How Advanced Mass Spectrometry Is Transforming Drug Detection

For years, drug testing has often worked like a checklist. Laboratories look for specific substances, compare the results with a predefined panel, and report what they find. That approach can be highly effective when the substance being sought is known, but what happens when it is not?

As new psychoactive substances continue to emerge and patterns of drug use become increasingly complex, toxicology laboratories are looking for ways to see beyond a limited list of expected compounds. One promising approach is high-resolution mass spectrometry, which can examine biological samples for a much broader range of substances.

Emerging research¹ published in Forensic Science International demonstrates how this technology could expand what laboratories can learn from oral-fluid samples. The work was not designed specifically as a cannabis testing breakthrough. Instead, it examined a broader forensic workflow for detecting new and emerging psychoactive substances. However, the findings have an important implication for cannabis toxicology.

Why Testing Only for THC Provides an Incomplete Picture

When cannabis is involved in a drug-testing program, THC is often the primary target. That makes sense because delta-9-tetrahydrocannabinol is the principal intoxicating cannabinoid and a major marker of recent cannabis exposure. However, a positive THC result does not tell the entire story of what may be present in a person’s oral fluid.

For instance, someone may have been exposed to cannabis alongside another drug, prescription medication, synthetic cannabinoid, or an emerging psychoactive substance. A conventional targeted panel may detect some of these compounds while completely overlooking others if they were not included when the test was designed.

That limitation becomes increasingly important as the drug landscape changes. The question is evolving from “Is THC present?” to “What else is present alongside THC?” That distinction is where advanced mass spectrometry becomes particularly interesting.

How Conventional Oral-Fluid Drug Panels Work

Oral-fluid testing is already useful in forensic and drug testing settings because samples can be collected relatively easily and noninvasively. They can also provide information about relatively recent exposure to drugs.

Traditional testing is commonly performed using a targeted approach. The laboratory establishes which compounds it wants to look for before analyzing the sample. This method can be extremely sensitive and specific for those compounds. The tradeoff, however, is that the laboratory is generally looking for what it already knows to look for. If a newly emerging psychoactive substance is absent from the testing panel, the conventional method may not identify it, thus creating a moving-target problem, as new psychoactive substances can appear faster than laboratories can develop, validate, and add new targeted assays.

What High-Resolution Mass Spectrometry Changes

High-resolution mass spectrometry, or HRMS, offers a broader way to examine a sample. Rather than limiting the analysis to a relatively small, predetermined group of compounds, researchers can collect detailed chemical information and compare it against extensive databases and spectral libraries.

In the study, researchers used liquid chromatography-high-resolution mass spectrometry, or LC-HRMS, to reanalyze oral-fluid extracts that had already undergone routine targeted testing. This is one of the most interesting aspects of the approach, as the researchers did not necessarily need a completely new sample preparation workflow. Existing extracts could be subjected to additional analysis, allowing laboratories to potentially revisit data and search for compounds that were not part of the original targeted testing.

The screening library contained 2,376 compounds, including 1,693 with MS/MS spectra. Researchers also evaluated 105 available reference standards, with 64.8% demonstrating limits of detection at or below 10 ng/mL. That creates something closer to a broad chemical search rather than a simple yes or no test for a handful of drugs.

What Researchers Found in Real Oral-Fluid Samples

The researchers put the workflow to a real-world test using 25 authentic oral-fluid samples. The samples came from three groups: 15 drivers, six chemsex users and four emergency-unit patients. The results demonstrated why broader screening can matter.

LC-HRMS was able to confirm substances that had already been identified through conventional testing, but it also identified additional psychoactive substances that were not included in the routine testing panels. The difference was particularly apparent in the chemsex samples, where the researchers detected a wide range of substances, including numerous new psychoactive substances. The study reported 28 detected compounds in that group, 21 of which were NPS.

And cannabis was part of the picture. THC was detected in seven of the 15 driver samples and two of the six chemsex-user samples. That does not mean the study establishes that cannabis was responsible for the other substances detected, nor does it establish impairment from THC. Instead, it illustrates why a broad-spectrum toxicology approach can provide more information than looking for one compound in isolation.

The Challenge of THC and Other High-Concentration Compounds

Interestingly, THC also illustrates one of the technical challenges researchers encountered. In data-dependent acquisition, the instrument selects ions for additional fragmentation and analysis based on criteria such as their abundance. When a compound is present at a relatively high concentration, it can effectively compete for the instrument’s attention.

That matters because lower-concentration substances may be harder to characterize when abundant compounds are present. The researchers specifically identified THC among the more abundant compounds capable of interfering with detection of lower-concentration substances during data-dependent analysis. This is an important reminder that more advanced technology does not automatically mean every compound will be detected perfectly.

The study’s authors also recognized limitations associated with data-dependent acquisition and noted that low-abundance substances can potentially be missed, particularly when they occur alongside high-concentration compounds.

Implications for Cannabis Consumers and Regulators

For cannabis regulators, forensic laboratories, employers, and impaired-driving programs, the larger implication is not that THC testing is obsolete. It is that cannabis testing could increasingly become part of a broader toxicology picture.

Imagine an oral-fluid sample in which THC is detected. A conventional test might answer that question and stop there. A broader HRMS screening strategy could potentially provide information about whether other psychoactive substances are also present.

The study’s screening library included synthetic cannabinoids and other new psychoactive substances, categories that can be missed by conventional targeted panels when they are not specifically included. This could become increasingly valuable as cannabis products and the surrounding drug marketplace continue to evolve.

For regulators, broad screening could help identify emerging patterns. For forensic laboratories, it could provide additional investigative information. And for impaired-driving programs, identifying multiple substances may help create a more complete toxicological picture, although detecting a substance is not, by itself, proof that it caused impairment.

Why Advanced Screening Still Requires Confirmation

Advanced screening should not be confused with definitive identification in every circumstance. The study describes LC-HRMS suspect screening as a complementary approach, rather than a replacement for targeted quantitative testing. Some findings can reach high identification confidence when supported by reference standards, while others remain presumptive and require additional confirmation.

That distinction is especially important in forensic applications, as broad screening result can flag a substance for further investigation, but laboratories may still need validated targeted methods, reference standards, and quantitative analysis before a result can be treated as a confirmed finding. The technology is therefore best viewed as expanding the laboratory’s field of vision, not eliminating the need for careful confirmation.

The Future of Cannabis Toxicology

The most important takeaway from this research may be a shift in perspective. Drug testing does not have to remain a narrow search for a predetermined list of substances. High-resolution mass spectrometry provides a pathway toward broader screening that can adapt as the psychoactive substance landscape changes. For cannabis testing, that could mean moving beyond the question of whether THC is present and toward a more complete understanding of what may be present alongside it.

The research was fundamentally about forensic toxicology and emerging psychoactive substances, not about creating a new cannabis test. But its cannabis connection is meaningful, as THC appeared in real oral-fluid samples, participated in the complex analytical environment, and existed within a screening workflow that also included synthetic cannabinoids and other emerging substances.

As drug markets become more complicated, that broader perspective could become increasingly important. The future of cannabis-related toxicology may not simply be better at finding THC; it may be better at seeing the whole chemical picture.

References:

^{1. Miriam Blanco-Ces, Rosa Montes, Elena Lendoiro, María Cobo-Golpe, Ángela López-Rabuñal, Angelines Cruz, Ana de-Castro-Ríos, LC-HRMS suspect screening for expanded detection of (new) psychoactive substances in oral fluid: a practical approach for forensic casework, Forensic Science International, Volume 388, 2026, 113102, ISSN 0379-0738, https://doi.org/10.1016/j.forsciint.2026.113102}