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Renal > Atomic spectroscopy > Flashcards

Atomic spectroscopy Flashcards

1
Q

what is sample extraction technology

A
  1. seperation of the metals for analysis from other components of urine
    - eg. solid phase extraction
    - analyte is retained or eluted selectively
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2
Q

what are the main contents of urine

A

water, urea, chloride, electrolytes, creatinine, uric acid, salts/ions, ammonia

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3
Q

what materials are used in solid phase extraction

A
  1. silica/alumina
  2. porous plastics and polymers
  3. ionic resins
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4
Q

what is Beers law and calibration used for

A

used ubiquitously in quality control

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5
Q

what is standard addition used for

A
  1. used as a counter to matrix effects (often seen in complex samples)
  2. sample +1 or multiple aliquots (set added volume) of a standard included
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6
Q

what is internal standard spiking used for

A
  1. used as a counter to sampling inconsistency (eg using Lvov platform)
  2. add known quantity of similar analyte (eg methanol/ethanol)
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7
Q

describe the applications of calibration

A

used in cases of:

  • response variation
  • difficulty in conditions reproduction (eg. urine compositional differences)
  • quality control and quality assurance
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8
Q

what is the theory of atomic absorption and emission spectroscopy

A
  1. non bonded electronic excitation
  2. principal of measurement
    - characteristic spectral lines
    - emission and absorption
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9
Q

what are the methods of atomic absorption and emission spectroscopy

A
  1. atomic absorption spectroscopy
  2. atomic emission spectroscopy
    - flame photometry
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10
Q

what are the properties of an atom defined by

A

Defined by associated electrons

- these are promoted or demoted depending on absorption or emission of energy

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11
Q

what is atomic emission

A
  1. state of an atom defined by 4 quantum numbers
    - principal (n), state (l), magnetic (m), spin (s)
  2. characteristic emission spectra (radiation)- composed of lines
    - line is 0.005nm
  3. line spectrum of atom- series related to occupancy of specific energy states by electrons
    - this can be demonstrated in an electron energy level diagram
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12
Q

what are spectral lines due to

A

due to difference between electron energy states

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13
Q

what is emitted radiation

A

specific l^ light generated by outer electrons on fall from various elevated excited states, called resonance lines

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14
Q

what is a photon

A 
a particle (quantum) of energy
- wavelength defines that energy
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15
Q

what can electrons do in relation to photons

A

electrons can absorb or give out photons

  • principle of flame photometry
  • principle of atomic absorption
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16
Q

describe atomic emission spectroscopy

A
  1. flame atomic emission spectrometry
  2. Kirchhoff and bunsen initiators
    MX (s) –> MX(g) –> M(g) + X (g)
    nebulise –> vaporise –> dissociate
    - resonance of light emitted
  3. emission line= emission resonance line
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17
Q

what are the requirements of an atomic emission spectrometer

A
  • small uniform sized droplets <20um
  • constant feed rate
  • clean samples
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18
Q

what other emission techniques could be used

A

plasma (Ar) excitation up to 8000K

  • inductively high frequency coupled
  • direct current
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19
Q

what chemical processes take place in a flame

A
  1. evaporation of solid particles in flame

2. gaseous phase equilibrium

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20
Q

what are the 2 types of plasma emission spectroscopy

A
  1. inductively coupled plasma unit

2. direct current plasma unit

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21
Q

describe what atomic absorption spectroscopy and flame atomic emission spectroscopy are used for

A
  1. very specific technique
  2. electronic excitation of volatilised dissociated atoms
  3. excitation achieved: electric glow discharge of hollow cathode lamp
  4. sample specific cathode element
22
Q

give 2 examples of radiation sources

A
  1. hollow cathode lamp

2. electrode less lamp

23
Q

what 2 factors does the Beer-lambert law look at

A

absorbance and increasing concentration

24
Q

how does absorption occur in FAAS

A
  1. polychromatic light is little use
  2. specificity achieved via monochromatic light
  3. the flame is the absorption cell
25
Q

how does an FAA spectrometer work

A
  1. monochromator/filter/grating selection varies by 1nm

2. detector only sees wavelength of interest

26
Q

what is the difference between atomic emission spectroscopy and atomic absorption spectroscopy

A
  1. atomic emission spectroscopy- a quantity of light is given out by the atom
  2. atomic absorption spectroscopy- a quantity of light is taken in by the atom
27
Q

give examples of atomic emission spectroscopy

A

flame photometry or plasma emission spectroscopy

28
Q

give examples of atomic absorption spectroscopy

A

FAAS, AAS

29
Q

which metals is flame photometry used for

A

used for Li, Na, K, Ca

30
Q

describe an alternative to flame (FAAS) method

A

graphite furnace

- Lvov platform: a shelf inside the graphite tube

31
Q

give examples of specialised atomisation

A
  1. glow discharge- solids
    - sputtering M(s) by Ar+(g)
  2. hydride atomisation- metalloids (As, Bi, Se)
    - gas + sample/NaBH4 –> burner tube
  3. cold vapour
    - eg. Hg –> Hg(g)
32
Q

what are rich and lean gas mixtures

A

fuel to oxidant ratios used to alter the ideal burn zone in the flame

33
Q

how is light used as energy

A

if a body gives off light of flux, Q, then its mass diminishes as Q/c^2
E= mc^2

34
Q

describe how the light signal from the D2 lamp works

A
  1. spinning chopper blocks and permits additional D2 lamp signal
  2. intermittent signal compensate for HCL fluctuations
35
Q

what does the flame produce

A

the flame contains and produces colour absorbing species

- eg. lithium is pink

36
Q

what is the continuum source correction

A

absorbance of materials in the flame which are energised by the deuterium lamp generate a signal
- this background can then be removed electronically

37
Q

what are spectral interferences

A
  1. overlap of emission and absorption lines (broad and narrow)
  2. combustion products
  3. simple matrix
  4. Ti, Zr, W, V, Mo, and b- form refractory oxides
  5. reversible reactions in the flame (poly atoms)
38
Q

what is the background of AES and AAS interference

A
  • flame: emission/absorption

- other elements, molecules, polyatoms

39
Q

what is the ionisation of AES and AAS interference

A

-ions don’t work well, need single atoms
M+ + e–> M
- suppression by using an electron liberator

40
Q

what is the matrix of AES and AAS interference

A
  • viscometric
  • salt effect
  • sequestration (eg. EDTA)
41
Q

what is optimal flame performance

A
  1. use pure nitric acid for digestion because they are quite soluble and are a good oxidising agent so will degenerate any organic material into water and various salts and co2
  2. all organic tissue that might act as contaminants/interferences will get degenerated into inorganic material
  3. produces a nitrate salt of the metal which is water soluble and oxidises organic material present to reduce matrix effects normally seen
42
Q

give examples of common chemical interference agents

A

oxides, silicates, aluminates, complex salts

43
Q

what is the role of AES and AAS interferences

A
  1. block light from passing through onto a detector
    - but the detector measures whether light is scattered away from the linear line that would normally hit the detector
    - means that it measures the scattering of light
    - more scattered it is, the more absorption there is, and the more absorption there is, the more interfering agents there are between the light and detector
44
Q

what would be useful to combat AES and AAS interferences

A

deuterium lamp- shines directly onto the detector in a straight line, and when it gets blocked, the detector sees the difference between the 2 lights

45
Q

how can interference be reduced

A
  1. elevation of burner temperature
  2. use preferential flame reaction binding
  3. stable chelated ions
  4. reducing environmental flame
46
Q

what is a preferential binding reaction

A

to avoid aluminium or silicon binding with strontium, can add a preferential binding agent such as lanthanum

47
Q

what are the advantages of microwave plasma atomic emission spectroscopy

A
  1. can be left unattended- no flames/expensive gas supply and handling of dangerous gas cylinders
  2. dramatically reduces operating cost
  3. superior detection limits and larger linear dynamic range compared to flame AA
  4. can set the detector to look for a specific wavelength of light and therefore the amount of light is related to the amount of ions and atoms of that species within the sample
48
Q

what is atomic spectroscopy quality control

A
  1. metal salts of drugs (Ca, Mg, Fe)
  2. highly toxic metals in consumed matter
  3. metal catalysts of oxidative changes
  4. metals used for pigments in pharmaceutical products
  5. electrolytes, kidney function tests
49
Q

give examples of radioisotope metals

A

Cr^51, Co^60

- many radoopharmaceuticals used in pharmacy

50
Q

what is ICH atomic spectroscopy for pharmaceutical analysis

A
  1. impurities profile studied for potential impurities
  2. degraded product according to ICH guidelines using analytical methods
    - estimation of trace level heavy metals by AAS
    - common metallic drugs
    - Au, Ag, Cu phosphines for cancer
    - barium sulphate, lithium carbonate
    - ferroquine- anti malarials
51
Q

give examples of other forms of atomic spectroscopy

A
  1. mass spectrometry
  2. x ray fluorescent spectrometry
    - use with almost all elements but very costly
    - often uses copper as a source of x rays

Renal (12 decks)

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