Table 2.
Validation data including calibration range, R2, SD of slopes and intercepts, recoveries (%), relative standard deviations expressed as a percentage (RSD%), degree of the matrix interference (MI%) for two levels such as 5 ng mL−1 and 50 ng mL−1, and method limits of quantification (mLOQ) for bisphenols in breast milk samples obtained after proposed QuEChERS-LC-QqQ-MS procedure.
| Analyte | Calibration Data | Recovery c (%) (RSD%) | MI% d | Recovery c (%) (RSD%) | MI% d | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Range (ng mL−1) | Calibration Curve | R 2 | SD of Slope a | SD of Intercept a | mLOQ b (ng mL−1) | 5 ng mL−1 | 5 ng mL−1 | 50 ng mL−1 | 50 ng mL−1 | |
| BPS | 1-50 | y = 3986x + 7542 | 0.9999 | 68 | 950 | 0.25 | 102 (8) | 12 | 95 (15) | 13 |
| BPF | 1-50 | y = 285x + 604 | 0.9998 | 13 | 180 | 0.13 | 68 (9) | 11 | 63 (9) | 10 |
| BPA | 1-50 | y = 203x + 547 | 0.9991 | 11 | 150 | 0.10 | 39 (7) | 10 | 35 (17) | 12 |
a SD of slope and intercept were obtained using the LINEST function (MS Excel 2010), which returns an array of the statistics for a calculated trend line by using the least squares method. b mLOQ = method limit of quantification. Minimal residue concentration at which elaborated procedure enabled identification and quantification of the analyte with acceptable reliability and accuracy. c Average recoveries (and RSD%) of the analytes in breast milk samples (n = 7, at each spiking level). d MI% = mean degree of the matrix interference expressed as percentage difference in a signal from the analyte in matrix (final extract) compared to the signal in injection solvent. MI% was studied for analyte concentrations corresponding to 100% recovery at investigated fortification levels in triplicates (n = 3).