Identification of Sb(V) Complexes in Biological and Food Matrixes and Their Stibine Formation Efficiency during Hydride Generation with ICPMS Detection

Several studies have described the synthetic preparation of Sb(V) complexes with organic ligands, but only recently was such a complex identified to exist in beverages stored in PET containers. In the present study, we have investigated by using HPLC-ICPMS and HPLC-ES-MS(/MS), the formation of Sb(V) complexes in various biological (urine) and food matrixes (yoghurt and juice) spiked with noncomplexed inorganic Sb(V). Our results show that Sb(V) complex formation is matrix dependent and that several Sb(V) complexes form to a considerable extent in these matrixes. The results also suggest that the existence of Sb(V) complexes in natural samples may have previously been overlooked due to analytical method limitations, mainly chromatographic, but also detection limitations when hydride generation is used. To overcome some of these limitations, we have developed chromatographic methods suitable for preserving Sb-organic ligand complexes during their separation. When applying this mild nondestructive chromatographic method, we were able to identify novel Sb complexes in yoghurt spiked with inorganic Sb(V), i.e., 1:1 Sb(V)-citrate, 1:1 Sb(V)-lactate, 1:2 Sb(V)-lactate, and other Sb(V)-lactate complexes. This is the first characterization of Sb(V)-lactate complexes. Detailed studies on the hydride generation (HG) efficiency of Sb(V) complexes showed that Sb(V) complexes of high stability, such as Sb(V)-citrate, Sb(V)-(adenosine)(n) and Sb(V)-(lactate)(n) (n = 1 or 2), are nondetectable by HG-ICPMS. Furthermore, Sb(V) complexes formed in natural biological and food matrixes were only partly detectable by HG-ICPMS, confirming limitations of analytical methods based on HG volatilization and subsequent stibine detection in natural samples containing complexing ligands with affinity toward Sb(V).