分光光度法测定氨基甲酸甲酯和尿素混合物

Spectrophotometric determination of methyl carbamate and urea in their mixture

利用氨基甲酸甲酯和尿素在乙醚中的溶解度不同,首先将其混合物进行分离,二者在酸性溶液中与对二甲胺基苯甲醛进行Ehrlich反应,形成柠檬黄色衍生物,分别在416nm和440nm波长下测定它们的吸光度,在0～4.6mg mL和0～0.6mg mL范围内吸光度和质量浓度有良好的线性关系,线性回归方程分别为:AMC=0.3987ρ+0.0224,AUrea=2.505ρ-0.0228,表观摩尔吸光系数分别为:εMC=29.9L·mol-1·cm-1,εUrea=150.3L·mol-1·cm-1。该法测定准确度高,精密度好,所涉及到的分离过程简单。

The mixture of methyl carbamate and urea was first separated according to their different solubility in ether. The Ehrlich reaction occurred when either of them reacted with p-(dimethylamino) benzaldehyde in acidic solution and formed a lemon-yellow derivative, respectively. The amounts of them were determined by the absorbance at 416 nm and 440 nm, respectively. The absorbance of them had good linear relation ship with their concentration in the region of 0～4.6 (mg/mL) and 0～0.6 mg/mL, respectively. The linear regression equations were A_(MC)=0.3987 ρ +0.0224 and A_(Urea)=2.505 ρ -0.0228, respectively. The apparent molar absorption coefficients were ε_(MC)=29.9 L·mol^(-1)·cm^(-1) and ε _(Urea)=150.3 L·mol^(-1)·cm^(-1), respectively.