This ppt describes the auto analyser which is used in biochemistry department in hospitals for analysing the composition of various constituents in the blood and other body fluids.

1. AUTO ANALYSER
By,
A. Michael nickson
BIOMEDICAL INSTRUMENTTION

2.  An Auto analyzer is used for clinical analysis (e.g.
to measure blood chemistry) and display that on a
graphic recorder.
 It was invented in 1957 by Leonard Skeggs and
commercialized by Jack Whitehead’s Technicon
Corporation
 It works on the principle of Continuous flow
analysis (CFA) which comprises of both
segmented flow analysis (SFA) and flow injection
analysis (FIA)
AUTO ANALYSER:

3.  The basic principle of the SFA is the introduction of air bubbles.
 In SFA a continuous stream of material is divided by air bubbles
into discrete segments and reagents are combined and
transported in tubing and mixing coils.
 The tubing passes the samples from one apparatus to the other
with each apparatus performing different functions, such as
distillation, dialysis, extraction, ion exchange, heating,
incubation, and subsequent recording of a signal. An essential
principle of SFA is the introduction of air bubbles.
 The act as a barrier between packets to prevent cross
contamination as they travel down the length of the glass tubing.
Segmented Flow Analysis (SFA):

4. Flow Injection Analysis (FIA):
 SFA uses air segmentation to separate a flowing
stream into numerous discrete segments to
establish a long train of individual samples moving
through a flow channel while FIA systems separate
each sample from subsequent sample with a carrier
reagent.
 In all FIA techniques sample and reagents are
merged to form a concentration gradient that yields
analysis results.

5. COMPONENTS :
 Sampler
 Proportioning pump
 Dialyzer
 Heating bath
 Colorimeter
 Graphic recorder

6. SAMPLER:
 This module holds the batch of samples awaiting analysis in
separate cups on a circular tray which is rotated at intervals.
 A probe connected by plastic tubing to the proportionating pump
enters each sample serially.
 The volume of sample aspirated is determined by the pumping
rate and the adjustable dwell time of the probe in the sample.

7. PROPOTIONING PUMP:
 This module determines the relative flow rates of sample and all
reagents and replaces the use of different sizes of pipettes in manual
methods.
 The pumping technique involves the peristaltic action produced by a
series of rollers passing along an array of parallel plastic “Pump
tubes”.
 Each roller compresses all tubes so that the rate flow in each tube is
proportional to the square of the pump tube diameter.

8. DIALYSER:
 This module achieves the separation of small and large molecules
by allowing the former to pass through a semipermeable
membrane from the donor (sample) stream of liquid and air
bubbles to a recipient , stream of liquid again segmented by air
bubbles.
 The dialysis rate depends on the temperature but complete
passage of small molecules into the recipient stream is rarely
achieved and may be only a few percent of the total.

9. HEATING BATH:
 It is to maintain the reaction mixture at a constant temperature for a
defined time to bring about the required chemical change under controlled
conditions.
 The incubator bath consists of a glass delay coil mounted in a
thermostatically controlled oil bath. This is sealed and stirred constantly.
 Most baths are set at 37°C or 95°C but some have adjustable thermo-
regulators which allow operation up to 120°C or even higher.

10. COLORIMETER:
 The colorimeter is to measure the intensity of colour produced in
the reaction and to provide a graphical display of change in
colour with time.
 The use of double beam spectrophotometer is costly and is rarely
justified by analytical requirements. The single beam colorimeters
have insufficient stability to operate reliably over the long period
required.
 The Auto-analyser MKI colorimeter combines double beam
operation with interference filters to select the wavelength.

11. RECORDER:
 Previously a chart recorder and more recently a data
logger or personal computer records the detector output
as a function of time so that each sample output
appears as a peak whose height depends on the
analyte level in the sample.