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Whole blood
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Whole blood from 31 non-smoking, healthy athletes (15 males, 16 females), living in Sweden, was analyzed (1). None of the subjects had any known exposure to trace elements. Blood was collected in the morning following fasting for 12 hours. The samples were supplied by the Institute of Medical Science, Uppsala, Sweden.
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The samples were digested with nitric acid in closed PFA containers in a microwave digestion system. After dilution with ultra-pure water, the digests were analysed by Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SFMS). The measurement time was about 8 min per sample.
Out of 50 elements included in the analysis, 29 (including e g thorium, thallium, and uranium) were detected in all samples and another 17 elements in the majority of samples. Some examples are given in Table 1. |
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Table 1. Examples of elemental concentrations (ng/ml) in whole blood from non-exposed subjects (n=31). For other elements, see Element List.
| Element |
Mean |
Std.Dev. |
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Element |
Mean |
Std.Dev. |
| Zinc |
5900 |
1000 |
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Titanium |
1.1 |
0.8 |
| Copper |
900 |
220 |
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Mercury |
2.0 |
1.3 |
| Iodine |
68 |
19 |
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Cadmium |
0.12 |
0.09 |
| Selenium |
180 |
30 |
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Antimony |
0.26 |
0.16 |
| Lead |
17 |
8 |
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Uranium |
0.015 |
0.006 |
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The accuracy of the analytical method was assessed by a combination of different approaches, namely 1) analysis of three external reference materials, 2) analysis of samples from an interlaboratory comparison program (from Le centre de toxicologie du Québec, Canada), and 3) comparisons with other analytical techniques (ICP-AES and GFAAS). |
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The sector ICP-MS technique (ICP-SFMS, high-resolution ICP-MS) is advantageous in analyses of body fluids compared to conventional quadrupole ICP-MS. In the latter technique, a large number of spectral interferences occur, calling for special corrections which add to the uncertainty in the results, or even making the determination impossible. Elements for which accuracy thus can be improved using higher mass resolution include the following:
Aluminium
Arsenic
Selenium
Silicon
Scandium
Titanium
Vanadium
Chromium
Manganese
Cobalt
Nickel
Copper
Zinc
Gallium
Germanium
It should be noted that quadrupole instruments equipped with so-called collision or reaction cells is an alternative to high-resolution for some, but not all of the above elements. |
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After some improvements in the method, a second study (6) was carried out comprising 60 elements. Special care was taken to minimize extraneous contamination by avoiding metal, glass, and rubber in vessels for blood storage. A number of elements could be determined with lower detection limits than in the first study. Results for IAEA A-13 Freeze Dried Animal Blood were compared to "target ranges" (according to the certificate) and to results from other authors. Results are given in Table 2 (for a freshly opened batch), showing good agreement except for nickel. For this element the target range is probably in error. Low values are also reported by Barany et al (J. Anal. At. Spectrom. 12 (1997) 1005).
Table 2. Results for IAEA A-13 (Freeze Dried Animal Blood). Standard deviation in parentheses. Concentrations apply to the dry material.
| Element |
Found |
Target range |
| Bromine µg/g |
21.9 (0.9) |
19-24 |
| Copper µg/g |
3.9 (0.09) |
3.7-4.8 |
| Nickel ng/g |
5.2 (0.7) |
600-1400 |
| Lead ng/g |
159 (5) |
140-300 |
| Rubidium µg/g |
2.34 (0.05) |
1.7-3.1 |
| Selenium ng/g |
272 (25) |
150-310 |
| Zinc µg/g |
11.2 (0.28) |
12-14 |
For the majority of trace and ultra-trace elements, ALS Scandinavia's ICP-SFMS results tend to agree with the lower edges of previously published ranges for unspiked reference and laboratory intercomparison samples. A possible explanation for this is that earlier results were more affected by extraneous contamination.
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In a third study, whole blood, together with serum and urine, from 12 apparently healthy volunteers (6 males, 6 females, living in Sweden and covering the age interval 5-61 years), was analyzed (7). None of the subjects had any known exposure to trace elements. The analysis comprised 64 elements, 61 of which were detected in at least in part of the whole blood samples. Largely, the results agreed well with previously published data. However, much lower concentrations were found for a number of elements (Ti, Ni, Zr, Ce, Ga, Ta, Nb, Y, Bi, La, Hf, Nd, Pr, and Tb), which might be explained by contamination in earlier analyses (cf below).
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Recommendations for sampling and sample handling
Special care must be taken to prevent contamination. Generally, sample handling (addition of chemicals and transfer between containers) should be minimized. The risk of metals release from surfaces of materials in contact with the sample must be observed. Needles contribute especially chromium, nickel, cobalt, and manganese. Glass should generally be avoided for storage. For metals in very low concentrations, adsorption to container walls may cause measurable losses with time. Special collection tubes for trace element analysis should be used, though commercially available tubes cannot generally be assumed to be suitable for all elements. Results from testing of different evacuated collecting tubes and other devices used for blood and serum are given in Reference 3. Especially, it was concluded that commercially available collecting tubes should be avoided if elements such as barium, aluminium, thorium and rare earth elements are to be accurately determined.
ALS Scandinavia routinely provides containers for samples that are to be sent to the laboratory for analysis.
Cooling or freezing of samples will reduce metal release from containers. It should however be noted that freezing causes breaking up of red cells, which precludes subsequent separation of these. |
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