J. Green
Why do we need Good results?
Chemical Industry
• Purpose: To produce chemicals.....
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to the correct specification
profitably
without harm to the environment
safely
lawfully
whilst protecting intellectual property
Analytical Chemistry has its part to play.....
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
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Why do we need Good results?
Good Results
• Fit for purpose
• Provided on time
• Accurate
• Obtained at minimum
cost & effort
• Retrievable /Traceable
• Precise
• Qualitative / Quantitative
• Consistent
• Allow decisions to be made
• Provided in an appropriate
form
• Validated
• Repeatable
• Reproducible
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
J. Green
Why do we need Good results?
Industrial Functions
• Manufacture
• Research & Development
• Supplying the customer
• Health Safety and Environment
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
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Why do we need Good results?
Industrial Research
(Example)
Example - conversion of butane into ethene
• Possible dehydrogenation reaction
butane
ethene + propene + butene
• Important parameters:
– Conversion of butane into products
– Selectivity of conversion to ethene
• Analytical requirements
– accuracy  to ensure scale-up is valid
– sensitivity  to detect low concentrations
– flexibility  to identify unexpected products
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
J. Green
Why do we need Good results?
Chemical Manufacture
Analytical Requirements
• precision of measurement
– monitors progress of reaction
– detects process fluctuations
• accuracy less important
• frequency of analysis
• minimum cost & effort
• display of results/feedback protocols
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
Why do we need Good results?
Supplying the Customer
• Accuracy
ensures product is ‘in-spec’
• Demonstrate validity
a recognised method
• Reproducibility
comparable result whoever carries out
the analysis
• Consistent
same sample same result
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
Why do we need Good results?
Analytical Techniques & Product Purity
• High purity is expensive
– More steps required in fractional crystallisation
– Less take-off in distillation columns
• Better analytical techniques reduce the cost of
obtaining high purity
– Greater precision allows required purity to be
targeted more closely
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
Why do we need Good results?
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Analytical Confidence Limits
• All measurements have errors associated with them
• Quoted values should therefore be expressed with an
associated confidence interval [X ± x units]
• To be assured that a sample conforms to a quoted
specification limit an analytical value must be obtained for
the sample that takes the confidence interval into account.
Example:
• Technique gives value ± 1%
• Sample must be >97% pure
• Therefore technique must deliver a value of 98% to be
confident of sample purity being >97% pure
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
J. Green
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Why do we need Good results?
Analytical Techniques & Cost of Quality
Cost
98.1%
95%
96%
97%
98%
99%
98.5%
Purity (%)
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
100%
J. Green
Why do we need Good results?
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Analytical Techniques and Asset Utilisation
• Chemical plant is expensive
• Maximum utilisation is desirable
• Analytical techniques help to maximise the
utilisation
– Reduce turnround times on batch operations
– Increase throughput on continuous plant
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
J. Green
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Why do we need Good results?
Analytical Techniques and Asset Utilisation
Batch Operations
Times at which batch can be terminated
for required conversion
Reactant
Concentration
Conversion
Required
Analytical technique 2
Improved
0
1
Analytical technique 1
2
Time of Batch Operation
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
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Why do we need Good results?
Analytical Techniques & Asset Utilisation
Continuous Processes
Analytical technique
2
Throughput
Analytical technique 1
Required
Purity
96%
97%
98%
Purity of product required
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
99%
J. Green
Why do we need Good results?
Analytical Chemistry &
Environmental Responsibilities
• Emissions to Air
• Emissions to Water
• Waste disposal - off-site
• Technical challenges
– low concentrations in air/water/solids
– sample collection times
– sensitive techniques required for temporal resolution
– samples containing contaminants
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
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J. Green
Why do we need Good results?
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Corrosion Measurements
• Chemical Plant Maintenance
– Regular shutdowns / unplanned shutdowns
– Components replaced
• Corrosion /Production /Shutdown Frequency
– Relationship between corrosion & process variables .....
– higher productivity whilst maintaining plant integrity
– lower frequency of shutdowns
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000
J. Green
Why do we need Good results?
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Valid Analytical Measurement Principles
• Analytical Measurements should be made to satisfy an agreed objective
• Analytical Methods should be made using methods and equipment which
have been tested to ensure they are fit for purpose
• Staff making analytical measurements should be both qualified and
competent to undertake the task
• There should be regular independent assessment of the technical
performance of a laboratory
• Analytical measurements made in one location should be consistent with
those made elsewhere
• Organisations making analytical measurements should have well defined
quality control and quality assurance procedures.
B. Neidhart, W. Wegscheider (Eds.): Quality in Chemical Measurements © Springer-Verlag Berlin Heidelberg 2000