Deveropment of a continuous monitoring system for an acid rain based on null-point potentiometry

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(1) A new buffer based on glycine/HCL pH2.80 was proposed for the determination of very low concentrations of free-fluoride in eain water, by using the continuous-flow analysis system with a fluoride ion-selective electrode detector. (2) A new nitrate ion-selective electrode based on his (bathocuproin) copper (II) nitrate ion-exchanger was developed and applied to the time-course observation of nitrate concectration in an acid rain by using the continuous-flow analysis system. (3) A novel continuous-flow analysis system for nitrate in an acid rain was developed, which is based on null-point potentiometry. In this sytem, a nitrate ion-selective membrane based on triotadecylmethylammonium nitrate ion-exchanger was used as a detector. The membrane potential between the sample and standard sides was kept automatically so as to be (]sy.+-.[)1 mV by controlling the dilution rate of a standard KNO3 solution. The concentration of a sample solution is displayd 5-10min after its injection into the flow system. The accuracy and precision of the independent five measurements were within about 5%. This system was applied to rain water analysis.