Pospísilová M, Polásek M, Jokl V
Department of Analytical Chemistry, Faculty of Pharmacy, Charles University, Heyrovského, Czech Republic.
J Pharm Biomed Anal. 1998 Dec;18(4-5):777-83. doi: 10.1016/s0731-7085(98)00270-2.
Cationic capillary isotachophoresis (ITP) with conductometric detection has been used for separating and determining milligram amounts of tramadol [2-dimethylaminomethyl-1-(3-methoxyphenyl)-cyclohexanol hydrochloride] (I) in seven commercial mass-produced pharmaceutical preparations. The optimised ITP electrolyte system consisted of 5 mM potassium picolinate + 5 mM picolinic acid (pH 5.25) as the leading electrolyte and 10 mM formic acid as the terminating electrolyte. The driving and detection currents were 50 microA (for 320 s) and 10 microA, respectively (a single analysis took 12-15 min). Under such conditions the effective mobility of I was determined as 24.26 x 10(-9) m2 V(-1) s(-1) (with tetraethylammonium ion as standard); thermodynamic pKa value of I was 9.44 +/- 0.03 (n = 8) as determined by UV spectrophotometry at 25 degrees C and I = 0.01 (NaCl). The calibration graph relating the ITP zone length to the concentration of I was rectilinear (r = 0.99997) in the range 15-180 mg l(-1) of I. The relative standard deviation (RSD) was 0.21% (n = 6) when determining 60 mg l(-1) of I in pure test solution. Sample pre-treatment of the dosage forms involved dilution or extraction of I with water (for suppositories the extraction was carried out in an ultrasonic bath at 40 degrees C for 10 min). The method was suitable for determining 50 or 100 mg ml(-1) of I in injections and drops, 50 mg of I in capsules, and 100 mg of I in suppositories with RSD values 0.4 to 1% (n = 6). According to the validation procedure based on the standard addition technique the recoveries were 97.2-100.1% of I.
采用具有电导检测的阳离子毛细管等速电泳（ITP）法，对七种市售量产药物制剂中的毫克量曲马多[2 - 二甲基氨基甲基 - 1 -（3 - 甲氧基苯基） - 环己醇盐酸盐]（I）进行了分离和测定。优化后的ITP电解质系统由5 mM吡啶甲酸钾 + 5 mM吡啶甲酸（pH 5.25）作为前导电解质，10 mM甲酸作为终止电解质组成。驱动电流和检测电流分别为50 μA（持续320 s）和10 μA（单次分析耗时12 - 15分钟）。在此条件下，I的有效迁移率被测定为24.26×10⁻⁹ m² V⁻¹ s⁻¹（以四乙铵离子为标准）；通过25℃、I = 0.01（NaCl）条件下的紫外分光光度法测定，I的热力学pKa值为9.44±0.03（n = 8）。在I浓度为15 - 180 mg L⁻¹范围内，ITP区带长度与I浓度的校准曲线呈线性（r = 0.99997）。在纯测试溶液中测定60 mg L⁻¹的I时，相对标准偏差（RSD）为0.21%（n = 6）。剂型的样品预处理包括用水稀释或萃取I（对于栓剂，萃取在40℃超声浴中进行10分钟）。该方法适用于测定注射剂和滴剂中50或100 mg mL⁻¹的I、胶囊中50 mg的I以及栓剂中100 mg的I，RSD值为0.4%至1%（n = 6）。根据基于标准加入技术的验证程序，I的回收率为97.2% - 100.1%。
