Purification of Mg from extremely low-Mg felsic rocks for isotopic ratio determination by MC-ICP-MS

Abstract

Magnesium isotopes are powerful tracer of various geological processes. The high precision determination of Mg isotopes has however been hampered by difficulties in purifying Mg from extremely low-Mg rocks due...

Accurate Measurement Of Mg Isotopes In Twenty-Four Reference Materials By MC-ICP-MS With A Highly Efficient Optimized Method

“…Mg isotopic fractionation is known to occur on different instruments owing to mass bias caused by acid molarity mismatch. [19][20][21] To verify the effect of Mg concentration mismatch on Mg isotope measurements, a series of 0.5 μg g -1 GSB-Mg solutions with different acid molarities (0.5% -6% HNO3) were measured using MC-ICP-MS using GSB-Mg (0.5 μg g -1 ) in 2% HNO3 as the bracketing standard. The difference in the acid molarities of the standards and samples resulted in an Mg isotope offset of approximately 0.5‰ (Fig.…”

“…20,21 The δ 26 Mg values of rhyolite RGM-2, JR-1, JR-3, and GSR-11 were -0.14 ± 0.04‰ (2 SD, n = 6), -0.19 ± 0.05‰ (2 SD, n = 3), -0.10 ± 0.05‰ (2 SD, n = 3), and -0.53 ± 0.10‰ (2 SD, n = 3), respectively and they were identical to published values within 2 SD uncertainties. 19,20,32,37 The δ 26 Mg value of AGV-2 was -0.12 ± 0.07‰ (2 SD, n = 3), and the mean δ 26 Mg values of basalt BCR-2 and BHVO-2 were -0.19 ± 0.08‰ (2 SD, n = 6) and -0.20 ± 0.06‰ (2 SD, n = 6), respectively. The δ 26 Mg values of BCR-2 and BHVO-2 were both consistent with the values measured by previous studies.…”

“…(2022) 19 . The second one is K, which has a distribution coefficient similar to that of Mg in cation resin and it is difficult to absolutely separate from Mg especially for high-K2O samples.…”