Organic Mobile Phase Research Articles

Novel Quantitative Estimation of Rucaparib and Bevacizumab in Rat Plasma Using LC-MS/MS & Study of Pharmacokinetics.

Rucaparib and Bevacizumab‘s bioanalytical evaluation was performed using an easy-to-use, effective, and repeatable LC-MS/ MS technique, with D6-Rucaparib and D6-Bevacizumab serving as internal standards. This work provides a summary of current developments in bioanalytical LC-MS/MS techniques using an organic mobile phase consisting of 50:50 formic acid and acetonitrile IN 0.1% as well as a Waters Symmetry C18 column. The results for stability, matrix effect, accuracy, precision, and recovery were all within allowable bounds. To test the targeted analytes in body fluids using pharmacokinetic research, a simple and efficient approach was created. This application included all accuracy, system appropriateness, linearity, and specificity characteristics that were used successfully for pharmacokinetic investigations in rats and that complied well with USFDA guidelines.

Liquid Chromatography Coupled to Isotope Ratio Mass Spectrometry Expanded to Include Organic Mobile Phases.

Current commercially available liquid chromatography coupled to isotope ratio mass spectrometry systems (LC-IRMS) oxidize all eluent and thus can only operate with all-aqueous mobile phases, limiting their application to a small subset of analytes and mixtures that can be separated without organic solvents. We report a novel rotating-catalytic disc desolvation device with subsequent laser-activated photocatalytic analyte combustion to create CO2 for high precision carbon isotope ratio measurements compatible with both aqueous and organic liquid mobile phases. Sucrose, glucose, androsterone, or androsterone acetate in 20% and 50% H2O-CH3OH solutions were introduced by flow injection to the interface to IRMS for sugars and steroids, respectively. Sucrose δ13CVPDB linearity was excellent over 1-10 μg (33-655 nmol C) injections, using IRMS compatible He/1%O2 oxidation gas. The limit of precise isotope analysis (LOIA) of δ13CVPDB was 1 μg (35 nmol C) for sucrose and 10 μg (655 nmol C) for androsterone with average precisions of SD(δ13C) ± 0.8‰. Calibration was performed with and bracketed the δ13CVPDB isotope ratio range using androsterone-acetate and glucose. With further development to improve sensitivity and application to chromatography, the prototype proof-of-principle LC-IRMS shows promise to resolve a major drawback in current LC-IRMS systems and may open LC-IRMS to many more compounds than currently possible.

Whiter and Greener RP-HPLC Method for Simultaneous Determination of Dorzolamide, Brinzolamide, and Timolol Using Isopropanol as a Sustainable Organic Solvent in the Mobile Phase

A sustainable reversed-phase chromatographic method has been developed and validated for the simultaneous determination of three active pharmaceutical ingredients, dorzolamide, brinzolamide, and timolol, used to treat glaucoma. The eco-friendly solvent isopropanol has been used as an organic mobile phase constituent. According to the Hansen space green solvent selection tool, isopropanol has a G score of 6.5, comparable to ethanol, which has a G score of 6.6. The mobile phase consists of isopropanol: aqueous sodium acetate buffer (0.1 M, pH 4.25) in the ratio of 10:90 (v/v). The flow rate was maintained at 1 mL/min. Dorzolamide and brinzolamide were detected at 254 nm, and timolol was detected at 295 nm. A high-purity silica with a polymeric C18 modification column (150 × 4.6 mm, 5 µm particle size) was used for this separation. The three compounds were eluted within 8 min. The method was validated according to ICH guidelines. The calibration curves were linear in the range of 20–70 µg/mL, 40–140 µg/mL, and 20–70 µg/mL for dorzolamide, brinzolamide, and timolol, respectively. The LODs were found to be 1.61 µg/mL, 1.60 µg/mL, and 3.16 µg/mL for dorzolamide, brinzolamide, and timolol, respectively. Good accuracy and precision were obtained for the three compounds. The greenness and whiteness of the method were indicated using the AGREE, ChlorTox, and RGB12 tools.

Therapeutic Monitoring of Palbociclib, Ribociclib, Abemaciclib, M2, M20, and Letrozole in Human Plasma: A Novel LC-MS/MS Method.

Therapeutic drug monitoring (TDM) using cyclin-dependent kinase inhibitors (CDK4/6is) is a novel approach for optimizing treatment outcomes. Currently, palbociclib, ribociclib, and abemaciclib are the available CDK4/6is and are primarily coadministered with letrozole. This study aimed to develop and validate an LC-MS/MS method for the simultaneous analysis of CDK4/6is, 2 active metabolites of abemaciclib (M2 and M20), and letrozole in human plasma for use in TDM studies. Sample pretreatment comprised protein precipitation with methanol and dilution of the supernatant with an aqueous mobile phase. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column (2.5 μm, 3.0 × 75 mm XP), with methanol serving as the organic mobile phase and pyrrolidine-pyrrolidinium formate (0.005:0.005 mol/L) buffer (pH 11.3) as the aqueous mobile phase. A triple quadrupole mass spectrometer was used for the detection, with the ESI source switched from negative to positive ionization mode and the acquisition performed in multiple reaction monitoring mode. The complete validation procedure was successfully performed in accordance with the latest regulatory guidelines. The following analytical ranges (ng/mL) were established for the tested compounds: 6-300, palbociclib and letrozole; 120-6000, ribociclib; 40-800, abemaciclib; and 20-400, M2 and M20. All results met the acceptance criteria for linearity, accuracy, precision, selectivity, sensitivity, matrix effects, and carryover. A total of 85 patient samples were analyzed, and all measured concentrations were within the validated ranges. The percent difference for the reanalyzed samples ranged from -11.2% to 7.0%. A simple and robust LC-MS/MS method was successfully validated for the simultaneous quantification of CDK4/6is, M2, M20, and letrozole in human plasma. The assay was found to be suitable for measuring steady-state trough concentrations of the analytes in patient samples.

HPLC and SFC Enantioseparation of (±)-Trans-β-Lactam Ureas on Immobilized Polysaccharide-Based Chiral Stationary Phases—The Introduction of Dimethyl Carbonate as an Organic Modifier in SFC

A series of nine racemic trans-β-lactam ureas were analyzed for enantiomer separation by high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The separations were performed on three immobilized polysaccharide-based chiral analytical columns (CHIRAL ART Amylose-SA, CHIRAL ART Cellulose-SB and CHIRAL ART Cellulose-SC). In HPLC mode, a normal-phase consisting of n-hexane/2-PrOH (90/10, v/v), a polar organic mobile phase consisting of 100% MeOH or 100% EtOH, and a non-standard mobile phase consisting of 100% dimethyl carbonate (DMC) were investigated. In SFC mode, the mobile phases CO2/alcohol (80/20, v/v) and CO2/DMC/alcohol (MeOH or EtOH; 70/24/6, v/v/v or 60/32/8, v/v/v) were investigated. The best achieved enantioseparation of trans-β-lactam ureas was obtained with an Amylose-SA column. We have shown that the green solvent dimethyl carbonate (DMC) can be efficiently used as a mobile phase in HPLC mode as well as in SFC mode along with the addition of polar organic modifiers (MeOH or EtOH).

MARALIXIBAT IN RAT PLASMA AND ITS PHARMACOLOGICAL STUDIES (BIO-ANALYTICAL METHOD DEVELOPMENT AND VALIDATION BY LC-MS)

The bio-analytical method development of Maralixibat using Elobixibat as an internal standard is a convenient, fast, accurate, and consistent new LC-MS technique and was validated. The present work explains the development of the LC-MS/MS bio-analytical method by RP-18(150x4.6 mm, 3.5µ) column and a binary mixture(0.1% formic acid & methanol) of organic mobile phase in the ratio 60:40. By using liquid-liquid extraction process, these drugs are removed from rat plasma. The linearity in the standard curve was observed under the experimental concentration range. 10%-200% (6-12ng/ml) of Maralixibat. The calibration plots were linear with a regression coefficient of R2> 0.999. Precision, Accuracy, Stability results, and Matrix effect were observed within the acceptable limit. The method is more accessible and effective for analyzing the sample in the body fluids. The work represents that Specificity, Suitability, Accuracy, and linearity parameters ideally agree with the USFDA guidelines and are efficiently practiced in rat plasma for pharmacokinetic studies

Evaluation of multi-solvent size exclusion chromatography columns packed with sub-2 μm particles for the characterization of synthetic polymers

With the recent development of small particle stationary-phases and dedicated instrumentation, the combination of size-exclusion chromatography (SEC) with ultra-high performance liquid chromatography (UHPLC) technology has been realized. It opened up a new polymer analysis technique called UHP-SEC. Although high resolution and fast analysis can be achieved, the multi-solvent suitability for a given column was limited to either organic or aqueous eluents. In this work, the capability of novel SEC columns (AdvanceBio SEC columns) packed with 1.9 μm particles for the characterization of synthetic polymers in organic solvents as well as the multi-solvent compatibility for organic and aqueous eluents have been demonstrated. About six times faster separation for both polystyrene (PS) and polyethylene glycol (PEG) with good peak shape and repeatability were achieved in comparison with standard SEC columns at comparable resolution. Especially for PEG, in contrast to other SEC columns, this column could provide close-to-accurate determination of molecular weights with tetrahydrofuran (THF) as mobile phase. Good reproducibility was obtained after switching several times from water to THF and vice versa with RSD% in retention times less than 0.5 %. Different samples such as polyols, isocyanates and additives can also be analyzed for molecular weight and distribution or composition determination. Volume overload, especially with injection volumes higher than 10 µL needs to be considered. This new column offers a powerful choice for oligomer and polymer analysis with both aqueous and organic mobile phase. Ultimately, hyphenating SEC columns to various detectors can enable more information regarding chemical composition, molecular weight, concentration, and structure.

Selectivity comparison of acetonitrile-methanol-water ternary mobile phases on an octadecylsiloxane-bonded silica stationary phase.

The solvation parameter model was used in this study to investigate various intermolecular interactions that influence retention on the standard C18 stationary phase for the solvent system acetonitrile:methanol (ACN:MeOH, 1:1). In comparison to the organic mobile phase modifiers acetonitrile, acetone, methanol, 2-propanol, and tetrahydrofuran, the solvent strength for the ACN:MeOH (1:1) solvent system was evaluated. To facilitate the interpretation of various intermolecular interactions that contribute to retention on a standard C18 stationary phase for the solvent system ACN:MeOH (1:1), system maps were constructed and compared with those of acetone, tetrahydrofuran, acetonitrile, 2-propanol, and methanol. The solvation parameter models were constructed for the ternary solvent system ACN:MeOH (1:1)-water, and in the models constructed, the coefficient of determination values were from 0.998 to 0.999, the Fisher statistic values for the models were from 1687 to 4015, and the standard error of the estimate values ranged from 0.022 to 0.029. The solvent system ACN:MeOH (1:1) has retention properties more similar to methanol than acetonitrile, indicating methanol's influence is more dominant.

Dimethyl Carbonate as a Mobile-Phase Modifier for Normal-Phase and Hydrophilic Interaction Liquid Chromatography

We studied the use of dimethyl carbonate (DMC) as a non-toxic, aprotic modifier for hydrophilic liquid interaction chromatography (HILIC) and as a modifier for normal-phase liquid chromatography (LC). A comparison of ethyl acetate (EA) and DMC as organic mobile-phase modifiers in hexane for normal-phase LC of phthalates was conducted with a silica column and showed that retention factors (k) at the same modifier percentage were about a factor of two greater for DMC. Detection at 215 nm, possible with DMC, allowed for the better detection of the phthalates by a factor of 10, compared with EA detection, best at a 254 nm wavelength. Using a core-shell silica column, HILIC separations of trans-ferulic acid, syringic acid, and vanillic acid were compared between acetonitrile (MeCN) and DMC as the organic portion of the mobile phase, from 80–95%. The analyte retention for DMC, when compared to MeCN, was about 1.5 times greater, with only a moderate increase in back pressure. Plate count and peak asymmetry were somewhat better for the DMC chromatograms, compared to those with MeCN. Seven mono- and di-hydroxybenzoic acid positional isomers could be resolved effectively with DMC. Sorbate and benzoate preservatives in commercial drinks were also determined.

Unique selectivity of tetrahydrofuran-2-propanol-water ternary mobile phases on a superficially porous particle column in reversed-phase liquid chromatography

Three mixed mobile phase organic modifiers, tetrahydrofuran: 2-propanol 1:1 (v/v), tetrahydrofuran: 2-propanol: 1:3 (v/v), and tetrahydrofuran: 2-propanol: 3:1 (v/v) were studied at 20–70% (v/v) total organic solvent compositions. The solvent strength parameters for the three mixed organic modifiers and system properties were compared to those of more established binary solvent systems, acetonitrile-water and methanol-water. To interpret intermolecular interactions responsible for retention for the three mixed mobile phase organic modifiers, system maps were constructed and compared with acetonitrile and methanol. Three mixed organic mobile phase modifiers on one stationary phase chemistry (Kinetex C18) provide different selectivity than the more established acetonitrile and methanol mobile phase modifiers on the same stationary phase (Kinetex C18) as well as different stationary phase chemistries (Kinetex Biphenyl, Kinetex Phenyl-Hexyl, Kinetex F5, Kinetex XB-C18, and Kinetex EVO C18). The solvation parameter models for all three mixed mobile phase systems the coefficient of determination ranged from 0.991 to 0.999, the Fisher statistic from 338 to 1850, and the standard error of the estimate ranged from 0.024 to 0.097.

Bio-Analytical Method Development and Validation of Asciminib and its Application to Pharmacokinetic Studies in Rat Plasma by Using RP-HPLC

The aim of the proposed study was to validate a rapid, uncomplicated, accurate, robust and sensitive bio-analytical method for quantifying asciminib using ivosidenib as an internal standard in rat plasma. This work provides a summary of recent advances in bio-analytical HPLC methodologies employing a Luna phenyl hexyl column (150 × 4.6 mm, 3.5) with an organic mobile phase of potassium dihydrogen phosphate (adjusted to pH 3.0 with orthophosphoric acid) and acetonitrile in the ratio 40:60. With a correlation coefficient of 0.999, the asciminib calibration curve was linear over the range of 100-2000 ng/mL. Using liquid-liquid extraction, the percent of recovered ASB ranged between 97.8 and 99.9%. The plasma stability of the bench-top and auto sampler remained stable for 24 h in the auto sampler. The T1/2 is 5 h and Tmax is 3 h, as calculated from the pharmacokinetic parameters. The application indicates that all parameters of system suitability, specificity, linearity and accuracy are in good agreement with the prescribed limits; consequently, the current method is highly stable, rapid and capable of analyzing plasma samples. This method is ideally adapted for determining asciminib in pure or dose form due to its novel technology.

Dietary supplement mislabelling: case study on selected slimming products by developing a green isocratic HPLC method for their quality control

Nowadays, a huge population consumes Dietary supplements for losing weight. Products are often claimed as botanical blends, yet they aren't necessarily safe. Misleading labels are also very common. Thus, validated analytical methods for a wide range of slimming compounds are highly needed. Herein, we present a simple HPLC/PDA method for the quantitation of seven popular slimming ingredients. Studied compounds were Caffeine, Raspberry Ketone, trans-Resveratrol, p-Synephrine, p-Octopamine, p-Hordenine and 2-phenethylamine. After optimization, separation was carried out on a C18 column and mobile phase was a mixture of Acetonitrile:Water containing 0.1% phosphoric acid (50:50, %v/v). The last compound was eluted at 9.76 min. Separation was efficient showing baseline- separated symmetric peaks, without using any gradient programs, organic mobile phase modifiers or modified stationary phases. Method validation was done following ICH guidelines. Calibration curves were linear over wide concentration ranges and calculated LOD values were in the range 0.02–0.09 µg/mL. Method greenness was assessed using Analytical Eco-scale, GAPI and AGREE metric tools. Further, four random sample products purchased from online supplement stores were assayed. Results proved some mislabeling actions. To support our findings, standard addition was carried out and average % recoveries were 96.67 – 101.44% with standard deviation ≤ 2.83 between measurements.

Application of a Cholesterol-Based Stationary Phase for the Analysis of Brevetoxins.

A high-performance liquid chromatography protocol for the analysis of brevetoxins has been developed using a silica hydride-based cholesterol column. Brevetoxins are neurotoxins produced by harmful algae that have additional potential as drugs for a number of illnesses/diseases. To develop the optimum conditions, a number of different experimental approaches were tested. These include isocratic and gradient elution, different organic mobile phase components, and temperature variations. A separate protocol was developed for the compounds brevenal and brevenol, also produced by the same algae that make brevetoxins. Brevenal is a natural product under investigation as a therapy for chronic respiratory diseases, such as cystic fibrosis or asthma. The goal of this study was to provide a protocol for the analysis of these compounds that could be further developed into a validated method depending on a particular laboratory's capabilities and to highlight some of the unique features of the cholesterol stationary phase.

Implementation of QbD Approach to the Development of Chromatographic Methods for the Determination of Complete Impurity Profile of Substance on the Preclinical and Clinical Step of Drug Discovery Studies.

The purpose of this work was to demonstrate the use of the AQbD with the DOE approach to the methodical step-by-step development of a UHPLC method for the quantitative determination of the impurity profile of new CPL409116 substance (JAK/ROCK inhibitor) on the preclinical and clinical step of drug discovery studies. The critical method parameters (CMPs) have been tested extensively: the kind of stationary phase (8 different columns), pH of the aqueous mobile phase (2.6, 3.2, 4.0, 6.8), and start (20–25%) and stop (85–90%) percentage of organic mobile phase (ACN). The critical method attributes (CMAs) are the resolution between the peaks (≥2.0) and peak symmetry of analytes (≥0.8 and ≤1.8). In the screening step, the effects of different levels of CMPs on the CMAs were evaluated based on a full fractional design 22. The robustness tests were established from the knowledge space of the screening step and performed by application fractional factorial design 2(4−1). Method operable design region (MODR) was generated. The probability of meeting the specifications for the CMAs was calculated by Monte-Carlo simulations. In relation to literature such a complete AQbD approach including screening, optimization, and validation steps for the development of a new method for the quantitative determination of the full profile of nine impurities of an innovative pharmaceutical substance with the structure-based pre-development pointed out the novelty of our work. The final working conditions were as follows: column Zorbax Eclipse Plus C18, aqueous mobile phase 10 mM ± 1 mM aqueous solution of HCOOH, pH 2.6, 20% ± 1% of ACN at the start and 85% ± 1% of ACN at the end of the gradient, and column temperature 30 °C ± 2 °C. The method was validated in compliance with ICH guideline Q2(R1). The optimized method is specified, linear, precise, and robust. LOQ is on the reporting threshold level of 0.05% and LOD at 0.02% for all impurities.

Comparative analysis of trilobal capillary-channeled polymer fiber columns with superficially porous and monolithic phases toward reversed-phase protein separations.

A trilobal capillary-channeled polymer fiber stationary phase is evaluated for its performance for intact protein separations under reversed-phase high-performance liquid chromatography conditions. The separation quality, operational characteristics, and protein dynamic loading capacity on the fiber phases are compared to commercially-available superficially porous and monolithic columns. The trilobal or "y-shaped" polypropylene fiber phase was employed to separate a synthetic mixture of five proteins (having diverse chemistries and molecular weights). The separation quality was evaluated based on the resolution, peak heights/recoveries, peak widths, and peak areas. The present work illustrates the unique ability to operate at higher linear velocities (47.5mm/s) while maintaining lower back pressures (∼4 MPa), faster separation times (<8 min), and faster gradient rates using the fiber columns while yielding comparable chromatographic performance to the commercial columns. The separations employing the commercial stationary phases operate at lower linear velocities (∼3.0 mm/s), higher back pressures (∼9 MPa), require longer separation times (10 min), and require slightly higher compositions of organic mobile phase to effect protein elution. Likewise, based on breakthrough loading analysis of lysozyme and bovine serum albumin, the trilobal, polypropylene C-CP fiber column stationary phases demonstrate 3-9X greater binding capacities on a bed volume basis versus the commercial columns.

Design of an Experimental Study for the Simultaneous Determination of Cefepime, Piperacillin and Tazobactam Using Micellar Organic Solvent-Free HPLC

Application of Sustainable analytical chemistry concepts has become crucial in order to remove the environmentally harmful impacts originating from the routine use of analytical techniques. Here, a new LC method is developed and its parameters are analyzed, depending on a mixed micellar mobile phase. This was primarily aimed at getting rid of the use of organic solvents in conventional routine analyses. Combinations of tazobactam (TZB) with piperacillin (PPC) or cefepime (CFM) are commonly used as effective antimicrobial therapies, especially for resistant strains. Therefore, the three drugs were separated and quantified using an organic solvent-free mobile phase. The mixed micellar mobile phase was comprised of 15 mM Brij-35 with 38 mM SDS, adjusted to pH 3.5. Separation was performed by HPLC on monolithic RP-C18 column Chromolith® Performance RP-18e (100 mm × 4.6 mm) at a rate of 1 mL per minute of flow in conjunction with a measurement wavelength 210 nm. The method was found valid and applicable in accordance of precision, and accuracy within ranges of 5–100 µg mL−1 for PPC and CFM and of 0.625–12.5 µg mL−1 for TZB. The quality-by-design technique was used to analyze the effect of modifying the mixed micellar ratios on separation efficiency and conclude their behavior. Finally, the suggested approach was assessed applying the green analytical procedure index against the greenest published methodology to show superiority.

​Screening for Enrofloxacin and Ciprofloxacin Residues in Chicken Liver by Liquid Chromatography Tandem Mass Spectrometry Accompanied by Optimal Liquid-liquid Extraction with Phosphoric Acid

Background: Enrofloxacin used considerably on large scale among poultry birds. Detection and monitoring of its residues is vital in the domestic and export market. A simple and rapid LCMS/MS method for screening of Enrofloxacin and its metabolite residues in poultry liver samples was described. Methods: Target analytes were extracted with a solvent combination of 5% phosphoric acid in 50% acetonitrile in water. It was followed by deep freezing for efficient separation of the liquid phase. Later extractants were subjected to centrifugation at 4oC, 10,000 rpm for 20 minutes and supernatant was filtered and injected into LCMS/MS. 0.1% formic acid is used as mobile phase additive for both aqueous and organic mobile phase acetonitrile. Result: Accuracy and precision values of the method are within the acceptable limit of ( less than 5% RSD) accorded by the European commission. Standardized method has been applied to determine the Enrofloxacin and Ciprofloxacin residues in liver samples collected in local markets and found within maximum residue limits.

Green bioanalysis: an innovative and eco-friendly approach for analyzing drugs in biological matrices.

Green bioanalytical techniques aim to reduce or eliminate the hazardous waste produced by bioanalytical technologies. A well-organized and practical approach towards bioanalytical method development has an enormous contribution to the green analysis. The selection of the appropriate sample extraction process, organic mobile phase components and separation technique makes the bioanalytical method green. UHPLC-MS is the best option, whereas supercritical fluid chromatography is one of the most effective green bioanalytical procedures. Nevertheless, there remains excellent scope for further research on green bioanalytical methods. This review details the various sample preparation techniques that follow green analytical chemistry principles. Furthermore, it presents green solvents as a replacement for conventional organic solvents and highlights the strategies to convert modern analytical techniques to green methods.

BIOANALYTICAL METHOD FOR SIMULTANEOUS ESTIMATION OF RIBOCICLIB AND LETROZOLE AND ITS APPLICATION TO PHARMACOKINETIC STUDIES USING ULTRA-PERFORMANCE LIQUID CHROMATOGRAPHY

Objective: An easy, quick, precise, active and reproducible UPLC technique was developed for the bioanalytical method of Ribociclib and Letrozole using Lapatinib as the internal standard. Methods: This article summarizes the recent progress on bioanalytical UPLC method using phenyl column (100x2.1 mm, 1.7µ) column and an organic mobile phase of 0.1% Tri fluoro acetic acid and Acetonitrile in 50:50 with a flow of 0.5 ml/min. An injection volume of 5 microliters was used. Lapatinib was used as an internal standard. Results: The drugs were found at Letrozole (m/z 435.46/216.55), Ribociclib (m/z 506.34/167.43) and Lapatinib (internal standard, m/z 582.37/184.29), respectively. Tests were performed in less than five minutes on Ribociclib (r2 = 0.99953; concentration range: 2 to 40 ng/ml) and Letrozole (r2 = 0.99915; concentration range: 0.025 to 0.5 ng/ml). The study's precision and recovery results were determined to be accurate. Accuracy, precision, recovery, matrix effect and stability results were found to be within the suitable limits. Simple and efficient method was developed and utilized in pharmacokinetic studies to see the investigated analyte in body fluids. Conclusion: The application denotes all the parameters of system suitability, specificity, linearity and accuracy are in good agreement with USFDA guidelines and applied effectively for the investigation of pharmacokinetic studies in rabbit.

Towards a miniaturized on-site nano-high performance liquid chromatography electrospray ionization ion mobility spectrometer with online enrichment

Safeguarding water quality is resource-intensive and costly. Especially in cases of accidents or disasters, compact devices that allow quick assessment of the current situation are lacking. The objective of this work is the development of a portable measuring device for on-site detection of pollutants in water based on nano-high performance liquid chromatography (nano-HPLC) and electrospray ionization (ESI) ion mobility spectrometry (IMS). Integrated online enrichment by means of solid phase extraction (SPE) further improves sensitivity. In this work, an SPE cartridge exchange unit is presented, which was developed by additive manufacturing in a cost-effective and resource-efficient way. Prerequisites are an easy adaptation to commercially available SPE cartridges and pressure stability of up to 50 bar. In addition, a compact ESI-IMS with 75 mm drift tube length and a resolving power of R = 100 is presented that enables ionization, separation based on ion mobility and detection of analytes at a flow rate of 0.6 – 1.8 µL/min from the liquid phase. This approach also allows miniaturization of the overall system leading to a reduction in energy requirements and the amount of solvents used. For future environmentally benign systems, complete elimination of toxic solvents would be ideal. Therefore, acetonitrile and the nontoxic ethanol are compared as organic mobile phase in terms of elution and ionization efficiency. For characterization, a test mixture containing relevant target analytes, such as chlortoluron, isoproturon, pyrimethanil, mepanipyrim, cyprodinil and carbamazepine, is analyzed. In addition, the analytical greenness metric approach tool is used to evaluate the overall system in terms of its green credentials. It was shown that ethanol can be well used as an organic solvent for the mobile phase and even exhibits better ionization than acetonitrile for the selected model analytes. Furthermore, a relatively high orthogonality of O=0.53 and an effective 2D peak capacity of 2Dneff=174 are reached. Due to the overall miniaturization and splitless coupling, the aims of green chemistry can be met, and ideally a value of 0.92 can be achieved using the AGREE tool for the presented system.