Transcript Biochemical instrumental analysis-3

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.
Definition
 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.
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.
4 decrease
2 increase
1 funny
I-Continuous flow analysers
In 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.
II-Discrete analyzers
 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.
 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
How it work?
 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.
 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
absorbance.
measures
the
resultant
 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.