Micro-distillation system for formaldehyde concentration detection

Abstract

A micro-distillation system is presented for formaldehyde concentration detection in food products. The proposed system consists of a micro-distillation device, a micro-condensed device, micro-distillation chip, a high-pressure steam tank, a temperature controller, and a cooling system. The distillation chip is fabricated on polymethylmethacrylate (PMMA) substrates using a CO2 laser system and comprises three distilling chambers, a condenser micro-channel and a cooling micro-channel. In the proposed system, the formaldehyde sample is injected into the distillation chip and a high-pressure steam supply is used to vaporize the formaldehyde and carry it to the condenser region of the chip. The formaldehyde vapor is condensed under the effects of the low-temperature cooling channel and is transported to the collection region of the device. Finally, a colorimetric detection process is performed to measure the formaldehyde concentration of the collected sample using a commercial spectrophotometer. The validity of the proposed system is investigated using a control sample with a formaldehyde concentration of 6ppm. It is shown that a distillation efficiency as high as 98% can be obtained given a steam pressure of 4bar. The real-world applicability of the proposed micro-distillation system is demonstrated by measuring the formaldehyde concentrations of 18 commercial Chinese herb samples.