DETERMINATION OF BORON USING MANNITOL-ASSISTED ELECTROTHERMAL VAPORIZATION FOR SAMPLE INTRODUCTION IN INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

The possibility of improving the detection sensitivity for boron with the use of mannitol as a chemical modifier in electrothermal vaporizat ion inductively coupled plasma mass spectrometry (ETV-ICP-MS) is prese nted. Experiments were performed by adding mannitol to a boron analyte solution to form a boron-mannitol complex and then injecting the resu lting product into the ETV-ICP-MS system for determination, The effect of mannitol on the signal pulse of boron was investigated by monitori ng the analyte through a heating cycle from 150 to 2600 degrees C, The appearance of several marked signal pulses at temperatures between 42 5 and 1500 degrees C was observed and assumed to result from the vapor ization of boron-mannitol complexes. The signal intensity of boron in the presence of mannitol was found to be considerably enhanced in comp arison with that in its absence, The optimization of the ETV and ICP p arameters and the amount of mannitol added and the comparison of manni tol with different modifier systems mere subsequently investigated. It was found that by following the established method the sensitivity fo r boron in the presence of mannitol can be improved by a factor of 84 compared with that without the modifier, and the limits of detection ( 3 s) achieved in the presence of mannitol can be as low as 0.2 ng ml(- 1) with a 20 mu l injection. The large boron sensitivity enhancement i n the presence of mannitol in ETV-ICP-MS is attributed to the formatio n of a boron-mannitol complex that is subsequently vaporized from the graphite surface and transported with the assistance of mannitol to th e plasma. A novel application with mannitol, which acts both as a prec oncentrating agent for boron in the chemical separation process and as a modifier in the ETV-ICP-MS for the determination of boron in trichl orosilane, is also presented.