Abstract

Analytical data illustrating the typical response characteristics of a commercial inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (Optimass8000 ICP-oa-TOFMS, GBC Scientific Equipment Pty Ltd., Australia) are presented. With optimum instrument response tuned at mid-mass (¹⁰³Rh), limits of detection for a suite of elements representative of m/z 9–238 were estimated to be typically 1 ppt; background counts across the mass range averaged 0.5 Hz; sensitivity was 7 MHz per µg ml⁻¹ (Rh); resolution (FWHM) ranged from 500 (⁷Li) to 2200 (²³⁸U); long-term drift over 700 min was 0.7% h⁻¹; abundance sensitivity was 2.8 × 10⁻⁶ (low mass side) and 7.4 × 10⁻⁵ (high mass side); mass bias ranged from 10% per u at ²⁴Mg to <1% per u at m/z > 80 and isotope ratio precision was demonstrated to be limited by counting statistics when the detector was operated in the pulse counting mode. Matrix effects, while relatively insignificant at 30 ppm NaCl and reaching 60–80% suppression of response at 3500 ppm, had no influence on the measured resolution, mass calibration or isotope ratio accuracy. The instrument faithfully recorded transient signals arising from flow injection sample introduction, from which isotope ratio information free of time skew could be generated.