Determination of Cyanide and Volatile Phenol in Almond by Continuous Flow Injection Spectrophotometry

A method for simultaneous determination of cyanide and volatile phenol in almond by continuous flow injection spectrophotometry was proposed. The almond sample (2.00 g) was whirled for 1 min and soaked for 10 min in 25 mL of 0.05 mol·L^-1 sulfuric acid solution. After hydrolyzed to release cyanide glycosides in the sample, 2 g·L^-1 sodium hydroxide solution was added to fix the test substance and make its volume up to 50 mL. The supernatant was taken and passed through 0.45 μm filter membrane, in which cyanide and volatile phenol was determined by continuous flow injection spectrophotometry under optimized experimental conditions. As shown by the results, linear relationships between values of the corresponding peak height and mass concentration of cyanide and volatile phenol were found in the range of 0.002-0.200 mg·L^-1, with detection limits of 0.005 mg·kg^-1 for cyanide, 0.017 5 mg·kg^-1 for volatile phenol, respectively. The 3 samples were taken and determined 6 times repeatedly for each sample, with RSDs (n=6) of the determined values less than 2.0%. Test for recovery was made on the actual samples by the standard addition method, giving results in the range of 97.6%-105%. This method was applied to analysis of 10 almond samples, and the detection amounts of cyanide were 10.6-56.4 mg·kg^-1, with an average value of 32.3 mg·kg^-1, while the detection amounts of volatile phenol were 14.7-54.8 mg·kg^-1, with an average value of 31.9 mg·kg^-1. In this method, sulfuric acid solution was used to hydrolyze the cyanide glycoside in the sample and then it was fixed with alkaline solution, which could solve the problem of low results obtained by direct extraction with alkaline solution.