Rapid Determination for Borax in Soymilk by Improved Azomethine H Acid Method

[Objective]To establish a new method for rapid determination of borax in soymilk. [Method]The commercially available soybean milk were mercerized,carbided,ashed,and then the ash was dissolved with 5 ml 5% HCl,borax were converted into the borate ion. With azomethine H acid as chromogenic agent,the absorbance value was determined at wavelength 420 nm. [Result] The results showed that the linearity is good when boric acid concentration in the sample is 0- 0. 500 mg/ml. The linear correlation coefficient is 0. 999 1,the recovery is 97. 04%- 99. 58%,and the RSD is 1. 53%- 3. 69%,the lowest detection limit concentration is 1. 83 mg/kg. Compared with curcumin spectrophotometry,the difference was not significant (t = 1. 800,P 0. 05). [Conclusion] The law required experimental equipment is simple,avoids the tedious enrichment step,saves a large amount of ethanol,the sensitivity and accuracy can meet the requirement analysis, and is applicable to large quantities of soy milk in borax detection.