LMWMs recovery was assessed using a dSPE-treated spiked urine and sham samples. The aim here was to create an artificial mixture resembling blood by spiking lipids and albumin into a matrix rich in LMWMs. A pooled urine sample, collected from six individual donors of mixed genders at multiple time points and free from investigated xenobiotics, was spiked with four concentrations of seven xenobiotics, three concentrations of 15 lipids and albumin. Details can be found in Experimental S6, Figure and Table . Spiked xenobiotic recoveries, and global small molecule recoveries were calculated by taking the quotient of the average intensity from six replicates measured in the dSPEtreated sample, against the average intensity measured in the corresponding sham treated sample.