Common Solid Phase Extraction Research Articles

Direct injection UPLC-MS/MS method for analysing 77 compounds including human biomarkers, illicit drugs, new psychoactive substances and metabolites in wastewater.

Wastewater analysis technology has emerged as a promising tool for monitoring illicit drug consumption. However, the current reliance on the solid-phase extraction (SPE) pre-treatment method presents significant challenges for widespread adoption and high-throughput monitoring, as it consumes a large amount of time and labor as well as requires specialized instruments. This study has developed a direct injection (DI) technique for UPLC-MS/MS, enabling the detection of 77 compounds encompassing metabolites of human biomarkers, illicit drugs, and new psychoactive substances. The DI method underwent rigorous optimization and validation, demonstrating a lower limit of quantitation (LLOQ) ranging from 1 ng L-1 to 100 ng L-1 and a limit of detection (LOD) ranging from 0.5 ng L-1 to 80 ng L-1. The SPE method comprising two common SPE cartridges and the DI method were compared in terms of matrix effects, recoveries, and accuracies through analyzing spiked wastewater samples. The DI method exhibited superior capability in detecting a wider range of compounds while being more time-efficient, and it also significantly demonstrated a better recovery, lower matrix effect, and lower relative error in spiked samples. Real wastewater samples from 25 wastewater treatment plants (WWTPs) were analyzed using this method. This study expanded the targets species of wastewater analysis by DI method and provided practical strategies for conducting large-scale drug monitoring.

Performance of free-flow field-step electrophoresis as cleanup step for the non-target analysis of environmental water samples

For the analysis of low concentrations of micropollutants in environmental water samples, efficient sample enrichment and cleanup are necessary to reduce matrix effects and to reach low detection limits. For analytes of low and medium polarity, solid-phase extraction is used, but robust methods for the preconcentration of highly polar or ionizable analytes are scarce. In this work, field-step electrophoresis (FSE) was developed as an environmental sample cleanup technique for ionizable micropollutants and ionic transformation products. The FSE electrolyte system preconcentrated 15 acidic model analytes (pKa from −2.2 to 9.1) present in aqueous samples in two fractions by factors of 5–10. Simultaneously, highly mobile matrix compounds were removed including inorganic ions such as sulfate and chloride. The fractions were either directly injected for downstream analysis by reversed-phase liquid chromatography (RPLC) or further processed by evaporative preconcentration with subsequent reconstitution in an organic solvent suitable for separation methods like hydrophilic interaction chromatography. The FSE/RPLC-MS method exhibited high quantitative precision with RSDs of 3–6%. The method was successfully applied to a spiked river water sample and its performance compared with common solid-phase extraction and evaporative concentration, demonstrating a high analyte coverage. FSE combined with non-target screening by RPLC-MS revealed a strong reduction in matrix load especially at low retention times. Seventeen compounds were identified in the FSE fractions sampled at the field step boundary by retention time, accurate mass, and mass fragments. Suspect screening by FSE/RPLC-MS was facilitated by FSE’s selectivity for anionic compounds.

Self-supporting crumpled graphene balls as stable and reusable adsorbents for solid-phase extraction

The substantial aggregation of pristine graphene nanosheets or the possible escape of graphene from the supporting materials decreases its powerful adsorption capacity and diminishes its practical applications in graphene-based solid-phase extraction (SPE). It is highly desirable for these graphene-based adsorbents to be dispersive, stable and reusable. In this study, we report the use of self-supporting crumpled graphene balls as stable and reusable adsorbents for SPE. Comparative studies shows crumpled graphene balls are superior to other common SPE adsorbents in terms of recovery (approaching 100% for all four chlorophenols) and adsorption capacity (826.4 and 1457.4 μg/g for pentachlorophenol and 2-chlorophenol). Notably, the stability and reusability of crumpled graphene balls was remarkable due to their unique chemical structure with wrinkles and ridges. The application of the obtained crumpled graphene balls was further successfully extended to the enrichment and desalination of proteins.

Fractionation and molecular characterization of natural organic matter (NOM) by solid-phase extraction followed by FT-ICR MS and ion mobility MS

Electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been widely used for the characterization of dissolved organic matter (DOM) extracted by solid-phase extraction (SPE) from various environmental waters. It is known that common SPE generally has a relatively low recovery and the non-polar and weakly polar components are less likely to be ionized due to ionization discrimination. However, the molecular selectivity during SPE is not clear so far. In this study, the Suwannee River natural organic matter (SRNOM) was fractionated by multi-step SPE with different solvents and the fractions were characterized by negative ESI FT-ICR MS and trapped ion mobility spectrometry-mass spectrometry (IMS-MS). The sequential solvent elution increased the extraction recovery of DOM in water by SPE and enabled the characterization of a weakly polar component, which cannot be detected in common SPE separation. The weakly polar component accounts for 5.7% in TOC for the SRNOM, which has complex but different molecular composition with methanol- and/or water-eluted fractions. Lipid-like compounds were enriched in this fraction. Compared with the polar molecules directly eluted by one-step SPE from the SRNOM, the weakly polar fractions exhibit larger molecular size. The results are helpful for understanding of the molecular composition of SRNOM, as well as other environmental waters. In addition, the study demonstrates that the combination of FT-ICR MS and IMS-MS has potential to characterize the chemical composition of a complex mixture, like DOM, to a new depth. Graphical abstract.

Application of immunoaffinity purification technology as the pretreatment technology for traditional Chinese medicine: Its application to analysis of hesperidin and narirutin in traditional Chinese medicine preparations containing Citri reticulatae Pericarpium.

In the present study, the feasibility of immunoaffinity chromatography (IAC) as a purification technology for the analysis of bioactive components in Traditional Chinese Medicine (TCM) was evaluated. IAC was used to analyze hesperidin (HP) and narirutin (NR) in TCM preparations containing Citri reticulatae Pericarpium (CRP, Chenpi in Chinese). An IAC column for the specific extraction and enrichment of HP and NR from TCM preparations containing CRP was developed and characterized. After HP reacted with carbonyl diimidazole and coupled to protein, it was used to immune mice for the generation of antibody. Through cell fusion, cloning and screening, monoclonal antibody was obtained. The IAC column was constructed by covalently coupling specific monoclonal antibody against HP and NR to CNBr-activated Sepharose 4B and packed into a common solid phase extraction cartridge. The extraction conditions including loading, washing and eluting, as well as flow rate for the extraction of HP and NR were optimized. Under optimal conditions, the maximum capacity, extraction recovery rate and stability of IAC column was also characterized. Results revealed that the maximum capacity of IAC column for HP and NR was approximately 16μg and the relative binding capacity per 1mL of the column volume was 27μg. The extraction recovery rate of IAC column for HP and NR at three spiked levels was in the range of 94.05-109.15%. After the repeated application for 5 times, no significant loss of specific recognition was observed. Using high performance liquid chromatography (HPLC) as an effective analytic tool, HP and NR could be successfully separated via IAC column without the inference from impurities, suggesting that the extraction of HP and NR using the prepared IAC column is feasible. The application of IAC can solve the problem of quantitative analysis due to severe interference or low content. Furthermore, pretreatment methods in different matrixes can be unified. The IAC purification procedure can be used as an alternative effective analytical method for the pretreatment of bioactive components in TCM.

Development and Application of Immunoaffinity Column for the Simultaneous Determination of Norfloxacin, Pefloxacin, Lomefloxacin, and Enrofloxacin in Swine and Chicken Meat Samples

Immunoaffinity chromatography (IAC) for simultaneous determination of four fluoroquinolone antibiotics, e.g., norfloxacin (NOR), pefloxacin (PEF), lomefloxacin (LOM), and enrofloxacin (ENRO) from swine and chicken meat samples, was developed. The IAC column was constructed by covalently coupling polyclonal antibody (pAb) against NOR to cyanogen bromide (CNBr)-activated Sepharose 4B and packed into a common solid-phase extraction (SPE) cartridge. It was found that IAC column was able to separately capture NOR, PEF, LOM, and ENRO with a maximum capacity of 200, 336, 352, and 421 ng, respectively. The extraction conditions including loading, washing, and eluting solutions were carefully optimized. Under optimal conditions, the extraction recoveries of the IAC column for NOR, PEF, LOM, and ENRO at two different contents were within 85.8–105.9 %. The IAC column was also applied to real sample extraction. Swine and chicken meat samples were collected and spiked with NOR, PEF, LOM, and ENRO at the content of 20 and 35 ng g−1, respectively. The spiked and unspiked samples were extracted by IAC column and measured by high-performance liquid chromatography (HPLC). It was found that there was no detectable NOR, PEF, LOM, and ENRO in the blank samples, and the extraction recoveries of the IAC for NOR, PEF, LOM, and ENRO from the spiked samples were within 75.3–99.8 % with the relative standard deviation (RSD) of 4.3–12.1 %. The stability of the column was also tested. It was showed that after 30 times repeated usage, 65 % of the maximum capacity was still remained, indicating high reusability of the IAC column. The proposed IAC was proven to be an effectively selective extraction method for NOR, PEF, LOM, and ENRO from swine and chicken meat samples with the properties of high maximum capacity, extraction efficiency, and stability.

Simultaneous analysis of apolar phytohormones and 1-aminocyclopropan-1-carboxylic acid by high performance liquid chromatography/electrospray negative ion tandem mass spectrometry via 9-fluorenylmethoxycarbonyl chloride derivatization

A strategy to detect and quantify the polar ethylene precursor 1-aminocyclopropan-1-carboxylic acid (ACC) along with the more apolar phytohormones abscisic acid (ABA), indole-3-acetic acid (IAA), jasmonic acid (JA), jasmonic acid-isoleucine conjugate (JA-Ile), 12-oxo-phytodienoic acid (OPDA), trans-zeatin, and trans-zeatin 9-riboside using a single extraction is presented. Solid phase resins commonly employed for extraction of phytohormones do not allow the recovery of ACC. We circumvent this problem by attaching an apolar group to ACC via derivatization with the amino group specific reagent 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl). Derivatization in the methanolic crude extract does not modify other phytohormones. The derivatized ACC could be purified and detected together with the more apolar phytohormones using common solid phase extraction resins and reverse phase HPLC/electrospray negative ion tandem mass spectrometry. The limit of detection was in the low nanomolar range for all phytohormones, a sensitivity sufficient to accurately determine the phytohormone levels from less than 50mg (fresh weight) of Arabidopsis thaliana and Nicotiana benthamiana tissues. Comparison with previously published phytohormone levels and the reported changes in phytohormone levels after stress treatments confirmed the accuracy of the method.

Development of an immunoaffinity chromatography column for selective extraction of a new agonist phenylethylamine A from feed, meat and liver samples

Phenylethanolamine A (PA) is a new emerged β-adrenergic agonist that has been illegally used as an animal feed additive for growth promotion in China. In this study, an immunoaffinity chromatography (IAC) column for selective extraction of PA from swine feed, meat and liver samples was developed. The IAC column was constructed by covalently coupling specific polyclonal antibody (Ab) against PA to CNBr-activated Sepharose 4B and packed into a common solid phase extraction (SPE) cartridge. The extraction conditions including loading, washing and eluting solutions were carefully optimized. Under optimal conditions, the IAC column was characterized in terms of maximum capacity, selectivity, extraction recovery and stability. The maximum capacity of the ICA for PA extraction was found to be 239.4ng. For selectivity testing, 100ng of other three β-adrenergic agonists (clenbuterol, ractopamine and salbutamol) was separately loaded onto the column, and it was observed that the tested compounds could not be captured on the column, e.g. the column could only selectively recognize PA. The recovery of the IAC for PA extraction was found within 96.47-101.98% when 10, 50 and 100ng PA were separately loaded onto IAC column. The IAC column was also applied to real sample extraction. Swine feed, meat and liver samples were collected and spiked with PA in range of 1.0-20ngg(-1). The spiked and unspiked samples were extracted by IAC column and measured by high performance liquid chromatography (HPLC). It was found that there was no detectable PA in the blank samples, and the extraction recoveries of the IAC for PA from the spiked samples were within 89.48-104.89%. The stability of the column was also tested. It was showed that after 35 times repeated usage, 60% of the maximum capacity was still remained. The proposed IAC was proven to be a feasible extraction method for PA from different matrices with the properties of high maximum capacity, selectivity, extraction efficiency and stability.

Graphene nanoplatelets as a highly efficient solid-phase extraction sorbent for determination of phthalate esters in aqueous solution

Graphene nanoplatelet (GN) as a solid-phase extraction (SPE) sorbent in combination with high performance liquid chromatography has been used for the determination of five phthalate esters (PAEs) in aqueous solution. The operation parameters affecting the extraction efficiency were optimized. Comparative studies showed that GN was superior to other common SPE sorbents in terms of recovery and adsorption capacity. Under optimization conditions, detection limits of 0.09-0.33 ng mL(-1) were achieved for five PAEs and enrichment factors of 402-711 for the analytes were obtained. The proposed method was successfully applied for the determination of PAEs in tap water and drink samples with recoveries ranging from 87.7% to 100.9%.

Determination of steroids in the dissolved and in the suspended phases of wastewater and Danube River samples by gas chromatography, tandem mass spectrometry

In this paper, a new working approach is described for the analysis of steroids as environmental water pollutants. As novelty to the field, steroids were identified and quantified both in the dissolved and in the suspended phases, as their trimethylsilyl-(oxime)-ether derivatives, applying a recently developed tandem gas chromatographic mass spectrometric (GC–MS/MS) method, applying multiple reaction monitoring (MRM) acquisition, suitable for their quantitation in the low ng/L level, in wastewater and in Danube River samples.In addition to the analysis of filtrates obtained by the common solid phase extraction (SPE) enrichment, even the insoluble, isolated by filtration prior to the SPE, and usually discarded part of steroids were identified and quantified, simultaneously, for the first time. For this purpose a new, time, labor, cost efficient and quantitative, ultrasound assisted extraction process was developed.Reproducibility, reliability and practical utility of the ultrasound assisted extraction process were proved by the proportionality of the extracted suspended steroids obtained from different sample volumes: prepared from 0.5L and 1.0L influent wastewater, as well as from 3L, 5L and 10L Danube River water samples. Steroids' concentrations, identified and quantified in suspended conditions, showed proportionality, characterized with the relative standard deviation percentages (RSD%) of analyses: varying in case of Danube River water in the range of 0.92–6.0%, with an average of 4.10% RSD, while in the case of influent wastewater in the range of 1.59–5.8%, with an average of 4.03% RSD.Partition of steroids, between the dissolved and suspended phases of influent and effluent wastewaters and river water samples, meaning, the total amounts of steroids that the ecosystem is liable to, were defined in river water samples for the first time.Distribution of found steroids revealed that their considerable and/or overwhelming part (relating to their total amounts), are present in suspended phases: in average, 71% from wastewater and 64% from Danube River samples.

Establishment of an immunoaffinity chromatography for simultaneously selective extraction of Sudan I, II, III and IV from food samples

The establishment of an immunoaffinity chromatography (IAC) for simultaneously selective extraction of four illegal colorants Sudan dyes (Sudan I, II, II and IV) from food samples was described. The IAC column was constructed by covalently coupling monoclonal antibody (mAb) against Sudan I to CNBr-activated Sepharose 4B and packed into a common solid phase extraction (SPE) cartridge. It was observed that IAC column was able to separately capture Sudan I, II, III and IV with maximum capacity of 295, 156, 184 and 173 ng, respectively. The extraction conditions including loading, washing and eluting solutions were carefully optimized. Under optimal conditions, the extraction recoveries of the IAC column for Sudan I–IV at two different spiked concentrations were within 95.3–106.9%. After 50 times repeated usage, 64% of the maximum capacity was still remained. Six food samples randomly collected from local supermarket without spiking Sudan dyes were extracted with IAC column and detected by high performance liquid chromatography (HPLC). It was found that there was no detectable Sudan II, III and IV in all six food samples, but Sudan I with the content of 2.7–134.5 ng g −1 was detected in three food samples. To further verify the extraction efficiency, other three negative samples were spiked with Sudan I–IV at the concentrations of 20 ng g −1 and 50 ng g −1, which were then extracted with IAC column. The extraction recoveries and relative standard deviation (RSD) were 68.6–96.0% and 4.8–15.2%, respectively, demonstrating the feasibility of the prepared IAC column for Sudan dyes extraction.

A novel antibody immobilization and its application in immunoaffinity chromatography

A novel antibody immobilization and its application in immunoaffinity chromatography (IAC) were presented. Using acrylamide (AM) as monomer, ethylene glycoldimethacrylate (EGDMA) as cross-linker and bulk polymerization as synthetic method, we prepared a polymer in which the Cu(II) was embedded. The Cu(II)-embedded polymer was tested for its binding with protein. It was found that Cu(II)-embedded polymer displayed a strong binding with bovine serum albumin (BSA). At 80% of methanol, no BSA was released from Cu(II)-embedded polymer. The Cu(II)-embedded polymer was then used as a novel solid support for antibody immobilization. IAC column was prepared by immobilizing polyclonal antibody (pAb) against clenbuterol (CL) on Cu(II)-embedded polymer and packing the Cu(II)-embedded polymer-pAb into a common solid phase extraction (SPE) cartridge. Under optimal extraction conditions, the IAC column was characterized in terms of maximum binding capacity for target analyte, extraction efficiency and reusability. It was revealed that, for IAC column packed with 0.1 g of solid support immobilized with antibody, the maximum capacity for CL was 616 ng; the extraction recoveries of the column for CL from three spiked food samples were 84.4-95.2% with relative standard deviation (RSD) of 9.3-15.5%; after more than 30 times repeated usage, there was not significant loss of specific recognition. The results demonstrated the feasibility of the prepared IAC column for CL extraction. The proposed antibody immobilization method exhibiting the properties of simplicity, low cost, strong binding for target analyte, no leaching of antibody, etc., would be a very useful tool applied in the field of IAC.

Unexpected Role of Activated Carbon in Promoting Transformation of Secondary Amines to N-Nitrosamines

Activated carbon (AC) is the most common solid phase extraction material used for analysis of nitrosamines in water. It is also widely used for the removal of organics in water treatment and as a catalyst or catalyst support in some industrial applications. In this study, it was discovered that AC materials can catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. All 11 commercial ACs tested in the study formed nitrosamines from secondary amines. Among the different ACs, the N-nitrosodimethylamine (NDMA) yield at pH 7.5 ranged from 0.001% to 0.01% of initial amount of aqueous dimethylamine (DMA) concentration, but at 0.05-0.29% of the amount of adsorbed DMA by AC. Nitrosamine yield increased with higher pH and for higher molecular weight secondary amines, probably because of increased adsorption of amines. Presence of oxygen was a critical factor in the transformation of secondary amines, since ACs with adsorbed secondary amines dried under air for longer period of time exhibited significantly higher nitrosamine yields. The AC-catalyzed nitrosamine formation was also observed in surface water and wastewater effluent samples. Properties of AC play an important role in the nitrosamine yields. Preliminary evaluation indicated that nitrosamine formation was higher on reduced than oxidized AC surfaces. Overall, the study results show that selecting ACs and reaction conditions are important to minimize analytical errors and undesirable formation associated with nitrosamines in water samples.

Preparation and characterization of an immunoaffinity chromatography column for the selective extraction of trace contraceptive drug levonorgestrel from water samples

The preparation and characterization of an immunoaffinity chromatography (IAC) column for the specific extraction and enrichment of trace contraceptive drug levonorgestrel (LNG) from water samples were described. The IAC column was constructed by covalently coupling specific polyclonal antibody against LNG to CNBr-activated Sepharose 4B and packed into a common solid phase extraction (SPE) cartridge. The extraction conditions including loading, washing and eluting solutions, as well as the effect of flow rate on the extraction were carefully optimized. Pure water, 5% of methanol and 50% of methanol were respectively selected as loading, washing and eluting solutions, while the flow rates in the loading, washing and eluting steps were selected to be 1.0, 2.0 and 0.5 mL min −1, respectively. Under optimal conditions, the IAC column was characterized in terms of maximum capacity, extraction recovery and stability. It was found that, for IAC column packed with 0.2 g of solid support immobilized with antibody, the maximum capacity for LNG was about 260 ng. The extraction recoveries of the column for LNG at three different spiked concentrations were within 95.3–106.9%. After more than 35 times repeated usage, there was not significant loss of specific recognition. Using high performance liquid chromatography (HPLC) as an analytical tool, trace amount of LNG in the range of ng L −1 was found in river water and wastewater samples after 600-fold enrichment, demonstrated the feasibility of the prepared IAC column for LNG extraction.

Determination of ochratoxin A in Hungarian wines

Determination of ochratoxin A (OA) in musts and wines is described using high performance liquid chromatography with fluorescence detection (HPLC-FL). The applicability of common solid phase extraction cartridges with octadecyl-silica stationary phase (C 18-SPE) instead of immunoaffinity columns (IAC) for sample clean-up and preconcentration of OA is discussed. Utilizing 100-fold concentration, the detection limit and quantification limit of OA in wine were 0.024 and 0.125 ng/ml, respectively. Mean recovery amounted to 83.5%. Confirmation of the presence of OA was performed by quantitative conversion of OA into its methyl ester with BF 3/methanol. The method was successfully applied to routine analysis of 87 Hungarian must and wine samples. The method proved to be robust during the 2 weeks of routine measurements resulting in a mean recovery of 99.4% (std. dev. 2.4%, n=11) related to the first measurements on the control sample. OA was not detectable in the Hungarian wine and must samples.

Determination of radiation-induced hydrocarbons in processed food and complex lipid matrices

Detection of irradiated components in processed food with complex lipid matrices can be affected by two problems. First, the processed food may contain only a small amount of the irradiated component, and the radiation-induced hydrocarbons may be diluted throughout the lipid matrix of the whole food. Second, in complex lipid matrices, the detection of prior irradiation is often disturbed by fat-associated compounds. In these cases, common solid phase extraction (SPE) Florisil clean-up alone is inadequate in the detection of prior irradiation. Subsequent SPE argentation chromatography of the Florisil eluate allows the measurement of small amounts of irradiated lipid-containing ingredients in processed food as well as the detection of prior irradiation in complex lipid matrices such as paprika and chilli. SPE argentation chromatography is the first method available for the selective enrichment of radiation-specific hydrocarbons from even complex lipid matrices, thus enabling the detection of irradiation doses as low as 0.025 kGy. Furthermore, by using radiation-induced hydrocarbons in the detection of prior irradiation of paprika and chilli powder, a second independent method, the first being measurement of thermoluminescence, is available for the analysis of these matrices. Such analysis could be achieved by using this highly sensitive, cheap and easy to perform combined SPE Florisil/argentation chromatography method, without the need for sophisticated techniques like SFE-GC/MS or LC-GC/MS, so that highly sensitive detection of prior irradiation could be performed in almost every laboratory.