Gradient Mode Research Articles

Investigation of the applicability of silica-graphene hybrid materials as stationary phases for capillary liquid chromatography

Graphene and graphene-derived substances are cutting-edge materials receiving increasing attention in the analytical chemistry field. Graphene oxide sheets bonded to amino silica particles functionalized with octadecyl (C18) groups and endcapped, also known as SiGO-C18ec, have been successfully employed as extraction phases and in analytical columns associated with conventional liquid chromatography (LC). In this work, SiGO-C18ec particles of 3, 5, and 10 µm nominal id were employed to pack capillary LC columns (100 mm long x 0.3 mm id), and their performance in the gradient mode was evaluated and compared. A 3 µm C18 capillary LC column (50 x 0.3 mm) was used as a reference column. Eight analytes having different polarities and topological surface areas were selected as a probe in this study: carbofuran clomazone, hexazinone, carbamazepine, citalopram, clomipramine, desipramine, and ochratoxin A. Studies about orthogonality were performed to investigate the orthogonality between the SiGO-C18ec and C18 phases. Among the SiGO-C18ec phases investigated, the column packed with 5 µm SiGO-C18ec particles presented the best peak capacity (29) in 15 min.Additionally, the performance of the columns packed with 5 µm SiGO-C18ec particles overcame the performance of the C18 columns used. Significant orthogonality was found between C18 and SiGO-C18ec packed columns; however, no significant differences were found between columns packed with SiGO-C18ec particles of different diameters.

Sense and nonsense of shifting gradients in on-line comprehensive reversed-phase LC × reversed-phase LC

In on-line comprehensive two-dimensional liquid chromatography (LC × LC), the combination of similar chromatographic modes such as reversed-phase liquid chromatography × reversed-phase liquid chromatography (RPLC × RPLC) usually leads to the partial occupation of the available separation space. A possible solution to circumvent this issue may be to dynamically adjust the gradient elution in the second dimension (2D) throughout the LC × LC analysis. This allows the gradient elution to be tailored to the elution conditions of each fraction instead of using a conventional full gradient program in which the same gradient profile is repeated for each 2D-fraction. In this study, an online RPLC × RPLC method is optimized with shifting gradients in 2D. The logic behind implementing such programs in on-line LC × LC is explained. The optimized method consists of a combination of segmented and shifted gradient modes. It is shown that the retention space coverage can be increased by 50 % compared to a conventional full gradient program, leading to a significant increase in peak capacity (about 35 %). However, such an increase comes at the expense of larger peak widths in 2D and thus lower peak intensities. It is shown here that the use of shifting gradients raises another serious issue related to the repeatability of retention times between two successive 2D-separations.

Development of a generic ultra-high-pressure gradient liquid-chromatography method development protocol: The analysis of residual multi-class antibiotics in food products as a case study

The present study discusses UHPLC method development allowing to establish ultra-high-resolution separations in gradient mode while operating at the kinetic performance limits, targeting the analysis of complex residual multi-class antibiotic samples in food products. The peak capacity and gradient occupation have been systematically assessed at different flow rates and gradient duration. The small particle size (1.5 µm core-shell particles) used in this study limits the mass-transfer contribution to band broadening when operating at high flow rate. As a result, for high-throughput analysis, high-pressure (1500 bar) operation leads to high resolving power where the gradient steepness dominates the peak capacity generation vs mass-transfer resistance. To reach the highest possible resolving power within a practically acceptable analysis time, one should use coupled-column systems at 1500 bar and adjust the gradient steepness correspondingly. Coupling four columns and applying a shallow gradient at 1500 bar led to a sample peak capacity of 379 in 140 min, allowing to resolve 71% of the analytes in a mixture composed of 61 milk antibiotics.

Impact of impurities on drift wave instabilities in reversed-field pinch plasmas.

The drift wave in the presence of impurity ions was investigated numerically in reversed-field pinch plasmas, using the gyrokinetic integral eigenmode equation. By comparing the results of regular and hollow plasma density profiles, it was found that the ion temperature gradient mode for the hollow density profile case is much harder to excite. For the impurity effects, when the impurity density gradient is opposite to the electrons, namely when L_{ez} (L_{ez}=L_{ne}/L_{nz} with 1/L_{n} being the density gradient scale length, and the subscript "e" and "z" indicates electrons and impurity ions, respectively) is negative, the impurities can enhance the instability. On the contrary, when L_{ez} is positive, the instability is stabilized. Regarding the trapped electron mode (TEM), the growth rate for plasmas with a hollow density profile remains smaller than that of the standard density gradient. There exists a threshold in L_{ez}. When L_{ez} is less than this value, the impurities destabilize the TEMs, while when L_{ez} is greater than this value, the impurities stabilize the TEMs. In addition, the influence of the collisionality on the TEMs was also studied.

Ion temperature gradient mode and its solitons with regularized κ-distributed electrons

The linear and the non-linear behaviors of the ion temperature gradient (ITG) mode in a plasma with regularized κ-distributed electrons are investigated using the fluid model. The dispersion relation of the ITG mode obtained on the basis of the local approximation shows that the growth rate of the ITG mode decreases with the increase in the spectral index κ and the exponential cut-off parameter α. It indicates that the presence of the superthermal electron leads to destabilization of the ITG mode, especially in the low κ (κ < 1.5) region. In addition, the existence and the nature of the soliton structure driven by the ITG are studied using the pseudopotential technology. The soliton amplitude increases with the increase in the exponential cut-off parameter α and the spectral index κ, whereas the width of the soliton varies inversely. The present results will help to understand the low-frequency electrostatic wave and nonlinear structure in space and experimental plasmas with non-thermal electrons.

The National Spherical Torus Experiment-Upgrade poloidal high-k scattering system pitch angle design modifications.

A 693GHz, eight-channel, poloidal high-k (k refers to wavenumber) collective scattering system is under development for the National Spherical Torus Experiment-Upgrade device. It will replace the previous 280GHz, five-channel, tangential scattering system to study high-k electron density fluctuations, thereby providing a measurement of the kθ-spectrum of both electron temperature gradient and ion temperature gradient modes. A tool is under development to calculate the wavenumber that exists in the presence of strong magnetic pitch angles. We use this tool to motivate a new receiver optical design for significantly improved performance, details of which are presented herein.

Multi-scale analysis of global electromagnetic instabilities in ITER pre-fusion-power operation plasmas

Global electromagnetic gyrokinetic simulations are performed with the particle-in-cell code ORB5 for an ITER pre-fusion-power-operation plasma scenario, with half-field (2.65 T) and half-current (7.5 MA). We report on a ‘multi-scale‘ analysis of the discharge, considering eigenmodes and instabilities across three scale-lengths (n < 35, 45 < n < 70, n > 100). Although the scenario will nominally have neutral beam heating with particles injected with 1 MeV, Alfvén eigenmodes are investigated in the absence of such source, and reversed shear, toroidal and elliptical Alfvén eigenmodes are found with weak damping for moderately low toroidal mode numbers (10 ⩽ n ⩽ 35). At higher toroidal mode numbers (40 ⩽ n ⩽ 70), unstable Alfvénic modes have been observed close to rational surfaces and are labelled as beta-induced Alfvén eigenmodes (BAEs)/Alfvénic ion temperature gradient modes, since their frequency is associated with the BAE gap and they are driven by the bulk plasma on the Alfvénic continuum. These modes are unstable in the absence of energetic particles (EPs), and adding a species of EPs (with an isotropic 1 MeV slowing down distribution) has negligible impact on their growth rate. At higher toroidal mode numbers (n ⪅ 200), low frequency microscale instabilities are observed.

A new Stability-indicating UHPLC for the simultaneous determination of a combination of Anti-viral drugs: Dolutegravir sodium, Lamivudine and Tenofovir disoproxil fumarate

Dolutegravir sodium, Lamivudine and Tenofovir disoproxil fumarate are anti-viral drugs. A new stability indicating UHPLC method has been proposed for the simultaneous determination of Dolutegravir sodium, Lamivudine and Tenofovir disoproxil fumarate tablets on gradient mode with 1.0mL/min flow rate and a diluent consisting of a mixture of phosphate buffer (pH 3.0) and acetonitrile (62: 38) was used for the study. Shimadzu NexeraX2 Model UPLC system with (PDA detector) Zorbax SB-C18 column (100mm × 4.60mm, 3.5μ) was employed for the present study. Beer-Lambert’s law was obeyed over the concentration range 5-900, 2-700 and 2-150µg/mL with linear regression equationsy = 1724.x-11307 (R² = 0.999), y = 1737.x-1009 (R² = 0.999) and y = 3538.x+587.5 (R² = 0.999) for Lamivudine, Tenofovir disoproxil fumarate and Dolutegravir sodium and the method was validated as per ICH guidelines. The LOQ values were found to be 4.4926, 1.8342 and 1.7963 µg/mL and that of LOD values as 1.4811. 0.6024 and 0.5903µg/mL forD Lamivudine, Tenofovir disoproxil fumarate and Dolutegravir sodium respectively. The combination of Dolutegravir sodium, Lamivudine and Tenofovir disoproxil fumarate was exposed to various stress conditions and the stability of the proposed method was carried out at UV detection 260nm. The proposed UHPLC method is simple, precise, accurate, robust and used for the routine analysis of tablet dosage forms.

New QuEChERS method for quantification of Physalin B and D in Physalis angulata L. in Vietnam

In Vietnam, Physalis angulata L. has been widely used as a traditional medicine to treat fever, anti-inflammatory, and expectorant. Currently, there have been studies on the content of chemical composition especially physalin with anti-diabetic, anti-inflammatory, antibacterial, prevent cancer. This study developed a reliable and sensitive method to determine and validate simultaneous Physalin B and Physalin D in Physalis angulata L.. The QuEChERS method was used for sample preparation from leaf matrices and quantified by using High-performance liquid chromatography coupled with a diode-array detector. The method of research was validated under AOAC and ICH guidance. Chromatography conditions include Agilent C18 column (250mm × 4,6mm; 5µm) with a gradient mode using acetonitrile – methanol-water as mobile phase. The recovery of the method ranged from 94.21 – 105.93% and RSD was from 1.20 – 2.31%, the LOD, and LOQ were 0.4 mg/kg – 2.4 mg/kg, respectively. The results of the study showed that the proposed the new QuEChERS method for quantification of Physalin B and D in Physalis angulata L. in Vietnam.

Global gyro-kinetic study of magnetic shaping effects on linear trapped electron mode instability in normal/reversed magnetic shear plasmas

A linear δf version of the gyro-kinetic Vlasov code GKNET (Gyro-Kinetic Numerical Experiment of Tokamak) is extended to the global cylindrical coordinates (R, φ, Z) and includes the kinetic electron response, to study the shaping effect on linear drift-wave instabilities in Tokamak plasmas. Cross-verifications are performed between three GKNET versions that use different electron models, i.e. the adiabatic electron model, hybrid electron model (only trapped electrons are calculated kinetically) and full-kinetic electron model (all electrons are calculated kinetically). A destabilizing effect of non-adiabatic passing electrons is observed in the full-kinetic case for the ion temperature gradient (ITG) mode in the short wavelength region and the trapped electron mode (TEM). The ion-to-electron mass ratio and the electron–electron collisionality have weak impacts on the destabilization of ITG/TEM. Utilizing magnetohydrodynamic equilibria designed with normal and reversed magnetic shear (NS and RS), the characteristics of linear TEMs and the corresponding impact of plasma shaping are studied based on the GKNET code with full-kinetic electrons. Due to the change in temperature/density gradient and magnetic shear either measured locally in the low field side (LFS) or averaged over the flux surface, plasma shaping shows different impacts on linear TEMs in NS and RS configurations. For the elongation κ, the increase in κ always stabilizes linear TEMs due to the reduction in the effective profile gradient over the flux surface. For the triangularity δ, in the NS case, the change in δ shows weak dependence on TEM linear growth rates due to the balance between variations of profile gradients and magnetic shear in the LFS. In the RS case, local magnetic shear in the peak gradient region is nearly zero. Thus, the variation in local profile gradient plays a dominant role on the linear growth in a plasma shaping scan. Consequently, the negative triangularity (δ < 0) has a destabilizing effect on the linear TEMs in the RS configuration mainly due to the upshift in local profile gradient in the LFS.

A highly sensitive and selective method for the development and validation of potential genotoxic impurity in Raltegravir by high-throughput UPLC-MS/MS

Raltegravir is a human immunodeficiency virus (HIV) integrase inhibitor, a novel anti-AIDS drug. To quantify genotoxic impurities (GTIs), conventional analysis techniques are inadequate as a result, there is a high need to develop critical analytical methods for drug analysis using the hyphenated analytical technique. A highly sensitive and selective method was developed and validated for the estimation of genotoxic impurity in Raltegravir Active pharmaceutical ingredient (API) by using UPLC-MS/MS. The UPLC-MS/MS analysis for the quantification of GTI was performed on the symmetry C18 (150 mm×4.6 mm,3.5μm) analysis column and separation of genotoxic impurity was achieved under a gradient mode system using a mobile phase comprising 1% acetic acid as mobile phase (A) and acetonitrile as mobile phase (B) with a column temperature of 40°C and flow rate of 0.5 mL/min. A triple mass quadrupole detector was used to measure GTI by combining with the negative-electrospray ionization used in multi-response monitoring mode (MRM). The newly developed method was validated as per ICH guidelines and was able to measure GTI at 2.0 ppm for about 10mg/mL solution of Raltegravir. The %RSD obtained for GTI for six preparations was 1.74 in method precision and 2.56 during the variation of analyst, system and column on a different day. The overall %RSD of 2.73 showed the ruggedness of the method. The GTI is linear from 0.039 to 2.9ppm (LOQ to 150%) and R= 0.9998 showed good linearity. The % recovery obtained for genotoxic impurity was in the range 103.0-109.6% with %RSD 1.51-3.19 from 0.42 to 2.5ppm. The %RSD in precision and accuracy at LOQ is 1.63 and 3.19 indicating the sensitivity of the method. The newly proposed and developed high-sensitive method can be used to detect GTI in Raltegravir API and formulation.

Deep Learning-Based Automatic Extraction of Cyanobacterial Blooms from Sentinel-2 MSI Satellite Data

Cyanobacterial harmful algal blooms (CyanoHABs) in inland water have emerged as a major global environmental challenge. Although satellite remote sensing technology has been widely used to monitor CyanoHABs, there are also some automatic extraction methods of CyanoHABs based on spectral indices (such as gradient mode, fixed threshold, and the Otsu method, etc.), the accuracy is generally not very high. This study developed a high-precision automatic extraction model for CyanoHABs using a deep learning (DL) network based on Sentinel-2 multi-spectral instrument (MSI) data of Chaohu Lake, China. First, we generated the CyanoHABs “ground truth” dataset based on visual interpretation. Thereafter, we trained the CyanoHABs extraction model based on a DL image segmentation network (U-Net) and extracted CyanoHABs. Then, we compared three previous automatic CyanoHABs extraction methods based on spectral index threshold segmentation and evaluated the accuracy of the results. Based on “ground truth”, at the pixel level, the F1 score and relative error (RE) of the DL model extraction results are 0.90 and 3%, respectively, which are better than that of the gradient mode (0.81,40%), the fixed threshold (0.81, 31%), and the Otsu method (0.53, 62%); at CyanoHABs area level, the R2 of the scatter fitting between DL model result and the “ground truth” is 0.99, which is also higher than the other three methods (0.90, 0.92, 0.84, respectively). Finally, we produced the annual CyanoHABs frequency map based on DL model results. The frequency map showed that the CyanoHABs on the northwest bank are significantly higher than in the center and east of Chaohu Lake, and the most serious CyanoHABs occurred in 2018 and 2019. Furthermore, CyanoHAB extraction based on this model did not cause cloud misjudgment and exhibited good promotion ability in Taihu Lake, China. Hence, our findings indicate the high potential of the CyanoHABs extraction model based on DL in further high-precision and automatic extraction of CyanoHABs from large-scale water bodies.

Development and validation of stability-indicating -HPLC method for the determination of related substances in novel nitroimidazole antituberculosis drug pretomanid: Robustness study by Design-Expert and application to stability studies.

This study developed a stability-indicating reversed-phase-HPLC method for the determination of related substances of the novel antituberculosis drug pretomanid. Critical quality attributes were evaluated and established for the robust method conditions by using quality-by-design based design of experiments. Forced degradation studies were carried out under acidic, basic, thermal, oxidative, and photolytic stress conditions. Pretomanid degraded when treated under basic conditions, whereas no significant degradation was observed under other stress conditions. The impurities were separated using a Bakerbond C18 column (150 × 4.6mm, 3μm) with the mobile phases 0.1% of orthophosphoric acid and acetonitrile in a time gradient mode. The HPLC method was validated according to the ICH (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) tripartite guidelines. Limit of detection and limit of quantitation of pretomanid and all its impurities were 0.1 and 0.4μg/mL, respectively. The method was found to be linear with a correlation coefficient >0.99, precision (% relative standard deviation < 5.0), robustness, and accuracy (% recovery: 85-115%). Stability studies were evaluated according to the ICH-Q1A, and the drug was were found to be stable in all storage conditions.

Modulational Stability Analysis of Ion Temperature Gradient Mode in Electron-ion Plasma

A theoretical investigation of the modulational stability of the ion temperature gradient (ITG) mode in electron–ion plasma is presented. To examine linear features of dynamic species in plasma, we used reduction perturbation to solve Braginskii’s transportation equations and get phase and group velocities. The results reveal that ion species velocities are affected by plasma factors such as ion temperature, density, and ion temperature gradient coefficient, among others. We also find a nonlinear Schrodinger equation. This equation shows that the plasma dynamics depends on the coefficients of nonlinearity and dissipation of the nonlinear Schrodinger equation. These coefficients are strongly related to the plasma variables. The present investigation may be helpful in space and laboratory plasma, e.g., fusion confinement devices.

Identification and characterization of forced degradation products of sertraline hydrochloride using UPLC, ultra-high-performance liquid Chromatography-Quadrupole-Time of flight mass spectrometry (UHPLC-Q-TOF/MS/MS) and NMR

The present study focused on the forced degradation behavior of sertraline hydrochloride (SRT), selective serotonin reuptake inhibitor (SSRI). The drug was exposed to different stressed conditions (hydrolytic, oxidative, thermal and photolytic) according to ICH Q1A (R2) guidelines. The study revealed that SRT was stable in hydrolytic (acidic, basic and neutral) and thermal degradation conditions. In contrast, five degradation products (DPs) were formed under oxidative and photolytic degradation conditions. The chromatographic separation of drug substance and its DPs was achieved on an Acquity HSS T3 column (100 × 2.1 mm, 1.7 μ) using 0.1% formic acid and acetonitrile as the mobile phase in gradient mode using a UHPLC-DAD system. The DPs were identified and characterized by high-resolution LC/MS and LC/MS/MS in ESI positive mode. Two DPs (DP-I and DP-II) were formed when SRT was exposed to oxidative degradation conditions. Three DPs formed (DP III-V) when exposed to photolytic degradation conditions. All the five major DPs were isolated using Preparative HPLC. The structures of major DPs formed were further confirmed using NMR technique (1D and 2D). The proposed mechanism for the formation of the SRT DPs via the photolytic/oxidative stress degradation pathway are discussed and outlined.

Development and validation of a bioanalytical method for the quantification of axitinib from plasma and capillary blood using volumetric absorptive microsampling (VAMS) and on-line solid phase extraction (SPE) LC-MS

For therapeutic drug monitoring (TDM) of axitinib, the new volumetric absorption microsampling technology (VAMS™) was applied to obtain capillary blood samples in an ambulatory setting and the results were compared to plasma samples as the gold standard. On-line solid phase extraction (SPE) applying a Turboflow HTLC Cyclone™ 1.0 × 500 mm column was used to reduce costs and working time. For the analytical separation, a Kinetex 2.6 µm C18 100 Å, 100 × 3.0 mm column with a flow rate of 0.3 mL/min in gradient mode was utilised. The mobile phase consisted of acetonitrile, water and formic acid (A: 05:95:0.1 v/v and B: 95:05:0.1 v/v). For the detection, a single-quadrupole MS detector was used. Through the use of on-line SPE technology, it is possible to reach a LLOQ of 0.5 µg/L from a 10 µL capillary blood sample. For lower concentrations, a MS/MS-detector coupled with the same chromatographic system was applied reaching a LLOQ of 0.04 µg/L. This newly developed method was validated with both detectors at different calibration ranges for plasma and capillary blood as matrix. The precision of the within- and between-runs was within a range of 0.6–7.8% and 1.8 – 14% CV, respectively, while the accuracy was within a range of 81.2–115% and 87.7–116%, respectively. A reliable, simple, less personnel-intensive and cost-efficient extraction and analysis LC-MS and LC-MS/MS method could be developed and validated, which is applicable in ambulatory and clinical care.

Electron temperature gradient driven transport model for tokamak plasmas

A new model for electron temperature gradient (ETG) modes is developed as a component of the multi-mode anomalous transport module [Rafiq et al., Phys Plasmas 20, 032506 (2013)] to predict a time-dependent electron temperature profile in conventional and low aspect ratio tokamaks. This model is based on two-fluid equations that govern the dynamics of low-frequency short- and long-wavelength electromagnetic toroidal ETG driven drift modes. A low collisionality NSTX discharge is used to scan the plasma parameter dependence on the ETG real frequency, growth rate, and electron thermal diffusivity. Electron thermal transport is discovered in the deep core region where modes are more electromagnetic in nature. Several previously reported gyrokinetic trends are reproduced, including the dependencies of density gradients, magnetic shear, β and gradient of β (β′), collisionality, safety factor, and toroidicity, where β is the ratio of the plasma pressure to the magnetic pressure. The electron heat diffusivity associated with the ETG mode is discovered to be on a scale consistent with the experimental diffusivity determined by power balance analysis.

Ion temperature gradient mode linear and nonlinear structures in electron-ion plasma, with stationary charged dust grain

Ion temperature gradient mode nonlinear structures are studied with stationary charged dust. The dynamical role here is played by heavy ions. The small amplitude limit influence of various plasma parameters shows that the phase velocity of the mode modifies the overall plasma dynamics. Further, from the solution of the model equations we obtain Kortweg-de-Vries (KdV) and Korteweg-de-Vries Burger (KdVB) like equations, the solution of which gives solitary and shock wave nonlinear structures. Numerical analysis of these nonlinear structures shows that dust number density and polarity have a substantial impact on these structures. The present observation may be beneficial in space and laboratory plasma investigations.

Role of secondary long wavelength fluctuation in nonlinear saturation of the kinetic ballooning mode in tokamak plasmas

Nonlinear saturation dynamics of electromagnetic turbulence and associated transport are investigated using a global simulation based on the Landau-fluid model in the finite β tokamak plasmas. The focus is on the kinetic ballooning mode (KBM), while a comparison to the β stabilized ion temperature gradient mode is carried out. Results show that the KBM turbulence creates relatively weaker zonal flows in finite β plasmas. Zonal current could be formed around the low order rational surfaces, but is too narrow and localized to affect the global transport level. It is found that the KBM turbulence is nonlinearly saturated in two sequential stages. The linear KBM instability is first saturated transiently at a low fluctuation level by weak zonal flows. Afterward, robust, linearly stable long wavelength fluctuations are nonlinearly excited and then interact feedback with primary unstable KBM components through the modulation process. As a result, the KBM is finally saturated with a down-shifted wavenumber spectrum. The suppression of turbulent transport by long wavelength fluctuations is identified as mainly resulting from the reduction of KBM turbulence intensity.

Targeted and untargeted screening of new psychoactive substances (NPS) and classical drugs of abuse in Paris using hair testing: A 10-years study (2012–2021)

To detect and quantify NPS and conventional drugs of abuse (DoA) between 2012 and 2021 in high-risk populations of Paris area, and to describe their characteristics using hair testing based approch and a combination of targeted and untargeted screening by LC-MSMS and LC-HRMS. In all, 939 hair samples collected in addiction ( n = 229, 24%) or intoxications ( n = 337, 36%) settings were segmented whenever possible (A: 0–2 cm; B: 2–4 cm; C: 4–6 cm) and analyzed using a previously published LC-MS/MS and LC-HRMS methods dedicated to the screening of DoA and NPS in hair. Briefly, 20 mg of hair was washed with dichloromethane, dried at room temperature and pulverized. It was hydrolyzed in phosphate buffer (pH 5.0, 95 °C, 10 min) and extracted using hexane/ethyl acetate and chloroforme/isopropanol. Separation were performed in a gradient mode using Hypersil PFP Gold column (100 mm × 2.1 mm, 1.9 μm) for targeted screening and Phenyl hexyl column (100 mm × 2.1 mm, 1.9 μm) for untargeted screening. Triple Quad TSQ Altis in MRM mode and Q Exactive Orbitrap in ddMS2 mode (both from ThermoFisher®) were used as detection systems. NPS were detected 1551 times in 288 cases. Their prevalence was 31% and was lower than that of amphetamines (34%), cocaine (42%) or licit/illicit opioids (51%) measured in the same populations. Consumers were predominantly male (68%) with a median age of 30 years. 51 different NPS were detected with 1 to 15 NPS being consumed per patient within the same period: ketamine (n = 84, 54 pg/mg median), mephedrone (26, 100), dextromethorphan (16, 100), normephedrone (9, 1630), 4-MEC (6, 205), methylone (5, 20), ethylphenidate (5, 9), 3-MMC (5, 330), flubromazepam (4, 192), etizolam (4, 5), α-PVP (4, 67), α-PHP (4, 5895), N-ethylpentylone (4, 50), 5-APB (3, 255), 3-FPM (3, 583), harmine (2, <1), mitragynine (2, <1), MDPV (2, 55), pentylone (2, 9), 2F-DCK (2, 3260), O-PCE (2, 20), 4-FA (2, 560), m-CPP (2, 569), 5F-AKB48 (n = 2, 16), 5F-PB-22 (2, 12), DMT (2, 7), 5-MeO-DMT (2, 5), 3/4-MeO-PCP (2, <1), and one case respectively for N-methyl-2-AI (326 pg/mg), 5-EAPB (60), clonazolam (24), metizolam (4), 4F-PHP (<1), 4-MePPP (10,000), butylone (68), ethcathinone (23,292), DCK (1500), MXE <1), ephenidine (190), 25C-NBOme (2), 25I-NBOme (15), AB-FUBINACA (22), ADB-PINCACA (10), AM-2201 (10), BB-22 (10), CP 47497-C8 homolog (< 1), JWH-019 (27), JWH-200 (13), JWH-250 (40). 4-HO-MiPT and isopentedrone were not quantified (lack of reference standards). Hair concentrations have allowed to distinguish occasional from chronic users. To our knowledge, this is the most comprehensive study based on hair testing demonstrating the use of different types and levels of designer drugs in Paris metropolis from 2012 to 2021. Their prevalence appears to be significant and understated as they are not systematically sought by laboratories.