Determination of nitrate and nitrite by forced-flow liquid chromatography with electrochemical detection

Abstract

The determination of N03~a nd N02~by forced-flow liquid chromatography with a Cd tubular detector is described. Dissolved 02, N03~, and N02~w ere separated with Amberlite IRA-900, a strongly basic anion-exchange resin. The eluent was 0.010M HCIO4, and the time required for the analysis was 7-9 min. The areas of the chromatographic peaks for N03~a nd N02~w ere proportional to concentration over the working range of 0.05-1.0 m (0.7-14 ppm N) In a 0.33-ml sample. The detection limit was approximately 0.01mM (0.1 ppm N). A Cd coulometric detector was used to demonstrate that both N03_ and N02_ are electrochemically reduced to NH2OH in acidic media. Nitrate was rapidly reduced to N02_, and N02~m ore slowly reduced to NH2OH at a rotating Cd disk electrode.

Electrochemical determination of nitrites in natural waters with ultramicroelectrodes

“…The detection limit, calculated as already discussed, was 2.98 pM for aerated solutions, lower than those obtained in the previous section and more adequate to detection of contamination with nitrite in potable water (whose allowed superior concentration limit is 4pM [4]). Nevertheless, the effect of interferents in that detection limit has to be carefully analyzed.…”

“…With faster reaction rates, the measured signal of a given nitrite concentration is more intense and, consequently, the detection limit diminishes. Such arguments were The detection limits calculated in sulfate solutions have a value slightly lower than those reported as the superior limit expected to be found in potable water [4]. In this sense, the methodology developed here is convenient for contamination monitoring.…”

“…Fatal doses have been recorded as 0.4-1.3mgL-' [2] but the mean lethal dose for adults is probably about 1 gram, if administered at one time [3]. The allowable residue of nitrite in potable water is 4 p M [4].…”

Voltammetric Determination of Nitrates Using Silver Electrodes

“…Cadmium appeared to be a more suitable electrode material, the measurements carried out with a cadmium rotating disk electrode gave a well-developed signal corresponding to the reduction of nitrates. The calibration plot was linear, however, only in a very narrow concentration range [6]. Cadmium deposited on the surface of graphite or gold electrodes also appeared to be a suitable electrode material for the electrochemical reduction of nitrate ions [18,19].…”

Tubular electrodes in flow injection analysis

“…In the past, points 1 through 4 were recognized as limitations of the steady-state equation (3,32) and were readily apparent when the steadystate equation was compared to experimental results. Point 5…”