Sulfate – LaMotte DC1600 Colorimeter User Manual

Page 81

SULFATE

BARIUM CHLORIDE METHOD

CODE 3665

QUANTITY

CONTENTS

CODE

10 g

*Sulfate Reagent

*V-6277-D

Spoon, 0.1 g, plastic

0699

*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.

The most common mineral forms of sulfur are iron sulfide, lead sulfide, zinc sulfide and as calcium sulfate and magnesium

sulfate. In most fresh waters the sulfate ion is the second or third most abundant anion, being exceeded only by bicarbonate

and, in some cases, silicate. Sulfur, in the form of sulfate, is considered an important nutrient element. Mineral springs are

rich in sulfate and feed appreciable quantities of this compound to the watershed. Acid mine water drainage is a form of

pollution which may contribute extremely large amounts of sulfate content to natural waters. Other sources of sulfate

include waste material from pulp mills, steel mills, food processing operations and municipal wastes. Many bacteria obtain

sulfur from sulfate for the synthesis of amino acids. In lakes and streams low in oxygen, this process of sulfate reduction

causes the production of hydrogen sulfide, with its characteristic offensive odor. Calcium sulfate and magnesium sulfate

contribute significantly to the hardness of water. Under natural conditions, the quantities ordinarily to be expected in lakes

are between 3 and 30 parts per million.

APPLICATION:

Drinking and surface waters, domestic and industrial wastes.

RANGE:

0 – 100 ppm Sulfate

METHOD:

Sulfate ion is precipitated in an acid medium with barium chloride to form a barium sulfate

suspension in proportion to the amount of sulfate present.

SAMPLE HANDLING

& PRESERVATION:

Sulfate samples may be preserved by refrigeration at 4°C up to 7 days in glass or plastic

containers without any change in concentration.

INTERFERENCE:

Suspended matter and color interference may be removed by a filtration step. Silica in excess

of 500 mg/L will interfere.