Wrong Instrument Settings for Detection Wavelength (ELISA (Signal Problems))

Question

Accepted Answer

No signal or very low signal readings from plate reader despite visible color development or expected fluorescence. Signal does not correlate with visual observations. Common causes: 1) Plate reader absorbance wavelength does not match substrate (e.g., TMB requires 450 nm, OPD requires 490 nm) 2) Excitation/emission filters are incorrect for the fluorophore used 3) Detection mode is set to wrong method (e.g., endpoint instead of kinetic) 4) Reference wavelength setting interferes with signal measurement Solutions: 1) Verify correct absorbance wavelength: TMB at 450 nm, ABTS at 405 nm, OPD at 490 nm 2) Confirm fluorescence excitation/emission match fluorophore specifications exactly 3) Use kinetic reading mode for slow-developing colorimetric reactions to capture signal development over time 4) Check reference wavelength is appropriate (typically 540-650 nm for colorimetric assays)