Laboratory for Pharmaceutical Analysis, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, O&N 2, PO Box 923, Herestraat 49, B-3000 Leuven, Belgium.
J Pharm Biomed Anal. 2012 Feb 23;60:51-8. doi: 10.1016/j.jpba.2011.10.024. Epub 2011 Oct 25.
Capsaicinoids, salicylic acid, methyl and ethyl salicylate, glycol monosalicylate, camphor and l-menthol are widely used in topical formulations to relieve local pain. For each separate compound or simple mixtures, quantitative analysis methods are reported. However, for a mixture containing all above mentioned active compounds, no assay methods were found. Due to the differing physicochemical characteristics, two methods were developed and optimized simultaneously. The non-volatile capsaicinoids, salicylic acid and glycol monosalicylate were analyzed with liquid chromatography following liquid-liquid extraction, whereas the volatile compounds were analyzed with static headspace-gas chromatography. For the latter method, liquid paraffin was selected as compatible dilution solvent. The optimized methods were validated in terms of specificity, linearity, accuracy and precision in a range of 80% to 120% of the expected concentrations. For both methods, peaks were well separated without interference of other compounds. Linear relationships were demonstrated with R² values higher than 0.996 for all compounds. Accuracy was assessed by performing replicate recovery experiments with spiked blank samples. Mean recovery values were all between 98% and 102%. Precision was checked at three levels: system repeatability, method precision and intermediate precision. Both methods were found to be acceptably precise at all three levels. Finally, the method was successfully applied to the analysis of some real samples (cutaneous sticks).
辣椒素类、水杨酸、甲基水杨酸酯、乙基水杨酸酯、水杨酸甲酯、樟脑和薄荷醇广泛用于局部止痛的外用制剂中。对于每种单独的化合物或简单的混合物，都有报道其定量分析方法。然而，对于包含上述所有活性化合物的混合物，没有发现测定方法。由于具有不同的物理化学特性，同时开发并优化了两种方法。采用液液萃取后，用液相色谱法分析非挥发性辣椒素类、水杨酸和水杨酸甲酯，而采用静态顶空-气相色谱法分析挥发性化合物。对于后一种方法，选择液体石蜡作为相容的稀释溶剂。在 80%至 120%预期浓度范围内，对两种方法进行了专属性、线性、准确性和精密度验证。对于这两种方法，在没有其他化合物干扰的情况下，峰都得到了很好的分离。所有化合物的线性关系均表现出 R² 值高于 0.996。通过对加标空白样品进行重复回收实验来评估准确性。平均回收率均在 98%至 102%之间。在三个水平上检查了精密度：系统重复性、方法精密度和中间精密度。在所有三个水平上，这两种方法都被证明具有可接受的精密度。最后，该方法成功应用于一些实际样品（皮肤棒）的分析。
