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

Area of Science:

• Analytical Chemistry
• Microfluidics
• Spectrophotometry

Background:

• Traditional methods for phosphate determination can be time-consuming and require significant reagent volumes.
• There is a need for portable, cost-effective, and low-consumptive analytical systems for field applications.

Purpose of the Study:

• To design and fabricate a microfluidic hydrodynamic sequential injection (μHSI) spectrophotometric system.
• To demonstrate the system's capability for phosphate determination using the molybdenum blue method.
• To evaluate the system's performance in terms of linearity, detection limit, and accuracy in soil samples.

Main Methods:

• Fabrication of a microfluidic channel platform using laser engraving on acrylic.
• Integration of solenoid valves for programmable liquid flow control based on HSI principles.
• Sequential aspiration of reagents (ascorbic acid, sample/standard, molybdate) and carrier water for phosphate detection via molybdenum blue spectrophotometry.

Main Results:

• A linear calibration graph was obtained for phosphate concentrations ranging from 0.1 to 6 mg P L⁻¹.
• The system achieved a detection limit of 0.1 mg L⁻¹.
• Analysis of soil samples yielded percent recoveries between 91.2% and 107.3%, showing good agreement with batch methods.

Conclusions:

• The developed μHSI system is compact, durable, portable, and cost-effective.
• The system demonstrates efficient and accurate phosphate determination with minimal chemical consumption.
• The μHSI system is suitable for on-site analysis of phosphate in environmental samples like soil.