Determination of gallic acid with rhodanine by reverse flow injection analysis using simplex optimization.

Area of Science:

• Analytical Chemistry
• Food Chemistry
• Spectrophotometry

Background:

• Gallic acid is a significant phenolic compound with various health benefits.
• Accurate determination of gallic acid is crucial for quality control in food products.
• Existing methods may lack selectivity or require complex sample preparation.

Purpose of the Study:

• To develop and validate a novel reversed flow injection (rFI) system for gallic acid determination.
• To optimize experimental conditions for enhanced sensitivity and selectivity.
• To assess the method's applicability to real-world samples like longan.

Main Methods:

• Design and construction of a reversed flow injection system.
• Colorimetric detection based on the reaction between gallic acid and rhodanine.
• Optimization of reaction and flow parameters using univariate and multivariate methods.
• Validation of the method's linearity, detection limit, and precision.
• Application to gallic acid determination in longan samples.

Main Results:

• The rFI system achieved gallic acid determination at λmax 520 nm.
• Optimized conditions yielded high selectivity and precision.
• Linearity was observed from 0.1-35.0 mg L⁻¹ with a detection limit of 0.081 mg L⁻¹.
• Relative standard deviations were below 1.96% for various concentrations.
• Successful application to longan samples without interference from other phenolic compounds.

Conclusions:

• The developed rFI method provides a simple, highly selective, and precise approach for gallic acid quantification.
• The method is suitable for routine analysis of gallic acid in complex matrices.
• This technique offers a valuable tool for food quality assessment and research.