Analytical Techniques and Automation Flashcards
Describes the measurement principles used in the clinical chemistry laboratory
Analytic Techniques
Examples of analytic techniques
Spectrophotometry
Electrochemistry
Electrophoresis
Chromatography
Analytic techniques often used to determine concentrations of analytes in the CC lab
Spectrophotometry
Electrochemistry
Described as photons of energy traveling in waves
Electromagnetic radiation
Most recognizable forms of electromagnetic radiation
Light and radiant energy
Other types of electromagnetic radiation
Gamma rays
X-rays
Microwaves
Ultraviolet radiation
Radiofrequency
Radiation
The linear distance between any two equivalent points on a successive wave
Wavelength
Unit used in the visible spectrum
Nanometer nm
The relationship between wavelength and energy (E) is described by
Planck’s formula
Planck’s formula
𝐸 = h𝑣
Planck’s constant value
6.62 x10^-27 erg/sec
Unit of energy in the centimeter gram second system unit
erg
Is erg an SI unit?
No
h in the Planck’s formula
Planck’s constant
v in Planck’s in formula
Frequency
Number of oscillations of the waveform in a second
Frequency
Changes that occur in a period of time. Movement of waveform
Oscillation
Relationship between wavelength and frequency
Inversely proportional
Relationship between energy of electromagnetic radiation and wavelength
Inversely proportional
Wavelength of visible region
400-700nm
Wavelength of ultraviolet region
<400nm
Wavelength of infrared region
> 700nm
Visible region falls in between
Color violet (set at 400nm) and red (at 700nm)
States that the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the algorithm of the transmitted light
Beer’s Law
Converts the radiant energy into equivalent electrical energy
Photodetector
Function of sample cuvette
Contain the sample
Function of light source
Strikes the sample in the cuvette
Formula for % transmittance
% transmittance = T/I x 100
T in % transmittance formula
Radiant energy transmitted/ transmitted light
I in % transmittance formula
Radiant energy incident of the sample/ incident light
Amount of energy absorbed by the sample
Incident light (I)
Radiant energy that strikes photodetector
Transmitted light (T)
It refers to the amount of light absorbed
Absorbance
Formula for absorbance
𝐴 = 𝜀 ×𝑏 × 𝑐
𝜀 in absorbance formula
Molar absorptivity
b in absorbance formula
Length of the light path through the solution
c in absorbance formula
Concentration of absorbing molecules
Relationship between absorbance and concentration of the absorbing molecules or analyte of interest
Directly proportional
Equipment used to measure the light transmitted by a solution
Spectrophotometer
Function of spectrophotometer
Determine the concentration of the light absorbing substance in the solution
Components pf spectrophotometer
light source
Monochromator
Sample cell or cuvet
Photodetector
Meter or read-out device
Function of light source
Provides polychromatic light
What is polychromatic light
Light of several wavelengths. Variation in the color formation
Light source for visible and near-infrared region use
Incandescent tungsten or tungsten-iodide lamp
Light source for UV region use
Dueterium lamp and memory arc lamp
Light source will depend on the wavelength. True or False?
True
2 types of light source
Continuum
Line
Type of light source that emits radiation that changes in intensity
Continuum
Examples of continuum light source
Tungsten (visible region)
Dueterium (UV region)
Xenon (visible and UV region)
Type of light source that emits a few discrete lines or bands of radiation
Line
Examples of line light source
Mercury and sodium vapor
lamps (UV and visible)
Hollow cathode lamp (atomic absorption spectroscopy/ spectrophotmetry)
Function of monochromator
Isolates individual wavelengths of light
When light source strikes the monochromator, light source will produce ______
Polychromatic lights
Wavelength in nanometers (nm) at peak transmittance
Nominal wavelength
Range of wavelength about one half peak transmittance
Spectral bandwidth (FWHM or full width at half peak maximum)
Area from one point of a wave to another
Bandpass
Total length of wavelength
Bandpass
Shape and material for sample cuvette
Round or square; made of material that is transparent to radiation
Path length of sample cuvette
1 cm
Types of materials used for cuvette and their respective region of use
Fused silica or quarts: UV region
Alumina-silicate glass: 350-2000 nm
wavelength
Plastic cuvette: visible region
Double-beam spectrophotometers has how many cuvette?
Two cuvets (one for the sample and one for the solvent)
Function of photodetector
Converts the transmitted radiant energy into an equivalent amount of electrical energy
Types of photodetector
Barrier-layer cell or photocell (selenide cell)
Phototube
Photomultiplier tube (PMT)
Phototransistors and Photodiode
The least expensive; temperature sensitive photodetector
Barrier-layer cell or photocell
Composition of Barrier-layer cell or photocell
Selenium on a plate of iron
Barrier-layer cell or photocell is mainly used in _____
Filter photometers
Photodetector that contains cathode and anode enclosed in a glass tube
Phototube
Photodetector that has photosensitive material that gives off electrons when light energy strikes it
Phototube
Most common type of photodetector
Photomultiplier tube (PMT)
Characteristics of Photomultiplier tube (PMT)
200 times more sensitive than the phototube
Highly sensitive to UV and visible radiation
Characteristics of Photodiode
Not as sensitive as PM tube but has excellent linearity and speed
Beam of light that strikes the photodetector reflect the amount of analyte present in the sample
Linearity
Concentration of analyte can immediately be displayed in the digital meter because it can immediately convert amount of radiant energy into an equivalent energy
Speed
Function of meter or read-out device
Displays output of the detection system
Examples of meter or read-out device
Digital meters
d’Arsonval meters
Recorders
Light-emitting diodes (LEDs)
Cathode-ray tubes (CRTs)
Liquid crystal displays (LCDs)
Simplest type of absorption spectrometers
Single-beam spectrophotometer
Function of single-beam spectrophotometer
Measure one measurement at a time at one specified wavelength
Components of single-beam spectrophotometer
Light source
Monochromator
Sample cuvette
Photodetector (PM tube)
Read out device or meter
Components of double-beam spectrophotometer
Light source
Monochromator
Sample cuvette
Reference Cuvette
Photodetector (PM tube)
Read out device or meter
Spectrophotometer design that uses 2 photodetectors, 2 sample cuvettes
Double beam in space
Spectrophotometer design that uses 1 photodetector; chopper is used to pass the monochromatic radiation through the sample cuvette and then to the reference cuvette
Double-beam in time
A device that rotates or breaks up radiation beams so the beam of light can pass through the photodetector
Chopper
This implies that a photometer is measuring at the wavelength that it is set to
Wavelength or photometric accuracy
Material used to measure wavelength or photometric accuracy
Special glass-type optical filters:
Didymium glass (600 nm)
Holmium oxide (360 nm)
A test using glass filters or solutions that have known absorbance values for a specific wavelength
Absorbance check
The ability of a photometric system to yield a linear relationship between the radiant power incident upon its detector and the concentration
Linearity
Linearity is monitored using _____
Optical filters or solutions
Any light that impinges upon the detector that does not originate from a polychromatic light source (an interference)
Stray light
The presence of stray light is checked using _____
Special cut-off filters
Measures concentration by detecting the absorption of electromagnetic radiation by atoms rather than by molecule
Atomic Absorption Spectrophotometer
When using AAS, sample should be ___
Atomized
Light source for AAS
Hollow-cathode lamp
Electrodeless discharge lamp (new edition)
Function of chopper in AAS
Modulate the light beam that would strike the sample cell that comes in flame
Photodetector for AAS
Photomultiplier tube
Application of AAS
To measure concentration of trace metals ( lead, mercury, cadmium)
Components of single-beam AAS
Light Source
Chopper
Sample
Monochromator
PM tube (Photomultiplier tube)
Readout/ Meter
AAS that does not require a burner to produce a flame but uses electric current
Flameless AAS
Method used to measure light emitted by excited atoms
Ion Selective Electrode
Application of ion selective electrode
To measure concentrations of sodium, potassium, and lithium
Measures the concentrations of solutions that contains fluorescing molecules
Fluorometry
Light source for fluorometry
Mercury (for filter fluorometers)
Xenon arc (for spectrofluorometers)
Fluorometer that use filter as monochromator (primary and secondary filter)
Filter fluorometers
Fluorometer that use prisms or gratings
Spectrofluorometers
Photodetector for fluorometry
Photomultiplier tube
Basic component of Filter fluorometer
Source
Attenuator
Primary filter
Sample holder
Secondary filter
Detector (PM)
Readout
Filters used in filter fluorometer and their function
Primary filter: selects wavelength of light that is best absorbed by sample
Secondary filter: passes the longer wavelength of light to photodetector
Advantages of fluorometry
Specific and sensitive
Disadvantage of fluorometry
Sensitive to environmental changes resulting to Quenching (decrease in fluorescence due to these changes)
Environmental changes causing quenching
Use of contaminated chemicals
Change in solvents
Use of UV light which causes photochemical changes
Change in temperature
The emission of light as a result of chemical reaction
Chemiluminescence
How does chemiluminescence differ from fluorescence?
No excitation radiation is required and no monochromators are needed
It is the production of electromagnetic radiation when a chemical reaction yields an excited product
Chemiluminescence
Advantages of chemiluminescence
Subpicomolar detection limits, speed, ease of use, and simple instrumentation
Disadvantage of chemiluminescence
Impurities can degrade sensitivity and specificity
Principle of turbidimetry and nephelometry
Based on the scattering of radiation by particles in suspension
Applications of turbidimetry and nephelometry
Measurement of antigen-antibody reactions, prealbumin, and other serum proteins
It is the measurement of the light scattered by a particulate solution
Nephelometry
3 types of light scatters
Rayleigh theory
Mie theory
Rayleigh-Debye theory
This theory states that when the wavelength of light is greater than the diameter of the particle, then there is symmetrical distribution of light scattering
Rayleigh theory
According to rayleigh theory, the minimum light scatter occurs at how many degrees to the incident light?
90 degrees
This theory states that if the wavelength of light < the particle diameter (d > 0.1 λ), then the light scatters forward
Mie theory
This theory states that if the wavelength of light is approximately the same as the particle size, more light scatters in the forward direction than in other direction
Rayleigh-Debye theory
Device used to measure a concentration of a solution using the analytical technique nephelometry
Nephelometer
Components of nephelometer
Light source
Collimator
Monochromator
Sample cuvette
Photodetector
Light source for nephelometer
Mercury-arc lamp
Tungsten- filament lamp
Light-emitting diode
Laser
Function of collimator
Narrows or control a beam of light
Determines the amount of light blocked by a suspension of particles
Turbidimetry
Applications of turbidimetry
It is used in microbiology analyzers, coagulation analyzers, and is used to quantify protein concentration in biologic fluids such as urine and CSF
What is the difference between nephelometry and turbidimetry?
Nephelometry detects (right-angle or forward) scattered light, and turbidimetry measures a reduction of light transmitted in the forward direction
Electrochemistry techniques
Potentiometry
Coulometry
Amperometry
Voltammetry
Involves the measurement of the current or voltage generated by the activity of specific ions
Electrochemistry
Most widely used technique in clinical measurements
Potentiometry
Measurement of potential (voltage) between two electrodes in a solution
Potentiometry
The two electrodes in potentiometry
Reference Electrode
Indicator Electrode
Electrode with a constant voltage
Reference Electrode
Most used reference electrode in the laboratory
Calomel and Silver/Silver chloride
Measuring electrode
Indicator Electrode/Analytical Electrode
Can be calculated from the measured potential difference between 2 electrodes
Concentration of Ions
Replaced the Flame Photometry
Ion-Selective Electrode
Membrane used to measure sodium
Glass aluminum silicate
Membrane used to measure potassium
Valinomycin Gel
Membrane used to measure calcium and lithium
Organic Liquid Ion Exchangers
Membrane used to measure carbon dioxide and ammonia
Gas Electrodes
Membrane used to measure urease and glucose oxidase
Enzyme Electrodes
Two type of ISE
Direct ISE
Indirect ISE
ISE that does not require sample dilution
Direct ISE
ISE that requires sample dilution before the analysis phase
Indirect ISE
Used to measure hydrogen ion (concentration) activity
pH electrode
Internal Reference Electrode
Silver/silver chloride
External Reference Electrode
Calomel electrode
A pH electrode within a plastic jacket (has sodium bicarbonate buffer and gas-permeable membrane)
pCO2
Measures the quantity of electricity (in coulombs) needed to convert an analyte to a different oxidation state
Coulometry
Applications of coulometry
To measure chloride ion in serum, plasma, CSF, and sweat samples
It is the measurement of the current flow produced by an oxidation-reduction reaction
Amperometry
Applications of amperometry
To measure chloride ion in serum, plasma, CSF, and sweat samples; pO2 electrode blood gas analyzers
Gas sensing electrode
pO2 Electrode
Application of pO2 electrode
To measure the partial pressure of oxygen in the blood
it is a method in which a potential (voltage) is applied to an electrochemical cell and the resulting current is measured
Voltammetry
Used to measure heavy metals such as lead
Anodic Stripping Voltammetry
Measurement of the number of dissolved particles in a fluid
Osmometry
Osmotically active particles
Glucose
Urea Nitrogen/ Blood Urea Nitrogen (BUN)
Sodium
Effects of increased osmolality
Osmotic pressure increases
Boiling point increases
Freezing point decreases
Vapor pressure decreases
Is used to measure the concentration of solute particles in a solution
Osmometer
The process of separating the charged constituents of a sample by means of an electric current
Electrophoresis
Electrophoresis is the separation of charged compounds based on their
Electrical charge
A substance that can either have a negative, zero or positive charge depending on the conditions
Amphotheric
Compounds that when dissolved in water can act either as acid or as a base
Ampholytes
Negatively charged ions
Anion
Positively charged ions
Cation
Ions that are neutral and have both positive and negative charges at different locations throughout the molecule
Zwitterions
Negatively charged electrode
Cathode
Positively charged electrode
Anode
Factors affecting the mobility of particles
Net charge of the particle
Size and shape of the particle
Strength of the electric field
Chemical and physical properties of the medium
Electrophoretic temperature
Migration of small ions
Iontophoresis
Migration of charged macromolecules in a porous support medium
Zone Electrophoresis
Components of electrophoresis
Power supply
Buffer
Support Medium
Sample
Detecting System
Function of power supply
Supplies constant current or voltage in the system
Known as the driving force in electrophoresis
Power supply
Why does the power supply named as the driving force in electrophoresis?
Because this drives the molecules through the support medium
Function of buffer
Provide ions that will enable the movement of current and migration of particles
Maintain the pH at a relatively constant value
A mixture of proton-donating and proton-accepting substances that functions to maintain the pH at a constant value
Buffer
Barbital (veronal) pH
8.6
Tris-boric EDTA pH
8.7
Cation migrates to the
Cathode
Anion migrates to the
Anode
pH will influence the charge of the analyte. True or False?
True
Relationship between ionic strength and mobility
LOW I.S = more charge will be carried = faster mobility
HIGH I.S = less charge will be carried = slower mobility
A network of interacting fibres or a polymer that is solid but traps large amount of solvent in its pores or channels inside
Support media
The support media must not interact with the analyte, it is just supposed to support the analyte to pass through it. True or False?
True
Examples of support media
Cellulose Acetate
Agarose Gel
Polyacrilamide Gel
Cellulose that is acetylated from cellulose acetate by treating it with acetic anhydride
Cellulose acetate
Cellulose acetate separates serum proteins into how many bands
5 bands
5 bands produced when using cellulose acetate
Albumin
Alpha-1
Alpha-2
Beta
Gamma
The support media of choice
Cellulose acetate
Useful in doing electrophoresis with proteins that can be separated with 5 bands
Isoelectric Focusing
Used as a purified fraction of agar that comes from red algae
Agarose gel
Unique features of agarose gel
It is neutral and does not produce electroendosmosis
Agarose gel separates proteins into how many bands?
10-15 bands
Support medium used to separate protein based on charge and molecular size
Polyacrilamide gel
Polyacrilamide gel separates serum proteins into how many bands?
20 or more bands
Result of electrophoresis consisting of separated strands of a macromolecule
Electrophoretogram
Detecting system that can already be conducted if the samples are already dyed or stained
Direct observation
The simplest way of detection in electrophoretic system
UV visualization
A device that measures the degree of darkness of a photographic or semitransparent material or of a reflecting surface
Densitometer
Examples of electrophoretic detecting system
Electrophoretogram
Direct observation
Staining
Radioactive dye
UV visualization
Densitometer
Applications of electrophoresis
DNA Fractionation
Isoenzyme Determination
Protein Fractionation
Process of forming electric cloud that prevents analytes or particles from migrating into the support medium
Electroendosmosis
Separation is determined through the speed of the analyte’s migration
Isoenzyme determination
Separate complex mixture on basis of different physical interactions between individual compound and stationary phase of the system
Chromatography
Basic components of chromatography and their functions
Mobile Phase: carries complex mixture
Stationary Phase: through which mobile phase flows
Column: holds the stationary phase
Eluate: separated component
Modes of separation in chromatography
Adsorption
Partition
Steric Exclusion
Ion exchange
2 classifications of chromatography based on stationary phase
Planar chromatography
Column chromatography
Classification of chromatography where the stationary phase is coated with a sheet of paper or bound to glass or plastic plate
Planar chromatography
Classification of chromatography where the stationary phase is packed into tube or coated onto the inner surface of the tube/column
Column chromatography
Examples of Planar chromatography
Paper chromatography
Examples of Column chromatography
Thin layer chromatography
Gas chromatography
Liquid chromatography
Application of Paper chromatography
Fractionation of sugar and amino acid
Application of Thin-Layer chromatography
Drug screening
Application of Gas chromatography
Separate mixture of compounds that are volatile made or can be made volatile
Application of Liquid chromatography
Uses pressure for fast separation of thermolabile substance
Why do we need to separate thermolabile substances immediately?
Thermolabile substances must be separated immediately, because when it is exposed to high temp. they will be destroyed and goes unstable that can cause us not to recover anything
How can we differentiate a gas chromatography to a liquid chromatography?
We can differentiate them based on their mobile phase
How can we differentiate planar and column chromatography?
We can differentiate them based on their stationary phase
Forces the mobile phase through the column
Pumps
Holds the stationary phase
Columns
Introduce the sample into the mobile phase
Sample injectors
Produce an electronic signal proportional to the concentration of separated component
Detectors
Most common photodetector used in spectrophotometer
Photomultiplier tube
Save the measurement of elutions
Recorders
Elution strength of the mobile phase is constant
Isocratic elution
2 distinct portion of mass spectrophotometer
Fragmentation
Ionization
Separate the components of a mixture
Fragmentation
Methods use to ionize samples
Electron Spray Ionization (ESI)
Matrix Assisted Laser Desorption Ionization (MALDI)
Analyzers used to measure mass-to-charge ratio
Quadrupole mass analyzers
Iron trap analyzers
Time of flight analyzer