal and glass surfaces result in some difficulties in their separation and determination. This review focuses on the methods for extraction of short-chain fatty acids in biological samples such as feces, urine, blood and culture solutions by distillation, high speed centrifugation, liquid-solid extraction, solid phase microextration, supercritical fluid extraction and liquid phase microextraction and determination by gas chromatography, high performance liquid chromatography and capillary electrophoresis. Sixty-three references are cited.

Adsorption↗
PubMed2006

A validated SPME-GC-MS method for simultaneous quantification of club drugs in human urine.

A solid-phase microextraction-gas chromatographic-mass spectrometric (SPME-GC-MS) method has been developed and validated for measuring four club drugs in human urine. These drugs include gamma-hydroxybutyrate (GHB), ketamine (KET), methamphetamine (MAMP), and methylenedioxymethamphetamine (MDMA). These drugs are referred to as 'club drugs' because of their prevalence at parties and raves. Deuterium labeled internal standards for each of the four drugs was included in the assay to aid in quantitation. The drugs were spiked into human urine and derivatized using pyridine and hexylchloroformate to make them suitable for GC-MS analysis. The SPME conditions of extraction time/temperature and desorption time/temperature were optimized to yield the highest peak area for each of the four drugs. The final SPME parameters included a 90 degrees C extraction for 20min with a 1min desorption in the GC injector at 225 degrees C using a splitless injection. All SPME work was done using a 100microm PDMS fiber by Supelco. The ratio of pyridine to hexylchloroformate for derivatization was also optimized. The GC separation was carried out on a VF-5ht column by Varian (30m, 0.25mm i.d., 0.10microm film thickness) using a temperature program of 150-270 degrees C at 10 degrees C/min. The instrument used was a ThermoFinnigan Trace GC-Polaris Q interfaced with a LEAP CombiPal autosampler. The data was collected by using extracted ion chromatograms of marker m/z values for each drug from the total ion chromatograms (TIC) (full scan mode). Calibration curves with R(2)>0.99 were generated each day using the peak area ratios (peak area drug/peak area internal standard) versus concentration. The validated method resulted in intra-day and inter-day precision (% R.S.D.) of less than 15% and a % error of less than 15% for four concentrations in the range of 0.05-20microg/mL (MAMP) and 0.10-20microg/mL (GHB, KET, and MDMA). This method has the advantage of an easy sample preparation with acceptable accuracy and precision for the simultaneous quantification of these four drugs of abuse and shows no interference from the urine matrix.

Central Nervous System Agents↗
PubMed2007

A simplified bioprocess for human alpha-fetoprotein production from inclusion bodies.

A simple and effective Escherichia coli (E. coli) bioprocess is demonstrated for the preparation of recombinant human alpha-fetoprotein (rhAFP), a pharmaceutically promising protein that has important immunomodulatory functions. The new rhAFP process employs only unit operations that are easy to scale and validate, and reduces the complexity embedded in existing inclusion body processing methods. A key requirement in the establishment of this process was the attainment of high purity rhAFP prior to protein refolding because (i) rhAFP binds easily to hydrophobic contaminants once refolded, and (ii) rhAFP aggregates during renaturation, in a contaminant- dependent way. In this work, direct protein extraction from cell suspension was coupled with a DNA precipitation-centrifugation step prior to purification using two simple chromatographic steps. Refolding was conducted using a single-step, redox-optimized dilution refolding protocol, with refolding success determined by reversed phase HPLC analysis, ELISA, and circular dichroism spectroscopy. Quantitation of DNA and protein contaminant loads after each unit operation showed that contaminant levels were reduced to levels comparable to traditional flowsheets. Protein microchemical modification due to carbamylation in this urea-based process was identified and minimized, yielding a final refolded and purified product that was significantly purified from carbamylated variants. Importantly, this work conclusively demonstrates, for the first time, that a chemical extraction process can substitute the more complex traditional inclusion body processing flowsheet, without compromising product purity and yield. This highly intensified and simplified process is expected to be of general utility for the preparation of other therapeutic candidates expressed as inclusion bodies.

Escherichia coli↗
PubMed2006

A high-throughput, fully automated liquid/liquid extraction liquid chromatography/mass spectrometry method for the quantitation of a new investigational drug ABT-869 and its metabolite A-849529 in human plasma samples.

ABT-869 is a novel ATP-competitive inhibitor for all the vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor tyrosine kinases (RTKs). It is one of the oncology drugs in development at Abbott Laboratories and has great potential for enhanced anti-tumor efficacy as well as activity in a broad range of human cancers. We report here an accurate, precise and rugged liquid chromatography/mass spectrometry (LC/MS/MS) assay for the quantitative measurement of ABT-869 and its acid metabolite A-849529. A fully automated 96-well liquid/liquid extraction method was achieved utilizing a Hamilton liquid handler. The only manual intervention required prior to LC/MS/MS injection is to transfer the 96-well plate to a drying rack to dry the extracts then transfer the plate back to the Hamilton for robotic reconstitution. The linear dynamic ranges were from 1.1 to 598.8 ng/mL for ABT-869 and from 1.1 to 605.8 ng/mL for A-849529. The coefficient of determination (r2) for all analytes was greater than 0.9995. For the drug ABT-869, the intra-assay coefficient of variance (CV) was between 0.4% and 3.7% and the inter-assay CV was between 0.9% and 2.8%. The inter-assay mean accuracy, expressed as percent of theoretical, was between 96.8% and 102.2%. For the metabolite A-849529, the intra-assay CV was between 0.5% and 5.1% and the inter-assay CV was between 0.8% and 4.9%. The inter-assay mean accuracy, expressed as percent of theoretical, was between 96.9% and 100.6%.

Blood Chemical Analysis↗
PubMed2006

Analysis of hormonal steroids in fish plasma and bile by coupling solid-phase extraction to GC/MS.

An analytical procedure for the simultaneous determination of twelve endogenous steroids (testosterone, androstenedione, 17beta-estradiol, estrone, pregnenolone, progesterone, dihydroandrostenedione, dihydrotestosterone, 11alpha-ketotestosterone, 17alpha-hydroxyprogesterone, 17alpha-hydroxypregnenolone, 17alpha,20beta-dihydroxy-4-pregnen-3-one) in plasma and bile samples by solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC-MS) has been developed. After enzymatic hydrolysis for bile samples only, samples were concentrated and purified using two successive SPE (C(18) and NH(2)) cartridges. Analytes were derivatized with a mixture of N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) / mercaptoethanol / ammonium iodide (NH(4)I) and determined by GC-MS in selective ion monitoring mode. For most of the steroids monitored, recoveries were in the range 90-120% in plasma and in the range 60-70% in bile, and the reproducibility was below 10% for the complete procedure. Limits of detection obtained ranged from 0.1 to 0.4 ng/g in fish plasma and from 1.6 to 14 ng/g in fish bile. The developed method was successfully applied to the determination of plasma steroids in flounders (Platichthys flesus) collected from two French estuaries.

Animals↗
PubMed2006

Sample treatments prior to capillary electrophoresis-mass spectrometry.

Sample preparation is a crucial part of chemical analysis and in most cases can become the bottleneck of the whole analytical process. Its adequacy is a key factor in determining the success of the analysis and, therefore, careful selection and optimization of the parameters controlling sample treatment should be carried out. This work revises the different strategies that have been developed for sample preparation prior to capillary electrophoresis-mass spectrometry (CE-MS). Namely the present work presents an exhaustive and critical revision of the different samples treatments used together with on-line CE-MS including works published from January 2000 to July 2006.

Analytic Sample Preparation Methods↗
PubMed2006

Current perspectives in analyte extraction strategies for tin and arsenic speciation.

Nowadays, reliable and robust detectors can be considered standard laboratory instrumentation, which, for most of the elements provide quantitation limits in the lower ng/g range. Despite these advances in detector technology, sample preparation is by far the most important error source in modern analytical method development and can be judged as the "Achilles' heel" of any analytical process regarding reliability of the obtained results and time consumption. The aim of the present review is to highlight modern trends for tin and arsenic speciation, as these analytes can be considered as models for challenges in modern method development in this field. First background information, legislative aspects and current needs are elucidated. Then the role of sample treatment within the process of method development in speciation is discussed, followed by a presentation of modern extraction techniques, matching the requirements for arsenic and tin speciation analysis: to provide mild conditions in order to ensure species preservation, to improve species recovery, to enhance sample throughput and to be suitable for hyphenation with chromatographic separation systems. The review includes applications on tin and arsenic speciation, covering the period of 2001-2006.

Analytic Sample Preparation Methods↗