Effect of increased sample input on the LLOD of the UCP-LF CAA assay. AWA-TCA standard series in urine (CAA concentration indicated in upper panel), analysed in triplicate with the UCP-LF wet assay format. Spiked urine was extracted with 1 volume 4% (v/v) TCA, the resulting TCA-supernatant was either tested directly with the UCAA10 assay or first concentrated using 0.5, 4, and 15 mL Amicon centrifugal filter devices. Arrows in the lower panel (a blow up of the y-axis) indicate the QC cutoff threshold for the different assays; left to right: UCAA10, −250, −2000 and −7500. Error bars indicate 1 standard deviation (n = 3).