## 3 Results  
The average content of tannins expressed as pyrogallol in Central European raw material (_C. quercusfolii_), depending on the habitat type of forest, ranged from 11.86% to 14.50% for the moist mixed broadleaved forest, from 12.95% to 15.11% for fresh broadleaved forest and from 14.01% to 15.95% for a moist broadleaved forest (Table 2). Statistically significant differences between the mean values of tannin content between all the different habitat types of the forest were shown (Figure 1A). In turn, for _A. infectorius_ gall nuts, the tannin content ranged from 34.39% to 35.21% for the first harvest and from 38.70% to 41.09% for the second harvest (Table 3). In this case, the analysis also confirmed statistically significant differences (Figure 1B). \begin{table}
\begin{tabular}{c c} \hline
**Parameter** & **Characteristics** \\ \hline \multirow{4}{*}{Type, manufacturer} & Stationary Phase \\  & Poroshell 120 EC-C18 (Agilent Technologies, Santa Clara, CA, USA), 4.6 \(\times\) 150 mm, 2.7 \(\upmu\)m \\ \multirow{2}{*}{Column temperature} & T = 25 \({}^{\circ}\)C \\ \hline \multirow{4}{*}{Phase composition} & Mobile Phase \\  & A: water, 5 mM ammonium formate in water (99.9\%), 0.1\% formic acid (0.1\%) \\ \multirow{2}{*}{Phase composition} & B: methanol, 5 mM ammonium formate in methanol (99.9\%), formic acid (0.1\%) \\ \multirow{2}{*}{Flow rate} & V\({}_{\text{flow}}\) = 0.5 mL/min \\  & 0 min–80\% A, 20\% B \\ \multirow{2}{*}{Gradient Elution Profile} & 0.1–10 min–50\% A, 50\% B \\  & 10.1–14 min–10\% A, 90\% B \\ \multirow{2}{*}{Gradient Elution Profile} & 14.1–20 min–80\% A, 20\% B \\ \hline \multirow{4}{*}{Detector with a photodiode array (DAD) 276; 8 nm, Ref. 360, 100 nm} \\ \cline{1-1}  & Mass spectrometer detector (MS): electrospray (ESI), ionization mode: [M-H]\({}^{-}\), fragmentor 135, \\ \cline{1-1}  & carrier gas flow rate 5 L/min, carrier gas flow temperature 350 \({}^{\circ}\)C, voltage on the capillary 3500 V, \\ \cline{1-1}  & mass range 50–2000 (\(m/z\)) \\ \cline{1-1} \cline{2-2} Analysis time & 20 min \\ \cline{1-1} \cline{2-2} Sample injection volume & 5 \(\upmu\)L \\ \hline \end{tabular}
\end{table} 
Table 1: Characteristics of parameters for the determination of tannin compounds by means of the HPLC-DAD-MS technique. Tannins are natural plant substances with a high molecular weight, from 300-5000 Da. Profiling of the content of tannic acid, considered to be the most important active ingredient of oak galls, is determined by examining the content and proportion/ratio of gallotannins [32; 33; 34; 35]. Initially, a direct injection of aqueous extracts of gall nuts and gallic and tannic acid standards (GA and TA) was made to the mass spectrometer in order to check the ion mass distribution in the tested samples. Figure 2 shows the result of this analysis. The distribution and quality profile of the masses in _A. infectorius_ gall nuts largely coincides with the masses characterizing the mixture of standards (gallic and tannic acid), the same values (\(m/z\)) of ions obtained in the SCAN mode [M-H]\({}^{-}\) appear, e.g., 169, 247, 321, 939, 1091, 1396, which proves that these gall nuts contain compounds in the same ionic form as in the gallic and tannic acid standards (Figure 2A).