Tell me more about these solvents, because I might have access to a spectrometer due to my occupation as a biology student.
Got a method?
Alpha and Beta Acids in Hops
(reference: ASBC MoA. 8th edition, 1992)
Method
1. Place 5.000 +/- .001 gr pulverized hops in an extraction bottle and add 100 mL toluene.
2. Shake for 30 min with vigorous agitation.
3. Let stand until clear or centrifuge (preferred).
4. Dilution A: Dilute 5.0 ml of this extract to 100 mL with methanol.
5. Dilution B: Dilute an aliquot of the dilution A with alkaline methanol (0.2 mL 6M NaOH per 100 mL MeOH) so that the Abs at 325 and 355 falls within the most accurate range of the instrument (usually between 0.1 and 1)
6. Immediately read dilution B (1 cm) at 275, 325 and 355 vs a toluene blank that was prepared and diluted in EXACTLY the same manner.
Notes:
? Hexane may be substituted for toluene
Calculations:
Dilution factor, d= (volume dil A x volume dil B)/ (500 x aliq extract A x aliq dil A)
% alpha acids= d x (-51.56 A355+ 73.79 A325-19.07 A275)
% beta acids= d x (55.57 A355-47.59 A325 + 5.10 A275)
Example:
1. 5 gr hops extracted with 10 mL toluene
2. 5 mL clear extract diluted to 100 mL with methanol=Dilution A
3. 3 mL Dilution A diluted to 50 mL with alkaline methanol
4. Absorbances
o A355=0.615
o A325= 0.596
o A275=0.132
d = (100 x 50) / (500 x 5 x 3) = 0.667
alpha = 0.667 x [ -(51.56 x 0.615) + (73.79 x 0.596) - (19.07 x 0.132) = 6.5
beta = 0.667 x [ (55.57 x 0.615) - (47.59 x 0.596) + (5.10 x 0.132) = 4.3
