Pipette about 10 ml of water sample. Adjust pH 1 using low normality Sulfuric acid.

Place in 100 ml volumetric flask and dilute to mark using distilled water.

Add a sample amount of Diphenyl Carbazide solution.

Shake to mix and let stand for atleast 5 minutes to allow full color development ( color should be violet ).

Read absorbance of sample in a Spectrophotometer at 540 nm wavelength. Use distilled water as blank.

Read atleast 3 the standard solutions with concentrations of (0.05 to 1 ppm) in a Spectrophotometer at 540 nm wavelength using 1 cm cuvette.

Prepare calibration curve from absorbance readings of standard solutions against their corresponding concentrations.

Calculate the Hexavalent Chromium content using Linear regression.

Standard Solutions :

Prepare Chromium Standard Solutions by dissolving Potassium Dichromate in distilled water. Make several dilution to be able to prepare desired concentrations.

Related Posts :
Nitrates (NO3) in Water
IEC 62321 – Hexavalent Chromium Testing Method & Procedure
US EPA 3060A – Hexavalent Chromium Testing Method & Procedure
EN 71 Part 3 ( Testing Procedure )
ASTM F963 -96a / ASTM F963 -07 (Testing Procedure)