US EPA

4186152 

Journal Article 

A new simple and accurate turbidimetric method for determination of ascorbic acid in pharmaceuticals and fruits 

Farajzadeh, MA; Nagizadeh, S 

2002 

Yes 

Journal of the Chinese Chemical Society
ISSN: 0009-4536 

49 

5 

949-956 

10.1002/jccs.200200134 

WOS:000178967200038 

An accurate, simple, solvent free and inexpensive turbidimetric method is presented for the determination of ascorbic acid in pharmaceutical preparations and fruits. It needs no special reagents or precautions. In this method HgCl2 oxidizes ascorbic acid in citrate buffer at a pH of about 4 and produced Hg2Cl2 precipitate as monitored by turbidance measurements. The procedure is very simple and the experimental conditions such as temperature, ionic strength, stirring and time are not critical. High sensitivity and selectivity are two other advantages of this method. Linear dynamic range of the calibration curve is between 3-120 mug/mL with limit of detection (LOD) 1 mug/mL, which allows the ascorbic acid contents of most fruits and vegetables to be analyzed. On the other hand, the interference studies show that common compounds in real samples and colored substances have no considerable effect on the determination. Only filtration of some samples is necessary and other treatments, which are performed prior to determination of ascorbic acid by other analytical methods, are eliminated. Finally, ascorbic acid concentration in different samples is determined by the proposed method and obtained results are compared with the results of the official 2,6-dichlorophenolindophenol or iodimetric methods and a good agreement is obtained. This method is very sensitive in comparison with iodimetry and is very fast relative to the 2,6-dichlorophenolindophenol method. 

ascorbic acid; turbidimetry; pharmaceuticals; fruit juices