摘要：A rapid, simple, and accurate colorimetric method with hematein reagent was established for the determination of a trace of tin in canned juice. The sample was prepared by digesting 1.0-5.0 ml of canned juice with a mixture of sulfuric acid-nitric acid. To 0.2-1.4 ml of the sample, 0.1 ml of 10% tartaric acid and one drop of 1% phenolphthalein were added. After neutralization with alkali, 2 ml of 20% sulfuric acid and 2 ml of 1% acacia were further added. This mixture was diluted to 15 ml with water, and 5 ml of 0.3% hematein reagent was added and mixed well. This mixture was allowed to stand for 40 min at room temperature, and then was further diluted to 40 ml with 0.5% sulfuric acid. Absorbance of this solution was determined at 560 nm against the reagent blank. Under the above condition, tin content in two kinds of canned juice was determined with a recovery of 94-111% and coefficient of variation of about 5%. A more rapid method by the addition of hematein reagent directly without digestion of the sample juice was examined, and results obtained with canned orange and apple juice were very satisfactory, with a recovery of 96-109% and coefficient of variation of about 4%. The time required for determination of tin by this method was about 1 hr for 10 samples.
关键词：tin determination;hematein;oxidized hematoxylin;colorimetry;canned juice
