## 3 Results and Discussion  
### Method Evaluation  
In this study, the focus has been given on validation data (Supplementary Tables S1 and S2) at least from one matrix along with proficiency test (PT) results evaluated in accordance with ISO 17,043 standard (Tables 1-6) to emphasize the actually successful introduction of the standard method. The presented matrix is the olive oil sample as it was one of the most complex matrices validated and for which PT results could be shown. The screening validation was performed later than the confirmatory validation. The screening validation was carried out with 425 compounds from which 415 compounds could be detected at or below 0.050 mg/kg (Supplementary Table S1). The aim of screening validation was to establish the detection capability of the standard method using our instrument setup. The SDL levels in olive oil are detailed in Supplementary Table S1 and varied between 0.005 to 0.05 mg/kg. \begin{table}
\begin{tabular}{c c c c} \hline
**Component** & **Assigned Value (\(\mu\)g/kg)** & **Result (\(\mu\)g/kg)** & **z-Score** \\ \hline Benalaxyl & 68.8 & 71.5 & 0.2 \\ \hline Boscalid & 96.1 & 88.9 & \(-\)0.3 \\ \hline Diazinon & 19.5 & 20.3 & 0.2 \\ \hline Metolachlor (sum of constituent isomers including S-metolachlor) & 91.2 & 94.8 & 0.2 \\ \hline \end{tabular}
\end{table} 
Table 1: Blueberry purée, proficiency test 19,258 (FAPAS), October 2018. \begin{table}
\begin{tabular}{c c c c} \hline
**Component** & **Assigned Value (\(\mu\)g/kg)** & **Result (\(\mu\)g/kg)** & **z-Score** \\ \hline Duprofezin & 42.8 & 53.0 & 1.1 \\ Dimetheto & 152 & 166 & 0.4 \\ Heeythiazole & 54.6 & 63.0 & 0.7 \\ Methamidophos & 71.8 & 84.0 & 0.8 \\ Methomyl & 64.5 & 64.0 & 0.0 \\ Phenthoate & 87.2 & 98.0 & 0.6 \\ Pyrimethanil & 109 & 128 & 0.8 \\ Quinalphos & 72.8 & 84.0 & 0.7 \\ Tebuconazole & 137 & 162 & 0.8 \\ \hline \end{tabular}
\end{table} 
Table 2: Olive oil, proficiency test 5147 (FAPAS), October 2020. \begin{table}
\begin{tabular}{c c c c} \hline
**Component** & **Assigned Value (\(\mu\)g/kg)** & **Result (\(\mu\)g/kg)** & **z-Score** \\ \hline Dinotefuran & 76.2 & 83.1 & 0.4 \\ Kresoxim-methyl & 36.2 & 53.4 & 2.2 \\ Omethoate & 117 & 143 & 1.0 \\ Pendimethalin & 41.1 & 58.6 & 1.9 \\ Proquinazid & 82.7 & 101 & 1.0 \\ Tebufenpyrad & 59.1 & 74.9 & 1.2 \\ Thiacloprid & 75.9 & 80.1 & 0.3 \\ \hline \end{tabular}
\end{table} 
Table 3: Apple purée, proficiency test 19,307 (FAPAS), March 2021. In accordance with SANTE/11312/2021 [19], recovery and precision were calculated for 10% of the analyzed compounds (Supplementary Table S2) under confirmatory validation. Linearity was evaluated by the regression coefficient of the six-points matrix-matched calibration curve (R\({}^{2}\) > 0.9950). All results met the following performance criteria during validation: precision, <20 RSD%; recovery, 70-110%. The participation in several PTs is also part of the method evaluation. The PT results are detailed in Tables 1-5. The PT is satisfactory if the z-score calculated for a compound is between \(-\)2 and 2. So far, only two compounds were out of this range, namely kresoxim-methyl and boscalid. These were evaluated as questionable. Ruling Out the False Identification of Atrazine-Desethyl in a Date Seed Coffee (Coffea Phoenix dactylifera) Sample with the Help of IR  
A date seed coffee sample was screened for 480 pesticides including atrazine-desethyl, the metabolite of atrazine. Unlike atrazine, atrazine-desethyl has no MRL or default MRL (0.01 mg/kg) in food, but our laboratory routinely analyses this compound in water [24], so the screening method contains the ion transition of atrazine-desethyl as well. In the \begin{table}
\begin{tabular}{c c c c} \hline
**Component** & **Assigned Value (\(\mu\)g/kg)** & **Result (\(\mu\)g/kg)** & **z-Score** \\ \hline Malathion & 58.0 & 49.1 & \(-\)0.7 \\ Phosmet & 51.3 & 52.6 & 0.1 \\ Prochloraz & 58.2 & 63.7 & 0.4 \\ Proporcur & 78.0 & 71.0 & \(-\)0.4 \\ Tetraconazole & 76.0 & 70.8 & \(-\)0.3 \\ \hline \end{tabular}
\end{table}