Polystyrene-divinylbenzene Resin Research Articles

Synthesis of Hyper-cross-linked Nonpolar Polystyrene Divinylbenzene Resins by Pendent Vinyl Groups and Application to the Decolorization of Cane Molasses.

Cane molasses is a by-product of sugar industry. It is widely used in fermentation field, but pigment compounds affect its further application. In this study, nonpolar hyper-cross-linked adsorption resins (HCARs) were synthesized by pendent vinyl groups cross-linking reaction, and were applied to decolorization of molasses. The correlation between the structure and the decolorization performance of HCARs was studied, and the results showed that the Brunauer-Emmett-Teller (BET) surface area and the pore volume of the resin significantly increased to 574.4 m2·g-1 and 1.40 cm3·g-1 after the Friedel-Crafts alkylation reaction with a catalyst dosage of 2.25% at 343K for 7h. Furthermore, the decolorization rate of molasses by the HCAR was 74%, and recycle decolorization performance of the resin was stable. The adsorption kinetics results showed that the pseudo-second-order dynamic model could more realistically reflect the decolorization mechanism of molasses on HCARs, and liquid film diffusion is the main rate-limiting step. The results of fixed-bed experiments show that D-ST-DVB resin has a good decolorization effect and recycling ability. Therefore, it is a feasible strategy for the decolorization of molasses with nonpolar HCAR.

Versatile in silico modeling of XAD-air partition coefficients for POPs based on abraham descriptor and temperature

The concentration of persistent organic pollutants (POPs) makes remarkable difference to environmental fate. In the field of passive sampling, the partition coefficients between polystyrene-divinylbenzene resin (XAD) and air (i.e., KXAD-A) are indispensable to obtain POPs concentration, and the KXAD-A is generally thought to be governed by temperature and molecular structure of POPs. However, experimental determination of KXAD-A is unrealistic for countless and novel chemicals. Herein, the Abraham solute descriptors of poly parameter linear free energy relationship (pp-LFER) and temperature were utilized to develop models, namely pp-LFER-T, for predicting KXAD-A values. Two linear (MLR and LASSO) and four nonlinear (ANN, SVM, kNN and RF) machine learning algorithms were employed to develop models based on a data set of 307 sample points. For the aforementioned six models, R2adj and Q2ext were both beyond 0.90, indicating distinguished goodness-of-fit and robust generalization ability. By comparing the established models, the best model was observed as the RF model with R2adj = 0.991, Q2ext = 0.935, RMSEtra = 0.271 and RMSEext = 0.868. The mechanism interpretation revealed that the temperature, size of molecules and dipole-type interactions were the predominant factors affecting KXAD-A values. Concurrently, the developed models with the broad applicability domain provide available tools to fill the experimental data gap for untested chemicals. In addition, the developed models were helpful to preliminarily evaluate the environmental ecological risk and understand the adsorption behavior of POPs between XAD membrane and air.

A chemically functionalized hydroxyacetamide anchored polymeric adsorbent for the selective separation of zirconium from acidic aqueous solutions

In the present study, a chelating hydroxyacetamide anchored resin (PS-HOAc), prepared by the chemical modification of a commercially available chloromethylated polystyrene-divinylbenzene (PS-DVB) resin, was developed for the removal of Zr(IV) from acidic aqueous solutions. FT-IR, thermogravimetry, and SEM-EDX studies revealed the chemical linking of hydroxyacetamide group on the polystyrene network. The synthesized PS-HOAc resin has manifested to be highly selective for the adsorption of Zr(IV) as compared to Nd(III) and U(VI) in 0.1 M to 4 M nitric acid feed solutions. The adsorption behavior of Pu(IV) was comparable with Zr(IV). The apparent adsorption capacity for the adsorption of Zr(IV) derived by the Langmuir adsorption isotherm model was 92.6 mg.g−1, which is comparable with the equilibrium adsorption capacity derived from the Pseudo-first-order (Lagergren) model (93.6 mg.g−1). Selective separation of Zr(IV) in the presence of U(VI) and Nd(III) was also established by column studies experiments.

Ion exchange removal and resin regeneration to treat per- and polyfluoroalkyl ether acids and other emerging PFAS in drinking water

Ion exchange (IX) is a promising technology to remove legacy anionic per- and polyfluoroalkyl substances (PFAS) from water. As increasing numbers of per- and polyfluoroalkyl ether acids (PFEA) and other emerging PFAS were detected in the environment, it is necessary to understand how well IX resins remove these emerging PFAS for drinking water treatment. In this study, nine commercially available IX resins were tested to treat a drinking water source spiked with 40 legacy and emerging PFAS at 600 ng/L, including PFEA, perfluoroalkyl carboxylic and sulfonic acids, fluorotelomer sulfonic acids, perfluoroalkane sulfonamides, perfluoroalkane sulfonamidoacetic acids, and zwitterionic species. With limited contact time (15 min), PFAS properties such as the fluorinated chain length, charge, and functional groups all affected PFAS adsorption to resins. However, the impact of PFAS properties on PFAS removal became less pronounced when the contact time increased beyond 2 h, while the resin polymer matrix became the critical factor for PFAS removal. All five tested polystyrene-divinylbenzene (PS-DVB) resins achieved more than 90% removal in 24 h of 35 PFAS compounds, while polymethacrylate and polyacrylic resins achieved >90% removal for less than half of the compounds. Regenerating PS-DVB resin was investigated using different salt species, regenerant pH, brine concentrations, and methanol contents. Sodium chloride and ammonium chloride were found the best brines for regenerating the tested resins. Increasing brine concentrations enhanced the regeneration efficiency, especially for short-chain PFAS. Using simple salt regenerants, up to 94% of selected short-chain PFAS was released from resins designed for general water treatment, but no meaningful regeneration was achieved for long-chain PFAS or PFAS-specific resins when the organic solvent content was less than 20%.

Simulated-moving-bed technology for purification of the prebiotics galacto-oligosaccharides

A commercial galacto-oligosaccharide (GOS) syrup with prebiotic properties was purified with simulated moving bed (SMB) chromatography to separate undesired side products induced by synthesis reaction mechanism. A promising polystyrene-divinylbenzene resin stationary phase has been characterized with regard to its selective adsorption behavior. The chosen chromatographic system allows a pseudo binary separation of the multi-component GOS syrup mixture exploiting a multi-column continuous chromatographic process. Suitable SMB operation parameters were estimated by means of the equilibrium (triangle) theory, further optimized by modelling the separation in more detail and finally validated experimentally. Changes of temperature, concentration of the feed as well as in the instrumental configuration (open loop, closed loop and 3 zones) were examined with a classical SMB plant in lab scale size. Highly purified GOS products could be obtained with purities up to >99% in the extract and raffinate fractions. A quantitative description of the transfer from batch chromatography to the continuous separation process via SMB technology is provided, indicated significant potential for a scale-up.

Removal of fermentation inhibitors from pre-hydrolysis liquor using polystyrene divinylbenzene resin

BackgroundThe presence of soluble lignin, furfural and hydroxymethylfurfural (HMF) in industrial pre-hydrolysis liquor (PHL) from the pulping process can inhibit its bioconversion into bioethanol and other biochemicals. Although various technologies have been developed to remove these inhibitors, certain amounts of sugars are also inevitably removed during the treatment process. Hence, polystyrene divinylbenzene (PS-DVB) resin was used as an adsorptive material to simultaneously remove fermentation inhibitors while retaining sugars with high yields to improve the fermentability of PHL after acid hydrolysis by enriching its xylose concentration. The fermentability of acid-hydrolyzed PHL (A-PHL) was evaluated by the bioconversion into ethanol and xylosic acid (XA) after treatment with PS-DVB resin.ResultsThe results showed that the highest xylose concentration (101.1 g/L) in PHL could be obtained by acid hydrolysis at 100 °C for 80 min with 4% acid, while the concentration of fermentation inhibitors (furfural, HMF and lignin) in PHL could also be significantly improved during the acid-hydrolysis process. After treatment with PS-DVB resin, not only were 97% of lignin, 92% of furfural, and 97% of HMF removed from A-PHL, but also 96% of xylose was retained for subsequent fermentation. With resin treatment, the fermentability of A-PHL could be improved by 162–282% for ethanol production from A-PHL containing 30–50 g/L xylose and by 18–828% for XA production from A-PHL containing 90–150 g/L xylose.ConclusionsThese results confirmed that PS-DVB resin can remove inhibitors from PHL before producing value-added products by bioconversion. In addition, this work will ideally provide a concept for producing value-added chemicals from pre-hydrolysis liquor, which is regarded as the waste stream in the pulping process.

Application of response surface methodology for optimization of oxytetracycline hydrochloride degradation using hydrogen peroxide/polystyrene-supported iron phthalocyanine oxidation process.

Inspired by metalloporphyrin-based enzymes, a biomimetic catalyst, R-N-Fe, was prepared by grafting iron phthalocyanine (FePc) covalently onto a macroporous chloromethylated polystyrene-divinylbenzene resin (R), which was pre-functionalized using 4-aminopyridine (4-ampy) as an axial ligand. The novel catalyst was used for the degradation of oxytetracycline hydrochloride (OTCH). The response surface methodology was employed to optimize the independent operating parameters, including temperature, catalyst amount, H2O2 dosage, and initial pH value. The results displayed that the initial pH and temperature had the most significant effect on the removal efficiency. Under optimum conditions, the OTCH removal efficiency was 93.98%. Additionally, the classical quenching experiment and electron paramagnetic resonance (EPR) test indicated that R-N-Fe could generate hydroxyl radicals by decomposing H2O2, which was the main active species for eliminating OTCH. Furthermore, R-N-Fe can be easily recycled and can maintain high stability in the reusability test, rendering it a good potential for practical application.

Maximizing the zinc ions removal by organic ligand-stabilized conjugate polysterene macronet material

Non-ionogenic cross-linked polystyrene-divinylbenzene resin (PAD-600) is modified with two different organic ligands: 2-amino-1-methylbenzimidazole (MAB) and diethyldithiophosphoric acid (DEDTP). The PAD600-MAB and PAD600-DEDTP have a porous microstructure, and the impregnated MAB and DEDTP molecules are homogenously distributed on the surface of PAD-600 via the hydrophobic part of organic ligands and van der Waals interactions. The sorption capacity and kinetics for Zn2+ removal are studied by a batch method. The Zn2+ sorption followed the Freundlich model (Kf = 1.11 for PAD600, Kf = 2.09 for PAD600-DEDTP, and Kf = 1.45 for PAD600-MAB) and pseudo-second order (k2 = 33.13 g∙mmol∙min–1 for PAD600, k2 = 0.35 g∙mmol∙min–1 for PAD600-DEDTP, and k2 = 3.45 g∙mmol∙min–1 for PAD600-MAB). The interaction of MAB and DEDTP with Zn2+ on the surface of PAD-600 can maximize the sorption of Zn2+ and change the morphology from homogenous porous to heterogeneous low-porous state. The FTIR spectra reveal the impregnation efficiency and the formation of zinc complexes after Zn2+ sorption. The equilibrium and maximum sorption are reached after 1 h at pH = 6. The effects of pH and temperature on Zn2+ sorption are also explored. PAD600-MAB exhibits a lower sorption capacity at higher temperature than PAD600-DEDTP due to the formation of stable zinc dialkyldithiophosphate on the surface. The computer modeling confirms the contribution of electrostatic and van der Waals forces to the solid stability for adsorption process, and the direct interactions of organic ligands with Zn2+ are highly dependent on complex formation. As inexpensive and green sorbents, the PAD600-MAB and PAD600-DiPDTP can be used for selective concentration and separation of various metal ions.

A sustainable process for procuring biologically active fractions of high-purity xylooligosaccharides and water-soluble lignin from Moso bamboo prehydrolyzate

BackgroundPrehydrolyzate, which is from the prehydrolysis process in dissolving pulps industry, contains various sugar-derived and lignin compounds such as xylooligosaccharides (XOS), gluco-oligosaccharides, xylose, glucose, and soluble lignin (S-L). The XOS has several beneficial effects on human physiology. XOS and S-L in prehydrolyzate are difficult to efficiently fractionate due to their similar molecular weights and water solubility. In this work, we proposed a sustainable and green process using polystyrene divinylbenzene (PS-DVB) resin to simultaneously separate and recover XOS and S-L. Enzymatic hydrolysis with endo-1,4-β-xylanase and fermentation with P. stipites were sequentially applied to purify XOS to minimize xylose content as well as amplify contents of xylobiose and xylotriose. In addition, 2D-HSQC NMR was used to analyze the structural characteristics of XOS and S-L. Furthermore, the biological abilities of antioxidants and prebiotics of these fractions were investigated by scavenging radicals and cultivating intestinally beneficial bacterias, respectively.ResultsResults showed that PS-DVB resin could simultaneously separate XOS and solubilized lignin with excellent yields of 93.2% and 85.3%, respectively. The obtained XOS after being purified by enzymatic hydrolysis and fermentation contained 57.7% of xylobiose and xylotriose. 10.4% amount of inherent xylan was found in the S-L fraction obtained by PS-DVB resin separation. 2D-HSQC NMR revealed that lignin carbohydrate complexes existed in both XOS and S-L as covalent linkages between lignin and 4-O-methylglucuronoarabinoxylan. The biological application results showed that the antioxidant capacity of S-L was stronger than XOS, while XOS was superior in promoting growth of intestinal Bifidobacteria adolescentis and stimulating production of short-chain fatty acids by Lactobacillus acidophilus.ConclusionsThe proposed strategy of sequentially combining hydrophobic resin separation, enzymatic hydrolysis, and fermentation was successfully demonstrated and resulted in simultaneous production of high-quality XOS and solubilized lignin. These biomass-derived products in prehydrolyzate can be regarded as value-adding prebiotics and antioxidants.

Thermodynamic analysis of polyphenols retention in polymer resin chromatography by van’t Hoff plot and isothermal titration calorimetry

Temperature effect on the adsorption enthalpy of polyphenols was analyzed with van’t Hoff plots using the distribution coefficient, K, determined with isocratic and gradient elution chromatography. Catechin and epigallocatechin gallate (EGCG) were used as model polyphenols. The stationary phase was polystyrene-divinylbenzene (PS-DVB) resin particles and the mobile phase was an ethanol-water mixture. The values of adsorption enthalpy determined by chromatography and isothermal titration calorimetry were obtained in the temperature range of 283 and 318 K. The results obtained by van’t Hoff plots were consistent with the ones obtained with the isothermal titration calorimetry (ITC). The interaction between PS-DVB particles and the polyphenols was found to be exothermic with negative values of enthalpy, –30.1 and –37.7 kJ/mol for catechin and EGCG, respectively.

Selectivity enhanced cation exchange chromatography for simultaneous determination of peptide variants

If strong cation exchange chromatography (SCX) is combined with ion-pair chromatography, then the solute could be retained selectively with the power of mixed separation modes. This combination is termed selectivity enhanced strong cation exchange chromatography (SE-SCX). Macroporous polystyrene-divinylbenzene (PS/DVB) resin with sulfonate coating that conveys ion exchange and reversed phase characteristics was employed. Sodium dodecyl sulfate (SDS) was utilized as a selectivity modifier and an ion-pair reagent. This separation strategy is exploited for a challenging simultaneous separation of peptide variants having similar isoelectric points (pIs) and comparable retention behaviour. Insulin variants were used as a model in this study. The selective separation of insulin and five structurally-related analogues namely; ASPART, LISPRO, GLULISIN, GLARGIN, and DETEMIR was conducted using gradient elution mode. Three eluents were used for the separation of the target compounds. Eluent A was a mixture of acetonitrile and 10 mmol L-1 SDSat ratio (1:1) and was kept at 20% through the run. Eluent B was 20 mmol L-1 KH2PO4 adjusted at pH = 4.0 and eluent C was eluent B plus 1 mol L-1 NaCl that was increased linearly till 80% at 20 min. It was found that the retention of the tested variants can be modeled mainly by electrostatic interaction that might be hydrophobically-assisted. The developed method was validated in accordance with ICH guidelines and was appropriate for the intended purposes. Finally, this study introduces SE-SCX as a new selective separation strategy for peptides and proteins that may open the door for novel mixed mode perspectives in protein analysis.

Selective recovery of indium from scrap LCD panels using macroporous resins

Abstract This papers details a simple, sustainable approach for the recovery and concentrating of indium from waste scrap LCD panels. After manual dismantling, the glass fraction of the panel was pulverized through a mechanical treatment, Indium from crushed glass was then mobilized in an acidic solution such as HCl:HNO3 lixiviant followed by an ultrasonic wave. Indium was successfully adsorbed by three macro porous polystyrene-divinylbenzene resins (Lewatit TP 208, Lewatit TP 260 and Amberlite IRA 743) and the influence of pH, weight of resin, contact time, temperature and type of resin on the efficiency of sorption process were investigated and the optimum condition was found. Theoretical calculations, indicated the In(III) phase formed through the leaching process was InCl3(aq). The adsorbed In(III) onto the resins was effectively desorbed in acidic medium to prepare concentrated indium solution. For the kinetic study, the adsorption onto Lewatit TP 208, Lewatit TP 260 and Amberlite IRA 743 could be fitted to pseudo second-order.

Phosphoramidate‐functionalized Merrifield resin: synthesis and application in actinide separation

AbstractA novel phosphoramidate‐functionalized polymeric resin was synthesized by anchoring diethyl (3‐(1H‐imidazol‐1‐yl)propyl)phosphoramidate group with chloromethylated polystyrene divinylbenzene resin. The grafted resin was characterized using elemental analysis, Fourier transform infrared, solid‐state 31P NMR energy‐dispersive X‐ray spectroscopies, and thermogravimetric analysis. The surface morphology of the functionalized resin was investigated using scanning electron microscopy and the surface area was measured with Brunauer–Emmett–Teller analysis. Sorption affinities of the functionalized resin towards actinides such as Th(IV) and U(VI) were determined under various concentrations of nitric acid solution (0.01–6 mol L−1). Desorption of the actinides from the loaded resin was performed using a solution of 0.01 mol L−1 nitric acid. Reusability of the grafted resin was studied over various successive cycles and the stability of the functional groups on the synthesized resin was monitored using various analytical techniques. © 2017 Society of Chemical Industry

A simple method for calculating the productivity of polyphenol separations by polymer-based chromatography.

A simple method for calculating the productivity of chromatography processes was proposed based on the iso-resolution curve concept. The model separation system was polyphenol separations by polystyrene divinylbenzene resins with the ethanol-water mixture mobile phase. The distribution coefficient K was determined as a function of ethanol concentration I by linear gradient elution experiments. The HETP-mobile phase velocity u curves were determined as a function of I. Using K and HETP, the iso-resolution curve was calculated, from which the productivity was determined as a function of I. It was found that there is an optimum I, where the highest productivity with the minimum amount of mobile phase consumption is obtained.

Preparation of Multi-target Fusarium Toxins (Zearalenone, Deoxynivalenol, T-2, and HT-2 Toxins) Immunoaffinity Column Using Polystyrene-Divinylbenzene as Matrix

The aim of this study was to establish a purifying immunoaffinity column (IAC) for four kinds of Fusarium toxins (ZEN, DON, T-2, and HT-2 toxins) simultaneously, by using polystyrene-divinylbenzene (PS-DVB) as a column matrix. Four different types of PS-DVB resins were selected to prepare the IACs. Among them, two types of resins, GALAK and Agela, were chosen for IAC preparation. The coupling ratios of the monoclonal antibodies and GALAK or Agela resins were 98.37 and 97.64%, the recoveries of the four Fusarium toxins on the GALAK or Agela IACs were 73.02∼91.97 or 66.16∼112.80%, and the RSDs of recoveries were 2.17∼16.53 or 3.42∼12.25%. They can be applied for the purification of Fusarium toxins from the actual food samples. The GALAK resin was a type of matrix with hydrophilic treatment. The recoveries of four Fusarium toxins on Agela IAC were either too low or too high. The adsorption capacities of the GALAK IAC for the four Fusarium toxins were better than those of the Agela IAC. Hence, the research developed a new method for the preparation of multi-target IAC using PS-DVB resin as matrix of column for determination of Fusarium toxins in food. Then, the GALAK IAC was used for flour samples to detect the feasibility of the application in the actual sample.

High Adsorption of Sulfamethoxazole by an Amine-Modified Polystyrene-Divinylbenzene Resin and Its Mechanistic Insight.

Sulfamethoxazole (SMZ) adsorption by a series of amine-modified polystyrene-divinylbenzene resins (PSA/B/C/D) was investigated. All resins showed a similar pH dependent adsorption of SMZ but their capacities were linearly related with the contents of primary amines (-NH2) rather than secondary amines (-NH-). Mechanisms of SMZ adsorption by PSA (highest -NH2 content) were discussed as an example. Due to comparable pKa, H-bonding interactions of -NH2(0) with SMZ(0) (regular H-bond) and SMZ(-) (negative charge-assisted H-bond, (-)CAHB) successively contributed most adsorption (pH 4-9). At weakly acidic pH, -NH2(0) was partially protonated and electrostatic attraction between -NH3(+) and SMZ(-) occurred concurrently, but could be hindered by increased loading of SMZ(0). Hydrophobic/ π-π interactions were not major mechanisms as phenanthrene and nitrobenzenes had little effect on SMZ adsorption. At alkaline pH, where SMZ(-) and -NH2(0) prevailed, adsorption was accompanied by the stoichiometric (∼1.0) proton exchange with water, leading to OH(-) release and the formation of (-)CAHB [SO2N(-)···H···NH2]. The interaction and SMZ spatial distribution in the resin-phase were further confirmed by FTIR and Raman spectra. SMZ was uniformly adsorbed on external and interior surfaces. SMZ adsorption by PSA had low-interference from other coexistent matter, but high stability after multiple regenerations. The findings will guide new adsorbent designs for selectively removing target organics.

Inhibition of the Corrosion of Aluminum Alloy by a Composition of Ion-Exchange Pigments

It is shown that natural zeolites of the clinoptilolite-type modified with zinc cations serve as efficient corrosion inhibitor for aluminum alloys in the media of weakly acid atmospheric precipitations. The combination of Zn-zeolite with polystyrene-divinylbenzene resin modified with phosphate anions improves its protective properties due to the formation of corrosion-resistant films on the surfaces of alloys. Zinc-modified zeolite and its composition with phosphate-containing anion-exchange resins represent promising inhibiting pigments for paint-and-lacquer coatings on aluminum alloys.

Determination of methylene bridge crosslinking in chloromethylated PS-DVB resins

We present the development of a method for the determination of methylene bridge crosslinking in 13C-labeled chloromethylated polystyrene-divinylbenzene resins. Our system uses a new room temperature reduction of the chloromethyl groups that circumvents the possible challenges associated with additional crosslinking. We demonstrate how the reduction of the chloromethyl groups allowed for the determination of methylene bridging, derived from the methylenebis(ethenylbenzene) crosslinker, based on the integration of the methylene signal in the 13C NMR spectra. Utilizing this method, the total crosslinking within the chloromethylated resin generated at 35 °C was determined to be upward of 10 wt %, which increased from 6 wt % in the unfunctionalized resin. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1955–1960

Augmenting the adsorption of palladium from spent catalyst using a thiazole ligand tethered on an amine functionalized polymeric resin

Palladium is an industrially important precious metal and its recovery is of utmost significance in miscellaneous applications. Polystyrene divinylbenzene resins are known for their high surface area and porosity to effectively capture metal ions after suitable modification. In this work, we report the anchoring of 2-mercaptobenzothiazole onto the amine functionalized Amberlite XAD-1180 resin for the effective adsorption of palladium. The macroreticular resin serves as a good host to welcome palladium (guest) and the proof of concept was established comprehensively using FT-IR, SEM, EDX and optical imaging analysis. The Langmuir adsorption capacity of the functionalized resin for Pd2+ acquired through the linear isotherm model was found to be 50.00mgg−1. Kinetics of the adsorption process synchronized well with the pseudo-second order model and furthermore the exergonic and endothermic nature of the adsorption process was quantified through the negative free energy and positive enthalpy values. Regeneration of the resin surface was done using thiourea and the method was tested in recovering palladium from a spent catalyst containing 5% Pd on activated carbon.

Enhancing detection coverage in untargeted metabolomics analysis by solid-phase extraction on-line coupled to LC-MS/MS.

One of the main limitations of untargeted metabolomics analysis is the low detection coverage of analytical techniques such as NMR, LC-MS, or GC-MS. In this research, the detection coverage of an automated approach configured by the on-line coupling of SPE to LC-MS/MS was evaluated by combination of sorbents based on different retention mechanisms. The approach was applied to the analysis of human serum using three types of sorbents: alkyl bonded silica, polymeric resins, and mixed-mode ionic resins. The combination of four sorbents (C18, a modified polystyrene-divinylbenzene resin and two mixed-mode ionic resins) led to the best extraction results and, therefore, the best detection coverage, which is explained by their complementary retention mechanisms. However, some of the sorbents provide a high detection coverage by themselves, as is the case with C18, which can afford to retain almost 83% of all detected entities. Taking into account the complementarity between pairs of these sorbents (C18 and the polystyrene-divinylbenzene resin with the mixed-mode ionic resins), dual cartridge SPE-LC-MS/MS configurations were designed for serum analysis. These configurations allowed increasing the detection coverage up to 91% of the total number of molecular features detected with all sorbents tested. An additional benefit of the SPE-LC-MS/MS strategy was the improvement of sensitivity as compared to protein precipitation and fractionation with methanol and chloroform. Thus, an average preconcentration factor of 10-75 was obtained in the SPE-based approach versus the two-phase protocol for metabolites extraction.