2 / 7
2
Limit of Quantitation (LOQ):
46
The minimum analyte concentration for which quantitative results may be obtained with 95%
47
confidence.
48
49
Methyl xanthines
50
Caffeine; theobromine; and theophylline. Refer to table 4 for IUPAC nomenclature and CAS
51
registry numbers. See figure 2 for chemical structures.
52
53
Repeatability:
54
Variation arising when all efforts are made to keep conditions constant by using the same
55
instrument and operator, and repeating during a short time period. Expressed as the
56
repeatability standard deviation (SD
r
), or % repeatability relative standard deviation (%RSD
r
).
57
58
Reproducibility:
59
The standard deviation or relative standard deviation calculated from among-laboratory data.
60
Expressed as the reproducibility relative standard deviation (SD
R
) or %reproducibility relative
61
standard deviation (%RSD
R
).
62
63
Recovery:
64
The fraction or percentage of the analyte that is recovered when the test sample is analyzed
65
using the entire method.
66
67
Theaflavins
68
Theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin-3-3'-digallate. Refer to
69
table 6 for IUPAC nomenclature and CAS registry numbers. See figure 3 for chemical
70
structures.
71
72
Theanine
73
N-ethyl-L-glutamine; (2S)-2-ammonio-5-(ethylamino)-5-oxopentanoate. CAS registry
74
number: 3081-61-6. See figure 4 for chemical structure.
75
76
4.
Method Performance Requirements
:
77
Table 1: Analytical Ranges and LOQs
78
Component
catechins
methyl xanthenes
theaflavins
theanine
Analytical range (ppm)
10 – 500,000
10 – 500,000
10 – 100,000
10 – 100,000
LOQ (ppm)
5
79
Table 2: Method Performance Requirements by Range
80
Ranges (ppm)
10 – 50
51 - 500
501– 4,000
4,001 – 20,000
>20,000
Recovery (%)
80 -110
90-107
95-105
97-103
98-102
RSD
r
(%)
≤ 7
5
4
2
2
RSD
R
(%)
≤ 10
8
6
3
3
81
82
83
84