LaMotte DC1600 Colorimeter - Manual (Page 25)

CHROMIUM (HEXAVALENT)
DIPHENYLCARBOHYDRAZIDE METHOD CODE 3645
QUANTITY CONTENTS CODE
10 g *Chromium Reagent Powder *V-6276-D
1 Spoon, 0.1 g, plastic 0699
1 Filter Paper 0465-H
1 Funnel, 20 mL 2-2135
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are supplied for
these reagents. For your safety, read label and accompanying MSDS before using.
Chromium may be present in water containing waste from industries such as metal plating, or in overflow water from large
air conditioning units where chromate compounds are frequently added to cooling water to control corrosion. It is
considered to be a toxic chemical and, if present in an amount of over 0.5 ppm, is evidence of contamination from
untreated or incompletely treated industrial waste.
Chromium is one of a class of heavy metals found in the bottom muds of polluted bodies of waters. Certain shellfish are
capable of concentrating this element, endangering the health of its ultimate consumer, human or animal.
APPLICATION: Drinking, surface, & saline waters; domestic and industrial wastewaters.
RANGE: 0 – 1.0 ppm Chromium
METHOD: Hexavalent chromium reacts with 1,5 diphenylcarbohydrazide under acidic conditions to form
a red-purple color in proportion to the amount of chromium present.
SAMPLE HANDLING
& PRESERVATION: Analysis for chromium should be made as quickly as possible after sample collection since
storage in glass or plastic containers may result in low chromate values.
INTERFERENCES: High concentrations of mercurous and mercuric ions may impart a blue color to the chromium
determination. Iron and vanadium in concentrations above 1 mg/L may result in a yellow
color. However, the vanadium color becomes negligible 10 minutes after the addition of
diphenylcarbohydrazide.
25