LaMotte SMART3 Colorimeter - Manual (Page 213)

NITRATE
ZINC REDUCTION · CODE 3689-SC
QUANTITY CONTENTS CODE
50 *Nitrate Spectrophotometric Grade Tablets *3881A-H
1 Tablet Crusher 0175
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents go
to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail, phone or
fax.
Nitrogen is essential for plant growth, but excessive amounts in water supplies can
result in nutrient pollution. Nitrates, in conjunction with phosphate, stimulate the
growth of algae creating water quality problems. Nitrogen compounds may enter
water as nitrates or be converted to nitrates from agricultural fertilizers, sewage,
industrial and packing house wastes, drainage from livestock feeding areas
and manure. Nitrates in large amounts in drinking water can cause “blue baby
syndrome” (methemoglobenemia) in infants in less than 6 months of age and other
health problems. US Public Health Service Drinking Water Standards state that
44 ppm nitrate should not be exceeded. To the sanitary and industrial engineer,
concentrations of less than 4 ppm are acceptable.
APPLICATION: Drinking, surface, and saline waters; domestic and
industrial waters.
RANGE: 0–60 ppm Nitrate
MDL: 5 ppm
METHOD: Zinc is used to reduce nitrate to nitrite. The nitrite
that was originally present, plus the reduced nitrate,
reacts with chromotropic acid to form a red color in
proportion to the amount of nitrite in the sample.
SAMPLE HANDLING &
PRESERVATION:
Analysis should be made as soon as possible. If
analysis cannot be made within 24 hours, the sample
should be refrigerated at 4°C. When samples must
be stored for more than 24 hours, add 2 mL of
concentrated sulfuric acid per liter of sample. For best
results, the analysis for nitrate should be determined
at temperatures between 20°C and 25°C.
INTERFERENCES: Nitrite interferes at all concentrations. Strong oxidizing
and reducing substances interfere. Low results
might be obtained for samples that contain high
concentrations of copper and iron.
SMART3 Test Procedures 2.11 NITRATE, Tablet
Test P
rocedures