Sampling Techniques to Ensure Quality Results David Springer ACLCA - - PowerPoint PPT Presentation

Sampling Techniques to Ensure Quality Results

David Springer – ACLCA Adelaide June 2013

Tonight

• Measurement Uncertainty
• Poor Sampling Examples
• NEPM Preservations/Holding Times
• NEPM – TRH v’s TPH
• NEPM – F1/F2
• NEPM – BaP TEQ
• NEPM – WA Asbestos
• NEPM – B7
• Transport of Samples – Ice
• Acknowledgement – Thanks to ALS for assisting with some information

Measurement Uncertainty (MU)

• ‘A parameter associated with the

result of a measurement that characterises the dispersion of the values that could reasonably be attributed to the measurand’

• (international vocabulary of basic & general terms in metrology)

Simple Definition of MU

• Basically – how sure is the lab of the result?
• It is a range containing the ‘true value’ with a stated level
• f confidence

– eg: Lead in soil has a MU of 10%. We test a soil & report to you 20 mg/kg. – We are 95% confident that the concentration of Lead is somewhere between 18mg/kg & 22mg/kg

How to Calculate – various ways

• Precision and Bias
• Last resort – professional judgement

Analyte M U % Alkalinity 21 Chloride 15 Sulfate 17 Nitrate 14 Nitrite 13 TSS 16 pH 3 Aluminium 18 Cobalt 21 M ercury 16

MU continued

• Depends on matrix and PQL

– eg: OC to 0.001ppm = 80%, to 0.1ppm = 15%

• Small uncertainty – reliable
• Large uncertainty – caution may be appropriate
• Biggest contributor to MU is sampling!

Conundrum

• Lab reports 1 mg/L for Lead
• Guideline value is 1mg/L
• Lab MU is 10% (ie: 0.9 – 1.1 mg/L)
• Is your result over the limit?

Our results are only as good as your Sampling.

• If you don’t get the sampling right, the

testing may be a waste of money and your interpretations will be flawed.

How much do we actually take?

• 250g soil jar
• 10g PAH
• 5g BTEX
• 3g Metals
• 40g Asbestos

Foundry Soil

Lead – not too bad

500 1000 1500 2000 2500 3000 3500 10 20 30 40 50 60 mg/kg samples

Pb mg/kg

Series1

Copper - OK

100 200 300 400 500 600 700 10 20 30 40 50 60 mg/kg samples

Cu mg/kg

Series1

Chromium – non homogenous

50 100 150 200 250 300 10 20 30 40 50 60 mg/kg sample

Cr mg/kg

Series1

Pb in top 60mg/kg, Pb in bottom <1mg/kg

Not the best

Water - Field Duplicates

Water Field Duplicates

Duplicates? – Apparently Yes!

Acidification of Metals

20 40 60 80 100 120 1 3 5 7

ppb in solution Elapsed Time (hrs)

The Effect of Time on the Co-precipitation of Metals in a Neutralised Solution Containing 10 ppm Iron and 100ppb of Each Analyte.

Zn Co Ni Cu Cd Pb

Filter v no filter - Fe Dropped out of solution

Always take a good QC sample

BaP (PAH) Duplicate - <0.1mg/kg top, 5mg/kg bottom

Hg Hotspots – Lab Duplicate was 4 & 40 mg/kg

NEPM Changes

Analyte Container Holding Time Old NEPM Holding Time NEW NEPM Cyanide P, PTFE, G 7 days 14 days Fluoride P, G 7 days 28 days Metals P (old) P/G (new) 6 months 6 months Mercury P (also Cr6) P 28 days 28 days (7 days Hex) VOC (except below) G 14 days 14 days

Vinyl chloride, styrene, 2-chloroethyl vinyl ester

G 14 days 7 days

TPH v TRH

• 2 new methods – TRH and TRH (silica)
• No longer referred to as TPH
• All labs will now extract/analyse/calculate/report the same way
• Advantages of New Fractions
• More info to make reasonable risk assessments
• Gains of New Method
• Standardisation of banding amongst labs = more consistent data
• Tightening of performance requirements
• The Term TRH is equivalent to the historically reported TPH

Banding

Volatile (vTRH) Semi Volatile (svTRH) Was C6-C9 Was C10-C36 Now C6-C10 Now >C10-C40 Petrol, light fuel, petroleum based solvents Diesel, other petroleum fuels, mineral

• ils and petroleum based solvents

Semi Volatile Fractions

• Interferences
• TRH includes any organic compounds that are soluble in the relevant

solvent(s) and elute under a linear GC program method conditions.

• Can include vegetable & animal oils, fats, plasticisers and solvents i.e.

Biogenic plus any Petrogenic hydrocarbons

• The use of silica gel to adsorb polar compounds may reduce potential false

positives from Biogenic material thus yielding a result more reflective of any petroleum contamination (where applicable). Fractions >C10 – C16 >C16 – C34 >C34 – C40

What is Silica Gel Cleanup

• After a sample is extracted in solvent the solvent extract is

poured through a column containing silica gel (or can be mixed in the extraction vessel directly). The solvent extract runs down through the column slowly, over the surface of the silica gel particles. The silica gel retains the more polar compounds that were co-extracted from the sample, allowing the less polar petroleum based compounds to flow through ready for GC-FID analysis.

• Note, Silica Gel analysis is only applicable to semi-volatile

fractions.

Diesel spiked Woodchips - TRH C10-C14 : 410ppm C15-C28: 1500ppm C29-C36 : 600ppm Diesel spiked Woodchips - TRH – Silica Gel cleaned C10-C14 : 380ppm C15-C28 : 910ppm C29-C36: 140ppm The last 2 fractions yield a lower result after the silica gel cleanup, emphasizing the importance

• f determining TRH – Silica Gel where Biogenic material can lead to false positives.

The term ‘TRH-Silica’ is used as the separation of petrogenic and biogenic is not absolute!

Banding – Old v New NEPM

Old TPH Band Reporting C10-C14: C>9-C14 : 180ppm C15-C28: C>14-C28 : 280ppm C29-C36: C>28-C36 : <PQL New TRH Band Reporting >C10-C16: 270ppm >C16-C34: 190ppm >C34-C40 : <PQL

The banding is now defined specifically in NEPM B3 with respect to certain n-alkane markers and must be adhered to!

F1, F2

In order to compare to HSLs, F1 and F2 are defined as:-

• F1 = C6-C10 less BTEX (as BTEX HSLs characterised)
• F2 = >C10 – C16 less Naphthalene (as Naphthalene HSL characterised)

From NEPM B1 (CCME)

F1, F2 continued

• F2 = >C10 – C16 less Naphthalene
• Napthalene for this subtraction will be taken from the BTEX analysis (due to

BTEX generally being run with TRH). Most labs will do this, though NEPM does not say!

• Otherwise, a separate PAH run (and charge) would possibly occur.
• Always subtraction from BTEX run, even if PAH’s are done – keep

consistent.

• Napthalene by P&T (BTEX) v’s Napthalene by GC-MS
• Soils – different extraction (methanol v DCM-Acetone), different

instrumentation

• Waters – different preservatives, different instrumentation

WA Asbestos

• WA method = 10x more conservative than the Netherlands to account for

dryer Australian soils

• WA = 0.001% asbestos in soil for FA (Fibrous Asbestos) & AF (Asbestos

Fines)

• However, 0.01% remains the standard LOR for AS4964 method
• The examination of 500ml may improve the likelihood of identifying

asbestos

• Any reporting of <0.01% MUST be NON NATA – Further info TBA

WA Asbestos

• A positive result would normally be considered by DOH to exceed

the 0.001% w/w investigation criteria applied to fine asbestos material, especially given that a 0.01% LOD usually applies.

• However, a single such exceedance may not necessarily result in

the sample source being deemed contaminated.

• A weight of evidence approach should be used by the consultant,

auditor and regulator in assessing the significance of an exceedance, which should take account of the history of the site and frequency and occurrence of other positive and negative results.

Schedule B7 – Free Cyanide

• HIL has been derived for Free Cyanide
• However, the measurement of Free CN is difficult
• So, Schedule B3 recommends WAD CN as a conservative measure
• f Free CN.

Schedule B7 (Table 1A(1) HIL) - Mirex

• Phased out of Australia in 2007
• Prior to 2007, only used in NT for Giant Termite Control in Mango

Trees

• Never Detected before in Australian Food (FASANZ 2001)
• No Background concentration data available in Australia

Schedule B7 - (Table 1A(1) HIL) - Toxaphene

• Mainly available 1940’s to 1980’s
• Still used in some parts of Africa and Asia
• Mainly used in Cotton, Grains, Fruits/Veg, Nuts, Cattle
• NEVER USED in AUSTRALIA !

Benzo (a) Pyrene TEQ

• B(1) includes HIL’s for BaP as Toxic Equivalents (TEQ)
• This is the comparison of 8 carcinogenic PAH’s relative to BaP
• Labs will do this calculation for you

Sample Transport

• Old NEPM – Ice or 4 degree refrigerated transport
• New NEPM – Preferably ice bricks or refrigerated container
• ELIG preferred option has always been –
• Cool samples in either fridge or ice
• Then - transport to lab with ice bricks or double-bagged ice (not free

flowing ice)

• Free flowing ice can easily melt, and potentially contaminate your

samples.

Potential Cross Contamination

Potential Cross Contamination?

Hydrocarbon Contamination?

Cairns to Sydney does need Bubble Wrap!

Floating in Ice Mud

Ice water penetration - contamination

Esky Ice water

esky water

• Al = 200,000 ppb
• As = 35 ppb
• Cd = 7 ppb
• Co = 930 ppb
• Cu = 3700 ppb
• Fe = 600,000 ppb
• Pb = 120 ppb
• Mn = 55,000 ppb
• Ni = 450 ppb
• U = 24 ppb

esky water + sampling rubbish

• Al = 6000 ppb
• Cu = 15 ppb
• Fe = 7500 ppb
• Pb = 40 ppb
• Mn = 60 ppb
• Zn = 80 ppb
• Ba = 120 ppb
• Sn = 20 ppb
• V = 10 ppb

Metals (total) in melted esky ice

Sydney Sydney Country NSW Sydney West NSW Aluminium (ppb) 1,300 200,000 5,700 22,000 140 Arsenic (ppb) 2 35 2 20 1 Cadmium (ppb) <0.1 7 0.2 0.9 0.1 Chromium (ppb) 1 120 6 44 5 Cobalt (ppb) 5 930 1 28 <1 Iron (ppb) 1,500 600,000 7,500 24,000 380 Lead (ppb) 1 120 35 49 3 Zinc (ppb) 23 660 77 350 31 Manganese (ppb) 130 55,000 56 540 14

Duct Tape Sealed Bottles

Duct Tape Sealed Bottles

• The melted ice water was analysed for VOC’s:
• Toluene = 520 ppb
• (detection limit is 1 ppb)

Red Texta Stained Ice Water (from label ID’s)

Texta Water – VOC Analysis

• Benzene = 20 ppb
• Toluene = 190 ppb
• Ethyl Benzene = 2 ppb
• Xylenes = 4 ppb
• (Detection limit is 1µg/L = 1ppb)

Esky ice with a sheen?

Esky ice with a sheen - results

• Benzene = 2,100ug/L
• Xylenes – 4,300 ug/L
• Napthalene = 240 ug/L
• C10-C14 TRH = 7,000 ug/L
• C15-C28 TRH = 6,600 ug/L

What’s the Solution?

• Cool samples in ice/fridge – then

transport with ice bricks

• Use ice, but double bag it. Don’t leave

it free flowing.

What the Lab needs from you

• Clearly written and correct COC’s
• (PB won our 2012 $500 prize for consistently good

COC’s). Over 50% of all COC’s have issues

• Correct sampling – right bottles, metals filtered if

needed (and ticked)

• Samples packed to avoid breakages
• Samples packed to avoid cross contamination
• Any doubts – just ask the lab. We don’t mind.

Asbestos or Soil?

Well, I guess we do ask for a separate bag!

No Ice Bricks? At least they made the effort!

Started a trend?

Again?

Ice Brick Fail !

Bacon Brick? – Fail. (the note says `sorry about the bacon J ’)

As an Industry – lets get rid of Bad Ice

And only use Good Ice

Photo: Tom Raftery