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

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 Pb mg/kg 3500 3000 2500 2000 mg/kg Series1 1500 1000 500 0 0 10 20 30 40 50 60 samples

Copper - OK Cu mg/kg 700 600 500 400 mg/kg Series1 300 200 100 0 0 10 20 30 40 50 60 samples

Chromium – non homogenous Cr mg/kg Series1 300 250 200 mg/kg 150 100 50 0 0 10 20 30 40 50 60 sample

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 The Effect of Time on the Co-precipitation of Metals in a Neutralised Zn Solution Containing 10 ppm Iron and 100ppb of Each Analyte. Co Ni Cu Cd 120 Pb 100 ppb in solution 80 60 40 20 0 0 1 3 5 7 Elapsed Time (hrs)

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 Holding Time Old NEPM 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, G 14 days 7 days 2-chloroethyl vinyl ester

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 Diesel, other petroleum fuels, mineral solvents oils and petroleum based solvents

Semi Volatile Fractions Fractions >C10 – C16 >C16 – C34 >C34 – C40 • 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).

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 Diesel spiked Woodchips - TRH – Silica Gel cleaned C10-C14 : 410ppm C10-C14 : 380ppm C15-C28: 1500ppm C15-C28 : 910ppm C29-C36 : 600ppm C29-C36: 140ppm The last 2 fractions yield a lower result after the silica gel cleanup, emphasizing the importance of 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 New TRH Band Reporting C10-C14: C>9-C14 : 180ppm >C10-C16: 270ppm C15-C28: C>14-C28 : 280ppm >C16-C34: 190ppm C29-C36: C>28-C36 : <PQL >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 = C 6 -C 10 less BTEX (as BTEX HSLs characterised) • F2 = >C 10 – C 16 less Naphthalene (as Naphthalene HSL characterised) From NEPM B1 (CCME)

F1, F2 continued • F2 = >C 10 – C 16 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 of 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