Optosensor for Cinchona Alkaloids With C18 Silica Gel as a Substrate

Abstract

A flow-through optosensor for cinchona alkaloids with C18 silica gel as a substrate is proposed. The sensor is developed in conjunction with a flow-injection analysis system and is based on the retention of the cinchona alkaloids on a C18 column and the enhancement of their fluorescence. The analytical performance characteristics of the proposed sensor for the detection and quantification of these alkaloids were as follows: the detection limits of quinine, cinchonine, quinidine and cinchonidine were 2.3, 31.6, 2.3 and 31.6 ng ml-1, respectively, with relative standard deviations of 0.9% for quinine and quinidine (20 ng ml-1, n = 7) and 1.1% for cinchonine and cinchonidine (4.0 micrograms ml-1, n =7), respectively. Most of the common species did not interfere. The recommended method has been successfully tested for determination of quinine in pharmaceutical preparations and soft drinks.

Fast and Sensitive New High Performance Liquid Chromatography Laser Induced Fluorescence (HPLC-LIF) Method for Quinine. Comparative Study in Soft Drinks

“…Neither a preliminary liquid-liquid extraction [18] with a crystallization of quinine from soft drinks, [22] nor additional special solutions (H 2 SO 4 or Na 2 PO 4 ) added to the dilution of sample are necessary [15,21] in this first step before analysis. The present method use 1 mL of soft drink for the sample preparation.…”

“…[13] Several methods were proposed, mostly for the concrete determination of quinine in soft drinks. These techniques include atomic absorption spectrometry (indirect determination) with reversed flow injection system, [14] flow through sensor with fluorimetric transduction, [15] isotachophoresis with UV and conductivity detection, [16] 4th-order derivative spectrophotometric, [17] spectrophotometric, [18] fluorimetry, [19,20] plasticized poly(vinyl chloride) membrane electrode with direct potentiometry, [21] optosensor with C 18 silica gel as substrate in conjunction with a flow injection analysis system, [22] cyclic voltammetry, [23] and immunoassay. [24] In this paper a simple, rapid, and sensitive method was developed for the routine determination of quinine based on high performance liquid chromatography (HPLC) with LIF detection.…”

Recent Development in Optical Chemical Sensors Coupling with Flow Injection Analysis

“…A flow-through optosensor for cinchona alkaloids with C 18 silica gel as a substrate is proposed [73]. The sensor is developed in conjunction with a flow-injection analysis system and is based on the retention of the cinchona alkaloids on a C 18 column and the enhancement of their fluorescence.…”

Resolution of (+)-cinchonine and (−)-cinchonidine by phase-modulation fluorescence spectroscopy

“…Cinchonine and cinchonidine are Cinchona alkaloids and several methods have been described for the determination of these alkaloids either in crude drug composites, in body fluids or in pharmaceutical formulations [6][7][8]. In this paper, phase-modulation fluorescence spectroscopy has been applied to resolve mixtures of these diasteromeric compounds, and results obtained from two different approaches have been evaluated.…”