Determination of Tin in Canned Foods by Inductively Coupled Plasma-Mass Spectrometry

Most foods contain very low concentrations of tin, usually below 10 mg/kg, although canned foods may contain higher concentrations as a result of the slow dissolution of the tin coating used on the inside of some food cans to protect the steel body of the can from corrosion. An inductively coupled plasma-mass spectrometry (ICP-MS) method following microwave digestion was developed and evaluated to determine levels of dissolved tin in canned foods. Accuracy of the method was tested by analyzing analytical standards containing tin at 2 levels (0.5 and 5 ppm). Amounts of tin found for the 0.5 and 5 ppm standards were 0.505 and 5.12 ppm, while repeatability relative standard deviations (RSD) were 2.42 and 1.87%, respectively. Recoveries of tin from spiked products with two levels of tin ranged from 91.3 to 105.2%. The detection limit for tin standard solution was about 0.01 ppb. The developed method was used to determine levels of tin in several kinds of canned foods from the present market. Samples of canned pineapple, mandarins, fruit cocktail, carrots, mushrooms, peas, beans, corn, peeled tomatoes, and tuna were evaluated. The relationships between tin concentrations and time periods after opening were studied.