The Particle Articles

On September 26, Oksana Olkhovyk, Ph.D., Senior Scientist at Gateway Analytical presented a webinar focused for scientists working to develop oral drug tablets, semi-solid creams and gels, and medical devices such as transdermal patches. In this webinar, she discussed the benefit of Raman chemical imaging (RCI) when evaluating content and blend uniformity. During the webinar, specific question were asked from the audience. You can find the transcribed Q&A below.

For more details on the webinar, you can use the links below.

• View the webinar
• Download the presentation slides

1. Can RCI accurately measure drug concentration as low as 10 micrograms in a tablet ?
   Accuracy of the RCI measurement depends on the properties of the materials (i.e. whether analyte is Raman active material or not) and relative concentration of the analyte in the final formulation, which should be more then 1-5%. For some formulations detection limits should be established during feasibility study for accurate RCI measurements.
2. How small a particle can be measured ? What would be the accuracy of this measurement?
   The acceptance criterion for the Limit of Detection study can be done for Falcon II RCI system based on the theoretical capability of the instrument and utilization of NIST-traceable Raman active sizing standards.  Although it was shown for the Falcon II RCI system that a 500nm particle can be detected, it does not mean that it can be sized accurately with the required and desired accuracy.  Thus, the optimal limit of detection was established to be one (1) micron.
3. Along with Polymorph Identification can we also estimate the percentage of different polymorphic forms in a product or the percentage of crystalline and amorphous?
   A feasibility study and calibration curve should be established for each polymorph and applied to unknown samples for quantitative analysis.
4. How much time would it take to measure the thickness of multiple layers in a bead ?
   All RCI measurements are material-dependent. Usually a simple feasibility study should give a pretty good estimation of the time required to measure the thickness of multiple layers in a bead. For the data shown in the poster you can download it here.  The RCI acquisition over CH-stretching region was set to be 30-60 seconds, but for some formulations it may require up to 4 min depending on SNR requirements.
5. Does Gateway Analytical provide services to India and Asia?
   Yes, we provide our services worldwide.
6. How long does it take to have an entire Raman image for a tablet?
   All RCI measurements are material-dependent. Usually a simple feasibility study should give a pretty good estimation of the time required to measure entire tablet.
7. You combined the use of Raman and NIR for Content Uniformity. In addition to water being a poor Raman scatterers, how else would they differ?
   We try to develop material-specific methods and apply techniques that suits projects objectives the most. All techniques are material dependent and analytical techniques applied for each project are established for each customer during feasibility study.