Test Method Technical Information


Tests For: Sulfide in Natural and Waste waters
Tests Range: 0–0.5 mg/L
Reagent Chemistry Used: DPD and potassium dichromate11
Method Detection Limit*: 0.02 mg/L
Limit of Quantification**: 0.06 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 Sulfide

Natural waters containing dissolved hydrogen sulfide and other sulfides are found in certain parts of the world, particularly in areas having hot springs. Sulfides are constituents of many industrial wastes such as those from tanneries, gas plants and chemical works. Sulfides can be toxic to fish and aquatic life; and their presence in water supplies gives rise to undesirable tastes and odours.

The Palintest Sulfide Test provides a simple method of measuring total available sulfide over the range 0–0.5 mg/L and is particularly applicable to natural and drinking waters. Higher levels, such as those found in effluents and waste waters, can be determined by diluting the sample.

Reagent Chemistry

This simplified method for the determination of sulfide is based on a reagent containing diethyl-p-phenylene diamine (DPD) and potassium dichromate. Sulfide reacts with this reagent in acidic solution to produce a blue coloured complex. In the absence of sulfide, the reagent produces a pink colour. Chlorine, and other oxidizing agents which normally react with DPD, do not interfere with the test. The reagents are provided in the form of two tablets and the test is simply carried out by adding one of each tablet to a sample of the water.

The colour produced is indicative of the sulfide concentration and is measured using a Palintest Photometer.

Best Practice Advice for Testing

  • To prevent loss of sulfide, collect the sample carefully with a minimum of agitation or aeration. Test the sample as soon as possible after collection.

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”).