Critical approach to flow injection gradient titration as a calibration method.

Area of Science:

• Analytical Chemistry
• Spectrophotometry

Background:

• Classical titration methods are well-established in quantitative analysis.
• Flow injection analysis (FIA) offers rapid sample throughput.
• Differentiating titration techniques is crucial for accurate chemical quantification.

Purpose of the Study:

• To demonstrate that flow injection gradient titration functions as an indirect calibration method.
• To differentiate flow injection gradient titration from classical titration procedures.
• To present the analytical performance of a developed indirect calibration procedure.

Main Methods:

• Indirect spectrophotometric determination of chlorite ions using the Fe(II)/o-phenanthroline complex.
• Employing a flow injection system with a large-volume sample loop instead of a mixing chamber.
• Measuring absorbance at 512nm to quantify the colored complex and analyzing peak widths as the analytical signal.

Main Results:

• Experimental evidence showed flow injection gradient titration aligns with indirect calibration principles.
• The developed method yielded characteristic cut-off profile peaks with two equivalence points.
• Peak widths were successfully utilized as the analytical signal for chlorite ion determination.

Conclusions:

• Flow injection gradient titration should be classified as an indirect calibration method.
• The distinction from classical titration is primarily technical, related to system configuration.
• The developed indirect calibration procedure demonstrates viable analytical performance for chlorite ion quantification.