Determination of Phosphonylated Tyrosine as a Marker of Exposure to Nerve Agents in Dried Blood Plasma Spots by HPLC–HRMS/MS

Abstract

A procedure for the determination of phosphonylated tyrosine, a marker of exposure to organophosphorus nerve agents, in dried blood plasma spot (DBS) samples by means of liquid chromatography/tandem high-resolution mass spectrometry was developed. The DBS samples on Protein Saver 903 Card substrates were shown to be stable for two months on storage at 22 and 40°C. It was found that the temperature of storage has a high impact on the stability of the DBS samples: the analyte concentration in the samples stored at 40°C was about three times lower than that in the samples stored at room temperature. It was shown that the special Protein Saver 903 Card substrates could be replaced by an ordinary blue ribbon filter paper. In the latter case, the tyrosine adducts of nerve agents were reliably determined in the DBS samples stored for a month at room temperature (22°C). However, for storage at elevated temperatures (40°C), the use of filter paper substrates is not recommended. The proposed approach to storage of blood samples allows one to take and easily transport large series of samples and automate their analysis.