Analytes Matrix Sample volume Sample preparation Preconcentration (x times) Assay –format LOD (ng/L) a) LOQ RSD (%) (at which concentration.) Cross reactivity Recovery (%) Levels (ng/L) ref E2 0.107 11.2% for E1) 1.7% for E3 <1% for EE2 and others nd-3.6 EE2 Surface water and STP-out 5 L Empore disc 5000 RIA 0.053 0.3% for E2 <0.1% for E1, E2 and others <0.01% for others 63-78 Nd-0.76 (65) Surface water 2-6 L 3333-10000 0.05 b) 91-108 (E2) 54-89 (EE2) 0.05-0.8 (E2) <0.05-0.07 (EE2) E2, EE2 STP-out 0.2-2 L Empore disc 333-3333 HPLC-cleanup ELISA 0.1 49-117 (E2) 51-110 (EE2) 0.2-4.1 (E2) <0.1-2.4 (EE2) (48) E2 STP-out 0.03 L C18 column 6 RIA ND 25% w E1 40-360 (39) E1, E2, EE2 Synthetic wastewater   c) c) c) TIRF 70-160 70-112 (116) E1, E2, EE2 Synthetic wastewater c) c) c) ETIA 10-850 52-109 (116) E2, E3 River water 0.02 d) d) TR-FIA 32 (E2) 5.5 (E3) <1.1 (E1, EE2, and others) 97-119 (51) E2 STP-out 0.02 Liquid-liquid exraction with diethyl ether 40 Electrochemical ELISA 0.125 3-5 <1% for E1 <0.3% for E2-17α <0.2% for testosterone and others 84-91 <2 (117) E2 ELRA