Tin cans - a possible source of contamination of canned food

Food preservation Canning food is a good method of preservation which uses no chemical preservatives and is therefore widely used. Usually cans consist of tin plate which is tin coated steel. Tin is necessary to prevent iron from being corroded by the canned food. Unfortunately tin itself can slowly transfer into the food. The amount of tin taken up by the canned food is affected by many factors. Tin may cause stomach upsets and irritates the digestive tract of sensitive people when present in high concentrations. Fortunately there are no long-term effects due to normal intakes from tin in the food even if it is present in higher levels. An organic compound can be used to line the cans. These fully lacquered cans strongly reduce the levels of tin as long as this protective layer remains undamaged. Nevertheless a new problem arises due to the bisphenol-A which is contained in the lacquer paint and has a potential to interact (endocrine disrupter) with our hormone system.

Voltammetric analysis of tin Differential pulse anodic stripping voltammetry (DPASV) in combination with a hanging mercury drop electrode (HMDE) is an analysis method for determining the concentration of tin in canned food. Prior to the analysis the canned food has to be digested by means of a mixture of concentrated mineral acids. Lead, which was used with tin until lately as a solder (also for cans), can also be determined with the described method from Metrohm. There are a variety of methods described which allow a successful determination of lead even in presence of other metal ions as thallium or cadmium. A specification between Sn(II) and Sn(IV) is also possible. The anodic stripping voltammetry can be carried out on a MVA-2 system. The heart of this system is a 797 VA Computrace enriched with the unbeatable Dosino technique for liquid handling. For your convenience, the methods for the tin and lead determination are already implemented in Metrohm's 797 VA Computrace. Just press the button and start measuring.

Product information MVA-2 system intended for partly automated routine analysis and consisting of the 797 VA Computrace and two 800 Dosinos. MVA-2 Options MVA-3 system for fully automated analysis of small series of samples consisting of the 797 VA Computrace, a 813 Compact Autosampler, two 800 Dosinos, a 731 Relay Box and two 772 Pump Units MVA-3 Send me product information!

Get more information Order our free Monograph Practical Voltammetry (8.757.500X) in English or German. Find more application details in our Application Bulletin 176 (Info Center) Applications for Voltammetry and Polarography Overview of Metrohm VA Instruments

Tips Automation: Up to 18 samples are easily processed fully automatically by the MVA-3 system. Sample preparation: How digestion is done Validation: For the Validation of Metrohm VA instruments using Standard Operating Procedures see our Application Bulletin 276 (Info Center).