Distillation Method Using Miniature Apparatus for Determination of Total Cyanide by FIA

作者：Ozaki Shigeko^*; Moriuchi Ryosuke; Nakamura Eiko

来源：Bunseki Kagaku, 2012, 61(11): 953-957.

DOI：10.2116/bunsekikagaku.61.953

• total cyanide
• distillation
• leaching test
• soil
• FIA

Acid distillation is commonly carried out before the determination of total cyanide in aqueous samples to decompose metal-cyano complexes into HCN. We designed the miniature distillation apparatus, which consists of a 20 mL distillation tube, a 30 mL outer tube as a receiver, and an inner tube for air cooling. This apparatus (16 cm in width, 40 cm in height, and 27 cm in depth) was equivalent to about one-tenth of a standard distillation system in size. Sample and reagent solutions used were reduced to one-fiftieth of those used in the standard method. The proposed procedure is as follows: 5 mL of a sample, 0.2 mL of phosphoric acid (85 %), and 0.2 mL of EDTA (100 g L-1) were added to the distillation tube. Then, 2 mL of NaOH (20 g L-1) was added to the outer tube, in which the inner tube was covered. A maximum of 8 sets were heated by a dry block bath at 150 degrees C for 20 min. The CN- in the distillate was determined by FIA. Under the distillation conditions, potassium hexacyanoferrate as well as KCN was converted into HCN, whereas thiocyanate was not. The CN- was completely recovered from a KCN solution (0.05 mg L-1 as CN) in the presence of Fe(III) (%26lt;= 1000 mg L-1), Mn (II) (%26lt;= 100 mg L-1), and Zn(II) (%26lt;= 100 mg L-1). Satisfactory recoveries of CN- were found for a recovery test using the leaching solution from soils. The proposed distillation method is easier to operate, and reduces the distillation time, space, and consumption of chemicals and energy.

• 出版日期2012-11