AGS Members' Day 2015 Educating Consultants on Laboratory Testing, Mike Cohen (DETS)

1. c
Educating Consultants on
Laboratory Testing
Mike Cohen
Technical Development
Manager
DETS
Members Day
18th March 2015

7. Typical environmental lab

8. In reality
• Picture of laboratory

9. No only joking

10. The Laboratory Process
Sampling
Receiving samples
Registering samples
Preparing samples
Extracting samples
Chemical analysis

11. Sampling
• Taking a representative sample is usually outside
the control of the lab.
• What is important
– Using the correct container for the analysis
– Filling them correctly
– getting them to the lab in a timely fashion
• If not the samples could be deviating and a
comment would go on the report to state the
integrity of the sample could be compromised

12. Sample Containers
• These are supplied by the laboratory and are
dependant on the type of analysis required.
– Plastic tub for Inorganic contaminants
– Glass jar for Organic contaminants
– Small glass jar with no headspace for volatile
contaminants

13. Not a good idea

14. What could possibly go wrong?
• Its all down to communication
• Or lack of it
• You know what you want
• Labs think we know what you want

15. On Receipt at the Lab
• Samples are checked against a chain of custody to
highlight any discrepancies, ambiguities, breakages
or deviating samples.
• Once this process has been completed and any
issues resolved, then the samples are ready for
registration onto The Laboratory Information
Management System (LIMS)

16. Receiving samples
• Is there sufficient instruction with the samples
• Could the instructions be ambiguous
• Is there sufficient detail
Things we are asked
• Can you tell me if this soil is contaminated?
• Can you tell me what it is?
• Can you tell me what’s in it?
• Being non specific can cause problems!

18. Registering samples at the lab
• Correct registration is very important since it determines
the analysis carried out and how it gets reported
– Have we got the correct det? – is total or dissolved det reqd
– Have we chosen the det with the correct unit - %, mg/kg,
µg/kg, g/l, mg/l, µg/l, ng/l
– Have we chosen the correct Form of Expression –
Ammoniacal nitrogen as N, as NH3, as NH4
– Have we included all the necessary information – sample
dates, depths, BH numbers, sample descriptions, TRTs,
dependant options, monohydric phenol or speciated.
• If not you could end up with something you didn’t want

20. Preparing samples
• Not all labs prepare samples the same way
– Some remove stones and analyse the remainder
– Some crush the whole sample and analyse it all
• A new ‘Blue Book’ written by the SCA is being
published by the EA which approves both
methods.
• IMPORTANT –you need to know which method
your lab employs

21. Preparation of soils samples
• Depending on what analysis is asked for
• Analysis is typically carried out on an air dried (30°C)
and ground sample where more representative sub
sample can be taken.
• However, some analyses, such as volatile organics are
carried out on an as received (AR) sample. Volatile
parameters would be lost if the sample was dried &
ground. This results in it being more difficult to take a
representative sub sample.

22. Procedure for preparation of soil
samples
• Whole sample hand mixed and quartered, one
quarter for air dried analysis and one for as received
• Air dried portion
• Dried at 30°C and moisture content recorded
• Stone content (>10mm) not recorded unless
specifically requested
• Whole dried sub-sample crushed to pass through a
450micron sieve
• As received wet portion
• Representative sub-samples are taken for each analysis

23. Extracting contaminants
• Labs tend not to analyse soil as such but extract
the contaminant of interest and analyse the
extract.
• Inorganic contaminants are digested in polar
solvents such as acids, whereas organic
contaminants are extracted into organic solvents

24. Chemical analysis - The Dark Art

25. Laboratory analysis
• Analysis tends to be split into 3 types
–Wet chemistry
– Organic
– Inorganic

26. Analytical Techniques
INORGANIC ORGANIC
SPECTROSCOPY
ATOMIC
ABSORPTION
ATOMIC
EMISSION
COLOURIMETRIC
SPECTROSCOPY
HPLC TLC GC
GC/MS
Flame - Heavy
metals
Furnace - Low
level
heavy
metals
Hydride - As,
Se, Sb
Cold Vapour
- Hg
Simultane
ous
ICP
ICP - MSOES
Sequential
ICP
Heavy
metals
& rare
earths
ICP + USN - Low
level
heavy
metals
Flame
Photometry -Na, K
& Li
}
ION
CHROMATOGR
APHY
(Conductivity
detector)
ECD, UV,
Fluoresce
nce
FI
D
EC
D
VOC
s
SVO
Cs
Phenols
PAHs
Elemental
Sulphur
Explosives
Pesticides
ANIONS
-CN
-SCN
-SO
-NH
-
Cl,S,F,N
O2
Class
separati
on
PAHs
Pesticid
es
PCBs
Chlorina
ted
Species
TPH
(EPH+G
RO)
Solvents
BTEX
CHROMATOGRAPHY

27. Quality in the Laboratory
• ISO 17025
– MCERTS
– UKAS
– Proficiency Testing Schemes
• Quality Control
– Reference materials
– Duplicates
– Blanks

28. When we say its 10mg/kg is it
• The answer is not really!
• All chemical analysis has a % uncertainty of
measurement which depends on the analyte
and the method employed.
• Typically it can range from 10% to 30%
(uncertainty in sampling is usually far greater)
• What this means is that the result reported is
within a range.

29. A few misconceptions
• The lower the limit of detection, the more
accurate the analysis
oNo the opposite is the case
• Results from different labs should always give the
same results
oNo it depends on the methods used
• Total results mean total
oFor organics, total means the total of the compounds
analysed

30. In conclusion
• Sampling is as important as analysis
• Differences in how a sample is prepared can
have a large influence on the final analytical
result
• The more information accompanying a
sample, the quicker the analysis becomes.

31. So what do consultants think of labs?
• Inflexible
– Labs try to be as flexible as possible but there are
limitations.
• We cannot do a five day test in 3 days (no matter how
much money is offered)
• If you only have 1g of sample then we cannot do a full
suite of analysis (we are not CSI)
• Despite appearances we are human and occasionally
we do make mistakes!

33. So what do labs think of consultants?
• Do labs think consultants expect too much?

35. I can assure you this is not what labs
think of consultants

37. Thank you