2. CONTENT…
Introduction
Need for automation
Objective of automation
Advantages automatic analyses
Unit operations in chemical analysis
Types of automated analysis
Flow-injection analysis
Discrete automatic systems
Reference
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3. INTRODUCTION …
Automation is the performance of operations
without human intervention.
Automation may involve operation like the
preparation of samples, the measurements of
responses, and the calculation of results.
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4. NEED FOR AUTOMATION…
The partial or complete replacement of human
participation in laboratory process.
Increasingly stricter control of growing number of
samples in which a large number of analytes are to
be determined at increasingly low concentration.
Cost reduction.
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5. OBJECTIVE OF AUTOMATION…
Automation is used for :
Facilitating an analytical method or technique
Processing of large number samples
Determination of several components in the same
sample
Reduction of human participation
To avoid error
Process ( industrial or otherwise ) control
Lowering consumption of sample and/or reagents
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6. Analytes , which are sometimes present in very
low concentration in sample
Reagents , some of which are rare or expensive,
even unstable
Rapidity
Economy , in personnel and material expenditure
Precision, closely related to the elimination of
both definite and indefinite errors arising from
human factors
Data generation
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7. ADVANTAGES OF AUTOMATIC
ANALYSES…
Automated instruments offer a major economic
advantage because of their savings in labor costs.
Their speed, which is frequently significantly
greater than that of manual devices. So, the number
of determination per day can be much higher than
with manual methods.
A well-designed analyzer can usually produce
more reproducible results over a long period of
time than can an operator employing a manual
instrument.
The ability to process samples in situation that
7 would be dangerous for humans.
8. UNIT OPERATIONS IN CHEMICAL
ANALYSIS...
All analytical methods can be broken down into a
series of eight steps, or unit operations, any one of
or more can be automated.
The next table lists the steps in the order in which
they occur in a typical analysis.
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9. TYPES OF AUTOMATED
ANALYSIS…
Automatic analytical systems are of two general
types:
1) Discrete analyzers
2) Continuous-flow analyzers
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10. 1) Discrete analyzers…
In this , individual samples are maintained as
separate entities and kept in separate vessels
throughout each unit operation.
The system has many moving parts.
Ex. Discrete automatic analyzer
Advantage:
Cross contamination among samples is totally
eliminated.
Inexpensive and reliable
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11. 2) Continuous-flow analyzers..
In this , the sample becomes a part of a flowing
stream where several of the steps take place.
Ex. Flow injection analysis
Here, interaction among samples are always
concern. So, special precaution are required to
minimize sample contamination.
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12. FLOW-INJECTION ANALYSIS...
Flow-injection methods are an outgrowth of
segmented-flow procedures, which were widely
used in clinical laboratories in the 1960s and 1970s
for automatic routine determination of a variety of
species in blood and urine samples for medical
diagnostic purposes.
In segmented-flow system , samples were carried
through the system to a detector by flowing
aqueous solution.
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13. Instrumentation...
In this, a peristaltic pump moves colorimetric
reagent directly into a valve that permits injection of
samples into the flowing stream.
The sample and reagent then pass through a 50 cm
reactor coil where the reagent diffuses into the
sample plug and produces a colored product by
sequence of reactions.
From the reactor coil, the solution passes into a flow-
through photometer and the signal output from this
13 system for a series of standards .
14. Sample and reagent transport
system...
Ordinarily, the solution in a flow-injection analysis
is moved through the system by a peristaltic pump,
a device in which a fluid (liquid or gas) is
squeezed through plastic tubing by rollers.
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15. Sample injectors and
detectors...
The injectors and detectors employed in flow-
injection analysis are similar in kind and
performance requirements to those used in HPLC.
Sample size for flow injection procedure ranges
from 1μL to 200 μL.
For successful analysis, injectors must not disturb
the flow of the carrier system.
The most common detectors in flow injection are
spectrophotometer, photometer and fluorometer.
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16. Separations in FIA...
Separations by dialysis, by liquid/liquid extraction,
and by gaseous diffusion are readily carried out
automatically with flow-injection systems.
1. Dialysis and gas diffusion
2. Extraction
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17. 1) Dialysis and gas diffusion...
Dialysis is often used in continuous-flow methods
to separate inorganic ions, such as chloride or
sodium or small organic molecules, such as
glucose, from high-molecular-weight species such
as proteins.
It is used for determination of ions and small
molecules in whole blood stream or serum.
Gas diffusion from a donor stream containing a
gaseous analyte to an acceptor stream containing
reagent that permits its determination.
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18. 2)Extraction...
Another common separation technique readily
adapted to continuous-flow methods is extraction.
Ex. A system for the colorimetric determination of
an inorganic cation by extracting an aqueous
solution of the sample with chloroform containing
a complexing agent such as 8-hydroxyquinoline.
It is important to reiterate that none of the
separation procedures in FIA methods are
complete.
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19. analysis...
After injection with a sampling valve, it moves
through tubing, so band broadening or dispersion
takes place.
In this, convection arising from laminar flow and
creating a parabolic front and skewed zone profile.
Diffusion also causes band broadening. Two types
of diffusion occur: radial (perpendicular the flow
direction) and longitudinal(parallel to the flow
direction).
At low flow rate, radial diffusion is the major
source of dispersion.
So, dispersion by both convection and radial
19 diffusion occur.
20. Dispersion...
Dispersion D is defined by the equation
D = co/c
where ,
co = analyte concentration of the injected
sample and c = peak concentration at the detector.
Dispersion is influenced by three interrelated and
controllable variables: sample volume, tube length,
and pumping rate.
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21. Applications of flow-injection
analysis…
In the flow-injection literature, the terms limited
dispersion, medium dispersion, and large
dispersion are frequently encountered where they
refer to dispersions of 1 to 3, 3 to 10, and greater
than 10, respectively.
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22. 1) Limited-dispersion applications:
Limited-dispersion flow-injection techniques have
found considerable application for high-speed
feeding of such detector systems as flame atomic
absorption and emission as well as inductively
coupled plasma .
2)stopped flow methods:
It is used for kinetic measurement.
3)flow injection titration:
Titration can also be performed continuously in a
flow injection apparatus.
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23. DISCRETE AUTOMATIC
SYSTEMS...
A wide variety of discrete automatic systems are
offered by numerous instrument manufacturers.
Some of these devices are designed to perform one
or more unit operation.
For ex. Determination of nitrogen in organic
compounds or determination of glucose in blood.
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24. Automatic sampling and sample
definition of liquids and gases...
This device consists of a movable probe, which is
a syringe needle or a piece of fine plastic tubing
supported by an arm that periodically lifts the tip
of the needle or tube form the sample container
and positions it over a second container in which
the analysis is performed.
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25. Robotics...
The robotic system is controlled by a
microprocessor that can be instructed to bring
samples to the master laboratory station where they
can be diluted, filtered, partitioned, ground,
centrifuged, extracted, and treated with reagents.
For general purpose laboratory robots, robotics
units are designed for specific tasks such as
loading and unloading of microtiter.
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26. REFERENCE
Skoog D.A. , “Instrumental Analysis” , second
edition, New Delhi, 1015
Gary D. Christian, “Analytical Chemistry”, 6th edn,
page no 660.
Hobart H. Willard, Lynne L. Merrit, “Instrumental
Methods of Analysis”, 7th edn, page no- 786.
N. Gray, M. Calvin, S C Bhatia, “Instrumental
Methods of Analysis”, page no-27
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