@article {Tiwaridmd.117.077073, author = {Ranjeet Tiwari and Deepak Ahire and Hemantha Kumar and Sarmistha Sinha and Siddheshwar Kisan Chauthe and Murali Subramanian and Ramaswamy Iyer and Ramakanth Sarabu and Lakshmi Kant Bajpai}, title = {Use of hybrid capillary tube setup on 400MHz NMR for quantitation of crucial low quantity metabolites using aSICCO signal}, elocation-id = {dmd.117.077073}, year = {2017}, doi = {10.1124/dmd.117.077073}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {Metabolites of new chemical entities can influence safety and efficacy of a molecule and often times need to be quantified in preclinical studies. However, synthetic standards of metabolites are very rarely available in early discovery. Alternate approaches such as bio-synthesis needs to be explored to generate these metabolites. Assessing the quantity and purity of these small amounts of metabolites with a non-destructive analytical procedure becomes crucial. Quantitative nuclear magnetic resonance (qNMR) becomes the method of choice for these samples. Recent advances in high field NMR (\>500 MHz) with the use of cryoprobe technology has helped to improve sensitivity for analysis of small microgram quantity of such samples. However, this type of NMR instrumentation is not routinely available in all laboratories. In order to be able to analyze microgram quantities of metabolites on a routine basis with lower-resolution 400MHz NMR instrument fitted with a BBFO room temperature probe a novel hybrid capillary tube set up was developed. To quantitate the metabolite in the sample an aSICCO method that introduces an internally calibrated mathematical signal was used after acquiring the NMR spectrum. The linearity of aSICCO signal was established using Ibuprofen as a model analyte. The limit of quantification of this procedure was 0.8 mM with 10K scans which could be improved further with the increase in the number of scans. This procedure was used to quantify three metabolites- phenytoin from fosphenytoin, dextrophan from dextromethorphan and 4-OH-diclofenac from diclofenac and is suitable for mini-biosynthesis of metabolites from in vitro systems.}, issn = {0090-9556}, URL = {https://dmd.aspetjournals.org/content/early/2017/09/21/dmd.117.077073}, eprint = {https://dmd.aspetjournals.org/content/early/2017/09/21/dmd.117.077073.full.pdf}, journal = {Drug Metabolism and Disposition} }