On the low-resolution QQQ instrument, a median correlation coefficient (R 2 ) of 0.99 in both solvent and urine and a minimum R 2 of 0.95, supported by the lack-of-fit test (p < 0.05), indicated overall an excellent fit of the least square linear regression model in the calibration range. Moreover, the t-Student test proved the slopes to be significantly different from zero. In QQQ, the analytes were detected at one to two concentration levels lower than on the HRMS because the LOQ of the high-resolution instrument was typically higher and the same concentration levels were used for both experimental data sets (Table ). The orbitrap mass spectrometer had a slightly lower R 2 , although most compounds had a value >0.9, no significant lack of fit, and a slope different from zero suggesting a good fit of the linear regression model. In urine, the R2 was between 0.8 and 0.9 for several analytes (riddelliin-Noxide, 3-benzylidene camphor, β-ZEL-14-glucuronide, isoxanthohumol, nonylphenol, prochloraz). The lack-of-fit test indicated a poor fit to the model for β-ZEL-14-glucuronide, prochloraz and 3-benzylidene camphor. The retention time varied only slightly between the measurement on the high-resolution and low-resolution mass spectrometer. The difference in retention time was on average 11 s, which is very little given that two different LC systems with non-identical void volumes were employed. The highest discrepancy was observed for PFOS with 37 s and isobutylparaben with 30 s. The signal suppression/enhancement (SSE) ranged between 27% -208% with a value of 89% for the QQQ method (Table ). In the highresolution analyses, the SSE varied more severely (8% -264%), excluding analytes only detected in the standard with the highest concentration, the median was 97% (Table ). Drastic signal suppression was particularly evident for PFOS (8%), nonylphenol (20%), 4-octylphenol (22%) and methiocarb (24%) in HRMS. Signal enhancement was pronounced for ZEN-14-glucuronide (231%), ZEN-14-sulfate (264%), and 2-tert-butylphenol (190%). In the lowresolution measurements, 2-tert-butyphenol (204%), citrinin (191%), ZEN-14-sulfate (160%), PFOS (27%), OMC (33%), and HMF (38%) experienced high signal suppression/enhancement. In the high-resolution measurements, the SSE was generally more pronounced, although the overall trends were similar with both approaches.