Asbestos in Wipes / Swabs samples
To detect, classify, identify, and determine density of asbestos in surface sampling of settled dust.
Settled dust / Surface sampling
Wipe/swab samples can be analysed via TEM using the ASTM D6480 method. This method allows the analyst to deliver a quantitative result for a bulk sample.
The preparation involves placing the entire sample into an ultrasonic bath filled with a mix of water and acetic acid to release all potential fibres into the solution. This solution is then filtered onto a polycarbonate membrane and finally deposited on TEM grids for analysis.
Sampling involves using non-woven wipes saturated with 70% isopropyl alcohol (avoid ghost wipes). The sampling procedure is described in section 9 of ASTM D6480. The standard surface area to wipe is about 100 cm² (a square template of 10×10 cm). The surface area sampled is needed to calculate the concentration.
Objectives of the analysis
- Identify potential contamination issues
- Determine the type of asbestos
- Locate additional sources and identify hot-spots
- Initiate air sampling to ensure occupant safety
Interpretation
Guidance Method ASTM D7390, or :
