Sequential injections as an alternative to gradient exploitation for implementing differential kinetic analysis in a...

Area of Science:

• Analytical Chemistry
• Spectrophotometry
• Flow Injection Analysis

Background:

• Simultaneous determination of multiple analytes reacting with the same reagents is challenging.
• Catalytic spectrophotometric methods offer sensitive detection but often lack selectivity.
• Iron and vanadium determination is crucial for alloy characterization.

Purpose of the Study:

• To develop a novel flow-based strategy for simultaneous spectrophotometric determination of iron and vanadium.
• To apply this method to Fe-V alloys using catalytic reactions.
• To validate the proposed method against a standard technique.

Main Methods:

• A flow-based system was designed for sequential sample injection into reagent streams.
• The method utilizes the differential catalytic effect of Fe(II) and V(IV) on iodide oxidation by Cr(VI).
• Multivariate calibration using the Partial Least Squares (PLS) algorithm was employed for data analysis.

Main Results:

• The flow system generated complex sample zones with distinct absorbance regions.
• Precise measurements were achieved by analyzing these absorbance extrema.
• The method demonstrated high analytical information content (ca. 95% with two latent variables).

Conclusions:

• The proposed flow-based strategy enables simple, rugged, and simultaneous determination of iron and vanadium.
• Results obtained were in excellent agreement with Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES).
• This method offers a sensitive and selective approach for analyzing Fe-V alloys.