Search

Aims: Alternaria longipes is a causal agent of brown spot of tobacco, which remains a serious threat to tobacco production. Herein, we established a detection method for A. longipes in tobacco samples based on the principle of time‐resolved fluoroimmunoassay, in order to fulfil the requirement of rapid, sensitive and accurate detection in situ. Methods and Results: A monoclonal antibody against A. longipes was generated, and its purity and titration were assessed using western blot and ELISA. The size of europium (III) nanospheres was measured to confirm successful antibody conjugation. The method described here can detect A. longipes protein lysates as low as 0.78 ng ml−1, with recovery rates ranging from 85.96% to 99.67% in spiked tobacco. The specificity was also confirmed using a panel of microorganisms. Conclusions: The fluorescent strips allow rapid and sensitive onsite detection of A. longipes in tobacco samples, with high accuracy, specificity, and repeatability. Significance and Impact of the Study: This novel detection method provides convenience of using crude samples without complex procedures, and therefore allows rapid onsite detection by end users and quick responses towards A. longipes, which is critical for disease control and elimination of phytopathogens. [ABSTRACT FROM AUTHOR]

To determine the alkylphenol ethoxylate levels in water-based adhesives accurately, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method combined with dispersive solid phase extraction to quantify octylphenol ethoxylate (OPnEO) and nonylphenol ethoxylate (NPnEO) in water-based adhesives was developed. Water-based adhesive samples were extracted with methanol, and then purified by Ci8 dispersive solid phase extraction. The extract solution was separated by gradient elution on an Inspire HILIC chromatographic column using 5 mmol/L ammonium acetate solution and acetonitrile as the mobile phases. MS/MS analysis was performed in multiple reaction monitoring mode (MRM). The results showed that: 1) Baseline separation was realized for all OPnEO and NPnEO with different polymerization degrees within 25 minutes. 2) Under optimized conditions, the spiked recoveries for all the analytes were in the range of 79.8%-93.8% with relative standard deviations (RSDs) less than 7.0% at the addition levels of 10, 50 and 100 mg/kg. Good determination coefficients (R² ≥ 0.998 7) were achieved for all the analytes in the given concentration ranges. The LODs and LOQs were in the range of 6.64-7.42 and 22.6-24.9 µg/kg respectively. 3) Ten actual water-based adhesive samples were tested with the developed method. NPnEO was detected only in 2 samples and OPnEO was not detected in all the samples. This method is stable and accurate with strong specificity, and can be used to determine the OPnEO and NPnEO in water-based adhesives. [ABSTRACT FROM AUTHOR]

A method for the determination of three acidic herbicides, dicamba, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in tobacco and soil has been developed based on the use of liquid–liquid extraction and dispersive solid-phase extraction (dispersive-SPE) followed by UPLC–MS/MS. Two percentage of (v/v) formic acid in acetonitrile as the extraction helped partitioning of analytes into the acetonitrile phase. The extract was then cleaned up by dispersive-SPE using primary secondary amine as selective sorbents. Quantitative analysis was done in the multiple-reaction monitoring mode using stable isotope-labeled internal standards for each compound. A separate internal standard for each analyte is required to minimize sample matrix effects on each analyte, which can lead to poor analyte recoveries and decreases in method accuracy and precision. The total analysis time was <4 min. The linear range of the method was from 1 to 100 ng mL−1 with a limit of detection of each herbicide varied from 0.012 to 0.126 ng g−1. The proposed method is faster, more sensitive and selective than the traditional methods and more accurate and robust than the published LC–MS/MS methods. [ABSTRACT FROM PUBLISHER]

A liquid chromatography–tandem quadrupole mass spectrometry (LC–MS-MS) multi-residue method for the simultaneous target analysis of a wide range of pesticides in tobacco has been developed. Gradient elution has been used in conjunction with positive mode electrospray ionization tandem mass spectrometry to detect up to 118 pesticides in tobacco. The recoveries obtained for each pesticide ranged between 70 and 118% at two spiked concentration levels. Good linear relationships were observed with correlation coefficients r2 > 0.992 for all analytes. The established method was successfully applied to the determination of pesticide residues in real tobacco samples in order to validate the suitability for routine analysis. [ABSTRACT FROM PUBLISHER]

Benzo[ a ]pyrene (BaP) is considered as one of the most carcinogenic pollutants in cigarette smoke. The development of simple and sensitive BaP screening methods can help assess the risk of cigarette exposure to the human body rapidly. In this report, a rapid fluorescence immunoassay (RFIA) method for the detection of BaP is proposed, the core of which is the synthesis of bifunctional covalent antibody-DNA conjugates for target recognition and signal amplification. Based on the optimization of the SYBR Green I and PAH-BSA concentrations, as well as DNA-antibody immune complex's dilution in the RFIA system, a serial dilution of BaP was tested with this method. The results showed that the linear working range of the RFIA for BaP is 0.46 to 333 ng mL -1 , which is much wider than traditional ELISA. The detection limit was 0.32 ng mL -1 , which was more sensitive than other methods such as the redox-labeled electrochemical immunoassay method and the competitive piezoelectric biosensor. Then the cross-reactions (CR) of other PAHs in cigarette smoke were evaluated using this RFIA and found that the cross-reactions of naphthalene, anthracene, and pyrene were very low (<1%). The cross-reaction in this RFIA system can be reduced by improving the specificity of the antibody. To the best of our knowledge, this is the first time that the BaP in mainstream cigarette smoke was tested; the RFIA demonstrates fast and simple experimental manipulations and better working curves and sensitivity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

With a combination of QuEChERS method and gas chromatography-tandem mass spectrometry (GC-MS/MS) technique, three sample treatment methods (solvent exchange method, toluene dilution method, hexane liquid-liquid extraction method) were established to analyse more than one hundred pesticide residues in tobacco. The 155 pesticide analytes contained 58 organophosphorus, 28 organochlorine, 10 pyrethroids, 10 acyl amide, 11 carbamate, 7 dinitroaniline and 31 other family pesticides. Comparison of the three treatment methods was investigated on performances including matrix effect, co-extracted matrix, peak interference, recovery and the limit of quantification (LOQ). The hexane liquid-liquid extraction method gave the cleanest extract but poorer recovery; the solvent exchange and toluene dilution method could guarantee recoveries in the range of 70% and 120% for most of the 155 pesticides. We found that organophosphorus, acyl amide and carbamate pesticides exhibited relative strong matrix effects compared with organochlorine and pyrethroid pesticides. Toluene dilution method was recommended to analyse organophosphorus pesticides, and hexane liquid-liquid extraction (LLE) method was recommended to analyse organochlorine and pyrethroid pesticides.

A simple method for the determination of 132 pesticide residues in tobacco by gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS) was established. The influences of different extraction solvents, different buffer systems and different purifying agents on the recoveries of pesticides were investigated. The tobacco sample was extracted with acetonitrile, then cleaned up by the mixed sorbents of primary secondary amine (PSA) and octadecylsilane (C18E). After dried by nitrogen, the extract residue was reconstituted with n-hexane-acetone (9:1, v/v). GC-MS/MS in multi-reaction monitoring (MRM) mode was used as the detection method and triphenyl phosphate (TPP) as the internal standard. All of the 132 pesticides had good linear relationships (r2 > 0.99) between 20 microg/kg and 2 000 microg/kg. At the three spiked levels of 50, 200 and 500 microg/kg in the tobacco extract, the average recoveries of all the pesticides were in the range of 68.10% to 123.15% except for mirex and hexachlorobenzene; moreover, the relative standard deviations (RSDs) of them were between 1.79% and 19.88%. We participated in the CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) 2012's co-experiment. The results of our method and the existed standard methods had good consistency. The accurate, reliable and sensitive method can be applied to the determination of the 132 pesticide residues in tobacco for rapid screening and quantitative analysis.

A method of the determination of the carbon-centred radicals in mainstream cigarette smoke using a spin-labelled fluorophore, 4-((9-acridinecarbonyl) amino)-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO-9-AC), as a fluorescent probe is presented. After being producted by smoking in International Organization for Standardization (ISO) mode, the carbon-centred radicals in mainstream cigarette smoke were trapped by TEMPO-9-AC, a carbon-centred radical probe with a low fluorescence intensity. Then the latter was transformed to a stable diamagnetic o-alkoxyamine, a high-fluorescence compound. Finally, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to demonstrate the structures of the carbon-centred radicals, and high performance liquid chromatography with a fluorescence detector (HPLC-FLD) was used to determine the concentration of the carbon-centred radicals. The results showed that the 10 carbon-centred radicals were detected in the mainstream cigarette smoke, and the total carbon-centred radicals concentrations for 1R5F, 3R4F, CM6, and two Virginia type cigarettes, were 52.5 nmol/cig, 214.6 nmol/cig, 424.1 nmol/cig, 68.6 nmol/cig, and 334.2 nmol/cig, respectively; and there was positive relation between the concentrations of the total amount of carbon-centred radicals and the tar amounts in the mainstream cigarette smoke. The detection limit was 0.318 nmol/cig, and the relative standard deviations (RSDs) ranged from 3.5% to 9.7%. This method is suitable for the determination of the carbon-centred radicals in the mainstream cigarette smoke.

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.

A simple method for the analysis of benzo [ a ] pyrene, benzo [ a ] anthracene and chrysene in mainstream cigarette smoke using automated solid phase extraction (SPE) system-gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. After being smoked in the ISO mode, the Cambridge filter pad was used to collect mainstream cigarette smoke, and then extracted by 40 mL cyclohexane containing deuterated benzo [a] pyrene as the internal standard. The extract was cleaned-up by an automated PrepLinc SPE-AccuVap system and then detected using GC-MS/MS. The detection limits for benzo [a] pyrene, benzo [a] anthracene and chrysene were 0.05,0. 16, and 0.23 ng/cig, respectively. The recoveries were ranged from 91.5% to 102.1% to 102.1% with the relative standard deviations (RSDs) less than 5%. This method was proved to be simple, sensitive, and suitable for the determination of benzo [a] pyrene, benzo[a] anthracene and chrysene in mainstream cigarette smoke.