Application of 1013 ohm Faraday cup current amplifiers for boron isotopic analyses by solution mode and laser ablation multicollector inductively coupled plasma mass spectrometry. (27th November 2017)

• Record Type: Journal Article
• Authors: Lloyd, Nicholas S.; Sadekov, Aleksey Yu.; Misra, Sambuddha
• Is Part Of: Rapid communications in mass spectrometry. Volume 32:Number 1(2018)
• Page Start: 9
• Page End: 18
• Publication Date: 2017-11-27
• Subjects: Mass spectrometry -- Periodicals; 543.65
• DOI: 10.1002/rcm.8009
• Languages: English
• ISSNs: 0951-4198

Abstract

Abstract : Rationale: Boron isotope ratios (δ 11 B values) are used as a proxy for seawater paleo‐pH, amongst several other applications. The analytical precision can be limited by the detection of low intensity ion beams from limited sample amounts. High‐gain amplifiers offer improvements in signal/noise ratio and can be used to increase measurement precision and reduce sample amounts. Methods: 10 13 ohm amplifier technology has previously been applied to several radiogenic systems, but has thus far not been applied to non‐traditional stable isotopes. Here we apply 10 13 ohm amplifier technology for the measurement of boron isotope ratios using solution mode MC‐ICP‐MS and laser ablation mode (LA‐)MC‐ICP‐MS techniques. Precision is shown for reference materials as well as for low‐volume foraminifera samples. Results: The baseline uncertainty for a 0.1 pA 10 B + ion beam is reduced to <0.1 ‰ for a typical measurement period. The external precision is better than 0.2 ‰ (2SD) for δ 11 B measurements for solution samples containing as little as 0.8 ng total boron. For in situ microanalyses with LA‐MC‐ICP‐MS, the external precision of 11 B/ 10 B from an in‐house calcite standard was 1 ‰ (2SD) for individual spot analyses, and 0.3 ‰ for the mean of ≥10 replicate spot analyses. Conclusions: 10 13 ohm amplifier technology is demonstrated to offer advantages for the determination of δ 11 B values by both MC‐ICP‐MS and LA‐MC‐ICP‐MS for small samples of biogenic carbonates, such as foraminifera shells. 10 13 ohm amplifier technology will also be of benefit to other non‐traditional stable isotope measurements.