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Open AccessArticle

Determination of Food Oxalates Using Silica–Titania Xerogel Modified with Eriochrome Cyanine R

Analytical Chemistry Division, Chemistry Department, Lomonosov Moscow State University, Moscow 119234, Russia
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Sensors 2018, 18(3), 864; https://doi.org/10.3390/s18030864
Received: 29 December 2017 / Revised: 2 March 2018 / Accepted: 12 March 2018 / Published: 15 March 2018
(This article belongs to the Special Issue Spectroscopy Based Sensors)
The interaction of silica–titania xerogel with triphenylmethane dyes (pyrocatechol violet, chrome azurol S, eriochrome cyanine R) has been investigated to create a new sensor material for solid phase spectrophotometric determination of food oxalates. The complex forming reaction between xerogel incorporated titanium(IV) and triphenylmethane dyes has been studied; half-reaction periods, complex composition, equilibrium constants, and xerogel sorption capacity have been calculated for each dye. Eriochrome cyanine R (ECR) is characterized by the shortest half-reaction period, the smallest equilibrium constant, and the greatest capacity; it has been chosen for the sensor material construction because titanium(IV)-ECR complex is formed faster and can be destroyed easier than other studied complexes. The interaction of this sensor material with oxalates has been described: the presence of oxalates causes sensor material discoloration and the absorbance is used as analytical signal. The analytical range is 35–900 mg/L (LOD 10.5 mg/L, n = 7). High concentrations of interfering inorganic anions, organic acids, and sucrose did not affect oxalate determination. Proposed solid phase spectrophotometric procedure has been successfully applied for the determination of oxalates in food samples (sorrel, spinach, parsley, ginger, and black pepper) and the results are in good agreement with HPLC oxalate determination. View Full-Text
Keywords: oxalate determination; silica–titania xerogel; triphenylmethane dyes; food oxalates; solid phase spectrophotometry oxalate determination; silica–titania xerogel; triphenylmethane dyes; food oxalates; solid phase spectrophotometry
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Morosanova, M.A.; Samodelov, Z.V.; Morosanova, E.I. Determination of Food Oxalates Using Silica–Titania Xerogel Modified with Eriochrome Cyanine R. Sensors 2018, 18, 864.

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