ortho-Nitrophenyl-β-galactoside (ONPG) is a colorimetric and spectrophotometric substrate for detection of β-galactosidase activity. This compound is normally colorless. However, if β-galactosidase is present, it hydrolyzes the ONPG molecule into galactose and ortho-nitrophenol. The latter compound has a yellow color that can be used to check for enzyme activity by means of a colorimetric assay (at 420nm wavelength). β-Galactosidase is required for lactose utilization, so the intensity of the color produced can be used as a measure of the enzymatic rate.

CAS：369-07-3
中文别名：邻硝基苯-β-D-吡喃半乳糖苷;2-硝基苯基-β-D-吡喃半乳糖苷(ONPG);2-硝基苯基-β-D-吡喃半乳糖苷;邻硝基苯基-β-D-吡喃半乳糖苷;邻硝基苯-β-D-半乳糖苷(ONPG);2-硝基苯基-b-D-半乳糖苷;2-硝基苯基β-D-吡喃半乳糖苷;2-氟代-2-去氧-D-葡萄糖;
英文别名：2-Nitrophenyl β-D-galactopyranoside;2-Nitrophenyl β-D-Galactopyranoside [Substrate;2-Nitrophenyl β-D-galactopyranoside (ONPG);2-Nitrophenyl beta-D-Galactopyranoside;2-Nitrophenyl-β-D-galactopyranoside;2-Nitrophenyl-β-D-Galactopyranoside;
分子式：C12H15NO8
分子量：301.249
精确质量：301.08
Psa：145.2
Logp：-0.7033

EINECS号：206-716-1

外观与性状：白色结晶固体
密度：1.599 g/cm3
沸点：572.4ºC at 760 mmHg
熔点：186-193°C (dec.)
闪点：300ºC
折射率：-68.8 ° (C=1, H2O)
稳定性：Stable under normal temperatures and pressures.
储存条件：2-8ºC
蒸汽压：6.1E-14mmHg at 25°C

安全说明：S22-S24/25
危险类别码：R36/37/38
WGK Germany：3
海关编码：29400090
危险品标志：Xi