Determination of contaminants of emerging concern in raw pig manure as a whole: difference with the analysis of solid and liquid phases separately

The content of veterinary drugs in manure is usually estimated by the amount of residues determined in its solid or liquid phase, individually, which previously required a separation step. As an alternative, a multiresidue method for the analysis of 48 veterinary drugs and other contaminants of emerging concern (CECs) in swine raw manure as a whole has been developed and in-house validated in this work. The impact of several experimental factors during ultrasound assisted extraction was assessed. Hence, the use of alumina seemed to especially decrease the matrix effect and improve the overall recovery of drugs, mainly those with a high octanol-water partition coefficient. CECs in the extracts were analyzed by ultra-high performance liquid chromatography coupled to mass spectrometry in tandem. A standard addition-matrix matched calibration was used for quantification. Application of the method to two related samples (raw manure and farm centrifuged raw manure) from a facility revealed that the concentrations of CECs determined in the raw manure by the comprehensive methodology were higher than those calculated by adding the concentrations measured in the solid and liquid phases, separately. This was attributed to the loss of CECs adsorbed on fine particles in the suspension during the sample preparation procedure of the liquid-phase. Furthermore, the decrease of residues in the raw manure when this is centrifuged in the farm to yield compost is shown.