1.0 Purpose: This SOP describes a procedure for the measurement of capacity of volumetric flask.
2.0 Scope: This SOP is applicable to all volumetric flasks of different nominal capacity.
3.0 Responsibility: It is the responsibility of Quality Assurance Manager to ensure that the procedure is followed.
4.0 Materials and Equipment Used:
4.01A weighing balance that is calibrated with traceable weights and regularly maintained.
4.02 A calibrated thermometer.
4.03 A weighing vessel.
4.04 Distilled water.
4.05 Acetone.
4.06 4% Acetic acid solution
4.07 Worksheets or forms to record the raw data.
5.0 Procedure: The determination of capacity of volumetric flask is based on weighing water and calculating mass and volume based on the density at the appropriate temperature.
5.01 Clean the volumetric flask with soap solution and water to remove any adhering dirt or grease. Rinse the volumetric flask with acetic acid solution and then wash with water till free from all acid.
5.02 Dry the volumetric flask by rinsing with acetone.
5.03 Weigh a cleaned and dried volumetric flask (W1).
5.04 Fill the volumetric flask with distilled water at ambient temperature to a few ml below the graduation line.
5.05 Then hold the volumetric flask in a vertical position, and by adding more water, set the meniscus to the graduation line so that the plane of the top edge of the graduation line is horizontally tangential to the lowest point of the meniscus, the line of sight being in the same plane.
5.06 Again weigh the volumetric flask containing distilled water (W2).
5.07 Note the temperature of water and calculate the volume of water in the volumetric flask at the reference temperature of 270C.
6.0 Calculation: Calculate the volume of water filled in volumetric flask by using the following formula –
V= W2 – W1 / D
Where:
V = Volume of the volumetric flask, Cm3 (ml )
W1 = Weight of empty volumetric flask.
W2 = Weight of empty volumetric flask & distilled water.
D = Density of water at 270C (i.e. 0.9965 g /cc)
7.0 Reporting: Record all the observations in the worksheets or forms. Calculate the correct volume of water contained in volumetric flask and, the amount by which this differs from the indicated volume, is the volumetric error.