HIGH-RESOLUTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTRA WITH A QUADRUPOLE MASS FILTER

An inductively coupled plasma mass spectrometer (ICP-MS) system is des cribed in which the quadrupole mass filter can be operated conventiona lly or in the 'second' stability region (with Mathieu parameters q=7.5 47, a=0.0295), With operation in the second region a resolution at hal f-height (R(1/2)) of up to 9000 can be achieved at m/z = 55. At R(1/2) = 5000, a resolution sufficient to separate atomic ions from common m olecular ion interferences (such Fe-56(+) and (ArO+)-Ar-40-O-16), the sensitivity is ca, 10(6) ions s(-1) per mu g mL(-1) of element in solu tion, This sensitivity is comparable to that of current sector ICP-MS systems operated at the same resolution, When the quadrupole is operat ed in the first stability region, the sensitivity is ca. 10(8) ions s( -1) per mu g mL(-1) of element in solution, The continuum background i s high, ca 1000 s(-1), but no attempts have yet been made to reduce th is, The results suggest that with continued development, a high resolu tion quadrupole ICP-MS system will be possible.