how I can quantify my analyte without having standard

[mk12]

I do not have standard for my analyte.How Can i quantify it in my extract. This copd in not commercially available..what are the other options if there are any ...help will be really appreciated

[Kostas Petritis]

If your compound contains nitrogen you can use a CLND detector and use another nitrogen contain compound (caffeine is used most of the time) to plot the calibration curves... You'll be able to have an estinate at around +/- 10%. Of course you will have to separate your compound from other (nitrogen containing) compounds of your extract...

[Peter Apps]

Do you know what the analyte is ? What detector and chromatography are you using ?

Peter

[sassman]

Are there any compounds with similar structure available commercially? Preferably, the difference would be on a functional group that doesn't affect ionization much (assuming you are using ESI-MS?) (ie ethyl instead of methyl). The Sigma-Aldrich website has a nice little applet where you can draw the structure of your compound and do a similarity search. Of course, the response will not be exactly the same but a good approximation. If you have lots of money or have organic chemists at your disposal, you could have a custom synthesis done.

[bhuvfe]

CAD from ESA (see link below)?)?
http://www.esainc.com/products/type/hpl ... /coronacad

If you are not looking for ppb it should work....

[mk12]

my analyte is aloesone( 2-acetonyl-7-hydroxy-5-methylchromone) and i am using shimadzu IT-TOF. and shimadzu LC.

[lmh]

Am I right in thinking aloesone is a flavonoid of some sort? If so, try the indofine chemical company, or apin chemicals; they may have something at least similar.

The bottom line is that if you're using electrospray LC-MS, you cannot quantify properly without some sort of standard.

Even with a similar compound as standard, I would prefer to quote results not as micromoles, but as micromoles-based-on....

Good luck!

[Kostas Petritis]

For absolute quantitation you will need to synthesize this compound. Synthesizing something similar might work or not as when you change the hydrophobicity of your compound it's ionization efficiency maybe significantly altered (i.e. going from Gly to Ala or from Ala to Val you do not change any functional groups but you get completely different electrospray responses).

[sassman]

I found a patent detailing the purification of aloesin from aloe vera:

http://www.freepatentsonline.com/6451357.html

It seems to have a similar structure to your compound. They claim that the product obtained by crystalization is of high purity. Perhaps it is possible to convert aloesin to aloesone?

[gpronger]

mk12;

My question would be; how accurate do you need to be? You can estimate a concentration based upon the total ion area versus an internal standard (as close chemically as you can find). My experience with EPA type work is that the estimated concentration is not likely to be more than about a factor of 4 off (a 1PPM being 4PPM), the closer your internal standard the better.

If your purpose is comparison between samples, this may be sufficient until you can sort out a standard source.

Greg