A novel visible spectrophotometric method for the determination of methanol using sodium nitroprusside as spectroscopic probe

Abstract

A novel, rapid and reliable method has been established for the determination of methanol using sodium nitroprusside as a spectroscopic probe. Thismethod indicates that the sodium nitroprusside can react with the methanol to form a colored product in the basic solution. The absorbance of the product is measured at the maximal absorption wavelength of 481 nm, and the amount of methanol can be calculated based on this absorbance. Agood linear relationship of the concentration ofmethanol versus absorbance is observed with a linear range of 0.02-6.0 mg mL-1. The linear regression equation is A = 0.02484 + 0.29457C (mgmL-1), with a correlation coefficient of 0. 9991. The detection limit (3σ/k) is 0.012 mg mL-1, while its R.S.D. is 1.5% and the recovery rate is 97.5-102.5%. The parameters with regard to determination are optimized, and the reaction mechanism is discussed. This method has been successfully applied to determine methanol in variety of samples. Analytical results obtained by this new method were very gratifying.