Table 3. Mean δ13CCARBOXYL values for RMs run with pH 5.8 and pH 1.5 reagents.
| RM | mean | sd | |||||
|---|---|---|---|---|---|---|---|
| pH 5.8 | |||||||
| date | Mar-17 | Jan-18 | Mar-18 | ||||
| Val (V3) a | +31.60 | +31.79 | +31.56 | +31.68 | ± 0.16 | ||
| Gly (G3) a | +14.70 | +14.87 | +14.66 | +14.76 | ± 0.15 | ||
| Gly (WH) a | -27.00 | -26.82 | -27.09 | -26.96 | ± 0.19 | ||
| Ala (TTA) a | -31.58 | -31.28 | -31.48 | -31.38 | ± 0.14 | ||
| pH 1.5 | |||||||
| date | Jan-18 | Mar-18 | Jul-18 | ||||
| Val (V3) a | +31.74 | +31.75 | +31.43 | +31.64 | ± 0.18 | ||
| Gly (G3) a | +14.22 | +14.13 | +13.77 | +14.04 | ± 0.24 | ||
| Gly (WH) a | -28.05 | -27.91 | -28.24 | -28.07 | ± 0.16 | ||
| Ala (TTA) a | -31.56 | -31.81 | -31.51 | -31.63 | ± 0.16 | ||
All data were normalized to δ13CCARBOXYL USGS40 = -30‰.
a these RMs were used in the previous validation of the PSIA method [9].