DIAGNOSTIC INVESTIGATIONS OF AEROSOLS WITH VARYING WATER-CONTENT IN INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

Measurements of axial and radial ion intensity distributions and also of ion energy characteristics by a simple bias potential technique, gi ving a representation of the kinetic energy distributions, have been a pplied to study the influence of water vapour on the behaviour of aero sols in inductively coupled plasma mass spectrometry. The full range o f moisture content has been covered: from dry aerosols generated by so lid evaporation to wet aerosols formed by the addition of an increasin g amount of water vapour as well as vice versa from pneumatically gene rated wet aerosols to dry aerosols by applying dehumidification techni ques. As an alternative to humidification of a dry aerosol, hydrogen a ddition was considered. Comparison of results was performed on the bas is of identical values for power and nebulizer flow rate, while sampli ng distance and bias potential were always individually optimized. A s trong dependence on the content of water or hydrogen was observed offe ring a promising opportunity to influence the analytical performance w hile providing the basis for a consistent interpretation of the result s. Exploitation of the method in analysis requires that sampling dista nce and bias potential be taken into account in optimization procedure s in addition to nebulizer flow rate and power, to which optimization procedures have been restricted in most applications so far.