甲酚红探针双波长负吸收分光光度法测定酒石酸美托洛尔

Determination of metoprolol tartrate by dual-wavelength negative absorption spectrophotometry with cresol red as probe

在弱碱性Tris-盐酸介质中,酒石酸美托洛尔与甲酚红反应生成具有2个负吸收峰的红色离子缔合物,最大负吸收波长位于556 nm,次大负吸收波长位于584 nm,表观摩尔吸光系数(κ)分别为4.22×10~4L/(mol·cm)(556 nm)和3.74×10~4L/(mol·cm)(584 nm),酒石酸美托洛尔的质量浓度在0.06~4.1 mg/L范围内服从比尔定律,检出限分别为0.045 mg/L(556 nm)和0.052 mg/L(584 nm)。当采用双波长叠加负吸收分光光度法测定时,其表观摩尔吸光系数(κ)可达7.96×10~4L/(mol·cm),检出限为0.024 mg/L。探讨了吸收光谱特征、适宜显色反应条件及共存物质的影响。该方法的加标回收率和相对标准偏差RSD(n=5)分别为98.60%~102.8%和1.9%~2.3%,该方法适于市售酒石酸美托洛尔药物中酒石酸美托洛尔的测定。

In a weak alkaline Tris-hydrochloric acid medium,metoprolol tartrate reacts with cresol red to form an red ionic association complex with two obvious negative absorption peaks. The maximum negative absorption wavelength locates at 556 nm and the second largest negative absorption wavelength locates at 584 nm. Their apparent molar absorptivity（ κ） are 4. 22×10~4 L/（ mol·cm）（ 556 nm） and 3. 74×10~4 L/（ mol·cm）（ 584 nm） respectively. Metoprolol tartrate obeys Beer＇s law in definite mass concentration range of 0. 06 to 4. 1 mg·L^（-1） and the detection limits are 0. 045 mg·L^（-1）（ 556 nm） and 0. 052 mg·L^（-1）（ 584 nm） respectively.When the dual-wavelength superposition negative absorption spectrophotometry is used to determine the concentrations of metoprolol tartrate,its apparent molar absorptivity（ κ） can achieve 7. 96×10~4 L/（ mol·cm） and the detection limit is 0. 024 mg·L^（-1）.The absorption spectral characteristics,suitable chromogenic reaction conditions and effects of the coexistence material are studied. The standard addition recovery and RSD（ n = 5） are in the ranges of 98. 60%-102. 8% and 1. 9%-2. 3% respectively when this method is applied to determine the content of metoprolol tartrate in drug.This method is suitable for the determination of metoprolol tartrate in commercially available metoprolol tartrate medicine.