Tuesday, August 18, 2009

EMIT - Enzyme-Multiplied Immunoassay Technique

What is EMIT?

E- Enzyme

M- Multiplied

I- Immunoassay

T- Technique

Emit is:

  • cheapest and simplest technique
  • an analytical method used in Clinical Toxicology
  • commonly used in screening blood (serum) for TDM (Therapeutic Drug Monitoring) and as a primary screening procedure of abused drugs and their metabolines in the urine.
  • it is the first homogenous assay to be widely used.
  • the separation using antibody specificity (antigen binding).
  • measurement of enzyme-substrate reactions using visible spectroscopy, and standard curve.
  • produces reliable results
  • the test utilizes antibodies that are enzyme linked and react only with the specific substance in the sample(urine or blood) is positive with the particular drug being tested.

Components of the Assay & Principle:

  • drug in the specimen (urine/serum)
  • Ab -- Antibody
  • Ag -- Antigen
  • substrate
  • enzyme labeled antigen
  • enzyme bound to drug
  • reagent enzyme Ag
    Ag being measured competes for the Ab binding sites with the antigen that has been labeled with an enzyme ---->the antibody reagent blocks any enzymatic activity when it is bound with the reagent enzyme Ag complex (thus preventing the formation of the product with a substrate) ----> then the free Ag-enzyme complexes compete with the Ag (in the sample) ----> forming a color change which are proportional to the concentration of the Ag present in the tested sample.

    References: Clinical Laboratory Diagnosis by Henry et. al.


  1. So, can someone really get a false positive for opiates by eating a poppy-seed roll or two for breakfast?

  2. Nera,

    We have a question from Holly. Kindly answer it. Thanks.

    Cite references please.

  3. A cheap and simple technique which gives highly reliable and accurate results is a good thing.

  4. Nera,

    I think Holly's question was featured in the Mythbusters!

    Interesting post.

    Keep it up!


  5. Cheers!
    Great post! Very informative.
    Thanks for possibility to write on your website,
    it's great!
    I’m still hoping there will be more posts on this site.
    Thanks a lot!

    multiplex immunoassay

  6. Can EMIT be done through Strip Tests, OR can it to be done in a Laboratory by Machine only ??