List of Issues

Chinese Journal of Chromatography
2024, Vol. 42, No. 12
Online: 08 December 2024

Previous Issue    Next Issue



For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Articles

Select

Preparation of an amino/pentafluorophenyl dual-functional magnetic tricomponent covalent organic framework and its application in fluorobenzoic-acids adsorption WANG Yuelin, LIN Qian, GAO Jingnan, SHEN Jiwei, WEI Yinmao, WANG Chaozhan 2024, 42 (12):  1105-1116.  DOI: 10.3724/SP.J.1123.2024.05024 Abstract ( 67 )   HTML ( 13 )   PDF (5755KB) ( 51 )   Supporting Information Fluorobenzoic acids (FBAs) are important intermediates in the synthesis of many drugs, agrochemicals, and other organic compounds, and are also used as water tracers. FBAs are environmentally friendly, unnatural, have stable properties, are poorly adsorbed in aquifers, and are used in low dosages as groundwater tracers, which are their main advantages along with non-interfering diversity; as a result, their applications scope continues to expand. While FBAs are used to trace the movement of groundwater, direct analysis is often challenging owing to their low concentrations and the complexity of the groundwater matrix. Therefore, sample pretreatment for trace and ultra-trace FBAs in complex matrices is important prior to instrumental analysis. Covalent organic frameworks (COFs) are porous crystalline polymers constructed from organic units through strong covalent bonds and are characterized by low densities, large specific surface areas, permanent porosities, excellent chemical/thermal stabilities, and ease of functionalization for required purposes. In this study, we used a multivariate (MTV) strategy to construct a series of tricomponent COFs with different hydroxy/nitro ratios from 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp), 3,3'-dihydroxybenzidine (DHB), and 3,3'-dinitrobenzidine (DNB) as building blocks using Schiff-base reactions; these COFs are referred to as Tp-DHBxDNB(1-x) (x=0, 0.25, 0.5, 0.75, and 1). We then anchored pentafluorophenyl and amino groups to these COFs via post-synthetic modification; the adsorption performance of the COF-PFBx-NH2(1-x) samples prepared in this manner led to the selection of COF-PFB0.5-NH2(0.5) for its FBAs-adsorbing ability. A magnetic fluorophilic/anion-exchange/reversed-phase mixed-mode COF adsorbent (Fe3O4@COF-PFB0.5-NH2(0.5)) was prepared via an in-situ growth method using Fe3O4 nanoparticles as cores to facilitate separation of the material from solution. Notably, the Fe3O4@COF-PFB0.5-NH2(0.5) particles were very dispersible in water owing to their abundant amino groups and facilitated magnetic solid-liquid separation. In addition, Fe3O4@COF-PFB0.5-NH2(0.5) exhibited excellent operational stability for the magnetic solid-phase extraction (MSPE) of FBAs in aqueous samples. The structural properties of Fe3O4@COF-PFB0.5-NH2(0.5) were characterized using various techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffractometry (PXRD), Fourier-transform infrared spectroscopy, and the Brunauer-Emmett-Teller method, all of which revealed that Fe3O4@COF-PFB0.5-NH2(0.5) had been successfully prepared; it also has uniformly distributed mesopores and a specific surface area of 107 m2/g. Adsorption-mechanism studies revealed that Fe3O4@COF-PFB0.5-NH2(0.5) is highly adsorptive toward all four FBAs (4-fluorobenzoic acid (4-FBA), 2,3,4-trifluorobenzoic acid (2,3,4-TFBA), 2,3,4,5-tetrafluorobenzoic acid (2,3,4,5-tetra-FBA) and 3,5-bis(trifluoromethyl)benzoic acid (3,5-BTFMA)) through electrostatic, hydrogen bonding, F-F affinity, and π-π and hydrophobic interactions through synergy between the dual-functional fluorine and carboxyl binding sites, as well as the benzene rings in their skeletons. Isothermal FBAs-adsorption experiments involving Fe3O4@COF-PFB0.5-NH2(0.5) revealed maximum adsorption capacities of 73.5, 64.9, 38.4, and 253 mg/g for 4-FBA, 2,3,4-TFBA, 2,3,4,5-tetra-FBA and 3,5-BTFMA, respectively. Adsorption kinetics were also investigated, which revealed that FBAs-adsorption by Fe3O4@COF-PFB0.5-NH2(0.5) follows pseudo-second-order kinetics. Remarkably, no significant decrease in adsorption efficiency was observed after five adsorption-desorption cycles, highlighting good material reusability. We next optimized the factors that affect MSPE efficiency. Fe3O4@COF-PFB0.5-NH2(0.5) exhibited adsorption efficiencies of 85.7%, 86.5%, 94.9%, and 82.4% for 4-FBA, 2,3,4-TFBA, 2,3,4,5-tetra-FBA and 3,5-BTFMA from simulated underground water, respectively, under the optimal extraction conditions, which indicates that Fe3O4@COF-PFB0.5-NH2(0.5) holds significant potential for the separation and enrichment of FBAs in real samples.

Select

Preparation of a red-blood-cell-like surface molecularly imprinted polymer and its application to the selective enrichment of tetracycline in milk SHANG Jian, MA Linzhi, LEI Chao, SU Xinke, LIU Yu, WANG Yue, GAO Ruixia 2024, 42 (12):  1117-1125.  DOI: 10.3724/SP.J.1123.2024.06008 Abstract ( 86 )   HTML ( 13 )   PDF (3991KB) ( 37 )   The adsorption capacity per unit mass of a molecularly imprinted polymer is an important indicator for evaluating the adsorption performance of an imprinted material. Inspired by the large specific surface areas and excellent stabilities of double concave circular red-blood-cell discs, we synthesized a highly selective red-blood-cell-like surface molecularly imprinted polymer (RBC-SMIP) with a large adsorption capacity and a fast mass-transfer rate for tetracycline. This work used SiO2 as the initial carrier and tetracycline, a broad-spectrum antibiotic, as the template molecule. Inexpensive and readily available dopamine functional monomers were subsequently coated on the surface of the SiO2 carrier using surface molecular imprinting technology, after which the initial SiO2 carrier was etched and removed using sacrificial-carrier-etching technology, with the dosage and coating time of the dopamine imprinting layer adjusted to regulate the morphology of the prepared imprinted material. An RBC-SMIP with a large specific surface area and excellent selective adsorption performance was finally prepared. Scanning electron microscopy (SEM) and infrared (FT-IR) spectroscopy, as well as N2-adsorption-desorption, kinetics, thermodynamics, selectivity, and reusability experiments confirmed that the material had successfully been coated the imprinted polydopamine layer, and that the prepared material contained particles of uniform size and exhibited a good specific surface area and pore volume, a rapid adsorption-equilibrium time (15 min), and excellent reusability. The RBC-SMIP exhibited a unit-mass adsorption capacity and imprinting factor of 76.16 mg/g and 3.62, respectively. The successful preparation of the RBC-SMIP provides a new approach for the selective adsorption and determination of trace tetracycline contents in environmental water. In addition, combining the RBC-SMIP (as a solid-phase extractor) with HPLC led to a method with a high linear correlation coefficient (R2>0.9995) in the 0.01-200 μg/mL linear range. Average recoveries of 92.1%-95.3% were determined at three spiked levels (0.01, 0.05, and 0.10 μg/mL), highlighting the ability of the method to efficiently adsorb, enrich, and detect tetracycline in milk samples. The red-blood-cell-like surface molecularly imprinted polymer developed in this work is expected to have significant practical applications.

Select

Screening of cyclooxygenase-2 inhibitors in Panax notoginseng leaves based on ligand fishing technique ZHANG Fan, WANG Wei, CAO Ying, ZHANG Yi, WU Lijie 2024, 42 (12):  1126-1135.  DOI: 10.3724/SP.J.1123.2024.07003 Abstract ( 47 )   HTML ( 14 )   PDF (4162KB) ( 21 )   Human health is increasingly affected by chronic inflammation, which can subsequently develop into chronic diseases such as cancer, arthritis, diabetes, and diseases of the cardiovascular and nervous systems. Traditional non-steroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygenase-1 (COX-1) produce side effects, such as irritation of the gastrointestinal tract and renal toxicity. While commercially available inhibitors of the cyclooxygenase-2 (COX-2) enzyme, such as meloxicam and celecoxib, treat inflammation more-effectively than traditional NSAIDs, they associate with liver-toxicity and cardiovascular-disease risks. Modern pharmacological studies have shown that Panax ginseng, Panax notoginseng, and other traditional Chinese medicines have anti-inflammatory properties; these medicines mainly contain flavonoids, alkaloids, saponins, polysaccharides, and other anti-inflammatory components, are highly efficient, and exhibit few side effects, which is advantageous. Therefore, screening potential COX-2 inhibitors from traditional Chinese medicine is greatly significant for the development of safe and effective novel anti-inflammatory drugs. However, screening these traditional medicines in an easy, quick, accurate, and efficient manner presents problem that require urgent solutions because traditional screening methods are cumbersome and inefficient. In this study, we used the ligand fishing method instead of poorly efficient traditional screening methods, with magnetic nanoparticles used as the carrier owing to their advantageous fast separation speeds. In addition, we also maintained the spatial structure and activity of the fixed enzyme by combining immobilized metal affinity technology, and selected polydopamine (PDA) as a low-toxicity metal-chelating agent owing to its strongly adhesive nature and good chelating ability for various metal ions. The application of PDA solves the problems of metal-ion leakage and limited protein load associated with traditional chelating agents. Firstly, magnetic Fe3O4 nanoparticles were hydrothermally synthesized, after which their surfaces were coated with PDA using the magnetic-stirring method, with Ni2+ then chelated on the PDA surface and COX-2 fixed through metal-ion affinity, to afford a convenient, fast, green, and specific fishing tool. The structure and properties of the magnetic nanomaterial were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, vibrating sample magnetometry (VSM), and other methods. The magnetic nanomaterials have core-shell structures with particles that are 250-300 nm in size; they also have a large specific surface area, are strongly magnetic, highly stable, and perform excellently. Celecoxib, a selective COX-2 inhibitor, was used as a fishing target during optimization of the fixed-COX-2 and fishing conditions, including the adsorption and elution conditions. The optimal settings were then successfully used to screen potential COX-2 inhibitors in Panax notoginseng leaves. Methodological experiments revealed that the instrument and method are highly precise, accurate, and repeatable, with a limit of detection (LOD) of 0.02 mg/mL and a limit of quantification (LOQ) of 0.07 mg/mL. Only celecoxib was detected in a fishing solution composed of glipizide, indomethacin, and celecoxib, which implies that immobilized COX-2 exhibits good fishing specificity, and that only components that strongly interact with COX-2 are caught. Thirteen components that interact with COX-2 were identified by liquid chromatography-mass spectrometry for a fishing solution of Panax notoginseng leaves, including notoginsenoside Fa and ginsenoside Rb1, which are expected to be COX-2 inhibitors. Compared with traditional screening methods, the method developed in this study is simple, rapid, and highly specific and enzyme active, leading to the capture and enrichment of the specific target. This study provides guidance for the synthesis and development of new safe and effective anti-inflammatory drugs, and provides a reference for the efficient discovery of such drugs or lead compounds from complex traditional Chinese medicines; it also provides a new concept for the rational utilization of Panax notoginseng leaves.

Select

Determination of 66 pesticide residues in Litopenaeus vannamei by high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry based on modified multi-wall carbon nanotube purification ZHOU Ruidong, WEN Yupeng, HUO Wendi, ZHANG Chaoying, LIU Huan, SUN Huiwu, WU Lidong, LI Jincheng 2024, 42 (12):  1136-1144.  DOI: 10.3724/SP.J.1123.2023.12021 Abstract ( 46 )   HTML ( 15 )   PDF (2868KB) ( 32 )   The complex composition of aquatic products, with high levels of protein and fat, significantly impacts the accuracy of liquid chromatography-mass spectrometry analysis for pesticide residue detection. Hence, developing effective purification materials is essential to mitigate these matrix interferences. To address strong matrix interference in pesticide residue analysis, a composite material, multi-walled carbon nanotubes (MWCNTs)-sodium alginate (SAL) (MWCNTs-SAL), was developed and used as purification material in a push-rod oscillation purification column to establish a rapid method for analyzing 66 pesticide residues in Litopenaeus vannamei. The composite solution of MWCNTs and SAL was quickly sprayed into CaCl2 solution by electrospray device for crosslinking, and MWCNTs-SAL materials were prepared. The results of scanning electron microscopy image proved the successful preparation of the MWCNTs-SAL. Acetonitrile, as the extraction solvent, was modified with acetic acid to augment the extraction efficiency of acidic pesticides, and anhydrous sodium sulfate was utilized to remove water from the matrix. Push-rod oscillation purification technology was used for purification of the post-centrifugation extract. The target compounds were separated using C18 RRHD column (150 mm×3.0 mm, 1.8 μm) and the mobile phases were consisted of 0.2% formic acid aqueous solution (containing 5 mmol/L ammonium acetate) and 0.2% formic acid methanol. The high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry (HPLC-QTRAP-MS/MS) was used for separation and determination, and the data was collected through the multiple reaction monitoring (MRM) mode. Due to the different properties of the target compounds, positive and negative ion acquisition scan modes were employed for mass spectrometry analysis. The quantitative analyses of the 66 pesticides were achieved by matrix-matched standard curves. The purification effects of MWCNTs-SAL and commercial sorbents on the extraction of the 66 pesticides were compared. The pretreatment parameters, such as the optimal dosage of MWCNTs-SAL and anhydrous sodium sulfate on the purification effects of the 66 pesticides were also assessed. When using 50 mg MWCNTs-SAL and 100 mg anhydrous sodium sulfate as the purification materials, the purification effect of aquatic products was the best. The 66 pesticides demonstrated good linearities in the range of 0.5-50 μg/L, with correlation coefficients of greater than 0.99. The limits of detection and quantification for the 66 pesticides were 0.5-1 μg/kg and 1-2 μg/kg, respectively. The recoveries of the 66 pesticides under three spiked levels (low, medium, high) were 64.1%-107.3%. The intra- and inter-day precisions were both less than 20.4%. This study provides an economical, quick, efficient, and sensitive approach for pesticide residue detection in aquatic products.

Select

Construction of an alternating reversed-phase and hydrophilic interaction liquid chromatography-tandem mass spectrometry dual mode chromatography system and its application in comprehensive metabolite profiling analysis HUANG Yan, ZHANG Xing, JIANG Tingting, ZHOU Yawen, JIANG Peng, YIN Hongfeng, TANG Tao 2024, 42 (12):  1145-1152.  DOI: 10.3724/SP.J.1123.2024.05010 Abstract ( 69 )   HTML ( 8 )   PDF (1133KB) ( 19 )   As one of the youngest “omics” disciplines, metabolomics, more specifically, metabolite profiling, enables the comprehensive quantitative analysis of a primary metabolome. At present, comprehensive metabolite profiling analysis is a challenging task owing to the greatly different physicochemical properties of metabolites and the complexity of sample matrices, especially given the wide variety of biological samples. Consequently, the development of a multimodal separation method with higher metabolite coverage than single-mode chromatography is necessary for comprehensive metabolite profiling analysis and biomarker discovery. Reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) are used to analyze nonpolar and polar metabolites, respectively. HILIC and RPLC separation results are commonly combined to achieve comprehensive metabolite profiling analysis. However, this practice leads to overlapping datasets and extended analysis times. Alternatively, multiple LC systems can be coupled to generate combined HILIC and RPLC separation results. In this study, we developed an alternating HILIC/RPLC-tandem mass spectrometry (MS/MS) dual-mode separation system consisting of one autosampler, two high-pressure LC pumps, a HILIC column, an RP column, a 6-port 2-position switching valve, a 10-port 2-position switching valve, and a mass spectrometer for the comprehensive and high-throughput analysis of polar and nonpolar metabolites. In this configuration, the autosampler is always on the same flow path as the mass spectrometer, whereas the HILIC and RP columns are switched in and out of the main flow path. At the initial stage of the analysis, the autosampler is connected to a HILIC column, followed by the mass spectrometer. While gradient elution is performed on the HILIC column, the RP column is equilibrated using the second high-pressure pump. After HILIC separation, the 6-port 2-position and 10-port 2-position switching valves are switched simultaneously. At this stage of the analysis, the autosampler is connected to the RP column, followed by the mass spectrometer, while the HILIC column is equilibrated. This process is repeated for the subsequent samples. Because the equilibration time of one column overlaps with the gradient elution of the other column, the total analysis time can be reduced by approximately 40%. This system was used to analyze 14 representative endogenous metabolites, including four common types: organic acids, amino acids, choline, and lysophospholipids. The alternating HILIC/RPLC-MS/MS dual-mode separation system had high metabolite coverage and could analyze all 14 representative metabolites simultaneously. By contrast, only 10 of the 14 metabolites could be analyzed using the HILIC-only system. The HILIC-only system failed to analyze organic acids. On the other hand, the RP-only system failed to analyze hydrophilic amino acids, choline, and lysophospholipids. These findings indicate that only 6 of the 14 representative metabolites could be analyzed by the RP-only system. Method validation was conducted to ensure the accuracy of the proposed method. Fourteen representative metabolites were spiked into a urine matrix for validation. All 14 metabolites exhibited linear responses, with correlation coefficients greater than 0.99. The limits of detection (LODs) were in the range of 0.02-42.86 ng/mL, and the limits of quantification (LOQs) were in the range of 0.08-142.86 ng/mL. The average recoveries at three spiked levels were in the range of 85.2%-113.9%. The intra- and inter-day precisions (RSDs) were less than 10%. The proposed instrument configuration and dual-mode method are practical and easy to use for metabolite profiling research in clinical applications such as disease diagnosis, drug development, and biomarker discovery. Furthermore, the proposed instrument configuration and method could potentially be used to analyze other complex samples in proteomics and glycomics research.

Select

Simultaneous determination of 100 glucocorticoids in cosmetics using ultra performance liquid chromatography-tandem mass spectrometry SHEN Dandan, GONG Shanshan, JIANG Bohai, LI Yuechen, XUE Hengyue, YU Bentao, KE Yifan, LI Zhiyuan, MAO Xiqin 2024, 42 (12):  1153-1163.  DOI: 10.3724/SP.J.1123.2024.03011 Abstract ( 81 )   HTML ( 7 )   PDF (1010KB) ( 53 )   Adding glucocorticoids to cosmetics is strictly prohibited under Safety and Technical Specification for Cosmetics (2015) regulations. Accordingly, a method for simultaneously determining 100 glucocorticoids in cosmetics using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Apart from the 58 glucocorticoids listed in the two current national standards (GB/T 24800.2-2009 and GB/T 40145-2021) and the Safety and Technical Specification for Cosmetics (2015) regulations, 42 new glucocorticoids, including unreported metenolone acetate and dexamethasone 9,11-epoxide, were included in this method. Samples were dispersed in saturated sodium chloride containing 0.2% (v/v) acetic acid, and extracted with acetonitrile containing 0.2%(v/v) acetic acid. After that, an equal volume of water was added to the acetonitrile extraction solution to precipitate non-polar impurities. The solution was subsequently further purified using 10%(mass fraction) potassium ferrocyanide solution and 20%(mass fraction) zinc acetate solution containing 0.4% (v/v) acetic acid as precipitants. The sample solution was finally loaded onto a Waters ACQUITY UPLC BEH C18 column (150 mm×3.0 mm, 1.7 μm) and gradient-eluted using aqueous and methanolic 0.2% (v/v) acetic acid solutions as mobile phases. The target compounds exhibited highly intense signals in positive electrospray-ionization mode. All compounds were analyzed in multiple reaction monitoring mode (MRM) and quantified using the external standard method. Rimexolone and hydrocortisone hemisuccinate hydrate exhibited peaks corresponding to their [M-H2O+H]+ base ions, whereas the other 98 glucocorticoids exhibited [M+H]+ peaks. All positive samples were confirmed by their automated MRM-based information dependent acquisition (IDA) enhanced product ions (EPIs). Highly sensitive secondary mass spectra were acquired when EPI mode was combined with IDA and when target compounds in positive samples were located in MRM mode, with compounds further confirmed by matching their secondary mass spectra with those of the corresponding standard glycocorticoids using the Library Search function in SCIEX OS software. Matrix effects (MEs) were investigated in water- and cream-based cosmetics by adding standard compounds to the extracted-matrix solutions. Ciclesonide exhibited no obvious matrix effect with a ME of 3.4% in the water-based matrix whereas it exhibited a serious inhibitory effect with a ME of 30.6% in the cream-based matrix. The remaining 99 target compounds exhibited MEs of -7.9%-12.4%, which are not significant because they are below 15%, further confirming that the sample-pretreatment method is effective and feasible. Therefore, ciclesonide in a cream-based matrix was quantified using a matrix-matched standard curve, while the others were quantified using solvent standard curves. The 100 glucocorticoids exhibited good linearities with correlation coefficients (r) of >0.99 in the range of 2.5-60 ng/mL. The limits of detection (LODs) and limits of quantification (LOQs) of this method were 0.03 and 0.1 μg/g, respectively. Recovery tests were performed at three spiked levels, namely one-, two-, and eight-times the LOQs. The 100 compounds exhibited recoveries of 79.6%-114.4% with relative standard deviations (RSDs) of 0.7%-9.4% (n=6) in water-based cosmetics; in comparison, they exhibited recoveries of 79.5%-112.1% with RSDs of 0.7%-12.9% (n=6) in cream-based cosmetics. Three cream-based positive samples were identified among 47 batches of cosmetics samples (including 25 batches of cream and lotion-based cosmetics, and 22 batches of water-based cosmetics), with quantitative analysis revealing five positive compounds: triamcinolone acetonide (115.1 μg/g), triamcinolone acetonide 21-acetate (0.6 μg/g), clobetasol propionate (24.5 μg/g), dexamethasone (2.7 μg/g), and dexamethasone-17-acetate (210.3 μg/g). These five compounds were further confirmed using MRM-IDA-EPI. The secondary mass spectra of the five compounds showed high matching degrees (>96%) with those of the corresponding standard glucocorticoids in the library database. In conclusion, the method developed in this study is simple, practical, inexpensive, highly efficient, and suitable for qualitatively and quantitatively screening and analyzing 100 glucocorticoids in cosmetics, thereby filling supervisory gaps and greatly improving the detectability of glucocorticoids illegally added to cosmetics.

Select

Simultaneous determination of eight antiviral drugs and two metabolites in Chinese softshell turtles using pass-through solid-phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry WANG Yaqin, WANG Kun, KE Qingqing, TAN Yuchong, WANG Dingnan, LI Shiyan 2024, 42 (12):  1164-1172.  DOI: 10.3724/SP.J.1123.2024.02011 Abstract ( 45 )   HTML ( 5 )   PDF (2132KB) ( 33 )   Antiviral drugs (ATVs) are not licensed for the treatment of viral diseases in food-producing animals in China. However, they are reportedly illegally used in the Chinese softshell turtle (Pelodiscus sinensis) aquaculture industry; hence, the use of ATVs has become a new aquatic food-safety problem. In this study, a method was developed for analyzing eight ATV residues (amantadine, rimantadine, lamivudine ribavirin, moroxydine, acyclovir, oseltamivir, and imiquimod) and two metabolites (1,2,4-triazole-3-carboxamide and oseltamivir acid) in Chinese softshell turtle muscle using pass-through solid-phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The main factors that affect the sensitivity, precision, and accuracy of the method were optimized during sample pretreatment and instrumental analysis owing to the diverse chemical properties of the analytes. The performance of various chromatographic columns and mobile phases were investigated to eliminate interference from uridine during the detection of ribavirin. The proportion of acetonitrile in extration solution and solid-phase extraction column type were prioritized when optimizing extraction and purification parameter. Samples were hydrolyzed using phosphatase (acid type) in 6 mL ammonium acetate buffer, with optimum results obtained when enzymolysis was performed at 37 ℃, and pH 4.8 for 2 h, after which they were extracted with 14 mL of acetonitrile containing 1% acetic acid. The supernatant (2 mL) was purified using a Wallelut Lipoclean column operated in pass-through solid-phase-extraction mode. The sample was dried under nitrogen at 40 ℃ and the residue was dissolved in 1 mL of methanol-acetonitrile (50∶50, v/v) solution. The sample was finally filtered through a 0.22-μm hydrophilic polytetrafluoroethylene syringe filter for UHPLC-MS/MS. The chromatographic separation of the analytes was performed on a hydrophilic interaction chromatographic column (HILIC-Z, 100 mm×2.1 mm, 2.7 μm) via gradient elution using 2 mmol/L ammonium acetate aqueous solution (containing 0.1% formic acid) and acetonitrile as mobile phases A and B, respectively. The linear gradient program were as follows: 0-1.0 min, 3%A; 1.0-5.0 min, 3%A-20%A; 5.0-6.0 min, 20%A; 6.0-6.5 min, 20%A-50%A; 6.5-8.0 min, 50%A; 8.0-8.5 min, 50%A-3%A; 8.5-12 min, 3%A. The analytes were detected using a triple quadrupole mass spectrometer operating in positive-ion scanning and multiple-reaction monitoring (MRM) modes, with quantitative analysis performed using the internal standard method. Good linearities (r2=0.994-0.998) were obtained for the ten target compounds at experimental concentrations under the optimal conditions. The method detection limits (MDLs) and method quantification limits (MQLs) were in the range of 0.05-1.1 and 0.18-3.8 μg/kg, respectively. The average recoveries of the 10 target compounds ranged from 82.5% to 103%, with relative standard deviations (RSDs) in the range of 3.11%-12.1% at low, medium and high spiked levels. The developed method was applied to 67 Chinese softshell turtle samples obtained from a fish farm in Zhejiang Province. Ribavirin and metabolite were detected in real samples at total contents of 6.02-333.2 μg/kg. The developed method is simple to operate, highly accurate, and suitable for use in risk-monitoring applications owing to its ability to rapidly determine eight ATV residues and two metabolites in Chinese softshell turtle samples.

Select

Determination of 60 steroid hormones in sports nutrition foods by ultra performance liquid chromatography-tandem mass spectrometry CAI Xiaoming, WU Shaoming, YU Qing, HUANG Hehe, ZHENG Qiuping, HE Menghang, DAI Ming, OUYANG Liqun 2024, 42 (12):  1173-1188.  DOI: 10.3724/SP.J.1123.2024.03020 Abstract ( 85 )   HTML ( 11 )   PDF (1888KB) ( 46 )   Recent societal developments and improving living standards have witnessed a growing enthusiasm for sport and fitness along with a boom in sports nutrition foods. However, rapid industrial development has led to product quality and safety issues becoming increasingly important. Steroid hormones exhibit physiological effects that include promoting protein synthesis, increasing muscle mass, and reducing body fat. Driven by vested interests, some unscrupulous traders illegally add steroid hormones to sports nutrition foods to improve sports performance and relieve muscle pain, which poses a potential threat to human health. Therefore, establishing a method for determining steroid hormones in sports nutrition foods is of great practical importance. In this study, an analytical method for the simultaneous determination of 60 steroid hormones in sports nutrition foods was developed using QuEChERS combined with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The MS parameters and chromatographic conditions were optimized for the 60 steroid hormones, and the extraction solvents and purification methods were systematically optimized to facilitate rapid screening and accurate quantitative analysis of these hormones in sports nutrition foods. Samples were extracted with 1.0% formic acid in methanol, partitioned with sodium chloride, and purified using 150 mg of PSA and 150 mg of C18 powder. The clean-up solution was evaporated to near dryness under a stream of nitrogen and the residue was reconstituted with 50% methanol aqueous solution. The 60 target compounds were separated on a Waters Acquity UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) with 0.1% (v/v) formic acid aqueous solution (containing 10 mmol/L ammonium acetate) and methanol as the mobile phases. The analytes were determined by multiple reaction monitoring (MRM) in positive electrospray ionization mode (ESI+) and quantified using the external standard method. The method was validated under the optimized conditions, with the 60 steroid hormones found to exhibit good linearities in the 1.0-100 ng/mL range with correlation coefficients (r) greater than 0.99. The limits of detection (LODs) and limits of quantification (LOQs) were 0.2-0.8 μg/kg and 0.6-2.4 μg/kg, respectively. At three spiked levels on whey protein powder (solid), pectin protein peptide (semi-solid) and energy drink (liquid) as blank matrix, the mean recoveries of the 60 steroid hormones were 73.7%-112.7% with relative standard deviations (RSDs) of 3.2%-10.1% (n=6). Thirteen batches of commercially available sports nutrition products were screened using the newly developed method, with five positive samples detected. Progesterone (an endogenous hormone) was detected at levels of 12.6-25.4 μg/kg in four samples of whey protein powder, and boldenone (which is a prohibited drug for athletes) was detected at 14.6 μg/kg in one sports nutrition liquid, confirming that illegal steroid hormones are indeed added to sports nutrition foods; consequently, relevant national departments need to strengthen their monitoring of such substances in such foods. The developed method is simple, efficient, sensitive, reproducible, and suitable for the rapid screening and quantitative analysis of steroid hormones in sports nutrition foods, thereby providing technical support for the daily supervision of steroid hormones in these foods.

Select

Graphitic carbon nitride/metal-organic framework microextraction fiber for enriching volatile organic compounds in the exhaled breath of patients with lung cancer HAO Qilong, WANG Jing, YU Liqing, ZHANG Haixia 2024, 42 (12):  1189-1195.  DOI: 10.3724/SP.J.1123.2024.03002 Abstract ( 67 )   HTML ( 15 )   PDF (4927KB) ( 15 )   Volatile organic compounds (VOCs) in human exhaled breath can act as biochemical indicators for the objective determination and evaluation of physiological or pathological conditions. In humans, the pathophysiology associated with malignant tumors causes metabolic changes that alter the types and concentrations of VOCs in exhaled breath. However, as exhaled breath has a complex composition and low VOC content, meeting the direct detection requirements of analytical instruments is difficult. Therefore, the direct detection of VOCs in exhaled breath requires the development of a simple, fast, and efficient enrichment technique. In this study, graphitic carbon nitride (g-C3N4) and the metal-organic framework UiO-66 were combined to prepare a three-dimensional nanoflower-like g-C3N4/UiO-66 solid-phase microextraction (SPME) coating. The g-C3N4/UiO-66 composite was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. UiO-66, which exhibited a regular ortho-octahedral structure with sharp corners, was embedded among g-C3N4 nanoflowers, and the surface was encapsulated in g-C3N4 to form a hydrophobic barrier. Five biomarkers (benzene, toluene, ethylbenzene, o-xylene, and decanal) in the exhaled breath of patients with lung cancer were enriched using the developed SPME fiber and then detected using gas chromatography-mass spectrometry. The optimum extraction time and temperature of the nanoflower-like SPME fiber were 10 min and 60 ℃, respectively, whereas the optimum desorption time and temperature were 3 min and 260 ℃, respectively. The adsorption efficiencies of the g-C3N4/UiO-66 composite coating, a single UiO-66 coating, and a 30 μm polydimethylsiloxane commercial coating were compared under optimal conditions. The five VOCs showed good linearity in the investigated concentration ranges, with correlation coefficients of 0.9919-0.9977, limits of detection of 0.16-4.50 μg/L, and limits of quantification of 0.54-9.18 μg/L. The intra- and inter-day precisions for six parallel determinations with the SPME fiber were 3.3%-7.3% and 4.0%-6.6%, respectively. Owing to the presence of nanoflower-like interlayer channels and g-C3N4 micropores in g-C3N4/UiO-66, the composite coating exhibited a high enrichment efficiency and good repeatability. The spiked recoveries of the five VOCs were in the range of 84.6%-113.2%. Finally, the method was applied to analyze exhaled breath for the detection of lung cancer. The benzene contents in the exhaled breath of both healthy individuals and patients with lung cancer were generally low. However, the toluene contents differed significantly, with patients with lung cancer having much higher levels than healthy individuals. The established method is expected to provide a reference for the noninvasive early diagnosis of lung cancer.