Validation of Colorimetric Field Tests for Drug Detection

OVERVIEW

The National Institute of Standards and Technology (NIST) has partnered with AOAC INTERNATIONAL to address the need for standards development for colorimetric “spot” or “color” field tests used to detect drugs in solids, residues, and, where applicable, liquids. The standards to be developed include a Standard Method Performance Requirements (SMPR^®) document as well as a companion standard method validation protocol for colorimetric field-test methods used for this purpose. The initial set of targeted analytes for detection includes fentanyl and other opioids, cocaine, heroin, methamphetamine, MDMA, and ketamine.

BACKGROUND

Colorimetric spot tests are long-established presumptive techniques valued by law enforcement, border security, and forensic personnel for their simplicity, low cost, and rapid results. However, because these tests rely on a human operator’s interpretation of a color change, independent reviews have raised significant concerns regarding their selectivity, sensitivity, and reliability. Because a presumptive result can carry significant real-world consequences, reliable and validated method performance standards are needed to support consistent, defensible field use.

This initiative builds directly on a closely aligned collaboration completed in December 2025, in which AOAC partnered with NIST to develop and publish AOAC SMPR 2025.002 and the companion standard method validation protocol AOAC SP 2025.001 for the field-based detection of benzodiazepines, fentanyl, medetomidine, nitazenes, and xylazine. That successful project demonstrates both AOAC’s established working relationship with NIST and the proven applicability of AOAC’s standards development process to this type of drug field-testing challenge.

NEXT STEPS

To begin this work, AOAC will partner with NIST to convene an advisory panel (AP) to establish the scope of the standards (fitness-for-purpose statement) and the intended use of the methods. Once the AP is formed, AOAC will recruit experts from industry, government, academia, and other sectors to form and launch a technical working group (WG) responsible for drafting the proposed standards.

Based on the current understanding of this work, we envision two standards to be developed. First, an AOAC Standard Method Performance Requirements (SMPR^®) document specific to colorimetric field tests for drug detection will be created. The draft SMPR will provide method performance requirements and requirements for validation such that, once the draft SMPR is consensus approved, AOAC will engage a subset of the WG to develop a second standard — a companion standard method validation protocol for the validation of colorimetric field-test methods.

The AOAC INTERNATIONAL standards development process is based on a transparent process incorporating a diverse membership of volunteers as well as a public comment period, to ensure that all perspectives of expertise are considered. Both standards will be published and may be used by method developers and authors to determine whether a candidate method meets the SMPR through the application of the validation protocol. These standards may also serve as a guide to inform end users on the expected acceptable performance and scientific scrutiny for such rapid tests, providing a benchmark for methods specific to this application.

After completion of this grant, AOAC will invite method developers to apply to the AOAC Performance Tested Method^SM (PTM) program and validate their methods via these standards, based on the needs of end users and method development organizations. The AOAC PTM program conducts an independent, third-party review of commercially available, proprietary methods validated according to the appropriate protocol, with a goal of formal AOAC method certification.