| 
   % Diff, versus nominal concentration (20 pmol/106 cells)
  | ara-GTP concentration (pmol/106 cells) |  
  |  | −30°C | −80°C |  
  |  | Day1 | Day3 | Day6 | Day6 | Day13 | 1 month | 2 months |  
  | MeOH / 28% ammonia water (7/3, v/v) |  
  | Mean | 18.08 | 19.65 | 14.60 | 18.05 | 20.24 | 19.12 | 17.57 |  
  | SD | 0.46 | 1.22 | 0.88 | 2.91 | 2.41 | 1.22 | 4.30 |  
  | CV% | 2.5 | 6.2 | 6.0 | 16.1 | 11.9 | 6.4 | 24.5 |  
  | % Diff | −9.6 | −1.7 | −27.0 | −9.8 | 1.2 | −4.4 | −12.2 |  
  | MeOH / 250 mM ammonium carbonate solution (7/3, v/v) |  
  | Mean | 17.00 | 13.01 | 12.06 | 14.81 | 13.56 | 9.65 | 11.00 |  
  | SD | 1.11 | 2.30 | 3.08 | 1.75 | 3.09 | 3.19 | 3.64 |  
  | CV% | 6.5 | 17.7 | 25.6 | 11.8 | 22.8 | 33.0 | 33.1 |  
  | % Diff | −15.0 | −35.0 | −39.7 | −25.9 | −51.7 | −45.0 |  |  |