Table 2.
Reference mass fraction values (μg/kg) for selected phthalate metabolites in SRM 3672 organic contaminants in smokers’ urine and SRM 3673 organic contaminants in non-smokers’ urine
| SRM 3672(a,b) | SRM 3673 (a,b) | |
|---|---|---|
| Mono-carboxynonyl phthalate isomers(c) | 1.92±0.06 | 1.49±0.02 |
| Mono-carboxyoctyl phthalate isomers(d) | 21.3±1.1 | 10.5±0.5 |
| Mono-(2-ethyl-5-carboxypentyl) phthalate | 35.2±1.7 | 30.1±1.0 |
| Mono-(2-ethyl-5-hydroxyhexyl) phthalate | 24.8±0.4 | 22.3±0.3 |
| Mono-(2-ethyl-5-oxohexyl) phthalate | 14.9±0.4 | 12.2±0.2 |
| Mono-(2-ethylhexyl) phthalate | 4.13±0.15 | 4.34±0.16 |
| Mono-(3-carboxypropyl) phthalate | 2.99±0.20 | 1.91±0.21 |
| Monobenzyl phthalate | 8.37±0.18 | 5.69±0.17 |
| Monoethyl phthalate | 94.5±3.08 | 0.2±2.1 |
| Mono-isobutyl phthalate | 6.40±0.28 | 5.18±0.26 |
| Mono-n-butyl phthalate | 10.6±0.5 | 11.2±0.7 |
CDC analysis; data were converted from ng/mL to μg/kg using the density of the urine (1.019 g/mL)
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
Mono-(2,7-dimethyl-7-carboxyheptyl) phthalate was used as the calibrant for the quantification of the mono-carboxynonyl phthalate isomers
Mono-(2,6-dimethyl-6-carboxyhexyl) phthalate was used as the calibrant for the quantification of the mono-carboxyoctyl phthalate isomers