Development of a <scp>Matrix‐Matched</scp> Barite Reference Material ( <scp>NWU‐Brt</scp> ) for Calibration of <i>In Situ</i> S Isotope Measurements by Laser Ablation <scp>Multi‐Collector</scp> Inductively Coupled <scp>Plasma‐Mass</scp> Spectrometry
Nan Lv, Zhian Bao, Xiaojuan Nie, Kaiyun Chen, Yan Zhang, Honglin Yuan
Abstract
A new matrix‐matched reference material (NWU‐Brt) with sulfur isotope ratios resembling those of natural barites has been developed for in situ S isotope measurements by laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (LA‐MC‐ICP‐MS). A 100 g quantity of natural barite crystal was milled to ultra‐fine particles and sintered to a solid block using a fast hot‐pressing sintering technique (FHPS). We report δ 34 S ratios determined by isotope ratio mass spectrometry (IRMS), solution nebuliser multi‐collector inductively coupled plasma‐mass spectrometry (SN‐MC‐ICP‐MS) and LA‐MC‐ICP‐MS, involving up to six participating laboratories. The homogeneity of δ 34 S ratios of the synthesised barite was tested by LA‐MC‐ICP‐MS with an analytical spot size of 53 μm. The LA‐MC‐ICP‐MS results show that NWU‐Brt demonstrates a satisfactory homogeneous composition and is an appropriate material for calibrating δ 34 S ratios in barite. IRMS and SN‐MC‐ICP‐MS produced mean δ 34 S values of +14.17 ± 0.42‰ (2 s ) and +14.27 ± 0.23‰ (2 s ), respectively. The results of LA‐MC‐ICP‐MS analyses are consistent with the IRMS and SN‐MC‐ICP‐MS ratios within uncertainty. Overall, our results confirm the suitability of NWU‐Brt for the calibration of δ 34 S ratios in barite using LA‐MC‐ICP‐MS.