Limonin analysis

[oscarBAL]

Hello every one, I am trying with a procedure for Limonin analysis althought the HPLC method is not dificult I would like to see a good procedure for the Sample Treatment, I think that my SPE procedure is not the best and I would like to improve it.

As allways I would like to read your opiniom on the matter.

Thanks and Regards.

Oscar.

[Uwe Neue]

I'd be glad to help, but you need to provide more info. What other stuff is in your sample besides the limonin? What is the SPE procedure that you are using now? What improvements are you looking for? ETC...

[oscarBAL]

Thank Uwe, we want to reduce the time of sample preparation, for some reason is dificult to get good reproducibility among SEP batches, we are using C18 SEP 360 mg, we take the concentratade orange juice and reconstitude them with a H2O: MeCN 70:30 and then we precondicionate the cartridge with MeCN, 2.5ml, H2O 2.5ml and then we load with 2,5ml of sample, rince with water and eluete with MeCN.

We would like to know what is the most apropiated cartridge for this and what it should be the optimus flow for elution and preaconditioning. We think that the kind of cartridege is not the best.

Thaks and Regards.

Oscar

[Uwe Neue]

In principle, the method that you are using should work. It is correct that you need to watch the flow rate. If you have variable recovery, too high a flow rate during any step in the procedure could cause a problem, but especially during the loading step. Flow rate variation can be caused by a setting of your vaccum, or by the particle size distribution of the packing.

If you want to explore another packing with a higher reproducibility, I recommend the Oasis HLB packing. You will need to select a smaller weight compared to your silica due to the density difference between silica and the polymeric Oasis HLB. The difference is about 2 fold. If you use Oasis HLB, you can use the same procedure, but replace acetonitrile with a 1:1 mixture of methanol and acetonitrile.