Sampling strategies in sequential injection analysis: Exploiting the monosegmented-flow approach

• Published in: Analytica chimica acta 1998-06, Vol.366 (1), p.257-262
• Main Authors: Vieira, Jonas A, Raimundo, Jr, Ivo M, Reis, Boaventura F, Zagatto, Elias A.G, Lima, José L.F.C
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Applied sciences; Binary sampling; Chemistry; Continental surface waters; Exact sciences and technology; Monosegmented flow; Natural water pollution; Pollution; Sampling techniques; Sequential injection; Spectrometric and optical methods; Water treatment and pollution
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/S0003-2670(98)00113-5

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 1.0 mg l −1 Fe(III) reference solution.