Flow Injection Analysis of Carboxylic Acid Drugs Using Cationic Dyes and On-Line Ion-Pair Extraction

Abstract

Journal of Liquid ChromatographyPublication details, including instructions for authors and subscription information:ABSTRACT A flow injection system containing an on-line ion-pair extractor has been designed for the analysis of carboxylic acid drugs using either spectrophotometric detection with gentian violet as counterion or fluorescence detection with acridine orange. Salicylic acid, valproic acid, and ibuprofen were selected as model drugs. phosphate buffer-absolute methanol was pumped through the system at 1 ml/min. A chloroform solution of the cationic dye was pumped into the mobile phase at 1.25 ml/min and the chloroform layer containing the dye-drug ion-pair separated prior to detection. Peak height and absorbance were linear €or salicylic acid, valproic acid, and ibuprofen in the 0.5-10, 5-50, and 1-10 pg/ml ranges, respectively. Peak height and fluorescence were linear for salicylic acid, valproic acid, and ibuprofen in the 0.13-5, 2.5-50, and 0.5-20 ug/ml ranges, respectively. Accuracy and precision for the spectrophotometric assays were in the 2-6% and 3.3-6.6% ranges, respectively, and in the 0.3-4% and 1.3-5.4% ranges, respectively, for the fluorescence assays. Peak height and absorbance were also shown to be linear in the A mobile phase of 9O:lO aqueous pH 7 3353 Copyright 0 1988 by Marcel Dekker, Inc. Downloaded by [University of Calgary] at 02:40 06 February 2015 3354 STEWART, LANG, AND HONIGBERG16-500 pg/ml range for prostaglandin PGF precision of 1-3% and 5 4 % . respectively?afor spiked samples.Commercial dosage forms containing valproic acid and ibuprofen were assayed by the spectrophotometric assay and found to be within acceptable USP limits. Spiked ibuprofen samples at the 5 and 10 pg/ml level were assayed using an octadecylsilane column inserted into the flow injection system. One to two percent accuracy and 2.5-5% precision were obtained for the drug using the FIA-column system. with accuracy and

State of the art in on‐line techniques coupled to flow injection analysis FIA/on‐line‐ a critical review

“…Metals in the effluent were monitored spectrometrically using a colour-forming reaction with photocatechnic acid. Stewart et al [69] designed an on-line ionpair extraction for carboxylic acid analysis by spectrophotometric detection.…”