NMR定量测定片剂中的对乙酰氨基酚

以基准试剂邻苯二甲酸氢钾为内标,采用1H NMR法建立了对乙酰氨基酚片剂中对乙酰氨基酚含量的测定方法。考察了延迟时间、脉冲宽度和采样次数对测定结果的影响。选定核磁共振参数延迟时间1 s、脉冲宽度3μs、采样次数16次。结果显示,测定内标与标样的NMR峰面积比均小于0.4%,方法具有很好的重复性。将内标与标样的NMR峰面积比对其质量比绘制标准曲线,相关系数为1.000 0,内标的质量浓度为6 g/L时,对乙酰氨基酚的线性范围为2～10 g/L。用标准曲线法和绝对定量模式(内标法)测定了3种不同厂家的片剂中对乙酰氨基酚的含量。结果表明此方法与紫外分光光度法的测定结果一致,方法简单易行、结果准确。

Determination of Paracetamol in Tablet by NMR

A proton-nuclear magnetic resonance(1H NMR) approach was presented for the determination of paracetamol in its tablet using potassium acid phthalate as the internal standard.Effects of some experiment parameters were investigated.The optimal conditions were selected as follows: relaxation delay time(D1):1 s,pulse width(P1):3 μs and transient number(NS):16.The result indicated that,under the optimal conditions,the good repeatability for the method was obtained as the peak area ratios of inner standard potassium acid phthalate to sample paracetamol were all less than 0.4%.A good linear relationship between peak area ratio and weight ratio of inner standard potassium acid phthalate(δ7.44) to sample paracetamol(δ6.76)was obtained in the paracetamol concentration range of 2-10 g/L(the concentration of internal standard was about 6 g/L),with correlative coefficient of 1.000 0.Three batches of real paracetamol tablets from different manufactures were determined by the method with standard curve and inner standard model,and the ultraviolet spectrophotometry method used in pharmacopoeia.The results indicated that two methods had no difference.