Osmolality is a great tool in biopharmaceutical development. However the rules of using the equipment differ in the EU from the US. Key differences:

• The EU requires a zero point calibration for osmolality.
• The EU requires calibration using at least 2 reference solutions.
• The EU recommends to rinse the sample container with the solution to be tested.
  
  In this blog Laurens van Houdt, Product Specialist at I&L Biosystems BeNeLux, guides you through the rules and procedures.

Osmolality in the EU

Equipment
An osmometer to measure the Freezing Point depression typically consists of:

• An appropriate sample container
• A means of cooling the sample
• A temperature-sensitive resistor (thermistor) with an appropriate device to measure current or potential differences. The device needs to be able to indicate a temperature depression or indicate the osmolality values directly; a means of mixing the sample and/or inducing solidification when supercooling occurs.

Procedure: calibration

1. Prepare the reference solutions as specified in table 2.2.35.-1 as necessary, using dried sodium chloride R. You may use commercially available certified solutions for osmometer calibration with values equal or similar to those listed in table 2.2.35.-1.
2. Calibrate the equipment according to the manufacturer’s instructions using water R to determine the zero value and at least 2 of the reference solutions listed in table 2.2.35.-1. Confirm the calibration using at least one additional reference solution with a known osmolality (see table 2.2.35.-1).
3. Select a reference solution preferably with an osmolality within ± 50 mOsm/kg of the expected value for the solution to be examined or close to the center of the expected osmolality range of the solutions to be examined.

It is recommended that the reading is within ± 4 mOsm/kg of the osmolality of the chosen reference solution.

Procedure: method

1. Rinse the sample container with the solution to be examined before each measurement.
2. Program the device inducing the solidification to start at a defined temperature below the expected Freezing Point of the solution to be examined.
3. Introduce an appropriate volume of the solution to be examined into the sample container according to the manufacturer’s instructions and start the cooling system. The equipment indicates when the equilibrium has been reached. Perform the test under the conditions (cooling temperature and volume) used to calibrate the equipment. Depending on the type of equipment, the osmolality can be read directly or can be calculated from the measured Freezing Point depression.

The test is not valid unless the measured osmolality of the solution to be examined lies within the calibrated osmolality range.

 
Osmolality in the US

Apparatus
The apparatus, an osmometer to measure Freezing Point depression, consists of the following:

• A means of cooling the container used for the measurement
• A temperature-sensitive resistor (thermistor) with an appropriate device to measure current or potential differences. The device may be graduated in temperature change or in osmolality and a means of mixing the sample.

Procedure

1. First, calibrate the instrument by the manufacturer‘s instructions.
2. Confirm the calibration of the instrument with at least one solution from table 1 so that the osmolality of the standard solutions lies within 50 mOsm/kg of the expected value of the test solution or the center of the expected range of osmolality of the test solution.
3. The instrument reading should be within ±4 mOsm/kg from the standard solution.
4. Introduce an appropriate volume of each standard solution into the measurement cell as per the manufacturer‘s instructions, and start the cooling system. Usually, the mixing device is programmed to operate at a temperature below the lowest temperature expected from the Freezing Point depression. The apparatus indicates when the equilibrium is attained.
5. If necessary, calibrate the osmometer, using an appropriate adjustment device so that the reading corresponds to either the osmolality or Freezing Point depression value of the standard solution shown in table 1. (Note: if the instrument reading indicates the Freezing Point depression, the osmolality can be derived by using the appropriate formula under osmolality.) Repeat the procedure with each test solution. Read the osmolality of the test solution directly or calculate it from the measured Freezing Point depression.

Key differences between EU and US:

• The EU requires a zero point calibration for osmolality.
• The EU requires calibration using at least 2 reference solutions.
• The EU recommends rinsing the sample container with the solution to be tested.

Sources: 
Chapter 2.2.35. of the European Pharmacopoeia (Ph. Eur.)
Chapter 785 of the United State Pharmacopoeia (USP)

Do you recognize this? Your research is going well. The results are looking good and you are about to finalize your valuable work. But then you discover that your osmometer is dated and it does not comply with the adapted regulations. It even causes your workflow to become non-compliant. Your workflow reached its Freezing Point.

In this blog Erik Janssen, Product Specialist at I&L Biosystems BeNeLux, tells you all the ins and outs about osmolality and its regulations and compliances. This way you can prevent your workflow from freezing and warm up your knowledge on osmolality.

What is the risk of using a dated osmometer?

First let us take a closer look on what can happen if you are using a dated osmometer.

• Your workflow can become non-compliant:
  Regulations change and you must keep your equipment up to date to comply. An older osmometer may no longer be compliant with current regulations such as GMP, EU annex 11 and 21 CFR part 11.
• You need more sample than necessary:
  Older osmometers need more valuable sample material. New osmometers require as little as 20µl to test the osmolality of a sample. This way you can preserve more of your precious sample.
• More downtime:
  Osmometers do not live forever. As your osmometer ages, parts wear and the chances of it breaking down are more likely. In time spare parts become both harder to get and thus more expensive the older your osmometer is. As a consequence, the maintenance on your osmometer becomes more and more difficult. In the worst case scenario it will stagnate your research.
• Longer lead time:
  Older osmometers are more labor intensive, need more frequent calibration and new users need more training to use them. All the while time is more and more precious.
• Non-compatible to your laboratory:
  Current laboratory equipment is becoming ever more complex and sophisticated. Many systems can be connected to laboratory information management systems. Dated devices are often not able to connect to these programs and become non-compatible. Having to export data manually is both time consuming and prone to errors.
• And last but not least: older units have no Network Time Synchronization.
   

How do you recognize a dated osmometer?

• The machine is 7 or more years old.
• Your machine has been discontinued more than 5 years ago.
• You experience frequent recalibrations or malfunctions.
• A technician may mention the age during maintenance or repair.
   

How can you prevent your workflow from freezing?

• Yearly preventive maintenance.
• Replace your osmometer in time.
• Reserve budget for quick replacement.
• Have a backup osmometer just in case.
• Keep yourself up to date about the current regulations concerning osmometers.
   

The benefits of a new osmometer:

• Supports 21 CFR part 11, EU Annex 11 compliance and the Pharmacopeia testing guidelines.
• Improved workflow and short test times so you can maximize your productivity.
• Easy to use, training is almost unnecessary.
• Wide operating range.
• Many connectivity options.
• Small sample requirement.
   

Now that you know all this, the most important question to ask yourself is: does your workflow still comply when it comes to osmolality? Or is it reaching its Freezing Point?

Check out the osmometers from our partner in osmolality: Advanced Instruments. We know you will have state of the art osmometry equipment. The osmometers from Advanced Instruments meet the latest requirement on data integrity and security for your results. Advanced Instruments has over 60 years of experience and is an early pioneer in the field of osmometry. With all that experience, they have become a trusted, valuable reference in the science of osmolality testing.

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