Chromatography Forum

I am working on a method to analysis Adenosine, s-adenosylmethionine, s-adenosylhomocysteine in plasma by LC/MS. I am using Bond elut PBA to extract Adenosine, s-adenosylmethionine, s-adenosylhomocysteine from plasma. I have very good sensitivity for pure adenosine standard, 100 times higher than that of same concentration of s-adenosylmethionine, s-adenosylhomocysteine. However, the adenosine concentration from a plasma sample is very low, I will detect 0.004-0.007 umol/L, and the reference paper has adenosine concentration of 0.27umol/L. While data of s-adenosylmethionine, s-adenosylhomocysteine matches to what reference paper’s value very well. Since they all have similar structure, I will assume they have the similar extraction recovery. Any of suggestions? Thanks

Since they all have similar structure,

Yes they have similar structure but they are not exactly the same. It is the small differences in structure that allow chromatographers to separate the compounds.

I will assume they have the similar extraction recovery

This is a dangerous assumption. You must test the extraction recovery for each and every compound, preferably in your sample matrix.