HPLC-determination of nifedipine in plasma on normal phase |
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Authors: | H Mascher H Vergin |
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Institution: | (1) pharm-analyt Lab. GmbH, Wienerstr. 37, P.O. Box 4, A-2514 Traiskirchen/Vienna, Austria;(2) Heumann Pharma GmbH, Nürnberg, FRG |
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Abstract: | Summary For the determination of nifedipine in plasma a sensitive and selective method is required. The use of on-line pre-column enrichment, followed by reversed phase separation and UV-detection at 350 nm proved to be too susceptible. Therefore, detection was carried out after a post-column on-line reduction and photoreaction step using a fluorescence detector. Although this method proved to be extremely sensitive (limit of detection 0.1 ng/ml plasma) and selective, a number of problems cropped up caused by the reduction agent which finally prevented the procedure being used in routine analysis. As a consequence, the following method was developed. After liquid-liquid extraction of nifedipine a 1/3 of the extract was chromatographed on a normal phase (diOH) system and detected at 235 nm, because detection at 350 nm was not sensitive enough. This method has a limit of detection of 1 ng nifedipine/ml plasma and the calibration curve is linear up to 320 ng/ml. The recovery lies around 82% and the standard deviation for the range 6–320 ng/ml is less than 5%. So far about 2000 plasma samples have been analysed by this method. |
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Keywords: | Column liquid chromatography Nifedipine Normal phase Plasma Liquid-liquid extraction |
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