4th order derivative spectrophotometric determination of quinine in soft drinks

Castro, J. C. García; Sánchez, M. J.; Delgado, Miguel Ángel Rodríguez; Dı́az-Romero, Carlos

doi:10.1007/bf01245110

Cited by 11 publications

(1 citation statement)

References 6 publications

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“…In terms of analytical chemistry, there have been developed many analytical methods for the determination of QN in several samples, including biochemical and food samples. These methods are mainly instrumental, including batch spectrometry [15], atomic absorption spectroscopy (AAS) [16], capillary electrophoresis [17,18], electrochemistry [19][20][21], flow injection analysis (FIA) [22,23], chemiluminescence [24][25][26], liquid chromatography [27][28][29][30], mass spectrometry [31], and fluorescence [32,33].…”

Section: Introductionmentioning

confidence: 99%

A Novel Equipment-Free Paper-Based Fluorometric Method for the Analytical Determination of Quinine in Soft Drink Samples

Tsaftari,

Tarara,

Tzanavaras

et al. 2023

Sensors

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A simple, equipment-free, direct fluorometric method, employing paper-based analytical devices (PADs) as sensors, for the selective determination of quinine (QN) is described herein. The suggested analytical method exploits the fluorescence emission of QN without any chemical reaction after the appropriate pH adjustment with nitric acid, at room temperature, on the surface of a paper device with the application of a UV lamp at 365 nm. The devices crafted had a low cost and were manufactured with chromatographic paper and wax barriers, and the analytical protocol followed was extremely easy for the analyst and required no laboratory instrumentation. According to the methodology, the user must place the sample on the detection area of the paper and read with a smartphone the fluorescence emitted by the QN molecules. Many chemical parameters were optimized, and a study of interfering ions present in soft drink samples was carried out. Additionally, the chemical stability of these paper devices was considered in various maintenance conditions with good results. The detection limit calculated as 3.3 S/N was 3.6 mg L−1, and the precision of the method was satisfactory, being from 3.1% (intra-day) to 8.8% (inter-day). Soft drink samples were successfully analyzed and compared with a fluorescence method.

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Section: Introductionmentioning

confidence: 99%

A Novel Equipment-Free Paper-Based Fluorometric Method for the Analytical Determination of Quinine in Soft Drink Samples

Tsaftari,

Tarara,

Tzanavaras

et al. 2023

Sensors

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Energy‐Dispersive and X‐Ray Photoelectron Spectroscopy and Electron Microscopy of New Quininium‐Plastic Membrane Electrodes

2007

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New quininium (Qn) plastic membrane electrodes of the conventional type were constructed and characterized. They are based on incorporation of Qn-reineckate (QnRn) ion-pair, Qn-phosphotungstate (Qn3-PT), or Qn-phosphomolybdate (Qn3PM) ion associate into a poly(vinyl chloride) membrane. The electrodes are selective for Qn and have been successfully used for the determination of Qn2SO4 in pharmaceutical tablets. Nevertheless, they showed, as almost all other ion-selective electrodes, limited life times. Energy dispersive- (EDS) and X-ray photoelectron spectroscopy (XPS), as well as electron microscopy were applied to investigate the cause of this limitation in the life times of the electrodes. The results indicated that the electrodes lose their activity after prolonged soaking as a result of leaching of the ion exchanger from the membranes into the test solution in addition to deformation at the surface of the expired electrode.

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Flow‐Through Assay of Quinine Using Solid Contact Potentiometric Sensors Based on Molecularly Imprinted Polymers

Kamel

Sayour²

2009

Electroanalysis

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Miniaturized potentiometric membrane sensors for quinine incorporated with molecular imprinted polymer (MIP) were synthesized and implemented. Planar PVC based polymeric membrane sensors containing quinine-methacrylic and/or acrylic acid-ethylene glycol methacrylate were dispensed into anisotropically etched wells on polyimide wafers. The determination of quinine was carried out in acidic solution at pH 6, where positively charged species predominated prevalently. The suggested miniaturized planner sensors exhibited marked selectivity, sensitivity, longterm stability and reproducibility. At their optimum conditions, the sensors displayed wide concentration ranges of 4.0 Â 10with slopes of about 61.3 -55.7 mV decade À1 ; respectively. Sensors exhibit detection limits of 1.2 Â 10 À6 and 8.2 Â 10 À6 mol L À1 upon the use of methacrylic and acrylic acid monomers in the imprinted polymer, respectively. Validation of the assay method according to the quality assurance standards (range, within-day repeatability, between-day variability, standard deviation, accuracy, and good performance characteristics) which could assure good reliable novel sensors for quinine estimation was justified. Application of the proposed flow-through assay method for routine determination of quinine in soft drinks was assayed and the results compared favorably with data obtained by the standard fluorimetric method.

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4th order derivative spectrophotometric determination of quinine in soft drinks

Abstract: A method is developed for the 4rd order derivative spectrophotometric determination of down to 1-6/tg/ml of quinine. This method has been applied to its determination in soft drinks. Comparison are made between this method and a spectrofluorimetric method.

Cited by 11 publications

References 6 publications

A Novel Equipment-Free Paper-Based Fluorometric Method for the Analytical Determination of Quinine in Soft Drink Samples

A Novel Equipment-Free Paper-Based Fluorometric Method for the Analytical Determination of Quinine in Soft Drink Samples

Energy‐Dispersive and X‐Ray Photoelectron Spectroscopy and Electron Microscopy of New Quininium‐Plastic Membrane Electrodes

Flow‐Through Assay of Quinine Using Solid Contact Potentiometric Sensors Based on Molecularly Imprinted Polymers

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