We want to determine curcumin in mouse plasma after subcutaneous administration of some formulations. The idea was to perform the determination by HPLC-MS. However, we have been having a problem with the suppression of the response of the internal standard (deuterated curcumin; the standard is OK because other tissues have a good response). Plasma sample preparation was done with 50 µl volume and protein precipitation and extraction with three volumes of ethanol (centrifuging and rescuing the supernatant between each extraction). Afterward, SPE is performed on C18 cartridges to maximize cleanup. Other tissues, such as nodules or hind footpads, respond well to this extraction process, which we believe is the most optimized. What can we modify to reduce the ion suppression problem? We have modified the separation method without much success. Thank you.
Noel W Davies Thank you, Dr Davies. When you say "do a full scan acquisition," do you mean to search which compounds are eluting at the same retention time as the analyte? Do you think that simply performing a longer run would move the interference from the retention time? Thanks
I suggest using phree-phenomenex (bimodal/phospholipids and protein removal) protein precipitation plates...This will remove the abundant large molecules of serum such as proteins (albumins, globulins...and phospholipid derivates)...with this, you may combine protein precipitation and spe clean-up into a single prep step...In addition, MS/MS fragmentation and using alternative ions for your SRM acquisition may improve specificity and give more non-interfered spectra...If sensitivity is low I also recommend nitrogen evoporation followed by buffer exchange and internal standard normalization approach for absolute quantification...for hydrophobic compounds such as curcumin I also use APCI instead of ESI to get a more intense signal if your configuration is applicable to implement...
Good luck
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