Highly sensitive detection of clenbuterol in urine sample by using surface plasmon resonance immunosensor

This study proposed the filtration method for removal of inhibitors from real urine samples for immunoassay without centrifuge. Although the inhibitors could not be removed by the physical filtration, the carboxyl group terminated silica effectively removed the inhibitors. In a low pH, antibody formed aggregation due to the protonation. We propose to adjust pH of the sample solution by adding a phosphate buffer solution (pH 7.5). As a result of pretreatment, the SPR immunosensing achieved the SPR signal of 45 mdeg and a low limit of detection with 100 ppq (100 fg mL−1).