Stopped-in-loop flow analysis system for successive determination of trace vanadium and iron in drinking water using their catalytic reactions☆

Advanced Stopped-in-Loop Flow Analysis with a Reagents-Merging Zones Technique for a Catalytic Successive Determination of Vanadium and Iron

“…The RSD values (n = 5) of the present work were 2.4% for 5 μg L -1 vanadium and 2.8% for 50 μg L -1 iron, respectively. The repeatability was comparable to that of the previous SILFA method, 23 whose RSD values (n = 5) were 2.2 for 1 μg L -1 vanadium and 2.3% for 10 μg L -1 iron, respectively. However, the sensitivities of the proposed method for the successive determination of vanadium and iron were better than those of a catalytic spectrophotometric method for the simultaneous determination of mg L -1 levels of vanadium and iron.…”

“…In the presence of 0.015 mol L -1 diphosphate in the RS1, 400 μg L -1 iron was tolerable for the determination of 1 μg L -1 vanadium. for vanadium, 2.20 μg L -1 for iron) were higher than those obtained with previous FIA methods (e.g., 0.01 μg L -1 for vanadium 9 and 0.05 μg L -1 for iron 13 ) and with a previous SILFA method 23 (0.052 μg L -1 for vanadium and 0.55 μg L -1 for iron). The RSD values (n = 5) of the present work were 2.4% for 5 μg L -1 vanadium and 2.8% for 50 μg L -1 iron, respectively.…”

“…When a standard/sample solution was replaced with another standard/ sample solution, the sampling tubing connected to the SWV1 was washed by the aspiration of an appropriate volume of another solution and sent to the waste. The same heater device described in a previous paper 23 was used for heating the reaction solution filled in the loop. Spectrophotometric measurements were made using an Ocean Optics USB2000 UV-VIS detector equipped with a z-shaped flow-through cell (28 μL, 15 mm path length).…”

“…However, the number of papers on flow injection spectrophotometry for the simultaneous/successive determination of two different metal ions (including two oxidation states of a metal) in the same sample is limited. For instance, binary mixtures of iron(III)/vanadium(V), 18 iron(III)/chromium(VI), 18 and vanadium(IV)/vanadium(V), 19 were selectively determined using the redox reactions, and also catalytic methods for iron/ copper 20,21 and vanadium/iron 22,23 were proposed. In recent years, our research group has proposed alternative concepts for flow injection analysis (FIA) systems, called stopped-in-loop flow analysis (SILFA) 24 and stopped-in-dualloop flow analysis (SIDLFA) 25 to reduce reagent consumption compared with conventional FIA.…”

“…Furthermore, a simultaneous injection effective mixing flow analysis (SIEMA) system having advantages in terms of simple automation, rapid analysis and high sensitivity was proposed. [26][27][28] In a previous study, 23 the SILFA concept was applied to the successive catalytic determination of vanadium and iron in water samples, developing an automated system with better analytical performance compared with the results obtained with conventional FIA systems. However, the SILFA concept still has a drawback, i.e., when reagent(s) and sample solutions are loaded into the stopped-in-loop, a part of the solution is discarded into a waste bottle in order to exchange the solution inside the loop with the newly loaded solution completely.…”