Phase Elution Research Articles

Influence of traditional Chinese medicines on the in vivo metabolism of lopinavir/ritonavir based on UHPLC-MS/MS analysis

A fast, reliable, and cost-effective liquid chromatography-tandem mass spectrometry method was established to determine the effects of the traditional Chinese medicine employed to treat coronavirus disease 2019, namely, Lianhua Qingwen granules, Huoxiang Zhengqi capsules, Jinhua Qinggan granules, Shufeng Jiedu capsules, and Angong Niuhuang pills, on the pharmacokinetics of lopinavir/ritonavir in rats. Blood samples were prepared using the protein precipitation method and atazanavir was selected as the internal standard (IS). Separation was performed on an Agilent ZORBAX eclipse plus C18 (2.1 mm × 50 mm, 1.8 μm) column using acetonitrile and water containing 0.1% formic acid as the mobile phase for gradient elution. The flow rate was 0.4 mL/min and the injection volume was 2 μL. Agilent Jet Stream electrospray ionization was used for mass spectrometry detection under positive ion multiple reaction monitoring mode at a transition of m/z 629.3→447.3 for lopinavir, m/z 721.3→296.1 for ritonavir, and m/z 705.4→168.1 for the IS. The method showed good linearity in the concentration range of 25–2500 ng/mL (r=0.9981) for lopinavir and 5–500 ng/mL (r=0.9984) for ritonavir. The intra-day and inter-day precision and accuracy were both within ±15%. Items, such as dilution reliability and residual effect, were also within the acceptable limits. The method was used to determine the effects of five types of traditional Chinese medicines on the pharmacokinetics of lopinavir/ritonavir in rats. The pharmacokinetic results showed that the half-life of ritonavir in the groups administered Lianhua Qingwen granules and Huoxiang Zhengqi capsules combined with lopinavir/ritonavir was prolonged by approximately 1.5- to 2-fold relative to that in the control group. Similarly, the pharmacokinetic parameters of lopinavir were altered. Overall, the results of this study offer important theoretical parameters for the effective clinical use of five types of traditional Chinese medicines combined with lopinavir/ritonavir to reduce the occurrence of clinical adverse reactions.

Optimized High-Performance Liquid Chromatography Method for Determining Nine Cytokinins, Indole-3-acetic Acid and Abscisic Acid

Liquid-liquid extraction and solid phase extraction followed by high-performance liquid chromatography (HPLC) connected with ultraviolet (UV) detection were used for the determination of phytohormones. The parameters influencing the performance of the HPLC-UV method, including composition of the mobile phase for gradient elution, column temperature, flow rate, and detection wavelength, were optimized. This method can simultaneously determine 11 phytohormones, including nine cytokinins, indole-3-acetic acid, and abscisic acid. The limit of detection of this method is 0.22 to 1.1 µg L−1, and the coefficient factors of linear regression are >0.998. The recoveries of the target phytohormones ranged between 62.1~109.4%, and the relative standard deviations were <10%. This method is suitable for determining phytohormones, especially cytokinins, in young panicles, roots, and xylem sap of rice plants.

Screening of quantitative preparation quality markers of Yulian Decoction

On the basis of the qualitative preparation quality markers of Yulian Decoction, we screened out the quantitative markers and explored a general strategy for analyzing the component migration in Chinese herbal pieces, preparations, and plasma. A method capable of simultaneously determining 28 chemical components in Yulian Decoction was established based on HPLC-MS/MS. This method was used to determine the migrated components in herbal pieces-lyophilized powder preparations-rat plasma after administration of Yulian Decoction. Liquid chromatography was performed under the following conditions: C_(18)-reversed phase chromatographic column(2.1 mm × 100 mm, 1.8 μm); acetonitrile-water(containing 0.1% formic acid) as the mobile phase for gradient elution; the flow rate of 0.2 mL·min~(-1). Electrospray ionization source was adopted for mass spectrometry detection, in which positive and negative ion modes and multiple reaction monitoring were applied. Confirmed by the methodological investigation in linear range, recovery(95.48%-103.4%), precision(RSD, 0.45%-3.8%), stability, and repeatability(RSD, 5.6%-14%), the established method was suitable for the detection and quantification of the components in Yulian Decoction. The results showed that in the lyophilized powder of Yulian Decoction, berberine was greater than 5% in mass fraction, magnoflorine, epiberberine, coptisine, palmatine, and limonin in the range of 1%-5%, and dehydroevodiamine, evodiamine, rutaecarpine, costunolide, and dehydrocostus lactone in the range of 0.002%-1%. Of the 28 components detected in pieces, 27 were found to migrate to the lyophilized powder, and 11 were detected in rat plasma. Fifteen components were preliminarily determined as quantitative preparation quality markers for Yulian Decoction, including berberine, epiberberine, coptisine, palmatine, evodiamine, rutaecarpine, limonin, costunolide, dehydrocostus lactone, magnoflorine, jatrorrhizine, columbamine, groenlandicine, chlorogenic acid, and neochlorogenic acid. In conclusion, the HPLC-MS/MS general strategy was established for analyzing the migration of multiple components in Chinese herbal pieces, preparations, and plasma, which can provide the basis for the screening of quantitative preparation quality markers and multi-index quality control of Yulian Decoction.

Quality Assessment of Insamyangpye Decoction by Liquid Chromatography Tandem Mass Spectrometry Multiple Reaction Monitoring

Insamyangpye decoction (ISYPD) is an oriental herbal prescription used in Korea to treat lung-related diseases such as chronic obstructive pulmonary disease. ISYPD is a complex prescription consisting of 13 herbal medicines, and ISYPD sample was obtained by adding 50 L of distilled water to a mixture (5 kg) of 13 herbal medicines, extracting at 100 °C for 2 h using an electric extractor, and freeze-drying. In this study, an accurate and sensitive liquid chromatography tandem mass spectrometry (LC–MS/MS) method based on multiple reaction monitoring (MRM) was developed and verified for quality assessment of ISYPD using 10 marker components: mulberroside A (1), amygdalin (2), liquiritin apioside (3), naringin (4), poncirin (5), platycodin D (6), ginsenoside Rb1 (7), glycyrrhizin (8), saikosaponin A (9), and schizandrin (10). These marker compounds were separated using an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) maintained at 30 °C with a mobile phase elution gradient of acetonitrile in distilled water, both containing 0.1% (v/v) trifluoroacetic acid. Marker components were quantified using the LC–MS/MS MRM method developed and validated, and found at 0.09–7.47 mg/g.

Chemome profiling of Pien-Tze-Huang by online pressurized liquid extraction-ultra-high performance liquid chromatography-ion trap-time-of-flight mass spectrometry

片仔癀(Pien-Tze-Huang)是由三七、牛黄、蛇胆、麝香等名贵中药经加工精制而成的中药制剂。片仔癀中的三七皂苷、胆汁酸以及麝香酮等主要化学成分已被深入研究,然而其全方化学成分组成尚未被整体阐明。该文建立了在线加压溶剂提取-超高效液相色谱-离子阱-飞行时间质谱(online PLE-UHPLC-IT-TOF-MS)法,快速、直接分析片仔癀化学成分组。将少量片仔癀粉末(0.3 mg)均匀地平铺于预柱芯尾端,之后用正相硅胶填充预柱芯,滤膜密封后构成提取池。提取池装入预柱套后置于70 ℃的柱温箱内,连接于UHPLC-IT-TOF-MS分析系统。通过引入一个二位六通电子阀,将整个分析过程自动在提取相和洗脱相间切换。提取相用时3 min,以0.1%(v/v)甲酸水为提取溶剂,流速为0.2 mL/min;洗脱相以0.1%(v/v)甲酸水和乙腈为流动相进行梯度洗脱,IT-TOF-MS检测。通过与对照品、相关文献和自建中药数据库对照,并总结相关质谱裂解规律,从片仔癀中共检测到73个化学成分,初步鉴定并归属了其中71个,36个来源于三七,15个来源于蛇胆,9个来源于牛黄,11个可能来源于牛黄与蛇胆,另有2个结构无法确定。该研究深入解析了片仔癀的化学成分组,为其质量分析提供了丰富的信息。同时,该文构建的online PLE-UHPLC-IT-TOF-MS分析系统为中药复杂体系快速、直接分析提供了可靠的工具。

Simultaneous determination of multiple bioactive constituents in Abelmoschi Corolla by UFLC-QTRAP-MS/MS

A comprehensive analytical method based on ultra-fast liquid chromatography coupled with triple quadrupole/linear ion trap tandem mass spectrometry(UFLC-QTRAP-MS/MS) was established for simultaneous determination of the content of 38 active components in Abelmoschi Corolla, including flavonoids, organic acids, nucleosides and amino acids, so as to investigate the effects of different harvesting and processing methods on multi-active components in Abelmoschi Corolla. The chromatographic separation was performed on a XBridg®C_(18) column(4.6 mm×100 mm, 3.5 μm) with(0.1% formic acid water) methanol-acetonitrile(1∶1) as the mobile phase for gradient elution at 30 ℃. The flow rate was 0.5 mL·min~(-1). The components were detected in a multiple-reaction monitoring(MRM) mode. The gray relational analysis(GRA) was used to comprehensively evaluate the multiple active components of Abelmoschi Corolla at different harvesting times and drying temperatures. The results showed that 38 components had a good linearity with correlation coefficients all above 0.999 0. The method featured a good precision, repeatability and stability with the relative stan-dard deviations(RSDs) of less than 5.0%. Recoveries ranged from 98.06% to 104.4% with RSD between 0.22% and 4.9%. The results of GRA indicated that a better quality in the samples collected on September 9 th. Samples dried at 90 ℃ had a better quality. The established method is accurate and reliable, and can be used to assess the internal quality of Abelmoschi Corolla. This study can provide basic materials for determining appropriate harvesting time and processing method of Abelmoschi Corolla.

A UPLC-MS/MS method for simultaneous determination of nine antiepileptic drugs in human plasma and its application in TDM.

With the purpose of carrying out therapeutic drug monitoring (TDM) of nine antiepileptic drugs simultaneously in the clinic, a UPLC-MS/MS assay method was developed and validated. Separation of antiepileptic drugs and internal standard (naproxen and diazepam) was performed on an Agilent Eclipse XDB-C18 column (50.0×2.1mm, 1.7μm) using water and acetonitrile as mobile phase for gradient elution. Polarity switch ionization mode (positive-negative-positive) was performed in a total run time of 3.0min. The method validation was conducted based on bioanalytical method validation guidance, including specificity, calibration curve, precision, accuracy, recovery, matrix effect, stability and dilution integrity, and all of the results satisfied the requirements. Consequently, the proposed method was applied to the TDM of nine antiepileptic drugs and was proved to be sensitive, reliable and specific to determine antiepileptic drugs in human plasma simultaneously. Meanwhile, the TDM results showed that the plasma drug concentration of many patients was not within the effective therapeutic range, especially those taking topiramate, oxcarbazepine and levetiracetam, which was of great guiding significance to rational drug use and timely adjustment of the treatment plan. Therefore, individualized therapy based on advanced analytical methods and TDM theory is of great practical significance.

A biorefinery approach to obtain docosahexaenoic acid and docosapentaenoic acid n-6 from Schizochytrium using high performance countercurrent chromatography

Schizochytrium has arisen as a valuable alternative to fish as a source of polyunsaturated fatty acids. In the present study, Schizochytrium limacinum CO3-H biomass was processed by direct transesterification affording a transesterified algal oil, from which docosahexaenoic acid (DHA) and docosapentaenoic acid n-6 (DPA n-6) ethyl esters were isolated using high performance countercurrent chromatography (HPCCC). A multiple sequential injection HPCCC separation method was developed combining two elution modes (reverse phase and extrusion). During the reverse phase elution, the lower phase of a biphasic solvent system (n-heptane:acetonitrile, ratio 5:5, v/v) was used as the mobile phase. During the initial reverse phase elution, the two target compounds were obtained, which was followed by the extrusion of the stationary phase by switching the pumping of the mobile phase to the stationary phase, while maintaining the column rotation. Once the column was refilled with stationary phase, a new hydrodynamic equilibrium condition was again reached for a new separation cycle. Ten consecutive sample injections (1000 mg of algal oil, each) were performed in this way leading to the separation of DHA ethyl ester (1, 797 mg, 99% purity) and DPA n-6 ethyl ester (2, 164 mg, 97% purity) with recoveries of 99% and 92%; respectively. The process throughput of algal oil was 1.149 g/h while the efficiency per gram of two target compounds was 0.110 g/h. Environmental risk and process evaluation factors were used for evaluation of the separation process. Overall, this separation strategy may represent a useful model for the co-production of DHA and DPA n-6 from microalgae oil under a biorefinery perspective because the potential co-production of other valuable compounds present in both the algal oil and biomass may contribute to enhancement of the economics of the approach.

Analysis of chemical constituents of Ginseng-Douchi compound fermentation products based on UPLC-Q-TOF-MS

In this experiment, ultra high performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS) was used to analyze and identify chemical constituents of Ginseng-Douchi(GD) compound fermentation, and explore the conversion rules of ginsenosides and soybean isoflavones after compound fermentation. Waters Acquity UPLC BEH C_(18) column(2.1 mm×100 mm, 1.7 μm) was adopted, with 0.1% formic acid aqueous solution(A)-0.1% formic acid acetonitrile solution(B) as mobile phase for gradient elution; electrospray ion source(ESI) was used to collect data in positive and negative ion modes; according to the exact mass number, the secondary spectrum comparison of the database and the existing literature reports, Peakview 2.0/masterview 1.0 software was used to determine the common ion structure formula. Finally, a total of 133 chemical constituents were analyzed and identified from the GD. Ginseng saponins and isoflavone glycosides were significantly converted after fermentation. Among them, peak areas of prototype ginsenosides Rk_3, Rh_1, Rh_2, Rh_3, daidzin, glycitin and genistin decreased significantly; whereas peak areas of se-condary ginsenoside Rb_1, Rb_2, Rk_1, glycitein, genistein and daidzein increased significantly. In this experiment, liquid-mass spectrometry technique was used to investigate the conversion of active ingredients of GD compound fermented products after co-fermentation, so as to provide a scientific basis for elucidating pharmacodynamics material basis and quality control.

Correlation study on non-volatile ingredients of Menthae Haplocalycis Herba formula granules and traditional herbal pieces by UPLC-MS/MS

To establish the method for determining non-volatile ingredients of neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, caffeic acid, isochlorogenic acid A, rosmarinic acid, ferulic acid, rutin, luteoloside, isoquercitrin, hesperidin, diosmin, diosmetin, luteolin, acacetin and linarin in Menthae Haplocalycis Herba formula granules and traditional herbal pieces by UPLC-MS/MS, and analyze the correlation of non-volatile ingredients in Menthae Haplocalycis Herba formula granules and traditional herbal pieces. Shim-pack GIST C_(18) column(2.1 mm×100 mm, 2 μm) was adopted with acetonitrile-0.1% formic acid aqueous solution as the mobile phase for gradient elution at the flow rate of 0.4 mL·min~(-1). The column temperature was set at 35 ℃. The quantitative analysis was performed using the electrospray ionization source and the multiple reaction monitoring. The linear relationship, resolution, repeatability and recovery of the 16 chemical components all met the requirements. The 16 non-volatile ingredients in traditional herbal pieces of Menthae Haplocalycis Herba could be tracked in formula granules. There were certain differences of the 16 chemical components among Menthae Haplocalycis Herba formula granules of different manufacturers and traditional herbal pieces of different producing areas. The UPLC-MS/MS method was simple, rapid and accurate, and could be used for the quality control of non-volatile ingredients in Menthae Haplocalycis Herba formula granules and traditional herbal pieces.

Determination of maytansinoids in Trewia nudiflora using QuEChERS extraction combined with HPLC

Three maytansinoids with strong cytotoxicities, dehydrotrewiasine, maytanbutine, and trewiasine, were isolated and identified from Trewia nudiflora, and maytanbutine was obtained from this plant for the first time. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction combined with high-performance liquid chromatography (HPLC) was established to determine the three maytansinoids in T. nudiflora. The effects of major factors on the extraction efficiency of the QuEChERS method were evaluated and the optimal conditions using acetonitrile-ethyl acetate (1:1, v/v) as the extraction solvent and PestiCarb as the clean-up sorbents were established. Compared with Soxhlet extraction (SE) and ultrasonic-assisted extraction (UAE), the QuEChERS method was easy-to-operate and afforded a cleaner extract. A phenomenex HyperClone BDS C18 column was used for HPLC analysis. Methanol-acetonitrile-water was chosen as mobile phase for gradient elution. Method validation showed that all analytes showed good linearity (r > 0.999) over the investigated ranges and satisfactory recoveries ranging from 95.0% to 105.0%. The developed QuEChERS–HPLC method was simple, efficient, and applicable to the determination of maytansinoids in T. nudiflora.

Development and validation of UPLC method for quantitative determination of major bovine milk oligosaccharides and their heat stability

Bovine milk oligosaccharides (BMOs) and human milk oligosaccharides (HMOs) have similar functions. In this investigation, a simple and rapid quantitative analysis method of UPLC for BMOs concentration was proposed, and the heat stability of BMOs was also revealed. BMOs were separated on an Acquity UPLC® Glycan BEH amide column (2.1 mm × 150 mm, 1.7 μm) using 100 mm ammonium formate (pH 4.5) and 100% acetonitrile as mobile phase for gradient elution at a flow rate of 0.45 mL min−1. The potential in quantification of BMOs were satisfactorily validated in terms of linearity (R2 ≥ 0.9992), repeatability and intermediate precision (RSD ≤ 4.46%), and spike recovery (≥90.27%). For all investigated oligosaccharides, LOD ranged from 1.97 to 9.38 μg L−1 and LOQ values ranged between 6.84 and 31.25 μg L−1. In addition, BMOs did not degrade after heating at 45–100 °C for 10–120 min.

Enantiomeric Separation of New Chiral Azole Compounds.

Twelve new azole compounds were synthesized through an ene reaction involving methylidene heterocycles and phenylmaleimide, producing four oxazoles, five thiazoles, and one pyridine derivative, and ethyl glyoxylate for an oxazole and a thiazole compound. The twelve azoles have a stereogenic center in their structure. Hence, a method to separate the enantiomeric pairs, must be provided if any further study of chemical and pharmacological importance of these compounds is to be accomplished. Six chiral stationary phases were assayed: four were based on macrocyclic glycopeptide selectors and two on linear carbohydrates, i.e., derivatized maltodextrin and amylose. The enantiomers of the entire set of new chiral azole compounds were separated using three different mobile phase elution modes: normal phase, polar organic, and reversed phase. The most effective chiral stationary phase was the MaltoShell column, which was able to separate ten of the twelve compounds in one elution mode or another. Structural similarities in the newly synthesized oxazoles provided some insights into possible chiral recognition mechanisms.

Quality evaluation of fried Glycyrrhizae Radix et Rhizoma pieces by HPLC fingerprint and multicomponent quantitative analysis

To establish the HPLC fingerprint and multi-component determination method of fried Glycyrrhizae Radix et Rhizoma pieces. HPLC analysis was performed on Thermo Acclaim ~(TM)120 C_(18) column(4.6 mm×250 mm, 5 μm). Acetonitrile-0.1% phosphoric acid aqueous solution was taken as the mobile phase for gradient elution. The flow rate was 1 mL·min~(-1),the column temperature was maintained at 30 ℃, and the detection wavelength was 237 nm and 360 nm. The similarity of 15 batches of fried Glycyrrhizae Radix et Rhizoma pieces was higher than 0.849, and 17 common peaks were identified. Liquiritin, isoliquiritin apioside, isoliquiritin, liquiritigenin, isoliquiritigenin and glycyrrhizic acid were identified; among them, the mass fractions of Liquiritin, isoliquiritin apioside, isoliquiritin, liquiritigenin, glycyrrhizic acid were were 0.519%-3.058%, 0.227%-0.389%, 0.070%-0.439%, 0.038%-0.173%, 1.381%-4.252%, respectively. According to the cluster analysis, the 15 batches of decoction pieces were classified into three categories; principal component analysis screened out four principal components, with the cumulative variance contribution rate of 86.630%, indicating that the principal components contained most information of original data. Partial least squares discriminant ana-lysis marked 6 differential components in the decoction pieces. The established fingerprint and multicomponent determination are stable and reliable, and can provide a reference for the quality control of Radix Glycyrrhizae Radix et Rhizomae and fried Glycyrrhizae Radix et Rhizoma pieces.

Determination of 12 acrylate compounds in plastic food contact materials via high performance liquid chromatography

A high performance liquid chromatography (HPLC) method was used to determine 12 acrylate compounds in plastic food contact materials. The plastic food contact material samples were extracted by ultrasonic with methanol. The mixed solution of water and acetonitrile was used as mobile phase for gradient elution. The samples were separated by ZORBAX SB-AQ column (250 mm×4.6 mm, 5 μm), and analyzed by diode array detector (DAD). The results showed that under the optimal chromatographic conditions, the 12 acrylate compounds had good linear relationships in the range of 0.01-10.0 mg/L, the correlation coefficient of the standard curves were higher than 0.999, and the detection limits (LODs) were 0.03-0.08 mg/kg. The recovery rate was between 85.4% and 110.7%, and the relative standard deviation was from 1.6% to 5.2%. The method was simple and accurate, and can be used for the analysis and detection of 12 acrylate compounds in plastic food contact materials.

Detection of alkanolamines in liquid cement grinding aids by HPLC coupled with evaporative light scattering detector.

Triethanolamine (TEA), triisopropanolamine (TIPA), diethanol isopropanolamine (DEIPA) are necessary cement additives, and knowing their contents is needed for quality control and also to understand final properties of the cement. Whether it is the production of grinding aids, technical research and development or application research all involve the detection of grinding aids. This work developed a simple analytical technique for the simultaneous analysis of these alkanolamines in liquid cement grinding aids using high-performance liquid chromatography (HPLC) combined with evaporative light scattering detection (ELSD). HPLC was conducted by an XBridge C18 column (with dimensions 4.6 × 250 mm and 5 µm particles) using methanol and 0.1% trichloroacetic acid as mobile elution phases. The ELSD sprayer and drift tube temperatures were 60 ºC and 90 ºC, respectively. HPLC-ELSD developed in this work demonstrated 1) high sensitivity with limits of detection for the three analytes are 0.15, 0.54, 1.04 µg/mL; 2) good linearity with correlation coefficients equal to 0.997–0.999 over the tested concentration range; 3) excellent repeatability with intra- and interday coefficient of variation (CV) below 2.71% and 4, satisfactory accuracy with recovery in the 95.5%–100.8% range. This novel method is a powerful, time- and costeffective tool for alkanolamine analyses and quality control.

Middle-up characterization of monoclonal antibodies by online reduction liquid chromatography-mass spectrometry

This study describes the fully automated middle-up characterization of monoclonal antibodies (mAbs) and next-generation variants by online reduction liquid chromatography-mass spectrometry (LC-MS). Proteins were trapped on-column and subjected to online desalting, denaturation and reduction prior to reversed phase elution of the created subunits in the MS. The evaluation of more than 20 different therapeutic proteins including full length mAbs (subclasses IgG1, IgG2 and IgG4), bispecific antibodies, antibody fragments, fusion proteins and antibody-drug conjugates (ADC) revealed that the online reduction method is as powerful as the widely applied offline sample preparation with dithiothreitol (DTT) as reducing agent and guanidine hydrochloride (Gnd.HCl) as denaturant and tackles some major disadvantages associated with the latter method, i.e. corrosion of stainless steel components, adduct formation impacting spectral quality and sample stability. The value of the online reduction LC-MS method is also enforced by its ability to reveal unstable antibody variants such as succinimide intermediates of asparagine deamidation and aspartic acid isomerization which are often lost when using the offline sample preparation method. The performance of the online reduction LC-MS set-up was verified and it was revealed that the method is precise with RSD values below 0.25% and 3.0% for retention time and area, respectively. Carry-over is within acceptable limits (< 0.5%) and the reducing buffer is stable up to 24 hours.

Sulfamethizole functionalized graphene oxide for in-vitro separation and determination lead in blood serum of battery manufactories workers by syringe filter-dispersive- micro solid phase extraction

The toxic effect of lead (Pb) causes to anemia and iron deficiency in human body. So, the lead determination in blood/serum samples is very important. In this study, a novel adsorbent based on sulfamethizole functionalized on nanographene oxide (C3H10N4O2S2-NGO; SM-NGO) was used for extraction of Pb(II) from human blood, serum and plasma samples in battery manufactories workers by SF-D-µ-SPE. By procedure, 25 mg of SM-NGO mixed with 10 mL of human blood/serum or plasma samples and aspirated by 10 mL of syringe tube. After sonication of samples for 5 min, the Pb ions adsorbed based on sulfur of SM-NGO adsorbent at pH=6 and the solid phase separated by syringe coupled to Millex-FG hydrophobic PTFE membrane (0.2 µm). Then, the lead ions were back-extracted from SM-NGO/PTFE by elution phase with 0.5 mL of nitric acid solution (0.5 M). Finally, the concentrations of Pb(II) ions were determined by AT-FAAS.

Analysis of Aspirin, Prasugrel and Clopidogrel in Counterfeit Pharmaceutical and Herbal Products: Plackett-Burman Screening and Box-Behnken Optimization.

An isocratic reversed-phase high-performance liquid chromatographic method has been developed and validated for the simultaneous determination of aspirin, prasugrel HCl and clopidogrel bisulfate in the presence of clopidogrel-related compound (impurity-A) in focus on counterfeit. This method was used to determine counterfeited antiplatelet drugs in two substandard Indian pharmaceutical products sold on the market in Yemen and two traditional herbal medicines sold on the market in China. Thin layer chromatography and mass spectrometry of counterfeit herbal medicines have additionally been carried out to verify the identification of adulterants. Chromatographic separation was performed on Inertsil ® ODS-3 C18 (4.6 × 250mm, 5μm) with isocratic mobile phase elution containing a mixture of acetonitrile: (25mM) potassium dihydrogen phosphate buffer, pH2.7 adjusted with 0.1M o-phosphoric acid (79: 21, v/v), at a flow rate of 1mL/min and UV detection at 220nm. Designs of experiment methodology, Plackett-Burman and Box-Behnken designs were used for the screening and optimization of the mobile phase composition. The method validation was also performed in accordance with the International Council on Harmonization (ICH) guidelines. The method developed for routine analysis was found to be sensitive, simple, accurate and highly robust. The results were statistically compared to reference methods using Student's t-test and variance ratio F-test at P<0.05.

A rapid liquid chromatography-electrospray ionization-ion mobility spectrometry method for monitoring nine representative metabolites in the seedlings of cucumber and wheat.

A fast and convenient high-performance liquid chromatography-electrospray ionization-ion mobility spectrometry method was developed to determine nine representative metabolites in the seedlings of cucumber and wheat. The analytical conditions were obtained by optimizing the parameters of high-performance liquid chromatography and ion mobility spectrometry. Briefly, acetonitrile-0.1% formic acid solution was selected as the mobile phase for gradient elution at a flow velocity of 0.4mL/min. Under negative electrospray ionization mode, spray voltage of ion mobility spectrometry was 4.5kV, and drift tube temperature was set at 90°C. The metabolites from seedling leaves were extracted using 80% acetonitrile as the solvent at 4°C for 12 h. Results showed that under soilless culture conditions, the contents of maltose, citric acid, and p-hydroxybenzoic acid in the seedlings of cucumber and wheat were reduced by low concentration of itaconic acid, succinic acid, and citric acid. Importantly, this analytical approach demonstrated high sensitivity, good linear response, and high selectivity. The lowest limit of detection was 0.004μg for p-hydroxybenzoic acid. Overall, this high-performance liquid chromatography-electrospray ionization-ion mobility spectrometry method is sensitive and efficient for rapid separation and identification of plant metabolites.