SPECTROPHOTOMETRY PART 2 Flashcards
- not routinely done
SPECIAL
excitation: unstable
FLAME PHOTOMETRY
ground state: emit (emission) radiant energy
FLAME PHOTOMETRY
heating: dissociation of atoms
FLAME PHOTOMETRY
ATOMIC ABSORPTION SPECTROPHOTOMETRY
Detection of trace elements
ATOMIC ABSORPTION SPECTROPHOTOMETRY
- in combination with proteins
mercury
: absorb (absorption) radiant energy
hollow cathode lamp
- allowed to pass through; converted to electrical signal
transmitted light
Light Source: FEP
Flame
Light Source: AAS
Hollow Cathode Lamp
State of atoms: FEP
Excited
State of atoms: AAS
Ground State
Energy measured: FEP
Thermal
Energy measured: AAS
Radiant
Basis of measurement: FEP
Light emission
Basis of measurement: AAS
Light absorbance
Sensitivity: FEP
Lesser
Sensitivity: AAS
Greater
- failure of the flame to dissociate the sample
- CHEMICAL INTERFERENCE
*unique trace elements in CHEMICAL INTERFERENCE
- Lanthanum
- Strontium
*calcium phosphate remedy:
displacement principle
- excitation instead of dissociation
- IONIZATION INTERFERENCE
*absorbs radiant energy at ground state = EXCITATION instead
- IONIZATION INTERFERENCE
*cause: HIGH TEMPERATURE
- IONIZATION INTERFERENCE
- interference on the absorption by evaporation of solvents or formation of solids
- MATRIX INTERFERENCE
*examples:
- Use of organic compounds
USE OF FLAMELESS AAS
carbon rod or graphite furnace
heated until dried/charred
FLAMELESS AAS
FLAMELESS AAS: dissociation of atoms
atomized
more sensitive
FLAMELESS AAS
permits determination of trace metals in small samples
FLAMELESS AAS
Atoms absorb light of a particular wavelength and emit light of a longer wavelength (lower energy)
FLOURESCENCE SPECTROPHOTOMETRY
USE OF FLOURESCENCE SPECTROPHOTOMETRY
Porphyrins, hormones, amino acids, vitamins, cathecolamines
FLOURESCENCE SPECTROPHOTOMETRY COMPONENTS
Energy: mercury or xenon arc lamp, slit 1 degree monochromator, quartz cuvettes, 2 degree monochromator, detector, readout device
- Xenon
- Entrance slit
- Primary monochromator
- Secondary filter
FLOURESCENCE SPECTROPHOTOMETRY
*absorption causes excitation
*light emission
*filtered by 2nd filter
*PHOTOMULTIPLIER TUBE
FLOURESCENCE SPECTROPHOTOMETRY
- has the ability to magnify the radiant energy converted to electical energy
*PHOTOMULTIPLIER TUBE
- excitation filter (intends to isolate the specific wavelength of light: short wavelength, high intensity/energy)
Primary monochromator
- an energy emission that occurs when certain compounds absorbs electromagnetic radiation become excited and then return to an energy levelnthat is usually slightly hugher than their original level
FLOURESENCE
- emitted energy is equal to or lower than the absorbed energy
PHOSPHORESCENCE
absorbs short wavelength, high energy, great intensity
excitation (unstable)
ground state
emit radiant energy
XENON LAMP
measurement of light blocked by a suspension of particulate matter
TURBIDIMETRY
measurement of the reduction in light transmission caused by particle formation
TURBIDIMETRY
protein determination
TURBIDIMETRY
TURBIDIMETRY PRECIPITATION AGENTS
(turbid solution)
Sulfosalicylic acid and Trichloroacetic acid
Factors affecting turbidimetry and nephelometry:
Size and number of particles
The depth of the tube
Cross-sectional area of each particle
- measure turbidity of samples to detect bacterial growth in broth cultures
MICROBIOLOGY ANALYZERS
- measure the antibiotic sensitivity from such cultures
MICROBIOLOGY ANALYZERS