GLP-compliant water solubility testing according to OECD Test Guideline 105 provides a fundamental physicochemical endpoint and is a key determinant in the assessment of environmental fate, ecotoxicity, bioavailability, and hazard classification. Water solubility plays an important role in regulatory frameworks such as REACH, the Biocidal Products Regulation, EU Pesticide Regulation, EFSA authorization, as well as in the approval of pharmaceuticals by the EMA.

Selecting the Appropriate OECD 105 Method

OECD 105 describes several experimental methods for determining the solubility of substances in water. The choice of method depends mainly on the expected solubility of the substance and its physical and chemical properties.

Column Elution Method

·      For pure substances (solid and organic)

·      With low water solubility (< 10 mg/L)

·      Test principle: The aqueous eluate over a suitable column is collected until equilibrium conditions are reached.

Shake-Flask Method

·      For pure substances and mixtures

·      With a water solubility (> 10 mg/L)

·      Test principle: The concentration of the dissolved substance is determined after excess of the substance has been mixed into water and agitated until sufficient equilibration.

Flask Method (Slow-Stirring)

·      For pure liquid organic substances and mixtures

·      With poor water solubility (< 10 mg/L)

·      Also suitable for volatile substances

·      In accordance with the official ECHA guidelines (Guidance on IR&CSA, Chapter R.7a)

·      Test principle: Same as Flask Method, but using gentle stirring to establish equilibrium in order to minimize practical difficulties that could occur with challenging test items.

There is no single method that is equally suitable for every substance. Before starting a study, LAUS evaluates the available information on the test item. The aim is to generate reliable and reproducible experimental water solubility data in accordance with the applicable OECD guideline and GLP requirements.

At the client's request, tests can be tailored to specific requirements, as for example solubility at various pH values and temperatures.

Testing of Poorly Soluble and other Challenging Substances

LAUS has experience in testing substances that require specialised study design based on scientifically justified experimental approaches.

• Our state-of-the-art equipment ensures the lowest possible limit of quantification (LOQ).
• For mixtures, multi-constituent substances and UVCBs, an appropriate individual analytical approach can be developed.
• Slow stirring can minimise effects like emulsion or foaming, volatilisation, fine particle formation and therefore support reliable equilibrium conditions.
• For metals and sparingly soluble metal compounds, we apply OECD GD 29.
• For nanomaterials, we offer OECD 318 testing to investigate the dispersion behaviour in different environmental media.
• For silica, we have a bespoke system that determines silica solubility based on the Tyndall effect.
• For very sparingly soluble substances, our tailor-made FlowExtractor enables solubility to be investigated under dynamic flow-through conditions.

GLP Water Solubility Testing for Regulatory Purposes

LAUS performs water solubility studies under Good Laboratory Practice (GLP) to generate sound experimental data for regulatory applications.

OECD 105 water solubility testing is relevant for:

·      REACH registration

·      Chemical safety assessment

·      Environmental Risk Assessment (ERA)

·      Biocidal Products Regulation

·      EFSA requirements

·      EU Plant Protection Products Regulation

·      Personal and Home Care Products

OECD 105 Water Solubility Testing at LAUS

Looking for a reliable laboratory for OECD 105 water solubility testing?

LAUS provides GLP-compliant water solubility determination for a wide range of substances. Our scientists are happy to discuss your test item, expected solubility and specific study requirements in order to identify an appropriate experimental testing approach.

Request a quote for OECD 105 Water Solubility Testing!

 

Frequently Asked Questions About OECD 105 Water Solubility Testing

What is OECD Test Guideline 105?

OECD Test Guideline 105 describes standardised methods for the experimental determination of the water solubility of chemical substances.

Why is water solubility important?

Water solubility is a key physicochemical property that provides important information about the behaviour of a substance in aqueous media, its environmental distribution and its bioavailability.

Which OECD 105 method is suitable for poorly water-soluble substances?

Depending on the properties of the test item, methods such as the Column Elution Method or the Slow-Stirring Method may be suitable for poorly water-soluble substances. The appropriate method is selected based on the specific characteristics of the test item.

Can LAUS test very poorly soluble or volatile substances?

Yes. LAUS has extensive experience with poorly soluble, volatile and other challenging test items and can apply appropriate experimental and analytical approaches.

Can water solubility be determined at different pH values?

Yes. Water solubility studies can be performed at different pH conditions and, where required, at different temperatures.

Are OECD 105 studies performed under GLP at LAUS?

Yes. LAUS performs water solubility studies according to OECD 105 under Good Laboratory Practice (GLP).