Re: How to measure concentration level of House Dust Mite Allergen?

Scientists use a machine called a Biosensor which consisit of a round 
selectively permeable membrane ( acetyl cellulose ) and coated on a 
chip, which consist of two layers , the Biological recognition layer and 
transducer which feeds imformation to a computer.
Reference Dictionary of Biology , Kane and Horne
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Madministrator additional notes:

Here is an article where they measured the concentration of Dust Mites in 
mattresses:

http://ehp.niehs.nih.gov/members/1998/106p659-664hirsch/hirsch-full.ht
ml

"Sampling Procedure 

Carpets (1 m2) and children's mattresses (1.6 m2, covers removed) were 
vacuumed for 5 min with vacuum cleaners with a motor capacity of at least 
800 W by residents following written instructions (study 1) or by trained 
field workers (study 2).
Dust was collected with a sampling device (ALK, Copenhagen, Denmark) 
holding a cellulose filter (Filtrak GmbH Niederschlag, Germany, no. 60; 
0.35 mm thick, pore size 30-40 µm), which retains 98% of particles >0.7 
µm in diameter and 91% of particles >0.3-0.7 µm. 

Laboratory Analysis 

Samples were weighed and processed unsieved (allergen extraction 
from dust and filter paper) to allow the determination of total allergen 
amount. The concentration of HDM allergens Der p 1 and Der f 1 was 
determined with a commercial sandwich ELISA (ALK). The results were 
expressed as allergen concentration (microgram per gram of dust) and 
as amount of surface allergen (microgram per square meter). The 
intra-assay CV determined by the manufacturer was 4.1-19.9%. The 
interassay CV determined in our laboratory by positive control samples on 
every plate ranged between 9.2% and 16.6% (Der p 1) and 14.9% and 
16.5% (Der f 1). Assay sensitivity was 3 ng/ml or 0.03 µg/g dust. "

Here is a description of the "commerical sandwich ELISA" mentioned in 
that article:

Sandwich ELISA ( Enzyme-linked Immunosorbent Assay )

The sandwich ELISA measures the amount of antigen between two layers 
of antibodies. The antigens to be measured must contain at least two 
antigenic sites, capable of binding to antibody, since at least two 
antibodies act in the sandwich. So sandwich assays are restricted to the 
quantitation of multivalent antigens such as proteins or polysaccharides. 
Sandwich ELISAs for quantitation of antigens are especially valuable 
when the concentration of antigens is low and/or they are contained in 
high concentrations of contaminating protein.

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http://research.cm.utexas.edu/bkitto/Kittolabpage/Protocols/Biochemistry/
sELISA.html


Here is a brochure on ELISA:
http://www.kpl.com/docs/techdocs/chapters%201%20-%204.pdf