Liquid chromatographic determination of selenium in vegetables and tea leaves as 2,1,3-benzoselenasiazole

Derivatization and liquid chromatographic determination of selenium in vege tables and tea leaves have been performed. The samples were digested with ( i) nitric acid or (ii) sulfuric acid - nitic acid - hydrogen peroxide mixtu re, followed by treatment with hydrochloric acid to reduce selenium(VI) to (IV). The resulting solution was treated with 1,2-diaminobenzene, at pH 1- 2 and the product, 2,1,3-benzoselenadiazole was extracted with toluene. RP- HPLC analysis was carried out on a ODS Lichrosorb C-18, 5 mum, (150 x 4 mm, i.d.) with methanol - water (1: 1) as mobile phase, and UV detection at 33 2 nm. The detector response was linear in the range of 0 - 15 mug / ml with regression coefficient 0. 998. The limit of detection was found to be 0.2 mug / 10 muL injection. Results shows the level of selenium in vegetables a nd tea leaves to be in the range of 0.11 to 1.75 and 0.52 to 1.08 mug / g, respectively. The coefficient of variation was within 5 %.