Calibration of Glassware
Volumetric glassware’s are calibrated at 23° to 27°C temperature.
Pharmacopoeia assay and other tests involving volumetric measurements
require the use of accuracy-calibrated
glassware.
Clean the glassware for calibration to remove any grease, dust etc.
Ensure that glassware is completely dry.
Remove the glassware from the oven and keep it in desiccator, ensure
that the ambient temperature is 25°C ± 2°C.
Place the glassware to be calibrated on the balance and note the weight,
remove the glassware and transfer the distilled water at 25°C so that
the meniscus of liquid in the glassware on the mark level. Weigh the glassware
and note down the weight.
Take volumetric flask (e.g., for 10 to 1000 ml)
Volumetric Flask:
|
Nominal Capacity, (ml)
|
10
|
25
|
50
|
100
|
250
|
500
|
1000
|
|
Tolerance ± (ml)
|
|||||||
|
Class A
|
0.02
|
0.03
|
0.04
|
0.06
|
0.10
|
0.15
|
0.20
|
|
Class B
|
0.04
|
0.06
|
0.08
|
0.15
|
0.20
|
0.30
|
0.80
|
(e.g., for 10 ml volumetric flask)
Wt. taken of volumetric flask = W g
Wt. of volumetric flask + water (upto the mark level)
= W1 g
Wt. of water = W1 – W g
One Mark
Pipette (bulb pipette)
|
Normal capacity, (ml)
|
1
|
2
|
5
|
10
|
25
|
50
|
|
Tolerance ± (ml)
|
||||||
|
Class A
|
0.006
|
0.006
|
0.01
|
0.02
|
0.03
|
0.04
|
|
Class B
|
0.02
|
0.02
|
0.03
|
0.04
|
0.06
|
0.08
|
Wt. of water = W1 – W g
Graduated Pipette
|
Normal Capacity,(ml)
|
1
|
2
|
5
|
10
|
25
|
|
Sub Division (ml)
|
0.01
|
0.02
|
0.05
|
0.1
|
0.1
|
|
Tolerance ± (ml)
|
|||||
|
Class A
|
0.006
|
0.01
|
0.03
|
0.05
|
0.10
|
|
Class B
|
0.02
|
0.06
|
0.10
|
0.15
|
0.1
|
Wt. of volumetric flask + water (upto the mark level) = W1 g Wt. taken of volumetric flask = W g
Wt. of water = W1 – W g
Burette
Normal Capacity,(ml)
|
10
|
25
|
50
|
Sub Division (ml)
|
0.05
|
0.05
|
0.1
|
Tolerance ± (ml)
|
|||
Class A
|
0.01
|
0.03
|
0.05
|
Class B
|
0.02
|
0.06
|
0.10
|
Wt.
taken of volumetric flask = W g
Wt.
of volumetric flask + water (upto the mark level) = W1 g
Wt.
of water = W1 – W g/0.997
