Millifluidic chip with a modular design used as a sample pretreatment cartridge for flour and flour food products

The integration of sample pretreatment remains one of the hurdles towards a rapid, automated micro total analytical system (µ-TAS) for real samples. In this paper, a modular design, which was used for sample preparation, has been developed as the polydimethylsiloxane (PDMS) millifluidic chips with channels at a millimeter level. Multiple functional units, including extraction, filtration, mixing and solid phase extraction (SPE), for sample pretreatment were integrated in one chip. In this chip, each functional unit was connected by pump tubings and one-way valves in series to form a fully automated system. Based on the modular design, multiple functional units have been combined in different sequences according to practical needs. In addition, the proposed system has characteristics of miniaturization, portability, and real-time application. Herein, spiked benzoyl peroxide (BPO) in flour samples was used as a model compound to study the system's performances. With a portable integrated Raman spectrometer for detection, the detection limit of BPO was 0.017 g kg⁻¹, with a linear relationship from 0.025 to 0.5 g kg⁻¹. This modular design was demonstrated to be effective and it can be expanded for pretreatment of other food samples.