Determination of tin in the ng g−1 range differential pulse polarography

A sensitive determination method of tin by differential pulse polarography is described. Addition of tropolone to acetate supporting electrolyte at about pH 4.7 provides a 30-fold signal enhancement, giving a sensitivity comparable to that obtained in anodic stripping voltammetry, but without the need for enrichment by pre-electrolysis. The response is linear over more than three orders of magnitude (1 ng ml^?1?5 μg ml^?1 Sn), allowing measurements within a wide concentration range without changes in sample preparation or measuring conditions. Large amuonts of Ti, W, Cr or Mo interfere, but can be removed completely by pre-separation of tin based on extraction with tropolone/toluene and back-extraction into the supporting electrolyte. Results for tin in water and fruit juice are consistent with those obtained by other techniques.