气相色谱法测定生物制品中苯酚含量

本文采用气相色谱法测定了几种生物制品中苯酚含量。样品无需进一步处理,加入内标液后直接上柱测定,色谱峰形良好,线性范围宽,平均回收率和变异系数分别为１０１．８％ 和１．０８５％ ,最小检测限为１０ μｇ／ｍ ｌ,本法操作简单,样品用量少,可作为测定生物制品中苯酚含量的一种常规方法。     

A sensitive gas chromatographic method for determination of protein-associated sulfur

A sensitive method for the determination of elemental sulfur bound to serum albumin and other proteins has been devised. The sample is treated with a hexane solution of triphenylphosphine, and the triphenylphosphine sulfide formed is determined by gas chromatography with a flame photometric sulfur detector. The detection limit of the method is 0.3 microM albumin-associated sulfur. Protein-associated sulfur was not detected in plasma from rats or normal human beings, findings that do not support an earlier suggested transport function of serum albumin for sulfur. Significant amounts of protein-associated sulfur, however, were found in certain rat tissues.     

A microliter method for the gas chromatographic determination of long-chain non-esterified fatty acids in human serum or plasma

Non-esterified fatty acids (NEFA) from C₁₂ to C₂₄ are assayed in human serum or plasma in a four-step procedure: extraction, volume reduction, methylation and gas chromatography. NEFA are extracted with chloroform—heptane—methanol from 50–100 μl of serum or plasma buffered with phosphate. After adding ethyl acetate the volume of the extract is reduced under partial reflux to 5–7 μl. Potassium carbonate, methyl iodide and a crown ether are added to the dry concentrate and the NEFA are selectively methylated with a yield of 100% by heating in a microrefluxer for 10 min. Gas chromatography is carried out with 1 μl of the reaction mixture on a packed column by temperature-programmed operation. Thirteen individual fatty acids are determined in sera of normal adults. The coefficients of variation for 24 determinations of a pooled serum were 2.7% for the total NEFA content and 3–10% for most of the individual NEFA.     

Quantitative thin-layer chromatographic method for the determination of procainamide and its major metabolite in plasma

A sensitive and accurate spectrodensitometric method was developed for the determination of procainamide and its major metabolite, N-acetylprocainamide, in plasma. The method involves extraction into organic solvent at alkaline pH, separation by thin-layer chromatography and direct measurement of the adsorbance of the compounds on the plate at 275 nm. Quantities as low as 10 ng could be measured and a linear relationship was obtained between peak areas and amounts of the compounds in the spots from 10 to 200 ng. The recovery of both drugs from plasma was from 95.4 to 104.8%. The method is sensitive and specific, and procainamide was well separated from N-acetylprocainamide at all investigated concentrations. The method is recommended for clinical assays and pharmacokinetics studies.     

A gas chromatographic method for the determination of inositol monophosphates in rat brain

Regional levels of cerebral inositol-1-phosphate (Ins1P), an intermediate in phosphoinositide (PI) cycle, were readily detected with a new gas chromatographic (GC) method. GC analysis of trimethylsilyated Ins1P and myo-inositol-2-phosphate with a fused silica capillary SE-30 column and flame ionization detection was linear at picomolar range (pmol/l) with a sensitivity to a level of 2 pmol. Also, inositol monophosphates and glucose-6-phosphate are separated in unstimulated brain tissue. The mean recovery of the method is 98±5.2%. Ins 1P levels were higher in frontal than in caudal regions in control brains. Lithium treatment increased the levels of Ins1P throughout the brain but mostly in frontal brain regions and in the hippocampus. The present GC assay to measure the accumulation of Ins1P, an index for the activity of PI signalling, may be suitable for exploring regional differences in cerebral receptor-coupled PI signalling in vivo.     

Liquid chromatographic method for the determination of ticlopidine in human plasma

A simple high-performance liquid chromatographic method for determination of ticlopidine in human plasma using ultra violet detection was developed. The separation of the investigated compound and internal standard was achieved on a C₁₈ BD column with a 0.01 M potassium dihydrogen phosphate buffer (pH 4)–acetonitrile–methanol (20:40:40, v/v) mobile phase. The detection was performed at 215 nm. The compounds were isolated from plasma by Bond Elut C₁₈ solid-phase extraction, the mean absolute recovery was 84.9%. The limit of quantitation was 10 ng ml⁻¹, the limit of detection was 5 ng ml⁻¹. The bioanalytical method was validated with respect to linearity, within- and between-day accuracy and precision, system suitability and stability. All validated parameters were found to be within the internationally required limits. The developed analytical method for ticlopidine was found to be suitable for application in pharmacokinetic studies and human drug monitoring.     

Liquid chromatographic method for the determination of rizatriptan in human plasma

A high-performance liquid chromatographic (HPLC) method with fluorescence detection has been developed for the determination of rizatriptan in human plasma. Following a single-step liquid-liquid extraction with methyl tertiarybutyl ether, the analytes were separated using a mobile phase consisting of 0.05% (v/v) triethylamine in water (adjusting to pH 2.75 with 85% phosphoric acid) and acetonitrile (92:8, v/v). Fluorescence detection was performed at an excitation wavelength of 225nm and an emission wavelength of 360nm. The linearity for rizatriptan was within the concentration range of 0.5-50ng/ml. The intra- and inter-day precisions of the method were not more than 8.0%. The lower limit of quantification (LLOQ) was 0.5ng/ml for rizatriptan. The method was sensitive, simple and repeatable enough to be used in pharmacokinetic studies.     

Sensitive gas chromatographic determination of trifluoperazine in human plasma

Plasma trifluoperazine levels of patients taking a single 20-mg dose of trifluoperazine were measured by a sensitive and linear method. The low detection limit of 0.1 ng/ml plasma was obtained through use of a highly sensitive nitrogen—phosphorus detector combined with an efficient extraction method. Recovery of trifluoperazine added to human plasma was 96%. Data are presented on the stability of trifluoperazine in refrigerated human plasma.     

Liquid chromatographic method for the determination of rosiglitazone in human plasma

A robust, accurate and sensitive high-performance liquid chromatographic method for the determination of rosiglitazone (I) in human plasma has been developed. Pioglitazone (II) was used as internal standard. Both I and II are extracted from plasma using a liquid-liquid extraction procedure. Isocratic separation of I and II is carried out using a reversed-phase Zorbax SB C(18), 15-cm column with mobile phase consisting of methanol and a mixed phosphate buffer (10 mM monobasic sodium phosphate and dibasic sodium phosphate, pH adjusted to 2.6 with ortho-phosphoric acid) in the ratio 30:70 (v/v) and quantified by UV detection at 245 nm. Linearity was established over the range 5-1250 ng/ml using 1 ml human plasma. The method is specific, the endogenous components in plasma do not interfere with I and II. C.V. (%) of intra-day samples is less than 5.0% at four concentrations tested namely 5, 10, 500 and 1000 ng/ml. Similarly, over the same nominal concentrations, the precision of inter-day (5 days) samples also results in C.V. (%) less than 5.0%. The recoveries of I and II from human plasma were about 79 and 60%, respectively. This method can be used for routine clinical monitoring of I.     

High-performance liquid chromatographic method for the determination of dolichols in tissues and plasma

High-performance liquid chromatographic methods for the determination of dolichols in tissues and plasma have been developed. The tissue concentration of dolichols was measured by high-performance liquid chromatography with uv detection and plasma levels of dolichols were determined fluorometrically after derivatization with anthracene-9-carboxylic acid. In both methods, 2,2-didecaprenylethanol was used as an internal standard. The method with fluorescence detection was sufficiently sensitive to measure the concentration of dolichols in human plasma.     

Stereospecific gas chromatographic method for determination of methadone in serum.

rac-Methadone is used clinically for the chronic maintenance treatment of heroin addiction and for the relief of pain. As the pharmacological activity of methadone is due primarily to the (-)-(R)-enantiomer, stereospecific measurements of methadone serum concentrations in methadone-treated patients are expected to be more relevant for clinical studies than earlier described total drug measurements. This study describes a stereospecific gas chromatographic (GC) method for the determination of methadone in serum. The extracted methadone was derivatizised with (-)-menthyl chloroformate. The diastereometric derivatives were analysed by GC on a capillary column and detected with a nitrogen-phosphorus detector. The resolution factor obtained for the methadone enantiomers was 1.1 with a relatively short time of analysis (30 min). By analysing the pure (-)-(R)-enantiomer, no racemization was seen during the analysis. The lower limit of quantitation was 75 nmol/l for each enantiomer. Measurements of the ratio between (-)-(R)- and (+)-(S)-methadone concentrations in serum from five methadone-treated patients showed interindividual differences (range 0.5-1.1). The patient results correlated well with those from another GC method measuring total methadone.     

Sensitive high-performance liquid chromatographic method for the determination of coumarin in plasma

A high-performance liquid chromatographic method was developed for the determination of coumarin in plasma at low concentrations. The method involves a single-step extraction of the alkalinized sample with hexane and subsequent evaporation of the organic phase in the presence of hydrochloric acid to collect and concentrate the coumarin. Analysis of the acidic phase was performed on a C₈ column and coumarin was detected by measuring the UV absorbance at 275 nm. The limit of detection was 0.3 μg l⁻¹. The assay was used to study the evolution of concentrations of coumarin in one volunteer after oral administration of a single 10-mg dose.