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提问人:网友nimmmmni 发布时间:2022-01-07
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In plant and animal systems, is it the same of the definition and inclusion for essential elements? Why?

A、The definition and inclusion for essential element are not the same in plant and animal systems.

B、Because the trace elements essential for plants are those elements which cannot be substituted by others in their specific biochemical roles and that have a direct influence on the organism so that it can neither grow nor complete some metabolic cycle.

C、In general, B, Co, Cu, Fe, Mn, Mo, Si and Zn are known to be essential for plants, whilst Al, As, Br, F, I, Li, Ni, Rb, Se, Sr, Ti and V are known to be essential for some groups or species. In human and animal systems, trace elements are defined as being essential if depletion consistently results in a deficiency syndrome and repletion specifically reverses the abnormalities.

D、The trace elements fulfilling these requirements are As, Co, Cr, Cu, F, Fe, I, Mn, Mo, Ni, Se, Si, Sn, V and Zn.

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What are the characteristics of ideal analytical technique for measuring trace elements in environmental samples?

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B、d. possible matrix or interference effects; e. total dissolved solids content; f. liquid or solids analysis; g. required levels of precision and accuracy;

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第5题
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B、Atomic absorption spectrometry (flame or electrothermal) (AAS, ET-AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma optical (or atomic) emission spectrometry (ICP-OES or ICP-AES), neutron activation analysis (NAA), X-ray fluorescence (XRF), proton-induced X-ray emission (PIXE), spark source or isotope dilution mass spectrometry (SSMS, IDMS), electrochemical (anodic stripping voltammetry and polarography) or inductively coupled plasma-mass spectrometry (ICP-MS).

C、The main limitations for most of these analytical methods are sensitivity or precision problems due to interferences and sample matrix effects.

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What are the factors that affect the choice of analytical method for making trace element measurements of environmental or biological samples?

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B、The choice of analytical method for making trace element measurements of environmental or biological samples depends not only on availability but on a variety of factors: a. multi or single element determination; b. required detection or determination limits; c. required type of sample preparation; d. possible matrix or interference effects;

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第9题
In plant and animal systems, is it the same of the definition and inclusion for essential elements? Why?
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第10题
Write down the approaches of determination of trace elements in environmental sample. What are their limitations? How to reduce or eliminate these problems?
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