Chromium (hexavalent) – LaMotte DC1600 Colorimeter User Manual

Page 25

CHROMIUM (HEXAVALENT)

DIPHENYLCARBOHYDRAZIDE METHOD

CODE 3645

QUANTITY

CONTENTS

CODE

10 g

*Chromium Reagent Powder

*V-6276-D

Spoon, 0.1 g, plastic

0699

Filter Paper

0465-H

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.