Highly sensitive determination method for total carbonate in water samples by flow injection analysis coupled with...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Spectrophotometry

Background:

• Accurate determination of total carbonate in various water types is crucial for environmental monitoring.
• Existing methods may lack sensitivity or on-site capabilities for real-time analysis.

Purpose of the Study:

• To develop a novel, sensitive, and portable spectrophotometric method for on-site total carbonate determination in water samples.
• To investigate the performance of a new flow injection analysis (FIA) system equipped with a gas-diffusion unit.

Main Methods:

• Development of a new color-change system using 4-(2',4'-dinitrophenylazo)-1-naphthol-5-sulfonic acid (DNN5S).
• Utilized a portable FIA system with a custom-designed gas-diffusion unit featuring micro porous PTFE tubing.
• Optimized system parameters including sample size, air bath temperature, gas-diffusion unit length, and flow rates.

Main Results:

• Achieved a rectilinear calibration graph from 1 x 10(-6) M to 10(-3) M with a detection limit of 1 x 10(-6) M carbonate.
• Demonstrated high precision with a relative standard deviation (RSD) of 1.9% for Na2CO3 solutions.
• Successfully determined total carbonate in diverse water samples including river, sea, rain, distilled, and ultra-purified water.

Conclusions:

• The developed spectrophotometric method provides a sensitive, rapid, and on-site approach for total carbonate analysis in water.
• The novel FIA system with the gas-diffusion unit is effective for environmental water quality assessment.
• The method's low detection limit and high precision make it suitable for various water matrices.