This paper reviews the capillary electrophoresis (CE) in 2018. The literatures searched from ISI Web of Science in 2018 (Jan. 1st to Dec. 31th) are classified and introduced based on life science, drugs analysis, chiral separation, medical and clinical tests, CE related instruments improvement, food safety tests and environmental monitoring. Eight conferences and the important reports are introduced briefly. The current domestic and foreign standards of CE method are complemented. In the end, the major domestic CE instruments are listed.
Human milk is the optimal food for infant nutrition and growth. Proteins are abundant and represent a key element in human milk. With recent developments in proteomics, more tools are available to explore human milk proteins. This article aims to review the recent investigations of human milk proteins using proteomic methodologies. This review focuses on using proteomics as a tool to study the components of human milk proteins; dynamics of human milk proteins during lactation; comparison of proteome from human milk and other source milk, phosphoprotein and glycoprotein analysis of human milk; endogenous peptides in human milk; and the human milk proteome and its correlation to curing of various diseases. Proteomics technology has enabled the study of human milk proteins in the era of micronutrient research, and the results of these studies will be helpful for further analysis of mother and infant health.
Liquid chromatography (LC) and mass spectrometry (MS)-based proteomics now allows very deep coverage of proteomes. Two-dimensional high performance liquid chromatography (2-D HPLC) is a useful tool for the proteome analysis of complex biosystem. However, it has drawback of a long running time, and it typically requires peptide amounts in the milligram range, and large volume of collected fractions. In this study, we introduce ultra-performance liquid chromatography (UPLC) and an eight-port rotor valve as a highly efficient and convenient method for a first-dimension separation and collection system. The combination of our UPLC-based fractionation using basic buffers with an online LC-MS/MS provided orthogonal peptide separation and demonstrated the powerful performance for protein identification. Upon applying the novel method to triplicate measurements of a human cell line, we observed excellent quantitative reproducibility between replicates (coefficient of determination R2>0.95) and more than 23.52% peptide identifications over the conventional StageTip approach. The fractionation method described here is flexible, straightforward, and robust, and it enables proteome analysis with minimal sample requirements.
With polyethylene glycol as a porogen, vinyltrimethoxysilane (VTMS) and tetramethoxysilane (TMOS) as silica precursors, a hybrid silica monolithic material was obtained under the catalysis of acetic acid and thermally decomposed urea. The silica monolithic material was ground by a ballmill, treated with tris(hydroxymethyl)aminomethane (Tris), then washed and dried to obtain silica particles with particle size~3 μm. The effects of different reaction conditions on the particle size, surface morphology and dispersibility of silica particles were investigated. When the volume ratio of TMOS to VTMS was 3:1, it was observed that silica particles with a pore diameter of 7.5 nm and a specific surface area of 245 m2/g were obtained. The resultant silica particles were modified by binding with chlorodimethyloctadecylsilane (C18) and by the thiol-ene click reaction to obtain a mixed-mode type stationary phase. The test results showed that the silica packing materials prepared in this work has certain applicability.
In this study, a solid-phase extraction-high performance liquid chromatography (SPE-HPLC) method was developed for the determination of Para Red, Orange Ⅱ sodium salt, Sudan Ⅰ, and Sudan Ⅱ in paprika powder based on a self-made porous aromatic framework-6 (PAF-6) solid-phase extraction cartridge. The major factors affecting the extraction efficiency and adsorption capacity of this solid-phase extraction were evaluated. Under optimized conditions, the limits of detection (LODs) and limits of quantification (LOQs) of the four target analytes ranged from 1.5 to 7.0 μg/L and 5.0 to 22.1 μg/L, respectively. The recoveries were in the range of 76.5-89.8%, and the relative standard deviation (RSD) was not more than 5.3% (n=6). Moreover, quantum chemistry calculations were performed to investigate the molecular interaction mechanism between the PAF-6 and target analytes. The results indicated that the target molecules could be stably adsorbed onto the PAF-6. The method is accurate, reliable, and sensitive, and can be successfully applied to detect the four azo dyes in paprika powder.
A method using mixed-mode ion exchange liquid chromatography-tandem mass spectrometry was developed for the determination of streptomycin, dihydrostreptomycin, spectinomycin, kanamycin and amikacin in honey. The honey samples were extracted with phosphate followed by clean-up with SupelMIP Aminoglycosides SPE cartridges. The separation was performed on an SIELC Obelisc R column (100 mm×2.1 mm, 5 μm) by the gradient elution program using 0.1%(v/v) formic acid aqueous solution and acetonitrile as the mobile phases, at a flow rate of 0.4 mL/min. Five aminoglycosides (AGs) were identified by the tandem mass spectrometer with an electrospray ionization source under the multiple reaction monitoring (MRM) mode. The quantification analysis was performed by the external standard method. The calibration curves showed good linearity in the range of 5-100 μg/L for streptomycin and dihydrostreptomycin, and 20-500 μg/L for spectinomycin, kanamycin and amikacin. The limits of quantification (LOQs) of the five drugs in honey were 5-20 μg/kg. The average recoveries of the five drugs from feeds spiked at LOQ, 2-fold LOQ and 5-fold LOQ levels were 75.1%-92.3%, and the relative standard deviations (RSDs) were 4.5%-10.7%. The method is simple, rapid, and sensitive, and is suitable for the simultaneous determination of the five aminoglycoside residues in honey.
A method for the simultaneous determination of ten lipophilic shellfish toxins was established based on graphene-based pipette tip solid-phase extraction (G-PT-SPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The factors influencing the extraction efficiency, including the types of extractants, the amount of graphene, the types and volumes of washing and eluent solvents, were optimized in detail. Under the optimal conditions, the calibration curves showed linear relationships between the LC peak areas of the selected ion-pairs and the mass concentrations of the ten lipophilic shellfish toxins with correlation coefficients >0.99. The limits of detection (LODs) and the limits of quantification (LOQs) of the method were 0.1-1.1 μg/kg and 0.3-3.2 μg/kg, respectively. The recoveries of the ten lipophilic shellfish toxins spiked in blank oyster at three levels ranged from 72.0% to 101.2% with relative standard deviations <15%. The method is sensitive, simple, and effective, and is suitable for the determination of the lipophilic shellfish toxins in shellfish products.
Yunnan Province has many wild edible fungi resources, and of these, endogenous nicotine has received extensive attention in recent years. In this study, wild edible fungus was used as the research object, and the QuEChERS method was improved, including optimization of solvent extraction and purification conditions and optimization of the chromatographic behavior of nicotine under different mobile phase conditions for ultra performance liquid chromatography (UPLC). Combined with triple quadrupole mass spectrometry, a high-efficiency, rapid, and sensitive method for the determination of nicotine in wild edible fungi was established. The results showed that an ammonia:acetonitrile (6:94, v/v) mixed solution can completely extract nicotine from wild edible fungi, and the extraction solution was purified by graphitized carbon black (GCB) and N-propylethylenediamine (PSA) mixed filler. Then, a 0.1% (volume percentage) ammonia solution and acetonitrile were used as the mobile phases. The nicotine peak obtained in the positive ion multiple reaction monitoring (MRM) mode had a better peak shape and better response. The linear relationship of nicotine mass concentration with peak area in the range of 0.05-50.0 μg/L was good. The correlation coefficient (r2) was 0.9999. The limit of quantification was 0.2 μg/kg, and the limit of detection was 0.05 μg/kg. The average recovery rates at three spiked concentrations were in the range of 86.34%-96.4%, and the relative standard deviations varied from 4.44% to 6.3%. The sensitivity and recovery of this method are consistent with the rapid determination of nicotine in the edible fungus industry.
A highly efficient and economic method for the simultaneous determination of six common antibiotics (two tetracyclines, two quinolones, and two sulfonamides) in chicken manure was developed by using solid-phase extraction and high performance liquid chromatography (SPE-HPLC). The samples were extracted by using a mixture of the EDTA-McIlvaine buffer and a mixed organic extractant (methanol-acetonitrile-acetone, 2:2:1, v/v/v), cleaned by a hydrophile-lipophile balance (HLB) cartridge, eluted by methanol-dichloromethane (7:3, v/v), and separated by HPLC with an acetonitrile-0.7% (v/v) H3PO4 aqueous solution as the mobile phase. The detection wavelength and temperature of the chromatographic column were 270 nm and 32℃, respectively. All antibiotics showed great linear relationships in the range of 0.5-100 mg/L; the correlation coefficients (r2) of the standard curves were between 0.9999 and 1; the recoveries of antibiotics were between 70.0% and 116.3%; and the relative standard deviations were between 1.2% and 16.6%. The limits of detection were 1.3-6.7 μg/kg; and the limits of quantity were 3.5-9.2 μg/kg. This method was used to detect antibiotics in chicken manure from a hennery in Fushun, Liaoning Province. The contents of norfloxacin and enrofloxacin (quinolones) were from not detected to 9.23 mg/kg and 1.57-7.69 mg/kg, respectively, that of sulfamethazine (sulfonamides) were 2.02-13.05 mg/kg, while sulfamethoxazole, oxytetracycline, and tetracycline were undetectable.
A method was developed for the determination of five categories of 40 antibiotics in surface water by using solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS). The water samples were enriched and cleaned-up by filtration and with SPE cartridges. All antibiotics were separated by gradient elution with the mobile phase of 0.2% (v/v) formic acid aqueous solution and acetonitrile, and then analyzed with an electrospray ionization source in the positive ion and multiple reaction monitoring (MRM) modes. The results showed that the 40 antibiotics achieved great linearity in the range of 1-200 μg/L, and the average recoveries ranged from 41.3% to 112.6%. Using the developed method, thirteen antibiotics were identified in surface water from Nanjing section of the Yangtze River. The total antibiotic contents in the real samples ranged from 13.4 ng/L to 780.5 ng/L. The established method is efficient, sensitive and reliable, and is suitable for the determination of different antibiotics in real water samples.
Beta-2-microglobulin (B2M) is an important material in dialysis-related amyloidosis research. Unfortunately, the quantitative detection of the B2M monomer is difficult during B2M production. In this study, we established a method for the detection of the B2M monomer and its dimer in solution via gel filtration chromatography. The B2M powder was dissolved in 0.01 mol/L phosphate-buffered solution (PBS, pH 7.2-7.4) with a final mass concentration of 0.5 g/L. The B2M sample was analyzed on a TSKgel SuperSW2000 column (30 cm×4.6 mm, 4 μm) by an Agilent 1200 Series HPLC using 0.01 mol/L PBS (pH 7.2-7.4) as the mobile phase at a flow rate of 0.5 mL/min. The temperature of the column was 25℃, and the detection wavelength was 280 nm. The purities of the B2M monomer and the B2M dimer were tested. A series of concentrations of B2M monomer solutions were prepared to create a standard working curve. The standard working curve of the B2M monomer had a good linear relationship (coefficient of correlation (r2) was 0.9948). The limit of quantitation for the B2M monomer in PBS was 0.08 g/L (S/N=10). The recoveries were 85.0%-96.7% with relative standard deviations of 1.7%-3.3% at spiked levels of 0.10-0.30 g/L. The quantification of the B2M monomer was undisturbed by the B2M dimer, which can form during the B2M purification process. This determination method is simple, stable, and reliable for the determination of the B2M monomer in B2M industrial production.
An analytical method was developed for the simultaneous determination of five cholesterol oxidation products (COPs) in marinated pig feet and hocks by gas chromatography-mass spectrometry (GC-MS). The five COPs were 7 β -hydroxycholesterol, cholesterol-5 α,6 α -epoxide, 3 β,5 α,6 β -trihydroxycholestane, 25-hydroxycholesterol and 7-ketocholesterol. The sample was extracted with methanol-chloroform (1:2, v/v) and purified by solid phase extraction. Subsequently, the sample was collected for derivatization by N,O-bis(trimethylsilyl)acetamide-trimethyl chlorosilane-1-trimethylsilyllimidazole (3:2:3, v/v/v) (Sylon BTZ). The column temperature was properly programmed, and the selected ion monitoring (SIM) mode was used for the determination of COPs. Under optimum conditions, the five COPs were well separated within 22 min with good separation. The linear range of the five COPs met the requirement of determination, and the average recoveries of the five COPs spiked in the pork samples at three levels were 61.16%-96.96% with relative standard deviations (RSDs) no more than 7.80% (n=3). The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.02-47.07 ng/g and 0.06-156.90 ng/g, respectively. This method has a wide line arrange and high sensitivity, and has been successfully applied to the analysis of COPs in actual samples.
A method to determine fatty alkyl dimethyl tertiary amines by gas chromatography (GC) was set up using HP-INNOWax capillary column, hydrogen flame ionization detector (FID) and temperature programming. The linearities were all excellent in the range of 0.005-1.0 g/L with the correlation coefficients being above 0.9996. The limits of detection (LODs, S/N=3) of the method were between 0.001 g/L and 0.002 g/L, and the limits of quantification (LOQs, S/N=10) were between 0.003 g/L and 0.005 g/L. The recoveries ranged between 90% and 130% with relative standard deviations of 1.3%-6.9% (n=6). The proposed method has the advantages of wide linear range, higher recovery, and selectivity, which was suitable for the quantitative analysis of fatty alkyl dimethyl tertiary amines and monitoring process control in industrial production. The method was faster and more accurate than titration, and also precluded the need for pre-column derivatization and determination by liquid chromatography-tandem mass spectrometry.
Silica particles having different sizes were synthesized by a modified Stöber method. The reaction temperature, stirring rate, and time conditions were optimized. Finally, 580 nm monodispersed silica particles were synthesized. Moreover, a novel zwitterionic stationary phase with strong hydrophilicity was prepared based on a "thiolene" click reaction between cysteine and the silica particles modified vinyl group (Cys-vinyltrichlorosilane (VTMS)-SiO2). A column packed with submicron cysteine-bonded silica was prepared by the slurry packing method. The hydrophilic mechanism was revealed by the separation of toluene, acrylamide, and thiourea using different ratios of acetonitrile. The effects of applied voltage, buffer concentration, and buffer pH on the separation ability of the capillary column packed with 580 nm Cys-VTMS-SiO2 were examined to achieve optimal results. In addition, the run-to-run and day-to-day reproducibilities in terms of retention time and peak area for the above mentioned compounds were both 2.0%. The good batch-to-batch reproducibility indicated that the preparation method was suitable for the fabricated column. The column used in the pressurized capillary electrochromatography (pCEC) system demonstrated efficient and fast separation of a mixture consisting of nucleosides, phenols, amines, and peptides after the optimization of the separation condition. The proposed method shows good potential for the separation of polar and hydrophilic compounds.
With the development of life science, nano liquid chromatography systems are being involved in various applications in the field of biochemical analysis. Being one of the key components in the system, the nano flow rate pump directly affected the accuracy and repeatability of the analysis. Based on two high precision direct-driven motors and a ten-port switch valve, a single stroke direct-driven ultrahigh pressure nano pump was developed. The results show that the accuracy of the flow rate and stability were better than 1% and 0.7%, respectively, at 500 nL/min. The maximum operating pressure was more than 100 MPa, and the gradient deviation was lower than 1%. The nano pump was used to construct a nano liquid chromatography-mass spectrometry system. A bovine serum albumin (BSA) digest (1 μg) was analyzed by the system, and a sequence coverage of 45% was achieved. Furthermore, 2809 proteins were identified from a 1.25 μg Hela cell digest. All these results demonstrated that the single stroke direct-driven ultrahigh pressure nano pump could be a useful tool in the biochemical analyses, especially for proteome research.
byDalian Institute of Chemical
Physics,CASNational Chromatographic R. and A.
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