| Author | Message | ||
     Erik Skibsted |
Dear Fellows I am currently working with a BOMEM MB160 equipped with the PowderSamplIR device. I measure powder samples in 20 ml glass vials through the bottom of the vials. I am thinking about testing BOMEMs new SpinningVial device. If anyone has some experience with different systems and sample presentation of powder samples I would bey delighted if they would share that with me. I am most interrested in small e.g. 1 gram and less powder samples of pharmaceutical powders. | ||
| interlab |
Erik : The powder samplir is very good for measure powder in vials. The problen can be if you need measure more area to the sample. For it you have a new Spining Vial device, where the measuring is make in the side of the vial, where the glass is more homogeneus, and the vial is moving. If you need measure little amount of sample you can move the spining accesory and put the vial horizontal, same as powder samplir. Fernando Morgado | ||
| Chan Chee Hoy |
Dear all, I'm currently working on a Perkin Elmer FT-NIR for ID testing of Pharma raw materials. Most of the raw mat are in powder forms. And method development went well with protein, carbohydrate products. But when it came to developing library for electrolyte salts i.e NaCl and KCl; I just couldn't develop 2 methods that distinguish the 2 materials. Overlapping occurred - software didn't recognise both materials. Can someone give a hand? Many thanks, Chan | ||
| David W. Hopkins (Dhopkins) |
Chan, There are times when you just have to accept that NIR cannot do everything. When a compound does not have C-H, N-H, O-H, S-H groups, or even C-O and C-N links, you are in trouble. In the cases of salts, there are sometimes spectral differences that seem to suggest that some discriminations might be possible, as in phosphates, nitrates, chlorates, etc, where at least you still have some NIR-active groups present. Different hydrates may also be included in this group, although I have not tried to include these in a discrim model. In the case of NaCl and KCl, the bands you see seem to be related to the method of manufacture. Commercial KBr also looks very similar. Yet you can obtain IR grade KBr that lacks essentially all NIR features. I believe these bands are due to OH- radicals incorporated into the crystal lattice instead of Cl-. The bands are apparently not due to H20, because even treatment at 230C for 3 hours does not change these bands. I would be interested if anyone has any references or further information about these bands. Anyway, it may be possible for you to create a halides group that can be discriminated reliably in your library. Then any further discrimination would have be pursued by another method. | ||
| Stephen Medlin (Medlin) |
Chan, Just a quick response re. measuring electrolyte salts in aqueous solutions. First off, most electrolyte salts are transparent in the IR/NIR (hence their use in Mid-IR). There have been several papers published on indirectly measuring these electrolytes by perturbation of water bands: Lin & Brown, Anal. Chem. (1993), 65, 287 Lin, Zhou, Brown, Appl. Spectrosc, (1996), 50(4), 444. Several other papers by Brown, et al. A big requirement is temperature effects which can shift the water band also. In fact this temperature effect can overwhelm the electrolyte effect. This requires either thermostatting the sample or modeling the temperature effect. Of course, these electrolyte measurements were done in aqueous solutions, so I'm not sure how well this effect would occur in your samples, but this may help at least. |