A Comparison of Three Methods of Extraction for the Determination of Polyphenols and Organic Acids in Tobacco by UPLC–MS–MS

Matrix solid phase dispersion (MSPD), ultrasonic extraction followed by a solid phase extraction (USE–SPE) and reflux extraction (REFLUX) were studied for the analysis of polyphenols and organic acids in tobacco. The analysis was by ultra-high performance liquid chromatography tandem mass spectrometry (UPLC–MS–MS). The multi-mode support sorbent Zirconia/AA12S50 in MSPD is more suitable for the extraction of tobacco polyphenols than conventional silica or C18 silica. Although the matrix effect of USE–SPE is slightly stronger than MSPD and REFLUX for most target compounds, it gave higher extraction capacity, recoveries and sensitivity.     

Study on the Structures and Properties of Copper Removal Adsorbent Prepared from Sinter-free Pulverized Oyster Shell Materials

A hollow tubular copper removal adsorbent was prepared with oyster shell and cement as the main raw materials. The effects of different formulas, different initial copper concentrations and different pH values of samples on the copper removal efficiency were investigated to determine the optimal conditions for copper removal. The content of copper in the wastewater is determined by Atomic Absorption Spectrophotometer. The microstructure and elemental composition of the samples were characterized by scanning electron microscopy(SEM) and EDS. As a result, the formula with the content of cement to be 8 wt% and the oyster shell powder of 92 wt% is optimal. Under the condition of 30 ℃, when the pH value was 9.0, the Cu2+ adsorption capacity of the sample could reach 0.59 mg/g at 48 h. SEM analysis revealed that there are abundant pores in the sample, which is beneficial for Cu2+ absorption on the adsorbent.     

Determination of Pesticides Adsorbed on Arthropods and Gastropods by a Micro-QuEChERS Approach and GC–MS/MS

A miniaturized QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Save) approach combined with gas chromatography–tandem mass spectrometry (GC–MS/MS) has been developed for the simultaneous determination of nine pesticides (Cyflufenamide, Difenoconazole, Dimethomorph, Fluopicolide, Fluopyram, Metrafenone, Myclobutanil, Quinoxyfen, and Tebuconazole) in insects, snails, and spiders. In contrast to the original QuEChERS approach, only 500 mg of dried and homogenized sample matrix, mixed with 1.0 mL ethyl acetate and 250 mg MgSO₄:NaCl (4:1), is required for this novel “micro-QuEChERS” protocol. The organic phase was cleaned using dispersive solid-phase extraction (dSPE) with 75 mg MgSO₄:PSA sorbent (4:1). The method was validated according to SANCO/12571/2013 and applied to real samples (n = 7). Fluopicolide was the only detectable pesticide in real samples from vineyards. In two samples, the Fluopicolide levels were between the determined LOD and LOQ (0.15–1.00 mg kg^?1), and in one sample a concentration of 1.68 mg kg^?1 was detected.     

Determination and Pharmacokinetic Study of Methyl Nonyl Ketone in Rat Plasma by GC–MS

A rapid and sensitive method for determination of methyl nonyl ketone in rat plasma was developed based on GC–MS. The analyte and internal standard, propyl p-hydroxybenaoate, were extracted from plasma with methyl tert-butyl ether and then separated by an HP-5MS capillary analytical column (30 m × 0.25 mm, 0.25 µm) and determined by a quadrupole mass spectrometer detector operated under EI ionization and selected ion monitoring mode. Excellent linearity was found to be from 5.0 to 1,000 ng mL^?1 with a lower limit of quantitation of 5.0 ng mL^?1. The accuracy was between 96.0 and 106.3%, and the intra- and inter-day precision and accuracy values were found to be within the assay variability criteria limits according to the FDA guidelines. The developed method was successfully applied to the pharmacokinetic study of methyl nonyl ketone, a typical component in the traditional Chinese medicine Houttuynia cordata injection, in rats after a single oral dose of 100 mg kg^?1 and peritoneal injection dose of 5 mg kg^?1, respectively.     

A Study on the Simultaneous Determination of Copper and Tin in the Presence of Lead

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Development and Validation of a GC–MS Method for the Determination of Methyl and Ethyl Camphorsulfonates in Esomeprazole Magnesium

A rapid gas chromatography–mass spectrometry method for the identification and determination of two carcinogenic impurities viz. methyl camphorsulfonate (MCS) and ethyl camphorsulfonate (ECS) in esomeprazole magnesium (EOM) is developed for the first time. The factors affecting method development and the fragmentation patterns of MCS and ECS based on the mass spectral analysis are described. The limit of detection and limit of quantitation values for both compounds were established as 3 and 10 ppm, respectively with respect to 50 mg mL^?1 of EOM. The method is linear within the range of 10–120 ppm and found to be precise, accurate, specific and robust.     

Investigation of Matrix Effects on the Determination of Carbadox and Olaquindox in Feed by LC–MS/MS

A comprehensive survey of matrix effects on the LC–MS/MS analysis of the banned antibiotic growth promoters carbadox and olaquindox in feed was carried out. Various factors of sample preparation procedure and measurement were systematically investigated by pre- and post-extraction addition and postcolumn infusion experiments. In general, strong signal suppression up to 70 % for carbadox and up to 90 % for olaquindox was observed when using different extraction solvents and techniques as well as different chromatographic conditions. Reduction of matrix effects was achieved by SPE clean-up and dilution of sample extracts. Nevertheless, matrix effect profiles determined by postcolumn infusion revealed, that reduction of signal suppression at a respective retention time cannot guarantee improvement of the methods performance. If high variability of matrix effects is present along the chromatographic run, accuracy might decrease despite reduced signal suppression. Besides method parameters, different feedingstuffs were investigated and showed similar matrix effects.     

LC Determination of the Skin Exposure to Oxamyl on Greenhouse Workers and Comparison Between DAD and MS–MS Detection

An LC–DAD method was developed to determine residues of oxamyl on greenhouse workers’ skin. The wipe test was used to obtain samples from hands, forearms, neck and gloves of workers taking cactus cuttings 48 h after pesticide treatment. It was validated in a concentration range 50–5,000 ng mL^?1. The results on six workers and ten office employees indicated significant differences particularly in the hand samples. To avoid the overestimation owing to an interfering substance we proceeded to confirm these findings with LC–MS–MS, which found the pesticide only on the surface of the workers’ gloves, proving that there was indeed some UV interference.     

HPLC–MS/MS Analysis and Study on the Adsorption/Desorption Characteristics of Ginsenosides on Anion-Exchange Macroporous Resins

Chromatographia - Anion exchange resin is a modified version of polar/nonpolar macro porous resins with enhanced selectivity on compounds carrying negative charges. Although it is a promising...     

An SCF－MS－Xα Study of the Electronic Structures of Binuclear and Trinuclear Gold（Ⅰ） Compounds

ＡｎＳＣＦ－ＭＳ－ＸαＳｔｕｄｙｏｆｔｈｅＥｌｅｃｔｒｏｎｉｃＳｔｒｕｃｔｕｒｅｓｏｆＢｉｎｕｃｌｅａｒａｎｄＴｒｉｎｕｃｌｅａｒＧｏｌｄ（Ⅰ）ＣｏｍｐｏｕｎｄｓＧＵＯＣｈｕｎ－ｘｉａｏ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＪｉｌｉｎＵｎｉｖ...     

Comparison of LC–UV, LC–ELSD and LC–MS Methods for the Determination of Sesquiterpenoids in Various Species of Artemisia

Simple and specific analytical methods for the quantitative determination of sesquiterpenoids from various species of Artemisia plant samples were developed. By LC–UV, LC–ELSD, the separation was achieved by reversed-phase chromatography on a C18 column with water and acetonitrile both containing 0.025% trifluoroacetic acid as the mobile phase. In the LC–MS system, trifluoroacetic acid was replaced by 0.1% formic acid. The wavelength used for quantification of sesquiterpenoids with a diode array detector was 205 nm. The limits of detection by LC–MS was found to be 5, 10, 25, 50, 50 ng mL^?1. The limits of detection by LC–UV and LC–ELSD were found to be 5.0, 3.0, 100, 100, 7.5 μg mL^?1, by LC–UV and 50, 25, 30, 100 and 75 μg mL^?1 by LC–ELSD. LC–mass spectrometry coupled with electrospray ionization (ESI) interface is described for the identification and quantification of sesquiterpenoids in various plant samples. This method involved the use of the [M + H]⁺ ions of sesquiterpenoids in the positive ion mode with extractive ion monitoring.     

Study on the Bleaching Mechanism of Indigo—carmine Catalyzed by Laccase Using EFA and MCR—ALS Methods

The bleaching of indigo-carmine catalyzed by laccase was monitored on-line by UV/Vis spectroscopy.The resulted data were analyzed by evolving factor analysis(EFA) and multivariate curve resolution(MCR),and the reaction mechanism was proposed.     

Py–GC–MS examination of intermediates in the vapor from rapid pyrolysis of larch wood and its model components

Py–GC–MS was used to examine the components of vapor from rapid pyrolysis of larch wood and its model components, i.e. example cellulose, xylan, and lignin, and their mixture in accordance with the proportion of the components in larch wood. In this study, a total of 97 compounds in 12 categories were identified in the pyrolysis vapor and were compared. It was found that the most abundant chemical species in these five types of pyrolysis vapor were different. Saccharides and ketones were the major compounds in the pyrolysis vapor from microcrystalline cellulose and xylan, respectively, whereas the most abundant compounds in the pyrolysis vapor from alkaline lignin were sulfur compounds and phenols. Saccharides and ketones were major components of the pyrolysis vapor from MMC, whereas the main compounds in the pyrolysis vapor from larch wood were ketones, phenols, aldehydes, and saccharides. The different composition of the pyrolysis vapor from larch wood and its model mixture was explained on the basis of their different structural frameworks and the non-structural components of larch wood. It was also concluded that the presence of non-structural components, including extractives and ash, affect the pyrolysis reaction of larch wood. Nevertheless, the detailed patterns of this process must be further studied.     

Study on degrees of mesomorphic zone of polymer. Ⅲ.Determination of the degree of crystallinity of Eucommia Ulmoides gum by VTFTIR and VTWAXD

Eucommia Ulmoides (EU) gum will crystallize easily at room temperature due to the regular trans-1,4-polyisoprene (TPI) molecular structure. Around the skeleton stretching vibration band of TPI, its FTIR spectrum showed 5 weak crystalline peaks decrease as temperature increase, and there are also two amorphous peaks (845 cm⁻¹ and 668 cm⁻¹) increase as temperature increase. According to this phenomenon, Variable Temperature Fourier Transform Infrared Spectrum (VTFTIR) and Variable Temperature Wide Angle X-ray Diffraction (VTWAXD) have been taken to analyze the degree of crystallinity of EU gum. In addition to the ratio of crystalline zone, the result determined by VTFTIR also involve the mesomorphic zone, which make it higher than the result determined by VTWAXD. Through the comparative analysis of VTFTIR and VTWAXD, it has been proved that the ratio of crystalline zone, mesomorphic zone, amorphous zone in EU gum were respectively 39.8%, 27.6%, 32.6% at room temperature. Based on the Density Measurement and the three-phase model theory, the density gradient function of the mesomorphic zone of EU gum was firstly proposed. Below 60 °C, the density of the mesomorphic does not change with the temperature, approximately 0.931g/cm⁻³. Above 60 °C, the density of the mesomorphic decreases with the temperature increasing, and finally drops to 0.905g/cm⁻³ at 80 °C, which is equal to the density of the complete amorphous zone.     

A Rapid and Simple UPLC-MS–MS based Simultaneous Determination of the Medicinally Important E- and Z-Guggulsterone from Oleogum-Resins of Naturally Occurring Commiphora wightii Plants

A fast and simple method for simultaneous detection and quantification of the medicinally important E- and Z-guggulsterone from raw oleogum-resin of Commiphora wightii by UPLC was developed. Both E- and Z-guggulsterone were extracted from naturally occurring resin samples using ethyl acetate and methanol. Chromatographic separation of the analytes and their respective standards were performed on an Acquity UPLC BEH C₁₈ column followed by UV as well as a triple quadrupole detector in positive ionization mode. A linear gradient elution profile followed; mobile phase consisted of acetonitrile and 2 mM ammonium acetate in water. The method was validated over a range of 6.25 to 100 ng mL^?1 for both the guggulsterones. The calibration curves were linear with correlation coefficients of 0.9998 for E-guggulsterone and 0.9999 for Z-guggulsterone. The LOD and LOQ were 1.65 and 5.02 ng mL^?1 for E-guggulsterone and 2.57 and 7.79 ng mL^?1 for Z-guggulsterone respectively. The average recovery of E-guggulsterone (104.63%) and Z-guggulsterone (104.33%) achieved from spiked samples were consistent and reproducible. The intra- and inter-day assay precision of the analytes over the entire concentration range was less than 2%. The developed method required only 6 min to complete a run including 1 min to equilibrate the system and hence suitable for high throughput applications. Efficiency, reliability and accuracy of the developed method were evaluated by analyzing resin sample from different C. wightii populations. The result of this study offers improvement in terms of speed and sensitivity as compared to previously reported methods.     

Experimental Study on the Determination and Degradation of Pyoluteorin in Soil via CE with Soxhlet’s Extraction and Field-Amplified Sample Stacking

A sensitive analytical method based on capillary electrophoresis with field-amplified sample stacking, Soxhlet’s extraction and ultrasonic extraction for studying the degradation of trace amounts of pyoluteorin (Plt, a broad-spectrum fungicide produced by fluorescent Pseudomonas) in soil samples was first developed. The limits of detection and the limits of quantification for Plt of the developed method were 0.107 and 0.36 μg mL^?1, respectively. The recoveries of Plt at three spiking concentrations of 500, 200, and 50 μg kg^?1 were 94.18, 79, and 78.25%, respectively. In this communication, we successfully performed the investigation on the dynamic residue of Plt during its decomposition in agriculture soil using the method developed. The calculated t _1/2 values for Plt residue in near-surface and rhizosphere soil were 42.26 and 32.84 h, respectively. The results show that Plt has good environmental compatibility.     

A fast and effective routine method based on HS-SPME–GC–MS/MS for the analysis of organotin compounds in biota samples

This work validated an automated, fast, and low solvent- consuming methodology suited for routine analysis of tributyltin (TBT) and degradation products (dibutyltin, DBT; monobutyltin, MBT) in biota samples. The method was based on the headspace solid-phase microextraction methodology (HS-SPME), coupled with gas chromatographic separation and tandem mass-spectrometry (GC–MS/MS). The effectiveness of the matrix-matched signal ratio external calibration was tested for quantification purposes. The exclusion of matrix influences in the calibration curves proved the suitability of this versatile quantification method. The method detection limits obtained were of 3 ng Sn g⁻¹ dw for all the analytes. The analysis of references materials showed satisfying accuracy under optimum calibration conditions (% recovery between 87–111%; |Z-scores|<2). The repeatability RSD% and intra-laboratory reproducibility RSD% were lower than 9.6% and 12.6%, respectively. The work proved the remarkable analytical performances of the method and its high potential for routine application in monitoring organotin compounds (OTC).     

A Study on 4,4′-Diaminobenzene Sulfonanilide (DABSA) and the Properties of Dyes Derived from DABSA

Ｓｉｎｃｅｂｅｎｚｉｄｉｎｅｉｓａｋｎｏｗｎｃａｒｃｉｎｏｇｅｎ ,ｉｄｅｎｔｉｆｙｉｎｇｐｏｔｅｎｔｉａｌｒｅｐｌａｃｅｍｅｎｔｓｆｏｒｂｅｎｚｉｄｉｎｅｈａｓｂｅｃｏｍｅａｎｉｍｐｏｒｔａｎｔｒｅｓｅａｒｃｈｐｒｏｊｅｃｔｉｎｃｏｌｏｒｃｈｅｍｉｓｔｒｙ .Ｏｎｅｏｆｔｈｅｃｏｍｐｏｕｎｄｓｅｘａｍｉｎｅｄｉｓ 4,4′ ｄｉａｍｉｎｏｂｅｎｚｅｎｅｓｕｌｆｏｎａｎｉｌｉｄｅ(ＤＡＢＳＡ) .ＡｓｅｒｉｅｓｏｆｄｙｅｓｄｅｒｉｖｅｄｆｒｏｍＤＡＢＳＡｈａｓｂｅｅｎｄｅｖｅｌｏｐｅｄａｎｄｃｏｍｍｅｒｃｉ…     

Effect of Silica Gel ‘G’ on the Ion Exchange Behaviour of Antimonic Acid Thin Layers in The Chromatographic Study of Anions in Some Aqueous Organic Acid Systems: Determination of Ferricyanide and Dichromate Ions

Abstract

The ion exchange potential of antimonic acid and silica gel ‘G’ has been explored in thin layer chromatographic studies for the separation of anions. Several important and difficult binary separations of anions have been achieved as a result of these studies. Io^? ₃-Bro^? ₃, I^?-Io^? ₃, Io^? ₄-Io^? ₃, Io^? ₄-Po^?- ₄, Br^?-Bro^? ₃, Aso^?- ₄-Cro^?- ₄, S₂o^?- ₃-Po^?- ₄, CNS^?-S₂o^?- ₃, Io^? ₄-Cro^?- ₄, Bro^? ₃-Cro^?- ₄, Io^? ₃-Cr₂o^?- ₇ and s₂o₃-Cro^?- ₄ etc. are separations of analytical interest. Besides, a rapid microgram determination of [Fe(CN)₆]^3? (1–10 μg) and Cr₂o^2- ₇ (2–10 μg) ions have been made.