Ion microprobe determination of water in silicate glasses: methods and applications

Ion probe measurements offer the advantage of in situ determination of water content with a few micrometres spatial resolution. After a brief review of ion microprobe procedures used for the determination of water concentration in silicates, we examine three important effects on analytical precision: (1) the effect of energy filtering on the background; (2) the variation of the H/Si ratio with time; and (3) the dependence of the H/Si ratio on the composition of the matrix, which requires the use of standards close in chemical composition to the unknowns. y, applications of this method to the determination of water in glasses quenched from water-saturated melts, to experimental products consisting of a mixture of glass and crystals, and to natural melt inclusions illustrate the advantages and the limitations of the ion microprobe.