SERS signal of human blood plasma
To achieve reliable SERS detection of drugs in blood plasma, we studied the influence of anticoagulant used to stabilize the blood, as well as pH value and sample dilution on background SERS signal of plasma. SERS signal of bilirubin is dominant in acidic medium regardless of the used anticoagulant and the level of plasma dilution. The background signal of plasma in neutral and alkaline media is associated with the signal of the anticoagulant used. The analysis of spectra of ceftriaxone spiked plasma showed that the SERS bands of the antibiotic can be detected only in alkaline and neutral media, and dilution leads to signal increasing due to the decrease of concentration of plasma components and reduction of their competition with the analyte to the SERS-active surface. The optimal anticoagulant (sodium citrate) for SERS analysis was determined because it demonstrates minimal/moderate effect on the analytical signal that allows development of more universal analysis protocols.
The work was supported by Russian Science Foundation (project 18-13-00081).
Natalia E. Markina
Saratov State University
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