Determination of Tin in Canned Foods by Atomic Absorption Spectrometry

Atomic absorption spectrometry is a powerful technique for determination of tin in canned foods. Homogenous samples of syrup and solid parts were digested by means of microwave digestion system MLS 1200 MEGA where hydrochloric and nitric acid were used as reagents. The measurements were carried out using a Perkin-Elmer AAnalyst 700 atomic absorption spectrometer. Detection limit was 4 mg/kg in nitrous oxide and acetylene flame. There were analysed 222 samples of 26 various kinds of canned fruit (e.g. pineapple, peach, mandarin), vegetables (e.g. bean, mushroom, tomato) and meat (sea products) in this work. The analytical results indicated tin total concentrations from under 4 mg/kg to 353 mg/kg. Different concentrations of tin between syrup and fruit were observed. The concentration of tin was higher in solid parts than in syrup. Relationship between the concentration and time period after opening was studied. The corrosion of the tinplate surface was accelerated by air and the amount of dissolved tin was significantly increasing in syrup as well as fruit when cans were opened and stored for two days at 6 degrees C.