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-j ��c: e- �.r -.� d'�� v. es,. s �t �r.._•-: 'fi;§�� „� '�°= �?' -v��:..,�,.c,. t �--'?i.-'�. t' �.:�'. '.�1.;. t-v nt,i. i �.�. .vs ,:r Vit.. ..: nfi. a s3 3 s NITROGENS NITRATE APPENDIX Ld Lala Rnnge. ".a mg!!_ Page o1z Cndmlum R Wuctlon Method Using Nitrel -r S Nitrate Reagent For Water and Wastewater Introduction Nitrate represents the most completely oxidized state of nitrogen commonly found in water.Nitrate-forming bacteria convert nitrites into nitrates under aerobic conditions and lightning converts large rmounts of at- mosphcdc nitrogen(NO dimcdy to nitrates.Many granular commercial fertilizers contain nitrogen in the form Of nitrates. High levels of nitrate in water indicate biological wastes in the final stages of stabilization or tun-off from heav- By fertilized fields. NWate-rich effluents discharged into receiving wstets can degrade water quality by en- couraging excessive growth of algae.Drinking waters containing excessive amounts of nitrates can cause infant methemoglobinernia(blue babies).For this reason,a level of 10 m&tL.nitratc nitrogen has been established as the maximum allowable concentration of nitrates in public drinking water supplies. The method of analysis used in the high range test is a modification of the cadmium reduction method using gen- tisic acid in place of 1-naphthylamine.The test registers both nitrates and nitrites present in the water sample and eliminates the need for dilutions by operating in the most useful range.All the necessary reagents have been combined into a single stable powder called NitraVer*S Nitrate Reagent. The low range nitrate test is also a modification of the cadmium reduction method using a very sensitive chromotropic acid indicator.This method registers both nitrates and nitrite nitrogen.A procedure is given in Note G for compensating for unusually high concentrations of nitrite nitrogen in the sample. A Standard Nitrate Nitrogen Solution, 10 mg/Las N,is available from Hach for checking the accuracy of the e `t test.A procedure detailing the use of the Voluette's Analytical Standards System of standard additions is given j in Note L K ARNING Some of the chemicals used in�ihis procedure may be hazardous to the health and safety of rhe user ifinappmpriatelyhandled oraccidentally misused.Pleaseread all warnings on the reagent labels and read the safety section of this manual.Ifyou have questions or would like a reprint of the safety section,please contact Hach.In the procedure,hazardous substances appear in italic typeface wherevertheyare used in the test and deserve extra care in handling.ltisalwaysgood practice to wear safety glasses when handling chemicals. Wash thoroughly ifcontact occurs. Follow instructions carefully. Sampling and Storage Collect samples in clean plastic or glass bottles.Store at 4°C(39T)or lower if the sample is to be analyzed with- in 24 hours.Warm to room temperature before running the test.For longer sttnage periods,add 2.0 mL of Sul- g funic Acid,ACS, for each liter(or quart)of sample taken using a glass serological pipet and pipet filter.Mix. t Check the sample pH to be sun-the pH is 2 or less.Add more acid if necessary.Store the samplc at 4°C(39°1:)or below. pH Adjustment r. Before testing.warm to room temperature and adjust the acidified sample to pH 7 by adding Sodium Hydroxide Standard Solution.5.ON. and mixing thoroughly.Do not use mercury compounds as preservatives.Where sig- nificant amounts of preservatives ase used,a volume correction should be made for the extra acid and base by dividing the total volume(sample +acid + base)by the sample volume and multiplying the result limes the —final test reading.— ------ — a -- -----— ----- --— ------- - -— — -- s