The role of diode array ultraviolet detection for the identification of synthetic cathinones

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Fentanyl has become pervasive as a drug of abuse and as adulterant in seized drugs. Positional isomers analyzed by gas chromatography with mass spectrometry can follow the same fragmentation pathway and therefore may not be differentiated. Additionally, electron ionization leads to lack of discernible molecular ion for most fentanyl related compounds. Liquid chromatography may be used as an orthogonal identification technique with diode array ultraviolet and mass spectrometric detection. Here we provide a chromatographic method for the separation of 20 different fentanyl analogues, homologues and positional isomers using ultra high performance liquid chromatography with photodiode array ultraviolet and mass spectrometry detection. Five different columns were investigated utilizing reverse phase chromatography and hydrophilic interaction chromatography. Chromatographic systems were evaluated to determine which could separate the most compounds overall, as well as the most positional isomers. We found that isocratic elution, with a methanol modifier (35%) and formic acid (0.1%) as an additive, on a C18 column at a temperature of 25°C could resolve 10/20 compounds overall and 16/20 positional isomers. Using electrospray ionization, compounds with different masses could easily be distinguished based on their pseudo molecular ions. Ultraviolet detection facilitated differentiation of positional isomers that could not be distinguished by either electron ionization or electrospray ionization mass spectrometry alone.

Section: F I G U R E 2 Final Conditions Of Optimized Separation Usingsupporting

confidence: 64%

Analysis of fentanyl derivatives by ultra high performance liquid chromatography with diode array ultraviolet and single quadrupole mass spectrometric detection

Angi

Lurie

Marginean

2019

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“…A representative subset of the separation of the positional isomers using pentedrone and 4‐methylethcathinone is shown in Supporting Information Fig. S1 .…”

Section: Resultsmentioning

confidence: 99%

“…(A) UHPSFC separation of controlled synthetic cathinones Notes: Conditions : injection size, 0.5 μL; column Acquity UPC 2 Torus DIOL. Mobile phase conditions: methanol (10 mM ammonium formate): carbon dioxide (3:97), flow rate 1.25 mL/min; temperature 40°C, applied backpressure regulator 2200 psi; UV detection 215 nm.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, employing a second separation technique in which the separation results are orthogonal to the initial procedure is highly desirable. TLC [7], UHPLC [8][9][10][11], GC [7,12,13], MEKC [14], and ultra high performance supercritical fluid chromatography (UHPSFC) [15,16] have all been employed for the achiral separation of synthetic cathinones, while HPLC [17][18][19], GC [17], CE [20][21][22], CEC [19], and SFC [19] have been utilized for the separation of chiral synthetic cathinones. These studies have been limited in the number of controlled substances and/or positional isomers separated.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones

Carnes

O’Brien

Szewczak

et al. 2017

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A comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones has been conducted. Nine different mixtures of bath salts were analyzed in this study. The three different chromatographic techniques were examined using a general set of controlled synthetic cathinones as well as a variety of other synthetic cathinones that exist as positional isomers. Overall 35 different synthetic cathinones were analyzed. A variety of column types and chromatographic modes were examined for developing each separation. For the ultra high performance supercritical fluid chromatography separations, analyses were performed using a series of Torus and Trefoil columns with either ammonium formate or ammonium hydroxide as additives, and methanol, ethanol or isopropanol organic solvents as modifiers. Ultra high performance liquid chromatographic separations were performed in both reversed phase and hydrophilic interaction chromatographic modes using SPP C18 and SPP HILIC columns. Gas chromatography separations were performed using an Elite-5MS capillary column. The orthogonality of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography was examined using principal component analysis. For the best overall separation of synthetic cathinones, the use of ultra high performance supercritical fluid chromatography in combination with gas chromatography is recommended.

“…Most positional isomers of synthetic cathinones were satisfactorily resolved (resolution ≥ 1) using coupled column UHPSFC [17]. UV detection for LC can distinguish between positional isomers of synthetic cathinones when substitution occurs on the benzene ring [18]. NMR can also distinguish between positional isomers [19].…”

Section: Introductionmentioning

confidence: 99%

The utility of silica hydride‐based stationary phases for dual‐mode ultra high performance liquid chromatography separation of synthetic cathinone positional isomers

Ploumen

Marginean

Lurie

2020

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Emerging drugs usually mimic the effects of traditional drugs, but are not always controlled due to the chemically altered structures. Positional isomers of emerging drugs are difficult to analyze because they challenge the separation and detection techniques commonly employed by forensic laboratories. The utility of silica hydride stationary phases for the ultra‐high performance liquid chromatography separation of synthetic cathinone positional isomers was studied in this manuscript. SiH phases are operable under both reversed phase and aqueous normal phase chromatographic conditions without the need to change solvent reservoirs. The separation of eight positional isomers of the synthetic cathinone, pentedrone, was investigated using five silica hydride phases, and compared to a classical dual column reversed phase, hydrophilic interaction chromatography system, and to a bimodal pentaflurophenyl column. Significant selectivity differences were observed using either a combination of a classical reversed phase C18 and NP Silica columns or the various bimodal columns. The silica hydride silica‐C column, which contains no derivatized ligands attached to the silica hydride backbone, not only gave the most orthogonal separation of the bimodal columns, but provided a unique separation of all eight positional isomers (resolution ≥ 1) using the combination of reverse phase and aqueous normal phase chromatographic conditions.