Voltammetric and subtractively normalized interfacial FTIR study of the adsorption and oxidation ofL(+)-ascorbic acid on Pt electrodes in acid medium: effect of Bi adatoms

1994 ◽  
Vol 90 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Miguel A. Climent ◽  
Antonio Rodes ◽  
Maria J. Valls ◽  
Juan M. Pérez ◽  
Juan M. Feliu ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Acid Medium ◽  
Medium Effect ◽  
Ftir Study ◽  
Pt Electrodes

Potentiometric Determination of Vitamin C in Highly Colored Products

1964 ◽  
Vol 47 (4) ◽  
pp. 754-755
Author(s):  
William S Hardesty
Keyword(s):  
Ascorbic Acid ◽  
Acetic Acid ◽  
Vitamin C ◽  
Acid Medium ◽  
Potentiometric Titration ◽  
Potentiometric Determination ◽  
Acetic Acid Medium ◽  
Commercial Products ◽  
Pt Electrodes

Abstract The method of Barakat and co-workers for determination of vitamin C in colored products has been modified for potentiometric use. The procedure is simple and rapid: An aliquot of sample containing 1—3 nig of ascorbic acid is titrated in a 3% acetic acid medium in the presence of KI with previously standardized 0.01% N-bromosuccinimide. The potentiometric titration uses two Pt electrodes with a polarizing current. Results were compared with the USP XVI method and the AOAC 2,6-dichlorophenol indophenol method. Recoveries, obtained from seven commercial products, four of which were vitamin C-enriched, ranged from 96 to 101%. The method also works well on drug mixtures containing ascorbic acid. It is recommended that the method be studied collaboratively.

scholarly journals Spectrophotometric determination of phosphorus in coal and coal ash using bismuth-phosphomobybdate complex

2003 ◽  
Vol 68 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Randjel Mihajlovic ◽  
Natasa Ignjatovic ◽  
Marija Todorovic ◽  
Ivanka Holclajtner-Antunovic ◽  
Vesna Kaljevic
Keyword(s):  
Aqueous Solution ◽  
Ascorbic Acid ◽  
Acid Medium ◽  
Spectrophotometric Method ◽  
Methyl Ketone ◽  
Coal Ash ◽  
Molar Absorptivity ◽  
Stable Complex ◽  
Tolerance Limits

A modified spectrophotometric method using the bismuth phosphomolybdate complex for the determination of phosphorus in coal and coal ash is suggested. Bismuth together with phosphate and molybdate forms a very stable complex in acid medium which turns blue ("molibdenum blue") by reduction with ascorbic acid. The apparent molar absorptivity of PBiMo is 1.66x104 dm3 mol-1cm-1 at 720 nm and 2.10x104 dm3 mol-1cm-1 at 670 nm isobutyl methyl ketone (MIBK). Interference caused by the ions present are within the tolerance limits (?2 %). Beer?s law is obeyed in the for concentration range to 0.6 ?g/mL (aqueous solution) and to 1.2 ?g/mL P (MIBK). The sensitivity of the proposed method is 0.0078 ?g/mL (aqueous solution) and 0.0066 ?g/mL (MIBK).

scholarly journals Sensitive Spectrophotometric Methods for the Determination of Ascorbic Acid

2008 ◽  
Vol 5 (1) ◽  
pp. 10-15 ◽  
Author(s):  
H. D. Revanasiddappa ◽  
M. A. Veena
Keyword(s):  
Ascorbic Acid ◽  
Acid Medium ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Spectrophotometric Methods ◽  
Maximum Absorbance ◽  
Hydrochloric Acid Medium ◽  
Subsequent Determination ◽  
Sulphuric Acid Medium

Two simple and sensitive spectrophotometric methods (A and B) have been described for the determination of ascorbic acid. Method A is based on the oxidation of ascorbic acid (AA) by known excess of Se(IV) in hydrochloric acid medium and subsequent determination of unreacted Se(IV) by reacting it with iodide in the same acid medium to liberate iodine, which react with starch to form a stable blue coloured iodine-starch complex, which shows maximum absorbance at 590 nm. Method B is based on the oxidation of ascorbic acid (AA) by known excess of Cr(VI) in sulphuric acid medium and the determination of unreacted Cr(VI) with diphenyl carbazide (DPC) under the same acidic medium to produce a stable red-violet coloured species, which shows a maximum absorbance at 550 nm. The reacted oxidants (in methods A and B) correspond to the AA content. The apparent molar absorptivity values are found to be 1.627×104and 1.641×104L mol-1cm-1for methods A and B, respectively. The proposed methods are simple, sensitive and suitable for the routine analysis of AA in pharmaceutical formulations and in real samples.

Dissolution of PuO2 in Hydrochloric Acid Medium—Effect of Reducing Agents

1989 ◽  
Vol 88 (3) ◽  
pp. 290-293 ◽  
Author(s):  
Mrs. Shakila Abdul Majeed ◽  
Thandangorai Ganapathi Srinivasan ◽  
Kanwal Nain Sabharwal
Keyword(s):  
Hydrochloric Acid ◽  
Acid Medium ◽  
Reducing Agents ◽  
Medium Effect ◽  
Hydrochloric Acid Medium

scholarly journals Single sweep polarographic determination of trace nitrite in ferrous and ascorbic acid medium.

1990 ◽  
Vol 6 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Jianwei Mo ◽  
Duan JIN ◽  
Jianhong PEI ◽  
Zaofan ZHAO
Keyword(s):  
Ascorbic Acid ◽  
Acid Medium ◽  
Polarographic Determination
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