Besides the racemate, the S-enantiomer of ibuprofen (Ibu) is used for the treatment of inflammation and pain. Since the configurational stability of S-Ibu in solid state is of interest, it was studied by means of ball milling experiments. For the evaluation of the enantiomeric composition, a chiral CE method was developed and validated according to the ICH guideline Q2(R1). The addition of Mg²⁺, Ca²⁺, or Zn²⁺ ions to the background electrolyte (BGE) was found to improve Ibu enantioresolution. Chiral separation of Ibu enantiomers was achieved on a 60.2 cm (50.0 cm effective length) x 75 μm fused-silica capillary using a background electrolyte (BGE) composed of 50 mM sodium acetate, 10 mM magnesium acetate tetrahydrate, and 35 mM heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD) as chiral selector. The quantification of R-Ibu in the mixture was performed using the normalization procedure. Linearity was evaluated in the range of 0.68–5.49% R-Ibu (R² = 0.999), recovery was found to range between 97 and 103%, the RSD of intra- and interday precision below 2.5%, and the limit of quantification for R- in S-Ibu was calculated to be 0.21% (extrapolated) and 0.15% (dilution of racemic ibuprofen), respectively. Isomerization of S-Ibu was observed under basic conditions by applying long milling times and high milling frequencies.

中文翻译：

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使用手性毛细管电泳研究右布洛芬在球磨机中的异构化

除消旋体外，布洛芬 (Ibu) 的S-对映异构体还用于治疗炎症和疼痛。由于S -Ibu 在固态下的构型稳定性令人感兴趣，因此通过球磨实验对其进行了研究。为了评估对映体组合物，根据 ICH 指南 Q2(R1) 开发并验证了手性 CE 方法。添加Mg ²⁺、Ca ²⁺或Zn ²⁺发现背景电解质 (BGE) 的离子可提高 Ibu 对映体分离度。使用由 50 mM 醋酸钠、10 mM 四水醋酸镁和 35 mM heptakis-( 2,3,6-三-O-甲基）-β-环糊精（TM-β-CD）作为手性选择剂。使用归一化程序对混合物中的R -Ibu 进行量化。在 0.68–5.49% R -Ibu (R ² = 0.999) 范围内评估了线性，发现回收率在 97% 和 103% 之间，日内和日间精度的 RSD 低于 2.5%，定量限为R - 在S-Ibu 分别计算为 0.21%（外推）和 0.15%（外消旋布洛芬稀释）。通过应用长研磨时间和高研磨频率在碱性条件下观察到S -Ibu 的异构化。