曙红亚甲基蓝光度法测定盐酸利多卡因

Spectrophotometric Method for Determining Lidocaine Hydrochloride with Eosin Methylene Blue

在pH5.74的HOAc-NaOAc的缓冲介质中,盐酸利多卡因（LDKI）与曙红亚甲基蓝（EMB）染料反应,形成离子缔合物,溶液颜色发生明显改变,最大吸收波长在508 nm处,在此波长处,盐酸利多卡因的浓度与溶液的增色程度呈良好线性关系,从而建立测定盐酸利多卡因的光度法.在最大吸收波长处,盐酸利多卡因的浓度在0-2.19×10^-5mol/L范围内遵守比尔定律,表观摩尔吸光系数为1.47×10^4L/（mol.cm）,检出限为5.92×10^-7mol/L.方法具有较高的灵敏度和良好的选择性,用于盐酸利多卡因注射液和胶浆剂中盐酸利多卡因的测定,结果满意.

In pH5.74 HOAc-NaOAc buffer medium, lidocaine hydrochloride（LDKI） reacts with eosin methylene blue （EMB） to form an ion-association complex, the colors of solutions change obviously, the absorption wavelength at 508 nm, and there exists a maximum absorption wavelength at 508 nm, a sensitive spectrophotometric method is developed for determining lidocaine hydrochloride. The concentration of lidocaine hydrochloride in the range of 0 - 2.19 × 10^-5 mol/L obeys Beer＇ law at the maximum absorption wavelength 508 nm, the apparent molar absorptivity ε508 is 1.47 × 10^4 L/ （mol·cm）, the detection limit is 5.92 × 10^-7 mol/L. The method has high sensitivity and fairly good selectivity. The method is applied to the determination of lidocaine hydrochloride in Injection and Mucilage, with satisfactory results.