Procedures for Preparation of Dust Samples for Allergen Determination

A. Collecting Dust Samples
B. Submitting Dust Samples
C. Extracting Dust Samples (procedure carried out at Indoor Biotechnologies, prior to analysis for allergen content)

Collecting Dust Samples

1. Insert the plastic filter into the MITEST collector and attach the collector to the vacuum cleaner tube.
   
   
2. Turn on the vacuum cleaner and vacuum 4 separate areas (approximately the area of a letter-size sheet of paper) for 30 seconds each (total sampling time, 2 minutes; total area sampled ~0.25sq meter)
   
   
3. Remove the filter containing the dust samples and place it in a small Ziploc bag or envelope.
   
   
4. Rinse the MITEST collector with water, place a clean filter inside the collector for repeat sampling.

* Two caps are provided with the MITEST collector system. These caps enable dust to be extracted with buffer within the collector and are designed for use with our rapid dust mite test. These caps can be used to prepare extracts on site if necessary, but do not need to be used for samples submitted for our INDOOR® Allergen Analysis Service.

Submitting Dust Samples to INDOOR®

1. Fill out the Analysis Request Form completely and indicate which tests are requested.
   
   
2. Submit the samples to the INDOOR® Allergen Analysis Service Lab in an air tight Zip-lock bag or a sealed plastic vial with the sample numbers clearly marked on the bag with a permanent marker.
   
   
3. Ship Samples to:

   Indoor Biotechnologies, Inc. **
   Attn: INDOOR® Allergen Analysis Laboratory
   1216 Harris Street
   Charlottesville, VA 22903

   ** For countries other than North and South America please send samples to:

   Indoor Biotechnologies, Ltd.
   Attn: INDOOR® Allergen Analysis Laboratory
   The Old Brewery
   38, High Street
   Warminster Wiltshire, BA12 9AF
   United Kingdom

Extracting Dust Samples

1. Sieve dust through a No. 45 mesh screen, 355µm diameter (VWR No. 57332146) to remove large particles and fibers.*
   
   
2. Weigh 100 mg (±5mg) fine dust into a 75mm x 12 mm plastic test tube (Sarstedt No. 55.476).
   
   
3. Add 2.0ml PBS-T (0.05% Tween 20 in phosphate buffered saline, pH 7.4). For samples between 30mg and 100mg add the proportional amount needed. Samples <30mg are labeled as "Not Enough Sample" and not processed.
   
   
4. Resuspend using a vortex mixer (Vortex-Genie, Fisher Scientific).
   
   
5. Mix end over end for 2 hours on an laboratory rocker (Labquake Shakers, Fisher Scientific, Cat# 13-687-17) at room temperature.
   
   
6. Centrifuge 20 minutes at 2,500 rpm 4°C.
   
   
7. Remove supernatant (approximately 1.5ml) with a Pasteur pipette, for measurement of antigen. Discard dust pellet.
   
   
8. Store extract (supernatant) at -20°C in a freezer vial with sample number or relevant code clearly labeled for future analysis of allergen content.

*Whether to sieve the dust or not is determined by the quality of the dust. We do not routinely sieve dust collected from beds and soft furnishings. Carpet samples are sieved (e.g. using a No. 45 mesh screen, 355µm diameter sieve) to separate the fiber and large particles from fine dust.

We recommend the use of the MITEST dust collector which greatly reduces the need for sieving dust. After collecting a dust sample using the MITEST dust collector, remove the nylon filter containing the dust sample insert, invert the filter and tap the dust onto a piece of weigh paper. The fine dust falls before the fibers come out of the filter.