Table 1:
Relative standard deviation percentages of metal standards and Afzal samples
| Metal | International standard | Afzal | ||||||
|---|---|---|---|---|---|---|---|---|
| 1 at 5 ppb conc. | 2 at 10 ppb conc. | 3 at 20 ppb conc. | 4 at 30 ppb conc. | 5 at 50 ppb conc. | Sample 1 | Sample 2 | Sample 3 | |
| Cr | 1.13 | 0.67 | 0.42 | 0.93 | 0.58 | 1.19 | 1.88 | 1.04 |
| Ni | 2.46 | 2.50 | 0.74 | 1.29 | 1.47 | 3.78 | 3.35 | 3.74 |
| Cd | 0.85 | 1.87 | 1.28 | 1.09 | 1.03 | 8.13 | 1.78 | 8.14 |
| Pb | 2.83 | 1.31 | 0.65 | 0.53 | 1.34 | 1.62 | 1.28 | 1.24 |
ppb = parts per billion; conc. = concentration; Cr = chromium; Ni = nickel; Cd = cadmium; Pb = lead.