Separation and purification of active ingredients in tobacco by free-flow electrophoresis.

The active ingredients from tobacco extracts were continuously separated and purified using a homemade free-flow electrophoresis apparatus. A rectangular free flow electrophoresis device was constructed for the continuous separation and preparation, and the operating conditions of the device were optimized. The fractions obtained from the free-flowing component collection unit were then detected by HPLC and GC-MS. The results showed that a 90% methanol-water solution could maximize the extraction of the active components from tobacco. Chlorogenic acid and nicotine were enriched in three and four of 24 fractions, respectively, after free-flow isoelectric focusing electrophoresis. 2-Hydroxy-2-cyclopentene-1-one, 1-(2-methyl-1,3-oxathiolan-2-yl) ethanone, nornicotine, cotinine, and scopolamine were separated and enriched synchronously. Overall, the use of free-flow electrophoresis technology for the separation and purification of the active substances in tobacco can improve the comprehensive utilization rate of tobacco.

[Trapping array-based preparative two-dimensional liquid chromatography for the purification of four components in tobacco leaves].

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.

A simple and rapid approach for on-site analysis of nicotine in tobacco based on a screen-printed electrode as an electrochemical sensor.

In this study, we report a portable kit consisting of a portable workstation, gold screen-printed electrode (SPE), 0.45 µm filter membrane, phosphate buffer solution (PBS), and acetic acid (1%) for point-of-use (POU) analysis of nicotine in tobacco. The activated-screen-printed electrode (A-SPE) displayed superior electron transmission efficiency, and the A-SPE without modification was employed for high-performance analysis of nicotine in actual tobacco after simple sample pretreatment. Remarkably, the fabricated nicotine sensor exhibited a broad working range of 10-100 µg g-1, a low limit of detection (LOD) of 6.4 µg mL-1, good stability, selectivity, and practicality under the optimal conditions. The method was applied to the determination of nicotine in (spiked) samples. Satisfactory recovery results demonstrated that the as-prepared portable kit method with outstanding electrocatalysis ability was feasible for analysis of nicotine in tobacco. Moreover, the values obtained using the A-SPE were in good agreement with those determined by gas chromatography-flame ionization detection (GC-FID), which confirms the feasibility and validity of the present method. The results of the as-proposed portable kit provided a new strategy for analyzing nicotine in actual tobacco samples.

Nickel-catalyzed reductive 1,3-diene formation from the cross-coupling of vinyl bromides.

Facile construction of 1,3-dienes building upon cross-electrophile coupling of two open-chain vinyl halides is disclosed in this work, showing moderate chemoselectivities between the terminal bromoalkenes and internal vinyl bromides. The present method is mild and tolerates a range of functional groups and can be applied to the total synthesis of a tobacco fragrance solanone.

[Bacterial Diversity and Community Structure Antibiotic-resistant Bacteria in Bioaerosol of Animal Farms].

Confined animal feeding operations generate high concentrations of airborne antibiotic-resistant bacteria, including pathogenic strains that may pose a health risk to both animals and farm workers and pollute the local air environment. In this study, tetracycline and erythromycin-resistant bacteria were used as examples to study the biodiversity and community structure of airborne antibiotic-resistant bacteria in animal farms. The Anderson sampler was used to collect bioaerosols samples from the inside environment and outside atmospheric environments. A comparative analysis of biological differences of antibiotic-resistant bacteria was conducted on fine and coarse particles, bioaerosol samples inside the house, fecal samples, and inside and outside bioaerosol samples based on the result of the Illumina MiSeq sequencing. The key genus that drives the above differences was also studied. Results showed that the biodiversity of airborne erythromycin-resistant bacteria was higher than that of airborne tetracycline-resistant bacteria, and the biodiversity of bioaerosol samples in the house was higher than that in fecal samples. There were no significant differences in the biodiversity and community structure of airborne antibiotic-resistant bacteria between fine and coarse particles. Actinobacteria is one of the key bacteria responsible for the differences between erythromycin-resistant bacteria and other bacterial populations. Staphylococcus is one of the key genera of tetracycline-resistant flora that is distinguished from erythromycin resistance and all bacterial flora. The results of the community structure showed that there was no significant difference in the dominant flora and the community structure of tetracycline and erythromycin-resistant bacteria. The community structure of feces and bioaerosol samples is different at the genus level, and the dominant bacteria are likewise different. The results of this study provide basic data for the accurate assessment of the current status of antibiotic-resistant bacteria in animal farms and their ecological risks.

A facile approach for rapid on-site screening of nicotine in natural tobacco.

Nicotine (Nic) exposed to the environment which comes from tobacco products is the main addictive agent and specific classes of hazardous compound that merit concern. In this study, we have established a fast and reliable method to achieve specific detection of Nic in natural nicotiana tabacum within 30 s through a miniaturized platform based on screen printed gold electrode (SPE). A simple electrochemical pretreatment mean was employed on gold surface that led to the exposure of Au (111) facet and a convenient sample pretreatment method was adopted to realize the extraction of Nic in tobacco. The present electrochemical sensor exhibits an ample range of sensing from 10 µg/g to 200 µg/g, which is able to compliance with tobacco industry testing standards of actual samples. Over 60 sampling points from different origins in China or other countries were performed with direct analysis using this method and satisfactory results have been obtained. The proposed approach was demonstrated to be a very promising platform for significantly improving analytical efficiency in laboratories as well as for monitoring the source reduction control of Nic in the environment.

Separation and Analysis of Sucrose Esters in Tobacco by Online Liquid Chromatography-Gas Chromatography/Mass Spectrometry.

In this work, a strategy of in-series combination of ultrasound-assisted extraction and online LC-GC/MS was constructed for effective separation and analysis of sucrose esters in tobacco. Sucrose esters were first extracted by ultrasound-assisted extraction with high efficiency and easyhandling. Online LC-GC/MS was then applied for sucrose ester clean-up and analysis. To better evaluate the effectiveness of this strategy, we limited our focus to five groups of sucrose ester isomers. Each group differed in mass from the next by 14 Da. The obtained coefficient of the calibration curve was 0.9986. Limit of detection (LOD) and limit of quantitation (LOQ) were 0.05 and 0.16 µg/ mL, respectively. The recovery was above 90% and the reproducibility was below 4%. This strategy was subsequently applied to the comparison of relative amounts of five groups of sucrose esters extracted from three different parts of aromatic tobacco. The satisfactory performance indicated that this strategy has great prospect for the rapid and high-throughput analysis of sucrose esters in tobacco.

Quantification of Dopamine in Brain Microdialysates with High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

The dopamine level in the brain and the mesolimbick dopaminergic system are responsible for nicotine addiction. In the present study, extracellular dopamine in nucleus accumbens was collected by a brain microdialysis technique. Also a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with a gradient elution procedure was developed for a precise determination of dopamine in brain dialysate. The retention time of dopamine was about 11.32 min. The linear range was 20 - 1000 pg/mL. The limit of detection (LOD) and the limit of qualification (LOQ) were 5 and 20 pg/mL, respectively. The recovery ranged from 98.2 to 109.0%, and both the intra-RSD and inter-RSD were below <9%, respectively. The probe recovery for dopamine in this brain microdialysis experiment was about 25%. Finally, the dopamine concentrations in the rat brain microdialysates were determined, and the pharmacokinetics of extracellular dopamine in the brain nucleus accumbens after an intravenous injection of nicotine was successfully evaluated.

Tuning the adsorption behaviors of water, methanol, and ethanol in a porous material by varying the flexibility of substituted groups.

Exploring the adsorption and separation of water, methanol, and ethanol is important concerning the use of a sustainable energy source from biofuel. In this paper, the effects of the flexibility of substituted groups have been studied based on three iso-reticular metal-organic frameworks (MOFs), in which the pore surface is decorated with propargyl (-CH2-C[triple bond, length as m-dash]CH), allyl (-CH2-CH[double bond, length as m-dash]CH2), and propyl (-CH2-CH2-CH3) groups respectively. These substituted groups stretch into the channel, acting as gates, and the gate-opening for guests is controlled by the flexibility as well as host-guest interactions. Our study results indicate that (i) the adsorption capacity of water, methanol and ethanol enhances accordingly with the increase of the flexibility of substituted groups; (ii) the adsorptive discrimination of water, methanol, and ethanol on this porous sorbent could be tuned by varying the substituted groups.

A novel fully automated on-line coupled liquid chromatography-gas chromatography technique used for the determination of organochlorine pesticide residues in tobacco and tobacco products.

In this study, a novel fully automated on-line coupled liquid chromatography-gas chromatography (LC-GC) technique was reported and applied for the determination of organochlorine pesticide residues (OCPs) in tobacco and tobacco products. Using a switching valve to isolate the capillary pre-column and the analytical column during the solvent evaporation period, the LC solvent can be completely removed and prevented from reaching the GC column and the detector. The established method was used to determinate the OCPs in tobacco samples. By using Florisil SPE column and employing GPC technique, polarity impurities and large molecule impurities were removed. A dynamic range 1-100ng/mL was achieved with detection limits from 1.5 to 3.3µg/kg. The method exhibited good repeatability and recoveries. This technology may provide an alternative way for trace analysis of complex samples.

Preparation of phenyl group-functionalized magnetic mesoporous silica microspheres for fast extraction and analysis of acetaldehyde in mainstream cigarette smoke by gas chromatography-mass spectrometry.

Acetaldehyde is regarded as a toxic mainstream cigarette smoke constituent, and measurement of acetaldehyde in complex real samples is difficult owing to its high volatility and reactivity. In this work, phenyl group-functionalized magnetic mesoporous microspheres were developed as the solid-phase extraction sorbents for enrichment and analysis of acetaldehyde in mainstream cigarette smoke. The functional magnetic microspheres were first synthesized through a facile one-pot co-condensation approach. The prepared nanomaterials possessed abundant silanol groups in the exterior surface and numerous phenyl groups in the interior pore-walls, as well as a large surface area (273.5m(2)/g), strong superparamagnetism and uniform mesopores (3.3 nm). Acetaldehyde in mainstream cigarette smoke was collected in water and derivatizated with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine. The formed acetaldehyde oximes were extracted and enriched by the prepared adsorbents via π-π interactions and subsequently analyzed using GC-MS. Extraction conditions such as amounts of sorbents, eluting solvent, adsorption and desorption time were investigated and optimized to achieve the best efficiency. Method validations including linearity, recovery, repeatability, and limit of detection were also studied. It was found that the suggested methodology provided low detection limit of 0.04 mg/mL, good recovery of 88-92%, intra-day and inter-day RSD values of 4.5% and 10.1%, and linear range of 0.25-4 mg/mL (R(2)=0.999). The results indicated that the proposed method based on phenyl-functionalized magnetic mesoporous microspheres was rapid, efficient and convenient for the enrichment and analysis of acetaldehyde in tobacco.

Surface properties of solid materials measured by modified inverse gas chromatography.

A novel modified inverse gas chromatography (IGC) method has been developed to investigate the surface properties of solid materials. On the modified IGC system, the every adjusted retention time of miscellaneous probe molecules can be rapidly calculated within only one sample injection through wisely induction a capillary column and two detectors, i.e., flame ionization detector (FID) and thermal conductivity detector (TCD). In the system, the relative dead time can be acquired from FID detector while the retention time can be obtained from TCD detector simultaneously. The significant advantage of our design is that, experimental time is greatly saved compared to the traditional IGC. In addition, the new system is capable of distinguishing variety surface properties of porous materials. Two types of active carbon samples were tested, and the results showed that their thermodynamic parameters were quite different, indicating that the samples have opposite acidic/basic properties. The use of IGC would be an effective tool to evaluate the physiochemical data of solid materials.

Development of solvent micro-extraction combined with derivatization.

Solvent microextraction (SME), such as single-drop microextraction (SDME), hollow-fiber liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME), has been explored for its ability to cover a wide range of analytes. Microextraction, combined microextraction with derivatization can greatly improve separation, detectability and compound identification, expand its scope of application, and improve the effect of analysis. In this view, the article not only highlights the development of the microextraction technology such as SDBE, HF-LPME and DLLME, but also improves the key strategies of microextraction coupled to derivatization in analytical chemistry. In order to encourage further development of microextraction-derivatization, its coupling with different analytical techniques such as GC or GC-MS, HPLC, and the other technique has also been discussed.

Analysis of amino acids in tobacco by derivatization and dispersive liquid-liquid microextraction based on solidification of floating organic droplet method.

A new one-step derivatization and microextraction technique was developed for determination of amino acids in tobacco samples. In the proposed method, amino acids were derivatized with isobutyl chloroformate (IBCF) in aqueous solution. The derivatives were extracted by dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO). Parameters affecting the extraction efficiency were investigated in detail. The optimum conditions were as follows: a mixture of 500µL acetone, containing 40µL 2-dodecanol, was rapidly injected by syringe into the 2mL water sample. After centrifugation, the 2-dodecanol droplets were floated at the top of the tube. Then, the tube was cooled in an ice bath. After 5min the solvent had solidified and was then transferred into a conical vial; it melted quickly at room temperature and it was injected into a gas chromatograph for analysis. Under the optimum conditions, the limits of detection were of the order of 0.12-2.82µg/mL. The calibration curves showed good linearity over the investigated concentration range between 0.5 and 200µg/mL with a coefficient of estimation (R(2))>0.9887 for GC-MS (SIM). The proposed method is an alternative approach to the quantification of amino acids in tobacco samples.

Analysis of the volatile components emitted from cut tobacco processing by gas chromatography/mass spectrometry thermal desorption system.

A sensitive and reliable method was developed for the determination of volatile components emitted from cut tobacco processing using thermal desorption (TD) followed by gas chromatography-mass spectrometry (GC-MS). In the work, to obtain the optimal sorbent, three commercial sorbents were compared in terms of adsorption efficiency. The carbotrap 349 was found to have the best performance. The desorption conditions were also studied. Validation of the TD-GC-MS method showed good sensibility, linearity and precision. Limits of detection ranges were from 0.20 to 3.6 ng. Calibration curves were obtained by plotting peak area versus concentration and the correlation coefficients relating to linearity were at least 0.9984. The analysis was reproducible, with relative standard deviation (n=8) within 6.5%. The target compound breakthrough examination showed no significant losses when about 1500 ng standards were prepared. In order to evaluate the performance of the analytical method in the volatile constituents of cut tobacco, samples were taken in industrial areas of cut tobacco processing. Recoveries ranged from 85.1% to 110% for all the compounds and good precision had been reached (RSD<13.3). The results proved that TD-GC-MS was a simple, rapid and accurate method for the analysis of volatile compounds emitted from cut tobacco drying step.

Development of single-drop microextraction and simultaneous derivatization followed by GC-MS for the determination of aliphatic amines in tobacco.

In this work, for the first time, headspace (HS) single-drop microextraction and simultaneous derivatization followed by GC-MS was developed to determine the aliphatic amines in tobacco samples. In the HS extraction procedure, the mixture of derivatization reagent and organic solvent was employed as the extraction solvent for HS single-drop microextraction and in situ derivatization of aliphatic amine in the samples. Fast extraction and simultaneous derivatization of the analytes were performed in a single step, and the obtained derivatives in the microdrop extraction solvent were analyzed by GC-MS. The optimized experiment conditions were: sample preparation temperature of 80 degrees C and time of 30 min, HS extraction solvent (the mixture of benzyl alcohol and 2,3,4,5,6-pentafluorobenzaldehyde) volume of 2.0 microL, extraction time of 90 s. With the optimal conditions, the method validations were also studied. The method has good linearity (R(2) more than 0.99), accepted precision (RSD less than 13%), good recovery (98-104%) and low limit of detection (0.11-0.97 microg/g). Finally, the proposed technique was successfully applied to the analyses of aliphatic amines in tobacco samples of seven different brands. It was further demonstrated that the proposed method offered a simple, low-cost and reliable approach to determine aliphatic amines in tobacco samples.

Determination of volatile organic acids in tobacco by single-drop microextraction with in-syringe derivatization followed by GC-MS.

In this work, the novel technique based on headspace single-drop microextraction with in-syringe derivatization followed by GC-MS was established to determine the volatile organic acids in tobacco. The parameters for headspace single-drop microextraction and in-syringe derivatization were optimized, including extraction time, and volume of derivatization reagent and in-syringe derivatization time. The method validations including linearity, precision, recovery and LOD were also studied. The obtained results illustrated that the optimized technique was easy, highly efficient and sensitive. Finally, the proposed method was successfully applied to the analyses of volatile organic acids in tobacco samples with seven different brands. It was further demonstrated that the present technique developed in this study does offer a simple and fast approach to determine volatile organic acids in tobacco.

Microwave-assisted silylation followed by gas chromatography/mass spectrometry for rapid determination of ergosterol in cigarettes.

Ergosterol is one of the important precursors of tumorigenic polynuclear aromatic hydrocarbons. To the best of our knowledge, a large amount of ergosterol is present in moldy cigarettes, which derives from fungal contaminations. Thus, the development of a simple, fast, and efficient method for the analysis of ergosterol is in great demand. In this paper, GC/MS following microwave-assisted silylation (MAS) was developed for the rapid quantitative analysis of ergosterol in cigarettes for the first time. In our work, total ergosterol in cigarettes after NaOH saponification was extracted with hexane, and then was fast derivatized with bis(trimethylsilyl)trifluoroacetamide (BSTFA) under microwave irradiation. Finally, the ergosterol trimethylsilyl derivative was analyzed by GC/MS. Derivatization conditions including microwave reaction solvent, irradiation time, and power were investigated. Method validations (linear range, LOD, precision, and recovery) were also studied. The results showed that the proposed method provided a fast, simple, and sensitive approach for the determination of ergosterol in cigarettes. Finally it was successfully applied to the analysis of ergosterol in normal and mildewy cigarettes.

Development of C18-functionalized magnetic silica nanoparticles as sample preparation technique for the determination of ergosterol in cigarettes by microwave-assisted derivatization and gas chromatography/mass spectrometry.

Ergosterol is one of the important precursors of tumorigenic polynuclear aromatic hydrocarbons. A large amount of ergosterol is present in mildewy cigarettes, which derives from fungal contaminations. In this paper, a novel approach based on C(18)-functionalized magnetic silica nanoparticles (C(18)-f-MS NPs) coupled with microwave-assisted derivatization and gas chromatography/mass spectrometry (GC/MS) was developed for the rapid enrichment and determination of ergosterol in cigarettes. Due to that, microwave-assisted derivatization requires very short time (several minutes), and the extraction and concentration of ergosterol become the key step in the sample preparation process. In this study, the prepared C(18)-f-MS NPs with its unique properties (high surface area and strong magnetism) provided an efficient way for extraction and concentration of ergosterol in the samples. Additionally, the analyte of ergosterol adsorbed with C(18)-f-MS NPs in cigarettes can be simply and rapidly isolated (only about 2s) through placing a strong magnet on the bottom of container. In this work, different parameters such as added amounts of C(18)-f-MS NPs, extraction temperature, and extraction time were optimized to enhance the extraction efficiency. Method validations (linear range, detection limit, precision, and recovery) were also studied. The results obtained by the optimal conditions showed that the proposed method based on C(18)-f-MS NPs was a simple, high efficient, and had a rapid approach for the enrichment of ergosterol in cigarettes and was successfully applied to the analysis of ergosterol in normal and mildewy cigarettes followed by microwave-assisted derivatization and GC/MS.

High-performance liquid chromatographic determination of vertilmicin in rat plasma using sensitive fluorometric derivatization.

A sensitive and reliable high-performance liquid chromatographic method was developed for the determination of vertilmicin in rat plasma. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C(18) reversed-phase chromatography allowed the fluorimetric detection of vertilmicin. Optimal conditions for the derivatization of vertilmicin are described. The limit of quantification was 0.02 mg/L. The pharmacokinetics of vertilmicin was studied in 24 rats following intramuscular injection (i.m.) of different doses (4, 8, 16, 32 mg/kg of body weight). The pharmacokinetic parameter values were estimated by use of 3P97 program. In this study, we assessed the dose proportionality of vertilmicin after single intramuscular injection doses and obtained new information on the pharmacokinetics of the compound.