I have performed LC-MS for an unknown polymer sample from fermentation broth. Acetonitrile:water mobile phase of 50:50 (vol:vol %) was used. MS data analysis was performed for a single peak which was confirmed to be polymer in the chromatogram which was sent directly to MS. (single peak at 4 to 5 min retention time)
If chloroform's molecular weight is 119 g/mol I should be getting a peak at around 118 in case of negative m/z spectra and the polymer peak should be a single peak where as I am getting a range of peaks.
Attachments : ccl ms is for the polymer sample dissolved in chloforom while cpe ms represents extracted polymer sample.
Hello dear, you have to analysis every peak and according to m/z value assign a structure, you can observed, which are the differences in m/z between peaks since it is related to repetitive units of the polymer. Furthermore if you has employing others technical of characterization, you can confirm what type of polymer have you, and the MS-HPLC analysis will be easy, because you can organize the estructure account the m/z ratio.
If it is polymer then the difference b/w two adjacent peaks should be MWt of your monomer, which you used for polymerization.
Sivananth,
I am a bit confused about your question. You mention chloroform and its mass spectrum. You can find that on-line but I am not sure waht this has to do with your unknown. You have separated the 'polymer' on the HPLC and have the mass spectrum of the compound eluting between 4 and 5 minutes. As Edwin mentioned you now have to analyse this and come up with a structure that is consistent with that mass spectrum. Other analytical techniques may be required to confirm the identity of your unknown.
Sreenath indicated that the difference between two adjacent peaks will give you the molecular weight of the monomer that the unknown 'polymer' was composed of. This might be true for adjacent peaks in the chromatogram but it is not true for the peaks in your mass spectrum.
Thanks everyone , Its biologically synthesized bioplastic and I have analysed the sample for NMR spectrum and FTIR spectrum and I did come up with a rough structure. Dear John Hiltz, i understand it was that I didnt think about the elution of peaks my bad. I will take your suggestions nto account in predicting the molecular mass and the structure . thank you
If im not wrong I understand that when the polymer is broken down into monomer units and the respective m/z peaks will be repetitive and so their intensity would increase . In which case from NMR and FTIR I have deducted that the polymer is a 10 Carbon molecule and so I suppose the m/z peaks should also be ten or is it usual that there might be more than 10 peaks . Im sorry it is just I read too many related articles and watched videos which are too confusing. They put forth contradicting statements.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry
- Polymer Chemistry