Nitrate – LaMotte SMART Spectro Spectrophotometer User Manual

Page 190

NITRATE

ZINC REDUCTION TESTAB METHOD • CODE 3689-SC

QUANTITY

CONTENTS

CODE

*Nitrate Spectrophotometic Grade Tablets

*3881A-H

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:

2.5 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.

SMART Spectro Test Procedures 2.11

NITRATE, TesTab

Test P

rocedures