An automatic potentiometric titration method is developed to determine the concentration of ammonium chloride in plating aid for hot dip galvanizing.The study also examines the impact of various factors,such as the dosage of compound masking agent A,the medium conditions for adding compound masking agent,and the initial pH of titration,on the titration jump.Furthermore,a comprehensive validation of the methodology is conducted.Experimental findings indicate that a solution containing 15 mL of composite masking agent A and 5 mL of 1∶1 formaldehyde solution are added into the plating aid that contains 10 g·L-1 of ammonium chloride at a pH of 5-6.The solution is then titrated using a 0.1 mol·L-1 sodium hydroxide solution and an automatic potentiometer.Methodological validation demonstrates that the linear regression equation is y=0.9349x-0.04325,with an r2 value of 1,indicating a strong linear relationship between sodium hydroxide consumption and ammonium chloride concentration in the range of 5 g·L-1 to 40 g·L-1.The method is repeated six times,and the recovery rate of spiked samples ranges from 100.1%to 100.8%,indicating a high accuracy.RSD value(n=7)is 0.28%for the consumption of 0.1 mol·L-1 sodium hydroxide by various personnel and instruments over seven trials.Similarly,RSD value(n=7)for the content of ammonium chloride is found to be 1.28%.Experimental findings accord with China's national standard requirement of RSD<5%,and statistical analysis reveal no significant difference in determination results(t=1.329,P>0.05).
NETL
NSTL
万方数据
