AGS Members' Day 2015 - Educating Consultants on Laboratory Testing Presentation

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Educating Consultants on Laboratory Testing

Mike CohenTechnical Development

ManagerDETS

Members Day 18th March 2015

Typical environmental lab

In reality

• Picture of laboratory

No only joking

The Laboratory Process

Sampling

Receiving samples

Registering samples

Preparing samples

Extracting samples

Chemical analysis

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

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

Not a good idea

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

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)

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!

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

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

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.

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

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

Chemical analysis - The Dark Art

Laboratory analysis

• Analysis tends to be split into 3 types

–Wet chemistry

– Organic

– Inorganic

Analytical TechniquesINORGANIC ORGANIC

SPECTROSCOPY

ATOMIC

ABSORPTION

ATOMIC

EMISSION

COLOURIMETRIC

SPECTROSCOPYHPLC TLC GC

GC/MS

Flame - Heavy metals

Furnace - Low level

heavy metals

Hydride - As, Se, Sb

Cold Vapour - Hg

Simultaneous

ICP

ICP - MSOES

Sequential

ICP

Heavy metals

& rare earths

ICP + USN - Low level

heavy metals

Flame

Photometry -Na, K & Li

}

ION

CHROMATOGRAPHY

(Conductivity

detector)

ECD, UV,

Fluorescence

FID

ECD

VOCs

SVOCs

Phenols

PAHs

Elemental Sulphur

Explosives

Pesticides

ANIONS

-CN

-SCN

-SO

-NH

-Cl,S,F,NO2

Class

separation

PAHs

Pesticid

es

PCBs

Chlorinated

Species

TPH

(EPH+GRO)

Solvents

BTEX

CHROMATOGRAPHY

Quality in the Laboratory

• ISO 17025– MCERTS

– UKAS

– Proficiency Testing Schemes

• Quality Control– Reference materials

– Duplicates

– Blanks

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 analyteand 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.

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

o For organics, total means the total of the compounds analysed

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.

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!

So what do labs think of consultants?

• Do labs think consultants expect too much?

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

Thank you