Hongfei Zhang

Magnetic graphene as modified quick, easy, cheap, effective, rugged and safe adsorbent for the determination of organochlorine pesticide residues in tobacco

In this study, magnetic graphene was used as modified quick, easy, cheap, effective, rugged and safe (QuEChERS) adsorbent for the determination of organochlorine pesticide (OCPs) residues in tobacco. To achieve the optimum conditions of modified QuEChERS procedure toward target analytes, several parameters affecting the clean-up efficiency including the amount of the adsorbent and clean-up time were investigated. Under the optimized conditions, a method for the determination of 26 OCPs residues in tobacco was established by coupling the modified QuEChERS procedure to on-line gel permeation chromatography-gas chromatography-tandem mass spectrometry (on-line GPC-GC-MS(2)). The limits of detection of proposed method for 26 OCPs residues ranged from 0.01275 to 3.150ng/g. And good linearities of the proposed method were obtained with coefficients of determination (R(2)) greater than 0.9985 for all target analytes. Good reproducibility of method was obtained as intra- and inter-day precisions, the relative standard deviations were less than 11.1 and 15.0%, respectively. The apparent recoveries were in the range of 64-126% at different concentrations for real samples. Compared with the reported methods for the determination of OCPs residues in tobacco, the proposed method has the advantages of simple to operate, low cost and high clean-up ability. Finally, the method was successfully applied to the analysis of OCPs residues in real samples.

Simultaneous determination of polycyclic aromatic hydrocarbons and tobacco-specific N-nitrosamines in mainstream cigarette smoke using in-pipette-tip solid-phase extraction and on-line gel permeation chromatography-gas chromatography–tandem mass spectrometry

In this study, a silica/primary secondary amine (SiO2/PSA) was used as an in-pipette-tip solid phase extraction (SPE) sorbent for the simultaneous determination of polycyclic aromatic hydrocarbons (PAHs) and tobacco-specific N-nitrosamines (TSNAs) in mainstream cigarette smoke (MSS). We investigated several parameters including an extraction procedure of total particulate matter, type and amount of sorbent and on-line gel permeation chromatography parameters to obtain optimum conditions for a new strategy to target analytes. Under the optimized conditions, we developed a method for the simultaneous determination of PAHs and TSNAs in MSS by coupling in-pipette-tip SPE procedures to an on-line gel permeation chromatography-gas chromatography-tandem mass spectrometry (on-line GPC-GC-MS(2)). Our method had limits of detection for target analytes ranging from 0.01 to 0.23ng/cig. Good linearities were obtained with coefficients of determination (R(2)) greater than 0.9984 for all target analytes. Good reproducibility was obtained as intra- and inter-day precisions, and the relative standard deviations were less than 11.4 and 13.3%, respectively. The recoveries were in the range of 77.1-108.6% at different concentrations for real samples. Compared to previous standard methods for the determination of PAHs and TSNAs in MSS, our method was highly effective, fast, and had low consumption of organic solvent and a high degree of automation. Finally, our method successfully analyzed PAHs and TSNAs in real samples, and no significant deviations were observed when compared to similar analysis using standard methods.

Au nanocrystals grown on a better-defined one-dimensional tobacco mosaic virus coated protein template genetically modified by a hexahistidine tag

In this paper, tobacco mosaic virus (TMV) coated protein (CP) was genetically modified by introducing a hexahistidine tag into it for a well-defined one-dimensional template, on which Au nanocrystals (NCs) were grown. The results showed that genetic modification could not only ameliorate the one-dimensional structure of the template, but also improve the growth density of Au NCs on the template. This indicated that genetic modification could be an effective method to modulate the structure of the TMVCP template-based nanocomposites allowing for a broader application of them.

Chemical Analysis and Simulated Pyrolysis of Tobacco Heating System 2.2 Compared to Conventional Cigarettes

Introduction Tobacco Heating System 2.2 (THS 2.2, marketed as iQOS) is a heat-not-burn (HNB) tobacco product that has been successfully introduced to global markets. Despite its expanding market, few independent and systematic researches into THS 2.2 have been carried out to date. Methods We tested a comprehensive list of total particulate matter (TPM), water, tar, nicotine, propylene glycol, glycerin, carbon monoxide, volatile organic compounds, aromatic amines, hydrogen cyanide, ammonia, N-nitrosamines, phenol, and polycyclic aromatic hydrocarbon under both ISO and HCI regimes. We also simulated pyrolysis of THS 2.2 heating sticks and made comparisons with conventional cigarette tobacco fillers using comprehensive gas chromatography-mass spectrometry (GC × GC-MS) to determine whether the specially designed ingredients help reduce harmful constituents. Results Other than some carbonyls, ammonia, and N-nitrosoanabasine (NAB), the delivered releases from THS 2.2 were at least 80% lower than those from 3R4F. Tar and nicotine remained almost the same as 3R4F. Interestingly, the normalized yield of THS 2.2 to 3R4F under the HCI regime was lower than that under the ISO regime. Conclusions THS 2.2 delivered fewer harmful constituents than the conventional cigarette 3R4F. Simulated pyrolysis results showed that the lower temperature instead of specially designed ingredients contributed to the distinct shift. In particular, if smoking machines are involved to evaluate the HNB products, smoking regimes of heat-not-burn tobacco products should be carefully chosen. Implications To our knowledge, few independent studies of HNB products have been published. In this paper, a comprehensive list of chemical releases was tested systematically and compared to those from 3R4F. Although THS 2.2 generates lower levels of harmful constituents, the nicotine and tar levels were almost identical to 3R4F.The results should be discussed carefully in the future when assessing the dual-use with other conventional cigarettes, nicotine dependence of HNB products, etc. This study also suggests that regulatory agencies should pay attention to the smoking regimes that are adopted to evaluate HNB tobacco products.

Determination of Pesticide Residues in Tobacco Using Modified QuEChERS Procedure Coupled to On-line Gel Permeation Chromatography-Gas Chromatography/ Tandem Mass Spectrometry

Abstract Magnetic graphitized carbon black/primary secondary amine/magnetite (GCB/PSA/Fe3O4) composite material was used as modified QuEChERS adsorbent for the clean-up of tobacco extract. A method for the determination of ten pesticide residues in tobacco was proposed by coupling the modified QuEChERS procedure to on-line gel permeation chromatography-gas chromatography/tandem mass spectrometry (GPC-GC-MS/MS). Several parameters affecting clean-up efficiency were investigated. Under optimized conditions including 3.30–5.30 min of on-line GPC collection time, 80 mg of adsorbent amount, and 1.0 min of clean-up time, the limits of detection for target analytes ranged from 0.940 ng L−1 to 100 ng L−1. The linear regression data of the proposed method were obtained with correlation coefficients ≥ 0.9989 for all target analytes. The relative standard deviations for both intra- and inter-day were less than 15.1% and 19.8%, respectively. The recoveries were in the range of 68.8%–132.2% for real samples. Finally, the method was successfully applied to the analysis of pesticide residues in real samples, and the results were in agreement with those obtained from the current standard method.

Environmentally friendly method for the determination of acrylamide and trimethylolpropane in paper packaging materials by liquid chromatography with tandem mass spectrometry

A simple, rapid, and environmentally friendly method was developed for the determination of acrylamide and trimethylolpropane in paper packaging materials. No organic solvent was used and the matrix effect was investigated. The extract was directly analyzed by liquid chromatography with tandem mass chromatography for quantification and confirmation. The chromatographic separations were performed on a ZORBAX HILIC Plus (2.1 mm × 150 mm, 3μm; Agilent, USA) column with only one mobile phase (100% water). Calibration curves for acrylamide and trimethylopropane were achieved with concentrations ranging from 0.4 to 20 mg/kg and the corresponding r(2) values were 0.998 and 0.999, respectively. The recoveries were >85% with relative standard deviations <10%. The validated method was applied to the analysis of 50 real samples, and positive results were obtained for 30 samples. The result indicated that trimethylolpropane is associated with inks and printing activity and acrylamide is widely used as a papermaking additive in many paper packages. The concentrations of acrylamide and trimethylolpropane ranged from 0.41 to 7.5 and 0.50 to 8.8 mg/kg, respectively. The results of this study revealed that this method could be used accurately and precisely.

Enantiomeric composition of nicotine in tobacco leaf, cigarette, smokeless tobacco, and e-liquid by normal phase high-performance liquid chromatography.

Evaluating the source of nicotine in e-liquid is a problem. Tobacco-derived nicotine contains predominantly (S)-(-)-nicotine, whereas tobacco-free nicotine products may not. Thus, we developed a new normal phase high-performance liquid chromatography method to determinate the enantiomeric composition of nicotine in 10 kinds of flue-cured tobacco, 3 kinds of burley, 1 kind of cigar tobacco, 2 kinds of oriental tobacco, 5 kinds of Virginia cigarette, 5 kinds of blend cigarette, 10 kinds of e-liquid, and 4 kinds of smokeless tobacco. The amount of (R)-(+)-nicotine ranged from ~0.02% to ~0.76% of total nicotine. An e-liquid sample had the highest level of (R)-(+)-nicotine. The extraction and purification processes used to obtain commercial (S)-(-)-nicotine from the tobacco do not decrease the amount of (R)-(+)-nicotine in tobacco. So the amount of (R)-(+)-nicotine in samples in our work were the same as tobacco samples.

An Environmentally Friendly Method for the Determination of Pentachlorophenol in Paper Packaging Materials Using Ultrasonic-Assisted Micellar Extraction

Ultrasonic-assisted micellar extraction coupled with high-pressure liquid chromatography has been developed for the determination of pentachlorophenol (PCP) in paper packaging materials. A non-ionic surfactant, polyethylene glycol sorbitan monolaurate (Tween 20), was used for ultrasonic extraction and the method was applied to different paper packaging materials under optimized conditions. The recoveries for spiked samples were 83-90.1% and relative standard deviations were <5.0%. The limit of detection and the limit of quantification for PCP were 0.9 and 2.0 µg/g, respectively. Results confirmed that this relatively simple procedure proved satisfactory for the determination of PCP in paper packaging materials.

Determination of multiresidues of three acid herbicides in tobacco by liquid chromatography/tandem mass spectrometry.

A method to determine residues of the three acid herbicides, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, and 3,6-dichloro-2-methoxybenzoic acid (dicamba), in tobacco using LC/MS/MS is presented. Because these herbicide residues in tobacco might exist in different forms (free acid, salt, and ester), tobacco samples were first pretreated by alkaline hydrolysis and then the pH was adjusted in order to convert the residues completely to their free acid forms. Dichloromethane extraction and dispersive SPE using C18 sorbent were carried out before LC/MS/MS analysis, and quantification was performed using the internal standard method. Linearity was good for all analytes (R(2) ≥ 0.999) in the concentration range of 0.02 to 0.5 mg/kg. LODs were below 0.05 mg/kg. Recoveries ranged from 80.4 to 93.5%, and RSD was below 10%. This simple, efficient, and sensitive method can be applied to the determination of residues of the three acid herbicides in tobacco.

The Fate of Maleic Hydrazide on Tobacco during Smoking

Tobacco mainstream smoke (MSS) and sidestream smoke (SSS), butts, and ashes from commercial cigarettes and maleic hydrazide (MH) spiked cigarettes were analyzed for their MH contents. The MH transfer rates obtained for MSS ranged from 1.4% to 3.7%, for SSS ranged from 0.2% to 0.9%, and for butts ranged from 1.1% to 1.9%. And as expected, MH is absent in ashes. The transfer rate of MH into mainstream smoke is the top one during in transfer rate into main-stream, side-stream, ashes, and butts, and higher MH levels lead to more MH in smoke. Further, analysis of total MH in butts and ashes along with that in MSS and SSS indicates that much MH is destructed during the smoking process.