Colourimetric solid-phase extraction coupled with fibre optic reflectance spectroscopy for determination of ascorbic acid in pharmaceutical formulations

2011 ◽  
Vol 4 (6) ◽  
pp. 493-499 ◽  
Author(s):  
Hayati Filik ◽  
Duygu Aksu ◽  
Derya Giray ◽  
Reşat Apak
Keyword(s):  
Ascorbic Acid ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Pharmaceutical Formulations ◽  
Reflectance Spectroscopy ◽  
Phase Extraction ◽  
Fibre Optic

scholarly journals Solid-Phase Extraction Cleanup for Determining Ascorbic Acid and Dehydroascorbic Acid by Titration with 2,6-Dichlorophenolindophenol

1996 ◽  
Vol 79 (5) ◽  
pp. 1236-1243 ◽  
Author(s):  
Krishna K Verma ◽  
Archana Jain ◽  
Bhushan Sahasrabuddhey ◽  
Kalpana Gupta ◽  
Sanjeev Mishra
Keyword(s):  
Ascorbic Acid ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Dehydroascorbic Acid ◽  
Original Method ◽  
Phase Extraction ◽  
Fruit And Vegetable Juices ◽  
Coloring Matter ◽  
Sulfhydryl Compounds

Abstract Ascorbic acid is frequently determined by titration with 2,6-dichlorophenolindophenol. The determination is rapid, but the method is neither specific for ascorbic acid nor very sensitive. The coloring matter in the assay solution interferes with the visual endpoint, and iron(ll), copper(l), sulfite, and sulfhydryl substances such as cysteine and glutathione interfere with the color reaction. Sample cleanup by solid-phase extraction with C18 bonded silica was developed to remove the coloring matter. Extraction sorbent impregnated with 2,2′-bipyridyl, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and Jv-ethylmaleimide removes Fe(ll), Cu(l), and sulfhydryl compounds, respectively. The procedure was applied to highly colored multivitamin pharmaceuticals, soft drinks, and fruit and vegetable juices. In contrast to the results from the original method, which is not applicable to such samples, the results obtained by the method incorporating cleanup were accurate and selective for ascorbic acid. The sample cleanup also permitted determination of dehydroascorbic acid by reducing it to ascorbic acid with cysteine and titrating the ascorbic acid formed with indophenol. As little as 3 μg ascorbic acid was determined by the method incorporating cleanup.

Direct determination of sitagliptin in pharmaceutical formulations and its determination in urine after solid-phase extraction by spectrofluorimetry

Luminescence ◽  
2012 ◽  
Vol 28 (6) ◽  
pp. 873-878 ◽  
Author(s):  
Taiza de Paula e Mancilha ◽  
Carlos Eduardo Rodrigues de Paula ◽  
Ricardo J. Cassella ◽  
Wagner F. Pacheco
Keyword(s):  
Solid Phase Extraction ◽  
Solid Phase ◽  
Direct Determination ◽  
Pharmaceutical Formulations ◽  
Phase Extraction
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