**3. Results**

#### *3.1. Quality Assurance*/*Quality Control (QA*/*QC)*

Based on analysis of working standard solutions in optimal conditions, calibration curves were prepared. Regression coefficients and selected validation parameters are presented in Table 2. The obtained results are satisfactory, showing that the proposed method is suitable for analysis of the selected pharmaceuticals. The recovery for standards were calculated based on peak areas. Recoveries ranged from 65% to 121%, for all pharmaceuticals (mean values for individual compounds: ASA-65%, AMP-81%, CAF-111%, CMZ-98%, CIP-102%, DIC-67%, ENR-111%, IB-92%, MTC-99%, MET-121%, NIM-102%, PAR-81%, PROP-115%, SA- 78%, SFC-75%, SPEC-71%, STREP-74%, SFC-82%, SDA-89% SGA-94% SMA-98%, SMZ-100%, SMX-106%, SNA-98%, STA-82%, TET-67%, TMP-79%). The recoveries of analytes were dependent on the matrix type. This suggests that the use of standard addition or analysis with labeled standards are necessary in order to improve the correction results.



*Molecules* **2020**, *25*, 1031

#### *3.2. Analysis of Real Samples*

Using the developed and validated method described above, a chromatographic analysis of extracts of real soil samples was performed. Each of the 15 samples was analyzed for the presence of 27 substances. Of these, 10 pharmaceuticals (MTC, SNA, SA, MET, SMZ, NIM, CBZ, TMP, PROP, PAR) and CAF were determined in soil samples collected in March (Figure 2a) and five pharmaceuticals (MTC, SA, SMZ, CBZ, SNA) in soil samples collected in July (Figure 2b). The largest number of various pharmaceuticals (MTC, TMP, SA, SMZ, PROP, CBZ) was determined at 7A\_M (the sample collected in March, location where the dirty litter was thrown away). None of the 27 pharmaceuticals sought was determined in sample 6A\_J. In reference samples (1B\_M, 1B\_J and 1C\_J) two of the pharmaceuticals (PAR, SNA) and CAF were determined, which were not found in the farm area. Moreover, none of the pharmaceuticals determined on the farm area were determined in reference samples. Therefore, farm area samples (area A) and reference location samples (area B and C) will be described separately, below.

**Figure 2.** *Cont*.

**Figure 2.** Concentration of detected pharmaceuticals and caffeine in soil samples (ng/g d.w); (**a**) 1–7A\_M, 1B\_M, soil samples, collected in area A (around poultry house) and area B (450 m away) in March (M); (**b**) 1–7A\_J, 1B\_J, 1C\_J soil samples, collected in area A (around poultry house) area B (450 m away) and area C (980 m away) in July (J). MTC—matoclopramide, MET—metoprolol, TMP—trimpetoprim, SA—salicic acid, NIM—nimesulide, SMZ—supfamethazine, PROP—propranolol, CBZ—carbamazepine, CAF—caffeine, SNA—sulfanilamide, PAR—paracetamol.
