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We recommend the following preservation procedures, holding times and conditions when submitting air samples for testing by the National Measurement Institute (NMI). Please treat these recommendations as a guide only.

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

References 

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Last updated: 1 December 2020

Content ID: 64627