Highly selective separation and detection of cyromazine from seawater using graphene oxide based molecularly imprinted solid‐phase extraction

A novel molecularly imprinted polymer based on graphene oxide was prepared as a solid‐phase extraction adsorbent for the selective adsorption and extraction of cyromazine from seawater samples. The obtained graphene oxide molecularly imprinted polymer and non‐imprinted polymer were nanoparticles and characterized by scanning electron microscopy. The imprinted polymer showed higher adsorption capacity and better selectivity than non‐imprinted polymer, and the maximum adsorption capacity was 14.5 mg/g. The optimal washing and elution solvents for molecularly imprinted solid phase extraction procedure were 2 mL of acetonitrile/water (80:20, v/v) and methanol/acetic acid (70:30, v/v), respectively. The recoveries of cyromazine in the spiked seawater samples were in the range of 90.3–104.1%, and the relative standard deviation was <5% (n = 3) under the optimal procedure and detection conditions. The limit of detection of the proposed method was 0.7 μg/L, and the limit of quantitation was 2.3 μg/L. Moreover, the imprinted polymer could keep high adsorption capacity for cyromazine after being reused six times at least. Finally, the synthesized graphene oxide molecularly imprinted polymer was successfully used as a satisfied sorbent for high selectivity separation and detection of cyromazine from seawater coupled with high‐performance liquid chromatography.     

Solid-phase extraction of ursolic acid from herb using beta-cyclodextrin-based molecularly imprinted microspheres

A new method was employed to solid-phase extract ursolic acid from Ilex kudingcha C. J. Tseng using molecularly imprinted microspheres (MIMs) as the sorbent. Using a surface molecular imprinting technique, MIMs for ursolic acid were prepared with bonded beta-CD and acrylamide in combination based on functionalized poly(glycidyl methacrylate) microspheres (F-PGMA). Compared with non-MIMs (NIMs), MIMs showed high adsorption capacity, significant selectivity, and good site accessibility for ursolic acid. The maximum static adsorption capacities of the MIMs and NIMs for ursolic acid were 42.5 and 4.9 micromol/g, respectively. Chromatographic analysis shows that ursolic acid and oleanolic acid could be separated well when MIMs were used as the stationary phase of HPLC. The conditions of molecularly imprinted SPE (MISPE) of ursolic acid from the herb extract were optimized using different concentrations of ethanol solutions as loading, washing, and eluting solutions. The successful extraction of ursolic acid by MIMs provided a possible innovative approach to separate ursolic acid from herb.     

Molecularly imprinted polymer coating on metal‐organic frameworks for solid‐phase extraction of fluoroquinolones from water

In this work, a novel surface molecularly imprinted polymer with high adsorption capacity, high adsorption rate, and high selectivity for fluoroquinolones was prepared on the surface of UiO‐66‐NH₂, which is a kind of metal‐organic framework. The surface morphology and adsorption properties of this molecularly imprinted polymer were investigated. The maximum adsorption capacity was 99.19 mg/g, and adsorption equilibrium was achieved within 65 s. Combined with reversed‐phase high‐performance liquid chromatography, the molecularly imprinted polymer was used to selectively enrich, separate and analyze fluoroquinolones present in lake water. The results showed that the recoveries of the four fluoroquinolones were 92.6–100.5%, and the relative standard deviations were 2.9–6.4% (n = 3). The novel molecularly imprinted polymer is an excellent adsorbent and has broad application prospects in the enrichment and separation of trace analytes in complex samples.     

Synthesis of a molecularly imprinted polymer on mSiO2@Fe3O4 for the selective adsorption of atrazine

Atrazine contamination of water is of considerable concern because of the potential hazard to human health. In this study, a magnetic molecularly imprinted polymer for atrazine was prepared by the surface‐imprinting technique using Fe₃O₄ as the core, mesoporous silica as the carrier, atrazine as the template, and itaconic acid as the functional monomer. The magnetic molecularly imprinted polymer was characterized by Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and vibration‐sample magnetometry. The binding properties of the magnetic molecularly imprinted polymer toward atrazine were investigated by adsorption isotherms, kinetics, and competitive adsorption. It was found that the adsorption equilibrium was achieved within 2 h, the maximum adsorption capacity of atrazine was 8.8 μmol/g, and the adsorption process could be well described by the Langmuir isotherm model and pseudo‐second‐order kinetic model. The magnetic molecularly imprinted polymer exhibited good adsorption selectivity for atrazine with respect to structural analogues, such as cyanazine, simetryne, and prometryn. The reusability of the magnetic molecularly imprinted polymer was demonstrated for at least five repeated cycles without a significant decrease in adsorption capacity. These results suggested that the magnetic molecularly imprinted polymer could be used as an efficient material for the selective adsorption and removal of atrazine from water samples.     

Theoretical and experimental studies on the performances of barbital‐imprinted systems

By using density functional theory, we studied the interaction process between barbital and 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine in acetonitrile at 333 K. Barbital and 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine were used as the template and functional monomer, respectively. The molecularly imprinted polymer microspheres containing barbital and 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine were synthesized through precipitation polymerization. After removing the template molecule barbital, the average diameter of the obtained molecularly imprinted polymers was 1.45 μm. By optimizing the molar ratio of barbital and the 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine, the resulting molecularly imprinted polymers showed the highest adsorption for the barbital. The analysis of the Scatchard plot revealed that the dissociation constant (K_d) and apparent maximum adsorption quantity (Q_max) of the molecularly imprinted polymers were 30.69 mg/L and 8.68 mg/g, respectively. The study of selective adsorption showed that molecularly imprinted polymers exhibited higher selectivity for barbtital than that for 1,3‐dimethyl barbituric acid and pentobarbital. Herein, the studies can provide theoretical and experimental references for the barbital‐imprinted system.     

Preparation and application of magnetic molecularly imprinted polymers for the isolation of chelerythrine from Macleaya cordata

A novel type of magnetic molecularly imprinted polymer was prepared for the selective enrichment and isolation of chelerythrine from Macleaya cordata (Willd) R. Br. The magnetic molecularly imprinted polymers were prepared using functional Fe₃O₄@SiO₂ as a magnetic support, chelerythrine as template, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross‐linker. Density functional theory at the B3LYP/6‐31G (d, p) level with Gaussian 09 software was applied to calculate the interaction energies of chelerythrine, methacrylic acid and the complexes formed from chelerythrine and methacrylic acid in different ratios. The structural features and morphology of the synthesized polymers were characterized by using Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and vibration sample magnetometry. Adsorption experiments revealed that the magnetic molecularly imprinted polymers possessed rapid kinetics, high selectivity, and a higher binding capacity (7.96 mg/g) to chelerythrine than magnetic molecularly non‐imprinted polymers (2.36 mg/g). The adsorption process was in good agreement with the Langmuir adsorption isotherm and pseudo‐second‐order kinetics models. Furthermore, the magnetic molecularly imprinted polymers were successfully employed as adsorbents for the extraction and enrichment of chelerythrine from Macleaya cordata (Willd) R. Br. The results indicated that the magnetic molecularly imprinted polymers were suitable for the selective adsorption of chelerythrine from complex samples such as natural medical plants.     

Synthesis of molecularly imprinted polymer nanoparticles for the fast and highly selective adsorption of sunset yellow

Novel molecularly imprinted polymer nanoparticles were synthesized by precipitation polymerization with sunset yellow as the template and [2‐(methacryloyloxy)ethyl] trimethylammonium chloride as the functional monomer. The molecularly imprinted polymer nanoparticles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and their specific surface area and thermal stability were measured. The molecularly imprinted polymer nanoparticles had a high adsorption capacity in wide pH range (pH 1–8) for sunset yellow. The adsorption equilibrium only needed 5 min, and the quantitative desorption was very fast (1 min) by using 10.0 mol/L HCl as the eluant. The maximum adsorption capacity of the molecularly imprinted polymer nanoparticles for sunset yellow was 144.6 mg/g. The adsorption isotherm and kinetic were well consistent with Langmuir adsorption model and pseudo‐second‐order kinetic model, respectively. The relative selectivity coefficients of the molecularly imprinted polymer nanoparticles for tartrazine and carmine were 9.766 and 12.64, respectively. The prepared molecularly imprinted polymer nanoparticles were repeatedly used and regenerated ten times without significant absorption capacity decrease.     

Grafting of MIPs from PVDF Membranes via Reversible Addition-fragmentation Chain Transfer Polymerization for Selective Removal of p-Hydroxybenzoic Acid

Effective molecularly imprinted membranes(MIMs) were developed as an efficient adsorbent for the selective removal of p-hydroxybenzoic acid(p-HB) from acetylsalicylic acid(ASA, aspirin). The MIMs were grafted successfully from poly(vinylidene fluoride) microfiltration membranes via reversible addition-fragmentation chain transfer(RAFT) polymerization. The graft copolymerization of acrylic acid(AA) in the presence of template p-hydroxybenzoic acid led to molecularly imprinted polymer(MIP) film coated membranes. The obtained MIMs were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectrophotometer(FTIR) and Raman spectra, and batch mode adsorption studies were carried out to investigate the specific adsorption equilibrium, kinetics and selective recognition properties of different MIMs. The kinetic properties of the MIMs could be well described by the pseudo-second-order rate equation. Selective permeation experiments were performed to evaluate the permeation selectivity of the p-HB imprinted membranes. The observed performances of the MIMs are applicable to the further purification of aspirin.     

Preparation of magnetic molecularly imprinted polymer nanoparticles by surface imprinting by a sol–gel process for the selective and rapid removal of di‐(2‐ethylhexyl) phthalate from aqueous solution

Magnetic molecularly imprinted polymer nanoparticles for di‐(2‐ethylhexyl) phthalate were synthesized by surface imprinting technology with a sol–gel process and used for the selective and rapid adsorption and removal of di‐(2‐ethylhexyl) phthalate from aqueous solution. The prepared magnetic molecularly imprinted polymer nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and vibrating sample magnetometry. The adsorption of di‐(2‐ethylhexyl) phthalate onto the magnetic molecularly imprinted polymer was spontaneous and endothermic. The adsorption equilibrium was achieved within 1 h, the maximum adsorption capacity was 30.7 mg/g, and the adsorption process could be well described by Langmuir isotherm model and pseudo‐second‐order kinetic model. The magnetic molecularly imprinted polymer displayed a good adsorption selectivity for di‐(2‐ethylhexyl) phthalate with respect to dibutyl phthalate and di‐n‐octyl phthalate. The reusability of magnetic molecularly imprinted polymer was demonstrated for at least eight repeated cycles without significant loss in adsorption capacity. The adsorption efficiencies of the magnetic molecularly imprinted polymer toward di‐(2‐ethylhexyl) phthalate in real water samples were in the range of 98–100%. These results indicated that the prepared adsorbent could be used as an efficient and cost‐effective material for the removal of di‐(2‐ethylhexyl) phthalate from environmental water samples.     

Molecular imprinted membrane based on molecular imprinted nanoparticles polymer for separation of polycyclic aromatic hydrocarbons

The phase inversion technique was used for synthesis anthracene molecularly imprinted membrane (An–MIM) by hybridizing anthracene molecularly imprinted nanoparticles polymer (An–MINP) with cellulose acetate (CA). An–MIM gives high binding capacities toward anthracene, naphthalene, pyrene, benzo(a)pyrene, phenanthrene, and acenaphthylene. Meanwhile, cellulose acetate membrane (CAM) and none imprinted membrane give very low binding capacities toward Anthracene, Naphthalene, Pyrene, Benzo(a)pyrene, Phenanthrene and Acenaphthylene. The separation properties of An–MIM, none imprinted membrane (NIM), and CAM were investigated in terms of selectivity, rejection percentages, and concentrating factor. The optimum operation time of An–MIM was found to be 3 hr. The overall results indicated that the presence of chemical binding sites in the An–MIM plays predominating role in the separation properties. Therefore, An–MIM proved to be highly efficient for the removal of polycyclic aromatic hydrocarbons at various percentages. Copyright © 2015 John Wiley & Sons, Ltd.     

Preparation and characterization of molecularly imprinted polymers based on β‐cyclodextrin‐stabilized Pickering emulsion polymerization for selective recognition of erythromycin from river water and milk

Molecularly imprinted polymers were prepared via β‐cyclodextrin‐stabilized oil‐in‐water Pickering emulsion polymerization for selective recognition and adsorption of erythromycin. The synthesized molecularly imprinted polymers were spherical in shape, with diameters ranging from 20 to 40 µm. The molecularly imprinted polymers showed high adsorption capacity (87.08 mg/g) and adsorption isotherm data fitted well with Langmuir model. Adsorption kinetics study demonstrated that the molecularly imprinted polymers acted in a fast adsorption kinetic pattern and the adsorption features of molecularly imprinted polymers followed a pseudo‐first‐order model. Adsorption selectivity analysis revealed that molecularly imprinted polymers had a much better specificity for erythromycin than that for spiramycin or amoxicillin, and the relative selectivity coefficient values on the bases of spiramycin and amoxicillin were 3.97 and 3.86, respectively. The Molecularly imprinted polymers also showed a satisfactory reusability after four times of regeneration. In addition, molecularly imprinted polymers exhibited good adsorption capacities for erythromycin under complicated environment, that is, river water and milk. These results proved that the as‐prepared molecularly imprinted polymers is a potent absorbent for selective recognition of erythromycin, and therefore it may be a promising candidate for practical applications, such as wastewater treatment and detection of erythromycin residues in food.     

Innovative method for the enrichment of high‐polarity bioactive molecules present at low concentrations in complex matrices

Ginsenoside Rg1 is a valuable bioactive molecule but its high polarity and low concentration in complex mixtures makes it a challenge to separate Ginsenoside Rg1 from other saponins with similar structures, resulting in low extraction efficiency. The successful development of effective Rg1 molecularly imprinted polymers that exhibit high selectivity and adsorption may offer an improved method for the enrichment of active compounds. In this work, molecularly imprinted polymers were prepared with two different methods, precipitation polymerization or surface imprinted polymerization. Comparison of the adsorption abilities showed higher adsorption of the surface molecularly imprinted polymers prepared by surface imprinted polymerization, 46.80 mg/g, compared to the 27.74 mg/g observed for the molecularly imprinted polymers prepared by precipitation polymerization. Therefore, for higher adsorption of the highly polar Rg1, surface imprinted polymerization is a superior technique to make Rg1 molecularly imprinted polymers. The prepared surface molecularly imprinted polymers were tested as a solid‐phase extraction column to directionally enrich Rg1 and its analogues from ginseng tea and total ginseng extracts. The column with surface molecularly imprinted polymers showed higher enrichment efficiency and better selectivity than a C₁₈ solid‐phase extraction column. Overall, a new, innovative method was developed to efficiently enrich high‐polarity bioactive molecules present at low concentrations in complex matrices.     

Recognition characteristics of molecularly imprinted microspheres for triazine herbicides using hydrogen-bond array strategy and their analytical applications for corn and soil samples

The homogeneous molecularly imprinted microspheres (MIMs) based on a biologically inspired hydrogen-bond array were prepared using allobarbital as the novel functional monomer and divinylbenzene as the cross-linker. The host-guest binding characteristics were examined by molecular simulation and infrared spectroscopy. The resultant MIMs were evaluated using high performance liquid chromatography and solid-phase extraction. The results obtained demonstrate that the good imprinting effect and the excellent selectivity of MIMs are mainly due to the interaction involving the formation of three-point hydrogen bond between host and guest. The complete baseline separation was obtained for five triazine analogues and a metabolite on the MIM HPLC column. The MIMs were further successfully used as a specific sorbent for selective extraction of simetryne from corn and soil samples by molecularly imprinted solid phase extraction. Detection limits and recoveries were 5.8 μg/kg and 0.14 μg/kg and 87.4-105% and 94.6-101% for simetryne in corn and soil sample, respectively.     

Preparation and application of a molecularly imprinted polymer for the determination of trace metolcarb in food matrices by high performance liquid chromatography

In this article, for the first time, a molecularly imprinted polymer (MIP) for the metolcarb was prepared by bulk polymerization using metolcarb as the template, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross‐linker. The prepared polymer was characterized by FT‐IR, static and kinetic adsorption experiments, and the results showed that it has been successfully synthesized and had good selective ability for metolcarb. The MIP was applied as a sorbent in molecularly imprinted SPE coupled with HPLC‐UV for separation and determination of trace metolcarb in three kinds of food matrices at three concentration levels. Under the optimal conditions, the LODs (S/N=3) of cabbage, cucumber and pear were 7.622, 6.455 and 13.52 μg/kg, respectively, and recoveries were in the range of 68.80–101.31% with RSD (n=3) below 3.78% in all cases. To demonstrate further the selectivity of the MIP obtained, a comparison with commercially available C₁₈ SPE was performed. The results indicated that molecularly imprinted SPE showed better chromatography, better selectivity and higher recoveries for metolcarb than commercially available C₁₈ SPE.     

Facile and versatile strategy to prepare magnetic molecularly imprinted particles based on the coassembly of magnetic nanoparticles and amphiphilic random copolymers

Magnetic molecularly imprinted polymer nanoparticles for bisphenol A were prepared by coassembling magnetic nanoparticles and amphiphilic random copolymers. Under optimized conditions, bisphenol A as template molecules, magnetic molecularly imprinted polymer particles with regular morphology, small size, good monodispersity, and high content of OA‐Fe₃O₄ were prepared by the coassembly method using P(MMA‐co‐MAA) with monomer ratio of 9:1. These magnetic molecularly imprinted polymer particles could be rapidly collected by an external magnet within 1 min. The saturated adsorption capacity of the magnetic molecularly imprinted polymer for bisphenol A was 201.5 mg/g, and the imprinting factor was 2.5. The separation factors for bisphenol A to β‐estradiol, estriol, and diethylstilbestrol was 3.1, 2.9, and 3.7, respectively. Unlike assembling amphiphilic copolymer in the selective solvent, the coassembly process was simple and rapid. Therefore, the present work provided a facile and versatile approach to construct magnetic molecularly imprinted polymer nanoparticles under mild conditions.     

Preparation and characterization of molecularly imprinted microspheres for dibutyl phthalate recognition in aqueous environment

Molecularly imprinted microspheres (MIMs) were prepared by suspension polymerization for the binding and recognition of dibutyl phthalate (DBP). DBP was used as the template molecule, methacrylic acid as the functional monomer, ethylene dimethacrylate (EDMA) as the linking agent, PVA as the dispersing agent, and Span 60 as the surfactant. The MIMs were characterized with electron microscope scanning and rebinding experiments. The Scatchard plot revealed that the template‐polymer system has a two‐site binding behavior with dissociation constants of 4.05 and 0.515 mmol/L. The MIMs exhibited the highest selective rebinding to DBP at 736.85 μg/g. The recoveries of the MIM‐SPE column for DBP extraction was 94.75–101.9% with the RSD of 1.5–7.3%, indicating the feasibility of the prepared MIMs for DBP extraction. Finally, the method developed was used to analyze the trace levels of phthalate in aqueous environment samples.     

Preparation and Recognition Properties of Vanillin‐Imprinted Polymers

Some new molecularly imprinted polymers (MIPs) were prepared by different protocols involving vanillin as the imprinted molecule, methacrylic acid (= 2‐methylprop‐2‐enoic acid; MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA = 2‐methylprop‐2‐enoic acid ethane‐1,2‐diyl ester) as the cross‐linking agent. The adsorption property of the imprinted polymers was studied by UV spectrophotometry and HPLC. The results indicated that the porogen solvent had a certain influence on the adsorption performance of the polymer. The vanillin‐imprinted polymer MIP₁ prepared with MeOH as porogen, exhibited advantageous characteristics, i.e., a high binding activity, a good selectivity, and a rapid adsorption equilibrium. The binding parameters studied by Scatchard analysis established that there are two types of binding sites in MIP₁. Finally, by packing an SPE column (SPE = solid‐phase extraction) with the polymer MIP₁, the vanillin was separated and enriched successfully by this sorbent from the samples of Vanilla fragrans and beer.     

Preparation and Adsorption Characteristics of Cordycepin Molecularly Imprinted Polymers

The separation of a molecularly imprinted polymer for cordycepin was investigated. The synthesis employed cordycepin as the molecular template, alpha-methylacrylic acid as the functional monomer, glycol dimethyl acrylate as the cross-linking agent, azobisisobutyronitrile as the initiator, and tetrahydrofuran as the solvent and pore-foaming agent. The interaction between cordycepin and the functional monomer was investigated by ultraviolet-visible and infrared spectroscopy. The properties of the molecularly imprinted polymer were analyzed by scanning electron microscopy, equilibrium adsorption experiments, and the Scatchard equation. Static adsorption, solid phase extraction, and high-performance liquid chromatography experiments were employed to evaluate the adsorption properties and selective recognition characteristics. The results showed that the molecularly imprinted polymer had specific adsorption with cordycepin, and the maximum absorption capacity was 1920 µg/g. Scatchard analysis suggested that high affinity and low affinity binding sites were present. For the high affinity case, the dissociation constant and apparent maximum numbers of the binding sites were 0.0089 mmol/L and 4.78 µmol/g, respectively. The dissociation constant and apparent numbers of binding sites were 0.035 mmol/L and 6.047 µmol/g for the low affinity sites. Compared with the corresponding nonimprinted polymer, the cordycepin molecularly imprinted polymer exhibited higher adsorption and selectivity for cordycepin than structural analogs.     

Preparation of boronic acid and carboxyl-modified molecularly imprinted polymer and application in a novel chromatography mediated hollow fiber membrane to selectively extract glucose from cellulose hydrolysis

A novel boronic acid and carboxyl-modified glucose molecularly imprinted polymer were prepared through suspension polymerization, which is based on 1.0 mmol glucose as a template, 1.2 mmol methacrylamidophenylboronic acid, and 6.8 mmol methacrylic acids as monomers, 19 mmol ethyleneglycol dimethacrylate, and 1 mmol methylene-bis-acrylamide as crosslinkers. The prepared glucose-molecularly imprinted polymer had a particle size of 25–70 μm, and was thermally stable below 215°C, with a specific surface area of 174.82 m^2/g and average pore size of 9.48 nm. The best selectivity between glucose and fructose was 2.71 and the maximum adsorption capacity of glucose- molecularly imprinted polymer was up to 236.32 mg^/g which was consistent with the Langmuir adsorption model. The similar adsorption abilities in six successive runs and the good desorption rate (99.4%) verified glucose-molecularly imprinted polymer could be reused. It was successfully used for extracting glucose from cellulose hydrolysis. The adsorption amount of glucose was 2.61 mg/mL and selectivity between glucose and xylose reached 4.12. A newly established chromatography (glucose-molecularly imprinted polymer) mediated hollow fiber membrane method in time separated pure glucose from cellulose hydrolysates on a large scale, and purified glucose solution with a concentration of 3.84 mg/mL was obtained, which offered a feasible way for the industrial production of glucose from cellulose hydrolysates.     

Synthesis of ractopamine molecularly imprinted membrane and its application in the rapid determination of three β‐agonists in porcine urine samples

A novel molecularly imprinted membrane (MIM) with ractopamine (RAC) as the template and the hydrophilic PVDF membrane as the support was synthesized for the selective absorption of RAC and its structure analogues. The absorption behavior and selectivity of the MIM were studied. The experimental results showed that the MIM had the good selectivity to three β‐agonists including RAC, RIT, and formoterol (FOM) than that of nonimprinted membrane. The adsorption capacity for three compounds was above 1.88 μg/cm² of per membrane. Based on the clean‐up and enrichment of porcine urine samples with the MIM, a sensitive determination method of three β‐agonists in porcine urine samples by using MIM followed ultra performance chromatography coupled MS/MS detection was developed. The LOD and LOQ for RAC, RIT, and FOM were below 0.006 and 0.02 ng/mL, respectively. The mean recoveries, repeatability, and reproducibility of three compounds in porcine urine samples varied from 67.9 to 86.3%, from 3.3 to 10.8%, and from 5.3 to 8.5%, respectively. The presented method was applied to test 50 real porcine urine samples. It was demonstrated to be more sensitive and robust for the determination of RAC, RIT, and FOM in porcine urine.