Detection of chlorpyrifos in air using low volume polyurethane foam (PUF) sampling with immunoassay

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MATRIX: Air samples

ANALYTE: Chlorpyrifos

RANGE OF DETECTION: 0.088 to 1.200 mg/m3

MATERIALS:
Chlorpyrifos RaPID AssayÒ Kit and Sample Diluent. Reagents: methanol (pesticide grade). Equipment: 40 mL glass vials with Teflon lined caps, 13 x 100 mm glass test tubes, 5 mL and 20 mL serological pipets, micropipet (250mL), vortex mixer, and forceps (stainless steel). Air sampling system: Continuous-flow air pump suitable for low volume (1 to 5 liters per minute) sampling, e.g. Model # 224-PCXR8, SKC Inc., Eighty Four, PA or equivalent; polyurethane foam (PUF) sampling cartridges, e.g. Cat. No. 226-92, SKC Inc., Eighty Four, PA or equivalent; tygon tubing for connecting PUF sampling tubes to pump; aluminum foil and clean containers appropriate for handling, transporting and storing sampling tubes. Refer to publications by the Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA) or the National Institute of Occupational Safety and Health (NIOSH) for specific information on air sampling apparatus, assembly and calibration of sampling system, preparation of PUF sampling cartridges and sampling procedures (see References given below). EPA methods TO10 and IP-8 deal specifically with the use of PUF sampling tubes for determination of pesticides in air.

AIR SAMPLING PROCEDURE:
Calibrate air flow of pump to 2 L per minute according to instructions of the pump's operation manual. Place the apparatus in a stationary or mobile location. Mobile positioning of the system can be accomplished by attaching the apparatus to a person to test air in the individual's breathing zone. The pump should run continuously for an 8 hour period to sample one cubic meter of air. At the end of the sampling period, wrap the sampling tube with aluminum foil and place in a sealed, labeled container for transport or storage. Sample tubes should be stored at £ -10°C until analysis.

EXTRACTION OF PUF PLUG:
Remove the PUF plug from the sampling tube using clean forceps (prerinsed with methanol). Transfer the PUF to a 40 mL glass vial containing 20 mL of methanol. Seal the glass vial with a Teflon lined cap. The plug will absorb most of the methanol. Extract the pesticide from the PUF by inverting the vial, so that methanol moves from one end of the plug to the other. Repeat the inversion five or more times to ensure that the methanol has made good contact with the entire PUF plug. Decant approximately 1 mL of the methanol extract into a glass test tube.

ANALYSIS:
Prepare a 1:20 dilution of the extract by carefully transferring 250 mL of the methanol extract from the glass test tube to another glass test tube containing 4.75 mL of the Sample Diluent. Analyze the diluted extract as the 'sample' according to the Chlorpyrifos RaPID Assay package insert.

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