Chromatography-based Quantitative Analysis of Excipient

Advances in chromatographic techniques and methods have provided scientists with innovative ways to overcome the challenges of excipient auantitative analysis, and support the production of therapeutic drugs suitable for clinical use. BOC Sciences has developed a series of systematic methods to detect and quantify ingredients in excipients in order to provide additional insights for formulation development.

Figure 1. Analytical techniques used in excipients analysis. (Kumar, M.; et al. 2018)

Our Capabilities

Analysis of the composition of pharmaceutical excipients often involves a range of chromatographic techniques to determine the molecular and chemical composition. Only by using all these techniques can a reliable determination of the composition be accomplished.

Size Exclusion Chromatography (SEC)-Infrared (IR) Spectroscopy

Excipients are pharmacologically inactive substances that act as carriers and release controllers for active pharmaceutical ingredients. A large number of polymeric excipients such as hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), hydroxypropyl methyl cellulose acetate succinate (HPMCAS) and povidone are used. These excipients have very large molecular weights and are not suitable for the commonly used LC-MS methods for drug quality control. In contrast, IR can characterize the above mentioned polymeric excipients. At BOC Sciences, our SEC technique is suitable for the separation of excipients and active ingredients based on their size, and the separated components are detected by IR.

Gel Permeation Chromatography (GPC)-Fourier Transform Infrared (FTIR) Spectroscopy

Copolymers, such as polyvinylpyrrolidone/vinyl acetate (PVP/VAc), are often used as excipients in drug formulations. These copolymers can be analyzed by a combined method of GPC and FTIR. When analyzing polymers, the eluent of the chromatographic method is deposited in the sample as a continuous track of the sample, and it varies from high molecular weight to low. The molecular structure map of all regions of a polymer GPC separation is able to be used to characterize the distribution of the monomers in the sample.

High-performance Liquid Chromatography (HLPC)-Charged Aerosol Detector (CAD)

At BOC Sciences, our experts combine HLPC and CAD for the separation and characterization of excipients. HPLC facilitates a wide range of bonding phases, particle sizes and morphologies, and column dimensions, providing a flexible and reliable method to separate complex samples. Meanwhile, CAD techniques are more sensitive and accurate than light scattering or refractive index-based methods, and easier to use than mass spectrometry. We can use CAD to detect non-volatile and semi-volatile analytes in excipients. CAD response for all non-volatiles is independent of the chemical structure of the analyte, and can be quantified using a uniform single calibrator. BOC Sciences has designed our HPLC-CAD system to effectively characterize numerous classes of excipients.

Figure 2. Schematic of charged aerosol detection (CAD) technology. (Fabel, S. 2020）

• Separation of proteins and excipients

Protein therapeutics degrade and aggregate during storage, and therefore must be mixed with amino acid excipients to stabilize, bulk and buffer the formulation. Therefore, it is critical to detect and analyze the excipients that are best suited for this function. Our HLPC-CAD technology enables the successful simultaneous isolation and detection of therapeutic proteins and amino acids. This unique system is capable of measuring compounds with chromophores (via UV) and without chromophores (via CAD), while reducing the time spent preparing samples and performing analysis.

• Measurement of the purity of adjuvant

Immunological adjuvants are substances that help improve the vaccine effectiveness by reducing the number or frequency of required doses, prolonging the duration of immunological memory, or enhancing the immune response. Quantification of adjuvant strength, purity, stability and degradation is subject to strict standards and regulations, however, many commonly used adjuvants contain components that lack the chromophores required for traditional analytical methods. CAD is capable of identifying structurally diverse compounds including saponins, cholesterol and phospholipids. By characterizing compounds with and without chromophores, our UHPLC-CAD system allows our team to measure the complete range of adjuvant species, degradation products and potential impurities with improved efficiency and sensitivity.

HPLC-Evaporative Light Scattering (ELS)

It is increasingly recognized that excipients in nanomedicines are critical in determining the product quality, stability, consistency and safety. We introduce an HPLC method that combines an ELS detector with an UV-Vis detector for the analysis of excipients in nanomedicines including nanoparticles encapsulating phytotherapeutics, liposomes encapsulating immune boosting agent, and PEGylated peptide.

Ultra-High-Performance Liquid Chromatography(UHPLC)-High-resolution Mass Spectrometry (HRMS)

At BOC Sciences, a UHPLC-HRMS method was developed for the rapid identification of nonionic surfactants such as polysorbates. Identification is carried out based on their MS/MS data and further confirmed by NMR. A mathematical model was then developed to predict all possible components of the excipients.

High-Performance Anion-Exchange Chromatography (HPAEC)-Pulsed Amperometric Detection (PAD)

Our team of experts develops an analytical method that accurately identifies sugar-based excipients. HPAEC-PAD supported by gas chromatography-mass spectrometry (GC-MS) provides a method for the analysis of carbohydrate-based excipients. The analytical method is able to be used to distinguish some substitution patterns of monosaccharides from commonly used excipients .