What is percent transmittance (%T)?
The ratio of the radiant energy transmitted (T) divided by the radiant energy incident on the sample (I0).
What factors can affect the absorptivity of a molecule?
Molecular structure and the way absorbing molecules react with different energies.
p.5
Fluorometry Applications
What is the role of a mechanical attenuator in fluorometry?
It controls light intensity.
p.3
Spectrophotometry Principles
Which lamps are commonly used for ultraviolet (UV) work?
Deuterium discharge lamp and mercury arc lamp.
p.5
Fluorometry Applications
How much more sensitive is fluorometry compared to most spectrophotometric methods?
Approximately 1000 times more sensitive.
p.1
Analytical Chemistry Fundamentals
What is the foundation for all measurements made in modern clinical laboratories?
Analytical techniques and instrumentation.
p.6
Electrochemistry Basics
What are the two types of electrochemical cells?
Galvanic cells and electrolytic cells.
p.4
Spectrophotometry Principles
What is the difference between a single beam and a double beam spectrophotometer?
A double beam spectrophotometer has a reference sample to serve as a standard.
p.4
Spectrophotometry Principles
What does wavelength accuracy indicate?
It indicates that the wavelength on the control dial matches the actual wavelength of light passed by the monochromator.
p.1
Spectrophotometry Principles
What are the three types of spectra discussed?
Continuous spectrum, emission spectrum, and absorption spectrum.
p.7
Electrochemistry Basics
What reaction does the CO2 electrode facilitate?
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-.
p.7
Electrochemistry Basics
What is electrophoresis?
The migration of charged solutes or particles in an electrical field.
p.7
Electrochemistry Basics
What does an osmometer measure?
The concentration of solute particles in a solution.
p.3
Spectrophotometry Principles
What are diffraction gratings used for in spectrophotometry?
They are commonly used as monochromators to separate light into component wavelengths.
p.5
Chemiluminescence Techniques
What are some advantages of chemiluminescence?
Subpicomolar detection limits, speed, ease of use, and simple instrumentation.
p.1
Spectrophotometry Principles
What is the relationship between wavelength and energy described by?
Planck's formula: e = hv.
p.6
Electrochemistry Basics
What is the function of a salt bridge in an electrochemical cell?
It connects two half-cells and allows the flow of ions.
p.6
Electroanalytical Methods
What is the purpose of ion-selective electrodes (ISE)?
To measure the electrical potential due to the activity of specific ions.
p.4
Fluorometry Applications
What is Stokes Shift in fluorometry?
The difference between the maximum wavelengths of excitation and emitted fluorescence.
p.5
Fluorometry Applications
What is a characteristic feature of mercury vapor lamps?
They emit a characteristic line spectrum.
p.5
Fluorometry Applications
What is a major disadvantage of fluorometry?
Fluorescence is very sensitive to environmental changes.
p.6
Spectrometry Techniques
What is a key characteristic of laser light?
It is polarized, coherent, and has a narrow spectral width.
p.1
Spectrophotometry Principles
What is the approximate wavelength range for visible light?
400 nm (violet) to 700 nm (red).
p.7
Electrochemistry Basics
What is the formula for the Nernst equation?
ε = ΔpH × RTln/F = ΔpH × 0.059 V.
p.7
Electrochemistry Basics
What is a gas sensing electrode commonly used for?
For the analysis of blood gases and serum electrolytes.
p.7
Electrochemistry Basics
What has largely replaced coulometric titrations for chloride determination?
Chloride ion-selective electrodes (ISEs).
p.7
Electrochemistry Basics
What is the Nernst equation used for?
To calculate the electromotive force (EMF) produced by reference and indicator electrodes.
p.1
Spectrophotometry Principles
What do bright emission lines in a spectrum indicate?
Specific wavelengths determined by the composition of the emitting substance.
p.7
Electrochemistry Basics
What are the three major types of ion-selective electrodes (ISEs)?
1. Inert metal electrodes in contact with a redox couple, 2. Metal electrodes that participate in a redox reaction, 3. Membrane electrodes.
p.4
Spectrophotometry Principles
What components are found in a Hollow-Cathode Lamp?
An evacuated gas-tight chamber containing an anode, a cylindrical cathode, and an inert gas.
p.3
Spectrophotometry Principles
What is the most common light source for visible and near-infrared work in a spectrophotometer?
The incandescent tungsten or tungsten-iodide lamp.
p.3
Spectrophotometry Principles
What is the function of a monochromator?
Isolation of individual wavelengths of light.
p.3
Spectrophotometry Principles
How does a photomultiplier tube (PM tube) enhance sensitivity?
It detects and amplifies radiant energy, attracting electrons to a series of dynodes that emit secondary electrons.
p.1
Spectrophotometry Principles
What does spectrophotometry measure?
Electromagnetic radiation.
p.4
Spectrophotometry Principles
What does flame photometry measure?
Light emitted by excited atoms, commonly used for determining concentrations of Na, K, and Li.
p.5
Fluorometry Applications
Why are incandescent tungsten lamps seldom used in fluorometry?
They release little energy in the UV region.
p.5
Analytical Chemistry Fundamentals
How are turbidimetric measurements made?
Using a spectrophotometer.
p.1
Analytical Chemistry Fundamentals
What are the basic disciplines within the field of analytical chemistry?
Spectrometry, Luminescence, Electroanalytical Methods, and Chromatography.
p.4
Spectrophotometry Principles
What is the purpose of an Atomic Absorption Spectrophotometer?
To measure concentration by detecting the absorption of electromagnetic radiation by atoms.
p.3
Spectrophotometry Principles
What material is typically used for cuvettes in the UV region?
Quartz, as it enables transmission of light in that region.
p.3
Spectrophotometry Principles
What is a phototube and how does it work?
A phototube contains photosensitive material that emits electrons when light energy strikes it.
What is the formula for absorbance according to Beer’s Law?
A = e × b × c, where e is molar absorptivity, b is the length of the light path, and c is the concentration of absorbing molecules.
p.2
Spectrophotometry Principles
What is the role of a spectrophotometer?
To measure the light transmitted by a solution to determine the concentration of the light-absorbing substance in the solution.
p.5
Fluorometry Applications
What do filter fluorometers measure?
Concentrations of solutions containing fluorescing molecules.
p.5
Fluorometry Applications
What is the relationship between the electrical output of the photodetector and fluorescent energy?
The electrical output is proportional to the intensity of fluorescent energy.
p.5
Fluorometry Applications
Which lamps are most frequently used as excitation sources in fluorometry?
Gas discharge lamps (Mercury and Xenon Arc).
p.3
Spectrophotometry Principles
What type of monochromator uses a simple glass prism?
A simple glass prism monochromator refracts light as it enters denser glass.
p.5
Fluorometry Applications
What is a significant advantage of fluorometry?
Increased specificity by selecting optimal wavelengths for absorption and fluorescence.
p.5
Analytical Chemistry Fundamentals
What is turbidity in the context of measurements?
The concentration of particulate matter in a sample.
How is the concentration of a substance related to the amount of light absorbed according to Beer’s Law?
It is directly proportional to the amount of light absorbed and inversely proportional to the logarithm of the transmitted light.
p.1
Spectrophotometry Principles
What do dark absorption lines in a spectrum indicate?
Wavelengths of light absorbed by a substance.
p.4
Spectrophotometry Principles
What modification is required for flameless atomic absorption?
An electric furnace is used for chemical bond breaking (electrothermal atomization).
p.5
Fluorometry Applications
What is fluorescence polarization?
Radiant energy that is polarized in a single plane.
p.6
Spectrophotometry Principles
What does nephelometry measure?
Light scattered by small particles at an angle to the incident beam.
p.7
Electrochemistry Basics
What is the purpose of calibration in pH measurement?
To standardize the system with electrodes in a buffer of pH 7.0 and then replace it with a buffer of a different pH.
p.6
Electroanalytical Methods
How is the electrical connection between the indicator and reference electrode achieved?
By allowing a small flow of electrolyte.
p.3
Spectrophotometry Principles
What is the purpose of the sample cell or cuvette in a spectrophotometer?
To maintain a constant light path for absorbance proportional to concentration.
p.6
Spectrophotometry Principles
What factors influence light scattering in nephelometry?
Wavelength and particle size.
How is absorbance (A) mathematically derived?
A = -log(I/I0) = log(100%) - log(%T).
p.4
Spectrophotometry Principles
What checks should be performed for spectrophotometer quality assurance?
Wavelength accuracy, stray light, and linearity.
p.4
Spectrophotometry Principles
What is stray light in the context of spectrophotometry?
Stray light refers to any wavelengths outside the band transmitted by the monochromator.
p.7
Electrochemistry Basics
What is the role of enzyme electrodes?
To catalyze specific chemical reactions using immobilized enzymes.
p.5
Fluorometry Applications
What is the purpose of double beam instruments in fluorometry?
To compensate for instability due to electric power fluctuations.
p.3
Spectrophotometry Principles
What is the function of a photodetector in a spectrophotometer?
To convert transmitted radiant energy into an equivalent amount of electrical energy.
p.5
Chemiluminescence Techniques
What is chemiluminescence?
The emission of photons from excited intermediates generated by chemical energy.
What does Beer’s Law describe?
The relationship between the absorption of light by a solution and the concentration of that solution.
