Figure 5: The effect of urine on antibody response. (a) SPR sensorgrams showing sensor responses for 2 μg/mL of anti-TTX in SAB at pH 4.5 with 10% urine or 10% water. (b) Calibration curves showing normalized wavelength shift versus concentration of TTX in sample for one set of data normalized to either reference antibody response with 10% urine or 10% water. The reference antibody response in urine was ~25% higher than in buffer without urine. A 1 nm SPR wavelength shift at 750 nm to 751 nm represents a protein surface coverage of ~161 pg/mm2.