ABSTRACT
Objective@#To establish a continuous flow injection analysis with potassium permanganate for determination of oxygen consumption in water.@*Methods@#The water samples and acid potassium permanganate working solutions were mixed using the continuous flow bubble spacing, and subjected to online heating reaction at 97 ℃. The peak height of the electrical signal of potassium permanganate was measured at the maximum absorption wavelength of 520 nm, and the standard substance, sulfuric acid concentration and potassium permanganate concentration were optimized according to the peak height of the electrical signal. The standard curve was plotted to measure the limit of detection, the limit of quantification, and spiked recovery rate of the method. The CODMn concentration was determined in 40 drinking water samples using acid potassium permanganate titration and continuous flow injection analysis using potassium permanganate, and the determination results of the two methods were compared with paired t-test.@*Results@#Glucose was selected as the standard substance, and the mixture of 17.5% sulfuric acid and 3.2 mmol/L potassium permanganate was selected as the working solution. CODMn had a good linear relationship at concentrations of 0 to 6.00 mg/L, with a correlation coefficient of 0.999 and higher, a detection limit of 0.013 mg/L and a quantitation limit of 0.043 mg/L, respectively. The spiked recovery rates were 90.00% to 105.00% in 40 drinking water samples, with relative standard deviations of 0.12% to 1.36%. The determination results of two permanganate index standard substances were all within the range of standard values. The relative errors of CODMn concentration were 1.55% to 9.26% between the continuous flow injection analysis using potassium permanganate and acid potassium permanganate titration, and there was no significant difference (t=2.023, P=0.185). @*Conclusion@#The established continuous flow injection analysis with potassium permanganate is feasible for batch determination of oxygen consumption in water.
ABSTRACT
Objective To develop a stable and quick method to determine the urea in swimming pool water.Methods On the conditions of strong acid and calefaction,urea can react on antipyrine and diacetyl monoxime and become yellow which can be determined by colorimetric analysis in 450 nm with the ALLIANCE FUTURA continuous flow injection auto analysis system.Results Determined by this method,the linear range was 0.5-4.0 mg/L,the regression equation was y=0.077 5x+0.021 9,the correlative coefficient r=0.999,the detection limit was 0.07 mg/L.With residual chlorine of 0.3 and 3.0 mg/L,the recovery rates were 98.8%-104.0% and did not disturb the determination.The results determined by the present method were the same as those by the method in GB/T 18204.29-2000(Wilcoxon Signed Ranks Test:Z=0.051,P=0.959).Conclusion Determination of the urea in swimming pool water with continuous flow injection auto analysis,the sensitivity,accuracy and limit of determination can meet to the requirement,moreover,the analysis speed is faster,less reagent will be needed,the present method can be generalized in the laboratory that has the conditions.
ABSTRACT
Objective To establish a simple,accurate and sensitive method for determination of cyanide in drinking water. Methods By means of using flow injection analysis instrument, the cyanide in drinking water was determined on-line. Results The data obtained by this assay accorded with Beer's Law, the range was 2.0-50.0 ?g/L, r≥0.999, the detection limit, relative standard deviation and recovery rate were 0.23 ?g/L, 2.5%-3.8% and 94.9%-98.7% respectively. The sampling frequency was 20 samples per hour. Conclusion The method for determination of cyanide in drinking water employed in the present paper is simple, accurate, sensitive and suitable for the analysis of large number of water samples.