Determination of Chloroform in Extraction Raffinate by Distillation-Spectrophotometric Method
When spectrophotometric method was applied to determine the concentration of chloroform of raffinate left by extraction of N,N-dimethylformamide(DMF) from an leather manufacturing industrial waste water with chloroform as an extractant,the DMF in wastewater seriously interferes in the Fujiwara coloured reaction.This interference can be obviously eliminated by distillation pretreatment of sample before spectrophotometry detection.So,the distillation-spectrophotometric method was utilized for the determination of chloroform concentration in extraction raffinate,and was proved to be very efficient,and the effects of DMF concentration of the samples and of the distils,the percent vaporization of the samples were investigated,and a distillation-spectrophotometric analysis procedure or method were developed.The experimental results showed that a linear calibration plot(R=0.9983) for the distillation-spectrophotometric method was obtained within a chloroform concentration range of 0-0.75 g/L,and this method is an accurate one for determination of chloroform concentration in DMF containing wastewater or extraction raffinate with relative errors of 2.1% and 1.2% for initial chloroform concentration 5 g/L and 0.16 g/L respectively by comparison with static head-space gas chromatography and relative standard deviation of 6.6% in repeated determination chloroform concentration of 0.575 g/L by 7 times.The results of determination of chloroform concentration in wastewater containing [DMF]15 g/L were satisfactory.