A sensitive, robust and high-throughput isotope dilution LC–MS/MS method for quantifying three folate forms in serum: Supplementary data

This study aimed to establish an isotope dilution LC–MS/MS method for the determination of folic acid,
5-formyltetrahydrofolate and 5-methyltetrahydrofolate in human serum. This method was then used to
quantify these three folate forms in the healthy adult population and supplement users. A stable 96-
well solid-phase extraction system was used to prepare serum samples. The highly sensitive method was
established using a Shimadzu LCMS-8060NX. The linearity was good in the range of 0.1–10 nmol/l for
folic acid and 5-formyltetrahydrofolate and 1.0–100 nmol/l for 5-methyltetrahydrofolate. The accuracy
and precision were good. The method was sensitive, robust and high-throughput and could be used for
the routine clinical monitoring of these three folate forms in the Chinese population.