A microfluidic system for introduction of nanolitre sample in inductively coupled plasma mass spectrometry using electrokinetic flow combined with hydrodynamic flow

Abstract

A microfluidic system for introducing nanolitre sample in inductively coupled plasma mass spectrometry using electrokinetic flow combined with hydrodynamic flow was developed, which consisted of a microfluidic chip, a syringe pump, a high voltage power supply, a homemade microflow nebulizer and a heated single pass spray chamber. In the microfluidic chip, the sample in the reservoir S automatically flew across the intersection P 1 to the reservoir SR under hydrodynamic pressure. Two porous polymer plugs C 1 and C 2 were created on the microchip to isolate electrokinetic flow from the pressure-driven flow. Once a high voltage between S and buffer reservoir B was applied , the sample was driven through the porous polymer plug C 1 into the metering channel by electrokinetic force. Simply changing the sampling time can freely optimize the sampling volume down to 0.18 nL, which was injected into the nebulizer by the pressure-driven makeup solution. The nanolitre sample introducing system has the advantages of low sample consumption, satisfactory precision, low sampling dead volume (0.38 nL) and low sampling dead time (0.42 s). The proposed system was successfully applied to determine platinum content in a serum sample of a cancer patient on cisplatin chemotherapy. The sample consumption of 1.8 nL was about 10 5 times less than that with the conventional sampling system. The sample throughput up to 112 h À1 could be achieved with the detection limit of 64 ng L À1 for 195 Pt. The content of Pt in the sample was 8.4 AE 0.3 mg L À1 , agreeing well with that (8.5 AE 0.3 mg L À1 ) determined by the conventional sampling system.

Coupling nanoliter high‐performance liquid chromatography to inductively coupled plasma mass spectrometry for arsenic speciation

“…An ICP‐MS (X Series Ⅱ , Thermo Fisher Scientific, USA) was operated in the time‐resolved analysis mode for the detection of arsenic at a mass isotope of 75. The interface for coupling nanoHPLC to ICP‐MS consisted of the previous nanoflow nebulizer and a single pass spray chamber heated to 90°C . A model HI 98128 pH‐meter (Hanna Instrument, Italia) assisted adjustment of pH values of mobile phases.…”

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

“…The conventional sample introduction system of ICP-MS was replaced by the fabricated nanoow nebulizer coupled with a heated single pass spray chamber (heated to 90 C). 17,18 Adjustment of pH was performed with the assistance of a HI 98128 pH-meter (Hanna Instrument, Italia). A syringe pump (Model 35-2226, Harvard Apparatus Inc.) equipped with a 10 mL syringe was employed to continuously feed solutions to the nanoow nebulizer.…”

Atomic spectrometry update: review of advances in atomic spectrometry and related techniques

“…Cheng et al 52 have developed a microuidic system for nanolitre sampling based on a microuidic chip using a demountable capillary microow nebulizer with a heated, single-pass spray chamber, a negative pressure sampler, a syringe pump and an HV supply. The system combines both electrokinetic and hydrodynamic ow, isolated from each other by porous polymer plugs fabricated into the microchannels, and operated with a sample consumption of 1.8 nL.…”