Determination of Aluminum in OTC Pharmaceutical Products

Importance of the Topic

Aluminum is a prevalent element in over-the-counter (OTC) antacid and antiperspirant products. Accurate measurement of aluminum content is critical for ensuring consumer safety, regulatory compliance, and consistent product performance.

Objective and Study Overview

This study aimed to develop and validate a rapid ion chromatography (IC) method with postcolumn derivatization using Tiron and UV absorbance detection for quantifying Al³⁺ in OTC formulations, specifically antacid suspensions and solid antiperspirant sticks.

Methodology and Instrumentation

• Chromatographic Separation: Thermo Scientific Dionex IonPac CG10 guard column (4×50 mm) and CS10 analytical column (4×250 mm) with 0.75 M HCl eluent at 1.36 mL/min.
• Postcolumn Derivatization: 0.3 mM Tiron reagent prepared in 3 M ammonium acetate buffer (pH ≈4.8), delivered at 0.68 mL/min through a 125 µL reaction coil.
• Detection: UV absorbance at 310 nm using a Thermo Scientific Dionex VWD detector (11 µL flow cell).
• System: Thermo Scientific Dionex ICS-5000+ HPIC with AS-AP autosampler and Chromeleon CDS software.
• Sample Preparation: Dissolution in 50 mM NaOH, sonication (30 min), 20× dilution, and filtration through 0.2 µm PES syringe filters.

Main Results and Discussion

• Column Selection: CS10 provided optimal peak shape, symmetry, and capacity compared to CS5A, CS11, and OmniPac PCX-100.
• Calibration Performance: Linear response for Al³⁺ from 1.5–30 mg/L (r² > 0.9999). LOD ~32 µg/L, LOQ ~108 µg/L, MDL ~13 µg/L.
• Accuracy and Precision: Antacid spike recoveries at 50% and 100% were 99.9% and 100%, respectively; antiperspirant recoveries ranged from 74.7% to 104% with acceptable precision (RSD <1%).
• Run Time: Total analysis time per injection ~5 min, supporting high throughput.

Benefits and Practical Applications

This IC method offers a straightforward workflow, minimal reagent consumption, and rapid detection of aluminum in diverse OTC matrices. It is well suited for routine quality control laboratories in pharmaceutical and personal care production.

Future Trends and Potential Applications

• Integration with reagent-free IC systems to further streamline maintenance and reduce reagent handling.
• Expansion to multi-element analysis by incorporating additional selective derivatization reagents.
• Automation of sample preparation steps to increase throughput and reproducibility.

Conclusion

The validated IC method with postcolumn Tiron derivatization and UV detection provides reliable, precise, and rapid quantification of aluminum in OTC antacid and antiperspirant products, meeting regulatory and quality assurance requirements.

Reference

1. Mason B. The Earth Sciences, Harper & Row, 1971.
2. Butler H. Poucher’s Perfumes, Cosmetics and Soaps, 10th Ed., Kluwer Academic Publishers, 2000.
3. Thermo Scientific Application Note 69: Determination of Aluminum in Complex Matrices Using Chelation Ion Chromatography, 1991.
4. Thermo Scientific Technical Note 26: Determination of Cr(VI) in Water, Wastewater, and Solid Waste Extracts, 2015.