Table B1: Caffeine concentrations in tea products reported in the scientific literature.,,,,,,,

Reference,Quantity of tea,Volume of water (ml),Brewing time (mins),Caffeine level as  reported,Caffeine (mg/g tea),Caffeine level converted to mg/l ,Caffeine concentration adjusted for weight and volume used (mg/l)a
Tea bagsb,,,,,,,
Bunker and McWilliams4,1 bag,150,1,21-33 mg/140 mlc,NA,150-236,NA
,1 bag,150,3,35-46 mg/140 ml,,250-329,
,1 bag,150,5,39-50 mg/140 ml,,279-357,
Blauch & Tarka6,1 bag,177,5,40.9-67.4 mg/6 oz,NA,231-381 ,NA
Scott et al.9,1 bag,200,5,42.8-68.8 mg/200 ml,NA,214-344 ,NA
Stavric et al.11,1 bag,175,2,215.28-249.36 µg/ml,NA,215-249,NA
,1 bag,175,5,399.48-407.40 µg/ml,,400-407,
Loose tea,,,,,,,
Bunker and McWilliams4,1 tsp (1.7 g),150,1,19 mg/140 mlc,11.1,136,89
,1 tsp (1.7 g),150,3,25 mg/140 ml,14.7,179,118
,1 tsp (1.7 g),150,5,28 mg/140 ml,16.5,200,132
,1 tsp (3 g),150,1,31 mg/140 ml,10.3,221,83
,1 tsp (3 g),150,3,38 mg/140 ml,12.7,271,101
,1 tsp (3 g),150,5,40 mg/140 ml,13.3,286,100
Galasko et al.8,2.563 g,175,1-2,5.71-9.29 mg/fl oz,13.7-22.3,201-327,110-179
,2.563 g,175,20,11.59-12.39 mg/fl oz,27.9-29.8,408-436,223-238
Scott et al.9,1 tsp ,200,5,51.6-63.2 mg/200 ml,NA,258-316 ,NA
Stavric et al.11,1 g1 g,44 44 ,25,123.8-230.1 mg/l,5.4-10.1,124-230,44-81
,,,,204.4-340.7 mg/l,9.0-15.0,204-341,72-120
Instant teas,,,,,,,
Reid and Good5,1.00 g,200,NA,29 mg/200 ml,NA,145,72.5
Blauch and Tarka6,0.57 g,177,NA,32.4-35.0 mg/6 oz,NA,183-198,142-154

Notes:,,,,,,,
NA: Not applicable.,,,,,,,
tsp: teaspoon.,,,,,,,
aCaffeine concentration which would have been expected using the same tea:water ratio as this survey (1.6 g of loose tea or 0.5 g instant tea in 200 ml water).  ,,,,,,,
This assumes that there is a linear relationship between the weight of tea and the caffeine extracted.
bWeight of tea bags not known.
cUsed 150 ml water but the results were reported in mg/140 ml.