Table B2: Caffeine concentrations in coffee products reported in the scientific literature.,,,,,

Reference,Quantity of coffee,Volume of water (ml),Caffeine level as  reported,Caffeine level converted to mg/l ,Caffeine concentration adjusted for weight and volume used (mg/l)a
Instant,,,,,
Bunker and McWilliams4,1.9 g,150,61-70 mg/150 ml,407-467,257-295
Reid and Good5,1.9 g,200,43.0 mg/200 ml,215,181
Blauch and Tarka6,0.5 g,125,46.7-67.6 mg/cup,311-45b,197-285b
Scott et al.9,1 tsp (1.6 g),200,56.9-74.7 mg/200 ml,285-374,285-374
Stavric et al.11,1 g,100,212-427 µg/ml,212-427,170-342
Stavric et al.11,consumer prepared,,83.5-479.5 µg/ml,84-480 ,NA
Filter/percolated,,,,,
Bunker and McWilliams4,variable methods,,93-153 mg/150 ml,620-1020,NA
Reid and Good5,5 g,200,63 mg/200 ml,315,164
,10 g,200,118 mg/200 ml,590,153
Blauch and Tarka6,60 g,1020,93-163.5 mg/150 ml,620-1090,137-241
Scott et al.9,1 tsp (1.6 g),200,74-263 mg/200 ml,370-1315,601-2137
Stavric et al.11,probably 1 g and 100 ml,,130.20 µg/ml,130,169
Stavric et al.11,consumer prepared (drip and percolated),,156.7-740.7 µg/ml,157-741,NA
Bell et al.15,variable methods,,50-143 mg/177 ml,282-808,NA

Notes: ,,,,,
NA: Not applicable.,,,,,
tsp: teaspoon.,,,,,
aCaffeine concentration which would have been expected using the same coffee:water ratio as this survey (1.6 g of instant coffee or 2.6 g of filter/percolated coffee in 200 ml,,,,,
water).  This assumes that there is a linear relationship between the weight of coffee and the caffeine extracted,,,,,
bThis paper used 0.5 g of coffee in 125 ml but reported the caffeine concentrations which would be expected using 1.9 g (as used by Bunker and McWilliams4). ,,,,,
 Calculations here are based on the assumption of a 150 ml cup as used by Bunker & McWilliams4.,,,,,