Microemulsion Medium-Spectrometric Determination of Zinc in Crude Oils With 5-Br-PADAP

The determination of zinc with 5-Br-PADAP was studied in the medium of O/W microemulsion SDS-n-C_4H_9OH-n-C_7H_(16)-H_2O and NH_3CL-NH_4·H_2O buffer solution (mass fraction of water is 80%). The complex compound of zinc maximum absorption wavelength is at 555 nm.The Beer's law is obeyed by zinc in the mass concentration range of 0 to 10 mg/L. The molar absorption coefficient is 1.24×10~5 L·mol~(-1)·cm~(-1). zinc in crude oil was determined while interfere ions were masked by triethanolamine and sulfourea solution as screening agent.The mean recovery rate of the synthetic sample is 100.15%. The RSD is 1.13%. The content of Zinc in Fuyu crude oil and Daqing vacuum residuum were determined. The relative standard deviation is 2.11% and 2.46% respectively. The mean recovery rate of standard added is 101.96% and 101.66% respectively. Comparing to the correspond micellar system, the sensitivity is enhanced 2.5 times in the medium of O/W microemulsion. The method has good accuracy and selectivity.