Notesale: Turn your study into money

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PRINCIPLES OF INSTRUMENTATION AND ANALYTICAL
METHODS

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SAMPLE CELL/CUVETTE
Where to place the sample

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OUTPUT DEVICE
Displays absorbance

LIGHT
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Consists of photons or packets of energy travelling in
waves

WAVELENGTH
Distance between successive waves between two
peaks
Measured in nanometer

BLANICING
Calibration using distilled water

COLORS AND COMPLEMENTARY COLOR OF THE VISIBLE
SPECTRUM
WAVELENGTH
COLOR ABSORBED
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ATOMIC EMISSION SPECTROPHOTOMETRY (Flame
Photometry)
PRINCIPLE:
 Involves measurement of electromagnetic
radiation emitted by the excited atoms in flame
FLAME:
 Reducing gases in the flame
 Metal ions – neutral atoms
 Provides thermal energy
 Ground state – excited state

BEER-LAMBERT LAW
States that the concentration of a substance is
directly proportional to the amount of light
absorbed
Inversely proportional to the logarithm of
transmitted light
A = abc = log(100% / T) A = 2 – log%T

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LIGHT SOURCE
 Tungsten Bulb – visible light
 Deuterium/H2 Lam – UV light
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VOLUMETRIC IMPEDANCE
For cell size
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REFERENCE ELECTRODES
Produces constant potential

HIGH-FREQUENCY ELECTROMAGNETIC ENERGY
For nuclear constituents

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ABOTT CELL-DYN
Integrate the impedance method and flow
cytometry method
Accurately measure WBC
PENTRA

VOLTAMETRIC METHODS (3 electrodes)
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REFERENCE
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POTENTIOMETRY
The most widely used clinical application of
electrochemistry and involves the measurement of a
cell potential (voltage) under equilibrium conditions

AMPEROMETRY
A controlled-potential technique in which current is
measured at a fixed applied potential
Uses the enzyme glucose oxidase, immobilized
between two membranes

COULOMETRY
Is an electrochemical titration in which the titrant is
electrochemically generated and the endpoint is
detected by amperometry

Glucose oxidase
GLUCOSE ------ Gluconic Acid + Hydrogen Peroxide
ELECTROPHOTORESIS
The movement of charged particles because of an
external electric field

AMPEROMETRY
The measurement of the electrical current at single
applied potential
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solution under the condition of essentially zero
current
The measured potential is related to the molar
concentration by the Nernst equation

ELECTRODES:
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ANODE – positively charged

VOLTAMETRY
Used to measure solution composition based on the
current-potential relationship in an electrochemical
cell when the potential is applied

Thus;
Cations (+) ------------> Cathode (-)
Anions (-) -------------> Anode (+)

POTENTIOMETRIC METHODS
Based on the measurement of a potential or voltage
difference between two electrodes immersed in

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2 TYPES
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DRIVING FORCE (Electrical Power)
Supplies constant current

BUFFER
Acid or base ----- isoelectric point

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MASS SPECTROMETRY
Used on fragmentation and ionization of molecules
using a suitable source of energy
Charged particles moving through a magnetic or an
electrical field can be separated from other charged
particles according to their mass-to-charge (m/z)
ratios

SUPPORT MEDIUM
Holds sample in place for migration

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Adsorption
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Steric Exclusion
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COLUMN
Holding the stationary phase

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ZONE ELECTROPHOTORESIS
Migration of charged macromolecules in a porous
support medium such as paper, cellulose acetate, or
agarose-gel

Carries the complex mixture

DETECTING SYSTEM/QUANTIFICATION
Visualization under UV light, stains and densitometer

Resulting ion
Specific molecular mass and charge
Mass spectrometer
Intensity of each ion
DENSITOMETER
PRINCIPLE:
 Measures absorbance of the stain on a support
medium

Number of Ion reaching the detector

CLINICAL LABORATORY AUTOMATION

COMPONENTS:
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Monochromator
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Optical System
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CHROMATOGRAPHY
Refers to a group of techniques used to separate
complex substances on the basis of different physical
interactions between the individual compounds and
the stationary phase of the system

Reduction of costs
Expansion of lab testing to generate more revenue
Reduction of turnaround time
Reduction of lab errors
Improvement of lab safety

TYPES OF LAB AUTOMATION:
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MOBILE PHASE
Liquid or gas

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Cost saving ====== reduction in labor
Requires larger space in the hospital
Needs on-site engineers and supervisors

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STAND-ALONE SYSTEMS
To automate specific sections of the process that are
still manual operations
Include specimen processing and sample archiving

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CONTINOUS-FLOW ANALYZERS
The samples flow through a common reaction vessel
or pathway
DISCRETE ANALYZERS
The samples travel through the instrument in its own
reaction vessel

DESIGNS OF THE ANALYZER PATHWAY
 Sequential
 Batch
 Parallel
 Random Access
SEQUENTIAL TESTING
Multiple tests analyzed one after another on a given
specimen

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MANUAL STEPS AUTOMATED
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Measuring and adding reagents
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Incubating the sample mixture
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Measuring and reading the sample reaction

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DWELL TIME
Is the minimum time required to obtain a result after
the initial sampling of the specimen

SPECIMEN PROCESSING
Samples are sorted, centrifuged, uncapped, and
divided into aliquots if tests for more than one
workstation have been requested

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