A needle extraction utilizing a molecularly imprinted-sol–gel xerogel for on-line microextraction of the lung cancer biomarker bilirubin from plasma and urine samples

• A needle coated with molecularly imprinted polymer sol–gel coating was prepared.
• The needle extraction showed highly specific recognition for the bilirubin.
• Online application of needle trap for bilirubin using MEPS–LC/MS/MS was developed.
• The method validation showed that the method was accurate and robust.

In the present work, a needle trap utilizing a molecularly imprinted sol–gel xerogel was prepared for the on-line microextraction of bilirubin from plasma and urine samples. Each prepared needle could be used for approximately one hundred extractions before it was discarded. Imprinted and non-imprinted sol–gel xerogel were applied for the extraction of bilirubin from plasma and urine samples. The produced molecularly imprinted sol–gel xerogel polymer showed high binding capacity and fast adsorption/desorption kinetics for bilirubin in plasma and urine samples. The adsorption capacity of molecularly imprinted sol–gel xerogel polymer was approximately 60% higher than that of non-imprinted polymer. The effect of the conditioning, washing and elution solvents, pH, extraction time, adsorption capacity and imprinting factor were investigated. The limit of detection and the lower limit of quantification were set to 1.6 and 5 nmol L−1, respectively using plasma or urine samples. The standard calibration curves were obtained within the concentration range of 5–1000 nmol L−1 in both plasma and urine samples. The coefficients of determination values (R2) were ≥0.998 for all runs. The extraction recovery was approximately 80% for BR in the human plasma and urine samples.