Automating Wet Chemical Analysis
William Lipps Market Specialist for Water Analyzer Products
December 11, 2008
The advantages of automating wet
chemical analysis.
• Save time
• Decrease cost
• Improve quality
• Reduce waste
• Do more samples
• Do more samples
• Do more samples
The benefits of automating wet
chemical analysis
The economic advantage of
automation is greater throughput.
More Samples = More Money
“Silent Hours” – 3X Throughput
The simplest forms of automation are
now common laboratory tools.
• Magnetic stirrer
• Auto filling burettes
• Vacuum filtration
• Bottle top dispensers
Almost any chemistry can be
automated.
• Alkalinity
• Ammonia
• Chloride
• Nitrate
• Nitrite
• Nitrogen, Total
Kjeldahl (TKN)
• Phenolics
• ortho-
Phosphate
• Total
Phosphorus
• Silica
• Sulfide
• Sulfate
Automate the labor intensive
extractions and digestions.
• Digestion
• Distillation
• Solvent extraction
• Gas diffusion
• Dialysis
Make your life easier by automating
time consuming, manual methods.
Detector
Automated methods should be easy
and obtain better results.
• “easy-to-use”
• Better results
• Lower cost per test
Potential profit and cost savings is
high.
CATC OIA 1677
Wage $15 $15
Labor hours 4 1
Labor + OH $150 $37.5
Capacity (day) 10 480
Per Test Price $25 $25
Potential Profit $100 $ 10, 360
Two important questions to answer
before choosing an analyzer.
• Will I have a lot of samples for the
same tests?
• Or, will I have a lot of tests for a few
samples?
Two important automated chemistry
technologies.
Automated Wet Chemistry
SFA FIA Discrete
Continuous Flow Robotic
Continuous flow analyzers move liquid
continuously through tubing.
• Continuous flowing stream
• Mixing coils
• Detector
Segmented Flow Analysis minimizes
dispersion with air bubbles.
• Original Automated Analyzer
• Approved in regulatory test methods
The air bubbles minimize carryover
from one segment to the next.
The air segments ensure mixing and
maximum color formation.
The limited dispersion results in
rectangular peaks with flat tops.
Summation of Multiple Segments
A real example of segmented flow
peaks
Segmented flow limits dispersion
and enables steady state reactions.
• Low MDL
• Excellent Precision
• Steady state reactions
• Limited dispersion
• High throughput
• Easily expandable
Flow injection analysis injects sample
into an unsegmented stream.
Flow injection does not segment with
air and sample mixes by dispersion.
The FIA peak is shaped like a bell
curve.
Example of real FIA peaks
Flow injection analysis has high
throughput and is easy to use.
• High throughput
• Excellent Precision
• Ease of use
• No de-bubbling
• Rapid startup and shutdown
Segmented flow peaks reach
steady state and maximum color
SFA allows longer reactions for greater
color; FIA has greater throughput.
SFA FIA
Sample intro time loop
Volume ~200 µL ~200 µL
Max delay
time
10 minutes 1 - 2
minutes
Sample/hour 40 - 90 30 - 120
RSD < 2% < 2%
Reagent
(mL)
2 - 3 2 - 4
* OI Analytical FS 3100
Use Continuous Flow Analysis (CFA)
when you have a lot of samples to run.
• Choose CFA when automating a lot
of samples for a few tests!
• Exception – CNSolution
– No distillation makes CN analysis
economical regardless of sample
load
What is a Discrete Analyzer?
• Reactions in individual cuvettes
• Mixing within the cuvette
• Measurement within the cuvette
A discrete analyzer is a multi-
chemistry analyzer
• Batch Selective Analysis
• True Random Access
• Automatic Method Interchange
• “Hands off” operation
A discrete analyzer simplifies
automated chemistry.
A discrete analyzer uses cuvettes
instead of pump tubes
• Sample dispensed into cuvette
• Sample is blanked
• Reagents added to sample
• Sample incubates in cuvette
• Instrument measures absorbance
• Result calculated
The cuvette contains each individual
reaction.
• No peaks – single absorbance
reading
• No interaction between samples
• Equilibrium reactions (maximum
color)
Startup is easy because there are
no pump tubes or flows
• Reduces Turn-Around-Time
• Unattended Operation
• Only runs requested tests
• Standards Prepared Automatically
• Automatically Dilutes over-range samples
• No pump tubes
Use discrete analyzers for widely
differing matrices and daily routines.
• Choose discrete when automating a
few samples for a lot of tests.
• Choose a discrete analyzer when
running a variety of matrices, or
parameters.
CFA methods are faster than discrete
methods.
Discrete CFA
Reagents per test Continuously
flowing
Carryover None Need wash
solution
Throughput Function of #
reagents
Determined by
peak width
Discrete analyzers can run any method
without operator intervention.
Discrete CFA
Sensitivity Standard
Detector
ER Detector
# Tests per
run
Limited by
programming
Limited by #
detectors
Fluid System Disposable
cuvettes
Pump tubes
Discrete analyzers require almost no
maintenance
Discrete CFA
Operator
maintenance
Limited Change
pump tubes
Initial setup
per test
none 5 – 10
minutes
Final
teardown
per test
none 5 – 10
minutes
OI Automated Analyzers cover all
needs
FS IV FS3100 DA3500
Mode Continuous
or batch
Continuous
or batch
Batch
Selective no no yes
Random no no yes
Fast yes yes no
Choose an automated chemistry based
on your needs
• The technique to use depends on:
– Sample load
– Tests per sample
– Analytical Requirements (MDL,
etc)
• Make educated choice on what is
best for your application
For Additional Information
Questions and Comments?
Please visit our website at:
www.oico.com