How far does your mass spectral library identify the compounds you have?  That is the usual reason for using MS so that you can match the compounds with a library of mass spectra.  Otherwise you have to find published spectra from NIST or in literature to match by eye - very time consuming.  The same is true of trying to match your compounds by using standards.  Terpenoids are such a complex and varied group of compounds you could try for years and never find a match, and many will not be available as standards in any case.

What plant extracts are you looking at?  You could start by looking at other analyses of the same plants (if there are any) which would at least give you a starting point.

some standards are available and you can try but in  actual confirmation try to correlate the results from other sources also.

Some terpenoids of different structure have almost identical mass spectra so identification by mass spectra alone is problematic.  If you cannot obtain pure standards (often the case) then try using the relative retention index (Kovat's Index) as an additional identifier.  If you use two different polarity columns and calculate the relative retention index for each column then this can make identification even more reliable.

Dear John

how we can use two different columns for terpenoids identification?

 Dear Ram,

What kind of sources.... please elaborate.

FTIR can be helpful in this matter or anything else?

Dear Valerie

thanks for your reply. I am working on Diospyros malabarica and some other plants of rosaceae and moraceae family. 

I worked on Diosprous peregrina and its good to know that on same genes work is continued... 

OK, so you would need to buy two columns. Say a BP 1 or BP5 (which are non polar, boiling point columns) Then something like a BP 20 ( on which compounds elute in polarity order).  You run your sample on each column and also a mixture of n-alkanes from about C-8 up to C-16. From this you can determine the retention index for each compound.  There is plenty of literature on how to calculate the Index. You know which compound is which from the mass spectrum.  There is plenty of literature on Kovat's Indexes or Retention Indexes ( same thing really) So you can look up the literature values.  Some library searches have a Retention Index data base as well as a spectral one.

The solvent system may be modified and change to elective the isolation. The best result may be obtained if suitable column with perfect adsorbent may be used.

Dear

Terpens are high diversity type of compounds. The GCMS analysis of these compounds especially triterpens and tetraterpens is more complicated. Due its high molecular weight, it may be have high boiling point which makes gcms analysis not sufficient for it. However more problems are known for their gcms analysis. When you try to match with standard library low similarity are usually gained. However try to match your results with different library and may find acceptable similarity.

Good luck

Dear Alisiddig

What type of other libraries? Can you specify?

Dear Ram 

I am also doing its DNA extraction and i am interested to use ISSR markers. But one problem exists DNA pallet is sometimes dark and sometimes red colour. Secondly i am using dry powder for DNA extraction. will it be helpful?If you ask i can send you the picture of DNA pallet.