Pneumatic nebulization-photochemical vapor generation dual mode sample introduction system
View Patent ↗Efficient and economic devices and methods for dual-mode sample introduction of liquid samples to an analytical detector exemplified by an inductively coupled plasma mass spectrometer (PVG-ICPMS) or an inductively coupled plasma optical emission spectrometer (ICPOES) are described. Various embodiments of pneumatic nebulization (PN)-photochemical vapor generation (PVG) dual-mode introduction can enhance introduction efficiency for PVG-active elements and smooth, bubble-free nebulization for all elements. A compact yet highly efficient porous membrane gas-liquid separator (MGLS) in its various embodiments plays a key role in systems and methods described.
1 . A method of sample introduction to an ICP-based spectrometer comprising the steps of:
a) passing a liquid sample analyte exposure to a UV source to produce a photochemically reduced sample analyte stream,
b) passing said photochemically reduced sample stream over a porous membrane to separate bubbles in the liquid to produce a debubbled liquid stream,
c) nebulization of the debubbled liquid stream, and,
d) feeding the mist-vapor mixture to an ICP-based spectrometer.
2 . The method of claim 1 wherein the porous membrane separating gas to one side of the membrane and liquid on the other side of the membrane is made of polytetrafluoroethylene (PTFE), PCTFE (polychlorotrifluoroethylene), FEP (fluorinated ethylene propylene), or perfluoroalkoxy (PFA).
3 . The method of claim 1 of passing said photochemically reduced liquid sample stream over said porous membrane with the liquid sample on one side of the membrane and gas phase on the other side of the membrane.
4 . The method of claim 3 wherein the gas phase is swept by a purge gas stream.
5 . The method of claim 4 wherein the purge gas stream is an inert gas stream.
6 . The method of claim 1 wherein the sample introduction is to an inductively coupled plasma mass spectrometer.
7 . The method of claim 1 wherein the sample introduction is to an inductively coupled optical emission spectrometer.
8 . An inductively coupled plasma mass spectrometer with a membrane gas flow separator system for dual-mode pneumatic nebulization-photochemical vapor generation sample introduction comprising:
a photochemical reactor with a source of UV light for photochemical reduction of an analyte stream for analysis;
a porous membrane gas-liquid separator (MGLS) or debubbler to practically eliminate segmentation of photoreactor effluent;
a nebulizing system connected to the output stream of the porous membrane gas-liquid separator to nebulize the liquid separated from bubbles; and,
a spectrometer connected to the analyte mist stream.
9 . The porous membrane gas-liquid separator (MGLS) system of claim 8 with the two cavities,
wherein the cavities are on either side of the porous membrane,
one cavity is for a liquid and one cavity for a gas stream, wherein a photoreactor effluent flows through the liquid cavity in contact with the porous membrane, with removal of bubbles that permeate through the membrane into the gas cavity which is connected to a gas inlet admitting a purge gas to sweep bubbles to the gas outlet.