biochemical instrumental analysis-14
DESCRIPTION
AutomationTRANSCRIPT
Biochemical instrumental analysis-14 Dr. Maha Al-Sedik
Automation
During the past few year, there has been a
considerable increase in clinical demand for
laboratory investigations.
When the volume of work increased, there must be a
need for work simplification.
Laboratory automation: is the use of instrument and
specimen processing equipment to perform clinical
assay with only minimal involvement of the
technologist.
Another definition is mechanization of the laboratory
work.
Definition
Sure
Decrease human error. Decrease liability to infection. Decrease laboratory costs. Decrease time needed for the test. increase productivity. Increase number of tests for the same sample. Employ relatively less skilled laboratory technician.
Why automation?
4 decrease2 increase
1 funny
I-Continuous flow analysersIn these systems, the samples and reagents are passed sequentially through the same analytical pathway and separated by means of air bubbles.
Samples were aspirated into tubing to
introduce samples into a sample holder.
Bring in reagent.
Create a chemical reaction.
Pump the chromogen solution into incubator
then cuvette for spectrophotometric analysis.
Principle of detection: Detection is by measuring absorbance by
spectrophotometer through a continuous flow
cuvette (cell) at a certain wavelength.
When there is no sample, the sample probe is placed
in distilled water to avoid blockages, clogging and
precipitation.
Disadvantages:
1-The machine does not allow test selection, all tests
must be performed even if not requested.
2-The machine must run continuously even when there
are no tests.
3-Because of the continuous flow, reagents must be
drawn at all times even when there are no tests to
perform.
4-The instrument must be closely monitored all the
time for air bubbles uniformity; reagent availability
and tubing integrity and most important of all carry
over problems.
5-They are usually large in size and occupy large
space.
Discrete analysis is the separation of each sample and
accompanying reagents in a separate container.
Discrete analyzers have the capability of running
multiple tests on one sample at a time or multiple
samples one test at a time.
They are the most popular and versatile analyzers and
have almost completely replaced continuous flow.
II-Discrete analyzers
Sample reactions are kept discrete (separated) through the use of separate reaction cuvettes, cells, slides, or wells that are disposed of following chemical analysis.
This keeps sample and reaction carryover to a minimum but increases the cost per test due to disposable products.
Hitachi 902 Analyzer
The Operator selects the test(s) he would like to run and enters the Sample IDs and any other information for the analysis.
Sample test tubes and reagent bottles are loaded onto the system.
The run is started.
How it work?
The system uses its robotic arm, sample needle and syringe to mix samples and reagents in the reaction cuvettes.
Once the end point of the reaction is completed, the photometer measures the resultant absorbance.
The data is collected by the software.
The data can be printed. Discrete analyzers have the capability to run multiple
tests one sample at a time or multiple samples one
test at a time.
They are the most common analyzers.
Discrete analyzer
Batch analysers
Stat analysers
(A) Batch analysers: These are convenient to analyse specimen in
batches
( groups ) such as of sugar, urea or creatinine etc.
state testing may not be conveniently carried out on
these analysers.
The batch analysers can be further differentiated as
(1)semi automated.
(2)fully automated.
(B) Stat Analysers: In the case of these analysers many reagents (8 to
20 or more) can be pipetted one after another, so
that various biochemical determinations can be
performed on one specimen, according to the
number of tests ordered for the patient.
Each sample is treated differently according to the
tests requested and programmed by the operator. E.g.
Sample 1 glucose, urea, creatinine and electrolytes.
Sample 2 total protein, albumin, calcium.
Sample 3 triglycerides, cholesterol.
Sample 4 bilirubin, ALT, AST, ALP.
III-Centrifugal Analyzer Samples and reagents are added in a specially
designed centrifugal type cuvette that has three main
compartments.
Sample is added from the sample cup by auto-sampler
into the sample compartment of the centrifugal
cuvette.
The reagent probe into the reagent compartment of
the centrifugal cuvette adds Reagent.
Both sample and reagents are allowed to equilibrate
to the reaction temperature.
Mixing of sample and reagent occurs when the rotor
holding the cuvette is spun at high speed (4000 rpm)
and then sudden stop.
The spinning causes the sample to be added to the
reagent while the turbulence caused by sudden stop
results in mixing of sample and reagent.
After mixing, the rotor is spun at 1000 rpm. The
reaction mixture is pushed horizontally to the
bottom of the cuvette.
Principle of detection:
It has clear transparent sides for spectrophotometric
measurement.
Advantages:
Rapid test performance analyzing multiple samples.
Batch analysis is a major advantage because
reactions in all cuvettes are read simultaneously.