Question

what is fluorescence intensity of 25.00 ml aliquot of 40ppm quinine solution at 450 nm, if flouresence intensity of another 25.00 ml aliquot of quinine solution mixed with 10.0ml of 50 ppm standard quinine was 339

Answer 1

Intensity = concentration x constant

where 10 ml of 50ppm added to 25 ml of 40 ppm , we get 35 ml solution of 42.857 ppm

( since M final after mixing = M1V1+ M2V2 / ( V1+v2)   = ( 50x10 ) + ( 40x25) / ( 10+25)   = 42.857 ppm)

we find the value of constat

339 = (42.857 ppm /35ml)   x Constant

constant = 276.85 ml/ppm

now we use this value and concentration value of 40ppm/25ml t find new flouroscence intesity

Intensity = ( 40ppm/25ml) x ( 276.85 ml/ppm)

= 443