Variable microfluidic dosing valve for gas chromatography

Abstract

Miniaturization coupled with the introduction of microfluidic systems and devices into the chromatograph hardware is one of the main approaches to the creation of modern gas chromatographic equipment. For variable sample dosing in automatic mode, a microfluidic dosing valve based on microelectromechanical systems was developed. The manufactured device provides multi-point calibration with a single calibration gas mixture. Two methods for constructing a calibration dependence were implemented using the developed dosing device: a calibrated loop for 250 μl taken as a constant dosing loop and calibration solutions (gas mixtures of propane in helium (GSO 10463–2014) with concentrations of 0.0025, 0.025, 0.25, 0.5б and 1.25 % vol.) were used in the first method, whereas in the second one a variable dosing provided by the developed microfluidic dosing valve which consisted in the possibility of introducing a different amount of the calibration gas mixture of propane in helium (2.5 % vol.) into the chromatographic column due to changing the time of sample injection at a constant pressure was implemented. The experiment was carried out on a PIA gas microchromatograph with a MEMS column (a sectional plane of 1 × 1 mm and a 1-m channel) with a Carbopak B adsorbent. It is shown that the use of the developed dosing device as part of the PIA gas microchromatograph makes it possible to carry out a metrologically assured quantitative analysis.