Determination of methylprednisolone in rat tissue by high-performance liquid chromatography

Methylprednisolone was determined in various types of rat tissue following an intravenous injection of methylprednisolone sodium succinate. Two modes of tissue work-up were investigated: digestion with subtilisin Carlsberg, a proteolytic enzyme, and homogenization with methanol. The final determination was by reversed-phase high-performance liquid chromatography with dexamethasone as internal standard. The extraction yields of methylprednisolone and dexamethasone from tissue homogenate and the extraction yield of methylprednisolone after incubation with viable tissue were determined. The experiments show that methylprednisolone and the internal standard are extracted in similar yields from tissue homogenates and that methylprednisolone can be recovered in a good yield after incubation with viable tissue, provided that the tissue does not have a high metabolic activity. There was a good agreement between the analytical results from the two different types of tissue work-up. The method of analysis proved feasible for pharmacokinetic work.     

Determination of carvedilol in human cardiac tissue by high-performance liquid chromatography

A new high-performance liquid chromatographic method has been developed for the determination of the beta-receptor blocker carvedilol in human cardiac tissue. After homogenizing tissue samples in a microdismembrator, carvedilol and the internal standard naftopidil are extracted with acetone. The extract is evaporated to dryness and reconstituted in a potassium acetate buffer of pH 3.5. Samples are cleaned up with solid-phase extraction columns. Carvedilol and the internal standard show recoveries of 69.8 +/- 12.2% and 63.9 +/- 9.34%, respectively. The linearity range for carvedilol is 0.01-0.35 ng/mg (parts per billion) tissue (wet weight), and the limit of quantitation is 0.01 ng/mg. The percentage coefficient of variation of the intra-assay varies between 1.45 and 5.38% and the interassay between 4.25 and 6.96%. To use as an application of the assay, the cardiac carvedilol tissue level in a patient on oral carvedilol therapy for congestive heart failure is reported.     

Determination of aprotinin by high-performance liquid chromatography

Summary A highly accurate and reproducible method for the determination of aprotinin (bovine pancreatic trypsin inhibitor) by HPLC is described. In the experiments, the relative standard deviation was 1.2% and detection limit 1 FIP-U cm^–3. Also, the method is quick and selective and active ingredients from difference source correlate well with enzymatic method. Analyses at different laboratories can be compared directly.     

Determination of thiamine by high-performance liquid chromatography

High-performance liquid chromatographic methods for the determination of thiamine (vitamin B1) in foodstuffs or biological tissues and fluids are outlined and discussed. The methods are often similar and interchangeable, sample extraction and clean up procedures being the major difference. Most of the methods use either ultraviolet or fluorescence detection. Fluorescence detection requires either precolumn or postcolumn oxidation of thiamine to thiochrome. A number of methods are recommended and problems with standardization are emphasized.     

Determination of mitomycin C in urinary bladder tissue by reversed-phase high-performance liquid chromatography

A procedure was developed for the determination of an anticancer drug of mitomycin C (MMC) in urinary bladder tissue samples by reversed-phase high-performance liquid chromatography with spectrophotometric (365 nm) and mass-spectrometric detection with detection limits of 50 and 10 ng/mL, respectively (signal-to-noise ratio = 3). The tissue samples were homogenized and solid-phase extraction was performed on a DSC-18 cartridge. The procedure was used for comparing the effectiveness of the MMC penetration into the urinary bladder tissue by passive diffusion and by intravesical drug electrophoresis. EDMA increases the rate of mitomycin penetration into urinary bladder walls by 3 to 5 times with respect to passive diffusion.     

高效液相色谱法测定鸡组织中苯并咪唑类药物残留标志物

建立了高效液相色谱同时测定鸡肉、鸡肝脏和鸡肾脏中11种苯并咪唑类药物残留标志物的方法。样品采用乙腈提取，经正己烷脱脂后以MCX固相萃取小柱净化，净化液浓缩处理后采用Atlantis T₃色谱柱分离，以甲醇-1%（v/v）乙酸水溶液为流动相进行梯度洗脱，紫外检测波长为292 nm，外标法定量检测。目标化合物在25~1000 μg/L范围内线性良好，定量限为50 μg/kg；在不同添加水平下目标化合物的回收率为70.91%~103.21%，相对标准偏差为1.48%~10.08%（n=6），精密度和准确度均符合要求，能够满足鸡组织中苯并咪唑类药物残留标志物的检测要求。     

Determination of ephedra alkaloids by high-performance liquid chromatography

Summary Two simple methods were developed for the simultaneous determination of six alkaloids (ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine and methyl-pseudoephedrine) inEphedrae Herba by high-performance liquid chromatography. The first method was carried out by using a Cosmosil 5C₁₈-MS column with a gradient solvent system consisting of a phosphate buffer and acetonitrile, and detection at 210 nm. The contents of alkaloids in non-pretreated ephedra herb extracts could be determined easily in 50 min. Alternatively, the alkaloids could be determined within 35 minutes by using a Cosmosil 5C₁₈-MS column with an isocratic solvent system of a sodium dodecyl sulfate-acetonitrile solution. The two methods are compared and discussed.     

Determination of sulfur anions by high-performance liquid chromatography

Sulfite, sulfate, sulfide and thiosulfate ions are separated by high-performance liquid chromatography under acidic conditions on commercial low-capacity silica-based and resin-based anion-exchange columns with potassium hydrogenphthalate as the eluent. The ions are detected by using indirect ultraviolet absorption or conductivity detectors. The effects of concentration, pH and flow rate of the eluent on the retention times of sulfur anions are reported. The resin-based column is preferable to the silica-based column for separations of sulfur anions.     

Determination of streptomycin in serum by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed for monitoring the serum concentration of streptomycin. The method includes clean-up using a Sep-Pak C18 cartridge and quantitation using dihydrostreptomycin as an internal standard. Streptomycin and dihydrostreptomycin were separated by reversed-phase ion-pair chromatography on LiChrosorb RP-18 and detected by UV absorption (195 nm). The calibration graph of serum streptomycin concentration was linear over the range 5-50 micrograms/ml. Streptomycin was added to serum at the level of 20.0 micrograms/ml and its concentration was determined to be 18.9 micrograms/ml with a coefficient of variation of 2.07% (n = 5). The clinical application of this method was confirmed by comparison with fluorescence polarization immunoassay.     

Determination of folates in seaweeds by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatography (HPLC) method, with a combination of fluorescence and ultraviolet detectors, to determine the folate forms present in commercial macroalgae products form northwest Spain as part of nutritional studies in dehydrated and canned seaweeds is reported. The method includes extraction of folates from seaweed by heat treatment, deconjugation of folate polyglutamates by incubation with hog kidney conjugase and purification by solid-phase extraction (SPE) with strong anion-exchange (SAX) cartridges. Separation was achieved with a Tracer Extrasil ODS 5 microm 25 cm x 0.4 cm column using acetonitrile and potassium phosphate buffer (pH 2.21 as mobile phase. Good results were obtained with respect to repeatability (relative standard deviation (R.S.D.) < or = 4.12%) and recovery (> or = 90.80%). The amount of folate (as folic acid) in the six species ranged from 61.4 to 161.6 microg per 100 g dry mass. In all the seaweeds studied (Himanthalia elongata, Laminaria ochroleuca, Palmaria spp., Undaria pinnatifida and Porphyra spp. and Saccorhiza polychides) the single most abundant form is 5-CH3-H4-folate, except Porphyra and Himanthalia.     

Determination of aldehydes in fish by high-performance liquid chromatography

A new analytical method to determine trace volatile aldehydes isolated from the headspace of fish meat at room temperature by high-performance liquid chromatography (HPLC) in the form of 2,4-dinitrophenylhydrazone (DNPHo) derivatives has been developed. Aliquots (50 g) of the fish purée were introduced into a 500-mL glass recipient and were purged with N2 for 40 min through two SEP-PAK C18 cartridges (connected in series) coated with an acid solution of 2,4-dinitrophenylhydrazine. The cartridges were then eluted with acetonitrile (2 mL) and the 2,4-DNPHo formed was quantitated by HPLC-UV analysis using a Zorbax C18 column. The isolated compounds from the dynamic headspace sampling of four kinds of fish species were saturated aldehydes, formaldehyde, acetaldehyde, propanal, butanal, pentanal, and hexanal. Under optimized conditions the detection limits of the HPLC method were in the range of 0.75 nmol/g (formaldehyde) to 2.19 nmol/g (hexanal). The calibration curves were linear in the concentration range from 1.3 nmol/mL to 12.5 nmol/mL. Propanal and acetaldehyde were the major carbonyl compounds identified (ranging from 3.9 nmol/g and 10 nmol/g). This study has revealed the widespread occurrence of formaldehyde, acetaldehyde, propanal, butanal, pentanal, and hexanal in fish meat.