Gold T B, Buice R G, Lodder R A, Digenis G A
Division of Medicinal Chemistry and Pharmaceutics, College of Pharmacy, University of Kentucky, Lexington 40536-0082, USA.
Pharm Dev Technol. 1998 May;3(2):209-14. doi: 10.3109/10837459809028497.
The purpose of this research was to monitor the migration of formaldehyde from a polyethylene glycol (PEG) fill into the gelatin shell of a soft elastic gelatin capsule (SEGC) using near-infrared (NIR) spectrophotometry. SEGCs were filled with five solutions of aqueous formaldehyde in PEG (0, 0.05, 0.10, 0.20, and 0.40 v/v%), stored at ambient conditions for 48 hr, emptied, and scanned in NIR spectrophotometer. Principal component regression (PCR) was employed to analyze the spectra of the empty capsules. Good correlation was established (r2 = 0.988) when actual concentrations of formaldehyde in the PEG fill of the capsules were regressed against the principal component (PC) values from NIR spectra of the emptied and washed capsules. The loadings of the first PC describe a baseline shift in the spectra that arises from a change in water concentration. Lower PC loadings reveal the presence of signals at 1780 and 2200 nm that are not due to water absorbance, confirming the hypothesis that chemical bonds are formed during the formaldehyde-induced crosslinking of the gelatin in SEGCs. Gelatin crosslinking, initiated by formaldehyde migration from the PEG fill into the shell of an SEGC, was detected by NIR spectrophotometry. When NIR was coupled to principal component analysis, a linear relationship was found between the NIR spectra of empty SEGCs and the amount of crosslinking induced by concentrations of formaldehyde in the original fill material.
本研究的目的是使用近红外（NIR）分光光度法监测聚乙二醇（PEG）填充物中甲醛向软弹性明胶胶囊（SEGC）明胶壳的迁移情况。将SEGC填充五种PEG中甲醛水溶液（0、0.05、0.10、0.20和0.40 v/v%），在环境条件下储存48小时，排空后在NIR分光光度计中进行扫描。采用主成分回归（PCR）分析空胶囊的光谱。当将胶囊PEG填充物中甲醛的实际浓度与排空并清洗后的胶囊NIR光谱的主成分（PC）值进行回归分析时，建立了良好的相关性（r2 = 0.988）。第一主成分的载荷描述了由于水浓度变化而引起的光谱基线偏移。较低的主成分载荷揭示了在1780和2200 nm处存在并非由水吸收引起的信号，证实了在SEGC中甲醛诱导明胶交联过程中形成化学键的假设。通过NIR分光光度法检测到甲醛从PEG填充物迁移到SEGC壳中引发的明胶交联。当将NIR与主成分分析相结合时，发现空SEGC的NIR光谱与原始填充材料中甲醛浓度诱导的交联量之间存在线性关系。
