Analytical Sciences

Double-sided Microfluidic Device for Speciation Analysis of Iron in Water Samples: Towards Greener Analytical Chemistry

Napaporn YOUNGVISES,*1 Porapichcha THANURAK,*1 Thanatcha CHAIDA,*1,*2 Jaroon JUKMUNEE,*3 and Awadh ALSUHAIMI*4

*1 Innovative Green Chemistry Research Unit, Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathum Thani, 12120, Thailand
*2 Center of Scientific Equipment for Advanced Research, Thammasat University, Pathum Thani, 12120, Thailand
*3 Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand
*4 Department of Chemistry, Faculty of Science, Taibah University, Prince Naif Road, AlMadeinah AlMunwaraha, 42353, Saudi Arabia

Microfluidics minimize the amounts of reagents and generate less waste. While microdevices are commonly single-sided, producing a substrate with microchannels on multiple surfaces would increase their usefulness. Herein, a polymethymethacrylate substrate incorporating microchannel structures on two sides was sandwiched between two polydimethylsiloxane sheets to create a multi-analysis device, which was used for the spectrophotometric analysis of the ferrous ion (Fe²⁺) and the ferric ion (Fe³⁺), by utilizing colorimetric detection. To monitor the signals from both channel networks, dual optical sensors were integrated into the system. The linear ranges for Fe²⁺ and Fe³⁺ analyses were 0.1 – 20 mg L⁻¹ (R² = 0.9988) and 1.0 – 40 mg L⁻¹ (R² = 0.9974), respectively. The detection limits for Fe²⁺ and Fe³⁺ were 0.1 and 0.5 mg L⁻¹, respectively. The percent recoveries of Fe²⁺ and Fe³⁺ were 93.5 – 104.3 with an RSD < 8%. The microdevice demonstrated capabilities for simultaneous analysis, low waste generation (7.2 mL h⁻¹), and high sample throughput (180 h⁻¹), making it ideal for greener analytical chemistry applications.

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