Table 7.
Results for determinations of curcuminoids in turmeric and catechins in green tea in multiple QAP exercises.
| Curcuminoids | Target | DSQAP exercise M (n = 17–23) | DSQAP exercise O (n = 22–25) | |||
|---|---|---|---|---|---|---|
| SRM 3299 | SRM 3300 | SRM 3299 | SRM 3300 | SRM 3299 | SRM 3300 | |
| Bisdesmethoxycurcumin | 3.390 ± 0.054 | 18.25 ± 0.49 | 3.23 ± 0.66 (20) | 16.2 ± 5.5 (34) | 3.16 ± 0.16 (5.7) | 17.3 ± 0.58 (3.4) |
| Desmethoxycurcumin | 3.634 ± 0.64 | 117.1 ± 1.2 | 3.26 ± 0.54 (17) | 116 ± 13 (11) | 3.63 ± 0.13 (3.6) | 117 ± 2.2 (1.9) |
| Curcumin | 11.17 ± 0.21 | 822 ± 11 | 11.6 ± 2.1 (18) | 801 ± 123 (15) | 11.20 ± 0.43 (3.8) | 822 ± 22 (2.7) |
| Catechins | Target | DSQAP exercise I (n = 17–28) | HAMQAP exercise 5 (n = 6–12) | |||
| SRM 3255 | ||||||
| Catechin | 8.88 ± 0.90 | 9.84 ± 2.37 (24) | 7.95 ± 0.88 (11) | |||
| Epicatechin | 45.8 ± 6.5 | 43.2 ± 5.8 (13) | 38.3 ± 2.1 (5.5) | |||
| Epicatechin gallate | 97.2 ± 7.6 | 95.1 ± 13.4 (14) | 94.9 ± 3.5 (3.7) | |||
| Epigallocatechin | 79.2 ± 6.3 | 62.9 ± 34.8 (55) | 82.4 ± 6.6 (8.0) | |||
| Epigallocatechin gallate | 409 ± 18 | 408 ± 39 (10) | 406 ± 2.5 (0.6) | |||
| Gallocatechin | 21.3 ± 1.6 | 28.0 ± 20.2 (72) | 19.8 ± 1.9 (9.6) | |||
| Gallocatechin gallate | 37.8 ± 1.9 | 43.1 ± 10.6 (25) | 42.8 ± 1.5 (3.5) | |||
Target (NIST-assigned) values and participant consensus (QAP exercise) values are listed for distributed SRMs. The range for the number of labs which reported data for individual analytes is noted (n); the uncertainty for each result is the standard deviation; the percent RSDs of the consensus values for each analyte are indicated in parentheses.