A video demonstration of the surface wipe sampling method tutorial. The surface wiping procedure followed the methods previously published by our group. All wipe sampling supplies, along with written instructions, are provided in a standardized toolkit and delivered prior to sampling dates. The supplied 10 cm x 10 cm plastic template is to be placed on the selected surfaces to demarcate the area for sampling. Irregular surfaces like doorknobs can be measured using the supplied flexible ruler for surface area calculations. The area within the template is sampled for contamination by wiping vertically and then horizontally, folding the prior to switching directions filter.
The complete procedure is as follows:
- Remove boxes containing wipe sample vials from the soft cooler and place on a clean tray or cart. Set cooler aside for the end of sampling.
- Remove bag containing clean tweezers, rulers, and masking tape from the soft cooler and place on clean tray or cart.
- Find “OEH Lab Sample Submission Form” and place on clean tray or cart.
- Using the form, identify the next surface for sampling.
- Put on your gloves. Avoid unnecessary touching of the target surface. Ensure that the gloves fit properly – excessively large gloves may make it difficult to handle the wipe.
- Remove the next vial from the box. Compare the sample ID of the vial to the sample ID listed on the Wipe Sampling Form and make sure that they match.
- For flat surfaces, place the demarcation template on the surface to define your sampling area. Tape the edges of the template to secure it in place. For non-flat surfaces/objects, take measurements with the included ruler and record the dimensions in the sampling form. Where possible, try to obtain a sample area of 100 cm2.
- Remove a wipe from the vial. Use one prong of the provided tweezers to pull the wipe partially out of the vial. Set tweezers down in clean area and fully remove wipe from vial.
- The wipe should already be folded in a manner suitable for wiping when removed from the vial. Grasp wipe so that the wider side is used for wiping.
- Applying moderate pressure (enough to feel a little resistance to the movement of the wipe, but not enough to tear the wipe), wipe the surface with a top to bottom motion (vertical) ensuring that the entire template area is wiped (see figure 1).
- Then fold the wipe in such a manner so that the wiped area is on the “inside” of the fold, attempting to not touch the wiped/contaminated area of the wipe with your glove.
- Repeat the wipe sampling in a left to right motion (horizontal, see figure 2).
- If there is any visible residual solvent from the previous left to right wiping, finish with one last wipe down the right side of the template.
- Fold or roll the wipe so that it can fit back in the sample vial, insert it, and cap the vial.
- Place the vial back into the sample box.
- Remove your gloves in the standard way to avoid self-contamination and dispose of them appropriately.
- Wash your hands (as required by local protocols). Document any notes about sample/surface in Wipe Sampling Form.
- Repeat steps for additional surfaces/objects.
- Return the sample box to the cooler. If samples are to be stored overnight before shipment, it is recommended that the samples be stored in a refrigerator or freezer.