A Collaborative Study on the Determination of Lead in Canned Vegetable Juice by the Polarographic Method

Abstract

A collaborative study was conducted on the polarographic determination of lead in canned vegetable juice. The ash obtained by dry-ashing a sample at 450°C was dissolved in 6N hydrochloric acid and the pH was adjusted to 6.4-6.6 with ammonium citrate buffer solution and ammonia water. This solution was treated on a Dowex A-1 resin column. This procedure completely removed tin, which interfered with lead determination. Lead was eluted from the column with dilute nitric acid, concentrated, and the residue was dissolved in electrolyte for polarography. The interlaboratory coefficients of variation by this method were 8.0 to 10.9%. If the treatment for the removal of tin was omitted, on the other hand, the analytical data showed much greater variation. It thus appears that the removal of tin from test solutions is essential for the reliable determination of lead in canned foods by polarography.