HPLC coupled with ICPMS for the determination of metalloporphyrins in coal extracts

The HPLC-ICPMS determination of gallium porphyrins in various coal extracts is described. The HPLC-ICPMS results are compared with results obtained by HPLC-UV/VIS. The presence of gallium has been confirmed in all the porphyrin macrocycles.     

Development of a tandem thin-layer chromatography-high-performance liquid chromatography method for the identification and determination of corticosteroids in cosmetic products

A solid-phase extraction clean-up and and a liquid chromatographic method with ultraviolet detection were developed for the analysis of 51 corticosteroids in cosmetic samples in order to screen commercial samples for the presence of undeclared synthetic corticosteroids. A thin-layer chromatographic analysis was carried out on silica gel plates, using different eluants and detection reagents. When such a preliminary chromatographic separation gave some indications about the presence of steroid compounds, the methanol extracts from real samples were applied to a solid-phase extraction C₁₈ cartridge, and the analytes eluted with ethyl ether. The high-performance liquid chromatographic separation was then carried out for the identification and determination of the analytes using a Purospher RP-18 column, an isocratic or a gradient elution with a mixture acetonitrile-water and a photodiode-array detector. The accuracy of the method was determined by spiking experiments on home-made cosmetic samples. The analytical recoveries were satisfactory.     

Analysis of catecholamines and their metabolites in adrenal gland by liquid chromatography tandem mass spectrometry

Two simple, rapid and specific analytical methods for 13 catecholamines and their metabolites have been developed based on liquid chromatography tandem mass spectrometry in a multiple reaction monitoring mode. Tyrosine, dopamine, dihydroxyphenylalanine, epinephrine, norepinephrine, 3-methoxytyramine, normetanephrine, metanephrine and isoproterenol (internal standard) were separated on a Kromasil™ Cyano analytical column by a mobile phase consisting of 60% (v/v) acetonitrile and 40% (v/v) water adjusted with formic acid to pH 3.0, and detected by positive ionization electrospray tandem mass spectrometry. While vanillymandelic acid, 3,4-dihydroxymandelic acid, homovanillic acid, 3,4-dihydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenylglycol and 5-hydroxy-2-indolecarboxylic acid (internal standard) were separated on a reversed-phase Shim-Pak VP-ODS column with the mobile phase of 60% (v/v) acetonitrile, and 40% (v/v) water adjusted with formic acid to pH 4.5 and detected in the negative ionization electrospray tandem mass spectrometry. The influence of various parameters such as column type and mobile phase composition on separation and sensitivity were investigated. The limits of detection were in the range of 0.5-20 ng mL⁻¹. The mean recoveries determined from three different concentrations of each analyte were above 85.4%. The precision of the method calculated as relative standard deviation was lower than 5.3%. Deduced from the results of real sample analysis, adrenal gland synthesizes and stores the catecholamine hormones norepinephrine and epinephrine.     

HPLC determination of piperine in pepper and in pepper extracts

Summary HPCL quantitation of piperine in pepper and in pepper extracts is described. This is optimised on nitratedsulphonated phenyl silica gel with phloracetophenone as internal standard.     

Preparative HPLC for analysis of mineralocorticoids in human plasma

Summary A method has been developed to measure simultaneously in human plasma the mineralocorticoids and glucocorticoids involved in mineralocorticoid excess. Briefly: plasma extracts were chromatographied in a fully-automated procedure on a lichrospher-diol column using a hexane: isoproanol: trithylamine gradient. Eluates were collected on a preprogrammed fraction collector. Final quantification was achieved by RIA on the selected fractions. This procedure allowed: 1) the separation of each measured steroid from plasma contaminants; 2) precise collection; 3) quantification of mineralocorticoids with a precision and sensitivity equivalent to that of direct methods; and 4) improved specificity.     

Micellar electrokinetic chromatography for simultaneous determination of six corticosteroids in commercial pharmaceuticals

We have developed a micellar electrokinetic chromatography (MEKC) method using bile salts for the simultaneous determination of six corticosteroids, including betamethasone, cortisone, prednisolone, 6alpha-methylprednisolone, triamcinolone, and prednisone. The separation was performed using borate buffer containing sodium cholate and sodium deoxycholate. Several parameters were studied, including bile salt concentrations, concentrations and pH of borate buffer, and analytical voltages. In method validation, calibration curves were linear over a range of 10-100 microM for each corticosteroid. The RSD (relative standard deviation) and RE (relative error) were all less than 5% for intra- and interday assays. The limit of detection of each analyte was 5 microM. The recoveries were greater than 95%. Application of this method for quality control of commercial tablets also proved to be feasible. All analytical values fall within the labeled amount of 90-110% for betamethasone and prednisolone, and of the labeled amount of 92.5-107.5% for 6alpha-methylprednisolone, as required by the United State Pharmacopeia 25 (USP 25).     

The direct combination of HPLC solute focusing with supercritical fluid chromatography and mass spectrometry to enhance sensitivity and improve identification of trace components in polar solvent extracts

A system for combining normal and reversed phase high-performance liquid chromatography solute focusing with packed column supercritical fluid chromatography and supercritical fluid chromatography–mass spectrometry has been developed. The technique has been used to identify paracetamol and stanozolol in spiked plasma extracts and its utility for the analysis of a sample from a process waste stream is illustrated.     

高效液相色谱整体柱在药物分离分析中的应用进展

本文对高效液相整体柱在药物分离分析方面的应用进行了综述.主要介绍了以烷氧基硅烷为主要原料,采用溶胶-凝胶法制备的硅胶整体柱,由于其具有微米级通孔结构和大的比表面积,他们在高效、快速分离小分子物质方面得到广泛地应用.对于聚合物整体柱,主要介绍了包括分子印迹聚合物在内的有机聚合物整体柱在药物分离、生物样品的处理等方面的应用.     

Comparison of high performance TLC and HPLC for separation and quantification of chlorogenic acid in green coffee bean extracts

Two chromatographic methods, high-performance TLC (HPTLC) and HPLC, were developed and used for separation and quantitative determination of chlorogenic acid in green coffee bean extracts. For HPTLC silica gel Kieselgel 60 F 254 plates with ethyl acetate/dichlormethane/formic acid/acetic acid/water (100:25:10:10:11, v/v/v/v/v) as mobile phase were used. Densitometric determination of chlorogenic acid by HPTLC was performed at 330 nm. A gradient RP HPLC method was carried out at 330 nm. All necessary validation tests for both methods were developed for their comparison. There were no statistically significant differences between HPLC and HPTLC for quantitative determination of chlorogenic acid according to the test of equality of the means.     

Comparison between HPLC and HPTLC densitometry for the determination of icariin from Epimedium koreanum extracts

Dry extracts of the aerial parts of Epimedium koreanum were quantified by HPLC and high performance TLC (HPTLC). A gradient HPLC method was used for the quantification of the prenylflavone glycoside icariin at 270 nm. A direct HPTLC assay was developed for the determination of icariin at 270 nm. The UV detection of both analytical assays were used to examine the purity of icariin peaks and compared with the standards. The assays provide good accuracy, reproducibility, and selectivity for the quantitative analysis of icariin. The icariin contents of five different dry extracts were compared by HPLC and HPTLC densitometry. The quantitative results of both analytical methods did not show any statistically significant differences between them, although a trend to slightly lower mean values could be found for the HPLC method.     

Pre-column derivatization of rofecoxib for determination in serum by HPLC

An HPLC method for determination of rofecoxib in human serum is presented. The method is based on pre-column derivatization of analyte to a phenanthrene derivative of the drug. Rofecoxib and the internal standard were extracted from serum using liquid–liquid extraction. Upon exposure to UV light, the drug was found to undergo a photocyclization reaction, giving a species with high absorbance. Validation of the method has been studied in the concentration range 10–500 ng ml^–1.     

Analysis of natural corticosteroids in adrenal extracts and in biological fluids by high-performance liquid chromatography

A liquid chromatographic procedure is described for the analysis of the principal natural corticosteroids in extracts of adrenal glands. Microparticulate silicic acid columns and gradients of methanol in chloroform are used: conditions are described for the quantitative analysis of the single principal steroidal components of adrenal extracts for pharmaceutical use and of adrenal extracts of rats. In the last case, the use of a 5-micron silica column with the appropriate gradient allows the determination of corticosterone and of 18-hydroxydeoxycorticosterone, which were identified by means of mass spectrometry on their eluates. A single analysis can be performed on the extract of 15 mg of rat adrenal tissue. For the last type of analysis, isocratic conditions on a 10-micron LiChrosorb Diol column are also described. The application of the gradient elution procedure to the analysis of steroidal compounds in human plasma is also described.     

Simultaneous determination of ampicillin, cefoperazone, and sulbactam in pharmaceutical formulations by HPLC with beta-cyclodextrin stationary phase

An accurate and reproducible method for the simultaneous determination of ampicillin (AMP), sulbactam (SUL), and cefoperazone (CFP) in pharmaceutical formulations by using HPLC with beta-CD stationary phase was developed. It involved the use of the added tetraethylammonium acetate (TEAA) reagent, pH, and methanol as the significant parameters to find the optimum separation condition. A high resolution and selectivity of analytes was obtained by running the mobile phase in methanol-5 mM TEAA buffer = 35:65 (v/v, pH 4.5) at 280 nm. The mean recoveries ranged from 96.6 to 103.3% for AMP in the synthetic mixture, 97.6 to 103.0% for SUL, and 97.0 to 104.0% for CFP. The low LOD (<1.8 microg/mL) and low CV (<0.9%) assured that this method was sensitive and reproducible. The assay of analytes in commercial products exhibited that it was convenient and reproducible for routine analyses of these components in sterilized H(2)O, saline, or 5% dextrose injection solutions.     

Determination of flavour components in natural vanilla extracts and synthetic flavourings by mixed micellar electrokinetic capillary chromatography

The development of a mixed micellar electrokinetic capillary chromatography (MECC) method for the qualitative and quantitative determination of key components, including vanillin, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, vanillic acid and 3-methoxybenzaldehyde, that contribute to vanilla flavour was investigated. The micellar phase consisted of sodium dodecyl sulfate (SDS) and sodium cholate (SC). The percent relative standard deviation (R.S.D.%) for migration time was <1 over six runs. The R.S.D.% for peak areas ranged between 0.85-1.96% over six runs. Peak efficiencies were excellent with theoretical plate numbers typically in the range of 130,000-200,000 per column (52 cm effective length). The limits of detection (LOD) were between 5-10 μg/ml. The quantitative data was verified by high performance liquid chromatography (HPLC) and gas chromatography (GC). The mixed MECC method was successfully applied to a number of natural vanilla extracts, nature identical extracts and synthetic flavourings.     

Development and validation of a HPLC method for the determination of voriconazole in pharmaceutical formulation using an experimental design

A rapid and sensitive RP-HPLC method with UV detection (260 nm) for routine analysis of voriconazole in a pharmaceutical formulation (Vfend^®) was developed. Chromatography was performed with mobile phase containing a mixture of acetonitrile and water (50:50, v/v) with flow rate was of 1.0 ml min⁻¹. Quantitation was accomplished with internal standard method. The procedure was validated for linearity (correlation coefficient = 0.9999), accuracy, robustness and intermediate precision. Experimental design was used for validation of robustness and intermediate precision. To test robustness, three factors were considered. Percentage of acetonitrile in mobile phase, flow rate and p^H; an increase in the flow rate results in a decrease of the drug found concentration, while the percentage of organic modifier and p^H have no important effect on the response. For intermediate precision measure the variables considered were: analyst, equipment and number of days. The R.S.D. value (0.45%, n = 24) indicated a good precision of the analytical method. The proposed method was simple, highly sensitive, precise and accurate and retention time less than 4 min indicating that the method is useful for routine quality control.     

Simultaneous determination of diethylene glycol and propylene glycol in pharmaceutical products by HPLC after precolumn derivatization with p-toluenesulfonyl isocyanate

A simple and reliable HPLC method was developed for the simultaneous quantitative analysis of diethylene glycol (DEG) and propylene glycol (PG) in pharmaceutical products by precolumn derivatization. The derivatization reagent p-toluenesulfonyl isocyanate (TSIC, 10 microL, 20% in ACN v/v) was added to 100 microL of the sample, and then 10 muL of water was added. The resulting derivatives were separated using a C(18)analytical column and a mobile phase composed of 0.01 M KH(2)PO(4)buffer (adjusted to pH 2.5 with phosphoric acid) and ACN (47:53 v/v) at 1 mL/min and 25 degrees C. For detection, UV light at 227 nm was used. The derivatization conditions including reaction time, temperature, and concentration of TSIC were optimized. The calibration curves were linear from 0.062 to 18.6 microg/mL (r(2)= 0.9999) and from 0.071 to 21.3 microg/mL (r(2) = 0.9999) for DEG and PG, respectively. The RSD values of intra- and interday assays were all below 4% for DEG and PG. The proposed method was then successfully applied to analyze two Armillarisin A injection samples and two spiked syrup samples.     

Validation of a novel HPLC sorbent material for the determination of ten quinolones in human and veterinary pharmaceutical formulations

A novel sorbent material of ultrapure silica gel provided with novel State of the Art Bonding- and Endcapping Technology commercially available under the name PerfectSil Target (250 x 4 mm, ODS-3, 5 microm, by MZ-Analysentechnik, Germany) was used and validated for the sensitive HPLC determination of ten quinolone antibiotics: enoxacin, ofloxacin, norfloxacin, ciprofloxacin, danofloxacin (DAN), enrofloxacin (ENR), sarafloxacin, oxolinic acid (OXO), nalidixic acid (NAL), and flumequine. The analytical column validation was performed in terms of separation efficiency, precision, and peak asymmetry. The separation was achieved at ambient temperature using a mobile phase of TFA (0.1%)-CH3OH-CH3CN delivered under the optimum gradient program, at a flow rate of 1.2 mU/min. Photodiode array detection was used and eluant was monitored at 275 nm. For the quantitative determination caffeine (7.5 ng/microL) was used as internal standard. The achieved LODs were 0.03 ng/microL per 50 microL injected volume for OXO, 0.1 ng/microL for DAN, ENR, and NAL, and 0.2 ng/microL for the remaining six studied quinolones. The method was validated in terms of interday (n = 6) and intraday (n = 5) precision and accuracy. The proposed method was successfully applied to the analysis of pharmaceutical formulations destined either for human or for veterinary use.