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Preservation and Holding Times

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The sample sizes, preservation procedures, holding times and conditions for air, aqueous and solid samples are recommendations and should be used as a guide.

Base your decision on the nature of the sample, the intended use of the data and the data quality objectives, e.g. alternative storage conditions are acceptable if analyte stability within a matrix can be demonstrated and data quality objectives are not compromised.

In a given sample, the analyte requiring the most preservation treatment as well as the shortest holding time should dictate the preservation treatment of the sample overall.

A downloadable PDF for solid and aqueous samples can be obtained here.

For further information please contact customerservice@measurement.gov.au, 1300 722 845 or use our on-line form.

General Rules for Samples

  • Place in ice immediately after sampling
  • Cool to <4 °C
  • Deliver to NMI within 24 hours of sampling
  • Use ice bricks when dispatching by air and over long distances, and when couriers will not freight ice
  • Have at least half the recommended holding time remaining when relinquished to NMI
  • Avoid delivering time-critical samples to NMI late on Fridays

References

AS 3550.1:1988 Methods for the Analysis of Waters — Determination of Dissolved Sulphide — Spectrophotometric Method

AS/NZS 5667.1:1998 Water Quality — Sampling — Guidance on the Design of Sampling Programs, Sampling Techniques and the Preservation and Handling of Samples

ASTM D1946 Standard Practice for Analysis of Reformed Gas by Gas Chromatography

APHA Standard Methods for the Examination of Water and Wastewater, 22nd edition, American Public Health Association

CARB429 Method 429 — Determination of Polycyclic Aromatic Hydrocarbon Emissions from Stationary Sources, California Air Resources Board

MassDep APH Method for the Determination of Air-phase Petroleum Hydrocarbons, Massachusetts Department of Environmental Protection

NAGD National Assessment Guidelines for Dredging 2009, Department of the Environment, Water, Heritage and the Arts

NEPM National Environment Protection (Assessment of Site Contamination) Measure 1999, Schedule B(3) amended 2013, NSW Environmental Protection Authority

US EPA MIO-3.1 Compendium of Methods for the Determination of Inorganic Compounds in Ambient Air, Method IO-3.1 Selection, Preparation and Extraction of Filter Material)

US EPA SW-846 Test Methods for Evaluating Solid Waste, Physical/Chemical Methods

Other US EPA Test Method Collections

Air Samples

Test Container Preservation procedure (treatment after collection until arrival at NMI) Holding time
(maximum time from collection until analysis) 		Reference
Volatile organic compounds (VOC) canister nil 30 days US EPA TO15
VOC tube cool to <4 °C 30 days US EPA TO17
VOC tube, passive sampler cool to <4° C 14 days US EPA 8260
Sulphur compounds canister nil 72 hours NMI method
Metals impinger solutions, filters cool to ≤6 °C 30 days US EPA M29, US EPA MIO-3.1
Metals (general including CrVI) filters/sorbents cool to ≤6 °C 30 days (14 days for CrVI) US EPA 3060A
Sulphate (H2SO4/SO3/SO2) impinger solutions, filters nil not available APHA 4110B, US EPA M8
Polycyclic aromatic hydrocarbons (PAH) XAD resin, filter, rinse cool to 4 °C, dark  7 days CARB429
Nitrate (NOx) impinger solution, filter nil 4 days APHA 4110B, US EPA M7A
Fluoride (HF/F2), chloride (HCl/Cl2), bromide (HBr/Br2) impinger solution, filter nil not available APHA 4110B, US EPA 26
Formaldehyde silica gel tube cool to <4 °C 14 days US EPA TO11
Dioxins (PCDD/PCDF) XAD resin, filter, rinse cool to <4 °C 30 days US EPA M23, US EPA 1613
Dioxins (PCDD/PCDF) PUF tube, filters cool to <4 °C 30 days US EPA TO-9A, US EPA 1613
Dioxin-like polychlorinated biphenyl (PCB) XAD resin, filter, rinse cool to <4 °C 30 days US EPA M23, US EPA 1668
Dioxin-like PCB PUF tube, filters cool to <4 °C 30 days US EPA TO-9A, US EPA 1613
Chlorobenzenes, chlorophenols XAD resin, filter, rinse cool to <4 °C 7 days US EPA 8270
Semi-volatile organics XAD tube cool to <4 °C 7 days US EPA 8270
Ammonia impinger solutions nil not available APHA 4500-NH3G
Hydrocarbons canister ambient 30 days MassDEP APH
OCP/OPP/PCB PUF tube cool to <4 °C 7 days US EPA 8081, US EPA 8141
PAH XAD Tube cool to <4 °C 7 days US EPA 8270
PAH PUF tube, filters cool to <4 °C 7 days US EPA TO-13A
Particulate matter (gravimetric analysis) dust filter nil not available AS 3580.9.10, AS 3640, US EPA M5
PCB XAD or PUF tube cool to <4 °C 7 days US EPA 8081
Permanent gases canisters ambient 30 days ASTM D1946

Aqueous Samples

During sampling, do not to rinse out or spill preservatives

Avoid cross-contaminating bottles (e.g. nitric acid used for metals can contaminate nitrate analysis)

Some tests must minimise exposure to air to avoid analyte losses

If tests require the addition of preservatives prior to sampling, contact NMI beforehand to facilitate supply of appropriate containers

For tests marked with a “†”, if residual chlorine is present, add 80 mg sodium thiosulphate per 1000 mL of sample.

Field filtration is mandatory or recommended for many tests:

  • dissolved metals (such as groundwaters) samples should be 0.45 μm filtered into a HNO3 preserved bottle (if samples have not been field filtered and acidified, NMI will filter on receipt from an unpreserved sample container then acidify)
  • total recoverable metals (such as surface waters) samples should be placed unfiltered into a HNO3 preserved bottle (if samples have not been field preserved, NMI will sub-sample from the unpreserved bottle on receipt and acidify with HNO3)

In the sample size column below, * indicates that larger volumes are required for lower limiting of reporting analyses.

Test Container Sample size (low levels of organics require 1 L or 2 L) Preservation procedure
(treatment after collection until arrival at NMI) 		Holding time (maximum time from collection until analysis) Reference
Alkalinity/acidity plastic 50 mL cool to <4 °C 14 days APHA
BOD plastic 500 mL cool to <4 °C 2 days APHA
Bromide plastic 50 mL cool to <4 °C, dark 28 days APHA
Carbon – TOC glass 40 mL pH <2 (H2SO4 ), cool to <4 °C 28 days APHA
Carbon – Dissolved Organic Carbon glass 40 mL filter onsite, pH <2 (H2SO4), cool to <4 °C 28 days APHA
Chlorophyll-a plastic 1000 mL cool to <4 °C, dark 2 days APHA
plastic 1000 mL filter, freeze residue 28 days APHA
Chlorine plastic 50 mL nil, field test only 30 min APHA
Chlorine (for sealed bottled water) plastic 50 mL sealed bottled water only 30 min after opening APHA
Chloride plastic 50 mL nil 28 days APHA
Chromium hexavalent plastic 50 mL cool to <4 °C 1 day APHA
plastic 50 mL pH >12 (NaOH), cool to <4 °C 28 days US EPA 1669
COD plastic 50 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
Colour plastic 50 mL cool to <4 °C, dark 2 days APHA
Conductivity plastic 50 mL cool to <4 °C 28 days APHA
Cyanides† plastic 200 mL pH >12 (NaOH), cool to <4 °C, dark 14 days APHA
Dioxins† amber glass 2 x 1000 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 1 year until (1 after) extraction US EPA 1613
Ferrous iron glass 40 mL pH <2 (HCl), no headspace 3 days NMI 2010
Fluoride plastic 50 mL none required 28 days APHA
Haloacetic acids vial 2 x 40 mL 4 mg NH4Cl per vial, zero headspace and cool to <4 °C 14 days US EPA 552.3
Hardness plastic 50 mL cool to <4 °C or pH <2 (HNO3) 7 days or 6 months AS/NZS 5667.1:1998 and APHA
Herbicides (includes glyphosate) glass 200 mL* cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Iodide plastic 50 mL cool to <4 °C 28 days AS/NZS 5667.1:1998
MBAS glass 200 mL cool to <4 °C 2 days APHA
Mercury plastic 100 mL pH <2 (HNO3) 28 days APHA
glass 100 mL pH <2 (HNO3), 0.05% potassium dichromate 1 month AS/NZS 5667.1:1998
Metals – total plastic 100 mL pH <2 (HNO3) 6 months APHA
Metals – filtered plastic 100 mL filter onsite, pH <2 (HNO3) 6 months APHA
Microbiology (in natural) plastic (sterile) 200 mL cool to <4 °C 1 day AS/NZS 5667.1:1998
Microbiology (in tap, i.e. chlorinated) plastic (sterile) 200 mL cool to <4 °C, Na2S2O3 1 day AS/NZS 5667.1:1998
N (ammonia) plastic 50 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
N (nitrate) plastic 50 mL cool to <4 °C 2 days APHA
N (nitrate) plastic 50 mL filter on site, freeze 28 days AS/NZS 5667.1:1998
N (nitrite) plastic 50 mL cool to <4 °C 2 days APHA
N (TKN) plastic 50 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
N (total) plastic 50 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
Oil and grease glass 1000 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
Organochlorine pesticides glass 200 mL* cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Organophosphorus pesticides glass 200 mL* cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Organotins (tributyl tin – TBT) glass 1000 mL cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
PAHs† glass 200 mL* cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 7 days until (40 after) extraction US EPA SW-846
PBDEs† amber glass 2 x 1000 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 1 year until (1 after) extraction US EPA 1614
PCBs† (dioxin-like) amber glass 2 x 1000 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 1 year until (1 after) extraction US EPA 1668
PCBs† glass 200 mL* cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 7 days until (40 after) extraction US EPA SW-846
PFAS† (including PFOS and PFOA) HDPE 2 x 60 mL cool to <4 °C 14 days until (28 after) extraction US EPA 537 ISO 5667-3
pH plastic 50 mL cool to <4 °C 3 days NMI 2010
Phenols (speciated) glass 200 mL* cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Phenols (total) plastic or glass 100 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
Phenoxy acid herbicides glass 200 mL* cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Phosphorus – total plastic 100 mL pH <2 (HNO3) 28 days APHA
Phosphate plastic 50 mL cool to <4 °C 2 days APHA
Phosphate plastic 50 mL filter onsite, freeze 28 days AS/NZS 5667.1:1998
Phthalates glass 200 mL* cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Sulphate plastic 50 mL cool to <4 °C 28 days APHA
Sulphide (dissolved) plastic 100 mL filter, add 10 mL Cu 2,4 DMP (per 100 mL sample), cool to <4 °C 7 days AS 3550.1
Sulphide (total) plastic 100 mL cool, add 0.5 mL 2N zinc acetate and 1 mL 6N NaOH (per 100 mL sample), cool to <4 °C 7 days APHA
SVOCs (includes ethers, amines, nitroaromatics, nitrosamines) glass 200 mL* cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 7 days until (40 after) extraction US EPA SW-846
TDS plastic 50 mL cool to <4 °C 7 days APHA
Thiocyanate plastic 100 mL add HNO3 or H2SO4 to pH<2, cool to <4 °C 28 days APHA
TRH (C6–C10)/BTEX vial 2 x 40 mL pH <2 (H2SO4 or HCl), cool to <4 °C, zero headspace (if residual chlorine is present add 80 mg Na 2S2O3 per 1000 mL of sample before adding acid — use NaHSO4 if dangerous goods restrictions apply) 14 days US EPA SW-846
TRH (C10–C40) glass 200 mL* cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 7 days until (40 after) extraction US EPA SW-846
Trihalomethanes vial 2 x 40 mL pH <2 (H2SO4 or HCl), cool to <4 °C, zero headspace (if residual chlorine is present add 80 mg Na 2S2O3 per 1000 mL before adding acid) 14 days US EPA SW-846
TSS plastic 500 mL cool to <4 °C 7 days APHA
Turbidity plastic 100 mL cool to <4 °C, store in dark 2 days APHA
VOCs (includes C1–C5, halogenated aliphatics, halogenated aromatics, monocyclic aromatics and alcohols) vial 2 x 40 mL pH <2 (H2SO4 or HCl), cool to <4 °C, zero headspace (if residual chlorine is present add 80 mg Na 2S2O3 per 1000 mL of sample before adding acid — use NaHSO4 if dangerous goods restrictions apply) 14 days US EPA SW-846

† If residual chlorine is present, add 80 mg sodium thiosulphate per 1000 mL of sample.

 

Drinking Water (Not Bottled)

During sampling, do not to rinse out or spill preservatives.

Avoid cross-contaminating bottles (e.g. nitric acid used for metals can contaminate nitrate analysis).

Some tests must minimise exposure to air to avoid analyte losses.

If tests require the addition of preservatives prior to sampling, contact NMI beforehand to facilitate supply of appropriate containers.

Many of the preservatives are hazardous chemicals (eg strong acids, alkaline solutions) and they must be handled with care — we recommend you wear safety glasses and gloves.

For product water, please supply (as would be delivered to the consumer) at least 15 L in sealed containers all with the same packing date or UBD. If pack size is greater than 15 L, please supply one unit as a sealed package — do not split or sub-sample bulk containers.

Test Container Sample size
(low levels of organics require 1 L or 2 L) 		Preservation procedure
(treatment after collection until arrival at NMI) 		Holding time
(maximum time from collection until analysis) 		Reference
Absorbance plastic 50 mL cool to <4 °C 14 days APHA
Alkalinity plastic 50 mL cool to <4 °C 14 days APHA
Ammonia – N plastic 50 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
Bromate (BrO3–) plastic or glass 40 mL 50 mg/L EDA, cool to <4 °C 28 days US EPA Method 302.0
Bromide plastic 50 mL cool to <4 °C, dark 28 days APHA
Chlorate (ClO3–) plastic or glass 40 mL 50 mg/L EDA, cool to <4 °C 28 days US EPA Method 302.0
Chloride plastic 50 mL nil 28 days APHA
Chlorine plastic 50 mL nil, field test only 30 min APHA
Chlorine, chloramine plastic 50 mL sealed bottled water only 30 min after opened APHA
Chlorite (ClO2–) plastic or glass (opaque) 40 mL 50 mg/L EDA, cool to <4 °C 14 days US EPA Method 302.0
Chloroacetic acids vial 2 x 40 mL 4 mg NH4Cl per vial, zero headspace, cool to <4 °C 14 days US EPA 552.3
Chromium hexavalent plastic 50 mL cool to <4 °C 1 day APHA
plastic 50 mL pH >12 (NaOH), cool to <4 °C 28 days US EPA 1669
COD plastic 50 mL pH <2 (H2SO4), cool to <4 °C 28 days APHA
Colour plastic 50 mL cool to <4 °C, dark 2 days APHA
Conductivity plastic 50 mL cool to <4 °C 28 days APHA
Cyanides plastic 200 mL pH >12 (NaOH), cool to <4 °C, dark 14 days APHA
Dioxins amber glass 2 x 1000 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 1 year until (1 after) extraction US EPA 1613
Fluoride plastic 50 mL none required 28 days APHA
Formaldehyde glass 40 mL None required 7 days subcontracted
Gross alpha/beta plastic 1000 mL cool to <4 °C 28 days subcontracted
Hardness plastic 50 mL cool to <4 °C or pH <2 (HNO3) 7 days or 6 months AS/NZS 5667.1:1998 and APHA
Herbicides (includes glyphosate) glass 500 mL cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Iodide plastic 50 mL cool to <4 °C 28 days AS/NZS 5667.1:1998
Iodine plastic 50 mL none required 28 days APHA
Iron – ferrous glass 40 mL pH <2 (HCl), no headspace 3 days NMI 2010
Mercury plastic 100 mL pH <2 (HNO3) 28 days APHA
glass 100 mL pH <2 (HNO3), 0.05% K2Cr2O7 1 month AS/NZS 5667.1:1998
Metals – total plastic 100 mL pH <2 (HNO3) 6 months APHA
Micro (in natural) plastic (sterile) 200 mL cool to <4 °C 1 day AS/NZS 5667.1:1998
Micro (in tap,
i.e. chlorinated) 		plastic (sterile) 200 mL cool to <4 °C, Na2S2O3 1 day AS/NZS 5667.1:1998
N (nitrate) plastic 50 mL cool to <4 °C 2 days APHA
N (nitrite) plastic 50 mL cool to <4 °C 2 days APHA
Organotins
(tributyl tin – TBT) 		glass 1000 mL cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
PAHs glass 1 x 500 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 7 days until (40 after) extraction US EPA SW-846
PBDEs amber glass 2 x 1000 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 1 year until (1 after) extraction US EPA 1614
PCBs (dioxin-like) amber glass 2 x 1000 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL) 1 year until (1 after) extraction US EPA 1668
PCBs glass 500 mL cool to <4 °C* 7 days until (40 after) extraction US EPA SW-846
Pesticides glass 1 x 500 mL cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
pH plastic 50 mL cool to <4 °C 3 days NMI 2010
Phenols (speciated) glass 1 x 500 mL cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Phosphate plastic 50 mL cool to <4 °C 2 days APHA
Phosphate plastic 50 mL filter onsite, freeze 28 days AS/NZS 5667.1:1998
Phthalates glass 500 mL cool to <4 °C 7 days until (40 after) extraction US EPA SW-846
Radium 226/228 plastic 2 x 1000 mL cool to <4 °C 28 days subcontracted
Sulphate plastic 50 mL cool to <4 °C 28 days APHA
Sulphide (dissolved) plastic 100 mL filter, add 10 mL Cu 2,4 DMP (per 100 mL sample), cool to <4 °C 12 hours AS 3550.1
Sulphide (total) plastic 100 mL cool, add 0.5 mL 2N zinc acetate and 1 mL 6N NaOH (per 100 mL sample), cool to <4 °C 7 days APHA
SVOCs (includes ethers, amines, nitroaromatics, nitrosamines) glass 500 mL cool to <4 °C (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 7 days until (40 after) extraction US EPA SW-846
Total dissolved solids plastic 50 mL cool to <4 °C 7 days APHA
Thiocyanate plastic 100 mL add HNO3 or H2SO4 to pH<2, cool to <4 °C 28 days APHA
Trihalomethanes vial 2 x 40 mL pH <2 (H2SO4 or HCl), cool to <4 °C, zero headspace (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 14 days US EPA SW-846
Turbidity plastic 100 mL cool to <4 °C, store in dark 2 days APHA
VOCs(includes C1–C5, halogenated aliphatics and aromatics, monocyclic aromatics, alcohols) vial 2 x 40 mL pH <2 (H2SO4 or HCl), cool to <4 °C, zero headspace (if residual chlorine is present add 80 mg Na2S2O3 per 1000 mL before adding acid) 14 days US EPA SW-846

Solid Samples

Test Container Sample size Preservation procedure (treatment after collection until arrival at NMI) Holding time (maximum time from collection until analysis) Reference
Bromide plastic or glass 20 g air dry or field moist 28 days NEPM
Carbon (TOC) glass 20 g air dry or field moist 28 days NEPM
Chloride plastic or glass 20 g air dry or field moist 28 days NEPM
Conductivity plastic or glass 20 g air dry or field moist 7 days NEPM
Cyanides plastic or glass 20 g field moist 14 days NEPM
Dioxins glass 100 g cool to <4 °C 1 year until (1 after) extraction US EPA 1613
Fluoride plastic or glass 20 g air dry or field moist 28 days NEPM
Herbicides glass 20 g or 1 x 125 mL cool to <4 °C 14 days US EPA SW-846
Hexavalent chromium plastic 20 g field moist 28 days NEPM
Mercury plastic 20 g field moist 28 days NEPM
Metals plastic or glass 20 g air dry or field moist 6 months NEPM
Moisture plastic or glass 20 g field moist 14 days NEPM
Organochlorine pesticides glass 20 g or 1 x 125 mL cool to <4 °C 14 days until extraction, 40 days until analysis US EPA SW-846
Organophosphorus pesticides glass 20 g or 1 x 125 mL cool to <4 °C 14 days until extraction, 40 days until analysis US EPA SW-846
Organotins (tributyl tin – TBT) glass 20 g or 1 x 125 mL cool to <4 °C 14 days NAGD
PAHs glass 20 g or 1 x 125 mL cool to <4 °C 14 days until extraction, 40 days until analysis US EPA SW-846
PBDEs glass 100 g cool to <4 °C 1 year until (1 after) extraction US EPA 1614
PCBs (dioxin-like) glass 100 g cool to <4 °C 1 year until (1 after) extraction US EPA 1668
PCBs glass 20 g or 1 x 125 mL cool to <4 °C 14 days until extraction, 40 days until analysis US EPA SW-846
PFAS (including PFOS and PFOA) HDPE 250 mL jar cool to <4 °C 60 days until (30 days after) extraction US EPA 821-R-11-007
pH plastic or glass 20 g air dry or field moist 7 days NEPM
Phenols glass 20 g or 1 x 125 mL jar cool to <4 °C 14 days until extraction, 40 days until analysis US EPA SW-846
Sulphate plastic or glass 20 g air dry or field moist 28 days NEPM
SVOC (includes pesticides, herbicides, chlorinated hydrocarbons) glass 20 g or 1 x 125 mL cool to <4 °C 14 days until extraction, 40 days until analysis US EPA SW-846
TCLP plastic or glass 50 g as per analyte as per analyte US EPA 1311
TRH (C6–C10)/BTEX glass 20 g or 1 x 125 mL cool to <4 °C, minimise headspace 14 days US EPA SW-846
TRH (C10–C40) glass 20 g or 1 x 125 mL cool to <4 °C 14 days US EPA SW-846
VOCs (includes halogenated aliphatics and aromatics, monocyclic aromatics, alcohols) glass 20 g or 1 x 125 mL cool to <4 °C, minimise headspace 14 days (7 days for vinyl chloride and styrene) US EPA SW-846