Mr. Vasconcellos,

The quantification by Fs does not provide reliable quantitative information, due to a set of reasons associated with the limitations of the Fs spectroscopy (high LODs, respectively, LOQs; error contribution, due to data-processing of experimental outcomes; low selectivty, et cetera, et cetera...)

Reliable, accurate, precise, exact, seloective and sensitive analysis can be carried out only by mass spectrometry; furthermore using our own-authored (to me and my co-author's theory according to the authorship shown, below) innovative stochastic dynamic theory and model formulas for processing of experimental measurable variables.

Please, consider detail on references [1,2] and reference sections, therein.

[1] Stochastic Dynamic Mass Spectrometric Approach to Quantify Reserpine in Solution; Bojidarka Ivanova, Michael Spiteller Analytical Chemistry Letters, 10 (2020) 703-721; Received 13 Oct 2020, Accepted 16 Dec 2020, Published online: 28 Jan 2021 Download citation https://doi.org/10.1080/22297928.2020.1865834

[2] Steroids, 164 (2020) 108750 Stochastic dynamic mass spectrometric quantification of steroids in mixture — Part II; Bojidarka Ivanova, Michael Spiteller

P.S. Perhaps, the abbreviation MDA shown in your posting denotes malondialdehyde. I hope, that you do not quantify amphetamins by Fs (MDA: 3,4-Methylendioxyamphetamin?)

There are several methods are available for the determination of MDA levels. For the determination of MDA, you may visit the following useful link:

Article Free malondialdehyde determination by HPLC applied to micros...

Article Determination of malondialdehyde in traditional fish products by HPLC

https://www.jlr.org/article/S0022-2275(20)41949-2/fulltext