Performance enhanced "tunable" capillary microwave-induced plasma mass spectrometer for gas chromatography detection

Improvements in the stability and performance of a capillary microwave-indu ced plasma-mass spectrometer (MIP-MS) were achieved by optimizing power tra nsfer to the cavity using a tunable coaxial MIP. The MIP, operating at atmo spheric pressure, was sustained with 30 mL/min He and 60 W of power, Measur ement precision and sensitivity for the standard waveguide and coaxial syst ems were determined using 16 organochlorine pesticide solutions separated b y gas chromatography (GC), The linear dynamic range obtained with the tunab le MIP-MS extended over 3 orders of magnitude, a 10 time improvement with r espect to the standard MIP. Detection limits were between 3 and 19 pg of Cl mol(-1) s(-1) 7 times lower than the detection limits obtained with the no ntunable MIP-MS, Analysis of pesticides containing sulfur atoms was also po ssible, further demonstrating multielement MIP-MS detection. Excellent accu racy (10% recovery) and precision (5% RSD) were found for the detection of the pesticides in a petroleum-contaminated reference soil. By placing the G C column at the plasma expansion stage, molecular fragmentation of a mixtur e of volatile organic compounds was also demonstrated. With the MS operated in the selected ion monitoring mode, measurement sensitivity was similar t o 500 pg/s per compound.