Determination of mefloquine in blood, filter paper-absorbed blood and urine by 9-fluorenylmethyl chloroformate derivatization followed by liquid chromatography with fluorescence detection

Improved RP-HPLC determination of quinine in plasma and whole blood stored on filter paper

Analysis of quinine in plasma and whole blood samples dried on filter paper is described. Sample preparation involves liquid extraction of plasma and whole blood from the filter paper and subsequent solid-phase extraction using C8 Bond Elut cartridges. A reverse-phase liquid chromatography system with UV detection and fluorescence detection was used. The analytical characteristics of the method are reported, with a quantification limit of 0.1 microg mL(-1) and within an assay coefficient of variation of 5.6-8.4% in plasma and 6.5-12% in whole blood. Representative chromatograms are shown as a function of time for samples from human subjects after ingestion of a single 400-mg dose of quinine sulphate. Quinidine, dihydroquinine and metabolites are well separated from quinine with a resolution of above 1 (Rs>1).

Stereospecific determination of mefloquine in biological fluids by high-performance liquid chromatography

A sensitive stereoselective HPLC method was developed for determination of mefloquine (MFQ) enantiomers in plasma, urine and whole blood. The assay involved liquid-liquid extraction of MFQ from biological fluids with a mixture of hexane and isopropanol in the presence of sodium hydroxide and derivatization of the residue by (+)-(S)-naphthylethylisocyanate (NEIC) as chiral derivatizing reagent. Separation of the resulting diastereomers was performed on a silica normal-phase column using chloroform-hexane-methanol (25:74:1) as the mobile phase with a flow-rate of 1 ml/min. Using 200 microl of plasma or whole blood, the limit of determination was 0.2 microg/ml with UV detection for both enantiomers. The limit of determination in 500 microl of urine was 0.08 microg/ml with UV detection.

Determination of proguanil and metabolites in small sample volumes of whole blood stored on filter paper by high-performance liquid chromatography

A method is reported for the determination of proguanil and its two metabolites cycloguanil and 4-chlorophenylbiguanide in whole blood and plasma samples obtained by thumbprick and stored dry on filter paper. The sample preparation involves liquid extraction from the filter paper and subsequent solid-phase extraction using C8 Bond-Elut cartridges. Separation and quantification is by a previously reported ion-pairing high-performance liquid chromatographic system with ODS Hypersil as stationary phase and an 50:50 acetonitrile-pH 2 phosphate buffer mobile phase containing 200 mM sodium dodecylsulphate as ion-pairing agent. The analytical characteristics of the method are reported. Representative concentrations are shown as a function of time from a human subject after ingestion of a single 200-mg dose of proguanil hydrochloride. Typical ranges of concentration detected by the proposed method in human subjects were proguanil 12-900 ng/ml, cycloguanil 16-44 ng/ml and 4-chlorophenylbiguanide 1.5-10 ng/ml in whole blood.

UltramicroELISA para la deteccion de anticuerpos IgM al Mycobacterium leprae utilizando muestras de sangre seca

En este trabajo se establecen las condiciones optimas para la detección de anticuerpos IgM al glicolipido fenólico-I (GF-I) en muestras de sangre en papel de filtro utilizando el UltramicroELISA HANSEN y la tecnologia SUMA. Se estudiaron 300 donantes de sangre y 58 pacientes leprosos. Para estas dos poblaciones se compararon los resultados de muestras de sangre seca colectadas en papel de filtro SS-2992 con los de suero, y se obtuvo una correlación de 0.919 para donantes de sangre, 0.969 para pacientes y 0.954 para el total de las dos poblaciones. Se obtuvo una coincidencia de 98% en pacientes y 96% en donantes. En la población de pacientes la sensibilidad fue de 93% y la especificidad de 100% para las muestras de sangre seca evaluadas por el UMELISA HANSEN, con respecto a las muestras de suero analizadas por esta misma tecnica.

High-performance liquid chromatographic determination of (SR)- and (RS)-enantiomers of mefloquine in plasma and capillary blood sampled on paper after derivatization with (-)-1-(9-fluorenyl)ethyl chloroformate

A sensitive, stereoselective and rapid reversed-phase liquid chromatographic method for the determination of (SR)- and (RS)-mefloquine enantiomers in 100 microliters plasma and capillary blood collected on chromatographic paper is presented. The assay involves protein precipitation from plasma, liquid-liquid extraction of mefloquine from plasma, capillary blood with methyl tert.-butyl ether under alkaline conditions and derivatization of MQ with (-)-1-(9-fluorenyl)ethyl chloroformate. Liquid chromatographic separation of the diastereomers was performed using an C18 reversed-phase column with acetonitrile-water-acetic acid 82:18:0.07 (v/v/v) as the mobile phase, and a flow-rate of 1.0 ml/min. When using 100 microliters of plasma the limit of determination is 250 nmol/l with ultraviolet- and 10 nmol/l with fluorescence detection. The present method offers several advantages over those previously reported; very low limit of determination, small sample volume, sampling onto paper and use of an inexpensive standard achiral HPLC column. No racemization during the derivatization procedure or storage of the MQ enantiomers was found.

Improved column-switching liquid chromatographic method for the determination of the enantiomers of mefloquine

A liquid chromatographic method for the determination of the enantiomers of mefloquine has been improved. The chromatography involved two columns: an achiral cyanopropyl stationary phase for the quantification of (+/-)-mefloquine and a chiral naphthyl-urea stationary phase for the determination of the enantiomeric ratio. Compared with the previous method, which needed two detectors, this one used one detector-integrator to which the two columns are connected alternately by an automated column-switching system. The method is suitable for the quantification (0.05 microgram/ml) of mefloquine and the determination of enantiomeric ratios from 500-microliters plasma samples with ultraviolet detection.

High-performance liquid chromatographic method for the simultaneous determination of mefloquine and its carboxylic metabolite in 100-microliters capillary blood samples dried on paper

A reversed-phase high-performance liquid chromatographic method is described for the analysis of mefloquine and its carboxylic metabolite in 100-microliters capillary blood spots dried on chromatographic paper. Each spot was cut into small pieces, and mefloquine and its metabolite were eluted with an ammonia-water solution (10:90, v/v). The compounds were extracted simultaneously after alkalization at pH 9.5 using tetrabutylammonium as ion-pairing agent and then separated on a C18 column with ultraviolet detection at 227 nm. The recovery of the drugs from spiked blood applied to paper and dried was 70-80%, and the inter-assay precision at 1.0-5.0 mumol/l (therapeutic range) was less than 10%. The correlation between extractions from venous whole blood and capillary blood applied to chromatographic paper was more than 0.94. The analytes were stable in dried blood spots for at least fifty days at -20 degrees C. The decrease of concentration was less than 10%, when the paper was stored at 37 degrees C for fifty days. The assay is reliable and easy to use for therapeutic monitoring of mefloquine with a lower limit of determination of 0.3-0.5 mumol/l.