Determination of trace elements in natural waters by inductively coupled plasma time of flight mass spectrometry after flow injection preconcentration in a knotted reactor.

A flow injection on-line sorption system was developed for the separation and preconcentration of traces of Ag, Cd, Co, Ni, Pb, U and Y from natural water samples with subsequent detection by ICP TOF MS. Simultaneous preconcentration of the analytes was achieved by complexation with the chelating reagent 1-phenyl-3-methyl-4-benzoylpyrazol-5-one immobilized on the inner walls of a (200cm x 0.5mm) PTFE knotted reactor. The analytes were eluted and transported to an axial ICP TOF MS system with 1% (v/v) HNO(3) containing 0.3microg l(-1) of Rh as an internal standard using ultrasonic nebulization. The detection limits (3sigma) varied from 0.3ng l(-1) for Y to 15.2ngl(-1) for Ni and the precision (R.S.D.) was better than 4%. Using a loading time of 90s and a sample flow rate of 4.5ml min(-1), enhancement factors of 3-14 were obtained for the different analytes in comparison with their direct determination by ICP TOF MS with ultrasonic nebulization without preconcentration. The accuracy of the method was demonstrated by analysis of water based certified reference materials.

Electrothermal atomization of arsenic, antimony and thallium using a graphite atomizer with refractory metal platforms.

The electrothermal atomization of the volatile elements arsenic, antimony and thallium from a refractory metal platform consisting of a tungsten coil and/or a refractory metal foil with the dimensions of a conventional graphite platform was studied. Several combinations of refractory metal platforms were investigated, as follows: W platform; Ta platform; W coil; W coil on a W platform and W coil on a Ta platform. The best combination for these elements as regards both thermal stabilization and sensitivity is the W coil on a Ta platform. Thermal stabilization is also achieved with a W coil on a W platform. The presence of Pd-containing chemical modifier favors the thermal stabilization of the analytes. The sufficient amount is 2 micrograms of Pd. The maximal temperatures of pyrolysis are higher (arsenic, antimony) or equal (thallium) to those when using different chemical modifiers, added as solutions. It may be concluded, that the refractory metal platforms act as "built-in modifiers". They are suitable for the determination of arsenic, antimony and thallium in samples of complex matrix composition where high thermal stability of the analytes during the pyrolysis step is required.

Slurry sampling ETAAS determination of sodium impurities in optical crystals of potassium titanyl phosphate and potassium gadolinium tungstate.

Slurry sampling ETAAS was successfully applied to the determination of sodium impurities in single crystals of potassium titanyl phosphate (KTP) and potassium gadolinium tungstate (KGW). Platform atomizers coated with titanium carbide or tungsten carbide, respectively, were used in order to avoid sensitivity drift due to the changes in the composition and the structure of the platform surface. Calibration curves with aqueous standards could be used for the KGW slurry (no matrix effects); analysis of KTP slurry required the standard additions method. The precision of the proposed method was better than 3% R.S.D. The results obtained by the present method showed a good agreement with those obtained by an independent method-flame AAS after sample digestion, which is an evidence for the good accuracy of the proposed method.