Over-the-counter (OTC) pharmaceutical formulations, including those for cough suppression and pain relief, contain inactive ingredients which are glycols, sugar alcohols, and other carbohydrates such as glucose and sucrose. They are used for imparting consistency as well as masking unpleasant tastes originating from other compounds in the formulation. Inactive ingredients can sometimes cause adverse effects and thus amounts of these ingredients in the formulation must be known. For example, some carbohydrates can cause digestion issues. Carbohydrates are non-chromophoric and cannot be detected by spectrophotometry. They can be oxidized and thus detected and quantified using pulsed amperometric detection (PAD). This detection method is specific for those analytes that can be oxidized at the selected potential, leaving all other non-oxidizable compounds undetected. Pulsed amperometric detection is a powerful detection technique with a broad linear range and very low detection limits.<br/><br/>High-performance anion-exchange chromatography (HPAE) is a well-established method for separation of carbohydrates. When hyphenated with PAD (HPAE-PAD), this approach offers a high resolution, high sensitivity method for determination of monosaccharides, sialic acids, and other carbohydrates. It allows for direct detection and hence no sample derivatization is required.<br/><br/>Here we present a convenient, fast, and sensitive HPAE-PAD method to determine carbohydrates in pharmaceutical formulations. This method uses a recently released column for carbohydrate separation that has a different selectivity from earlier columns, and electrolytic eluent generation. This eluent generation eliminates the need to make eluents and the errors associated with eluent preparation.The new column is packed with a new supermacroporous resin with 4 µm particle size to achieve high efficiency and high-resolution separations. Using this column, a 16.8 min method (Figure 1) that resolved six analytes which included glycols and other carbohydrates was designed. Results for method linearity, robustness, and accuracy for glycol and carbohydrate quantification in OTC samples are discussed.

Fast HPAE-PAD method for determination of carbohydrates and glycols in pharmaceutical formulations

ACS Spring 2022

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