Multifunctional microchip-based distillation apparatus I - Steam distillation for formaldehyde detection.

A multifunctional microchip-based distillation apparatus for distilling and detecting formaldehyde (CH2O) in food products is developed. The presented apparatus comprises a disposable microchip, a steam supply system, and a recirculating cooling water supply. The microchip is formed on PMMA substrates by laser ablation and includes a sample zone, a flash distillation zone, a cooling zone, a condensation zone, and a collection zone. In the presented method, the CH2O sample is placed in the microchip and is vaporized by the high-throughput vapor supply and driven through the condensed zone. The condensed CH2O liquid is guided into the collection zone of the microchip. Finally, the distilled CH2O solution is determined using an AHMT spectrometry method and a paper-based RGB (red, green and blue) intensity analysis method. A distilled efficiency is as high as 98%, when a vapor stream rate is 0.4 ml/min and a distilled time is 10 min. Moreover, both detection methods show linear relationships of the corresponding CH2O concentrations. The actual sample suitability of the presented multifunctional microchip-based distillation apparatus is confirmed by analyzing the CH2O concentrations of 21 commodities.