Title: Calibration of Glassware’s

Title: Calibration of Glassware’s

1. Objective:

To lay down the Procedure for Calibration of Volumetric Glassware. 

    

2. Scope:

This procedure is applicable for Verification or Calibration of Volumetric Glassware used in Quality Control Department.

 

3. Responsibility:
   • Quality Control Department: To prepare and review the SOP. To follow the Procedure for Verification or Calibration of Volumetric Glassware as per this SOP.
   • Quality Assurance Department: To review and approve the SOP and Annexure.

 

4. Accountability:

Head Quality Control Department, Head Quality Assurance Department.

5. Procedure:

5.1	Procedure for Verification or Calibration of Glassware :
5.1.1	On receipt of volumetric glassware it should be calibrated before use.
5.1.2	It is not safe to assume that the volume delivered by or contained in any volumetric apparatus is exactly the amount indicated by the calibration mark.
5.1.3	Recalibration is usually performed by weighing the amount of water delivered by or contained in the volumetric apparatus.
5.1.4	The mass is then converted to the desired volume using the tabulated density of Water : Volume = mass / density
5.1.5	The volume occupied by a given mass of liquid varies with temperature. The volume of the device that holds the liquid with 25 °C with temperature has been chosen as the normal temperature for calibration of many volumetric glassware.
5.1.6	1.       Glass is a fortunate choice for volumetric ware as it has a relatively small coefficient of thermal expansion; a glass vessel which holds 1.00000 L at 15°C, holds 1.00025 L at 25°C.
5.1.7	2.       A correction for this expansion must frequently be applied during calibration procedures.
5.1.8	3.       If the correction is small enough it may be ignored.
5.1.9	Temperature °C Density (g/ml) Temperature °C Density (g/ml) 20 0.99823 24 0.99733 21 0.99802 25 0.99707 22 0.99780 26 0.99681 23 0.99757 27 0.9965162 Thermal expansion chart
5.2	Cleaning of glassware before calibration:
5.2.1	Cleaning of volumetric glassware is necessary before calibration, to remove any contaminants for accurate calibration.
5.2.2	4.       Two or three rinsing with tap water, a moderate amount of agitation and two or three rinsing with distilled water are generally sufficient and drying at 60±5°c for one to two hours.
5.2.3	Remove the glassware from the drier and cool them at room temperature.
5.3	Calibration of Glassware’s:
	A.              Calibration or Verification of volumetric flasks:
5.3.1	The Volumetric Flask is used to prepare Standard Solutions or dilution.
5.3.2	Most of these flasks   are calibrated To-Contain (TC) a given volume of liquid.
5.3.3	Weigh and note the weight of previously dried and cooled empty volumetric flask at ≈ 25°C.
5.3.4	Fill the weighted volumetric flask up to mark with boiled and cooled purified water at ≈ 25°C and record the weight.
5.3.5	If any droplets of solvent adhere to the neck, use a piece of tissue to blot these out.
5.3.6	Calculate the weight of the water occupied by volumetric flask and divide with density of water or theoretical as 0.99707 g/ml at 25°C.
5.3.7	Record the data in Glassware Verification /Calibration record as per Annexure No. 01.
	B.              Calibration or Verification of graduated and volumetric pipettes:
5.3.8	Drainage rates from  the  pipette  must  be carefully controlled so as to leave a uniform and reproducible film along the inner glass surface.
5.3.9	To fill the pipette, insert it vertically in the liquid, with the tip near the bottom of the container.
5.3.10	Apply suction to draw the liquid above the mark.
5.3.11	Quickly place a fore finger over the end of the stem.
5.3.12	Withdraw the pipette from the liquid and use a dry paper to wipe off the stem.
5.3.13	Now place the tip of the pipette against the container from which the liquid has been withdrawn and drain the excess liquid such that the meniscus is at the graduation mark.
5.3.14	Record the weight of a cleaned and dried beaker at ≈ 25°C.
5.3.15	Allow the liquid to flow out of the pipette freely into the weighed beaker.
5.3.16	When most of the liquid has drained from the pipette, touch the tip to the wall of the container until the flow stops and for an additional count of 10.
5.3.17	Re -weigh the beaker.
5.3.18	Calculate the weight of the water occupied by pipette and divide with density of water or theoretical as 0.99707 g/ml at 25°C.
5.3.19	Record the data in Glassware Verification/Calibration record as per Annexure No. 01.
	C.              Calibration or Verification of Burettes:
5.3.20	Fill the burette to above the zero mark and open the stopcock to fill the tip.
5.3.21	Remove air bubbles of the tip by tapping the tip while solution is draining.
5.3.22	Burette calibration is to be calibrated for 20%, 60% and 100% of the claimed volume.
5.3.23	The initial burette reading is taken 15-30 second, after the drainage of liquid has ceased.
5.3.24	The meniscus can be highlighted by holding a white piece of paper with a heavy black mark on it behind the burette.
5.3.25	Record the weight of cleaned and dried beaker at ≈ 25°C.
5.3.26	Fill the burette up to mark with boiled and cooled purified water at ≈ 25°C.
5.3.27	If burette capacity is 100  ml,then transfer 20 ml of volume of water to beaker and record the weight.
5.3.28	Repeat the same procedure after transfering 60 ml and 100 ml of water.
5.3.29	Same procedure is followed for burette of 25 ml and for 50 ml capacity .
5.3.30	Calculate the weight of the water occupied by burette and divide with density of water or theoretical as 0.99707g/ml at 25°C.
5.3.31	Record the data in Glass ware Verification/Calibration record as per Annexure.
5.3.32	For Tolerance limits of volumetric glassware refer below Annexure.
5.3.33	After calibration or verification test of the volumetric glassware it can be use for analysis and data with party COA for A grade glassware should be recorded for reference.
5.3.34	If any glassware does not passes the test of calibration, then repeat the same and reject if results are does not comply with acceptable criteria.

 

6. Definitions / Abbreviations:

• Definitions:
• Abbreviations:

 

Abbreviation	Expansion
SOP	Standard Operating Procedure
QC	Quality Control
QA	Quality Assurance
TC	To Contain
g	gram
L	Litre
%	percentage

 

Tolerance Limits of Volumetric Glassware

         

• Volumetric Flasks: IS 915:2012

 

Nominal Capacity in ml	5	10	25	50	100	250	500	1000
Tolerance ± ml for Class A AAAAAA	0.025	0.025	0.04	0.06	0.1	0.15	0.25	0.4
Tolerance ± ml for Class B	0.0504	0.05	0.08	0.12	0.2	0.3	0.5	0.80

 

2    Volumetric Pipettes: IS 1117:1975

 

Nominal Capacity in ml	1	2	5	10	20	25	50	1000
Tolerance ± ml for Class A	0.007	0.01	0.015	0.02	0.03	0.03	0.05	0.08
Tolerance ± ml for Class B	0.015	0.02	0.03	0.04	0.06	0.06	0.1	0.16

 

3    Graduated Pipettes: IS 4162:1985

Nominal Capacity in ml	1	2	5	10	25
Sub division ,ml	0.01	0.02	0.05	0.10	0.2
Tolerance ± ml for Class A	0.006	0.01	0.03	0.05	0.1
Tolerance ± ml for Class B	0.01	0.02	0.05	0.1	0.2

 

• Burettes: IS 1997:1967

Nominal Capacity in ml	10	25	50	100
Sub division ,ml	0.05	0.05	0.1	0.2
Tolerance ± ml for Class A	0.03	0.03	0.05	0.1
Tolerance ± ml for Class B	0.05	0.05	0.1	0.2

 

*Note – Ready to use SOP available in “DOWNLOAD” Section.