Chinese Journal of Chromatography

2023, Vol. 41, No. 3
Online: 08 March 2023

CN 21-1185/O6
ISSN 1000-8713
Editors-in-Chief: Prof. Yukui Zhang
For Selected: Toggle Thumbnails
Investigation of the chemical components of Ciwujia injection using ultra-high performance liquid chromatography-quadrupole-electrostatic field orbitrap high-resolution mass spectrometry
YU Wenyi, WU Huimin, GUO Xiujie, YAN Shumei, LIU Xiangjie, WANG Zhujun, WANG Chaoran, SHEN Aijin, LIANG Xinmiao
2023, 41 (3):  207-223.  DOI: 10.3724/SP.J.1123.2022.06005
Abstract ( 65 )   HTML ( 15 )   PDF (5618KB) ( 28 )  

Ciwujia injection is commonly used to treat cerebrovascular and central nervous system diseases in clinical practice. It can significantly improve blood lipid levels and endothelial cell function in patients with acute cerebral infarction and promote the proliferation of neural stem cells in cerebral ischemic brain tissues. The injection has also been reported to have good curative effects on cerebrovascular diseases, such as hypertension and cerebral infarction. At present, the material basis of Ciwujia injection remains incompletely understood, and only two studies have reported dozens of components, which were determined using high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF MS). Unfortunately, the lack of research on this injection restricts the in-depth study of its therapeutic mechanism.
In the present study, a qualitative method based on ultra-high performance liquid chromatography-quadrupole-electrostatic field orbitrap high-resolution mass spectrometry (UHPLC-Q/Orbitrap HRMS) was developed to analyze the chemical components of Ciwujia injection. Separation was performed on a BEH Shield RP18 column (100 mm×2.1 mm, 1.7 μm) using 0.1% formic acid aqueous solution (A) and acetonitrile (B) as the mobile phases, and gradient elution was performed as follows: 0-2 min, 0%B; 2-4 min, 0%B-5%B; 4-15 min, 5%B-20%B; 15-15.1 min, 20%B-90%B; 15.1-17 min, 90%B. The flow rate and column temperature were set to 0.4 mL/min and 30 ℃ respectively. MS1 and MS2 data were acquired in both positive- and negative-ion modes using a mass spectrometer equipped with an HESI source. For data post-processing, a self-built library including component names, molecular formulas, and chemical structures was established by collecting information on the isolated chemical compounds of Acanthopanax senticosus. The chemical components of the injection were identified by comparison with standard compounds or MS2 data in commercial databases or literature based on precise relative molecular mass and fragment ion information. The fragmentation patterns were also considered. For example, the MS2 data of 3-caffeoylquinic acid (chlorogenic acid), 4-caffeoylquinic acid (cryptochlorogenic acid), and 5-caffeoylquinic acid (neochlorogenic acid) were first analyzed. The results indicated that these compounds possessed similar fragmentation behaviors, yielding product ions at m/z 173 and m/z 179 simultaneously. However, the abundance of the product ion at m/z 173 was much higher in 4-caffeoylquinic acid than in 5-caffeoylquinic acid or 3-caffeoylquinic acid, and the fragment signal at m/z 179 was much stronger for 5-caffeoylquinic acid than for 3-caffeoylquinic acid. Four caffeoylquinic acids were identified using a combination of abundance information and retention times. MS2 data in commercial database and literature were also used to identify unknown constituents. For example, compound 88 was successfully identified as possessing a relative molecular mass and neutral losses similar to those of sinapaldehyde using the database, and compound 80 was identified as salvadoraside because its molecular and fragmentation behaviors were consistent with those reported in the literature. A total of 102 constituents, including 62 phenylpropanoids, 23 organic acids, 7 nucleosides, 1 iridoid, and 9 other compounds, were identified. The phenylpropanoids can be further classified as phenylpropionic acids, phenylpropanols, benzenepropanals, coumarins, and lignans. Among the detected compounds, 16 compounds were confirmed using reference compounds and 65 compounds were identified in Ciwujia injection for the first time. This study is the first to report the feasibility of using the UHPLC-Q/Orbitrap HRMS method to quickly and comprehensively analyze the chemical components of Ciwujia injection. The 27 newly discovered phenylpropanoids provide further material basis for the clinical treatment of neurological diseases and new research targets for the in-depth elucidation of the pharmacodynamic mechanism of Ciwujia injection and its related preparations.

Determination of phenoxyacetic herbicides, metabolites of organophosphorus and pyrethroid pesticides in human urine using solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry
ZHANG Xu, HAN Linxue, QIU Tian, HU Xiaojian, ZHU Ying, YANG Yanwei
2023, 41 (3):  224-232.  DOI: 10.3724/SP.J.1123.2022.05005
Abstract ( 83 )   HTML ( 12 )   PDF (2173KB) ( 35 )  

Pesticides are widely used in most agricultural areas to protect food crops but adversely affect ecosystems and human beings. Pesticides have attracted great public concern due to their toxic properties and ubiquitous occurrence in the environment. China is one of the largest users and producers of pesticides globally. However, limited data are available on pesticide exposure in humans, which warrants a method for quantification of pesticides in human samples. In the present study, we validated and developed a comprehensive and sensitive method for the quantification of two phenoxyacetic herbicides, two metabolites of organophosphorus pesticides and four metabolites of pyrethroid pesticides in human urine using 96-well plate solid phase extraction (SPE) coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). For this purpose, a systematic optimization of the chromatographic separation conditions and MS/MS parameters was conducted. Six solvents were optimized for the extraction and clean-up of human urine samples. The targeted compounds in the human urine samples were well separated within 16 min in one analytical run. A 1 mL aliquot of human urine sample was mixed with 0.5 mL sodium acetate buffer (0.2 mol/L) and hydrolyzed by β-glucuronidase enzyme at 37 ℃ overnight. The eight targeted analytes were extracted and cleaned using an Oasis HLB 96-well solid phase plate and eluted with methanol. The separation of the eight target analytes was performed on a UPLC Acquity BEH C18 column (150 mm×2.1 mm, 1.7 μm) with gradient elution using 0.1% (v/v) acetic acid in acetonitrile and 0.1% (v/v) acetic acid in water. The analytes were identified using the multiple reaction monitoring (MRM) mode under negative electrospray ionization (ESI-) and quantified by isotope-labelled analogs. Para-nitrophenol (PNP), 3,5,6-tricholor-2-pyridinol (TCPY) and cis-dichlorovinyl-dimethylcyclopropane carboxylic acid (cis-DCCA) exhibited good linearities ranging from 0.2 to 100 μg/L, and 3-phenoxy benzoic acid (3-PBA), 4-fluoro-3-phenoxy benzoic acid (4F-3PBA), 2,4-dicholorphenoxyacetic acid (2,4-D), trans-dichlorovinyl-dimethylcyclopropane carboxylic acid (trans-DCCA) and 2,4,5-tricholorphenoxyacetic acid (2,4,5-T) showed linearity ranging from 0.1 to 100 μg/L with correlation coefficients all above 0.9993. Method detection limits (MDLs) and method quantification limits (MQLs) of targeted compounds were in the range of 0.02 to 0.07 μg/L and 0.08 to 0.2 μg/L, respectively. The spiked recoveries of target compounds at three levels of 0.5, 5 and 40 μg/L were 91.1% to 110.5%. The inter- and intra-day precisions of targeted analytes were 2.9% to 7.8% and 6.2% to 10%, respectively. This method was applied to the analysis of 214 human urine samples across China. The results showed that all the targeted analytes, except 2,4,5-T, were detected in human urine. The detection rates of TCPY, PNP, 3-PBA, 4F-3PBA, trans-DCCA, cis-DCCA, and 2,4-D were 98.1%, 99.1%, 94.4%, 2.80%, 99.1%, 63.1% and 94.4%, respectively. The median concentration of targeted analytes in a decreasing order were: 2.0 μg/L (TCPY), 1.8 μg/L (PNP), 0.99 μg/L (trans-DCCA), 0.81 μg/L (3-PBA), 0.44 μg/L (cis-DCCA), 0.35 μg/L (2,4-D) and below MDLs (4F-3PBA ). For the first time, we developed a method to extract and purify specific biomarkers of pesticides from human samples based on offline 96-well SPE. This method has the advantages of simple operation, high sensitivity, and high accuracy. Moreover, up to 96 human urine samples were analyzed in one batch. It is suitable for the determination of eight specific pesticides and their metabolites in large sample sizes.

Simultaneous determination of seven quaternary ammonium compounds in frozen food by ultra performance liquid chromatography-tandem mass spectrometry combined with modified QuEChERS method
LIU Bolin, ZHAO Ziwei, ZHAN Ziyue, DAI Yanyu, DING Gang, XIE Ji’an, XU Xiangchuan, KONG Hongtao
2023, 41 (3):  233-240.  DOI: 10.3724/SP.J.1123.2022.05008
Abstract ( 60 )   HTML ( 19 )   PDF (1003KB) ( 30 )  

Quaternary ammonium compounds (QACs) are a class of cationic surfactants that can be used as the main active ingredient of disinfectants. The increased use of QACs is concerning as exposure from inhalation or ingestion to these compounds that has been associated with adverse effects on the reproductive and respiratory systems. Humans are exposed to QACs primarily by food consumption and inhalation of air. QAC residues pose significant threats to public health. Given the importance of assessing potential residue levels for QACs in food, therefore, a method was developed for the simultaneous detection of six common QACs and one emerging QAC (Ephemora) in frozen food by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with the modified QuEChERS method. The main factors governing the response, recovery, and sensitivity of the method, including extraction solvents, types and dosages of adsorbents, apparatus conditions, and mobile phases, were optimized in the course of sample pretreatment and instrument analysis. QAC residues in frozen food were extracted using 20 mL methanol-water (90∶10, containing 0.5% formic acid) for 20 min by the vortex shock method. The mixture was ultrasonicated for 10 min and centrifuged at 10000 r/min for 10 min. A 1-mL aliquot of the supernatant was transferred to a new tube and purified using 100 mg of PSA adsorbents. After mixing and centrifugation at 10000 r/min for 5 min, the purified solution was analyzed. Target analytes were separated on an ACQUITY UPLC BEH C8 chromatographic column (50 mm×2.1 mm, 1.7 μm) at a column temperature of 40 ℃ and a flow rate of 0.3 mL/min. The injection volume was 1 μL. Gradient elution was performed using methanol and 5 mmol/L ammonium acetate solution as the mobile phases. Multiple reaction monitoring (MRM) was conducted in the positive electrospray ionization (ESI+) mode. The matrix-matched external standard method was used to quantify seven QACs. The optimized chromatography-based method completely separated the seven analytes. Good linear relationships were obtained for the seven QACs in the range of 0.1-100.0 ng/mL. The correlation coefficient (r2) ranged from 0.9971 to 0.9983. The limits of detection and limits of quantification ranged from 0.5 to 1.0 μg/kg and 1.5 to 3.0 μg/kg, respectively. Accuracy and precision were determined by spiking salmon and chicken samples with 3.0, 10.0, and 100.0 μg/kg of analytes, in compliance with the current legislation, with six replicates per determination. The average recoveries of the seven QACs ranged from 65.4% to 101%. The relative standard deviations (RSDs) were between 0.64% and 16.8%. Matrix effects of the analytes were between -27.5% and 33.4% in salmon and chicken samples after purifying using PSA. The developed method was applied to the determination of seven QACs in rural samples. QACs were detected in only one sample; the level did not exceed European Food Safety Authority specified residue limit standards. The detection method has high sensitivity, good selectivity and stability, and the results are accurate and reliable. It is suitable for the simultaneous rapid determination of seven QAC residues in frozen food. The results provide valuable information for future risk assessment studies targeting this class of compounds.

Simultaneous determination of 22 antibiotics in environmental water samples by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry
WANG Jin, YE Kaixiao, TIAN Yan, LIU Ke, LIANG Liuling, LI Qingqian, HUANG Ning, WANG Xinting
2023, 41 (3):  241-249.  DOI: 10.3724/SP.J.1123.2022.06004
Abstract ( 81 )   HTML ( 14 )   PDF (2555KB) ( 42 )  
Supporting Information

The widespread and frequent use of antibiotics to treat diseases or encourage animal growth has resulted in their persistence and accumulation in water, soil, and sediments. As a typical emerging pollutant in the environment, antibiotics have become an important research focus in recent years. Antibiotics are commonly found at trace levels in water environments. Unfortunately, the determination of various types of antibiotics, all of which exhibit different physicochemical properties, remains a challenging endeavor. Thus, developing pretreatment and analytical techniques to achieve the rapid, sensitive, and accurate analysis of these emerging contaminants in various water samples is an essential undertaking.
In this paper, a solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method for the simultaneous determination of 22 antibiotics including 4 penicillins, 12 quinolones and 6 macrolides in environmental water samples was developed. Based on the characteristics of the screened antibiotics and sample matrix, the pretreatment method was optimized, focusing on the SPE column, pH of the water sample, and amount of ethylene diamine tetra-acetic acid disodium (Na2EDTA) added to the water sample. Prior to extraction, a 200 mL water sample was added with 0.5 g of Na2EDTA and pH-adjusted to 3 using sulfuric acid or sodium hydroxide solution. Water sample enrichment and purification were achieved using an HLB column. HPLC separation was carried out on a C18 column (100 mm×2.1 mm, 3.5 μm) via gradient elution with a mobile phase composed of acetonitrile and 0.15% (v/v) formic acid aqueous solution. Qualitative and quantitative analyses were performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode using an electrospray ionization source. The results showed correlation coefficients greater than 0.995, indicating good linear relationships. The method detection limits (MDLs) and limits of quantification (LOQs) were in the ranges of 2.3-10.7 ng/L and 9.2-42.8 ng/L, respectively. The recoveries of target compounds in surface water at three spiked levels ranged from 61.2% to 157%, with relative standard deviations (RSDs) of 1.0%-21.9%. The recoveries of target compounds in wastewater at three spiked levels were 50.1%-129%, with RSDs of 1.2%-16.9%. The method was successfully applied to the simultaneous determination of antibiotics in reservoir water, surface water, sewage treatment plant outfall, and livestock wastewater. Most of the antibiotics were detected in watershed and livestock wastewater. Lincomycin was detected in 10 surface water samples, with a detection frequency of 90%, and ofloxacin showed the highest contents (127 ng/L) in livestock wastewater. Therefore, the present method exhibits excellent performance in terms of MDLs and recoveries compared with previously reported methods. The developed method presents the advantages of small water sample volumes, wide applicability, and fast analysis times; thus, it can be considered a rapid, efficient, and sensitive analytical method with excellent potential for monitoring emergency environmental pollution. The method could also provide a reliable reference for formulating antibiotic residue standards. The results provide strong support for and an improved understanding of the environmental occurrence, treatment, and control of emerging pollutants.

Determination of new glucocorticoid called clobetasol acetate in cosmetics by ultra performance liquid chromatography-tandem mass spectrometry
YANG Piaopiao, HUANG Wei, LI Lixia, LIU Hong
2023, 41 (3):  250-256.  DOI: 10.3724/SP.J.1123.2022.06010
Abstract ( 51 )   HTML ( 10 )   PDF (773KB) ( 24 )  

At present, new prohibited substances are becoming more common illegal additions in cosmetics. Clobetasol acetate is a new glucocorticoid, which is not covered in the current national standards and is a homologue of clobetasol propionate. A method was established for the determination of clobetasol acetate as a new glucocorticoid (GC) in cosmetics by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Five common cosmetic matrices were suitable for this new method: creams, gels, clay masks, masks and lotions. Four pretreatment methods were compared: direct extraction by acetonitrile, PRiME pass-through column purification, solid-phase extraction (SPE) purification, and QuEChERS purification. Further, the effects of different extraction efficiencies of the target compound, such as extraction solvents and extraction time, were investigated. The MS parameters, such as ion mode, cone voltage and collision energy of ion pairs of the target compound, were optimized. The chromatographic separation conditions and response intensities of the target compound in different mobile phases were compared. Based on the experimental results, the optimal extraction method was determined to be direct extraction, wherein the samples were vortex dispersed with acetonitrile, ultrasonic extraction over 30 min and filtered by a 0.22 μm organic millipore filter, and then the samples were detected by UPLC-MS/MS. The concentrated extracts were separated on a Waters CORTECS C18 column (150 mm×2.1 mm, 2.7 μm), where the water and acetonitrile were used as the mobile phases for gradient elution. The target compound was detected with the multiple reaction monitoring (MRM) mode under electrospray ionization and positive ion scanning (ESI+). Quantitative analysis was performed by matrix matching standard curve. Under the optimum conditions, the target compound had good linear fitting in the range of 0.9-37 μg/L. The linear correlation coefficient (R2) was greater than 0.99, the limit of quantification (LOQ) of the method was 0.09 μg/g and the limit of detection (LOD) was 0.03 μg/g for these five different cosmetic matrices. The recovery test was conducted under three spiked levels: 1, 2 and 10 times of LOQ. The recoveries of the tested substance were between 83.2% and 103.2% in these five cosmetic matrices, and the relative standard deviations (RSDs, n=6) were between 1.4% and 5.6%. This method was used to screen cosmetic samples of different matrix types, and a total of five positive samples were found, in which the content range of clobetasol acetate was from 1.1 to 48.1 μg/g. In conclusion, the method is simple, sensitive and reliable, and is suitable for high-throughput qualitative and quantitative screening, and the analysis of cosmetics with different matrix types. Moreover, the method provides crucial technical support and a theoretical basis for the establishment of feasible detection standards for clobetasol acetate in China, as well as for the control of the compound in cosmetics. This method has important practical significance to implement management measures of illegal additions in cosmetics.

Simultaneous determination of five lignans from Schisandra chinensis by matrix solid-phase dispersion extraction-high performance liquid chromatography
DU Xinxin, WANG Yinpeng, XIAO Wei, ZHU Jingbo
2023, 41 (3):  257-264.  DOI: 10.3724/SP.J.1123.2022.05012
Abstract ( 36 )   HTML ( 12 )   PDF (2074KB) ( 8 )  

The kidney-shaped, red-colord fruit from the plant, Schisandra chinensis (Turcz.) Baill, which belongs to the Schisandraceae family, is among the most popular remedies used in traditional Chinese medicine. The English name of the plant is “Chinese magnolia vine”. It has been used in Asia since ancient times to treat a variety of ailments, including chronic cough and dyspnea, frequent urination, diarrhea, and diabetes. This is because of the wide range of bioactive constituents, such as lignans, essential oils, triterpenoids, organic acids, polysaccharides, and sterols. In some cases, these constituents affects the pharmacological efficacy of the plant. Lignans with a dibenzocyclooctadiene-type skeleton are considered to be the major constituents and main bioactive ingredients of Schisandra chinensis. However, because of the complex composition of Schisandra chinensis, the extraction yields of lignans are low. Thus, it is particularly important to study pretreatment methods used during sample preparation for the quality control of traditional Chinese medicine. Matrix solid-phase dispersion extraction (MSPD) is a comprehensive process involving destruction, extraction, fractionation, and purification. The MSPD method is simple, it requires only a small number of samples and solvents, it does not require any special experimental equipments or instruments, and it can be used to prepare liquid, viscous, semi-solid, solid samples.

In this study, a method combining matrix solid-phase dispersion extraction with high performance liquid chromatography (MSPD-HPLC) was established for the simultaneous determination of five lignans (schisandrol A, schisandrol B, deoxyschizandrin, schizandrin B, and schizandrin C) in Schisandra chinensis. The target compounds were separated on a C18 column with a gradient elution of 0.1% (v/v) formic acid aqueous solution and acetonitrile as the mobile phases, and detection was performed at a wavelength of 250 nm. First, the effects of 12 adsorbents, including silica gel, acidic alumina, neutral alumina, alkaline alumina, Florisil, Diol, XAmide, Xion, and the inverse adsorbents, C18, C18-ME, C18-G1, and C18-HC, on the extraction yields of lignans were investigated. Second, effects of the mass of the adsorbent, the type of eluent, and volume of eluent on the extraction yields of lignans were investigated. Xion was chosen as an adsorbent for MSPD-HPLC analysis of lignans from Schisandra chinensis. Optimization of the extraction parameters showed that the MSPD method had a high lignan extraction yield with Schisandra chinensis powder (0.25 g) as a fixed value, Xion as the adsorbent (0.75 g), and methanol as the elution solvent (15 mL). Analytical methods were developed for five lignans from Schisandra chinensis and these methods showed good linearity (correlation coefficients (R2)≥ 0.9999) for each target analyte. The limits of detection and quantification ranged from 0.0089 to 0.0294 μg/mL and 0.0267 to 0.0882 μg/mL, respectively. Lignans were tested at low, medium, and high levels. The average recovery rates were 92.2% to 111.2%, and the relative standard deviations were 0.23% to 3.54%. Both intra-day and inter-day precisions were less than 3.6%. Compared with hot reflux extraction and ultrasonic extraction methods, MSPD has the advantages of combined extraction and purification, being less time-consuming, and requiring lower solvent volumes. Finally, the optimized method was successfully applied to analyze five lignans from Schisandra chinensis samples from 17 cultivation areas.

Determination of 15 carbonyl compounds in soil using improved solid phase extraction-high performance liquid chromatography
XUE Kunpeng, YU Lingyu, REN Xingfa, TU Bingfang, CHEN Chao, XU Ting, HE Huan, HU Shuai
2023, 41 (3):  265-273.  DOI: 10.3724/SP.J.1123.2022.05021
Abstract ( 56 )   HTML ( 7 )   PDF (5174KB) ( 33 )  

An improved solid phase extraction (SPE)-high performance liquid chromatography method was established to determine 15 carbonyl compounds, namely, formaldehyde (FOR), acetaldehyde (ACETA), acrolein (ACR), acetone (ACETO), propionaldehyde (PRO), crotonaldehyde (CRO), butyraldehyde (BUT), benzaldehyde (BEN), isovaleraldehyde (ISO), n-valeraldehyde (VAL), o-methylbenzaldehyde (o-TOL), m-methylbenzaldehyde (m-TOL), p-methylbenzaldehyde (p-TOL), n-hexanal (HEX), and 2,5-dimethylbenzaldehyde (DIM), in soil. The soil was ultrasonically extracted with acetonitrile, and the extracted samples were derivatized with 2,4-dinitrophenylhydrazine (2,4-DNPH) to generate stable hydrazone compounds. The derivatized solutions were cleaned using an SPE cartridge (Welchrom® BRP) packed with N-vinylpyrrolidone/divinylbenzene copolymer. Separation was performed on an Ultimate® XB-C18 column (250 mm×4.6 mm, 5 μm), isocratic elution was performed with acetonitrile-water (65∶35, v/v) as the mobile phase, and detection was performed at a wavelength of 360 nm. The 15 carbonyl compounds in the soil were then quantified using an external standard method. The proposed method improves the sample processing method described in the environmental standard HJ 997-2018: Soil and sediment-Determination of carbonyl compounds-High performance liquid chromatography. A series of experiments revealed the following optimal conditions for soil extraction: acetonitrile as the extraction solvent, extraction temperature of 30 ℃, and extraction time of 10 min. The results showed that the purification effect of the BRP cartridge was significantly better than that of the conventional silica-based C18 cartridge. The 15 carbonyl compounds showed good linearities, and all correlation coefficients were above 0.996. The recoveries ranged from 84.6% to 115.9%, the relative standard deviations (RSDs) ranged from 0.2% to 5.1%, and the detection limits were 0.02-0.06 mg/L. The method is simple, sensitive, and suitable for the accurate quantitative analysis of the 15 carbonyl compounds in soil specified in HJ 997-2018. Thus, the improved method provides reliable technical support for studying the residual status and environmental behavior of carbonyl compounds in soil.

Technical Notes
Determination of 14 paralytic shellfish toxins in plasma and urine by ultra-high performance liquid chromatography-tandem mass spectrometry
LIN Qiang, YANG Chao, LI Meili, WANG Jia, HOU Hanran, SHAO Bing, NIU Yumin
2023, 41 (3):  274-280.  DOI: 10.3724/SP.J.1123.2022.05030
Abstract ( 48 )   HTML ( 11 )   PDF (1951KB) ( 26 )  

The detection of paralytic shellfish toxins in human biological matrices is important for the diagnosis and treatment of food poisoning caused by them. An ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was established for the determination of 14 paralytic shellfish toxins in plasma and urine. The effect of solid phase extraction (SPE) cartridges was also investigated and the pretreatment and chromatographic conditions were optimized. Under these optimal conditions, 0.2 mL water, 0.4 mL methanol, and 0.6 mL acetonitrile were successively added to plasma and urine samples for extraction. The supernatants from plasma extraction were subjected to an UHPLC-MS/MS analysis, whereas the supernatants from urine extraction were further purified using polyamide (PA) SPE cartridges and then analyzed by UHPLC-MS/MS. Chromatographic separation was conducted on a Poroshell 120 HILIC-Z column (100 mm×2.1 mm, 2.7 μm) with a flow rate of 0.5 mL/min. The mobile phase was 0.1% (v/v) formic acid aqueous solution containing 5 mmoL/L ammonium formate and acetonitrile containing 0.1% (v/v) formic acid. The analytes were detected in the multiple reaction monitoring (MRM) mode after being ionized by an electrospray ion (ESI) in positive and negative modes. Quantitation of the target compounds was performed using the external standard method. Under the optimal conditions, the method showed good linearity in the range of 0.24-84.06 μg/L, with correlation coefficients greater than 0.995. The limits of quantification (LOQs) for the plasma and urine samples were 1.68-12.04 ng/mL and 4.80-34.4 ng/mL, respectively. The average recoveries for all the compounds were 70.4%-123.4% at spiked levels of 1, 2, and 10 times the LOQs, the intra-day precisions were 2.3%-19.1% and the inter-day precisions were 5.0%-16.0%. The established method was used to determine the target compounds in the plasma and urine from mice intraperitoneally injected with 14 shellfish toxins. All 14 toxins were detected in the 20 urine and 20 plasma samples, with contents of 19.40-55.60 μg/L and 8.75-13.86 μg/L, respectively. The method is simple, sensitive, and only requires a small amount of sample. Therefore, it is highly suitable for the rapid detection of paralytic shellfish toxins in plasma and urine.

Trapping array-based preparative two-dimensional liquid chromatography for the purification of four components in tobacco leaves
SHA Yunfei, XIONG Junwei, ZHAI Yulin, WANG Baolei, ZHONG Zhihua, FEI Ting, LI Duxin, WU Da
2023, 41 (3):  281-286.  DOI: 10.3724/SP.J.1123.2022.08021
Abstract ( 32 )   HTML ( 5 )   PDF (1009KB) ( 10 )  

Two-dimensional liquid chromatography (2D-LC) has gained increased attention because of its high peak capacity for separating complex samples. However, preparative 2D-LC aimed at isolating compounds is significantly different compared with one-dimensional liquid chromatography (1D-LC) in terms of method development and system configuration; thus, it is less developed than its analytical counterpart. The use of 2D-LC in large-scale product preparation has rarely been reported. Hence, a preparative 2D-LC system was developed in this study. The system was composed of one set of preparative LC modules as a separation system, with a dilution pump, switch valves, and trap column array as the interface, to enable the simultaneous isolation of several compounds. Tobacco was used as a sample, and the developed system was applied to isolate nicotine, chlorogenic acid, rutin, and solanesol. The chromatographic conditions were developed by investigating the trapping efficiency of different types of trap column packings, and chromatographic behaviors under different overload conditions. The four compounds were isolated in one 2D-LC run with high purity. The developed system features low cost because it employs medium-pressure isolation, excellent automation owing to its use of an online column switch, high stability, and capability for large-scale production. The isolation of chemicals from tobacco leaves as pharmaceutical raw materials could aid in the development of the tobacco industry and promote the local agricultural economy.