ASPAC | Pacific network of soil laboratories: 1st meeting. Brisbane, Australia, 17 - 18 October 2019. Presenter: Roger Hill

1. Quality Assurance and Quality Control,
Uncertainty of Measurement,
and
Introducing ASPAC’s Inter-Laboratory
Proficiency Programmes (ILPP’s)
Roger Hill
Brisbane
17 October, 2019

2. Our Company
New Zealand’s largest privately
owned testing laboratory
• Started 1984 by Roger and
Anne Hill
• Three market sectors serviced
 Agriculture (30%)
 Environmental (50%)
 Food & Bio-analytical (20%)
• Now employ 430 staff
• 100% owned by staff working
there

3. Quality Assurance, Quality
Control and Laboratory
Accreditation

4. Quality Definitions
• The Quality Management System (QMS) is
the over-arching system that a laboratory (or
other business) puts in place.
• Quality Assurance (QA) is the planned and
systematic implementation of that QMS.
• Quality Control (QC) checks the lab methods
are performing as expected.

5. Quality Management System
• The QMS is usually documented in the
Laboratory Quality Manual
• Includes having documentation and processes
for:
- Staff training and management
- Clear documentation and document control
- Regular calibration and maintenance of all equipment
- Procedures for handling non-conforming work
- Regularly scheduled audits
- Use of QC checks with every batch of samples
- Having a formal Quality Policy statement

6. Quality Assurance
• This is the implementation of the QMS as
described in the Quality Manual.
• QA is in effect the umbrella under which QC
sits.
• “All staff have an important role to play in
the successful adoption of Quality
Assurance.”

7. What is Laboratory Accreditation?
• Laboratory accreditation provides an assurance to
customers that the laboratory has good quality
management systems in place.
• International Organisation for Standardisation (ISO) is
the most widely recognised entity for laboratory
accreditation.
• ISO publish Guides against which organisations are
audited. If compliant, accreditation will be granted.
• ISO/IEC Guide 17025: “General requirements for the
competence of testing and calibration laboratories”.

8. Quality Control at
Hill Laboratories

9. Quality Control
• QC is applied to the specific tests performed by the
laboratory, on an ongoing basis.
• QC tools used in agricultural testing at Hill
Laboratories are:
– Run blanks
– In-house QC samples
– Replicate analyses
– Certified Reference Materials (CRM’s)
– Inter-laboratory Comparison Programmes
(ILCP’s)
– Sample Exchanges

10. Run Blanks
• These are taken through the whole
process, but without a sample included.
• Detects contamination in reagents:
– If constant and very small, may be corrected for.
– If variable, suggests random contamination.
• Include at least two blanks. Often at the
start of the batch.

11. In-house QC samples
• Bulk samples usually prepared in-house
– From relatively uniform sampling area
– Thoroughly mixed
– Packed in manageable containers (e.g.500 mL)
– Establish Warning and Control Limits
• Run with every batch of samples.
• Normally, two different QC samples per
batch.
• Monitoring long-term stability.

12. Replicate analyses
• Provide an ongoing indication of analytical
precision (random error).
– Intra-batch, inter-batch
• Useful in quantifying analytical variability.
• Precision can be calculated using pairs of
data.
– Need to realise just what is included and what
is not.

13. Reference Materials (RM’s)
• May or may not be Certified. Certified means
it is traceable back to primary standards.
• Sourced from an external provider.
• Come with stated Consensus or Certified
analyte levels, usually with Uncertainty
Limits.
• An excellent external check on the laboratory
performance (accuracy).

14. Inter-Laboratory Proficiency
Programs (ILPP’s)
• Bulk Sample(s) are prepared, split into
multiple fractions, and sent to participating
labs to analyse.
• Each lab submits their results back to the
provider, who then statistically analyses the
dataset, identifying outliers and stragglers.
• Results sent back to each participant, who
can then see how they performed relative to
the other participants.

15. Sample Exchanges
• A ‘mini’ ILCP.
• Often quite informal.
• Two or more labs exchange samples and
compare results.
• Does not have the reassurance of a larger
number of labs participating, or the value of a
statistical evaluation.
• Still very useful.

16. The ‘External Check’
• Very important to have an external
check.
• Not until you do check yourself against
other laboratories can you be sure that
you are getting the right answer.
• By using either CRM’s, ILCP’s or Sample
Exchanges.

17. Questions?

18. Uncertainty of Measurement

19. Uncertainty of Measurement
(UoM)
• A very interesting and important subject. As
practicing analysts, we should understand this.
• For me personally, I have found it gives a deeper
understanding of what we are doing
• Enables us to answer the question, is the method
and result ‘fit for purpose’?
• ISO Guide 17025 states we must be able to provide
UoM data in circumstances where it may be critical.

20. Expressing UoM
UoM usually expressed
as the standard
deviation, or Co-
efficient of Variation.
Sometimes Expanded
UoM. Usually x2,
which for normally
distributed data,
corresponds to the 95%
Confidence Limit.

21. Determining UoM
• ‘Bottom Up’ approach
- Preferred by ISO
- Also called Uncertainty Budget
- ‘Fishbone’ approach
• ‘Top Down’ approach
- Uses real data, e.g. from QC samples
- Need to understand just what is covered
• Combination best

22. Simple Fishbone for soil test

23. Significant sources of uncertainty
for Olsen P

24. Significant sources of
uncertainty for extractable K

25. Variation covered by in-house
QC sample for ext K

26. In Summary….
• Understanding UoM is important to
improve your service, and to ensure
the tests are ‘fit for purpose’.
• It makes you a better analyst, by
having a deeper understanding of
your tests.

27. Questions?

28. ASPAC’s Inter-Laboratory
Proficiency Programmes
(ILPP’s)

29. ASPAC’s Purpose
• Formed in 1990, with a key purpose to
“promote excellence in all aspects of soil
and plant tissue analysis.”
• The ILPP’s have been a major contributor
in achieving this.

30. ASPAC ILPP’s
• Initially run through the State Chemistry
Laboratory in Melbourne
• One soil and one plant programme p.a.
• Six samples sent out for each programme.
• Results reported in a formal report (taking up
to 6 months to prepare)
• The ILPP’s were of major benefit, improving
consistency amongst laboratories.

31. ILPP changes
• In the early 2000’s, SCL were struggling to keep
the service running.
• Also, one programme a year not frequent
enough
• Six months too long to report back
• In 2003, programmes contracted out to Global
Proficiency Ltd in New Zealand, an ISO
accredited provider.

32. ILPP changes (contd)
• Each program now runs 3x a year, with four
samples per round.
• Results reported back within two weeks.
– More use to participants to address problems
• ASPAC have also introduced a Certification
Programme. Good performers issued a
Certificate of Proficiency, and are listed on
ASPAC’s Website.

33. Benefits of these changes
• We have seen definite improvement in
performance.

34. More recent developments
• In 2014, introduced a separate programme
for Acid Sulphate Soils
– One round p.a., of four soils
– Certification is also granted
• This year, introducing a soil Physical Analysis
programme (texture, water holding capacity.)

35. Questions?