Mr./Miss/Mrs Aghaei,

This depends on the type of your analyte.

Dear Ayuob,

In addition, you also need to consider some technical aspects such as band shape (i.e. band width) in order to select the best standard, Here find attached a useful paper about relevant technical aspects you must consider.

Best,

Arturo

Take care of scattering for larger particles and also for highly polydisperse samples

Thanks all, Ivanova. Kapusta, Sánchez, Ravi Kishore V.

I used quinine sulfate and I acquire high QY 40%. At excitation wavelength 400nm, coumarin153 is appropriate standard but it haven't it.

Quinine sulphate is O.K. but you have to be careful because its QY is wavelength dependent.. SO experimental conditions have to be exactly those for which the QY was determined.

9,10-diphenylanthracene in cyclohexane may be another possibility (exc 365 nm, em between 400 and 450 nm  (QY 90%). One point deserves attention: re-absorption: if excitation and emission spectra overlap, you have to correct for this (i.e. you will get higher QY :))

For safe measurement it is wise to measure with 2 standards and then measure one standard against the other...