| Author | Message | ||
     harisenthil (Harisenthil) |
Can NIR idendify Inorganic Salt contaminations like Sodium chloride, Potassium bromide, carbonate, bi carbonte etc in Pharmaceutical Drug samples. Is it necessary to address the related impurities in Calibration/Model development for a Drug sample quantification. If the Calibration doesnt address the related impurites(Inorganic salts and/or Organic degradation products etc) and if the incoming sample is contaminated with related impurities, will the Quantification using the calibration is valid? Regards Hari | ||
| Bruce H. Campbell (Campclan) |
I will answer only the first of your questions and leave others to give a more complete answer. Remember that the bands in the NIR region from organics are overtones and combinations from the fundamentals in the mid IR Region. If the materials don't have a fundamental vibration, there won't be any in the NIR region. However, materials that have a strong ionic character can form spheres of hydration with water. This causes the band for that water to shift to slightly longer wavelengths, usually around 1940 nm. Some have claimed to be able to differentiate between salts when using this shifted water band. In my mind, there is not yet an ablsolute answer. | ||
| Gabi Levin |
Hi Harisenthil, I agree with Bruce about the issue with spectra of inorganic ionic substances. The subject of influence on the water band could possibly be useful if there is interaction between water and the ions. In the solid state, as tablets, the moisture in the tablet is too low in my opinion to "react" with the solid crystals of the inorganic impurity. So now we are talking about a low concentration, (impurity), a tertiary (not even secondary) effect, and we expect to make use of it, welcome. If, however, the impurity happens to be such a crystal that has crystalization water as part of the crystal structure, then we can expect to see the presence, even if a small one, pending on impurity concentration, of absorption peak in the 1390nm area, and possibly, if we know where the crytalline water absorb in the different inorganic crystals, we might be able to use it to detect these inorganics, all said with great caution. To the second question - despite the fact that the inorganics do not absorb, they scatter, thus, to have a robust and reliable calibration they need to be part of the calibration set. It is even more important if there are inorganics with crystalization water. It is then necessary to go through sufficient number of lots to represent the possible variability in that contamination. As for degradation products, being organic in nature, and usually being the result of "aging" of a drug product,they should be part of the calibration, if you expect them to be there when the intended measurement will be done. Hope this was some help. Best to all, Gabi Levin ([email protected]) | ||
| harisenthil (Harisenthil) |
Gabi Levin and Bruce, Thanks for you valuable inputs. I understand from your input that the NIR spectrum is the overtones and combination bands of mid IR. However some people say that the salt like KBr and KCl does not have dipole moment and hence they wont have spectral patern in NIR and the salts like Sodium Bicarbonate, Bi carbonate, Sodium sulphate has dipole moment and will have NIR spectrum. If the substance like Sodium Bicarbonate etc, which has got dipole moment, then in that case they should be mid IR active as well. I have went thro the USP and BP where all these Inorganic salts are idendified by the classical techniques and not by mid IR technique. Please help me. Regards=Hari | ||
| Bruce H. Campbell (Campclan) |
Hari, In my earlier response I should have said there are two requirements, not one, for a material to have a spectrum in the NIR region. The first is that of having a fundamental in the mid IR region. The second is related to the intensities of the overtone and combination bands. Covalent hydrogen bands have intensities much larger than expected, but have been explained quantum mechanically. Other species have bands in the NIR region, for example carbonyl close to 1900 nm but is of much lower intensity and also near the very large water band. This raises difficulties in using that carbonyl band in the presence of water. So the TWO conditions are: have a fundamental band in the mid IR AND sufficient intensity in the NIR region. Bruce | ||
| Lois Weyer |
Inorganic ions such as carbonate, sulfate, and bicarbonate definitely have distinctive mid IR spectra and also near IR spectra. The near IR spectra are weak, however, relative to molecules with protons, especially water. I've used the carbonate band in the near IR in an analysis. Lois | ||
| harisenthil (Harisenthil) |
Mr. Lois Weyer, For which type of analysis you have used the carbonte band in NIR. Can it be used for Qualification of an incomming drug contaminated with carbonate? can it be used for quantification of drug contaminated with carbonate? As explained by Bruce, the intensities of carbonyl is very week compared to that of covalent Hydrogen Bond? regards=Hari | ||
| Gabi Levin |
Hi everyone, Lois is right, these inorganics do have weak, and mostly broad bands, and the word weak is probably key to it, because it would be one thing to use it when the carbonate and sulfate is in a high concentration, (and I used it in some OTC work) but bear in mind the question was about those being contaminants, i.e., very low %, and that combined with the peaks being weak, broad, (good chance the main compound absorbs in same region just as much as the carbonate or more) makes the task of identifying these contaminants by NIR practically impossible. Thanks, Gabi Levin | ||
| Vitas Svedas |
The NIR is hardly a good mean for detection of inorganic salt impurities, because a prevailing part of NIR absorption is made-up by overtones of hydrogen vibrations (C-H, O-H, N-H bonds). If to consider alternatives, atomic emission spectroscopy (AES) is one of suitable means. Laser induced breakdown spectroscopy (LIBS), the modern branch of AES, is capable for multi-element analysis (in the UV/VIS). Alkali metals and halogens are included. LIBS spectroscopists declare on-line analysis with ppm detection threshold. Pharmaceutical samples are in the field of LIBS. Probably this information will be useful for you, Harisenthil | ||
| Tejaswath (Tejaswath) |
Dear all, when we are aiming for calibrating active ingridient in drugs , we must definetely take care of impurities in drugs most impurities will have covelant bonds - strong response in NIR region (it may not important for inorganics) In that case will it be okay for if we did for total impurities instead aiming inorganics etc. Thanks |