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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method for the determination of alprenolol and its 4-hydroxy metabolite has been developed. The urine sample is made alkaline with buffer (pH 12) and derivatized with 60 microliter of 2 M phosgene in toluene with vigorous shaking. In the presence of 2.5% methanol, an oxazolidineone methyl carbonate is formed from 4-hydroxy alprenolol. The now neutral derivatives are extracted with an equal volume of dichloromethane. After evaporation of the organic phase, the residue is taken up in a small volume of ethyl acetate and subjected to capillary column gas chromatography with CP-Sil 8 as the stationary phase. The precision was 2.1% at the 3.3 micrograms/ml level of the metabolite in urine (n = 8). The isopentylamino analogue was used as the internal standard.
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PMID:Direct derivatization of alprenolol and its 4-hydroxy metabolite in urine with phosgene and methanol prior to analysis by capillary column gas chromatography. 408 47

Organic materials were extracted from airborne particles by shaking with different solvent systems including acetone, benzene, cyclohexane, dichloromethane (DCM), methanol, a mixture of acetone and DCM and a combination of benzene, cyclohexane and methanol. The solvent-extracted materials were tested for mutagenic activity with the Ames Salmonella/microsomal assay system. Acetone- and cyclohexane-extracted materials gave the highest and lowest mutagenic activities, respectively. Re-extraction experiments confirmed that most of the mutagenic material from air particles cannot be extracted by cyclohexane. The sequential extraction with acetone followed by DCM gave a better mutagenic response than acetone alone or acetone in combination with DCM. Extraction with varying amounts of solvent indicated that 1 ml of acetone per mg of airborne particles reached the maximum recovery of mutagenic material.
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PMID:Mutagenicity studies of ambient airborne particles. I. Comparison of solvent systems. 635 84

Several techniques were evaluated for extracting triphenyl phosphate (TPP), 14C-labeled TPP, cresyl diphenyl phosphate, and tricresyl phosphate isomers (o-TCP, m-TCP, and p-TCP) from fish and sediment samples. Extracts of fish samples were cleaned up by gel permeation chromatography/alumina column chromatography; sediment extracts received alumina treatment only. Compounds were determined by gas-liquid chromatography (GLC) with nitrogen-phosphorus detection. Methanol/Polytron and hexane/ball mill extraction of fish samples fortified at 0.01, 0.1, and 1.0 microgram/g levels gave overall recoveries of the 5 compounds of 89 and 97%, respectively. Methanol recovered more radioactivity (97%) from fish exposed to 14C-TPP in aquaria for 24 h than did hexane from fish exposed for 16 h (79%). Refluxing fortified sediment (0.05 and 0.5 microgram/g) with methanol-water (9 + 1) gave significantly higher recoveries (88%) of the 5 triaryl phosphates than did dichloromethane-methanol (1 + 1) reflux or acetone-hexane (1 + 1) Soxhlet extraction. Recoveries of TPP and o-, m- and p-TCP from fortified river water (0.5, 5.0, and 50 microgram/L) by shaking with dichloromethane ranged from 91 to 118%. Some problems were encountered with interfering GLC peaks at low (microgram/g) levels in fish and sediment extracts despite the use of nitrogen-phosphorus specific detectors.
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PMID:Extraction and cleanup of fish, sediment, and water for determination of triaryl phosphates by gas-liquid chromatography. 720 13

The synthesis of novel acetal thia-cage compounds has been accomplished by the direct substitution for the oxygen atom by the sulfur atom in the reaction of the acetal groups of oxa-cages with Lawesson reagent (LR). Reaction of the tetraoxa-cage compound 2 with LR in dichloromethane at 25 degrees C sequentially gave the monothia-, dithia-, trithia-, and tetrathia-cage compounds 3, 6, 7, and 9. The reaction mechanism for the conversion from oxa-cages into thia-cages was proposed. The diacetal trioxa-cages 18-20 and 24-26 were also transformed into the thia-cages 21-23 and 27-29, respectively. Reaction of the trioxa-cages 34 and 35 with LR under the same reaction conditions gave the thia-cages 36 and 37 with the carbonyl group intact. Treatment of the pentaoxa[5]peristylane 40 with LR in chloroform under supersonic shaking at refluxing temperature gave the monothia[5]peristylane 41 and the dithia[5]peristylane 42. Attempts to synthesize the thia[5]peristylanes from the tetraoxa-cage 51 and the transformation from the parent (unsubstituted) pentaoxa[5]peristylane 46 to the thia-cages have been made. Reaction of the pentaoxa[5]-peristylane 40 with P(2)S(5) in refluxing toluene gave 41, 42, and a rearrangement product 47. The synthesis of new heterocyclic cage compounds 59 and 60, which contain oxygen, nitrogen, and sulfur atoms in the same molecule, was also accomplished.
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PMID:Synthesis of novel acetal thia-cage compounds. 1142 81

The following four methods were compared on the extraction efficiency of 16 EPA (US Environmental Protection Agency) polycyclic aromatic hydrocarbons (PAHs): German method of the Verband Deutscher Landwirtschaftlicher Untersuchungs und Forschungsanstalten (VDLUFA), two methods of the International Organization for Standardization using shaking (ISO A) and Soxhlet extraction (ISO B) and an ultrasonic method. Recovery rates of 16 PAHs were determined in two soils. Extraction efficiency was evaluated in five soils and three sediments. Effect of drying soils and sediments on extraction efficiency was tested using the VDLUFA and the ultrasonic methods. Our study shows that the number of aromatic rings, rather than extraction procedures, significantly influenced recovery rates of individual PAHs. No significant differences in extraction efficiency of the four methods were observed for less polluted samples. For highly polluted soils, extraction efficiency decreased in the following order: VDLUFA method > ISO A > ultrasonic method > ISO B. Influence of soil moisture on extraction efficiency depended to some extent on both solvent used and content of PAHs in samples. A mixture of dichloromethane/acetone (5:1) is recommended for PAH extraction from moist samples when the ultrasonic method is used.
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PMID:Comparative study of extraction methods for the determination of PAHs from contaminated soils and sediments. 1222 95

A simple, very efficient method is presented for routine analysis of herbicide Krovar I (active components bromacil and diuron) in water and soil samples. Water samples were extracted by liquid-liquid extraction with dichloromethane (DCM) as extraction solvent. For soil samples two different extraction techniques were compared: microwave-assisted solvent extraction and a shaking technique using a platform shaker. Extracts were analyzed by high performance liquid chromatography using a water:methanol gradient. Liquid chromatography was coupled with atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) for quantification of bromacil and diuron. Optimization of the APCI-MS was done by using standards in the flow injection analysis mode (FIA). Method detection limit for liquid samples for bromacil is 0.04 microg L(-1) and for diuron 0.03 microg L(-1). Method detection limit for soil samples is 0.01 microg g(-1) dry weight for both compounds. Results of analysis of field samples of water and soil are also presented.
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PMID:Analysis of herbicide Krovar I by liquid chromatography with atmospheric pressure chemical ionization mass spectrometry. 1513 32

Liquid chromatography (LC) with diode array ultraviolet absorbance (DAD UV) detection is used for the simultaneous determination of the fungicide maneb and its main metabolites (ethylenethiourea--ETU, ethylenebis (isothiocyanate) sulfide--EBIS, and ethyleneurea--EU) in tomatoes. The identity of EBIS, one of the main UV degradation products of maneb, was verified by both DAD UV detection and mass spectrometry. The analytes were extracted three times with 3 mL of 1:1:1 acetonitrile-dichloromethane-chloroform by 2 min of mechanical shaking and separated on a C-18 column by gradient elution with an acetonitrile-methanol-aqueous 100mM sodium dodecylsulfate (SDS) mixture. The quantification limits of 0.45, 0.04, and 0.35 mg kg(-1) obtained for maneb, ETU, and EU, respectively, show that the proposed method is suitable for their determination in tomatoes.
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PMID:Simultaneous determination of maneb and its main metabolites in tomatoes by liquid chromatography using diode array ultraviolet absorbance detection. 1533 96

A method of microwave-assisted extraction (MAE) followed by gas chromatography-mass spectrometry (GC-MS) for the determination of organophosphorus pesticides (OPPs) in vegetables has been developed. The OPPs studied were diazinon, parathion and isocarbophos. Several extraction solvents were compared on the MAE efficiency. Dichloromethane gave good recovery, and was chosenfor the procedure. A three-level orthogonal array design was used to optimize the MAE process.Factors affecting the MAE efficiency were considered, including the solvent amount and extraction time.The linear ranges of the method were from 4 ng/g to 400 ng/g for diazinon and parathion, and from 20 ng/g to 400 ng/g for isocarbophos. The detection limits were 0.29 ng/g, 1.70 ng/g and 2.30 ng/g for diazinon, parathion and isocarbophos respectively. Two sets of spiked vegetable samples of 200.0 ng/g and 50.0 ng/g were determined. The recoveries were from 72.2% to 102.0%, and the RSDs were from 1.5% to 11.0% (n = 3). The analytical results agreed quite well with those obtained by conventional extraction with mechanical shaking (EMS). The method is fast and solvent-saving.
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PMID:[Determination of organophosphorus pesticides in vegetables by microwave-assisted extraction/gas chromatography-mass spectrometry]. 1635 85

A novel method was described for detection carbamate pesticides residue in cucumber by immobilizing acetylcholinesterase enzyme in a micro-screen plate with 96 wells based on GA-BSA-gelatin gels. The concentrations of BSA, GA and gelatin in enzyme immobilization solution were optimized and the best concentrations were 5%, 0.5% and 0.1%, respectively. To analyze the pesticides residue 5g cucumber sample was homogenized with 10 mL acetone then an aliquot of 5mL extract was collected in a 10 mL test tube with a cap, into which 2g sodium chloride and 2mL dichloromethane were added in sequence. After shaking, 1 mL of the supernatant aliquot was evaporated by a blower in a small beaker and dissolved by 20% methanol-water solution then 50 microL was piped to a sample well. After incubation 10 minutes the absorbance was detected. The proposed method offered a rapid, simple and inexpensive means to in screen of batch samples. The minimum detection limit of this method was in a range of 0.1-0.2 mg/kg for cucumber samples.
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PMID:[Detection carbamate pesticides residue in cucumber by immobilized acetyicholinesterase enzyme]. 1688 32

A simple and reliable method was developed for analysis of 18 volatile organohalogen compounds (VOHCs) both indoors and outdoors, consisting of VOHC collection by a passive sampler, extraction with toluene by mechanical shaking, and automatic separation analysis by capillary gas-chromatography with electron capture detector (GC/ECD). The passive sampler is a porous polytetrafluoroethylene (PTFE) tube (30.30+/-0.37 mm net collection length, 5.0 mm inside diameter, 0.990 g weight) uniformly packed with activated charcoal (194.4+/-3.8 mg). The procedure was applied to a field survey on indoor and outdoor VOHC pollution in Shizuoka, Japan. Ten VOHCs, including trichloroethylene, tetrachloroethylene, chloroform, carbon tetrachloride, and p-dichlorobenzene, were detected from indoor and outdoor air samples. The ratios of maximum to minimum VOHC concentrations, both outdoors and indoors, were large. The indoor and outdoor concentrations of 1,1-dichloroethylene, dichloromethane, 1,1,1-trichloroethylene, carbon tetrachloride and trichloroethylene were found to be similar. Indoor concentrations of trihalomethanes, p-dichlorobenzene and tetrachloroethylene were higher than those of outdoors.
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PMID:A passive sampler-GC/ECD method for analyzing 18 volatile organohalogen compounds in indoor and outdoor air and its application to a survey on indoor pollution in Shizuoka, Japan. 1896 75


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