Microfluidic detection platform with integrated micro-spectrometer system

A microfluidic detection platform is presented for the rapid and low-cost measurement of preservatives in foods. The microfluidic platform consists mainly of an integrated microfluidic reaction chip and a micro-spectrometer detection system. The reaction chip further involves a heater and a micromixer zone for sample/reagent mixing and reaction, and is fabricated on a PMMA substrate using a CO2 laser. The feasibility of the presented platform is confirmed by measuring the concentration of sorbic acid in food samples. In the analysis process, the extracted sample is mixed with Iron(III) reagent and Thiobarbituric acid (TBA) by a gas driving force and a colorimetry reaction (oxidation reaction) of the mixture (pink complex) is then caused by a micro-heater system. The pink complex is driven to the detection chamber of the microfluidic reaction chip, where it is analyzed by the micro-spectrometer system under illumination of a 530 nm (wavelength) LED light source. Finally, the sorbic acid concentration is derived from the measured value using a calibration curve constructed on the basis of seven sorbic acid control samples with known concentrations ranging from 0.02-0.5 g/kg. The results indicated that the sorbic acid concentration detections of the 15 commercial samples obtained using the presented platform differed from the detections obtained using a standard macroscale HPLC method by no more than 7.5%. In a further series of tests, the determination coefficients for benzoic acid, sulfur dioxide and formaldehyde are found to be R-2 = 0.9961, 0.9933 and 0.9968, respectively. In other words, the general feasibility of the proposed platform for preservative detection in foods is confirmed.