U3 LAB: INSTRUMENTATION Flashcards
Four Major Disciplines of Analytic Techniques
- Spectrometry
- Luminescence
- Electroanalytic methods
- Chromatography
under Spectrophotometry
- Spectrophotometry
- Flame Emission Spectrophotometry
- Atomic Absorption
Measures intensity of light or light transmitted
Spectrophotometry
Spectrophotometry
directly proportional to concentration
Absorbance
Spectrophotometry
inversely proportional to concentration
Transmittance
Measures intensity of light after an ion is burned (light of a single atom)
Flame Emission Spectrophotometry
Principle of Flame Emission Spectrophotometry
excitation of electrons from lower to higher energy
Measure of light absorbed after ions are dissociated by heat
Atomic Absorption
Atomic Absorption is used to measure?
trace elements (Ca, Mg)
Measures the light produced when ions are excited to unexcited
Fluorometer
Luminescence
Material absorbs at high energy but short wavelength, emits light at lower energy (visible light)
Fluorescence
Luminescence
Measures analyte produced in the reaction vessels
Chemiluminescence
Chemiluminescence produces?
electromagnetic radiation of UV, visible, infrared
Luminescence
Chemical yields electronically excited intermediate/product responsible for the emission
Chemiluminescence
Luminescence
for proteinous analytes
Nephelometry
Luminescence
measures the light scattered by a particulate matter suspended in a solution
Nephelometry
Luminescence
Most common example of Nephelometry
measurement of antigen-antibody complexes (turbidimetry)
Separation of molecules by their molecular weight
Electrophoresis
This refers to separation techniques for soluble components in a solution by specific differences in physical or chemical characteristics.
Chromatography
Separation of compounds that are naturally volatile or chemically converted to a volatile form
Gas Chromatography
Beer Lambert’s Law
concentration of analyte is directly proportional to absorbance
The darker the sample?
the higher concentration, intensity, absorbance
<400nm
Ultraviolet (UV)
400-700nm
Visible Light
> 700nm
infrared
750-1600nm
mid IR / fingerprint region
longer wavelength, _____ energy and frequency
lower
shorter wavelength, _________ energy and frequency
higher
Planck’s Formula
E = hv
Planck’s Formula
E
energy of photon in Joules
Planck’s Formula
h (constant)
6.626 x 10-34
Planck’s Formula
v
frequency of electromagnetic radiation
Beer Lambert’s Law
What is inversely proportional?
Transmittance and absorbance
T/F: A solution transmits light corresponding in wavelength to its color, and usually absorbs light of wavelengths complementary to its color.
True
This minimizes unwanted stray light.
Entrance slit
This eliminates unwanted wavelengths.
Monochromater
Holds the solution
Cuvette
Two types of Light Source
- Continuum Source
- Line Source
Continuum Source
- Tungsten
- Deuterium
- Xenon
Continuum Source
Most common for visible infrared light sources
Tunsgten
Continuum Source
Routinely used for UV based light sources
Deuterium
Continuum Source
Used in most spectrofluorometers
Xenon
under Line source
Mercury-vapor lamps
Light under infrared region
Silicon Carbide
Stray light is considered as?
- any wavelength outside band
- causes absorbance error
- limits the maximum absorbance
- most common cause of lost linearity
Stray light can come from?
deteriorating light source
Kinds of Monochromator
- Prisms
- Diffraction Gratings
- Filters
- Holographic Gratings
Kinds of Monochromator
made up of glass
Prisms
Kinds of Monochromator
has grooves
Diffraction Gratings
This controls the width of the light beam.
Exit slit
Described as the total range of wavelengths transmitted
bandpass
Cuvette is also known as?
Analytical / Absorption / Sample Cell
Kinds of Cuvette
- Alumina Silica Glass
- Quartz Plastic
- Borosilicate glass
- Soft glass
Kinds of Cuvette
most common, wide range absorbance
Alumina Silica Glass