Simultaneous determination of nitrite, nitrate, sulphate and phenolic compounds, by sequential injection analysis, in wastewaters

A sequential injection analysis (SIA) system for the simultaneous determination of nitrite, nitrate, sulphate and phenolic compounds, in wastewaters has been developed. The nitrite determination is based on the Griess-Llosvay reaction. Nitrate is previously reduced to nitrite in a copperized cadmium column and analyzed as nitrite. The sulphate determination is based on the turbidimetric determination using barium chloride as reagent. The phenolic compounds determination is based on oxidative coupling with 4-aminoantipyrine (4-AAP) in alkaline solution. The resulting products of each reaction were spectrophotometrically measured at 540 nm. The proposed system is fully automatized and is able to monitor nitrite, nitrate, sulphate and phenolic compounds, simultaneously, in samples at a frequency of about 12 samples per hour with a relative standard deviation (RSD) better than 2.0 %, 0.7 %, 1.5 % and 2.2 %, respectively. The calibration graph is linear between 0.05 and 25 mg.dm$^{-3}$ for nitrite, 0.05 and 15 mg.dm$^{-3}$ for nitrate, 5 and 200 mg.dm$^{-3}$ for sulphate and, finally, between 0.5 and 25 mg.dm$^{-3}$ for phenolic compounds

Construction and evaluation of a crystalline silver double-membrane tubular potentiometric detector for flow injection analysis. Application to chloride determination in wine

This paper describes the construction and assessment of the operating characteristics and analytical usefulness of a homogeneous crystalline silver double membrane tubular electrode with increased sensitivity. The constructed electrodes allowed Ag(I) determinations in the $3\ 10^{-5}{-}1\ 10^{-1}$ M range with a calibration slope of 114 mV dec$^{-1}$ and with good reproducibility (0.6 mV). The development and application of a flow injection analysis system manifold for chloride determinations in wine samples, in a wide concentration range ($10 {-} 800$ mg L$^{-1}$), with a titrant consumption of 90 $\mu$g determination-1 is also described. The results obtained from the analysis of 12 wine samples showed good agreement between the proposed method and the refer-ence one, accomplishing $90 {-} 200$ samples h$^{-1}

A FIA procedure for enzymatic determination of high glucose concentrations. Application to parenteral solutions analysis

A flow injection system for the determination of high levels of glucose in parenteral solutions based on amperometric detection of hydrogen peroxide produced in the glucose oxidase reaction was developed. The determinations were made without any sample pre-treatment. The flow injection manifold includes two dialysis units to perform dilution of the samples and to maintain the enzyme in a closed re-circulation loop. Due to the hydrodynamic characteristics of the analytical system, the variables were optimized using a parameter design of Taguchi. Under optimal conditions, a linear response for glucose concentrations, between 0.1 and 1.0 M was achieved. A good reproducibility (r.s.d. $< 3\%$) and a sampling rate of 30 determinations/hour were observed. The results obtained are in a good agreement with those obtained using the spectrophotometric enzymatic method

Sampling Strategies In Sequential Injection Analysis: Exploiting The Monosegmented-flow Approach

An evaluation of different sampling techniques employing sequential injection analysis (SIA) is described. The reaction between Fe(II) and 1,10-phenanthroline, which needs a pH adjustment with acetate buffer and a prior reduction with hydroxylamine solution, was employed. As a general rule, sensitivity, compared to that of the usual SIA technique, can be enhanced with binary sampling, sandwich sampling and monosegmented flow, in that order. Under the employed conditions, signals 13, 31 and 58% higher than those provided by conventional SIA can be obtained with the binary, sandwich and monosegmented sampling, respectively. The monosegmented-flow approach was applied in determining iron in natural waters and results do not differ significantly from those obtained by ICP/AES at the 95% confidence level. The precision was 1.1%, expressed as relative standard deviation obtained by the measurement of nine replicates of 1.0mgl-1 Fe(III) reference solution. Copyright (C) 1998 Elsevier Science B.V.3661-3257262Skeggs, L.T., (1957) Am. J. Clin. Pathol., 28, p. 311Ruzicka, J., Hansen, E.H., (1975) Anal. Chim. Acta, 78, p. 145Pasquini, C., Oliveira, W.A., (1985) Anal. Chem., 57, p. 2575Karlberg, B., Thelander, S., (1978) Anal. Chim. Acta, 98, p. 1Bergamin F, H., Reis, B.F., Jacintho, A.O., Zagatto, E.A.G., (1980) Anal. Chim. Acta, 117, p. 81Olsen, O., Pessenda, L.C.R., Ruzicka, J., Hansen, E.H., (1984) Analyst, 108, p. 905Zagatto, E.A.G., Reis, B.F., Bergamin F, H., Krug, F.J., (1979) Anal. Chim. Acta, 109, p. 41Faria, L.C., Pasquini, C., (1987) Anal. Chim. Acta, 193, p. 19Reis, B.F., Jacintho, A.O., Mortatti, J., Krug, F.J., Zagatto, E.A.G., Bergamin F, H., Pessenda, L.C.R., (1981) Anal. Chim. Acta, 123, p. 221Ruzicka, J., Marshall, G.D., (1990) Anal. Chim. Acta, 237, p. 329Reis, B.F., Giné, M.F., Zagatto, E.A.G., Lima, J.L.F.C., Lapa, R.A., (1994) Anal. Chim. Acta, 293, p. 129Cladera, A., Torrias, C., Gómez, E., Estela, J.M., Cerdá, V., (1995) Anal. Chim. Acta, 302, p. 297Raimundo I.M., Jr., Pasquini, C., (1997) Analyst, 122, p. 103