Determination of Glucosamine in Dietary Supplements Using HPAE-PAD

Significance of the Topic

The accurate quantification of glucosamine in dietary supplements is essential to ensure label compliance, support joint health research, and meet regulatory quality standards. Glucosamine is a key component in cartilage structure and is widely used for osteoarthritis management and general wellness. Reliable analytical methods are needed to verify product potency, detect impurities, and uphold current good manufacturing practices.

Objectives and Study Overview

This study presents a rapid, rugged, isocratic HPAE-PAD method for direct determination of glucosamine in tablets, capsules, and fortified liquids. Key performance attributes—accuracy, precision, limits of detection and quantification, linearity, and ruggedness—were assessed. A CarboPac PA20 column with pulsed amperometric detection and an eluent generation system enabled high sample throughput and reproducible retention times.

Methodology and Instrumentation

The approach uses high-performance anion exchange with pulsed amperometric detection, eliminating the need for derivatization. Direct oxidation of amino and hydroxyl groups enables specific detection of glucosamine.

• Ion chromatography system: Thermo Scientific Dionex ICS-3000 RFIC-EG with EGC II KOH cartridge and CR-ATC trap column
• Analytical column: CarboPac PA20, 3×150 mm
• Detector: DC pulsed amperometric detector with disposable gold working electrodes and Ag/AgCl reference
• Autosampler: 10 µL injection loop, diverter valve for sample flush during analysis
• Eluent organizer and vacuum pump for degassing
• Software: Thermo Scientific Chromeleon chromatography management
• Reagents: 18 MΩ·cm water, D-glucosamine, other saccharide standards

Sample preparation involved dispersing and sonicating solid dosage forms or degassed liquids in water, centrifugation, and gravimetric dilution to a 10 µM glucosamine target.

Main Results and Discussion

Under 20 mM KOH, glucosamine eluted at ~5.0 min with no interference from methylsulfonylmethane, sorbitol, or common saccharides. Baseline dips from non-electroactive impurities and the oxygen dip at ~16 min were avoided by method conditions. The calibration was linear over 0.30–340 µM (r²>0.9999) and in the routine range of 1.8–36 µM (r²>0.9998). The limit of detection was ~0.09 µM. Over 718 injections across 5 days, retention time RSD was 0.61% and peak area RSD 1.06%. Spike recoveries in water and sample matrix were 93–102%. Seven commercial supplements showed 110–152% of label-declared glucosamine. Related compounds (glycerol, mannitol, propylene glycol, myo-inositol, glucose, fructose, sucrose) were also quantified.

Benefits and Practical Applications of the Method

• No derivatization or complex sample prep
• High throughput: >100 samples per day
• Reagent-free eluent for reproducible retention times
• Robust performance across varied matrices
• Capability to detect multiple saccharides and glycols

Future Trends and Potential Applications

Future work may extend this method to broader glyconutritional and veterinary products, integrate mass spectrometric detection for structural confirmation, automate sample handling for higher throughput, and apply similar strategies to other dietary supplement components.

Conclusion

The described HPAE-PAD method offers a sensitive, precise, and direct approach for determining glucosamine and related saccharides in dietary supplements, fulfilling regulatory and quality control requirements without derivatization.

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