Balbinot Filho Clóvis A, Teixeira Renata F, Dias Jônatas L, Rebelatto Evertan A, Lanza Marcelo
Department of Chemical and Food Engineering, Federal University of Santa Catarina, UFSC, PO Box 476, 88040-900 Florianópolis, SC, Brazil.
ACS Omega. 2024 Jun 20;9(26):28776-28783. doi: 10.1021/acsomega.4c03172. eCollection 2024 Jul 2.
Vitamin C (l-ascorbic acid, ASC) and the amide form of vitamin B3 nicotinamide (NIC) can form cocrystals through hydrogen bonding. Currently, there is a lack of fast and reliable alternatives for precisely quantifying cocrystal components and their purity. Spectrophotometric analysis for quantifying such vitamin preparations is challenging due to overlapping absorbance bands in a narrow wavelength range in the ultraviolet (UV) region. Moreover, ASC undergoes progressive degradation if not diluted in a proper medium, requiring stability during quantitative analysis. This study adopted a fast, simple, and reliable two-component spectrophotometric assay for simultaneously determining ASC and NIC based on the first-order derivative spectrophotometry (FODS) method using sodium oxalate as a stabilizer for vitamin C. The FODS method showed linearity between 2 and 24 μg·mL and good precision. The standard addition method was employed to validate FODS, with high recovery percentages (96.5 to 102.4% for ASC and 95.3 to 101.9% for NIC). The FODS method was successfully applied to quantify ASC and NIC in bulk powder produced by the gas antisolvent method. The proposed method could estimate cocrystal purity through mass balance regarding the expected 1:1 stoichiometry, confirmed by PXRD and DSC. Cocrystal purity determined by the FODS method (58-100%) aligned well with results from LC-MS (62-100%), with an accuracy exceeding 97%. The FODS method is as sensitive and accurate as high-performance liquid chromatography for simultaneously determining vitamin concentrations deriving from cocrystals. However, it is less costly, more efficient, and a suitable alternative to classical solid-state methods for estimating cocrystal purity.
维生素C（l-抗坏血酸，ASC）和维生素B3烟酰胺（NIC）的酰胺形式可通过氢键形成共晶体。目前，缺乏快速可靠的方法来精确量化共晶体成分及其纯度。由于在紫外（UV）区域的窄波长范围内吸光度带重叠，用于量化此类维生素制剂的分光光度分析具有挑战性。此外，如果不在适当的介质中稀释，ASC会逐渐降解，这就要求在定量分析过程中保持稳定性。本研究采用了一种快速、简单且可靠的双组分分光光度法，基于一阶导数分光光度法（FODS），以草酸钠作为维生素C的稳定剂，同时测定ASC和NIC。FODS方法在2至24μg·mL之间呈线性，精密度良好。采用标准加入法验证FODS，回收率较高（ASC为96.5%至102.4%，NIC为95.3%至101.9%）。FODS方法成功应用于定量通过气体抗溶剂法生产的散装粉末中的ASC和NIC。所提出的方法可以通过关于预期1:1化学计量比的质量平衡来估计共晶体纯度，这通过粉末X射线衍射（PXRD）和差示扫描量热法（DSC）得到证实。通过FODS方法测定的共晶体纯度（58 - 100%）与液相色谱 - 质谱联用（LC - MS）结果（62 - 100%）吻合良好，准确度超过97%。FODS方法在同时测定共晶体中维生素浓度方面与高效液相色谱法一样灵敏和准确。然而，它成本更低、效率更高，是估计共晶体纯度的经典固态方法的合适替代方法。
