You certainly wanna ask the lab to do the analyze, they do it cheaper and by far more accurate:
to measure alpha or bitter acids spectral photometrical you have to extract the bitter substances out of your acidified sample, remove disturbing factors by washing the archieved extract with acidified methanol and measure the concentration of the alpha acid in alcalinic methanol at 255 and 360 nm. the frequence on a spectral photometer is normaly always adjustable. i guess you get the idea that the lab is the better choice although you could use the photometer for so much more..
"How much beer is in German intelligence !" - Friedrich Nietzsche