The majority of the 90 model analytes listed in Table were detected in the HRMS measurements with only 16, eight, and nine analytes not found at any spiked concentration in urine, serum, and plasma, respectively (reported as 'n.d.' in Table ). Several analytes had background contamination in the matrix matched blank, thus standard addition was applied. The analytes were 3methylcatechol, 4-hydroxybenzoic acid, enterolactone, and hippuric acid for urine; 3,3-hydroxyphenylpropanoic acid, hippuric acid, and salicylic acid for serum; and 3,3hydroxyphenylpropanoic acid, benzoic acid, hippuric acid, and salicylic acid for plasma.