Sulfur isotope ratio (34S:32S) measurements in plant material by inductively coupled plasma mass spectrometry

Abstract

The³⁴S : ³²S isotope ratio in plant material was determined using measurements at m/z 48 and 50, corresponding to the ³²S¹⁶O⁺ and ³⁴S¹⁶O⁺ species, respectively, by inductively coupled plasma mass spectrometry (ICP-MS). The sulfur species in aqueous solutions and plant digests were separated and pre-concentrated in an anion-exchange resin (AG1-X8) column inserted in a flow system. The isotope ratio measurements for a sulfur solution containing 17 mg l^–1 was characterized by an RSD of <1%. Results for plant material enriched in ³⁴S were in agreement with those obtained by magnetic deflection mass spectrometry using electron ionization at the 95% confidence level. A sample throughput of 45 h^–1 was achieved.