Development Of Solid-phase Extraction Method Research Articles

B-286 Single Experiment, Single Plate Solid Phase Extraction (SPE) Optimization using 47 Drug Analytes as an Example

Abstract Background SPE of biological matrices isolates analytes of interest from interfering matrix components that can affect LC-MS/MS quantitation. Optimal SPE conditions are dependent upon the sample matrix and analyte properties and typically require multiple experiments to determine optimal conditions for SPE extraction. Here, a 96-well method development plate was utilized to streamline method development for a panel of 47 clinical research drug analytes: 14 antipsychotics, 22 antidepressants and 11 anticonvulsants. Methods An SPE plate with four polymeric sorbents: reversed phase (X), strong and weak cation-exchange and weak anion-exchange mixed-mode phases (X-C, X-CW and X-AW) was used. The 47 drugs analytes were extracted on all four sorbents using three sets of conditions: acidic pretreatment/wash (aq) with basic elution (AB), neutral pretreatment/wash (aq) with neutral elution (NN), and basic pretreatment/wash (aq) with acidic elution (BA). A 50/50 methanol/water wash was also included. Elution used neutral or pH adjusted ethyl acetate/isopropanol or methanol/acetonitrile. A reagent blank, matrix blank, extracted serum samples spiked post-elution (n=2), and spiked serum (n=4) were extracted on each sorbent using each set of conditions. Optimal conditions were determined by calculating absolute percent recovery for each analyte. Results Recovery for antipsychotics was 85-97% using X-CW-AB, except Chlorpromazine (59%). It had better recovery (80%) using X-AB. Recovery for the antidepressants was 75-112% using X-C-AB, except Bupropion (35%) and Selegiline (10%). Bupropion had better recovery (83% and 95%) using X or X-CW and BA. Selegiline had better recovery using X, X-CW and X-AW with BA (83-92%). Anticonvulsants comprise zwitterionic, sulfonamides, neutral, acidic, and basic compounds with widely varying pKa and polarity. Targeting a single method for these analytes is difficult. The best recovery for anticonvulsants used X-CW-AB with several exceptions. Lacosamide, Felbamate, and Levetiracetam are neutral and among the most polar analytes and had 7-31% recovery under all SPE conditions tested. Zwitterionic Gabapentin and Pregabalin had 50-53% recovery from X-CW and X-C sorbents. The stronger protic elution (ammoniated methanol/acetonitrile vs ethyl acetate/isopropanol ) improved solubility for complete elution. Oxcarbazepine had 37% recovery from X-CW-AB, but recovery was 71% under BA conditions. Neutral, polar Zonisamide and Topiramate (Sulfonamide compounds) recovery was 25-26% using X-CW-AB. However, recovery was better (47% and 83%) under NN conditions, suggesting the analytes didn’t undergo complete elution from the X-CW sorbent. A stronger elution solvent would improve recovery from X-CW. Conclusions Most antipsychotics were recovered with X-CW-AB. Most antidepressants could be extracted using X-C-AB. Some analytes had higher recovery using hydrophobic interaction (X) SPE. A single mixed-mode SPE two-step elution protocol using a stronger elution solvent may be feasible. Anticonvulsants had mixed results. Some would require a stronger elution solvent. Some could be included in the other two panels to maximize recovery, but some had low recovery under all conditions tested. The method development plate screened 12 SPE methods for 47 analytes in a single experiment, greatly reducing the time and labor required to identify the best sorbent and starting conditions for SPE extraction optimization for drug analysis. This workflow could be implemented for other SPE method development projects.

Determination of morpholinium ionic liquid cations in environmental water samples: development of solid-phase extraction method and ion chromatography.

An ion chromatography and solid-phase extraction method has been applied for the separation and detection of morpholinium cations in environmental water samples. The water samples were purified and enriched by a UF-SCX sulfonic acid extraction column and eluted with 0.5molL-1 phosphoric acid/sodium dihydrogen phosphate buffer solution/55% methanol. The target compounds were separated on a carboxylic acid cation exchange column with 5.0mmolL-1 methane sulfonic acid/2% acetonitrile as the mobile phase and direct conductivity detection. The method has been successfully applied to extract morpholinium cations from spiked water samples of Songhua River, Hulan River, East Lake, and Mopanshan Reservoir in China with the recoveries ranging from 75.0% to 98.3%. The relative standard deviations of intraday precision and interday precision are 2.1% and 5.9% or less, respectively. Using this method it is possible to preconcentrate water samples to 0.01-0.04mgL-1. The results show that the method is applicable to detection of morpholinium ionic liquid cations in environmental water samples and provides a new approach for monitoring ionic liquids in environmental water. Graphical abstract The analysis procedure of morpholinium ionic liquids in environmental water samples.

Matrix influence on determination of organochlorine pesticide residues in water by solid phase extraction coupled to gas chromatography-mass spectrometry

The presence of a sample matrix is one of the most important practical considerations in gas chromatography analysis as there are potentially numerous problems associated with matrix based injections. This paper aims to highlight the distinction between blank sample analysis and real sample analysis using automated solid phase extraction (SPE) and gas chromatography-mass spectrometry. Four reversed sorbent phases, including a Supelco LC-18, Strata C-18-E and Strata-X (styrene divinyl benzene) were used for SPE method development using an automated Gilson GX-271 Aspec TM liquid handling instrument to determine the best solid phase and treatment for optimum organochlorine determination. The method developed proved to be valid when tested against parameters such as calibration range, coeffi cient of regression, linearity, repeatability and sensitivity. The StrataX and LC-18 cartridges produced the best recoveries, varying between 90% and 130% for most analytes. The LC-18 was selected for further analysis of the matrix effects as it showed greater reproducibility and method parameter robustness. Various real matrix sample volumes were tested on the selected LC-18 cartridge to determine its optimum maximum matrix load for effi cient recoveries (breakthrough volume equivalent). A 100 ml sample volume was determined as the optimum matrix load volume as it produced more precise recoveries than other spiked sample matrix volumes. Visual comparison and analysis of selective ion monitoring chromatograms of both matrix based and matrix-free extracts indicate that there are signifi cant matrix effects potentially capable of adversely affecting the chromatographic system from producing accurate identifi cation and quantifi cation of target analytes.

Past, Present, and Future of Solid Phase Extraction: A Review

Sample preparation of target compounds from biological, pharmaceutical, environmental, and food matrices is one of the most time-consuming steps in analytical procedures. Extraction techniques are dominant, especially those based on the processes running on the phase such as liquid-liquid and/or liquid-solid. Due to the reproducibility of data, precision, relatively low cost of the appropriate analysis, simplicity of the determination, and the possibility of direct combination of those techniques with other methods (both on-line and off-line), they have become the most widespread in routine determinations. Additionally, sample pretreatment procedures have to be more selective, cheap, quick, and environmentally friendly. Selectivity is obtained by using procedures based on immunoaffinity or molecular imprinting. Reduction of costs can be obtained by automation of the extraction procedures (automated SPE) or techniques like column-switching. Reducing at least the time for sample preparation is achieved by introducing miniaturization techniques (multi-well SPE). This review summarizes the current achievements and application of solid phase extraction (SPE). The main aim is to deal with the utilization of different types of sorbents for solid-phase extraction and emphasize the use of new synthesized sorbents as well as to bring together studies on a systematic approach to SPE method development.

Development of solid-phase extraction method for the determination of aromatic sensitisers in paper mill effluent

In this paper, a procedure for the determination of 11 aromatic hydrocarbon-type sensitisers and their related compounds from water samples, used in the manufacture of thermal paper, is presented. The compounds were extracted using a solid-phase extraction (SPE) cartridge with an octadecyl (C18) or a phenyl-bonded silica (PH) sorbent and then determined by gas chromatography–mass spectrometry (GC–MS). Factors affecting the performance of the extraction steps were thoroughly evaluated, and their effects on the yield of the sample preparation were discussed. Under optimised experimental conditions, SPE cartridges were conditioned with 10 mL hexane followed subsequently by 10 mL methanol, loaded with water sample at 2 mL min−1, and eluted with 10 mL hexane at 1.5 mL min−1. The limits of detection and quantification, calculated for signal-to-noise ratios of 3 and 10, were in the range of 1–5 µg L–1 and 2.5–10 µg L–1, respectively. Recovery yields of the present method using river water were in the range of 88%–112% with a C18 sorbent and 86%–116% with a PH sorbent. The repeatability, expressed as a relative standard deviation, was in the range of 2.8%–11% with a C18 sorbent and 0.7%–9.7% with a PH sorbent (n = 4). Analysis of paper mill effluents revealed the presence of aromatic hydrocarbon-type sensitisers with maximum concentrations of up to 5.2 µg L−1.

Sample preparation development and matrix effects evaluation for multianalyte determination in urine

The development of a generic analytical method remains difficult when a high number of compounds has to be simultaneously considered. This study proposes an innovative strategy for the development of a solid phase extraction (SPE) procedure before liquid chromatography-mass spectrometry analysis of 34 diuretics and beta-blockers in urine samples. These compounds have been selected since they are often encountered in anti-doping control. The principle is based on the selection of representative analytes during SPE protocol optimization, allowing a drastic reduction of generated data and development time. To select the representative compounds, all substances were classified based on their SPE behavior with a generic method and groups were formed with the help of a chemometric tool, namely hierarchical cluster analysis (HCA). One representative analyte per group was selected and used for subsequent SPE method development. Once the SPE method was developed, compounds were analyzed by LC-MS and matrix effects were evaluated to determine the influence of the matrix on the SPE process and MS signal alteration due to endogenous compounds. As a result, matrix effects evaluation must be performed on all analytes; representative compounds previously selected for SPE development were unable to predict matrix effects.

New practical algorithm for modelling analyte recovery in bioanalytical reversed phase and mixed-mode solid phase extraction

Solid phase extraction (SPE) is a widely used method for sample cleanup and sample concentration in bioanalytical sample preparation. A few methods to model the retention behaviour on SPE cartridges have been described previously but they are either not applicable to ionised species or are not suitable when using multiple wash and elution steps with solvents differing in volume, modifier concentration and acidity. Furthermore, these models were not applied to mixed mode SPE sorbents. In order to overcome these limitations a new SPE modelling algorithm was proposed. The retention behaviour was determined directly on the SPE cartridge by connecting the cartridge online with an HPLC system using a simple but suitable device that was developed and described. The results from these online experiments were used to model the elution behaviour using a quadratic retention function combined with an exponentially modified Gaussian peak shape model to predict analyte recovery under different wash and elution conditions. The validity of the proposed algorithm was tested using practical SPE experiments with an aqueous test mixture as well as with spiked human plasma. Different sequential wash and elution steps were performed using solvents differing in volume and composition. The predicted band shape and recoveries in each collected step were in good agreement with the results obtained from practical experiments. The proposed algorithm is very useful for the description of the SPE behaviour of the analytes on the actual used SPE cartridge and can be used in structural and automated SPE method development.

Application of cation-exchange solid-phase extraction for the analysis of amino alcohols from water and human plasma for verification of Chemical Weapons Convention

The analysis of nitrogen containing amino alcohols, which are the precursors and degradation products of nitrogen mustards and nerve agent VX, constitutes an important aspect for verifying the compliance to the CWC (Chemical Weapons Convention). This work devotes on the development of solid-phase extraction method using silica- and polymer-based SCX (strong cation-exchange) and MCX (mixed-mode strong cation-exchange) cartridges for N, N-dialkylaminoethane-2-ols and alkyl N, N-diethanolamines, from water. The extracted analytes were analyzed by GC–MS (gas chromatography–mass spectrometry) in the full scan and selected ion monitoring modes. The extraction efficiencies of SCX and MCX cartridges were compared, and results revealed that SCX performed better. Extraction parameters, such as loading capacity, extraction solvent, its volume, and washing solvent were optimized. Best recoveries were obtained using 2 mL methanol containing 10% NH 4OH and limits of detection could be achieved up to 5 × 10 −3 μg mL −1 in the selected ion monitoring mode and 0.01 μg mL −1 in full scan mode. The method was successfully employed for the detection and identification of amino alcohol present in water sample sent by Organization for Prohibition of Chemical Weapons (OPCW) in the official proficiency tests. The method was also applied to extract the analytes from human plasma. The SCX cartridge showed good recoveries of amino alcohols from human plasma after protein precipitation.

Cetyltrimethylammonium Bromide-Coated Magnetic Nanoparticles for the Preconcentration of Phenolic Compounds from Environmental Water Samples

The research presented in this paper investigates the adsorption of cation surfactants--cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC)--onto magnetic nanoparticles and the application of this mixed hemimicelles solid-phase extraction (SPE) method for the preconcentration of several typical phenolic compounds-bisphenol A (BPA), 4-tertoctylphenol (4-OP), and 4-n-nonylphenol (4-NP)--from environmental water samples. In this novel SPE method, the charged surfactants CTAB and CPC form mixed hemimicelles on Fe3O4 nanoparticles (Fe3O4 NPs), which causes retention of analytes by strong hydrophobic and electrostatic interactions. The SPE method combines the advantages of mixed hemimicelles and magnetic nanoparticles. In order to provide guidelines forthe mixed hemimicelles SPE method development, surfactant adsorption isotherms and zeta-potential isotherms were also investigated. The main factors affecting the adsolubilization of analytes, such as the amount of Fe3O4 NPs and surfactants, the type of surfactants, the solution pH,the sample loading volume, and the desorption conditions, were investigated and optimized. A concentration factor of 800 was achieved by the extraction of 800 mL of several environmental water samples using this SPE method. Under the selected conditions, detection limits obtained for BPA, 4-OP, and 4-NP were 12, 29, 34 ng/L, respectively. The accuracy of the method was evaluated by recovery measurements on spiked samples, and good recoveries (68-104%) with low relative standard deviations from 2 to 7% were achieved. The advantages of this new SPE method include high extraction yields, high breakthrough volumes, short analysis times, and easy preparation of sorbents. To the best of our knowledge, this is the first time that a mixed hemimicelles SPE method based on magnetic separation and nanoparticles has been used for the pretreatment of environmental water samples.

Extraction of acidic degradation products of organophosphorus chemical warfare agents: Comparison between silica and mixed-mode strong anion-exchange cartridges

The analysis of alkyl alkylphosphonic acids (AAPAs) and alkylphosphonic acids (APAs), the hydrolyzed products of nerve agents, constitutes an important aspect for verifying the compliance to the Chemical weapons convention (CWC). This work devotes on the development of solid-phase extraction method using polymeric mixed-mode strong anion-exchange (Oasis MAX) cartridges for extraction of AAPAs and APAs from water. The extracted analytes were analyzed by GC–MS under full scan and selected ion monitoring mode. The extraction efficiencies of MAX and silica-based anion-exchange cartridges were compared, and results revealed that MAX sorbents yielded better recoveries. Extraction parameters, such as loading capacity, extraction solvent, its volume, and washing solvent were optimized. Best recoveries were obtained using 1 mL of acidic methanol (0.1 M), and limits of detection could be achieved up to 5 × 10 −4 μg mL −1 (in SIM) and 0.05 μg mL −1 in full scan mode. The method was successfully employed for the detection and identification of alkylphosphonic acids present in soil sample sent by the Organization for Prohibition of Chemical Weapons (OPCW) in the official proficiency tests.

Development of solid-phase extraction method and its application for determination of hydrochlorothiazide in human plasma using HPLC.

A high-performance liquid chromatographic method was developed, validated and applied for the determination of hydrochlorothiazide in human plasma. The effects of mobile phase composition, buffer concentration, mobile phase pH and concentration of organic modifiers on retention of hydrochlorothiazide and internal standard were investigated. The method involves solid-phase extraction on RP-select B cartridges followed by isocratic reversed-phase chromatography on a Hibar Lichrospher 100 RP-8 column with UV detection at 230 nm. The recovery, selectivity, linearity, precision and accuracy of the method were evaluated from spiked human plasma samples. Limit of quantification was 10 ng mL(-1). The method has been implemented to monitor hydrochlorothiazide levels in patient samples.

ChemInform Abstract: Solid-Phase Extraction for Combinatorial Libraries

Solid-phase extraction (SPE) has during the last three years emerged as a convenient method for the purification of compound libraries prepared by solution synthesis. The widespread use of SPE in combinatorial chemistry can be explained by straightforward SPE method development facilitated by the availability of numerous commercial SPE resins. High-speed automated SPE is readily accomplished by taking advantage of commercial laboratory robot systems. The present review summarizes and discusses advancements made in the use of different SPE resins and molecule tagging techniques for optimization of ion-exchange, reversed-phase, normal-phase and fluorous-phase SPE in combinatorial chemistry.

Solid-phase extraction for combinatorial libraries

Solid-phase extraction (SPE) has during the last three years emerged as a convenient method for the purification of compound libraries prepared by solution synthesis. The widespread use of SPE in combinatorial chemistry can be explained by straightforward SPE method development facilitated by the availability of numerous commercial SPE resins. High-speed automated SPE is readily accomplished by taking advantage of commercial laboratory robot systems. The present review summarizes and discusses advancements made in the use of different SPE resins and molecule tagging techniques for optimization of ion-exchange, reversed-phase, normal-phase and fluorous-phase SPE in combinatorial chemistry.