A portable and field optical emission spectrometry coupled with microplasma trap for high sensitivity analysis of arsenic and antimony simultaneously

In this work, a portable and reliable optical emission spectrometric (OES) instrument based on solid acid hydride generation (HG) and subsequent in situ dielectric barrier discharge (DBD) preconcentration was first developed for simultaneous and field analysis of ultratrace As and Sb in environmental water. In situ DBD fulfilled both gas phase enrichment (GPE) and excitation; effective enrichment made it possible to use a low-cost charge coupled device (CCD) as detector. To simplify field protocol, solid tablet made from sulfamic acid was first used to replace hydrochloric acid for co-generation of As and Sb hydrides. Moisture interference was eliminated by carrier gas sweeping without any desiccant. After calculating peak volume for emission data handling, detection limits (LODs) were 0.5 mu g L-1 for As and 0.2 mu g L-1 for Sb, respectively, with < 3% relative standard deviations (RSDs) at 10 mu g L-1; linear dynamic ranges (R-2 > 0.995) were 2-200 mu g L-1 for As and 1-200 mu g L-1 for Sb, respectively. The results agreed with certified values of CRMs and recoveries were 87-97% vs. inductively coupled plasma mass spectrometry. The running costs can be controlled within one dollar per use. This HG-in situ DBD trap-OES scheme, with demonstrated advantages in sensitivity, low-cost, power ( < 60 W), size (0.6 m x 0.5 m x 0.3 m), weight (15 kg), gas consumption (300 measurements per 4 L tank), and multi-element capability, was implemented in a miniature spectrometer for field analysis.