Determination of Benzoate in Liquid Food Products by Reagent-Free™ Ion Chromatography

Importance of the Topic

Food and beverage preservation is critical for safety and shelf-life, and benzoate is among the most widely used preservatives due to its antimicrobial properties at low pH and favorable toxicity profile. Accurate quantification of benzoate ensures regulatory compliance and product quality across soft drinks, fruit juices, condiments, and other liquid foods.

Objectives and Study Overview

This study aimed to develop and validate a reagent-free ion chromatography method for direct determination of benzoate in liquid food matrices. The approach leverages electrolytically generated potassium hydroxide eluent to simplify operation and minimize manual reagent handling.

Methodology and Instrumentation

The Dionex ICS-2000 RFIC System was employed, configured with an EluGen EGC II KOH cartridge, CR-ATC suppressor in AutoSuppression recycle mode, and an IonPac AG18 guard column with an IonPac AS18 analytical column (4×50 mm and 4×250 mm). Eluent gradients from 35 to 40 mM KOH at 1.0 mL/min, 30 °C, and suppressed conductivity detection enabled separation. Samples (carbonated or high-ionic strength) were degassed and diluted (1:20–1:100) in deionized water prior to analysis.

Main Results and Discussion

Calibration over 1–20 mg/L benzoate showed excellent linearity (r2=0.9998) with a method detection limit of 4.9 μg/L. Four products (flavored soda, diet soda, soy sauce, lemon juice) containing labeled benzoate were analyzed. Resulting benzoate concentrations (0.019–0.051%) were below the 0.1% FDA limit. Retention time RSDs were <0.06% and peak area RSDs <0.5%. Spike recoveries ranged 90–101%, confirming method accuracy.

Benefits and Practical Applications

• Reagent-free eluent generation reduces preparation errors and waste.
• Direct injection of diluted samples accelerates throughput.
• High capacity AS18 column tolerates chloride and citrate interferences.
• Robust precision and low detection limits suit QC laboratories.

Future Trends and Potential Applications

Advances may include multi-analyte profiling of preservatives, coupling RFIC with mass spectrometry for confirmatory analysis, further miniaturization for on-site testing, and automated online sample preparation to enhance throughput in industrial QC settings.

Conclusion

The RFIC method offers a streamlined, accurate, and reproducible approach for benzoate determination in diverse liquid food products. Its reagent-free operation, simple sample preparation, and robust performance make it ideal for routine quality control and regulatory monitoring.

Reference

• Velsicol Chemical Corporation. Sodium Benzoate Food Grade, FCC; Product Information Bulletin.
• World Health Organization. Benzoic Acid and Sodium Benzoate, Concise International Chemical Assessment Document No. 26, 2000.
• National Soft Drink Association. About Soft Drinks, 2003.
• U.S. Food and Drug Administration. Code of Federal Regulations Title 21, §582.3733 Sodium Benzoate, 2003.
• European Parliament and Council Directive 95/2/EC on Food Additives, 1995.
• Pezza L. et al. Anal. Chim. Acta 2001, 433, 281–288.
• Association of Official Analytical Chemists. Method 983.16, Determination of Benzoic and Sorbic Acids in Food, 1995.