Determination of Trace Tetracycline in Waste-water by Phase-separation Floatation with Ultraviolet Detection

A new analytical method was demonstrated for the determination of trace tetracycline (TC) in medicine by phase-separation floatation(PSF) coupled with an ultraviolet detector setting at 383 nm. TC can be transformed into binary complex(Mg-TC) in the conditions of magnesium(II) which can be separated by phase-separation floatation easily. The optimum phase-separation floatation was performed on phase-separation reagent using 3.5 mol·L^-1 sodium chloride, 0.01 mol·L^-1 sodium hydroxide as acidity regulator and n-propyl alcohol as solvent. The linear regression equation is A=1.912 × 10⁵ C+0.011, linear range is from 1.7×10^-7-1.02 × 10^-5 mol·L^-1, floating rate is 89.0%, enrichment multiple is 26.7. The recoveries of TC in urine were 96.1-98.2%.