LaMotte SMART Spectro Spectrophotometer - Manual (Page 100)

CHROMIUM-HEXAVALENT,
TRIVALENT & TOTAL
DIPHENYLCARBOHYDRAZIDE METHOD • CODE 3698-SC
QUANTITY CONTENTS CODE
60 mL * Sulfuric Acid, 5N *7681-H
10 g * Chromium Reagent Powder *V-6276-D
15 mL * Sodium Azide, 5% *7683-E
30 mL Potassium Permanganate, 0.5% 7682-G
60 mL Deionized Water 5115PT-H
1 Pipet, plain, glass, w/cap 0341
1 Pipet, 1.0 mL, plastic 0354
1 Spoon, 0.1 g, plastic 0699
1 Graduated Cylinder, 50 mL, glass 0418
1 Erlenmeyer Flask, 125 mL, glass 0431
1 Test tube holder 1113
1 Filter Paper 0465
1 Funnel, Plastic 0459
*WARNING: Reagents marked with a * are considered to be potential health hazards. To view
or print a Material Safety Data Sheet (MSDS) for these reagents see MSDS CD or
www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail, phone or fax.
A toxic chemical, chromium is found in two forms in the water; trivalent
chromium (Cr
3+ ) and hexavalent chromium (Cr 6+ ). Chromium enters the
water from industrial waste. Hexavalent chromium is more toxic than trivalent
chromium. Levels greater than 0.5 ppm indicate improperly treated industrial
waste. It is important to maintain chromium levels at or below 0.5 ppm,
because clams and other shellfish will store chromium in their systems,
accumulating levels which may be dangerous to the consumer, whether human
or animal.
APPLICATION: Drinking, surface, and saline waters; domestic and industrial
wastes.
RANGE: 0.00–1.00 ppm Chromium
METHOD: The trivalent chromium is converted to hexavalent
chromium by permanganate under acidic conditions.
Hexavalent chromium reacts with 1,5
diphenyl-carbohydrazide 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.
SMART SPECTRO TEST PROCEDURES 10.04 Chromium-Hexavalent, Trivalent & Total 1/4