## 3 Results and Discussion
### Validation of the Multi-Mycotoxin Determination Method in Vegetable Drinks
#### 3.1.5 Repeatability and Reproducibility  
Precision measures the degree of agreement between the analytical results obtained from a series of repeated measurements of the same analyte carried out under the conditions specified in the method. Precision reflects the random errors that occur when a method is used. The conditions under which precision was measured were under repeatability and reproducibility conditions. The repeatability of the conditions exists when the same analyst analyzes samples on the same day and with the same instrument or the same materials and in the same laboratory. Any change in these conditions (e.g., different analysts, different days, different instruments and different laboratories) implies that the conditions will be reproducible. Therefore, repeatability was measured with recovery studies in triplicate (n = 3) at three levels, including values corresponding to the maximum permitted limits and those close to the detection limit (L1, L2 and L3) with the four matrices. L1 was 0.5 \(\upmu\)g/mL (AFs OTA, AME, AOH and TENT), 1 \(\upmu\)g/mL (T-2), 0.25 \(\upmu\)g/mL (ENA, ENA1, ENB, ENB1 and BEA), 1.25 \(\upmu\)g/mL (ZEA, HT-2) and consecutive half values for L2 and L3. For reproducibility, the study was carried out on three different days (n = 9). Precision was measured in terms of the relative standard deviation of analytical results obtained with independently prepared control standards. Precision depends on the concentration and was measured with different concentrations within the working range, at high (L1), medium (L2) and low (L3) concentrations. Accuracy is acceptable when the lower concentration level is 20%. Precision was measured in terms of relative standard deviation of analytical results obtained with independently prepared control standards. The precision depends on the concentration and was measured with different concentrations within the working range at high (L1), medium (L2) and low (L3) concentrations. Accuracy is acceptable when  
Figure 3: Average matrix effect (**a**) and matrix effect (**b**) for each mycotoxin of each studied matrices.  
the lower concentration level is 20%. Precision was measured in terms of relative standard deviation of analytical results obtained with independently prepared control standards. Precision depends on the concentration and was measured with different concentrations within the working range at high (L1), medium (L2) and low (L3) concentrations. Accuracy is acceptable when the lower concentration level is 20%.  
The optimized method presented acceptable recovery values for both reproducibility, repeatability and precision, as shown in Figure 4a. Recovery mean values (intraday or repeatability and interday or reproducibility) were obtained for the three levels studied in the range from (49 \(\pm\) 18)% to (128 \(\pm\) 9)%, corresponding to T-2 and AME. Of the mycotoxins studied, higher recoveries were observed for EN A1 in the three levels (99% for L1, 113% for L2 and 99% for L3) and AME for L2 (116%) and L3 (128%) levels.  
In Figure 4b, the reproducibility results are shown for all mycotoxins at the L1 level for the four matrices, and the values observed have no significance differences between matrices.  
The repeatability results (n = 3) are shown in Figure 5 for the L1 level in the four matrices.