TY - JOUR
T1 - Determination of Nitrate Ion at the Part per Billion Level in Environmental Samples with a Continuous Flow Immobilized Enzyme Reaction
AU - Senn, David R.
AU - Carr, Peter W.
AU - Klatt, Leon N.
PY - 1976/6/1
Y1 - 1976/6/1
N2 - A sensitive procedure for the determination of nitrate based upon the enzymatic reduction of nitrate to nitrite is described, The radical cation of 1,1′-dimethyl-4,4′-bipyridinium dichloride (MV·+), which is generated by Na2S2O4 acting upon MV2+, reduces nitrate in the presence of the enzyme nitrate reductase. The production of nitrite is monitored with the sulfanilamide N-(1-naphthyl)ethylenediamine dichloride azo dye reaction. A detection limit of 17 ppb NO3- using a 1-cm cell in a continuous-flow analyzer was achieved. The major contributor to the noise was derived from the flow system when an optical feedback stabilized photometer was employed. The detection limit using a nonflow system should be about 2 ppb NO3- using a 1-cm cell. Use of an immobilized enzyme resulted in quantitative reduction of nitrate and the method is, therefore, relatively free of interferences. Sample concentrations in the range 17 ppb to 7 ppm NO3- can be measured. At a concentration of 0.2 ppm, a precision of 1 % can be obtained in a continuous flow analyzer. A variety of real samples were analyzed; correlation with the accepted Cu-Cd reductor method was excellent.
AB - A sensitive procedure for the determination of nitrate based upon the enzymatic reduction of nitrate to nitrite is described, The radical cation of 1,1′-dimethyl-4,4′-bipyridinium dichloride (MV·+), which is generated by Na2S2O4 acting upon MV2+, reduces nitrate in the presence of the enzyme nitrate reductase. The production of nitrite is monitored with the sulfanilamide N-(1-naphthyl)ethylenediamine dichloride azo dye reaction. A detection limit of 17 ppb NO3- using a 1-cm cell in a continuous-flow analyzer was achieved. The major contributor to the noise was derived from the flow system when an optical feedback stabilized photometer was employed. The detection limit using a nonflow system should be about 2 ppb NO3- using a 1-cm cell. Use of an immobilized enzyme resulted in quantitative reduction of nitrate and the method is, therefore, relatively free of interferences. Sample concentrations in the range 17 ppb to 7 ppm NO3- can be measured. At a concentration of 0.2 ppm, a precision of 1 % can be obtained in a continuous flow analyzer. A variety of real samples were analyzed; correlation with the accepted Cu-Cd reductor method was excellent.
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U2 - 10.1021/ac60371a030
DO - 10.1021/ac60371a030
M3 - Article
C2 - 1267173
AN - SCOPUS:0017098862
SN - 0003-2700
VL - 48
SP - 954
EP - 958
JO - Analytical Chemistry
JF - Analytical Chemistry
IS - 7
ER -