LaMotte DC1500 SULFATE, Руководство пользователя

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6
TEST METHODS SPECIFICATIONS
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INTRODUCTION
The most common mineral forms of sulfur are iron sulfide, lead sulfide, zinc
sulfide, 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.
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APPLICATION
Drinking and surface; domestic and industrial wastes.
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RANGE
0 to 100 ppm Sulfate
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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.
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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.
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INTERFERENCES
Suspended matter and color interference may be removed by a filtration step.
Silica in excess of 500 mg/L will interfere.