Application of Capillary Microburette to Drop-Counting Microtitrimetry and Evaluation of Its Uncertainty in Measurements

Polyethylene among glass and stainless steel was chosen as suitable material for fabrication of the capillary burette.The feasibility was tested by its application to the drop-counting microtitration of total acidity of vinegar,iodate in table salt,total hardness of water and dissolved oxygen in water.Uncertainty in measurements of the method of determination of total acidity of vinegar was evaluated As shown by the data of experiments,the volume of each droplet of titrant from the microburette was from 0.01 to 0.02 mL.When the total amount of titrant used in a titration was in range of 70-110 drops (ca.1 mL),values of RSD′s (n=6) obtained were in the range of 0.6%-1.8% for the above mentioned determinations,and values of recovery were in the range of 99.4%-101.4%.The expanded relative uncertainty evaluated was 1.0%.It was also shown that the drop-counting microtitrimetry was equivalent with the conventional macrotitrimetry both in accuracy and precision,while the microtitrimetry using the capillary microburette showed its special feutures of portableness,more economic,more rapid and convenient in operations.