Speciation analysis of inorganic tin by on-column complexation ion chromatography with inductively coupled plasma mass spectrometry and electrospray mass spectrometry

• ICP-MS and ESI-MS used as complementary techniques to identify Sn-DTPA complex.
• ESI-MS was used to confirm the formation of Sn-DTPA complex.
• Complexation and the separation of Sn complex performed on anion-exchange chromatography.
• Detection of [Sn(DTPA)]3− and [Sn(DTPA)]1− achieved by ICP-MS.
• The proposed method used for the determination of tin species in contaminated water.

Inductively coupled plasma-mass spectrometry (ICP-MS) and electrospray mass spectrometry (ESI-MS) were used as complementary methods to identify Sn-pentaacetic acid (DTPA) complex formation. ESI-MS was used to initially confirm the formation of [Sn(DTPA)]3− and [Sn(DTPA)]1− and their MS spectra suggest these tin complexes were stable in solution. On-column complexation of tin with DTPA and the separation of [Sn(DTPA)]3− and [Sn(DTPA)]1− was performed on anion-exchange chromatography with an mobile phase containing 20 mM NH4NO3 and 3 mM DTPA at pH 6.0, and the subsequent detection of [Sn(DTPA)]3− and [Sn(DTPA)]1− was achieved by ICP-MS. Linear plots were obtained in a concentration range of 1.0–1000 μg L−1 with detection limits ranging from 0.1 to 0.3 μg L−1. The developed procedure allows the simultaneous determination of [Sn(DTPA)]3− and [Sn(DTPA)]1− in less than 5 min with a RSD between 2.1 and 2.7%. The recoveries of [Sn(DTPA)]3− and [Sn(DTPA)]1− were found to be 96.8 and 99.4%, respectively, when the sample was spiked with 20 μg L−1 standard. Finally, the proposed procedure was used for the determination of tin species in contaminated water.