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Determination of losartan, telmisartan, and valsartan by direct injection of human urine into a column-switching liquid chromatographic system with fluorescence detection.

Abstract：

:Column-switching high-performance liquid chromatographic (HPLC) method has been developed and validated for quantification of losartan, telmisartan, and valsartan in human urine. Urine samples were diluted on the extraction mobile phase (1:4, v/v) and a volume of 20 microL of this mixture were directly injected onto the HPLC system. The analytes were extracted from the matrix using an on-line solid-phase extraction procedure involving a precolumn packed with 25 microm C(18) alkyl-diol support (ADS), and a solution 2% methanol in 5mM phosphate buffer (pH 3.8) at a flow-rate of 0.8 mL/min for isolation and preconcentration of losartan, telmisartan, and valsartan. The enriched analytes were back-flushed after, onto the analytical column with a mixture of 5mM phosphate buffer (pH 3.8)-acetonitrile-methanol (65:20:15, v/v/v) at a flow-rate of 3.0 mL/min and detected by fluorescence at 259 and 399 nm as excitation and emission wavelength respectively. The separation of losartan, telmisartan, and valsartan was achieved on a Chromolith RP-18e monolithic column. The method provides extraction recoveries from spiked urine samples greater than 93%. Intra-day and inter-day precision were generally acceptable; the intra-day-assay C.V. was <3.5 for all compounds and the inter-day-assay C.V. was < 3.7%. The estimated calibration range was 0.001-2.5 microg/mL(-1) with excellent coefficient of determination (>0.9981). The detection limits for losartan, telmisartan, and valsartan at a signal-to-noise ratio of 5:1 were 0.002, 0.0002 and 0.001 microg/mL(-1) when a sample volume of 20 microL was injected. The proposed method permitted the simultaneous determination of losartan, telmisartan, and valsartan in 8 min, with an adequate precision and sensitivity. However, the overlap of the sample cleanup step with the analysis increases the sampling frequency to 12 samples/h. The developed column-switching method was successfully applied for the determination of these analytes in human urine samples of patients submitted at ARA-IIs therapy.

journal_name

J Pharm Biomed Anal

journal_title

Journal of pharmaceutical and biomedical analysis

authors

del Rosario Brunetto M,Contreras Y,Clavijo S,Torres D,Delgado Y,Ovalles F,Ayala C,Gallignani M,Estela JM,Martin VC

doi

10.1016/j.jpba.2009.04.015

subject

Has Abstract

pub_date

2009-09-08 00:00:00

pages

194-9

issue

eissn

0731-7085

issn

1873-264X

pii

S0731-7085(09)00230-1

journal_volume

pub_type

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Determination of losartan, telmisartan, and valsartan by direct injection of human urine into a column-switching liquid chromatographic system with fluorescence detection.