POCT Strips - RT3

Point of Care Test kits (POCT) - Level 1 Certification

ACCURACY AND RELIABILITY of POCTs comes from the strips and how well the user is able to read them. Although POCT strips look like a slice of paper, they are actually a complex diagnostic tool that has been perfected over the past 30 years.

POCT strips

The active element of the testing process


Most POCT strips are similar and have the same basic properties. They all:

  • have test lines that react to target drugs 

  • produce two responses; line or no line.


  • are powered by a chemical reaction.


  • are engineered to a specific cut-off level.


  • are very accurate when used properly

How POCT strips work

POCTs work on the principle that “like particles attract”.  What this means when it comes to drug testing is that a cocaine particle is attracted to other cocaine particles like a magnet.


Each test line is designed to attract a target drug. For example the cocaine test line contains trace amounts of cocaine and will attract cocaine particles in a donor sample. The marijuana test line contains trace amounts of marijuana and will attract marijuana particles in a donor sample. 


When a donor has recently used cocaine and provides a sample, the cocaine in the donor sample will stick to the cocaine on the cocaine test line and will prevent anything else from sticking to the test line. 

The terms Marijuana, THC, and cocaine refer to the target drug for those assays. The Marijuana/THC and cocaine assays are targeting a metabolite. The terms Marijuana/THC and cocaine were used to explain the principle in a basic, non-technical level.

Rapid test strips also contain a reddish colored chemical called colloidal gold conjugate. If you have ever watched a rapid test develop, then you most likely have seen a red dye flowing across the strips. This red chemical is attracted to every test and every control line on the drug test strip.

The parts of a POCT strip

Drug test strips are made up of sections that all work together. 


The TEST LINE is used to identify the presence of a specific drug or drug metabolite in the donor sample. 


The CONTROL LINE is used to identify that specimen is flowing and that the test strips are working properly.


In rapid drug testing, both the drug particles in the donor sample and the reddish chemical (colloidal gold conjugate) are attracted to the test lines. So, when these two particles are present on the POCT strip at the same time, they “compete” for position on the test line. The particles with the stronger attraction will occupy the test line. If enough drug particles are present, the drug particles will prevent the red dye from sticking to the test line.