Table 4.
Results of sample pre-treatment experiments on various types of sample matrices.
| Sample | Type of sample | sample mass [mg] | Amount of Cr in sample [μg] | fraction Cr3+ | Mass fraction of Cr-Cl species | Recovery of Cr [%] |
|---|---|---|---|---|---|---|
| DiluteHNO3/H2O2 pre-treatmenta | ||||||
| N-1A-#8 | Hibonite-rich Ca-Al-rich inclusion (CAI) | 0.20 | 0.22 | 0.994 | 0.006 | 99.4% |
| Y-#1 | Hibonite-rich Ca-Al-rich inclusion (CAI) | 0.03 | 0.12 | 0.992 | 0.008 | 99.2% |
| 22E | Fine-grained Ca-Al-rich inclusion (CAI) | 0.19 | 0.34 | 0.997 | 0.003 | 99.7% |
| N-53 | Melilite-rich type B/C Ca-Al-rich inclusion (CAI) | 1.70 | 1.29 | 0.998 | 0.002 | 99.8% |
| KT-1 | Melilite-rich FUN Ca-Al-rich inclusion (CAI) | 0.21 | 0.27 | 0.996 | 0.004 | 99.6% |
| NWA 7686 | Ureilite | 1.20 | 6.18 | 0.998 | 0.002 | 99.8% |
| NWA 6043 | CR carbonaceous chondrite | 2.00 | 7.10 | 0.995 | 0.005 | 99.5% |
| NWA 5958 | Ung. carbonaceous chondrite | 2.00 | 7.00 | 0.990 | 0.010 | 99.0% |
| Allende | CV carbonaceous chondrite | 1.65 | 5.83 | 0.994 | 0.006 | 99.4% |
| Alfianello | L ordinary chondrite | 2.50 | 9.16 | 0.981 | 0.019 | 98.1% |
| CPI Cr | CPI International pure Cr standard | 0.01 | 10.00 | 0.983 | 0.017 | 98.3% |
| DTS-2b | Dunite, USGS standard | 5.00 | 77.50 | 0.983 | 0.017 | 98.3% |
| DTS-2b | Dunite, USGS standard | 0.10 | 1.55 | 0.988 | 0.012 | 98.8% |
| Bir-1a | Basalt, USGS standard | 5.00 | 1.85 | 0.887 | 0.113 | 88.7% |
| Bir-1ac | Basalt, USGS standard (purified for Fe) | 5.00 | 1.85 | 0.996 | 0.004 | 99.6% |
| Bir-1a | Basalt, USGS standard | 0.10 | 0.04 | 0.941 | 0.059 | 94.1% |
| Bir-1ac | Basalt, USGS standard (purified for Fe) | 0.10 | 0.04 | 0.890 | 0.109 | 89.1% |
| DNC-1a | Dolerite, USGS standard | 5.00 | 1.35 | 0.928 | 0.072 | 92.8% |
| DNC-1ac | Dolerite, USGS standard (purified for Fe) | 5.00 | 1.35 | 0.970 | 0.030 | 97.0% |
| DNC-1a | Dolerite, USGS standard | 0.10 | 0.03 | 0.921 | 0.079 | 92.1% |
| DNC-1ac | Dolerite, USGS standard (purified for Fe) | 0.10 | 0.03 | 0.912 | 0.088 | 91.2% |
| Concentrated hot HCl pre-treatmentb | ||||||
| Bir-1a | Basalt, USGS standard | 5.00 | 1.85 | 0.015 | 0.985 | 98.5% |
| Bir-1a | Basalt, USGS standard | 0.10 | 0.04 | 0.003 | 0.997 | 99.7% |
| DTS-2b | Dunite, USGS standard | 5.00 | 77.50 | 0.023 | 0.977 | 97.7% |
| DTS-2b | Dunite, USGS standard | 1.00 | 15.50 | 0.011 | 0.989 | 98.9% |
| DTS-2b | Dunite, USGS standard | 0.10 | 1.55 | 0.015 | 0.985 | 98.5% |
| DNC-1a | Dolerite, USGS standard | 5.00 | 1.35 | 0.007 | 0.993 | 99.3% |
| DNC-1a | Dolerite, USGS standard | 0.10 | 0.03 | 0.014 | 0.986 | 98.6% |
| CPI Cr | CPI International pure Cr standard | 0.10 | 100.00 | 0.006 | 0.994 | 99.4% |
| CPI Cr | CPI International pure Cr standard | 0.01 | 10.00 | 0.017 | 0.983 | 98.3% |
a
Sample dissolution in 125 μl of 2 M HNO3 at ~100°C for 2 h followed by dilution in MilliQ H2O and addition of 3 wt% H2O2 to give a total volume of 0.5 ml of 0.5 M HNO3 +3 wt% H2O2. This aliquot was subsequently stored at room temperature for 5 days prior to column loading.
b
Sample dissolution in 250 μl of 10 M HCl at 140 °C for >18 h followed by dilution to a total volume of 5 ml of 0.5 M HCl using cold (5°C) MilliQ H2O immediately prior to column loading.
c
Fe was removed from the sample matrix by means of an anion exchange procedure in 6 M HCl according to Bizzarro et al. [26], in which Cr (III) has no preference for the exchanger.