Spectrometry

Question 1

Qualitative analysis

Answer 1

• Identity or properties of the drug or substance

- Separation, isolation or purification required in most cases, but not all

Question 2

Quantitative analysis

Answer 2

How much substance is present

Question 3

Frequency

Answer 3

• How quickly light gets to you
• hertz (Hz) (1 cycle/sec)
• kilohertz (1000 cycle/sec)

Question 4

Wavelength

Answer 4

distance in meters between peak and trough

Question 5

Electromagnetic energy properties

Answer 5

waves, frequency, and wavelength

Question 6

1 micron = X meters

Answer 6

10^-6 meters

Question 7

1 nanometer = X meters

Answer 7

10^-9 meters (1 m)

Question 8

1 Angstrom = X meters

Answer 8

10^-10 meters

Question 9

Wavelengths of the visible part of the spectrum in nanometers

Answer 9

390 - 750 nm

Question 10

Wavelengths of the visible part of the spectrum in angstroms

Answer 10

4300 A (violet) - 7000 A (red)

Question 11

The shorter the wavelength, the _____ the frequency and the ____ higher the energy

Answer 11

The shorter the wavelength, the greater the frequency and the higher the energy.
Short wavelength = high energy = blue/violet light

Question 12

As molecules are exposed to light (or other energy) they can absorb energy by:

Answer 12

• electromagnetic excitation

- molecular vibrations

Question 13

electromagenetic excitation

Answer 13

electrons in the molecule goes from a low energy state to a higher energy state)

Question 14

molecular vibrations

Answer 14

each compound has natural vibration frequency

Simplest molecule of 2 atoms bound together, we can excite the electrons and they can vibrate, stretch, and bend

Question 15

After a molecule is excited it can release the energy in various forms

Answer 15

• heat (most common!)
• rupture of the molecule (washing a red shirt fades to pink when hung in the sun to dry)
• re-emission of energy as altered electromagnetic energy (fluorescence)

Question 16

The useful parts of the spectrum are:

Answer 16

• UV
• visible
• infrared radiation

Question 17

UV and visible absorption

Answer 17

electronic absorption (electrons in molecules are excited to a higher energy state)

Question 18

Infrared absorption

Answer 18

due to vibrational energies of a molecule: bending, stretching, and rotation (cannot see infrared)

Question 19

chromophores

Answer 19

Most molecules have chromophores that absorb light. Chromophores may be certain molecular groups, such as phenyl groups or double bonds.

Question 20

chromosphere

Answer 20

Parts of the molecule that allow it to absorb light/radiation.
Ie: phenyl group on a drug can be analyzed by UV radiation

Question 21

Basic Instrument Components of a Heme Oximeter

Answer 21

1) Energy source to produce, radiation (a deuterium [uv] or tungsten lamp [visible])
2) A system to select limited part of the spectrum (prism or grating)
3) Sample chamber
4) Detector

Question 22

prisms

Answer 22

Prisms slow down wavelengths of different waves of white light and reflect the colors of the rainbow

Question 23

Detector or Photomultiplier Tube

Answer 23

converts light energy to electrical energy

Question 24

For any compound, absorbance is proportional to:

Answer 24

• thickness of the cuvette (or light path)

- the concentration of the compound

Question 25

absorption

Answer 25

• Absorption is dependent on the probability of radiation causing an electron being excited in the substance.
• If coefficient is small, substance poorly absorbs light

Question 26

Light intensity across a cell

Answer 26

is an exponential decay

Question 27

Light intensity calculation

Answer 27

I=Ioe-kL

I = emergent light
Io = incident light
k = a constant
L = length of light path

Question 28

absorbance

Answer 28

log of the ratio of incident to emergent light

Io/I

Question 29

absorbance is referred to as

Answer 29

absorbance, extinction, or optical density