Quantitative colorimetric assay. This assay has high sensitivity and excellent specificity for detection of sheep E2. No significant cross-reactivity or interference between sheep E2 and analogs was observed. Note: Limited by current skills and knowledge, it is impossible for us to complete the cross-reactivity detection between sheep E2 and all the analogs, therefore, cross reaction may still exist. Sample types: plasma, serum, tissue homogenates. Range: 0.4 - 30 ng/ml. Precision: Intra-assay: CV%<15% Inter-assay: CV%<15%.