COMPARISONS OF MERCURY(2) CHLORIDE AND SULFURIC ACID AS PRESERVATIVES FOR NITROGEN FORMS IN WATER SAMPLES

Ammonia, organic nitrite, and nitrate nitrogen forms in surface water samples underwent biological changes which were more effectively prevented by addition of 42 mg. of mercury(II) chloride per liter of sample than by 0.8 ml. of concentrated sulfuric acid. Sulfuric acid was particularly unsuitable for preserving samples containing nitrite or a mixture of nitrite and nitrate because it caused the chemical conversion of nitrite to nitrate. Addition of 42 mg. per liter of mercury(II) chloride did not interfere with analytical procedures employed. However, 80 mg. per liter of mercury(II) chloride lowered distillation recoveries of free ammonia from distilled water. © 1969, American Chemical Society. All rights reserved.