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
The benefits of automating wet chemical analysis
• Do more samples • Do more samples • Do more samples
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 • Phenolics • Ammonia • ortho- • Chloride Phosphate • Nitrate • Total • Nitrite Phosphorus • Nitrogen, Total • Silica Kjeldahl (TKN) • 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
Continuous Flow Robotic
SFA FIA Discrete 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 10 minutes 1 - 2 time minutes Sample/hour 40 - 90 30 - 120 RSD < 2% < 2% Reagent 2 - 3 2 - 4 (mL) * 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 # Determined by reagents peak width Discrete analyzers can run any method without operator intervention.
Discrete CFA Sensitivity Standard ER Detector Detector
# Tests per Limited by Limited by # run programming detectors
Fluid System Disposable Pump tubes cuvettes Discrete analyzers require almost no maintenance
Discrete CFA Operator Limited Change maintenance pump tubes
Initial setup none 5 – 10 per test minutes
Final none 5 – 10 teardown minutes per test OI Automated Analyzers cover all needs
FS IV FS3100 DA3500 Mode Continuous Continuous Batch or batch or 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
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