Exploiting an automated microfluidic hydrodynamic sequential injection system for determination of phosphate

• Published in: Talanta (Oxford) 2018-01, Vol.177, p.77-85
• Main Authors: Khongpet, Wanpen, Pencharee, Somkid, Puangpila, Chanida, Kradtap Hartwell, Supaporn, Lapanantnoppakhun, Somchai, Jakmunee, Jaroon
• Format: Article
• Language: English
• Subjects: HSI; Hydrodynamic sequential injection; Microfluidic; Molybdenum blue; Phosphate; Soil
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2017.09.018

A microfluidic hydrodynamic sequential injection (μHSI) spectrophotometric system was designed and fabricated. The system was built by laser engraving a manifold pattern on an acrylic block and sealing with another flat acrylic plate to form a microfluidic channel platform. The platform was incorporated with small solenoid valves to obtain a portable setup for programmable control of the liquid flow into the channel according to the HSI principle. The system was demonstrated for the determination of phosphate using a molybdenum blue method. An ascorbic acid, standard or sample, and acidic molybdate solutions were sequentially aspirated to fill the channel forming a stack zone before flowing to the detector. Under the optimum condition, a linear calibration graph in the range of 0.1–6mg P L−1 was obtained. The detection limit was 0.1mgL−1. The system is compact (5.0mm thick, 80mm wide × 140mm long), durable, portable, cost-effective, and consumes little amount of chemicals (83μL each of molybdate and ascorbic acid, 133μL of the sample solution and 1.7mL of water carrier/run). It was applied for the determination of phosphate content in extracted soil samples. The percent recoveries of the analysis were obtained in the range of 91.2–107.3. The results obtained agreed well with those of the batch spectrophotometric method. [Display omitted] •A microfluidic hydrodynamic sequential injection (μHSI) system was developed.•The μHSI platform was fabricated on an acrylic block by laser engraving.•It was demonstrated for determination of phosphate in soil samples.•The system is automated, compact, low-cost, and consumes small amounts of chemicals.