Chung Liang Lim

5 Questions 16 Answers 0 Followers

Questions related from Chung Liang Lim

HRMS speculated molecular formula did not match with the NMR spectral data. What is the reason behind?

I have recently isolated an unknown compound with molecular weight of 522 (m/z value = 523). The UV absorption was observed at 263 nm. I have accessed the database to search for any known...

20 January 2015 1,660 10 View

Recently, I used LC/MS to measure the molecular weight (m/z value) of my isolated compounds. Why did my compounds not ionize well in negative mode?

I have isolated several compounds recently and tried to measure their molecular weight or m/z values using LC/MS instrument in order to elucidate their chemical structures. However, I found that...

14 November 2014 2,548 6 View

Recently, I have isolated a novel compound with slight impurity. Shall I purify it or proceed to NMR to disclose its structure prior to purification?

I have isolated a novel compound from fraction library and there is a slight impurity which is detected using LC/MS analysis, where a small ion peak is detected besides the molecular ion peak....

21 October 2014 6,509 19 View

Can anyone assist me with identifying the novelty of an isolated indolic enamide?

I have searched through Dictionary of Natural Products and found a reported compound. The structure of my compound was found to be identical with the reported one. However, there are some slight...

09 September 2014 2,079 10 View

How to determine the novelty of isolated compounds?

I have isolated a few fatty acid derivatives recently. After taking all NMR measurement, I have assigned the planar structures but I am unsure whether these fatty acids are of novel or known...

17 June 2014 2,277 5 View