LogD – Shake Flask
This assay is used to determine the LogD of a test article at pH 7.4 using the shake flask method.
Required from Customer
- Either a minimum of 300 µL of test article at 10 mM in DMSO, or 5 mg of powder
- Exact molecular mass of test article and its salt form
- MSDS or handling and storage information, e.g., light sensitive, store at -20°C, etc.
- The measured LogD for testosterone (internal control) at pH 7.4
- The measured LogD of test article at pH 7.4
- Test article and testosterone equilibrated at 100 μM total concentration in equal volumes of phosphate buffer and water-saturated octanol
- n-octanol: phosphate buffer at pH 7.4
- Single incubation of test article (n=1)
- Mix samples for 1 hour at room temperature, then allow to sit for 1 hour at room temperature
- Sample each phase in duplicate
- Prepare serial dilutions of the organic and aqueous layers
- Determine the concentration to the test article at each dilution, using a generic LCMS/MS method with a minimum 6-point calibration curve Assay QC
- The LogD of testosterone must be between 3.0 and 3.4 for the test article’s LogD to be accepted
- The results from this assay are sent to the sponsor in the ExpressPlus report format, which may include graphical representations of data and comparison with historical data for reference articles.
- The LogD value is dependent upon the temperature of the buffer and octanol. The assay is performed at room temperature; we neither monitor nor control the temperature of the aqueous and organic phases.
- This assay can determine the LogD of test articles between approximately -2.0 and 5.0. Data outside this range will be reported as >5.0 or <-2.0.