Login / Register | 0 items - $ 0.00 CONTACT US

AlcoPro - Drug and Alcohol Testing Products & DOT Training

  • Products
  • Training
    • DOT Drug and Alcohol Training
    • Employer Substance Abuse Awareness Training
    • Hotels in Knoxville
    • Training Materials
    • DOT Regulations Knowledge Base
  • Knowledge Base
  • Repairs & Services
  • Resources
    • Catalogs
    • Knowledge Base
    • Buyer’s Guide
    • Product Document Library
    • Drug Test Finder
    • Drink Wheel
    • Window of Detection Tool
    • Breath Alcohol Instrument Mouthpiece Chart
  • News
    • News
    • AlcoPro Blog
    • Sign Up – AlcoPro Blog
  • Customer Service
    • Order & Return Policy
    • Shipping Information
    • Apply for Tax Exempt Status
    • Satisfaction & Warranty Policy
    • Repair Services and Technical Support
    • Privacy Policy
    • Customer Reviews
  • Contact Us
    • Contact Us
    • Quote Request
    • Catalog Request
    • Product Sample Request
    • BAC Wheel Request
    • Customer Reviews
  • About Us

800.227.9890

Follow Us on FacebookFollow Us on TwitterFollow Us on LinkedIn

Why Are Drug Test Kits Read Backwards? – Competitive Immunoassay Explained

November 8, 2013 by Jennie Lee-Pace Leave a Comment

On-site drug test kits form a line to indicate the presence or absence of drug in a specimen.  A first-time operator typically expects that the drug test will form a line to indicate a positive result.  It might seem counter-intuitive, but the opposite is true: the presence of a line indicates a negative result.  An understanding of how the kits work may help to explain why the kits are read “backwards.”

 

Drug test kits typically use a technology called “competitive immunoassay.”  Competitive immunoassay describes a process similar to playing musical chairs in which there are more people than chairs.  When the music stops one or more people are left standing because all the chairs are occupied.  In a drug test kit red-colored reagent antibodies compete with any drug in the specimen to attach to a limited number of receptors on the drug test. 

 

When there is no drug in the specimen to compete with the antibodies, all the receptors are occupied by the red-colored reagent antibodies.  When these antibodies bind to the receptors they create a reddish colored line.  The presence of a colored line is read as a negative result. 

 

However, if the specimen contains drugs, the drug molecules compete with the antibodies to bind to the receptors, preventing the antibodies from attaching.  If the red-colored antibodies cannot attach to the receptors they cannot create the colored line.  A test with no line is read as a presumptive positive result.

 

Our shorthand phrase to describe this process is “The presence of drug in a specimen prevents the line from forming.”

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

ABOUT ALCOPRO

Since 1982, AlcoPro has supplied and manufactured the most accurate drug and alcohol testing instruments, kits, and supplies for professional use. We take pride in maintaining our industry-wide reputation for accuracy and quality as we help you—our top priority—perform alcohol and drug screenings and tests with greater precision and confidence.

Subscribe to Our Blog

  • This field is for validation purposes and should be left unchanged.

800.227.9890
Follow Us on FacebookFollow Us on TwitterFollow Us on LinkedInFollow Us on YouTube

Privacy Policy

© 2023 AlcoPro.
All Rights Reserved.

Custom Website Design & Development by VIEO Design