A double-cartridge SPE-HPLC-UV method for monitoring a humanfriendly anticancer in plasma: Ketoglutarate levels in metastatic carcinoma

We present a fully validated HPLC-UV assay for the concurrent quantification of
ketoglutaric acid and hydroxymethylfurfural, a ‘targeted therapy’ composition inducing a
synergistic metabolic distress to the tumoral microenvironment. The analytes were
exclusively extracted from the biomatrix via a combined-cartridge solid phase extraction
assembly. The method is based on derivatizing both analytes with 2-nitrophenylhydrazine
directed to their chemically divergent but commonly occurring carbonyl function. The
reaction is kinetically catalyzed. Acidifying the buffered eluate post-extraction is critical for
the feasibility of the reaction. The chromatographic separation is successfully accomplished
on octyl columns in less than 15 min at 330 nm using 0.028% TFAA-methanol-acetonitrile
(58:32:10, v/v) as eluant. The assay was validated using the concept of accuracy profile.
The selectivity of the method was demonstrated in pre- and post-dosed patients from a pilot
study. Quality control samples were prepared and analyzed during the routine use of the
method. Life samples collected from patients enduring oesophageal and breast carcinoma
with lung metastases were monitored for ketoglutarate in a trial to correlate its plasma
levels with the malignancy.