Reference materials were randomly incorporated into the routine samples to monitor analytical accuracy, precision, and any potential drift or offsets between batches. This approach also helped identify other types of analytical artifacts.
The reference materials used in this process were UPDEEP_SPRU_BARK_DRY, UPDEEP_SPRU_NEED_DRY, and UPDEEP_SPRU_TWIG_DRY. These materials were developed in-house as reference samples representing the three primary types of materials. While they do not adhere to international reference material standards, they have undergone multiple analyses by external laboratories to establish reliable reference values.
Additionally, the international reference material CLV-2 had been used.
Below are the results for the reference values of these three reference materials:
| Element | UPDEEP_SPRU_BARK_DRY | UPDEEP_SPRU_NEED_DRY | UPDEEP_SPRU_TWIG_DRY |
|---|---|---|---|
| Ag | 0 | 0 | 0 |
| As | 10 | 10 | 10 |
| B | 10 | 10 | 10 |
| Ba | 10 | 10 | 10 |
| Be | 0 | 0 | 0 |
| Bi | 10 | 0 | 1 |
| Ca | 10 | 10 | 10 |
| Cd | 10 | 10 | 10 |
| Ce | 10 | 10 | 10 |
| Co | 10 | 10 | 10 |
| Cr | 10 | 10 | 10 |
| Cs | 10 | 10 | 10 |
| Cu | 10 | 10 | 10 |
| Dy | 10 | 10 | 10 |
| Er | 10 | 10 | 10 |
| Eu | 10 | 10 | 10 |
| Fe | 10 | 10 | 10 |
| Ga | 10 | 10 | 10 |
| Gd | 10 | 10 | 10 |
| Ge | 10 | 1 | 9 |
| Hf | 8 | 0 | 5 |
| Hg | 10 | 0 | 0 |
| Ho | 10 | 10 | 10 |
| In | 0 | 0 | 0 |
| K | 10 | 10 | 10 |
| La | 10 | 10 | 10 |
| Li | 0 | 0 | 0 |
| Lu | 0 | 3 | 2 |
| Mg | 10 | 10 | 10 |
| Mn | 10 | 10 | 10 |
| Mo | 10 | 10 | 10 |
| Na | 10 | 10 | 10 |
| Nb | 10 | 10 | 10 |
| Nd | 10 | 10 | 10 |
| Ni | 10 | 10 | 10 |
| Pb | 10 | 7 | 10 |
| Pd | 0 | 0 | 0 |
| Pr | 10 | 10 | 10 |
| Pt | 0 | 0 | 0 |
| Rb | 10 | 10 | 10 |
| Re | 0 | 0 | 0 |
| Sb | 10 | 0 | 10 |
| Sc | 0 | 0 | 0 |
| Se | 8 | 4 | 7 |
| Sm | 10 | 10 | 10 |
| Sn | 1 | 0 | 0 |
| Sr | 10 | 10 | 10 |
| Ta | 10 | 10 | 10 |
| Tb | 10 | 6 | 10 |
| Te | 5 | 2 | 2 |
| Th | 10 | 10 | 10 |
| Ti | 10 | 10 | 10 |
| Tl | 10 | 10 | 10 |
| Tm | 0 | 0 | 0 |
| U | 10 | 10 | 10 |
| V | 10 | 10 | 10 |
| W | 1 | 1 | 1 |
| Y | 10 | 10 | 10 |
| Yb | 10 | 10 | 10 |
| Zn | 10 | 10 | 10 |
| Zr | 10 | 10 | 10 |
The aforementioned reference materials were randomly added to the sample set as supplementary samples within the larger batch of routine samples. Because of their random inclusion, both the sequence and order of the samples varied, as did the total number of measurements taken.
| ParentSampleID | N |
|---|---|
| UPDEEP_SPRU_NEED_DRY | 16 |
| UPDEEP_SPRU_BARK_DRY | 15 |
| CLV-2 | 19 |
| UPDEEP_SPRU_TWIG_DRY | 16 |
The results of the measurements of the reference samples provide the following:
| Element | CLV-2_Mean | CLV-2_Median | CLV-2_RSD | CLV-2_RMAD | UPDEEP_SPRU_BARK_DRY_Mean | UPDEEP_SPRU_BARK_DRY_Median | UPDEEP_SPRU_BARK_DRY_RSD | UPDEEP_SPRU_BARK_DRY_RMAD | UPDEEP_SPRU_NEED_DRY_Mean | UPDEEP_SPRU_NEED_DRY_Median | UPDEEP_SPRU_NEED_DRY_RSD | UPDEEP_SPRU_NEED_DRY_RMAD | UPDEEP_SPRU_TWIG_DRY_Mean | UPDEEP_SPRU_TWIG_DRY_Median | UPDEEP_SPRU_TWIG_DRY_RSD | UPDEEP_SPRU_TWIG_DRY_RMAD |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ag | 1.7e+01 | 1.7e+01 | 20 | 10 | 8.8e+00 | 8.6e+00 | 13 | 10 | 2.6e+00 | 2.9e+00 | 46 | 37 | 1.1e+01 | 1.2e+01 | 14 | 17 |
| Al | 1.1e+02 | 1.1e+02 | 13 | 11 | 9.3e+01 | 9.2e+01 | 6 | 6 | 7.6e+01 | 7.3e+01 | 15 | 6 | 9.4e+01 | 9.1e+01 | 14 | 11 |
| As | 3.4e+02 | 3.4e+02 | 15 | 17 | 3.0e+02 | 2.9e+02 | 11 | 13 | 1.0e+02 | 9.7e+01 | 18 | 17 | 5.2e+02 | 5.2e+02 | 8 | 6 |
| Au | 8.6e-01 | 5.2e-01 | 145 | 79 | 1.9e-01 | 1.5e-01 | 73 | 84 | 2.3e-01 | 2.5e-01 | 69 | 74 | 9.0e-01 | 2.1e-01 | 193 | 105 |
| B | 3.1e+01 | 4.2e+01 | 49 | 47 | 2.1e+00 | 1.9e+00 | 50 | 5 | 3.1e+00 | 2.8e+00 | 48 | 12 | 4.2e+00 | 2.6e+00 | 61 | 8 |
| Ba | 2.3e+04 | 2.3e+04 | 8 | 8 | 1.2e+05 | 1.2e+05 | 4 | 4 | 4.1e+04 | 4.1e+04 | 4 | 5 | 6.7e+04 | 6.6e+04 | 5 | 5 |
| Be | 4.7e+00 | 4.2e+00 | 50 | 33 | 1.5e+00 | 1.6e+00 | 46 | 52 | 4.6e+00 | 4.4e+00 | 27 | 28 | 1.3e+00 | 1.4e+00 | 36 | 30 |
| Bi | 9.8e+00 | 9.2e+00 | 21 | 19 | 8.9e+00 | 8.8e+00 | 16 | 18 | 3.3e+00 | 2.9e+00 | 77 | 38 | 4.1e+00 | 3.8e+00 | 52 | 56 |
| Ca | 7.5e+03 | 7.7e+03 | 8 | 5 | 1.0e+04 | 1.0e+04 | 8 | 10 | 5.4e+03 | 5.5e+03 | 7 | 7 | 4.0e+03 | 4.1e+03 | 6 | 4 |
| Cd | 1.3e+01 | 1.3e+01 | 23 | 15 | 1.3e+02 | 1.3e+02 | 7 | 6 | 1.4e+01 | 1.4e+01 | 14 | 11 | 4.2e+01 | 4.2e+01 | 8 | 10 |
| Ce | 2.3e+02 | 2.2e+02 | 10 | 9 | 7.6e+01 | 7.5e+01 | 10 | 6 | 1.7e+01 | 1.7e+01 | 8 | 11 | 7.7e+01 | 7.6e+01 | 12 | 12 |
| Co | 6.7e+01 | 7.0e+01 | 13 | 9 | 1.3e+02 | 1.3e+02 | 8 | 10 | 8.2e+01 | 8.1e+01 | 8 | 8 | 2.4e+02 | 2.3e+02 | 11 | 7 |
| Cr | 3.9e+02 | 3.8e+02 | 10 | 7 | 1.4e+02 | 1.4e+02 | 7 | 8 | 6.1e+01 | 4.9e+01 | 103 | 18 | 3.0e+02 | 3.0e+02 | 11 | 12 |
| Cs | 1.8e+01 | 1.7e+01 | 20 | 18 | 3.7e+01 | 3.7e+01 | 13 | 5 | 7.0e+01 | 6.9e+01 | 13 | 18 | 8.2e+01 | 8.2e+01 | 7 | 7 |
| Cu | 2.0e+03 | 1.9e+03 | 13 | 7 | 5.1e+03 | 5.1e+03 | 2 | 2 | 1.4e+03 | 1.4e+03 | 5 | 5 | 5.9e+03 | 5.8e+03 | 4 | 3 |
| Dy | 1.4e+01 | 1.4e+01 | 12 | 11 | 4.7e+00 | 4.8e+00 | 18 | 24 | 3.2e+00 | 3.2e+00 | 19 | 15 | 5.2e+00 | 5.3e+00 | 16 | 11 |
| Er | 6.4e+00 | 6.5e+00 | 15 | 17 | 2.5e+00 | 2.6e+00 | 21 | 23 | 1.7e+00 | 1.8e+00 | 27 | 13 | 2.8e+00 | 2.8e+00 | 22 | 22 |
| Eu | 4.2e+00 | 3.6e+00 | 37 | 44 | 1.7e+01 | 1.8e+01 | 23 | 4 | 6.0e+00 | 6.3e+00 | 25 | 10 | 8.1e+00 | 9.6e+00 | 48 | 33 |
| Fe | 2.6e+02 | 2.5e+02 | 9 | 7 | 9.2e+01 | 9.4e+01 | 6 | 7 | 4.0e+01 | 4.0e+01 | 6 | 8 | 1.2e+02 | 1.2e+02 | 4 | 5 |
| Ga | 5.3e+01 | 3.2e+01 | 53 | 37 | 6.6e+00 | 6.7e+00 | 61 | 75 | 6.7e+01 | 6.9e+01 | 26 | 14 | 1.6e+01 | 1.5e+01 | 31 | 16 |
| Gd | 1.0e+01 | 9.8e+00 | 12 | 12 | 5.4e+00 | 5.1e+00 | 24 | 25 | 2.5e+00 | 2.3e+00 | 25 | 17 | 5.3e+00 | 5.1e+00 | 20 | 21 |
| Ge | 2.8e+00 | 2.7e+00 | 41 | 36 | 2.9e+00 | 3.0e+00 | 29 | 26 | 5.3e+00 | 5.4e+00 | 30 | 15 | 1.3e+01 | 1.7e+01 | 64 | 15 |
| Hf | 3.4e+00 | 2.6e+00 | 86 | 31 | 9.0e-01 | 8.0e-01 | 41 | 45 | 3.1e-01 | 2.3e-01 | 90 | 68 | 1.2e+00 | 1.1e+00 | 29 | 24 |
| Hg | 2.8e+01 | 2.9e+01 | 14 | 14 | 1.7e+02 | 1.7e+02 | 5 | 5 | 2.8e+01 | 2.8e+01 | 10 | 6 | 2.5e+01 | 2.5e+01 | 8 | 9 |
| Ho | 2.6e+00 | 2.6e+00 | 8 | 5 | 1.1e+00 | 1.1e+00 | 19 | 20 | 7.9e-01 | 8.4e-01 | 22 | 16 | 1.0e+00 | 1.0e+00 | 19 | 19 |
| In | 4.7e-01 | 4.2e-01 | 45 | 56 | 3.8e-01 | 3.4e-01 | 65 | 101 | 1.7e-01 | 1.4e-01 | 80 | 69 | 2.4e-01 | 1.9e-01 | 97 | 80 |
| K | 3.7e+03 | 3.8e+03 | 9 | 4 | 9.0e+02 | 8.9e+02 | 7 | 7 | 4.0e+03 | 3.9e+03 | 7 | 8 | 3.8e+03 | 3.8e+03 | 4 | 2 |
| La | 1.2e+02 | 1.1e+02 | 12 | 8 | 6.4e+01 | 6.5e+01 | 8 | 5 | 2.3e+01 | 2.3e+01 | 7 | 6 | 6.4e+01 | 6.5e+01 | 7 | 7 |
| Li | 1.8e+02 | 1.7e+02 | 20 | 15 | 1.0e+01 | 1.0e+01 | 27 | 12 | 1.9e+01 | 1.9e+01 | 13 | 10 | 3.3e+01 | 3.4e+01 | 13 | 13 |
| Lu | 4.9e-01 | 4.4e-01 | 39 | 43 | 2.6e-01 | 1.9e-01 | 79 | 44 | 1.2e-01 | 1.1e-01 | 66 | 62 | 2.9e-01 | 1.9e-01 | 105 | 37 |
| Mg | 8.2e+02 | 8.6e+02 | 12 | 5 | 2.2e+02 | 2.3e+02 | 13 | 20 | 8.2e+02 | 8.2e+02 | 10 | 12 | 9.0e+02 | 9.0e+02 | 9 | 9 |
| Mn | 1.7e+06 | 1.8e+06 | 9 | 7 | 3.8e+05 | 3.8e+05 | 4 | 4 | 1.1e+06 | 1.1e+06 | 3 | 2 | 5.4e+05 | 5.4e+05 | 4 | 2 |
| Mo | 7.1e+01 | 7.1e+01 | 15 | 14 | 1.4e+01 | 1.3e+01 | 28 | 19 | 3.1e+01 | 3.1e+01 | 16 | 11 | 3.0e+01 | 2.9e+01 | 17 | 8 |
| Na | 7.4e+00 | 7.2e+00 | 33 | 38 | 7.6e+01 | 7.8e+01 | 7 | 8 | 3.0e+01 | 3.1e+01 | 8 | 8 | 4.9e+01 | 5.0e+01 | 8 | 4 |
| Nb | 9.7e+00 | 1.2e+01 | 54 | 76 | 3.6e+00 | 3.2e+00 | 40 | 19 | 8.6e-01 | 8.4e-01 | 39 | 11 | 6.2e+00 | 4.0e+00 | 62 | 18 |
| Nd | 9.7e+01 | 1.0e+02 | 13 | 11 | 3.7e+01 | 3.6e+01 | 12 | 15 | 1.4e+01 | 1.4e+01 | 16 | 14 | 4.4e+01 | 4.3e+01 | 16 | 19 |
| Ni | 5.2e+02 | 5.0e+02 | 25 | 11 | 7.5e+02 | 7.5e+02 | 9 | 8 | 6.6e+02 | 6.9e+02 | 11 | 9 | 2.3e+03 | 2.2e+03 | 18 | 3 |
| P | 8.8e+02 | 9.1e+02 | 9 | 6 | 1.8e+02 | 1.8e+02 | 10 | 10 | 1.4e+03 | 1.5e+03 | 8 | 7 | 1.1e+03 | 1.1e+03 | 7 | 4 |
| Pb | 1.1e+03 | 1.1e+03 | 10 | 7 | 1.2e+03 | 1.2e+03 | 6 | 7 | 6.9e+01 | 6.8e+01 | 17 | 9 | 4.6e+02 | 4.5e+02 | 12 | 7 |
| Pd | 2.3e+00 | 1.5e+00 | 94 | 138 | 6.4e+00 | 6.6e+00 | 29 | 18 | 4.5e+00 | 4.8e+00 | 29 | 12 | 3.5e+00 | 4.4e+00 | 66 | 37 |
| Pr | 2.5e+01 | 2.5e+01 | 12 | 11 | 9.8e+00 | 9.7e+00 | 11 | 16 | 3.6e+00 | 3.6e+00 | 10 | 12 | 1.1e+01 | 1.1e+01 | 16 | 17 |
| Pt | 1.2e-01 | 3.9e-02 | 146 | 136 | 1.7e-01 | 2.0e-01 | 74 | 99 | 2.0e-01 | 1.1e-01 | 80 | 116 | 1.8e-01 | 1.8e-01 | 65 | 75 |
| Rb | 2.9e+03 | 3.0e+03 | 7 | 4 | 4.2e+03 | 4.2e+03 | 3 | 4 | 1.0e+04 | 1.0e+04 | 5 | 3 | 1.2e+04 | 1.2e+04 | 3 | 3 |
| Re | 2.6e+01 | 2.6e+01 | 6 | 3 | 4.4e-02 | 3.5e-02 | 67 | 100 | 3.6e-02 | 2.1e-02 | 99 | 120 | 3.1e-02 | 2.3e-02 | 77 | 96 |
| Sb | 3.9e+01 | 3.4e+01 | 39 | 36 | 2.6e+01 | 2.4e+01 | 37 | 20 | 6.5e+00 | 5.5e+00 | 67 | 25 | 2.9e+01 | 2.1e+01 | 59 | 22 |
| Se | 3.5e+02 | 3.9e+02 | 50 | 37 | 3.7e+01 | 2.8e+01 | 99 | 117 | 3.3e+01 | 1.9e+01 | 100 | 131 | 6.1e+01 | 5.1e+01 | 86 | 130 |
| Sm | 1.8e+01 | 1.8e+01 | 17 | 9 | 7.0e+00 | 7.0e+00 | 14 | 13 | 2.9e+00 | 2.6e+00 | 33 | 36 | 8.0e+00 | 8.5e+00 | 23 | 16 |
| Sn | 7.4e+01 | 5.1e+01 | 139 | 33 | 1.7e+01 | 1.6e+01 | 29 | 28 | 4.3e+00 | 2.9e+00 | 97 | 80 | 1.2e+01 | 1.3e+01 | 64 | 68 |
| Sr | 1.7e+04 | 1.7e+04 | 8 | 6 | 2.7e+04 | 2.7e+04 | 3 | 3 | 1.9e+04 | 1.9e+04 | 3 | 3 | 2.1e+04 | 2.1e+04 | 6 | 3 |
| Ta | 5.6e-01 | 4.8e-01 | 72 | 69 | 1.6e+00 | 1.6e+00 | 45 | 51 | 9.0e-01 | 4.9e-01 | 144 | 101 | 1.7e+00 | 1.4e+00 | 53 | 23 |
| Tb | 2.6e+00 | 2.6e+00 | 15 | 18 | 1.1e+00 | 1.0e+00 | 25 | 18 | 5.9e-01 | 5.8e-01 | 24 | 31 | 1.0e+00 | 9.8e-01 | 20 | 17 |
| Te | 1.1e+01 | 7.6e+00 | 91 | 101 | 8.2e+00 | 6.0e+00 | 61 | 30 | 5.8e+00 | 5.9e+00 | 16 | 22 | 4.5e+00 | 4.8e+00 | 37 | 32 |
| Th | 4.5e+01 | 4.4e+01 | 15 | 21 | 6.0e+00 | 5.7e+00 | 25 | 12 | 1.9e+00 | 1.5e+00 | 86 | 44 | 6.2e+00 | 5.8e+00 | 24 | 26 |
| Ti | 2.3e+03 | 2.3e+03 | 19 | 15 | 3.1e+03 | 3.0e+03 | 12 | 16 | 8.9e+02 | 8.2e+02 | 23 | 15 | 4.1e+03 | 4.1e+03 | 15 | 9 |
| Tl | 1.4e+01 | 1.5e+01 | 21 | 22 | 1.6e+01 | 1.6e+01 | 12 | 6 | 3.1e+01 | 3.0e+01 | 11 | 6 | 3.8e+01 | 3.7e+01 | 17 | 16 |
| Tm | 6.7e-01 | 8.0e-01 | 40 | 41 | 1.6e-01 | 1.6e-01 | 31 | 35 | 1.1e-01 | 9.7e-02 | 48 | 48 | 2.4e-01 | 1.8e-01 | 58 | 45 |
| U | 2.9e+03 | 3.1e+03 | 15 | 11 | 2.3e+00 | 2.4e+00 | 20 | 17 | 5.2e-01 | 4.1e-01 | 93 | 56 | 2.3e+00 | 2.3e+00 | 18 | 25 |
| V | 3.0e+02 | 3.1e+02 | 9 | 8 | 2.4e+02 | 2.4e+02 | 4 | 4 | 4.8e+01 | 4.7e+01 | 18 | 22 | 2.3e+02 | 2.3e+02 | 6 | 6 |
| W | 1.1e+02 | 7.8e+01 | 88 | 29 | 4.2e+00 | 3.6e+00 | 47 | 30 | 9.1e-01 | 9.0e-01 | 44 | 35 | 4.3e+00 | 4.2e+00 | 21 | 26 |
| Y | 6.1e+01 | 6.3e+01 | 13 | 11 | 3.1e+01 | 3.0e+01 | 16 | 12 | 3.2e+01 | 3.1e+01 | 20 | 28 | 3.3e+01 | 3.3e+01 | 14 | 12 |
| Yb | 4.9e+00 | 4.9e+00 | 18 | 19 | 2.1e+00 | 2.1e+00 | 28 | 25 | 1.2e+00 | 1.1e+00 | 41 | 46 | 2.2e+00 | 2.2e+00 | 34 | 33 |
| Zn | 6.3e+04 | 6.3e+04 | 7 | 3 | 1.0e+05 | 1.0e+05 | 3 | 3 | 5.6e+04 | 5.5e+04 | 2 | 2 | 8.6e+04 | 8.7e+04 | 3 | 3 |
| Zr | 8.4e+01 | 8.0e+01 | 16 | 18 | 3.8e+01 | 4.0e+01 | 15 | 16 | 7.4e+00 | 8.1e+00 | 70 | 81 | 4.4e+01 | 4.4e+01 | 23 | 16 |
The preanalysed values are provided from the measurements of the reference material powder at external labs, in this case ACTLAB.
Figure 1.1: X-charts of UPDEEP_SPRY_NEED_DRY/UPDEEP_SPRY_TWIG_DRY/UPDEEP_SPRY_BARK_DRY SRMs analysed with the routine samples (dots) vs. the preanalysed SRM values (mean as solid line, 1st standard deviation as dashed line.) The lines of the predefined values are missing if the SRM values were below detection limit. See Table 1.1 for the numbers of the preanalysed SRMs and their missing values. The two laboratory batches (A20-02249, A20-02250) are distinquised by colour.
Figure 1.2: X-charts of UPDEEP_SPRY_NEED_DRY/UPDEEP_SPRY_TWIG_DRY/UPDEEP_SPRY_BARK_DRY SRMs analysed with the routine samples (dots) vs. the preanalysed SRM values (mean as solid line, 1st standard deviation as dashed line.) The lines of the predefined values are missing if the SRM values were below detection limit. See Table 1.1 for the numbers of the preanalysed SRMs and their missing values. The two laboratory batches (A20-02249, A20-02250) are distinquised by colour.
Figure 1.3: X-charts of UPDEEP_SPRY_NEED_DRY/UPDEEP_SPRY_TWIG_DRY/UPDEEP_SPRY_BARK_DRY SRMs analysed with the routine samples (dots) vs. the preanalysed SRM values (mean as solid line, 1st standard deviation as dashed line.) The lines of the predefined values are missing if the SRM values were below detection limit. See Table 1.1 for the numbers of the preanalysed SRMs and their missing values. The two laboratory batches (A20-02249, A20-02250) are distinquised by colour.