Novel Approach to Automated Flow Titration for the Determination of Fe(III).

Joanna Kozak,Marta Duracz,Paweł Kościelniak,Justyna Paluch,Marek Kozak,Marcin Wieczorek

doi:10.3390/molecules25071533

Abstract

A novel approach to automated flow titration with spectrophotometric detection for the determination of Fe(III) is presented. The approach is based on the possibility of strict and simultaneous control of the flow rates of sample and titrant streams over time. It consists of creating different but precisely defined concentration gradients of titrant and analyte in each successively formed monosegments, and is based on using the calculated titrant dilution factor. The procedure was verified by complexometric titration of Fe(III) in the form of a complex with sulfosalicylic acid, using EDTA as a titrant. Fe(III) and Fe(II) (after oxidation to Fe(III) with the use of H2O2) were determined with good precision (CV lower than 1.7%, n = 6) and accuracy ( lower than 3.3%). The approach was applied to determine Fe(III) and Fe(II) in artesian water samples. Results of determinations were consistent with values obtained using the ICP–OES reference method. Using the procedure, it was possible to perform titration in 6 min for a wide range of analyte concentrations, using 2.4 mL of both sample and titrant.

Highlights

Techniques of flow analysis offer many possibilities of automation of analytical methods, including titration analysis
Using flow-based systems, titration has been performed based on the conventional procedure [1,2,3,4,5,6,7], and many novel approaches have been developed for its implementation [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35]
The analyte concentration was determined based on analytical calibration [9,10] or on the relationship between the time necessary to achieve the endpoint of titration and the flow rate of the titrant measured at the endpoint of titration [11]

Summary

Introduction

Techniques of flow analysis offer many possibilities of automation of analytical methods, including titration analysis. Using flow-based systems, titration has been performed based on the conventional procedure [1,2,3,4,5,6,7], and many novel approaches have been developed for its implementation [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35] They differ in terms of the way of introducing the sample into the flow system, merging it with the titrant solution to create an analyte concentration gradient, and, the way of determining the analyte concentration.

Methods

Findings

Discussion

Conclusion