Polymer‐based monolithic column with incorporated chiral metal–organic framework for enantioseparation of methyl phenyl sulfoxide using nano‐liquid chromatography

A new approach to the preparation of enantioselective porous polymer monolithic columns with incorporated chiral metal–organic framework for nano‐liquid chromatography has been developed. While no enantioseparation was achieved with monolithic poly(4‐vinylpyridine‐co‐ethylene dimethacrylate) column, excellent separations of both enantiomers of (±)‐methyl phenyl sulfoxide were achieved with its counterpart prepared after admixing metal–organic framework [Zn₂(benzene dicarboxylate)(l‐lactic acid)(dmf)], which is synthesized from zinc nitrate, l ‐lactic acid, and benzene dicarboxylic acid in the polymerization mixture. These novel monolithic columns combined selectivity of the chiral framework with the excellent hydrodynamic properties of polymer monoliths, may provide a great impact on future studies in the field of chiral analysis by liquid chromatography.     

Novel cyclodextrin chiral stationary phases for high performance liquid chromatography enantioseparation: Effect of cyclodextrin type

Three novel chiral stationary phases (CSPs) were prepared by regioselective chemical immobilization of mono(6^A-N-allylamino-6^A-deoxy)perphenylcarbamoylated (PICD) α-, β-, and γ-cyclodextrins (CDs) onto silica support via hydrosilylation. Their enantioseparation properties in high performance liquid chromatography (HPLC) were evaluated with a large spectrum of racemates including flavanone compounds, β-adrenergic blockers, amines and non-protolytic compounds. The effect of CD's cavity size on enantioseparation abilities was studied and discussed. The results indicated that CD's surface loading at silica support played an important role in the enantioseparation on these CSPs under normal-phase conditions while inclusion phenomena contributed the major driving force under reverse-phase conditions. As expected, α-PICD demonstrated the best resolutions towards flavonone and most aromatic alcohols under normal-phase conditions with the highest surface loading; while Fujimura's competitive inclusion model can be applied to explain the better enantioseparations towards β-adrenergic blockers, amines and non-protolytic compounds with α- and β-PICD CSPs. γ-PICD CSP showed superior enantioseparation ability for sterically encumbered analytes like flavanone compounds under both normal-phase and reversed phase conditions.     

Monolithic metal–organic framework MIL‐53(Al)‐polymethacrylate composite column for the reversed‐phase capillary liquid chromatography separation of small aromatics

A monolithic capillary column containing a composite of metal–organic framework MIL‐53(Al) incorporated into hexyl methacrylate‐co‐ethylene dimethacrylate was prepared to enhance the separation of mixtures of small aromatic compounds by using capillary liquid chromatography. The addition of 10 mg/mL MIL‐53(Al) microparticles increased the micropore content in the monolithic matrix and increased the Brunauer–Emmett–Teller surface area from 26.92 to 85.12 m²/g. The presence of 1,4‐benzenedicarboxylate moieties within the structure of MIL‐53(Al) as an organic linker greatly influenced the separation of aromatic mixtures through π–π interactions. High‐resolution separation was obtained for a series of alkylbenzenes (with resolution factors in the range 0.96–1.75) in less than 8 min, with 14 710 plates/m efficiency for propylbenzene, using a binary polar mobile phase of water/acetonitrile in isocratic mode. A reversed‐phase separation mechanism was indicated by the increased retention factor and resolution as the water percentage in the mobile phase increased. A stability study on the composite column showed excellent mechanical stability under various conditions. The higher resolution and faster separation observed at increased temperature indicated an exothermic separation, whereas the negative values for the free energy change of transfer indicated a spontaneous process.     

Monolithic silica columns functionalized with substituted polyproline‐derived chiral selectors as chiral stationary phases for high‐performance liquid chromatography

In this study, two polyproline‐derived chiral selectors are bonded to monolithic silica gel columns. In spite of high chiral selector coverage, the derivatization was found to have only a slight effect on the hydrodynamics of the mobile phase through the column. The enantioseparation ability of the resulting chiral monolithic columns was evaluated with a series of structurally diverse racemic test compounds. When compared to analogous bead‐based chiral stationary phases, higher enantioseparation and broader application domain were observed for monolithic columns. Moreover, the increase in flow rate produces a minor reduction of resolution, which permits to shorten analysis time. Additionally, increased loadability defines chiral polyproline derived monoliths as adequate for preparative chromatography.     

Preparation of a permethylated β‐cyclodextrin chiral stationary phase by one‐pot hydrosilylation and immobilization at the C2 position for chiral high‐performance liquid chromatography

A novel cyclodextrin intermediate, mono‐2^A‐allylcarbamido‐2^A‐deoxy‐permethylated β‐cyclodextrin, was synthesized by reacting allylamine and newly prepared mono‐2^A‐azido‐2^A‐deoxy‐permethylated β‐cyclodextrin by the Staudinger reaction and anchored onto porous silica beads by a one‐pot hydrosilylation and immobilization procedure to afford a novel chiral stationary phase. This stationary phase acts as a new member of the previous chiral stationary phase series immobilized on the cyclodextrin C2 position. This stationary phase depicted enantiomeric separation abilities toward a series of bicyclic and tricyclic racemates under reversed‐phase conditions. The resolutions for hesperetin and naringenin achieved on the current phase reached 3.91 and 1.11, respectively, much higher than the previous permethylated β‐cyclodextrin with the linkage at the C6 position.     

Gold nanoparticle decorated graphene oxide/silica composite stationary phase for high‐performance liquid chromatography

In the initial phase of this study, graphene oxide (GO)/silica was fabricated by assembling GO onto the silica particles, and then gold nanoparticles (GNPs) were used to modify the GO/silica to prepare a novel stationary phase for high‐performance liquid chromatography. The new stationary phase could be used in both reversed‐phase chromatography and hydrophilic interaction liquid chromatography modes. Good separations of alkylbenzenes, isomerides, amino acids, nucleosides, and nucleobases were achieved in both modes. Compared with the GO/silica phase and GNPs/silica phase, it is found that except for hydrophilicity, large π‐electron systems, hydrophobicity, and coordination functions, this new stationary phase also exhibited special separation performance due to the combination of 2D GO with zero‐dimensional GNPs.     

Evaluation of a novel metal–organic framework as an adsorbent for the extraction of multiclass pesticides from coconut palm (Cocos nucifera L.): An analytical approach using matrix solid‐phase dispersion and liquid chromatography

We report the synthesis, characterization, and application of [Zn(1,4‐benzenedicarboxylate)(H₂O)₂]_n , Zn(1,4‐benzenedicarboxylate)_0.99(NH₂‐1,4‐benzenedicarboxylate)_0.01(H₂O)₂]_n , [Zn(1,4‐benzenedicarboxylate)_0.95(NH₂‐1,4‐benzenedicarboxylate)_0.05(H₂O)₂]_n , and [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n as sorbents for the extraction of multiclass pesticides from coconut palm. Liquid chromatography with ultraviolet diode array detection was used as the analysis technique, and the experiments were performed at one fortification level (0.1 μg/g). The recoveries were 47–67, 51–70, 58–72, and 64–76% for [Zn(1,4‐benzenedicarboxylate)(H₂O)₂]_n , Zn(1,4‐benzenedicarboxylate)_0.99(NH₂‐1,4‐benzenedicarboxylate)_0.01(H₂O)₂]_n , [Zn(1,4‐benzenedicarboxylate)_0.95(NH₂‐1,4‐benzenedicarboxylate)_0.05(H₂O)₂]_n , and [Zn(1,4‐benzenelate)_0.95(NH₂‐1,4‐benzenedicarboxylate)_0.05(H₂O)₂]_n , and [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n , respectively, with relative standard deviation ranging from 1 to 7% (n = 3). Detection and quantification limits were 0.01–0.05 and 0.05–0.2 μg/g, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.01–10.0 μg/g) with r ² > 0.9991. A direct comparison of [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n with the commercially available neutral alumina showed that [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n was a similar extracting phase for the pesticides investigated.     

Enantioseparation tuned by solvent polarity on a β‐cyclodextrin clicked chiral stationary phase

The efficient enantioseparation of 26 racemates has been achieved with the perphenylcarbamoylated cyclodextrin clicked chiral stationary phase by screening the optimum composition of mobile phase in high‐performance liquid chromatography. The chromatographic results indicate that both the retention and chiral resolution of racemates are closely related to the polarity of the mobile phases and the structures of analytes. The addition of alcohols can significantly tune the enantioseparation in normal‐phase high‐performance liquid chromatography. The addition of methanol and the ratio of ethanol/methanol or isopropanol/methanol played a key role on the resolution of flavonoids in ternary eluent systems. The chiral separation of flavonoids with pure organic solvent as mobile phase indicates the preferential order for chiral resolution is methanol>ethanol>isopropanol>n‐propanol>acetonitrile.     

Porous carbon derived from a metal–organic framework as an efficient adsorbent for the solid‐phase extraction of phthalate esters

A porous carbon designated as MOF‐5‐C was prepared by directly carbonizing a metal–organic framework (MOF‐5). The morphology and microstructure of MOF‐5‐C were characterized by scanning electron microscopy, N₂ adsorption, and powder X‐ray diffraction. The MOF‐5‐C retained the original porous structures of MOF‐5, and showed a high Brunauer–Emmett–Teller surface area (1808 m² g^?1) and large pore volume (3.05 cm³ g^?1). To evaluate its adsorption performance, the MOF‐5‐C was used as an adsorbent for the solid‐phase extraction of four phthalate esters from bottled water, peach juice, and soft drink samples followed by high‐performance liquid chromatographic analysis. Several parameters that could affect the extraction efficiencies were investigated. Under the optimum conditions, a good linearity was achieved in the concentration range of 0.1–50.0 ng mL^?1 for bottled water sample and 0.2–50.0 ng mL^?1 for peach juice and soft drink samples. The limits of detection of the method (S/N = 3) were 0.02 ng mL^?1 for bottled water sample, and 0.04–0.05 ng mL^?1 for peach juice and soft drink samples. The results indicated that the MOF‐5‐C exhibited an excellent adsorption capability for trace levels of phthalate esters, and it could be a promising adsorbent for the preconcentration of other organic compounds.     

Enantioseparation of aldols by high‐performance liquid chromatography on polysaccharide‐based chiral stationary phases that bear chlorinated substituents

Two families of aldols, obtained from the condensation of aromatic aldehydes with cyclohexanone or acetone (ten examples in each group), were analyzed by high‐performance liquid chromatography in normal phase elution mode on three polysaccharide‐based chiral stationary phases of the Lux series, namely, Lux Cellulose‐2, Lux Cellulose‐4 and Lux Amylose‐2, which share the common feature of chlorinated substituents in the chiral selectors. Following simple optimization steps, the enantioseparation of all aldols derived from cyclohexanone was achieved and the highest values of separation factor (α, 1.32 < α < 2.20) and resolution (R_s, 4.5 < R_s <17.2) were observed on Lux Cellulose‐2, with the only exception of the 4‐nitro‐substituted derivative that was better resolved on Lux Cellulose‐4. On the contrary, Lux Amylose‐2 was the best choice for aldols derived from acetone and only specific analytes in this group were resolved on the cellulose‐based supports. A variable‐temperature study of selected compounds allowed us to determine thermodynamic parameters of the enantioseparation process, which was enthalpy‐controlled in all the cases except one.     

Chiral stationary phases based on chitosan bis(4‐methylphenylcarbamate)‐(alkoxyformamide)

Highly N‐deacetylated chitosan was chosen as a natural chiral origin for the synthesis of the selectors of chiral stationary phases. Therefore, chitosan was firstly acylated by various alkyl chloroformates yielding chitosan alkoxyformamides, and then these resulting products were further derivatized with 4‐methylphenyl isocyanate to afford chitosan bis(4‐methylphenylcarbamate)‐(alkoxyformamide). A series of chiral stationary phases was prepared by coating these derivatives on 3‐aminopropyl silica gel. The content of the derivatives on the chiral stationary phases was nearly 20% by weight. The chiral stationary phases prepared from chitosan bis(4‐methylphenylcarbamate)‐(ethoxyformamide) and chitosan bis(4‐methylphenylcarbamate)‐(isopropoxyformamide) comparatively showed better enantioseparation capability than those prepared from chitosan bis(4‐methylphenylcarbamate)‐(n‐pentoxyformamide) and chitosan bis(4‐methylphenylcarbamate)‐(benzoxyformamide). The tolerance against organic solvents of the chiral stationary phase of chitosan bis(4‐methylphenylcarbamate)‐(ethoxyformamide) was investigated, and the results revealed that this phase can work in 100% ethyl acetate and 100% chloroform mobile phases. Because as‐synthesized chiral selectors did not dissolve in many common organic solvents, the corresponding chiral stationary phases can be utilized in a wider range of mobile phases in comparison with conventional coating type chiral stationary phases of cellulose and amylose derivatives.     

Incorporation of metal‐organic framework amino‐modified MIL‐101 into glycidyl methacrylate monoliths for nano LC separation

Metal‐organic frameworks consisting of amino‐modified MIL‐101(M: Cr, Al, and Fe) crystals have been synthesized and subsequently incorporated to glycidyl methacrylate monoliths to develop novel stationary phases for nano‐liquid chromatography. Two incorporation approaches of these materials in monoliths were explored. The metal‐organic framework materials were firstly attached to the pore surface through reaction of epoxy groups present in the parent glycidyl methacrylate‐based monolith. Alternatively, NH₂‐MIL‐101(M) were admixed in the polymerization mixture. Using short time UV‐initiated polymerization, monolithic beds with homogenously dispersed metal‐organic frameworks were obtained. The chromatographic performance of embedded UV‐initiated composites was demonstrated with separations of polycyclic aromatic hydrocarbons and non‐steroidal anti‐inflammatory drugs as test solutes. In particular, the incorporation of the NH₂‐MIL‐101(Al) into the organic polymer monoliths led to an increase in the retention of all the analytes compared to the parent monolith. The hybrid monolithic columns also exhibited satisfactory run‐to‐run and column‐to‐column reproducibility.     

Preparation and evaluation of open‐tubular capillary column combining a metal–organic framework and a brush‐shaped polymer for liquid chromatography

In this work, an open‐tubular capillary liquid‐phase column was prepared by modifying chain polymer on the inner surface of capillary and chemical bonding of metal organic frameworks, NH₂‐UiO‐66, to the brushes of chain polymer (poly(glycidyl methacrylate)). Besides advantages of facial preparation and good permeability, the chain polymer effectively increases the modification amount of NH₂‐UiO‐66 nanoparticles to increase the phase ratio of open‐tubular capillary column and enhance the interactions with analytes. The results of scanning electron microscope energy‐dispersive X‐ray spectra indicated that NH₂‐UiO‐66 nanoparticles were successfully bonded to the chain polymer. Because of the hydrophobic interaction and hydrogen bonding interaction between the analytes and the ligand of NH₂‐UiO‐66, different analytes were well separated on the NH₂‐UiO‐66‐modified poly(glycidyl methacrylate) capillary (1.12 m × 25 μm id × 365 μm od) with the high absolute column efficiency reaching 121 477 plates, benefiting from an open‐tubular column and low mass transfer resistance provided by polymer brush and metal–organic framework crystal. The relative standard deviations of the retention time for run‐to‐run, day‐to‐day, and column‐to‐column (n = 3) runs are below 4.28%, exhibiting good repeatability. Finally, the column was successfully applied to separation of flavonoids in licorice.     

Fabrication of ZIF‐8@SiO2 Core–Shell Microspheres as the Stationary Phase for High‐Performance Liquid Chromatography

The unique features of high porosity, shape selectivity, and multiple active sites make metal–organic frameworks (MOFs) promising as novel stationary phases for high‐performance liquid chromatography (HPLC). However, the wide particle size distribution and irregular shape of conventional MOFs lead to lower column efficiency of such MOF‐packed columns. Herein, the fabrication of monodisperse MOF@SiO₂ core–shell microspheres as the stationary phase for HPLC to overcome the above‐mentioned problems is reported. Zeolitic imidazolate framework 8 (ZIF‐8) was used as an example of MOFs due to its permanent porosity, uniform pore size, and exceptional chemical stability. Unique carboxyl‐modified silica spheres were used as the support to grow the ZIF‐8 shell. The fabricated monodisperse ZIF‐8@SiO₂ packed columns (5 cm long × 4.6 mm i.d.) show high column efficiency (23 000 plates m^?1 for bisphenol A) for the HPLC separation of endocrine‐disrupting chemicals (bisphenol A, β‐estradiol, and p‐(tert‐octyl)phenol) and pesticides (thiamethoxam, hexaflumuron, chlorantraniliprole, and pymetrozine) within 7 min with good relative standard deviations for 11 replicate separations of the analytes (0.01–0.39, 0.65–1.7, 0.70–1.3, and 0.17–0.91 % for retention time, peak area, peak height, and half peak width, respectively). The ZIF‐8@SiO₂ microspheres combine the advantages of the good column packing properties of the uniform monodisperse silica microspheres and the separation ability of the ZIF‐8 crystals.     

Analysis of tetracyclines from milk powder by molecularly imprinted solid‐phase dispersion based on a metal–organic framework followed by ultra high performance liquid chromatography with tandem mass spectrometry

A novel molecularly imprinted polymer that could selectively recognize tetracyclines in milk powder was synthesized using a metal–organic framework as a support material, tetracycline as template molecule, and 3‐aminophenylboronic acid as a functional monomer and a cross‐linking agent. The novel molecularly imprinted polymer was characterized by Fourier transform infrared spectrometry, transmission electron microscopy, X‐ray diffractometry, thermogravimetric analysis, and N₂ adsorption/desorption measurements. The adsorption isotherms, adsorption kinetics, adsorption thermodynamics, and selective adsorption experiments of the novel molecularly imprinted polymer to tetracycline were also studied. The novel molecularly imprinted polymer was used as dispersant of matrix solid‐phase dispersion to extraction tetracyclines. After that, the tetracyclines extracted from milk powder were determined by ultra high performance liquid chromatography with tandem mass spectrometry. Under the optimal conditions, the detection limits of tetracyclines were 0.217–0.318 ng/g. The relative standard deviations of intra‐ and interday precision ranged from 3.8 to 6.9% and from 2.8 to 7.4%, respectively. In all three concentration levels (1.0, 10, 50 ng/g), the recoveries of tetracyclines ranged from 84.7 to 93.9%. The method was successfully applied to the determination of tetracyclines in milk powder.     

High‐performance liquid chromatography separation of phthalate acid esters with a MIL‐53(Al)‐packed column

In this study, a MIL‐53(Al)‐packed column was successfully prepared and firstly applied to separate phthalate acid esters (butyl benzyl phthalate, di‐n‐butyl phthalate, diethyl phthalate, bis(2‐ethylhexyl) phthalate, and dimethyl phthalate). Their baseline separation could be achieved within 12 min with a mobile phase of methanol/H₂O ratio at 92:8, and the temperature and flow rate was 40°C and 0.6 mL/min, respectively. The stacking effect and electrostatic force were the key factors in the separation. Moreover, there was a substantial linear relation between the peak height, peak area, and the analyte mass, and the relative standard deviations of retention time, peak height, peak area, and half peak width for five replicate separations of the analytes were within the ranges 0.31–0.88%, 0.72–1.52%, 1.33–1.53%, and 0.46–0.95%, respectively. The results of the calculation of the thermodynamics parameters showed that the separation of phthalate acid esters was controlled by both enthalpy change (ΔH) and entropy change (ΔS).     

Optimized determination of polybrominated diphenyl ethers by ultrasound‐assisted liquid–liquid extraction and high‐performance liquid chromatography

A method based on ultrasound‐assisted liquid–liquid extraction and high‐performance liquid chromatography has been optimized for the determination of six polybrominated diphenyl ether congeners. The optimal condition relevant to the extraction was first investigated, more than 98.7 ± 0.7% recovery was achieved with dichloromethane as extractant, 5 min extraction time, and three cycles of ultrasound‐assisted liquid–liquid extraction. Then multiple function was employed to optimize polybrominated diphenyl ether detection conditions with overall resolution and chromatography signal area as the responses. The condition chosen in this experiment was methanol/water 93:7 v/v, flow rate 0.80 mL/min, column temperature 30.0°C. The optimized technique revealed good linearity (R² > 0.9962 over a concentration range of 1–100 μg/L) and repeatability (relative standard deviation < 6.3%). Furthermore, the detection limit (S/N = 3) of the method were ranged from 0.02 to 0.13 μg/L and the quantification limit (S/N = 10) ranged from 0.07 to 0.35 μg/L. Finally, the proposed method was applied to spiked samples and satisfactory results were achieved. These results indicate that ultrasound‐assisted liquid–liquid extraction coupled with high‐performance liquid chromatography was effective to identify and quantify the complex polybrominated diphenyl ethers in effluent samples.     

Highly efficient high‐performance liquid chromatographic separation of xylene isomers and phthalate acid esters on a homemade DUT‐67(Zr) packed column

In this study, the baseline separations of xylene isomers and phthalate acid esters on a homemade DUT‐67(Zr) packed column were achieved, respectively. The high selectivity for xylene isomers and phthalate acid esters was obtained with the increase in temperature and decrease in the retention time. The hydrophobicity of xylene isomers and phthalate acid esters resulted in the different separation time on the DUT‐67(Zr) packed column. The relative standard deviation values of retention time, peak area, peak height, and half peak width for five repeat separation of the xylene isomers were 0.26–0.35, 2.11–2.26, 1.51–2.03, and 0.29–0.77%, and the values of the phthalate acid esters on DUT‐67(Zr) column were 0.1–0.4, 4.4–5.2, 3.9–6.3, and 0.6–2.1%, respectively. The thermodynamic properties indicated that the separation of xylene isomers was controlled by ΔH and ΔS, but the separation of phthalate acid esters was mainly controlled by ΔS.     

Porous silica particles grafted with an amphiphilic side‐chain polymer as a stationary phase in reversed‐phase high‐performance liquid chromatography

The amphiphilic polymer‐grafted silica was newly prepared as a stationary phase in high‐performance liquid chromatography. Poly(4‐vinylpyridine) with a trimethoxysilyl group at one end was grafted onto porous silica particles and the pyridyl side chains were quaternized with 1‐bromooctadecane. The obtained poly(octadecylpyridinium)‐grafted silica was characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy and Brunauer–Emmett–Teller analysis. The degree of quaternization of the pyridyl groups on the obtained stationary phase was estimated to be 70%. The selective retention behaviors of polycyclic aromatic hydrocarbons including some positional isomers were investigated using poly(octadecylpyridinium)‐grafted silica as an amphiphilic polymer stationary phase in high‐performance liquid chromatography and results were compared with commercially available polymeric octadecylated silica and phenyl‐bonded silica columns. The results indicate that the selectivity toward polycyclic aromatic hydrocarbons exhibited by the amphiphilic polymer stationary phase is higher than the corresponding selectivity exhibited by a conventional phenyl‐bonded silica column. However, compared with the polymeric octadecylated silica phase, the new stationary phase presents similar retention behavior for polycyclic aromatic hydrocarbons but different retention behavior particularly for positional isomers of disubstituted benzenes as the aggregation structure of amphiphilic polymers on the surface of silica substrate has been altered during mobile phase variation.     

Separation of enantiomers of new psychoactive substances by high‐performance liquid chromatography

New psychoactive substances are defined as compounds with consciousness‐changing effects and have been developed simultaneously with classical drugs. They arise through structural modifications of illegal substances and are mainly produced to circumvent laws. Availability is simple, since new psychoactive substances can be purchased from the Internet. Among them many chemical drug compound classes are chiral and thus the two resulting enantiomers can differ in their effects. The aim of this study is to develop a suitable chiral high‐performance liquid chromatography separation method for a broad spectrum of new psychoactive substances using cellulose tris(3,5‐dichlorophenylcarbamate) as a chiral selector. Experiments were performed by high‐performance liquid chromatography in normal‐phase mode under isocratic conditions using ultraviolet detection. Direct separation was carried out on a high‐performance liquid chromatography column (Lux® i‐Cellulose‐5, 3.5 μm, Phenomenex®), available since 2016. Excellent separation results were obtained for cathinones. After further optimization, even 47 instead of 39 out of 52 cathinones showed baseline separation. For amphetamine derivatives, satisfactory results were not achieved. Further, new psychoactive substances from other compound classes such as benzofuranes, thiophenes, phenidines, phenidates, morpholines, and ketamines were partially resolved, depending on the polarity and degree of substitution. All analytes, which were mainly purchased from the Internet, were proven to be traded as racemates.