test 1
double-beam
A ____________________ spectrophotometer can hold two cuvettes, one for the sample and the other for the blank or reference sample.
prisms gratings
A differentiating factor between prisms and gratings, is that __________ are NONLINEAR and ____________ are LINEAR.
3 2
A differentiating factor between prisms and gratings, is that in order to calibrate a prism, ________ different wavelengths must be checked. In contrast, when calibrating a grate, _______ different wavelengths must be checked.
nebulization
A technique related to atomic absorption that converts the sample into a fine spray or aerosol white it is being introduced into the flame.
decreases
As monochromicity decreases, linearity ____________.
decreases
As the amount of stray light increases, linearity _____________.
absorbed transmitted
As the concentration of the compound in a solution increases, more light is ____________ by the solution and less light __________.
atoms
Atomic absorption spectrophotometry measures concentration of electromagnetic radiation by __________ rather than molecules.
concentration logarithm
Beer's Law states that the ____________ of a substance is directly proportional to the amount of light absorbed by that substance OR is inversely proportional to the ____________ of the transmitted light.
inversely logarithm
Beer's Law states that the concentration of a substance is directly proportional to the amount of radiant energy ABSORBED by that substance or is _______________ proportional to the ______________ of TRANSMITTED radiant energy.
blank for background interference such as lipemia, hemolysis, etc.
Bichromatic analysis is used in automation to: A. blank for background interference B. decrease testing time C. measure samples twice at timed intervals D. Verify wavelength calibration
background blank
Bichromatic analysis minimizes _______________ interference (such as hemolysis or icteria) by providing a ___________ for each specimen.
broadened intensity purity
By increasing the width of the exit slit, the bandwidth of the emerging light is _________, with a resultant increase in energy _____________ but with a decrease in spectral ____________.
greater
Flameless AA instruments have (greater or less) sensitivity than flame AA instruments?
The use of filters or solutions with sharp cut-off wavelengths can detect stray light.
How can stray light be detected?
**fluorometry has two monochromators to select the excitation wavelength and the emission wavelength **detector is at right angles to the excitation beam in order to avoid measuring transmitted light
How does fluorometry differ from spectrophotometry?
It is used to measure the light transmitted by a solution in order to determine the concentration of light-absorbing substances in that solution.
How is a spectrophotometer used in clinical chemistry?
chemical reactions drying on a carbon platform
Other atomization processes can replace the flame in AA absorption. Name them.
**stable source of radiant energy (light) **entrance slit to focus light **wavelength selector (monochromator or filter) **exit slit to focus light **device to hold cuvette which holds sample **radiant energy detector **device to read out the electrical signal generated by the detector
List the components of a single-beam spectrophotometer.
doubled twice
If the concentration of a solution is constant and the path length through the solution which the light must pass is doubled, then the effect on the ABSORBANCE is the same as __________ the concentration because __________twice as many absorbing molecules are now present in the radiant energy path.
**change the light source **verify wavelength calibration **sealing light leaks **realign instrument components **clean optical surfaces
If the presence of stray light is detected, how can it be corrected?
atomized
In AA flame photometry, once the sample is nebulized, it is then ____________, or converted into an atomic vapor.
it is NOT excited in the flame, but is dissociated from its chemical bond.
In AA spectrophotometry the ionic form (is, or is not) excited in the flame?
vapor
In AA spectrophotometry, the sample solution must be converted into a ____________.
1 cm
Most cuvettes have internal dimensions (path length) of __________.
***variation from sample to sample due to temp, solvent composition, viscosity, etc **chemical interference due to the formation of compounds that are not completed dissociated in the flame
Name sources of error in atomic absorption.
Ultraviolet (UV) 180 to 390 nm Visible light 390 and 780 nm
Name the two areas of the electromagnetic spectrum that are commonly used in the chemical laboratory.
**maintaining a homogeneous suspension in the path of the light beam **assumption that all of the suspended particles are the same size
What are disadvantages of turbidimetry and nephelometry?**
**particle size standard in not the same as the particle size in samples **particles may settle out as measurements are being made
What are some sources of error in turbidimetry?
**more specific than chromogenic methods **is more specific because the secondary monochromator selects only the emitted wavelength of light.
What are the advantages of fluorometry over absorption spectrophotometry?
Entrance slit Dispersion device (can be either prism or grating) Exit slit
What are the three components of a monochromator?
barrier layer (photo voltaic cells) photomultiplier tube photodiodes
What are the three types of photo detectors?
E = h x v OR E = h x c / λ E = Energy h = Planck's Constant (6.62 x 10^-27) v = frequency c = velocity (3 x 10^10) λ = wavelength
What are the two formulas that calculate the ENERGY of a photon?
gratings and prisms
What are the two types of dispersion devices that be may be found monochromators?
**Very elevated concentrations are measured. **Incident radiant energy is not monochromatic. **The solvent absorption is significant compared with the solute absorbance. **Stray light. **The sides of the cell(cuvete) are not parallel.
What can cause deviations from Beer's Law?
The oxidation of: luminol esters acridinium THINK: LEAD is a dangerous CHEM dioxetaines
What causes chemiluminescence?
Filter (old method) or monochromator (more common now)
What component of a spectrophotometer isolates the required wavelength or range of wavelengths needed for a specific analyte?
to make the light parallel and reduce stray radiation
What is a common purpose of both the entrance slit and the exit slit in a PHOTOMETER?
NiSO4
What is an example of a solution that can be used to detect stray light?
**monochromators give a much narrower range of wavelengths than filters can **monochromators are easily adjustable over a wide spectral range
What is the advantage of using monochromators en lieu of filters?
To disperse radiant energy from the source lamp into a spectrum from which the desired wavelength is isolated by mechanical slits.
What is the function of a monochromator?
Unlike fluorescence, chemiluminescence does not need excitation radiation or monochromators
What is the main difference between fluorescence and chemiluminescence?
AA absorbs, fluorescence emits.
What is the main difference between fluorometry and atomic absorption?
stray light
What is the most common issue that causes deviations from Beer's Law?
photomultiplier tube
What is the most common type of photo detector and is used because it experiences less fatigue, show rapid response time, and is very sensitive?
hydrogen deuterium lamp
What kind of light source lamp emits a continuous spectrum and used for the UV region of the spectrum (180-390)?
deuterium lamp
What kind of light source lamp emits more intensity than the hydrogen lamp and is used for the UV region of the spectrum (180-390).
mercury vapor lamp
What kind of light source lamp is best for discontinuous wavelength or line spectrum?
Lamp with tungsten HALIDE filaments
What kind of light source lamp is longer lasting, produces more light at short wavelengths, and emits a higher intensity than tungsten filament lamps?
Incandescent lamp with a tungsten filament
What kind of light source lamp is most commonly used?
mercury vapor lamp
What kind of light source lamp is used for high performance liquid chromatography?
Beer's Law
What law states that the concentration of a substance is directly proportional to the amount of radiant energy absorbed by that substance.
flame photometry and fluorometric methods
What methods of photometry use the principle of ABSORPTION ENERGY?
glass
What type of cuvette is suitable for wavelengths between 320 to 950 nm?
quartz (silica) Note: can also be used for higher ranges
What type of cuvette should be used for measurement of <320 nm?
Holmium oxide or didymium
What type of filters may be used to check wavelength calibration?
fluorometry
What type of instrumentation is based on the principle of measuring energy emission that occurs when compounds absorb electromagnetic radiation, become excited, and return to energy levels lower than their original energy levels?
fluorometry
What type of instrumentation is very susceptible to quenching interference?
Atomic absorption spectrophotometry
What type of instrumentation's principle is based on vaporized atoms in the ground state that absorb light at very narrowly defined wavelengths? (0.001 to 0.01 nm in width)
H+ or deuterium lamps
What type of lamps have built-in sources for checking wavelength accuracy?
hydrogen discharge or deuterium lamp
What type of light source must a spectrophotometer have in order to measure an substance within the UV range of the wavelength spectrum?
incandescent lamp with a tungsten filament
What type of light source must a spectrophotometer have in order to measure an substance within the visible range of the wavelength spectrum?
antigen-antibody complexes
What types of samples are typically analyzed in nephelometry?
fluorometry up to a 1000 x more
Which is more sensitive, colormetric methods or fluorometry?
100%
To convert T to %T, the denominator and numerator are multiplied by _________.
lanthanum
To reduce source of error in atomic absorption, the effect of tightly complexing anions can be minimized or eliminated when _________ is added to the sample to displace calcium from the complex.
True
True or False Beer's Law may not be followed if the absorbance of a fluorescent solution is being measured.
True
True or False The presence of a cell phone near a spectrophotometer may cause incorrect readings.
spectrophotometry
The measurement of the intensity of light at selected wavelengths.
tungsten lamp
The most common light source for spectrophotometry in the visible range is: A. Didymium lamp B. Deuterium lamp C. Hydrogen discharge lamp D. Tungsten lamp
frequency (v)
The number of cycles occurring per second and is obtained by the relationship: frequency = velocity/wavelength
first slit
Which slit in a MONOCHROMATOR is located at the entrance and focuses on the light on the grating or the prism where it can be dispersed with a minimum of stray light?
exit slit
Which slit in a MONOCHROMATOR is located at the exit and determines the bandwidth of light that will be selected from the dispersed spectrum?
Beer's Law A = abc A= absorbance a=absorptivity b=light path of the solution in centimeters (usually a value of 1) c=concentration of substance of interest
_________ __________ is the mathematical relationship that connects absorbance of radiant energy concentration of a solution path length.
turbidimetry
__________ measures the amount of light blocked by the particulate matter as light passes through the cuvette by a colorimeter or spectrophotometer.
bichromatic analysis
___________ is a methodology of spectrophotometry in which absorbance is measured at two different wavelengths.
photomultiplier tube
___________ is an electron tube that is capable of significantly amplifying a current.
quenching
____________ occurs when the excited molecule interacts with a substance in the solution and loses some of its energy. This is common in fluorometry.
nephelometry
_____________ measures the light that is scattered by suspended particles at right angles to the beam incident to the cuvette.
stray light
________________ is radiant energy that reaches the detector at wavelengths other than those indicated by the monochromator setting.
photometry
the measurement of the intensity of light without regard to wavelength
velocity(c)
varies with the medium through which the radiant energy is passing
inversely logarithmically
%T (transmitted) varies _________ and __________ with concentration.
nonlinear less
A prism is _________ becomining ________ linear at longer wavelengths (over 550 nm).
Zeeman correction
A process that corrects for background absorption in flameless AA.
prisms gratings
A spectrophotometer is an instrument that uses ___________ or _________ to isolate wavelength
Tungsten filament lamp
A type of light source that emits a spectrum of radiant energy from 360 to 950 nm.
Tungsten IODIDE lamp
A type of light source that emits a spectrum of radiant energy of the visible and near-UV range (390 - 780 nm)
path length
Absorbance is directly proportional to the ___________ ____________ of the radiant energy through the cell(cuvete).
color component
According to Beer's Law, when a substance's concentration is measured with a spectrophotometer, under suitable conditions, the amount of light absorbed by a solution when illuminated with light of a proper wavelength, is directly proportional to the concentration of its ____________ _____________.
sensitive precise trace metals
An advantage of AA spectrophotometry is that it is very _________ and _________ and it routinely used to measure concentration of _______ ____________ that are not easily excited.
light source wavelength
An advantage of flameless AA is that the same __________ and _________ is used to measure the total and background absorptions.
glass
Glass filters are composed of one or more layers of colored __________.
hollow cathode
In atomic absorption, the source emitting radiant energy is a _________ ___________ lamp.
fixed variable
In diffraction grating monochromators, the exit slit may be of _________ width, resulting in a __________ bandpass. In contrast, prism monochromators, have _______ exit slits.
(C) Light (radiant energy) is generated from light source (F) Light passes through entrance slit (A) Light passes through the dispersion device (i.e. prism or grating) (E) Light passes through exit slit (D) Light passes through sample, some of which is absorbed (B) Light that is not absorbed by sample reaches the detector
In regard to the process flow of a spectrophotometer, place the following in the proper order: (A) Light passes through the dispersion device (i.e. prism or grating) (B) Light that is not absorbed by sample reaches the detector (C) Light (radiant energy) is generated from light source (D) Light passes through sample, some of which is absorbed (E) Light passes through exit slit (F) Light passes through entrance slit
Visible ultraviolet infrared
In spectrophotometry, measurements may be made in what three ranges?
absorption absorbance
In the equation, A=abc, A is absorbance and a is absorptivity. The difference between absorbance and absorptivity is that __________ is the fraction of radiation absorbed at a specific wavelength and _________ is the concentration of the substance being analyzed.
photometer
Instrument that uses filters to isolate wavelength range.
curvilinear
Once a chromagen has proven to follow Beer's Law at a specific wavelength, a graphical plot of %T (transmittance) vs C (concentration) will be _____________.
linear
Once a chromagen has proven to follow Beer's Law at a specific wavelength, a graphical plot of A (absorbance) vs C (concentration) will be _____________.
chemiluminescence
Part of chemical energy generated produces excited intermediates that decay to ground state with emission of photons.
light
Radiant energy means ________________.
photons
Radiant energy or light, behaves as if it is composed of discrete energy packets called ______________.
Wratten gelatin
The ____________ filter is a type of filter that is found in older labs. It consists of colored ___________ between clear glass plates/
Rayleigh
The ____________ theory says that if the wavelength of light is approximately equal to the size of the particle, more light is scattered forward than backward.
Absorption Spectrum
The absorption of radiant energy that plots the absorbance as a function of the wavelength.
number size
The amount of scatter in nephelometry is related to the _____ and ____ of the particles.
wavelength (λ)
The distance transversed by one complete wave cycle and is usually given in nanometers
variable wavelength
The energy of a photon is _____________ and depends on the frequency of _____________ of radiant energy.
line spectrum
The entire absorption spectrum of atoms is called a _____.
Absorption Spectrum
The graphical plot of absorbance vs wavelength.
As/Au = Cs/Cu As = Absorbance of standard Au = Absorbance of unknown Cs = Concentration of standard Cu = Concentration of unknown
The linear relationship between absorbance and concentration makes it possible to determine unknown concentrations with what formula?
bandpass
The range of wavelengths passed by a filter or monochromators and is expressed as the range of wavelengths transmitted at a point equal to one half of the peak intensity transmitted. (Also called bandwidth).
white light 390 and 780
The visible region is also known as ___________ and its region of the electromagnetic spectrum is between _________ and ____________ nm.
