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<br />w <br />o <br />o <br /> <br />Sulfate was measured by using a Bach Field Test Kit. <br /> <br />- <br /> <br />Colorimetric methods were utilized in all other chemical tests using <br /> <br />Bausch & Lomb standard model "Spectronic 20" spectrophotometer. <br /> <br />Ammonia concentrations were determined by direct Nesslerization. Errors <br /> <br />brought about by higb turbidity levels were negated by determining ~~e optical <br /> <br />density (G.D.) of the sample before and after Nesslerization process. Deionized <br /> <br />water was used to "zero" the "spec 20" for the D.D. measurement prior to <br /> <br />Nesslerization and a procedural blank was utilized for the same purpose before <br /> <br />measuring the treated samples. The D.D. prior to Nesslerization is subtracted <br /> <br />from the D.D. after treatment. The corrected figure is then translated into <br /> <br />terms of mg NH3/L. <br /> <br />Nitrite determinations were performed using the sul=anilic acid, naphthylar.dne <br /> <br />hydrochloride method. Photometric compensation is used to negate hig.~ readings <br /> <br />due to turbidity. The methodology is identical to the process described in the <br /> <br />preceeding paragraph for a~nia. <br /> <br />NitratE ddterminations were performed by evaporating 2S ml of sample, then <br /> <br />phenodisulfonic acid treat:nent and pH adjustments ...ith sodium hydroxide. The <br /> <br />resulting sample was read on the Spec 20. <br /> <br />Orthophosphate was determined by the 1 amino, 2 naphtlUJI, 4 sulfonic acid <br /> <br />(A.~S) method. ~~rbidity references were cancelled by testing a second aliquot <br /> <br />of sample but substituting a strong acid for the a~ni~ molybdate solution. <br /> <br />Total phosphate was deter:nined by t.':1.e above !:Jet-iod after fuming wit.'l <br /> <br />nitric and sulfuric acid. <br /> <br />T.ie "Spec 20" was "zeroed" on each sample rat.her tJ:ta:l a procedural blank <br /> <br />of deionized water. <br />