“…The precision of the proposed method was evaluated by measuring intra-and inter-day relative standard deviations (RSDs) at concentrations 10.0 ng mL −1 for E1, E2, E3 and EE2, which were within the range of 3.2-3.8% and 4.0-5.3%, respectively. Some methods have been reported to determine estrogens [11,[32][33][34]. Compared with the other sample pretreatment methods (Table 4), this developed method is simple, timesaving, reliable, sensitive and good selectivity.…”