Analytical Methods

Question 1

Light Amplification by Stimulated Emission of Radiation

Light source for spectrophotometry

Answer 1

LASER

Question 2

Deuterium lamp
Mercury arc
Xenon lamp
Hydrogen lamp

Answer 2

UV

Question 3

Most commonly used monochromator

Cutting grooves

Answer 3

Diffraction gratings

Question 4

Meas. light intensity in a narrower wavelength

Answer 4

Spectrophotometric meas.

Question 5

Meas. light intensity w/o consideration of wavelength
Multiple wavelength (uses filter only)

Answer 5

Photometric measurement

Question 6

Anti-stray light

Answer 6

Cutoff filter

Question 7

Most commonly used cuvet

Answer 7

Alumina silica glass cuvet

Question 8

½ peak transmittance

Answer 8

Bandpass

Question 9

Converts transmitted light into photoelectric energy

Answer 9

Photodetector

Question 10

Simplest detector
No external voltage
For filter photometers

Answer 10

Barrier layer cell/ photocell/ photovoltaic cell

Question 11

A = abc (a = absorptivity; b = length of light (1cm); c = concentration)
A = 2 – log%T

Answer 11

Absorbance

Question 12

Meas. light emitted by a single atom burned in a flame
Principle: Excitation
Lt. source and cuvette: Flame
For excited ions (Na+, K+)

Answer 12

FEP

Question 13

Color of reagents

Answer 13

Reagent blank

Question 14

Reagent blank

Answer 14

Sample blank

Question 15

Splits monochromatic light into two components:
One beam –> sample
One beam –> reference soln or blank (corrects for variation in light source intensity)

Answer 15

Double beam spectro.

Question 16

2 photodetectors (sample beam and reference beam)

Answer 16

Double-beam in space

Question 17

1 photodetector

Monochromatic light  sample cuvet and reference cuvet

Answer 17

Double-beam in time

Question 18

Meas. light absorbed by atoms dissociated by heat
Principle: Dissociation (unionized, unexcited, ground state)
Lt. source: Hollow-cathode lamp
For unexcited trace metals (Ca++ and Mg++)
More sensitive than FEP

Answer 18

AAS

Question 19

Unknown sample is made to react with a known solution in the presence of an indicator

Answer 19

Volumetric (Titrimetric)

Question 20

Light blocked
Meas. abundant large particles (Proteins)
Depend on specimen concentration and particle size

Answer 20

Turbidimetry

Question 21

Meas. amt of Ag-Ab complexes
Scattered light
Depends on wavelength and particle size

Answer 21

Nephelometry

Question 22

Directly proportional to net charge

Inversely proportional to molecular size & viscosity of the supporting medium

Answer 22

Electrophoretic mobility

Question 23

Separation of steroids, barbiturates, blood, alcohol, and lipids
Volatile compounds
Specimens  vaporized
Mobile phase: Inert gases

Answer 23

Gas chromatography

Question 24

Relative distance of migration from the point of application
Rf = Distance leading edge of component moves
Total distance solvent front moves

Answer 24

Retention factor (Rf) value

Question 25

Det. amt. of lt. emitted by a molecule after excitation by electromagnetic radiation
Lt. sources: Mercury arc and Xenon lamp (UV)
Lt. detector: Photomultiplier tubes
2 monochromators:
Primary filter – selects wavelength absorbed by the solution to be measured
Secondary filter – prevents incident light from striking the photodetector
Sensitivity: 1000x than spectro

Answer 25

Fluorometry/Molecular Luminescence Spectro.