Application Guide—Rapid Detection of Fentanyl in Urine Using the OPSI Open Sampling Port in Combination with the expression CMS

Globally, healthcare professionals and law enforcement agencies have a strong demand for rapid and simple analytical methods to detect drug abuse. In 2017, fentanyl had become the most widely abused synthetic opioid—and had even emerged as a public health concern. Fentanyl is a rapidly synthesized painkiller with an analgesic potency nearly 100 times that of morphine.

As market demand continues to grow, AIS has developed a simple and rapid urine fentanyl screening method—combining the Touch Express OPSI open sampling port with the expression CMS compact benchtop mass spectrometer to enable swift screening.

The OPSI open sampling port technology, upgraded and developed from the AIS ESI electrospray ionization source, provides a rapid detection solution.

Experimental method

Fentanyl (1.0 mg/mL) and fentanyl-d5 (100 µg/mL) as standard solutions.

Standard solutions at concentrations of 2.5, 5, 10, 25, 50, 100, 250, 500, and 1000 ng/ml; Fentanyl-d5: 100 ng/ml—use these to plot the calibration curve.

Next, the samples were prepared using liquid-liquid extraction (LLE). To 0.5 mL of urine sample, 1.5 mL of a 1:1 ethyl acetate/hexane mixture was added, vortexed for 20 seconds, and allowed to stand for 2 minutes. Then, 1.0 mL of the supernatant was transferred to a clean 2-mL centrifuge tube and evaporated to dryness in a vacuum evaporator. The dried extract was reconstituted with 250 μL of methanol, after which it was subjected to OPSI-CMS analysis.

The solvent is delivered to the open sampling area at a flow rate of 250 µl/min. Under the influence of the Venturi effect, the solvent forms a meniscus at the opening, and the sample flows along the tubing into the ion source of the mass spectrometer. Control and fentanyl-spiked urine samples are sequentially introduced to the Touch Express sampling port (Figure 1), and results are obtained within less than 30 seconds.

Experimental results

Mass spectra of fentanyl and fentanyl-D5: The hydrogenated peaks of fentanyl and fentanyl-D5 were detected at m/z 337.2 and 342.2, respectively. These ions at m/z are used for quantitative determination of fentanyl in urine during selective ion monitoring (SIM).

SIM analysis of fentanyl in urine: After purification of the fentanyl-free control urine by LLE, no interference was detected at the SIM m/z. The extracted ion chromatograms (XICs) for the control urine are shown in Figure 3a. The XIC for fentanyl-D5 is shown in Figure 3b.

Simultaneous analysis of fentanyl in urine by SIM, at 2.5 ng/mL (Figure 4A), and fentanyl-D5 by SIM, at 100 ng/mL (Figure 4B): The signal-to-noise ratio (S/N) for 2.5 ng/mL fentanyl was 135, indicating that the estimated limit of quantitation (S/N = 10) is below 1 ng/mL. The total analysis time per sample was less than 30 seconds. No carryover was observed, demonstrating that OPSI has the capability for high-throughput screening of fentanyl.

The calibration curve showed a linear regression correlation coefficient of 0.997, with a linear dynamic range from 2.5 to 500 ng/mL.

Within the concentration range of 2.5 to 500 ng/mL, the measured average accuracy and precision (CV%) were 87.5 ± 0.17% to 106.5% ± 3.36%, respectively, within the specified standard range.

Conclusion

Touch Express OPSI Open Sampling Port is a unique sampling technology that offers operators a quick and easy solution:

1. It can be applied to fields such as drug research, food safety, environment, and forensic science;

2. It can be used for the detection of macromolecular substances, such as proteins, lipids, nucleotides, polymers, and others.

3. Both solids and liquids can be directly injected without the need for sample pretreatment, and experimental results can be obtained in just 30 seconds.

4. An economically efficient, high-throughput detection technology.

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