Specific Gravity Determination Using a Pycnometer

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1.0 Purpose 
 
 The purpose of this procedure is to describe a method for specific gravity determination of
 
 finished products and raw materials using a pycnometer. 
 
 2.0 Scope 
 
 This procedure follows USP <841> Specific Gravity Method I guidelines and is designed
 specifically for measuring free flowing liquids. 
 
 3.0 Responsibility 
 
 3.1 It is the responsibility of QC and Analytical Chemists to follow this procedure.
 
 3.2 It is the responsibility of QC Laboratory Management to implement this procedure and
 
 to ensure that the procedure is being followed. 
 
 3.3 ‘It is the responsibility of QC Laboratory Management and/or Analytical Development
 
 to keep this procedure aligned with current practices. 
 
 4.0 Definitions 
 
 4.1 STD — Standard 
 
 4.2. H20- Millipore Water,18.2Q 
 
 4.3, QC — Quality Control 
 
 4.4 CofA — Certificate of Analysis 
 
 

[SOP 

 Standard Operating Procedure SOP No Rev 
 Page 2 of 4 
 D-737 
 Specific Gravity Determination using a Pycnometer 
 5.0 References 
 
 5.1 USP <841> Specific Gravity, method I 
 
 5.2 D-737-F1, Form, Specific Gravity Test Ticket 
 
 6.0 Reagents and Equipment 
 
 6.1 Reagents 
 
 6.1.1 H20- 18.2Q Millipore Water 
 
 6.2 Equipment 
 
 6.2.1 Analytical Scale 
 
 6.2.2 25°C +/- 1°C Incubator 
 
 6.2.3. ImL pipette 
 
 6.2.4 200uL pipette 
 
 6.2.5 10mL pipette 
 
 6.2.6 Pycnometer 
 
 6.2.7 Beaker 
 
 7.0 Procedure 
 
 7.1 Preparation 
 
 7.1.1 Be sure to wear gloves during the course of the experiment as oils and dust on
 fingertips could influence the weight of the pycnometer. 
 
 7.1.2 Select a scrupulously clean, dry pycnometer that has been previously calibrated
 
 by determining its weight. 
 
 

[SOP 

 Standard Operating Procedure SOP No Rev sis on 
 Specific Gravity Determination using a Pycnometer D-737 5 8 
 
 7.1.3. Boil an appropriate amount of Millipore water for the testing.
 
 Tad Standard Preparation and Measurement 
 
 7.2.1 Fill the pycnometer until the liquid level is just below the rim using recently
 boiled water cooled to room temperature (below 25°C). Avoid trapping air
 
 bubbles in the water. 
 
 7.2.2 Place the perforated lid on top of the cup and seal it with a careful twisting
 
 motion. An excess of liquid should ooze (not squirt) out of the small hole on
 
 top of the snugly fitting lid. Wipe off this excess water using a soft cloth or
 tissue paper. 
 
 7.2.3 Place filled pycnometer in a 25°C incubator for 15 minutes to equilibrate
 
 temperature 
 
 7.2.4 If it a temperature other than 25°C is specified the water and sample should be
 heated to that temperature. 
 
 7.2.5 Weigh the properly filled cup to the nearest 0.1 milligram and document the
 
 weight. 
 
 7.3 Sample Preparation and Measurement 
 
 7.3.1 Fill the pycnometer until the sample liquid level is just below the rim using
 
 sample liquid that is below 25°C. Avoid trapping air bubbles in the sample
 
 liquid. 
 
 7.3.2 Place the perforated lid on top of the cup and seal it with a careful twisting
 
 motion. An excess of liquid should ooze (not squirt) out of the small hole on
 top of the snuggly fitting lid. Wipe off this excess liquid using a soft cloth or
 
 tissue paper or wash off if necessary by holding pycnometer so that rinse solvent
 
 or water does not enter small hole in lid. Dry using a cloth or tissue.
 
 

[SOP 

 Standard Operating Procedure SOP No Rev 
 Page 4 of 4 
 D-737 
 Specific Gravity Determination using a Pycnometer 
 7.3.3 Place filled pycnometer in a 25°C incubator for 15 minutes to equilibrate
 
 temperature. 
 
 7.3.4 Weigh the properly filled cup to the nearest 0.1 milligram and document the
 
 weight. 
 
 7.4 Calculations 
 
 7.4.1 Use the calibration weight of the pycnometer that has been verified and subtract
 from the total weight of the standard and the sample. 
 
 7.4.1.1 Specific Gravity = [(weight of pyc + sample) — weight of pyc]
 
 [(weight of pyc + H2O) — weight of pyc] 
 
 7.4.2 Determine a specific gravity of the liquid by calculating the quotient obtained by
 
 dividing the weight of the sample liquid contained in the pycnometer by the
 
 weight of the water contained in it, both determined at 25°C unless otherwise
 directed. Report to three decimal places. 
 
 7.5 Requirements 
 
 7.5.1 Utilize form D-737-F1 Specific Gravity Test Ticket to report specific gravity
 
 findings. 
 
 7.5.2 Requirements for specific gravity are met if the result is within the specified
 
 range given on the CofA or in the product profile. 
 
 8.0 Revision History 

| Rev | Date | Description of Changes | CCR # | By |
|-----|----------|------------------------|-------|----|
| 3 | 01/14/19 | Scheduled review: updated SOP. 09/07/22 Scheduled review: updated SOP logo and format. CC-22-0368 K. Burris ? PE OOS U‘podtta tDe-d7 t3o7 -aFd d1 rtheafte rceannc ea ctcoe npte wu pf otor mt hDr-e7e3 t7e-stFs1 p.e Crr peaagtee.d new COGN2 7:a eNsene lsOn | 19-0038 | J. Maignan |

 

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