1) Selecting a 430nm LED

There are several 430nm through-hole LEDs available, although surface mount LEDs are scarcer. We initially tested two LEDs:

  1. SloanLED: Allied Electronics Part # 70015942Manufacturer - SloanLED, part # SL905BCE
  2. CMD LED: Digikey Part # CMD383UBC/H2. Manufacturer - Chicago Miniature Lighting, part # CMD383UBC/H2 
Initial testing was carried out by comparing the absorbance of different beers with the two LEDs. We initially just soldered the LEDs onto spare colorimeter LED boards. In these inital tests, absorbance at 430nm was highest with the 430nm LED from SloanLED, so all future measurements have been carried out with this LED.  

Victory Prima Pils0.39050.3875
Mongo IPA0.64650.6235
Two brothers1.0450.996
Alaskan raspberry wheat ale1.07451.026
Strand Atticus1.41751.2985
Alesmith nut brown ale1.35851.27
Craftsman Edgar Ale1.6761.5545