A test strip for chloride analysis in environmental water

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Accurate chloride determination is crucial for water quality assessment.
• Existing methods can be complex or require specialized equipment.
• Development of simple, cost-effective sensors is needed for widespread application.

Purpose of the Study:

• To develop a disposable and reversible test strip for selective chloride detection.
• To evaluate the sensor's performance characteristics, including selectivity and response time.
• To validate the test strip for chloride determination in various water types.

Main Methods:

• A polyester-based test strip with a sensing zone containing poly(vinyl chloride) (PVC) membrane, trioctyltin chloride (ionophore), and 4',5'-dibromofluorescein octadecyl ester (chromoionophore).
• Chloride detection via a co-extraction system with hydrogen ions, indicated by a color change (red to orange).
• Spectrophotometric measurement of absorbance at 534 nm after immersing the strip in a pH 2.0 buffered water sample.

Main Results:

• The sensor exhibits linear response in the activity range of 0.15–24.7 mM.
• Achieved a detection limit of 0.15 mM with good reproducibility (intermembrane 6.4% RSD, intramembrane 4.5% RSD).
• Successfully applied to determine chloride in tap, well, stream, and sea water samples, showing agreement with a reference method.

Conclusions:

• The proposed disposable test strip is an inexpensive, selective, and sensitive method for chloride determination in water.
• The sensor utilizes conventional instrumentation and offers a simple procedure for on-site analysis.
• This technology presents a practical solution for routine water quality monitoring.