| Author | Message | ||
     David Semmes (dsemmes) Junior Member Username: dsemmes Post Number: 9 Registered: 6-2010 |
In the past, I often used standard scintillation vials for pharmaceutical excipients, blends, and coated sugar spheres without detecting any experimentally significant difference attributable to the vial. However, I did once detect a spectrally small, but experimentally significant difference that I positively attributed to differences between vials. It biased the quantitative analysis of one of the components. Since then, I�ve primarily used ~ 10mL, 22mm OD glass vials from Bruker, part number IN440-005, again without ever detecting any experimentally significant differences I�ve attributed to the vial despite commonly measuring replicates of individual vials and sometimes comparing replicate vials. Bruker identifies them as �vials with flat bottom,� but I don�t know their justification for that. These vials are a bit awkward in that they don�t have a screw top, but they do create a hermetic seal like GC headspace vials. I�ve monitored the spectra of hydroscopic samples in sealed vials for a year without detecting a change larger than ~ 0.3% moisture in the ~5% moisture content. In all this work, I�m typically evaluating normalized and derivatized diffuse reflectance spectra, not unprocessed spectra. Hope this helps! Can anyone else comment on their experience with these vials? David | ||
| Sue K Baker (sue) New member Username: sue Post Number: 1 Registered: 1-2012 |
Bill and Dan, Were you able to find a supplier of glass vials, please? Sue | ||
| Bill Bramstedt (bramstedt) New member Username: bramstedt Post Number: 1 Registered: 8-2011 |
Dan, Were you able to identify better optical quality flat bottom glass sample vials with screw caps for a NIR identification test? If so, can you share the supplier? Regards, Bill | ||
| Shirley Liu (yjunhan) New member Username: yjunhan Post Number: 1 Registered: 7-2006 |
It is not necessary to use quarta, however for the vial glass bottom, the thinner, the better. and if you have a gold probe and be fit into the vial to get the background, the glass used doesnot matters that much. | ||
| Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 42 Registered: 9-2001 |
Gabi - I tend to agree with you that a flat bottom is probably unnecessary for most "in-vial" analyses, especially for "easy" ones like moisture. On the other hand, for difficult, or for marginal analyses, the little bit of extra benefit might just make a difference. For this reason, I'd like to know if vials with optically flat bottoms are available, because it would be a good piece of information to have in my mental "toolbox". Also, don't forget that while some people drive Chevrolets, some drive Cadillacs. It may be that the people looking for the flat-bottom vials simply feel more comfortable with the feeling of extra quality, and are willing to pay for it, whether or not there is objective benefit. \o/ /_\ | ||
| Gavriel Levin (levin) Junior Member Username: levin Post Number: 10 Registered: 1-2006 |
Hi, I have already pointed out that it is not necessary to have a flat bottom, we do moisture analysis at speeds of 300 per minute in Roche Basel through the side wall of the vials, and the side walls are far more reproducible than the bottoms and this has been operating for several years by now without a problem. Dr. Lars Sukowski published his Ph.D. dissertation on this work and showed how well this can be done. The problem with optically flat bottom is that is against the nature of making glass products. For more information anyone with interst is invited to write to me. Thanks, Gabi Levin Brimrose [email protected] | ||
| Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 41 Registered: 9-2001 |
Another thought, Dan: check with the manufacturer of the snap-top vials; it's possible they also make screw-top vials, but didn't advertise them in the catalog you saw. As for storage of samples, etc: it depends mostly on the nature of the samples and how well they keep in storage under the conditions you store them in. Many samples types keep well except for gain or loss of moisture, but you know (or should know) the behavior of your samples better than anybody else. Howard \o/ /_\ | ||
| Howard Mark (hlmark) Senior Member Username: hlmark Post Number: 40 Registered: 9-2001 |
Well, if anybody knows where vials with optically flat bottoms can be had, let us all know. Apparently it's becoming in demand, since we now have two requests for vials like that. \o/ /_\ | ||
| Daniel Szeto (dan_szeto) New member Username: dan_szeto Post Number: 1 Registered: 6-2006 |
Hi NIR Community Members, I need your help in locating better optical quality flat bottom glass sample vials with screw caps for a NIR identification test of a powder blend. Currently, 20 mL scintillation glass vial are used as sample vials for our identification test. However, we are concerned about the gross physical and optical imperfections observed on the bottom of the scintillation vials. Uneven thickness and concentric rings were observed on the bottom of each vial. Scanning a sample successively at about 120 degrees rotation about its vertical axis showed significant differences in the spectra. I have located a source of better optical quality flat bottom sample vials with snap caps, but our laboratory prefers sample vials with screw caps. Our intention is to use the flat bottom sample vials with screw caps for scanning and also use the same vial for storing each original calibration sample for future re-calibration. What is the best practice for storing the calibration sample set? Are the calibration samples taken fresh from each bulk material prior to calibration and recalibration, if the original calibration samples are discarded after each calibration/recalibration? Thank you for your help. Dan Szeto | ||
| Gavriel Levin (levin) |
Hi Trixie, I can tell you that the vials that are being used for lyophilization are OK, we measure moisture through the side wall at a speed of 300 vials per minute as they come out of the lyophilizer without stopping in at least 2 such plants in the world. we prefer side looking because it is easier to make sure that the window on our nalayzer through which the vial is illuminated and light is colletced back into the analyzer stays clean, plus the walls are usually much more consistent than the bottoms. If you write to me directly, I will be able to provide more information. Gabi Levin [email protected] I hope this will help you. | ||
| Howard Mark (hlmark) New member Username: hlmark Post Number: 15 Registered: 9-2001 |
Trixie - especially when you want to calibrate for water, it's important that there be little or no water or -OH bands in the glass of the vial. Pyrex and other softer glasses do have appreciable amounts of -OH (from SiOH) in them. Quartz has less -OH due to its having been processed at higher temperatures than softer glasses. Even so, ordinary quartz has some -OH in it, and variations in that will affect the moisture readings. There is special NIR-quality quartz manufactured, but as you might guess, it's more expensive than other types of quartz. Flat-bottomed vials are preferred for their better optical quality, causing less distortion of the beam. This will improve the precision of the measurement. Trixie, its the same with NIR as with cameras, hi-fis, and anything else you might buy: you'll pay more for quality. In this case "quality" translates into precision and accuracy of your results. So you can go with the less expensive vials, but then you should expect to have more trouble getting a calibration that won't be as good as one you could have obtained by spending a little more on the vials. Maybe you should do a cost analysis: the extra cost of the vials versus the value of the rest of the equipment, plus the fair rental value for your lab, plus your salary and overhead, plus the extra losses the company will incur from poor analytical results, and then see if the cost of the vials is appreciable compared to that. Howard \o/ /_\ | ||
| Trixie Tan (ttan) New member Username: ttan Post Number: 1 Registered: 5-2006 |
Hi! I'm planning to develop a quantitative chemometric model on powder samples using FT-NIR (for rapid measurement of residual water content, using Karl Fischer titrimetry as the primary method). Diffuse reflectance measurements would be done using an integrating sphere to measure powder through the bottom of a clear glass vial. I have heard that the type of glass (e.g., Pyrex, soda lime, etc.) affects the quality of the data and that vials from some vendors exhibit greater variability. Some people recommend using quartz vials, but I prefer to use something that is disposable (though I'm willing to pay for quality�). I have also heard that flat-bottomed vials are preferred for these types of measurements. My concern is that we are spending a lot of time and money to build a calibration model, and I want to use the best possible vial to acquire the data used in building the model. Do any of you have experience with different vials and, if so, can you recommend some vendors and vial types? Also, can you suggest some journal articles that include comparative studies of various vials? Thank you for your help! Regards, Trixie |