Table 3.
Reference mass fraction values (μg/kg) for selected phenol metabolites in SRM 3672 organic contaminants in smokers’ urine and SRM 3673 organic contaminants in non-smokers’ urine
| SRM 3672 | SRM 3673 | |
|---|---|---|
| Bisphenol A(a,b) | 3.05±0.16(c) | 1.96±0.11(c) |
| 2,5-Dichlorophenol(b) | 1.77±0.06(d) | 0.687±0.046(d) |
| Benzophenone-3(b) | 191±5(d) | 274±7(d) |
| Methyl Paraben(b) | 113±2(d) | 79.5±2.1(d) |
| Ethyl Paraben(b) | 8.12±0.20(d) | 10.3±0.3(d) |
| Propyl Paraben(b) | 17.6±0.3(d) | 21.6±0. 6(d) |
| Butyl Paraben(b) | 11.1±0.2(d) | 1.11±0.03(d) |
| Triclosan(b) | 17.7±0.5(d) | 6.27±0.32(d) |
NIST analysis GC/MS
CDC analysis; data were converted from ng/mL to μg/kg using the density of the urine (1.019 g/mL)
The reference value is a weighted mean of average mass fractions, with one average from each of two analytical methods [30, 31]. The expanded uncertainty is the half-width of a symmetric 95 % parametric bootstrap confidence interval [32], which is consistent with the ISO Guide [33, 34]. The effective coverage factor, k, is 2
The reference mass fraction value is the mean of results obtained using one analytical technique. The expanded uncertainty, U, is calculated as U = kuc, where uc is one standard deviation of the analyte mean, and the coverage factor, k, is determined from the Student’s t-distribution corresponding to the associated degrees of freedom and a 95 % confidence level for each analyte. The effective coverage factor, k, is 2.20