A demountable nanoflow nebulizer for sheathless interfacing nano-high performance liquid chromatography with inductively coupled plasma mass spectrometry

Abstract

For direct analyses of micro-samples and the hyphenation with nanoflow separation techniques, a low-cost demountable nanoflow nebulizer was fabricated for inductively coupled plasma mass spectrometry (ICP-MS). A small-bore capillary (20 μm) with a tapered tip served as the sample capillary of the nebulizer. The gas orifice diameter, the internal diameter and the wall thickness at the tip of the sample capillary were 160, 20, and 5 μm, respectively, which ensured stable generation of aerosol by the nebulizer at nanoflow rates down to 50 nL min⁻¹ and an ultra-low aspiration rate (80 nL min⁻¹). Narrower aerosol size distribution and higher analyte transport efficiency (nearly 100%) were obtained with the proposed nebulizer than with the previous demountable capillary microflow nebulizer. The sensitivity and detection limit of the proposed nebulizer at 500 nL min⁻¹ were about one third of those obtained by using the demountable capillary microflow nebulizer at 5 μL min⁻¹, whereas the precision of the former at 500 nL min⁻¹ was even to some extent superior over that obtained with the latter at 5 μL min⁻¹. Furthermore, the ICP-MS instrument could tolerate direct introduction of 100% organic solvents by using the developed nebulizer operating at nanoflow rates. It was utilized to sheathless interface nano-high performance liquid chromatography with ICP-MS for arsenic speciation analysis with good accuracy and precision, proving its strong robustness and good suitability.