Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple, specific and rapid reversed-phase high-performance liquid chromatographic (HPLC) procedure for sotalol determination is described requiring small plasma volumes. The high recovery of sotalol from plasma and the high precision of measurement obviate the need for an internal standard. Plasma samples (300 microliters) were deproteinised with 50 microliters of 70% (w/w) perchloric acid in disposable glass tubes. After vortex-mixing and centrifugation, 30 microliters of 4 M K2HPO4 were added followed by gentle shaking. A 20-microliters aliquot was then injected (by autosampler) for HPLC analysis. Chromatography was performed on a glass-lined 250 mm x 4 mm 5-micron C18 steel column. The mobile phase was 6% (v/v) acetonitrile in 0.08 M KH2PO4 buffer (pH 4.6). The flow-rate was 0.8 ml/min. Detection was by fluorescence with excitation and emission wavelengths at 235 and 310 nm, respectively. The retention time for sotalol was 7.1 min. Calibration was linear from 0.16 to 10 micrograms/ml in plasma (r greater than 0.999 for detector response to sotalol). The minimum concentration for quantitation was 0.08 micrograms/ml [within assay coefficient of variation (C.V.) less than 5%]. Recovery was near quantitative (greater than 98%) and replicate (intra-assay precision was less than 5% C.V.). Analysis of samples (n = 10) at concentrations of 0.42 and 4.2 micrograms/ml gave mean values of 0.44 and 4.3 micrograms/ml, respectively. The inter-assay C.V. values were 4.5 and 2.2%, respectively. Other clinically used antiarrhythmic drugs did not interfere. This assay can be performed using other commercial C18 analytical columns by suitable adjustment of mobile phase flow-rate and acetonitrile composition.
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PMID:Simplified procedure for the determination of sotalol in plasma by high-performance liquid chromatography. 187 2

Sulfonamide drugs are extracted from feed and feed premixes by shaking with 0.15N HCl in 25% methanol. The extract is diluted, clarified, and chromatographed on a reverse phase C18 column. Mobile phases used are methanol-2% acetic acid (35 + 65) and acetonitrile-2% acetic acid (18 + 82) for sulfamethazine (SMT) and sulfathiazole (STZ), respectively. A solution of dimethylaminobenzaldehyde (DMAB) is added to the column eluate and the resulting sulfonamide-DMAB complex is detected at 450 nm. The method was tested for linearity, recovery, and precision across a broad sample range. Recovery was 100.6 +/- 2.3% and 96.3 +/- 1.6% for STZ and SMT, respectively. Linearity was excellent (r2 = 0.9985 for STZ and r2 = 0.9996 for SMT) as was within-day precision (RSD = 2.00% for STZ and 1.52% for SMT). The method was compared with the Bratton-Marshall colorimetric method. Analysis of 14 STZ and 15 SMT samples failed to detect any bias between the 2 methods. Some practical aspects of the use of this technique are discussed.
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PMID:Use of post-column derivatization in liquid chromatographic determination of sulfamethazine and sulfathiazole in feeds and feed premixes. 711 88

A series of ara-CDP-rac-1-S-alkyl-2-O-acyl-1-thioglycerols (3-12), analogues of highly active Cytoros2 (1), was prepared, and solubility, lipophilicity, and structure-activity relationships of these conjugates were investigated. The conjugates with sn-1 alkyl (< C18) and sn-2 fatty acyl (< C14) substituents of the thioglycerol were water-soluble, while those with the sn-1 alkyl (> C14) and the sn-2 fatty acyl (> C16) were sparingly soluble. The latter formed micelles upon sonication. Conjugate 7 containing the sn-1 tetradecyl and the sn-2 palmitoyl (C16) groups formed micelles by both sonication and shaking. The partition coefficients (1-octanol/PBS) of the water-soluble conjugates were about 20 times greater than that of ara-C. The water-insoluble showed a more than 40 times increase. A single dose of the micelle-forming conjugates 7 and 10 produced a significant increase in life span (ILS > 421%) with 50% long-term survivors (> 45 days) in mice bearing ip-implanted L1210 lymphoid leukemia. These results were comparable to those of previous micelle-forming conjugate 1 (Cytoros). In contrast, the water-soluble conjugates at single doses were less effective (ILS 81-386% with 0-33% long-term survivors). However, three divided doses of the water-soluble conjugates were found to be as effective as a single dose of micellar solution of the water-insoluble. The results indicate that conjugate 7 and most of the water-soluble derivatives warrant further investigation.
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PMID:Nucleoside conjugates. 13. Synthesis and antitumor activity of 1-beta-D-arabinofuranosylcytosine conjugates of thioether lipids with improved water solubility. 851 Jan 6

A method capable of simultaneously detecting residues of three sulfonylurea herbicides at microgram/l and microgram/kg level in water and alkaline soils has been described. The method is based on solid phase extraction and HPLC with UV detection. In alkaline soils especially those containing low organic carbon it was possible to extract the herbicides with de-ionised water and no clean up step was needed. Soil samples spiked with technical grade triasulfuron, metsulfuron-methyl and chlorsulfuron were extracted twice by shaking with de-ionised water for one hour and centrifuging at 10,000 rpm for 15 minutes. Supernatants filtered through glass micro-fibre filters were passed through C18 cartridges previously pre-conditioned with methanol and de-ionised water at a flow rate of < 20 ml/min. Residues of the herbicides retained on the cartridge were eluted with acidified methanol. The eluate was analysed by HPLC. A C18 column was used with a mobile phase of methanol/water (40 + 60, V/V for for the herbicide residues were 1.0 microgram/l and 3 micrograms/kg in water and soil, respectively. The average recoveries for water samples ranged from 73-94%, while for soil samples recoveries were 77-97% for the three compounds studied.
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PMID:Simultaneous analysis of triasulfuron, metsulfuron-methyl and chlorsulfuron in water and alkaline soils by high-performance liquid chromatography. 1022 89

A method was developed to quantitate emamectin benzoate in fish feed at levels between 5 and 15 ppm. The active ingredient is extracted from 20 g medicated feed into aqueous-methanolic solvent by overnight shaking. A solid-phase extraction procedure using a 2 g C18 cartridge is then used to concentrate the active residue and remove interfering matrix components. The extracted drug and internal standard are eluted from the cartridge, evaporated to dryness, and reconstituted in methanol. A control feed sample and fortified control working standard are simultaneously prepared. Remaining interferences and sample analysis are further separated on a gradient liquid chromatographic system. Recovery of emamectin benzoate from fortified feeds ranged from 97 to 100%, with a coefficient of variation (CV) of 1.2%. Determination of emamectin benzoate in medicated feeds resulted in CVs ranging from 2.3 to 4.2% and recoveries of 88 to 98% of label claim.
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PMID:Determination of emamectin benzoate in medicated fish feed. 1058 78

A method for determination of riboflavin in animal feeds using liquid chromatography (LC) was developed for feed samples fortified with riboflavin at 1 mg/lb or greater (up to 10,000 mg/lb). Feed samples were extracted in 0.1 N HCl with heating on a steam bath for 30 min, followed immediately by mechanical shaking for 30 min. Sample extracts were diluted to target volume with 2% acetic acid and filtered; riboflavin was determined by LC on a reversed-phase C18 column with 2% acetic acid-acetonitrile (85 + 15) mobile phase for separation and fluorescence detection with excitation at 460 nm and emission at 530 nm. The extraction was compared with that of the AOAC Official Method for riboflavin in food and feed premixes. The 2 method extractions were not significantly different from each other at the 95% confidence level. The developed method also had good linearity over 4 orders of magnitude, recovery of 95-99% from spiked feed samples, a limit of detection of riboflavin at 0.00034 microg/mL in solution, a limit of quantitation of 0.023 mg/lb in feed, and good ruggedness.
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PMID:Reversed-phase liquid chromatographic determination of riboflavin in feeds. 1272 5

A convenient method was developed for determination of sulfathiazole (STZ) in Type C medicated swine feed by reversed-phase liquid chromatography (LC) with post-column derivatization. Addition of extractant solution (0.2N HCl and 1.5% diethylamine in 25% methanol) and an internal standard (IS), sulfamethylthiazole (SMZ), to 5 g sample was followed by mechanical shaking for 1 h. The extract was clarified by chilling, centrifugation, and filtering before injection onto a C18 reversed-phase column. The mobile phase components were 2% acetic acid and 1:1 acetonitrile-methanol (83 + 17%, v/v). Run time was about 20 min. Determination and, largely, the method's selectivity were based on detection at 450 nm of the derivative formed by the post-column reaction of dimethylaminobenzaldehyde with the primary amine of the analyte and IS. The IS, SMZ, differs from STZ by a single substituent methyl group, is stable, and is readily resolved from STZ. Although SMZ is not commercially available, it can be synthesized with relative ease from purchased reagents and will be supplied by the authors to interested laboratories. In single-laboratory validation, linearity was demonstrated over the range of 0.055-550 microg/mL, well beyond the target concentration of 5.5 microg/mL. The estimated limit of detection was 0.04 microg/mL; the calculated limit of quantitation was 0.13 microg/mL (feed concentration of 2.4 g/T or 2.7 mg/kg). Wet-spiking trials with a variety of swine feed matrixes showed recovery to be 100-102% for the intended concentration range, 50-200 g/T, with coefficient of variation (CV) < 2%. The method ruggedness was verified with an overall CV of 2.9%.
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PMID:Determination of sulfathiazole in type C medicated swine feed by reversed-phase liquid chromatography with post-column derivatization. 1450 17

Tetracaine hydrochloride (TH) is nominated as the prohibited ingredients in cosmetics in Japanese Pharmaceutical Affairs Act. So the analytical method for TH was investigated by HPLC. After adding 5 ml of TH solution at 10 microg/ml and 2 ml of salicylic acid solution at 75 microg/ml as the internal standard to 0.5 g of the lotion, the mixture was made up to 10 ml with a mixture of water and methanol (1:1) as the testing solution. Milky lotion was procedured as follows: After adding 5 ml of TH solution at 10 microg/ml and 2 ml of internal standard solution to 0.5 g of the milky lotion, the mixture was made up to 10 ml with a mixture of water and methanol (1:1). Two milliliter of this mixture was placed into a centrifuging tube with a cap and 2 ml of hexane was added. After shaking vigorously and centrifuging, the lower layer was used as the testing solution. In the case of the cream, the other procedures were used: 0.5 g of cream was placed into a 10-ml volumetric flask and 1 ml of tetrahydrofuran was added. After dissolving, the mixture of methanol and water (1:1) was added to make up 10.0 ml. Two milliliter of this mixture was placed into a centrifuging tube with a cap and 2.0 ml of hexane was added. After shaking vigorously and centrifuging, the lower layer was used as the testing solution. The testing solution of 20 microl was analyzed by HPLC using the ODS column (CAPCELL PAK C18 column, 4.6 x 250 mm), the mixture of acetonitrile and 50 mmol/l phosphate buffer(pH 2.0)(7:3) and the detection wavelength of 303 nm. The working curves from 0.5 to 6.0 microg/ml showed a linear line between the concentrations of TH and the peak area ratio. There was no interference of peak of TH from the lotion, milky lotion and cream.
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PMID:[Studies for analyzing prohibited ingredients such as tetracaine hydrochloride in cosmetics]. 1594 Sep

Ginseng saponins (ginsenosides) were extracted from the root and leaves of locally cultivated American ginseng (Panax quinquefolium L.). For the isolation of compounds from plant samples three different extraction methods were utilized: accelerated solvent extraction, the ultrasound-assisted solvent extraction and mechanical shaking assisted solvent extraction. The separation of compounds was achieved with a water-acetonitrile gradient system using a C18 reversed-phase column. Target compounds were identified in MS(2) and MS(3) experiments. The relative distribution of these ginsenosides in each root and leaf extract was established. The limit of detection of the method was less than 30 ng/ml. Recovery of ginseng saponins in spiked samples exceeded 80%, while the relative standard deviation ranged from 7.1 to 9.1%. The total concentrations of ginsenosides were 41 and 13 mg/g in root and leaves.
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PMID:Isolation and determination of ginsenosides in American ginseng leaves and root extracts by LC-MS. 1628 69

A simple and accurate method for the determination of andrographolide and dehydroandrographolide in andrographis paniculata Nees materials and patent medicines with high performance liquid chromatography (HPLC) has been developed. The two components were extracted from powdered samples by shaking with methanol. The resultant extracts were separated within 15 min on a BECKMAN C18 column (4.6 mm i. d. x 250 mm, 5 microm) and with a gradient elution of acetonitrile-water at a flow rate of 0.5 mL/min. The detection wavelength was 225 nm and the injection volume was 20 microL. In gradient elution program the volume fraction of acetonitrile in mobile phase was as follows: 0 min - 1 min, 40%; 1 min - 5 min, 40% - 50%; 5 min - 15 min, 50% - 70%. Both andrographolide and dehydroandrographolide have good linearity in the range of 10 mg/L to 100 mg/L with the correlation coefficients of 0.997 6 and 0.998 6 respectively. This method has been successfully applied for the analysis of andrographis paniculata Nees materials and related patent medicines.
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PMID:[Determination of andrographolide and dehydroandrographolide in Andrographis paniculata nees materials and related patent medicines by reversed-phase high performance liquid chromatography]. 1635 99


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