This paper reports the development of a new method for quantification of the hydrolytic surface degradation kinetics of biodegradable poly(alpha-hydroxy acid)s using time-of-flight secondary ion mass spectrometry (TOF-SIMS). We report results from static SIMS spectra of a series of poly(alpha-hydroxy acid)s including poly(glycolic acid), poly(L-lactic acid), and random poly(D,L-lactic acid-co-glycolic acid) hydrolyzed in various buffer systems. The distribution of the most intense peak intensities of ions generated in high mass range of the spectrum reflects the intact degradation products (oligomeric hydrolysis products) of each biodegradable polymer. First, a detailed analysis of the oligomeric ions is given based on rearrangement of the intact hydrolysis products. The pattern of ions can distinguish both degradation-generated intact oligomers and their fragment ion peaks with a variety of combinations of each repeat unit. Then, the integration and summation of the area of all ion peaks with the same number of repeat units is proposed as a measurement that provides a more accurate MW average than the typically used method which counts only the most intense peak. The multiple ion summation method described in this paper would be practical in the improvement of quantitative TOF-SIMS studies as a better data reduction method, especially in the surface degradation kinetics of biodegradable polymers.

中文翻译：

---

可生物降解的聚（α-羟基酸）表面低聚降解产物的TOF-SIMS定量分析。

本文报道了一种使用飞行时间二次离子质谱（TOF-SIMS）量化可生物降解的聚（α-羟基酸）的水解表面降解动力学的新方法的开发。我们报告了一系列聚（α-羟基酸）的静态SIMS光谱结果，其中包括聚乙醇酸，聚L-乳酸和无规聚D，L-乳酸-共-乙醇酸在各种缓冲系统中水解。在质谱的高质量范围内生成的离子的最强峰强度的分布反映了每种可生物降解聚合物的完整降解产物（低聚水解产物）。首先，基于完整水解产物的重排给出了寡聚离子的详细分析。离子的模式可以通过每个重复单元的各种组合来区分降解生成的完整低聚物及其片段离子峰。然后，建议使用具有相同重复单元数的所有离子峰的面积求和和求和，以提供比通常只计算最强峰的方法更准确的MW平均值的测量。本文中描述的多离子求和方法作为一种更好的数据缩减方法，尤其是在可生物降解聚合物的表面降解动力学方面，将在改进定量TOF-SIMS研究方面是实用的。建议将具有相同重复单元数的所有离子峰的面积进行积分和求和，以提供比通常只计算最强峰的方法更准确的MW平均值的测量。本文描述的多离子求和方法作为一种更好的数据缩减方法，特别是在可生物降解聚合物的表面降解动力学方面，将在改进定量TOF-SIMS研究方面是实用的。建议将具有相同重复单元数的所有离子峰的面积进行积分和求和，以提供比通常只计算最强峰的方法更准确的MW平均值的测量。本文描述的多离子求和方法作为一种更好的数据缩减方法，特别是在可生物降解聚合物的表面降解动力学方面，将在改进定量TOF-SIMS研究方面是实用的。