Advances in Analytical Technology: Deciphering Complex Matrices

With justice and health in the balance, modern forensic toxicology drug testing labs are expected to detect and quantify a wide range of drugs and metabolites, from Fentanyl to novel psychoactive substances (NPS), at very low levels in biological matrices. The drug concentrations also need to be correlated with the impairment of the individual with absolute certainty, but labs face increasing pressures due to growing caseloads, sample backlogs, and budget restrictions.

Urine and blood have been the most common matrices for drug trace analysis for many years. As such, they have well-established data collection methods and are widely accepted for their legitimacy. However, there are challenges associated with these conventional matrices, starting with sample collection, which is an intrusive process, to sample handling procedures that can be time-consuming and hazardous to staff.

For quantitation of drugs in urine, witnessed specimen collection can only be performed by officials of the same gender, which can add further time to the investigation. Conversely, unwitnessed sample collections could be tampered with, so confidence in sample integrity is lost. Blood collections require medical personnel to perform the procedure in order to ensure infection control. Samples therefore need to be collected in designated medical environments - ultimately hindering the timely progress of the analysis.

The ideal sample collection method would be fast, nonintrusive, safe, incorruptible, and easy to perform anywhere. The collection and storage processes need to maintain the integrity of the sample, and there has to be a continuous chain of custody to counteract any possible adulteration.

Alternative complex biological matrices 

In addition to blood and urine, today’s analysts are interested in less conventional biological sample matrices such as hair, oral fluid, breath, and sweat, as they have the potential to increase the reliability, convenience and non-invasive nature of sample collection. Analyzing drugs and metabolites in such alternative matrices also provides a deeper insight into drug metabolism, as well as defining the differences between active and passive drug exposure. While there are several advantages in analyzing such non-conventional matrices, they require highly advanced technologies for robust, reliable, and highly sensitive quantitation assays. Liquid Chromatography (LC) and Gas Chromatography (GC) coupled to Mass Spectrometers (MS) are widely used and recognized platforms for such assays.  

Biological matrices contain various proteins, salts, and phospholipids which can interfere with GC-MS and LC-MS techniques. In addition, these alternative matrices can also pose challenges with regards to limited sample volumes and short windows of detection.

However, with the production of innovative new technologies, tailor-made techniques are being developed to simplify the sample collection and analysis process. Along with these technological advancements, improvements to workflow automation and sample preparation are removing the remaining obstacles to effective analysis of traditional and alternative complex biological matrices.

Solving challenges with advanced technology

Fit-for-purpose sample matrices like hair, oral fluid, sweat, and breath have not previously been viewed as viable alternatives to blood and urine, however these modern advances in analytical technology have enabled them to now come under scrutiny. 

Today, state-of-the-art high resolution accurate mass (HRAM) Thermo Scientific™ Orbitrap™ mass analyzer-based, and triple quadrupole (QqQ) instruments can offer the necessary selectivity with the desirable sensitivity to quantify a host of analytes across a variety of complex matrices. Furthermore, these innovative techniques have achieved unparalleled quantitation in traditional blood and urine matrices. Coupling mass spectrometry with multi-channel based HPLC systems, a laboratory can maximize system utilization by increasing sample throughput up to four times from a single MS and dramatically reduce time consuming sample prep protocols, and the potential for human error.

These triple quadrupole LC-MS/MS and HRAM Orbitrap mass analyzer- based methods provide advantages over alternative techniques such as immunoassays and GC/LC, since they are able to simultaneously screen and identify a broad panel of new drugs and metabolites in a single analysis.

HRAM Orbitrap mass analyzer- based analysis in particular is becoming popular for unknown or untargeted drug identification. This is due to its ability to generate more complete information that allows scientists to re-review data for new substances as they appear, without re-running samples.

The factors that most labs consider when deciding on a testing technique are cost, speed, accuracy, robustness, and ease to perform. Modern instruments that combine these factors are quickly and cost-effectively improving detection accuracy, something this is then further enhanced with the application optimized workflows.