Determination of phenazopyridine in human plasma by high performance liquid chromatography

Summary A simple, low-cost, sensitive and selective HPLC method was developed for the determination of phenazopyridine in human plasma. The method employs UV detection of phenazopyridine and of the internal Standard at 2 different wavelengths. Calibration curves were linear over a large dynamic range, i.e., within 0.05–10.0 μg mL⁻¹ with limit of quantification of 0.05 μg mL⁻¹, and a limit of detection of 0.01 μg mL⁻¹.     

Determination of amino acids in apple extracts by high performance liquid chromatography

Summary A rapid and sensitive method for the simultaneous determination of primary amino acids in apple is described. After sample preparation, amino acids were derivatized with o-phthaldialdehyde/2-mercaptoethanol and separated on a reversed phase column with a gradient of phosphate buffer-tetrahydrofuran-methanol as the mobile phase. Detection was carried out with a fluorescence detector at excitation and emission wavelengths of 340 nm and 425 nm respectively. Recovery studies showed good results for all substances (91–109%) (with coefficients of variation ranging, from 0.1 to 9.0%). This method was applied to the monitoring of amino acids during the ripening of apples.     

Determination of cortisol in guinea pig urine by high performance thin-layer chromatography, high performance liquid chromatography, and thin-layer chromatography/radioimmunoassay

Summary In order to collect urinary samples from unrestrained guinea pigs, animals were kept in their familiar home cages with wood shavings for bedding. Cortisol was removed from shavings by a simple washing step, and an attempt was made to measure its concentrations by high performance thin-layer chromatography (HPTLC), high performance liquid chromatography (HPLC), or thin layer chromatography/radioimmunoassay (TLC-RIA). After intramuscular administration of 25 mg cortisol, cortisol excretion increased from about 20–30 μg/day to 400–500 μg/day (HPTLC: 531 μg/day, HPLC: 493 μg/day; TLC-RIA: 394 μg/day). Similarly, the treatment of the animals with 20 IU ACTH resulted in an augmented cortisol excretion, with mean values of 294 μg/day (HPTLC), 256 μg/day (HPLC) and 143 μg/day (TLC-RIA), respectively. The present study shows, for the first time, that cortisol excretion in unrestrained laboratory animals can be determined. Whilst the cortisol values measured by HPTLC and HPLC agree, the amounts measured by TLC-RIA were significantly lower. These differences are probably due to the presence of substances in urine or shavings which interfere with the radioimmunological determination. Hence, cortisol should be determined either by HPTLC or HPLC. Beside having a desirable specificity, these methods are more suited than TLC/RIA for steroid analysis since they confer the possibility of measuring additional steroids (e.g. precursors and/or metabolites of cortisol) in a single urine extract. This is especially the case for the HPTLC method since substances can be transformed into fluorescent derivatives.     

Temperature-dependent separation of bryostatin 18 and 10 by high performance liquid chromatography

Summary The temperature-dependent separation of bryostatins by HPLC was examined on an octadecyl bonded stationary phase, using column temperatures between 0 and 40°C and mobile phase temperatures from 0 to 25°C. The retention time and resolution of bryostatins changed drastically and separation improved with decreasing temperature. A column temperature of less than 5°C and a mobile phase temperature of less than 15°C is recommended for a good resolution of bryostatins for routine work.     

Comparison of provitamin A determination by normal-phase gravity-flow column chromatography and reversed-phase high performance liquid chromatography

Summary The provitamin A content of some food samples was determined by methods involving MgO: Hyflosupercel gravityflow column chromatography (GFCC) and reversed phase high performance liquid chromatography (HPLC), the quantitation being done by external standardization (HPLC-ES) or internal standardization (HPLC-IS) with Sudan. The results obtained with - and -carotene in carrots, -carotene and -cryptoxanthin in papaya and -carotene in tomato and kale agreed well, showing that any of the these techniques can be used, provided the analysis is done under optimum conditions. Good separation of the different provitamins using GFCC depends on the analyst's skill and visual acuity. HPLC-ES required a constant supply of provitamin standards, thus the varying purity of commercially available standards and the high instability of these compounds could pose grave problems. Due to the stability of Sudan, HPLC-IS appeared to be the method of choice although passage of the extract through a MgO: Hyflosupercel minicolumn was required prior to injection to separate chlorophylls, dihydroxy- and polyoxycarotenoids which would otherwise elute with Sudan. Nonconformity of the Sudan structure to those of the provitamins did not effect the quantitative results. The chromatographic separation, identity and quantification of the provitamins could be more easily established by using HPLC-IS, complemented with GFCC.     

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.     

A rapid method for the determination of methoprene in tobacco by high performance liquid chromatography

Summary A rapid sample preparation procedure combined with a short reversed-phase HPLC separation for the quantitation of methoprene residue in tobacco samples is described. A ground tobacco sample of 0.5 g is mixed with 3 mL of 2-propanol. The mixture is extracted for twelve minutes with the aid of sonication at an elevated temperature (45–55°C) and then filtered through a 0.45 m disposable filter prior to injection on HPLC. No sample cleanup or solvent evaporation step is required. Chromatographic analysis is performed on a C-18 column and the analysis time is 12.5 minutes. The detection limit for methoprene in tobacco samples is one part per million (g/g).     

高效液相色谱法测定铝酸钠溶液中的有机酸

建立了铝酸钠溶液中有机酸的高效液相色谱测定方法。铝酸钠溶液样品经简单处理后,在Kromasil C18色谱柱上,以KH2PO4-H3PO4-甲醇-水为多元流动相,等度洗脱,在10 min内可完成草酸、酒石酸、乙酸、丁二酸、丁烯二酸和戊二酸等有机酸的分离测定。方法线性关系良好（r=0.9952-0.9999）,样品加标回收率在80.2%-127.6%之间,相对标准偏差均在6.9%以下。     

Separation of gonadal steroid epimers using high performance liquid chromatography

Summary Chromatographic separation of biologically active epimeric steroids was carried out using a combination of normal and reversed phases. Testosterone (17-OH) was separated from its 17-OH epimer epitestosterone using a normal phase silica column whereas their reduced 5-metabolites were separated on a reversed phase system. The separation of other gonadal steroids including the epimers 20- and 20-hydroxypregn-4-en-3-one is also discussed. The technique is particularly useful for separating mixtures of naturally occurring steroid epimers prior to radioimmunoassay.     

Determination of biogenic amines in wines and beers by high performance liquid chromatography with pre-column dansylation and ultraviolet detection

Summary A sensitive high performance liquid chromatographic method for the simultaneous determination of eleven biogenic amines, using 1,7-diaminoheptane as internal standard, has been developed. The method involves pre-column derivatization of the amines with dansyl chloride and subsequent solid phase extraction of the derivatives through C18 cartridges. The derivatization and solid phase extraction procedures were optimized. The separation of dansylamides was achieved on an Inertsil ODS-3 column (250×4 mm I.D. 5 μm) using a 35-min gradient elution method with a binary system of acetonitrile-water, a flow rate of 1 mL.min¹ with UV detection at 254 nm. Linearity of derivatization was obtained for concentrations ranging from 0.025 to 3.0 mg.L¹. The within- and between-day relative standard deviations ranged from 0.4 to 5.7% and 0.6 to 7.3% respectively. The overall process was successfully applied to identify and quantify biogenic amines in white, red and Retsina Greek wines and Greek beers, after their treatment with polyvinylpyrrolidone.     

Analysis of flavonol aglycones in wine extracts by high performance liquid chromatography

Summary An HPLC isocratic elution procedure which allows the separation of flavonol aglycones in wine without interference from other phenolics of low molecular weight is described. The method has been applied to the separation, identification and quantitative estimation of flavonol aglycones in ether extracts of different Spanish wines (red and white table wines and Sherry finos). The results suggest that these determinations, associated with other analyses, would permit the chemical characterization of wines.     

High-performance liquid chromatography of 8-hydroxyquinoline chelates of aluminium and cobalt(III)

Summary The 8-hydroxyquinoline chelates of Co(III) and Al(III) may be separated by high-performance liquid chromatography using a silica column and 5% methanol in chloroform as mobile phase. Using detection at 254 nm, the method provided detection limits of 0.9 ng of Co(III) and 17 ng of Al(III) in a 10 mm³ injection.     

Sensitive determination of cinnarizine in human plasma by high performance liquid chromatography and fluorescence detection

Summary A sensitive high performance liquid chromatographic method has been developed for the determination of cinnarizine in human plasma. Cinnarizine and clocinizine (internal standard) were extracted from acidified plasma (pH 4.7) into carbon tetrachloride and the organic layer was evaporated. The products were separated on a Microspher C18 (3 m) column, using a mixture of 0.04 % triethylamine in 0.01 M ammonium dihydrogen phosphate (NH₄H₂PO₄), pH adjusted to 4.2 with orthophosphoric acid (H₃PO₄), and acetonitrile (2080, v/v) as mobile phase, at a flow rate of 1 ml/min at 40°C. Fluorescence detection (_ex = 245 nm, _em = 310 nm) was used; the detection limit was 0.5 ng/ml under the conditions used, and the calibration curve linear in the concentration range evaluated (1–60 ng/ml). The assay has been used to measure cinnarizine concentrations in plasma after oral administration to volunteers.     

Determination of myristicin in rat serum samples using microbore high performance liquid chromatography with column-switching

Summary A microbore high-performance liquid chromatographic method with column-switching was developed for the analysis of myristicin from rat serum without prepurification. Deproteinization, fractionation, concentration and separation of analyte were carried out by appropriate switching of columns and using solvent mixtures. The method showed excellent precision, accuracy and speed with a detection limit of 10 ng mL⁻¹ from 25 μL of serum. The total analysis time per sample was 25 min and the coefficients of variation for intra- and inter-assay were less than 1.8%.     

Determination of caffeoylquinic acids and flavonoids inCynara scolymus L. by high performance liquid chromatography

Summary The main phenolic compounds in dried extracts fromCynara scolymus (artichoke)—monocaffeoylquinic acids, dicaffeoylquinic acid, and flavonoids–have been separated by high-performance liquid chromatography. By use of a narrow bore C₁₈ column and an acidic mobile phase this HPLC method enabled improved separation within 31 min with significantly reduced solvent consumption compared with other methods. The method was validated to demonstrate its linearity, precision, accuracy, and robustness. Twelve commercial samples were analyzed. Monocaffeoylquinic acids were the most abundant phenolic compounds; the amounts present ranged from 0.48 to 4.24%. The amounts of dicaffeoylquinic acids and flavonoids were smaller—from 0.03 to 0.52%. The method is a good combination of efficiency and economy and should be especially useful for commercial applications.     

High performance liquid chromatographic analysis of Patent Blue V in cheese

Summary The HPLC method developed for the analysis of the dye Patent Blue V in extracts from cheese is sufficiently sensitive to detect and measure concentrations above 0.1 ppm with a standard deviation of 3%. The extraction procedure described gives a recovery from cheese of about 80%. The method has been applied to commercial samples of cheese and a concentration of the dye of about 0.12 ppm was measured in one case.     

High performance liquid chromatographic analysis of patent blue V in cheese

Summary The HPLC method developed for the analysis of the dye Patent Blue V in extracts from cheese is sufficiently sensitive to detect and measure concentrations above 0.1 ppm with a standard deviation of 3 %. The extraction procedure described gives a recovery from cheese of about 80 %. The method has been applied to commercial samples of cheese and a concentration of the dye of about 0.12 ppm was measured in one case.     

反相高效液相色谱法同时测定对苯氧基苯酚和对氯苯酚

建立了一种同时测定对苯氧基苯酚和对氯苯酚的反相高效液相色谱方法。采用Diamonsil(钻石)C18(250 mm×4.6 mm i.d.,5μm)色谱柱,以甲醇-水(V(甲醇):V(水)=8∶2)为流动相,在波长为230 nm处进行检测。对苯氧基苯酚和对氯苯酚在20~230μg/mL范围内,峰面积与质量浓度呈良好的线性关系,相对标准偏差RSD分别为0.26%、0.53%,回收率在99.0%~101%之间。方法可用于对苯氧基苯酚的合成工艺研究及成品质量控制。