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PHA222 > UV/molecular spec > Flashcards

UV/molecular spec Flashcards

1
Q

List 4 advantages of UV spec

A

Simple
Relatively cheap
Rapid
Sensitive

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2
Q

List 3 limitations of UV spec

A
  • prone to interferences
  • limited to drugs having a chromophore
  • non-specific
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3
Q

How can specificity of UV spec be improved?

A

modifying analyte and exploiting spectral change

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4
Q

Describe the bathochromic shift (red)

A

shift to longer wavelength/lower energy

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5
Q

Describe the hypsochromic shift (blue)

A

shift to shorter wavelength/higher energy

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6
Q

Hyperchromic shift is an increase/decrease in absorbance

A

increase

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7
Q

Hypochromic shift is an increase/decrease in absorbance

A

decrease

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8
Q

State the Beer-Lambert law

A

For a given molecule, absorbance is proportional to concentration of sample

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9
Q

What solutions does the Beer-Lambert law apply to?

A

dilute solutions (<0.01M)

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10
Q

When is it suitable to use the calibration curve method?

A

If unknown concentrations vary

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11
Q

List 2 limitations of the calibration curve method

A
  • requires a pure standard

- time consuming

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12
Q

List 2 advantages of the calibration curve method

A
  • reduces error by doing several measurements for each standard
  • slope gives molar absorptivity
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13
Q

When is it suitable to use the comparative method?

A

If standard & sample values are close

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14
Q

State the calculation used for the comparative method

A

A sample / Conc sample = A std / Conc std

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15
Q

List 2 limitations of the comparative method

A
  • requires pure standard

- assumes linearity

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16
Q

Give an advantage of the comparative method

A

Fairly rapid

17
Q

State what is required for the absolute method

A

Specific absorbance

High quality instrument

18
Q

State a limitation of the absolute method

A
  • assumes linearity
19
Q

List 2 advantages of fluorescnce

A
  • sensitive

- specific

20
Q

List 5 limitations of fluorescence

A
  • limited linear range
  • relatively few molecules fluoresce
  • prone to interferences e.g. quenching
  • very solvent sensitive
  • very sensitive to pH
21
Q

List 4 applications of fluorescence

A
  • selective, sensitive detector for HPLC
  • chemiluminescence
  • assay of medicines with low levels of active
  • limit for Al in water

PHA222 (7 decks)

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