Roadside/Field Drug Test Kits
Roadside drug test kits or color-based field kits contain chemicals intended to react to suspected substances to create a color change when in the presence of a narcotic. False positives occur because the chemicals target specific aspects of the suspected narcotic and not the narcotic itself. These aspects of narcotics have commonalities with other everyday items as innocuous as soap, chocolate or sugar substitutes. Hence, these tests have an inherent inaccuracy and so will frequently give a false positive result.
The companies that manufacture and sell these tests recognize that inaccurate results will occur. That is why roadside drug test kits state on their packaging that additional laboratory testing is necessary to confirm the presence of a narcotic.
Electronic Field Test Device
In contrast, portable, electronic field test devices using technologies such as mass spectrometry or Raman spectroscopy highlighted in the National Institute of Justice study generally have the ability to target and accurately detect specific narcotics. They use various chemistries to isolate and detect the specific targeted compounds for identification. Just as each person has a unique fingerprint pattern, these instruments can identify the fingerprint of particular drug substances, and compare the sample to known reference materials (e.g. the reference standard for cocaine). This creates a direct comparison of the sample material to the particular narcotic, providing accurate verification when the correct testing protocols are followed.