Abstract
A rapid method for the determination of micromoisture in surfactants by near-infrared spectroscopy was established.
Using carbontetrachloride-DMSO (3 : 1, vol/vol) as the solvent, water has strong absorption at 1.94 u in the near-infrared region. The linear relationship is obtained between the absorbance value at 1.94μ and water content. Further, various surfactants is dissolved readily by DSMO.
Based on these facts, in this method, surfactant sample (containing 520 mg of the water) was weighed into 50 ml volumemetric flask, and was dissolved with 12.5 ml of DMSO, and carbontetrachloride was added until marked line. The spectrum of the solution was measured from 1.7 to 2.1 μ in 10 cm quartz cell. And the absorbance value was obtained from peak-height of the band at 1.94μ by the baseline method. The moisture content was obtained from the absorbance value and the calibration curve.
The results show that the micromoisture of various surfactants can be determined rapidly and with accuracy (deviation 2.1%) by this method. The concentration of detection limit was 1 mg in 50 ml sample soln.
