Multimode Sample Introduction System Research Articles

Comparison between hydride generation and nebulization for sample introduction in the determination of lead in plants and water samples by inductively coupled plasma mass spectrometry, using external calibration and isotope dilution

Four inductively coupled plasma mass spectrometric methods: nebulization sample introduction with external calibration; hydride generation with external calibration; isotope dilution with nebulization; and isotope dilution with hydride generation, have been tested and compared. Multimode Sample Introduction System (MSIS™) was employed in either nebulization or hydride generation mode. Best limits of detection (below 0.1 μg L − 1 ) and accuracy were obtained for isotope dilution techniques in hydride generation and sample nebulization mode. A mixture of HNO 3 and H 2O 2 served both for microwave-assisted digestion as well as a medium for subsequent plumbane generation. Optimal reagent concentrations for hydride generation stage were 0.1 mol L − 1 HNO 3, 0.28 mol L − 1 H 2O 2 and 1.5% m/v NaBH 4. Critical effects of acidity, blanks and concomitants have been discussed. Analytical methods were validated by use of plant and water certified reference materials and spiked high-salt solutions (seawater and 20% m/v NaCl) at lead levels in nanograms per gram to micrograms per gram range.

Simultaneous determination of hydride (Se) and non-hydride-forming (Ca, Mg, K, P, S and Zn) elements in various beverages (beer, coffee, and milk), with minimum sample preparation, by ICP–AES and use of a dual-mode sample-introduction system

A method has been developed enabling direct analysis (i.e. after dilution only) of beer, instant coffee, milk, and milk powder by ICP-AES. Analysis of the beverages after dilution with a low concentration of HNO3 was used for accurate determination of essential minor and trace elements (Ca, Mg, K, P, S, and Zn). Selenium, introduced as the hydride, was determined simultaneously with the other non-hydride-forming elements using the commercial multi-mode sample-introduction system (MSIS). To obtain accurate results, however, some simple pre-treatment was needed. Analysis was also performed after microwave-assisted decomposition of the samples. Three different modes of sample-preparation, i.e. dilution only, partial decomposition (aqua regia treatment), and complete decomposition were compared. The results obtained by use of the three different sample-preparation methods were in very good agreement. Results from analysis of certified reference material (SRM 1459 non-fat milk powder) also verified the accuracy of the methods. The limit of detection obtained for Se using dual-mode sample introduction was 0.5 ng mL(-1), which corresponds to approximately 2 ng g(-1) in beer and approximately 4 ng g(-1) in coffee and milk when using the recommended procedure.

The use of a modified Multimode Sample Introduction System for the simple and rapid determination of cadmium by chemical vapour generation atomic absorption spectrometry

A cold vapour (CV) generation system incorporating a modified version of a Multimode Sample Introduction System (MSIS™) was investigated for the determination of cadmium by atomic absorption spectrometry (AAS). The system allowed for the use of the relatively high concentrations of reagents required for efficient production of volatile cadmium without the significant bubbling, frothing, and associated liquid transport problems common to conventional gas–liquid separators while maintaining a low volume. The low volume produced narrow peaks (approximately 5 s base peak width). A detection limit of 0.026 μg L −1 (3s) was found with a precision of 2.5% for a 0.5 μg L −1 standard ( n=4) and a linear dynamic range up to approximately 10 μg L −1. The addition of thiourea, cobalt, and nickel was found to overcome interferences and produce good agreement between experimental and certified values for Natural Water and Mussel Tissue standard reference materials (SRM).