Drug Discovery, Pharmaceuticals & Cannabis Testing
Quality control and stability monitoring of Vitamin C-containing products using a multiparameter measurement system
Tamas Kiss, Stefan Tanda, Anton Paar Gmbh, Graz/Austria.
Quality control and data integrity are crucial throughout the production process in the pharmaceutical and cosmetic industries. Multiparameter measurement systems, and integration with Anton Paar’s lab execution system, AP Connect, offer a robust solution for monitoring concentration changes due to production variations or material degradation.
Vitamin C, scientifi cally known as L-ascorbic acid, is widely utilised in the pharmaceutical and cosmetic industries due to its antioxidant, immune-boosting, and skin-rejuvenating properties. In pharmaceuticals, vitamin C is a key component in nutritional supplements, intravenous therapies, and dermatological treatments, aiding in immune support, wound healing, and collagen synthesis.
In cosmetics, it is a key active ingredient due to its multifaceted benefi ts for skin health. It neutralises free radicals, which would otherwise damage cells and plays a crucial role in the synthesis of collagen, a protein that is vital for the maintenance of skin elasticity and fi rmness. Research shows that vitamin C serums can signifi cantly reduce the appearance of wrinkles, improve skin texture, and enhance the skin’s natural healing process. These serums also have the ability to brighten the skin, making them effective in treating hyperpigmentation and age spots [1, 2]. Consequently, vitamin C is widely incorporated into various skin care products like serums, creams, and masks, formulations that deliver active ingredients deeply into the skin [3].
However, its high susceptibility to oxidation and degradation presents challenges in formulation stability and product effi cacy [4]. Ensuring rigorous quality control and stability monitoring is essential to maintaining potency and effectiveness throughout production and shelf life.
This article explores the importance of stability assessment and advanced quality control methods for vitamin C-containing products, highlighting the capabilities of Anton Paar’s multiparameter measurement systems (Figure 1), particularly when dealing with unstable active ingredients. When combined with AP Connect, Anton Paar’s lab execution system, data management is streamlined, ensuring precise and reliable analysis as well as secure, traceable, and effi cient handling of measurement data across the pharmaceutical and cosmetic industries.
• A freshly prepared, 12 % m/V L-ascorbic acid in a phosphate buffer solution (PBS; pH=6.2).
• A commercially available L-ascorbic acid-containing serum and its dilution series with bi-distilled water.
• L-ascorbic acid in both buffer and serum at 40 °C under ambient humidity conditions and a measurement period of 10 days in an impermeable container to carry out an accelerated stability study in accordance with ICH Q1 A (R2) guideline [5].
For these samples, the measurement system (Figure 1) with up to seven combinable modules was equipped with a fi ve-digit density meter (DMA), a multi-sample changer (Xsample 530) with a 35 mL x 20 mL magazine and a sample recovery unit (SRU), a polarimeter (MCP), a refractometer (Abbemat), and a colorimeter (Lovibond PFXi-Series). Optional modules for high-precision viscosity or turbidity measurements are also available.
This system was fi lled automatically directly from the sample vial. A completed fi lling triggered the measurement start in consecutive modules by determining, in parallel, density, optical rotation (OR), refractive index (RI), and multiple colour-related quantities. The SRU accessory was used to retrieve the sample, an important feature for valuable samples or when additional measurements of the same sample are required. After each sample, thorough cleaning of the hoses and modules was performed to prevent sample carryover and cross-contamination. A comprehensive overview of the device parameters and measurement settings is available in the corresponding application report [6].
To ensure fully automated data handling, the measurement system was connected to AP Connect, which serves as a centralised platform for collecting, processing, and managing all measurement data.
Measurement of the vitamin C degradation profi le in PBS
The degradation of vitamin C dissolved in PBS was analysed in a time series of 10 days within an accelerated stability study. To monitor the degradation, density, refractive index, optical rotation, and colour-related quantities were measured. The measurements showed that density and refractive index were not robust enough to monitor the degradation process, whereas signifi cant changes were observed in optical rotation and colour-related quantities. The optical rotation decreased at an accelerating rate indicating a decreasing concentration of L-ascorbic acid (Figure 2).
Figure 1: A multiparameter measurement system with a density meter, multi-sample changer, polarimeter, refractometer, and colorimeter.
Design and operation of a confi gurable multiparameter measurement system
This section highlights the advantages of the modular, confi gurable multiparameter measurement system, designed for seamless adaption to various applications. In the described study the following samples were investigated:
Figure 2: Mean value ± standard deviation of the optical rotation over time as a result of L-ascorbic acid degradation in PBS (n=3).
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