Field Screening of Total Residual Chlorine | US EPA
May 9, 2024 · Field branches quality systems and technical procedures. This document describes methods and considerations to be used and observed when conducting field screening of total residual chlorine in surface water and wastewater effluent.
The SwifTest Dispenser for Total Chlorine can be used in place of the powder pillow in the test procedure. One dispensation is equal to one powder pillow for 10-mL samples.
titrating with Ferrous Ammonium Sulfate as in the titrimetric method, the sample is placed in a test tube or photometer cell and the chlorine content is measured with a spectrophotometer or photometer.
As you are aware, EPA lists test methods for permit monitoring in 40 CFR § 136. On a national level the lowest published detection limit provided for the methods specified in §136 is 0.01 mg/l. This detection limit is for Standard Methods 4500 Cl E and G. This level is based on testing under “ideal” conditions.
If the test result is over-range, or if the sample temporarily turns yellow after the reagent addition, dilute the sample with a known volume of high quality, chlorine demand-free water and do the test again.
When using the DPD colorimetric method for total residual chlorine, gel standards will be used for meter verification. The gel standards must be verified by the
Open a DPD total chlorine powder packet and add the contents to the sample cell. g. Replace the cap on the sample cell and swirl or mix for approximately 20 seconds.
In the total residual chlorine (TRC) method, chlorine liberates iodine from potassium iodide when an excess amount of iodine is present. The liberated iodine reacts with DPD
The most common equipment used to monitor for TRC in the field includes portable colorimeters and bench top spectrophotometers, similar to those pictured below, utilizing Standard Methods 4500Cl-G.
DPD colorimetric method are in poor agreement with both the ISE and amperometric titration method, with measurement errors of up to 1.2 ppm. In large part, this error is likely explained by changes in the turbidity of the water and the presence of color-absorbing natural organic matter, which can have a significant effect on colorimetric