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Serum
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Serum from 12 apparently healthy volunteers (6 males, 6 females), living in Sweden and covering the age interval 5-61 years (mean 31y, S.D. 12y), was analyzed ( 7). None of the subjects had any known exposure to trace elements. Following clotting, serum was separated by centrifugation and decanted.
The samples were analyzed after dilution (1+9) with 0.14 M high-purity nitric acid in distilled de-ionized water. The analysis was performed by Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SFMS).
Out of 64 elements, 39 (including e g silver, antimony, tin, and vanadium) were detected in all samples, and another 20 elements were detected in part of the samples. Some examples are given in Table 3.
For the majority of elements determined, the results agreed well with previously published data. For some elements in serum, found concentrations were however much lower compared to previous reports. Possibly, earlier data were affected by contamination in pre-analytical steps. |
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Table 3. Examples of elemental concentrations (ng/ml) in serum from non-exposed subjects (n=12). For other elements, see Element List.
| Element |
Range |
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Element |
Range |
| Arsenic |
<0.5-3.6 |
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Nickel |
0.13-0.55 |
| Cadmium |
0.013-0.074 |
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Antimony |
0.027-0.063 |
| Chromium |
0.05-0.48 |
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Selenium |
74-90 |
| Copper |
740-1300 |
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Uranium |
0.0005-0.01 |
| Mercury |
0.21-1.3 |
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Zinc |
420-710 |
In the same paper ( 7), element concentrations are given for a human serum reference material (Seronorm Lot MI0181). This material was analyzed both after dilution as described above, and after microwave-assisted acid digestion according to the method used for whole blood. Except for bromine and iodine, there were no differences in the results between the preparation methods. This indicates that simple dilution is adequate for this sample type when using ICP-SFMS.
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A later study ( 10) focussed on 20 low abundant elements (including platinum group elements). Certain instrumental modifications providing enhanced instrument sensitivity, together with the use of ultra-pure reagents, enabled sub-ng/l detection limits for 13 elements. For 16 elements (Y, Zr, Nb, Ag, Sb, Hf, Ta, W, Os, Re, Ir, Pt, Au, Tl, Bi and U), the method was found to be adequate at physiological levels in human serum. Three pooled samples, each representing 30-35 adults living in different parts of Sweden, were analyzed after dilution 1:9 with 2% hydrochloric acid. Some examples are found in Table 4. While high mass resolution was found to improve accuracy for light platinum group elements, it was concluded that quadrupole ICP-MS on the whole should yield essentially equivalent results for elevated concentrations (e g >0,5 µg/l). |
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Table 4. Examples of elemental concentrations (ng/ml) in human serum (3 pools with 30-35 subjects in each). For other elements, see Element List.
| Element |
Range |
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Element |
Range |
| Silver |
0.11-0.17 |
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Antimony |
0.070-0.11 |
| Gold |
0.006-0.018 |
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Tantalum |
0.008-0.010 |
| Bismuth |
0.0016-0.0029 |
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Thallium |
0.018-0.021 |
| Platinum |
0.0017-0.016 |
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Uranium |
0.014-0.015 |
| Rhenium |
0.0025-0.0032 |
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Zirconium |
0.090-0.16 |
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