Table 6.

Recovery of unconjugated estrogens after extraction, derivatization and analysis (n=5).

Analytes	LQC (1.5 pg/mL)				MQC (75 pg/mL)				HQC (175 pg/mL)
	Post- spike	Pre- spike	Recov. (%)	SD	Post- spiked	Pre- spiked	Recov. (%)	SD	Post- spiked	Pre- spiked	Recov. (%)	SD
E2	1.62	1.37	84%	4.0	80.16	78.46	98%	1.1	184.23	173.24	94%	4.9
16α-OH-E2	1.45	1.53	106%	13.9	86.31	78.98	92%	2.1	173.03	174.07	101%	4.7
4-MeO-E2	1.44	1.57	109%	11.4	78.73	81.77	104%	3.0	186.73	185.67	99%	5.8
2-MeO-E2	1.66	1.85	112%	5.4	78.87	78.96	100%	2.8	177.55	1 73.65	98%	4.3
4-OH-E2	1.43	1.56	109%	8.6	77.98	77.54	99%	3.1	182.29	172.42	95%	4.0
2-OH-E2	1.42	1.43	100%	18.9	78.71	76.30	97%	1.9	184.42	166.04	90%	4.4

Post-spike: Internal standard spiked into MTBE extracted human serum, followed by derivatization.

Pre- spike: Internal standard spiked into human serum, followed by MTBE extraction and derivatization.

Recov.(%)= [(pre-spike-post-spike)/post-spike]×100