Trace and Toxic Elements (F)
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When are trace elements considered essential?
If a deficiency impairs a biochemical or fxnal process and replacement of element corrects impairment
Essential trace elements are associated w/ what?
W/ an enzyme or other protein as an essential component or cofactor
Excess concs. of essential trace elements are associated w/ what?
W/ some degree of toxicity
What are the exs of trace elements (in mg/L)?
1) Iron 2) Copper 3) Zinc
What are the exs of ultratrace elements (w/c are
1) Selenium 2) Chromium 3) Manganese
What is the characteristic of non-essential trace elements?
These are of medical interest
Why are non-essential trace elements of medical interest?
Because many of them are toxic
Sxs must be collected w/ what (in connection w/ sx collection and processing)?
W/ scrupulous attention to details (such as anticoagulant, collection apparatus, and sx type)
What is the characteristic of trace elements in biologic sxs?
These are of low conc.
What is the characteristic of trace elements in environment?
These are ubiquitous
Since trace elements are of low conc. (in biologic sxs) and ubiquitous (in environment), what must be done (in connection w/ sx collection and processing)?
Much care must be taken (to avoid contaminating sxs)
What must be used (in terms of sx collection and processing)?
1) Special sampling 2) Collection devices 3) Specially cleaned glassware 4) H2O and rgnts of high purity
What must be done to the lab environment (in connection to sx collection and processing)?
It must be carefully controlled
How can the lab environment be carefully controlled (in connection w/ sx collection and processing)?
1) Placement of trace elements (in separate room) 2) Use of sticky mats (at doors) 3) Non-shedding ceiling tiles 4) Controlled air flow 5) Disposable booties
What are the methods for trace elements?
1) Atomic emission spectroscopy (AES) 2) Atomic absorption spectroscopy (AAS) 3) Inductively coupled plasma mass spectrometry (ICP-MS)
What are the 3 most impt components of AE spectrophotometer (in connection w/ AES)?
1) Source 2) Wavelength selecting device 3) Detector
What is the characteristic of the source (w/c is an impt component of AE spectrophotometer)?
It is sufficiently hot (to produce excited-state spp.)
What is the use of wavelength selecting device (as a most impt component of AE spectrophotometer)?
For spectral dispersion of radiation and separation of analytic line from other radiation
What is the action of the detector (as 1 of the most impt components of AE spectrophotometer)?
Permitting measurement of radiation intensity
What should be done to liquid sx containing element (in connection w/ AES)?
It is converted into an aerosol and delivered into source (where it receives energy to emit radiation)
The intensity of emitted radiation is correlated to what (in connection w/ AES)?
It is correlated to conc. of an analyte and is basis for quantitation
What is the flow of the simplified schematic of AES?
Flame or plasma (light emission) -> monochromator -> detector
What is AAS (what is its principle)?
It is an analytic procedure for quantification of elements through absorption of optical radiation by free atoms in gas phase Spectra of atoms are line spectra, sp. for absorbing elements
What are the 4 most impt components of AA spectrophotometer (in connection to AAS)?
1) Radiation light source 2) Atomizer 3) Monochromator 4) Detector