Hello Kristen Navarro

The optimal wavelength for absorbance in MTT assay is 570 nm. If a 570 nm filter is not available, absorbances may be read with any filter in the wavelength range of 550-600 nm. Sometimes, in MTT assay the absorbance is read at two different wavelengths namely, 570nm and a reference wavelength of 630nm. 630 nm is a wavelength where MTT has minimal absorption. Absorbance variations at this wavelength are exclusively attributable to the presence of background that could interfere with the reading of the absorbance at 570 nm. So, the absorbance at 630nm is subtracted from the absorbance detected at 570nm.

However, I feel the absorbance at 630nm is not required because the background noise measured at 630nm is present in all the wells.

So, you may go ahead and buy any commercial MTT kit and record the absorbance at 550nm which the machine can read even if the kit recommends 570nm. It will not make much of a difference.

Best.