Dear friends,

I have got a lot of assays to performed on plasma samples to quantitate Acetylsalicylic acid and salicylic acid.
I already have an analytical method with fluorimetric detection. However I would like to try to develop a new method with LC-MS/MS technique in order to improve limit of quantitation value.
Does somebody here know a described method to analysed those compounds by LC-MS/MS or could give me few informations for method development?

I thank you in advance for your answer.

Delphine

MS needs volatile buffers, otherwise you can use the same method. With MS you should be able to speed it up, using a shorter column.

Dear anonymous,

Thanks a lot for your answer.
I am working on the development of the method at the moment : detection of ASA and SA by MS/MS seems to be good by the problem is that ASA is partly destroyed in the source and transformed in SA. So I hope that I will be able to reach the limit of quantitation I am looking for.

OK, this means that you need to keep ASA and SA separated by chromatography to get good results by MS/MS. May I assume that the method with the fluorescence detection provided this?

In case of our fluorimetric HPLC method, in order to avoid problem of partial and unpredictable destruction of ASA to SA during analysis and in order to improve the limit of quantitation for ASA, we perform in-line post-column ASA hydrolysis to SA (with concentrated sodium hydroxide).
So ASA and SA were separated on chromatographic column but detected peaks were actually both SA.

It could be the same principle with MS/MS detection if ASA is transformed in SA in the MS source. In this case, it is clear that chromatographic separation of ASA and SA before MS/MS detection will be essential but possible.
However, it seems that the transformation of ASA to SA in source is not total, so I hope that we will be able to develop a quantitation method even though.

Today, we worked to select the ions (parent and daughter) of ASA and SA and tried to optimize parameters for MS/MS detection in solvant composed of Formic acid 0.05%/MeCN 50/50.
Next monday, we will try injections on X-terra MS C18 column using the same transition in MRM for ASA and SA MS/MS detection.
We will see if transitions are stables and detection as sensitive as we want.

Hi
I am working on Acetyl salicylic acid,can you tell me the Parent and product ion ,as they are very smal Mo.Wt