Flow injection sample-to-standard additions method. Spectrophotometric determination of hydrochloric acid and orthophosphate

Abstract

Conventional flow injection (FI) has been utilised for the development of the sample-to-standard additions method as an alternative to the reverse FI standard additions method. An equation has been derived for the proposed method, allowing the calculation of sample concentration from two transient signals obtained from the injection of the sample solution and the blank, which must possess matched matrix composition. For these conditions the sample-to-standard additions method was as effective as the standard additions method. Two conventional FI methods for the determination of hydrochloric acid and orthophosphate in phosphate rock digests were examined by the sample-to-standard additions method. Satisfactorily accurate and precise results were demonstrated. Because the proposed method was operated in the conventional FI mode, an autosampler was incorporated to obtain a throughput of 80-100 samples h-1.

Simultaneous multiple injection to perform titration and standard addition in mono-segmented flow analysis

“…Recently, Campõ¨ns-Falco¨et al [48] compared the performance of diå erent approaches [35, 36, 38± 40] for standard addition in FIA and Lavilla et al [49] studied the applicability of the method proposed by Israel and Barnes [39] with and without the use of a matrixmatched blank for determination of metals in sewage sludge.…”

“…In 1989, Israel and Barnes [39] developed a sample-tostandard addition method also based on two injections, blank and sample, which showed the disadvantag e of matching matrix composition into standard carrier composition. Beuchemin [40] employed a variation of the method proposed by Israel and Barnes [39] for ICP-MS.…”

“…Beuchemin [40] employed a variation of the method proposed by Israel and Barnes [39] for ICP-MS. The concentrations of the samples were determined by means of three injections, that is, injection of the sample into a standard blank solution and into a standard (with concentration higher than the sample) carrier solution, and injection of the standard into the blank carrier stream.…”

“…Since the procedures are usually time consuming, a great deal of attention has been paid to develop standard addition¯ow systems, which allow speeding up the analysis [32± 47]. Three diå erent approaches have been employed to perform standard addition in¯ow systems, based on the continuous pumping of sample (reversed FIA) [32± 37], continuous pumping of the standard (conventional FIA) [38,39] or on the merging zone process [40± 44].…”

An automatic flow-batch standard-addition method for sodium determination in alcohol fuel by flame photometry

“…Such problems have been circumvented by using automated flow systems. [7][8][9][10][11][12][13][14][15][16][17][18][19] Versatile and flexible flow-batch approaches [20][21][22][23] have been proposed to automate some analytical systems, as developed by our research group. The flow-batch systems use three-way solenoids valves and an open mixing chamber and are characterised to combine the intrinsic favorable features of both the flow and batch techniques and to provide very good analytical figures of merit.…”