Chloride / Salt


Test Method Technical Information


Tests For: Chloride Salt in water
Tests Range: 0–50 mg/L Cl to 0–50000 mg/L NaCl
Reagent Chemistry Used: Silver nitrate
Basis of Test Method: Standard Method 4500-Chloride-B
Method Detection Limit*: 0.10 mg/L
Limit of Quantification**: 0.33 mg/L

*The Method Detection Limit (MDL) is defined as the minimum measured concentration of a substance that can be reported with 99% confidence to be different from the method blank results.
**The Limit of Quantification (LOQ) is the smallest quantity that can be detected with reasonable certainty for a given analytical procedure.

Testing for Chloride

The Palintest Chloridol test provides a simple method for measuring chloride salt levels. There are many applications in water technology that require determination of chlorides. These include the measurement of low levels of chloride to determine the extent of carry-over in boiler condensates; chloride determination to assess salt build-up in swimming pools or boiler waters; and measurement of high chloride levels for testing sea water or determining the saltiness of brackish waters. A further application is for checking swimming pools where salt has been artificially added to simulate sea water bathing, or where this is necessary for the operation of certain types of electrolytic hypochlorite generator.

The test can be used for measuring these widely different chloride concentrations by varying the sample size selected. The test ranges covered are 0–50 mg/L Cl, 0–500 mg/L Cl, 0–10,000 mg/L NaCI and 0–50,000 mg/L NaCI.

Reagent Chemistry

The Palintest Chloridol test is based on a tablet reagent system containing silver nitrate. Chlorides react with the silver nitrate to produce insoluble silver chloride. At the chloride levels encountered in the test, the insoluble silver chloride is observed as turbidity in the test sample. The degree of turbidity is proportional to the chloride concentration and is measured using a Palintest Photometer.


The test is carried out under acidic and oxidising conditions to prevent interference from complexing agents such as EDTA and polyphosphates, and from any reducing substances which may be present in the water. Polyacrylates do however interfere, and the test should not be used on industrial waters using polyacrylate-based treatments.

The formation of the precipitate in the Chloridol test may be subject to matrix effects in the presence of high total dissolved solids (TDS). The 0–50 mg/L Cl range is calibrated only for use on softened waters and condensates. It should not be used for other samples. The dilution step in the other ranges reduces the TDS to acceptable levels and prevents this effect.

EPA, Definition and Procedure for the Determination of the Method Detection Limit, Revision 2, Dec 2016.
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”).