How much of a solid is ordered
Many active ingredients can exist in an ordered crystalline form and in a disordered amorphous form, and often in several crystal forms. The amorphous part dissolves faster but is usually less stable, so its share affects dissolution, shelf life and processing. Milling, spray drying, granulation, compaction and exposure to heat or humidity can all change that share.
Where it is used
- Active ingredients and excipients
- Powder blends and granules
- Tablets, and powders from spray drying, freeze drying or milling
Typical tasks are screening the amorphous content after milling or spray drying, checking that a form stays stable during storage, comparing batches, and screening formulations early in development.
Rigid parts fade fast, mobile parts last
In rigid, ordered material the signal fades almost at once. In mobile, disordered material it lasts longer. Each solid form has its own characteristic behaviour, so a mixture can be described as a sum of reference forms, and the share of each is read from the signal. The powder is measured as it is, in a tube, without dissolving it.
A calibration with mixtures of known composition turns the signal into a percentage.
What it adds
- Non-destructive, so the sample can be kept and measured again
- No dissolution step, no solvents and little sample preparation
- Less dependent on the texture of the sample than some other solid-state techniques
- A quick screening tool that complements X-ray diffraction, calorimetry and solid-state NMR, and frees those techniques for the difficult questions
Points that matter in practice
- Excipients also give a signal, so calibrate on the real formulation and not on the pure active ingredient
- The lowest amount that can be quantified depends on the system. It should be established in your own validation and not taken from a general statement
- Reference forms are needed for a calibration, and sample history, temperature and humidity can change the form, so control them
- The method tells how much is rigid and how much is mobile. Naming a specific polymorph needs reference forms and, for a new one, a second technique
- For a regulated use, the method has to be validated for your product
From your powder to a routine method
Send or bring representative samples. MSY Consulting runs feasibility measurements, helps you prepare reference mixtures, and trains your team until the screening is part of your routine.
Let's talk about your application
Send an email describing your instrument and your application, and you will get a reply.
contact@msyconsulting.euMSY CONSULTING SAS · Wissembourg, France · LinkedIn