• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Facile detection of pesticides using atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry with multi-walled carbon nanotubes-based matrix

    2023-03-14 06:52:52SijinChenHunxiZhoLiliJioZhenhunWngMengyZhoLuTinYngXiuShuyingLiu
    Chinese Chemical Letters 2023年1期

    Sijin Chen,Hunxi Zho,Lili Jio,Zhenhun Wng,Mengy Zho,Lu Tin,Yng Xiu,*,Shuying Liu,b,*

    a Jilin Ginseng Academy,Changchun University of Chinese Medicine,Changchun 130117,China

    b Changchun Institute of Applied Chemistry,Chinese Academy of Science,Changchun 130022,China

    Keywords:Atmospheric pressure MALDI Pesticides MWCNTs-based matrix Ambient ionization

    ABSTRACT A novel atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry (AP-MALDIMS) method was established for the facile detection of pesticides in ambient environment.Four kinds of multi-walled carbon nanotubes (MWCNTs)-based matrix were synthesized and utilized to enhance the ionization efficiency of pesticides.Organophosphorus,anilinopyrimidine,carbamate,triazine,triazole and benzimidazole pesticides were directly desorbed and ionized from MWCNTs-based matrix in ambient environment,showing clear background and good sensitivity.In a comparison,Fe3O4-doped MWCNTs improved the intensity of pesticide ions more than the other three matrices.Moreover,MWCNTs-based matrix exhibited better performance than organic matrix.Quantitative analysis of pesticides using APMALDI-MS was validated to be adequate linearity,repeatability and sensitivity.Overall,AP-MALDI-MS combined with MWCNTs-based matrix enables the directly qualitative and quantitative analysis of pesticides in ambient environment.

    Pesticide refers to a general term for a wide variety of products designed to control and manage pests.It could be classified as insecticides,herbicides,fungicides and algicides,according to its primary target that intended to disrupt [1].Pesticide plays an important role in agricultural production for increasing the yield and value of agricultural products [2].However,the biological effects that make pest control products valuable may also result in unwanted effects that pose threats to human and environmental health.For this reason,there is demand for analytical techniques which are able to determine as many kinds of pesticides as possible with high sensitivity and throughput.Most of the methods proposed for the determination of pesticides use gas chromatography (GC) and liquid chromatography (LC) coupled with triple quadrupole mass spectrometry (MS) [3–6].Due to their high cost and complex analysis process,the application of these methods is limited.Nevertheless,MS is preferred as a time-saving and laborsaving approach [7].

    Atmospheric pressure matrix-assisted laser desorption ionization (AP-MALDI) is an ambient ionization method,introduced for the analysis of volatile molecules as a possible alternative to the ionization technique under reduced pressure [8].Its combination with MS not only enables the direct study of peptides [9–11],oligosaccharides [12,13] and bacterial identification [14],but also is capable of performing imaging experiments [15–17].However,APMALDI suffers from matrix problem in analysis of small molecules.Conventional organic matrix used in MALDI,such asα-cyano-4–hydroxy-cinnamic acid (CHCA),provides proton to the analyte for ionization through their cocrystallization [18].The interference in the low mass region and detector saturation are inevitable,which hinders the accurate analysis of small molecules.Much effort has been devoted to resolve this problem.Yang introduced magnetic silica nanoparticles as matrix for the analysis of oligosaccharides,amino,peptides,nucleosides,and ginsenosides.This nanoparticlebased matrix has better surface homogeneity,salt tolerance,and signal to noise (S/N) than conventional organic matrices,resulting in a good performance in the analysis of biomolecules [19].Hani analyzed biomolecules through desorption and ionization on graphene-coated silica,which reduced the chemical background significantly [20].

    Multi-walled carbon nanotubes (MWCNTs) have been developed as the matrix for MALDI MS analysis of small molecules [21].As MWCNTs do not readily ionize under moderate laser energy,it succeeds in eliminating ion interference and offers a clear background.But,because of its poor dispersion in water and organic solvent,MWCNTs was hard to be attached tightly to the sample target and hence to form homogeneous matrix layer,which lead to the reduced repeatability and resolution of MALDI MS analysis [22].In addition,the loosely attached MWCNTs tended to fly into the ion source,also raising a contamination problem.Therefore,MWCNTs was further functionalized to overcome these disadvantages [23–25].The functionalization procedure increased the solubility of MWCNTs in water by introducing carboxylic groups on its structure and cutting it into shortened tubes.Compared with raw MWCNTs,functionalized MWCNTs provide a homogenous and steady matrix layer,which makes them alternative matrices for MALDI-TOF MS analysis [26–28].For example,the Cd2+-doped carbon nanotubes with CdS nanoparticles could be used as matrix to efficiently ionize and analyze the microwave enzymatic digestion product of peptide mixtures and proteins [29].Polystyrene/oxidized carbon nanotubes film also showed good stability as sorbent and matrix to analyze small molecular compounds in urine samples [30].However,there is little research on the application of functionalized MWCNTs as the matrix of AP-MALDI-MS for the analysis of small molecules.AP-MALDI employs much lower laser energy and generates much shorter mean free path of ions in ambient environment than those of MALDI in closed circumstance and/or reduced pressure [31].Although they have been reported as the alternative matrices of MALDI MS,the feasibility and performance of functionalized MWCNTs used as AP-MALDI matrix are lack of comprehensive study,especially on the analysis of pesticides in ambient environment.

    In this contribution,AP-MALDI-MS combined with functionalized MWCNTs-based matrix was utilized to detect nine pesticides of six classes in ambient environment (Table S1 in Supporting information).Three kinds of functionalized MWCNTs,that is Fe3O4-doped (Fe-),oxidized (o-),andβ-cyclodextrin-coated (β-) MWCNTs,were synthesized and used as matrix together with intrinsic (in-) MWCNTs to enhance the efficiency and repeatability of the ambient ionization.Organic matrices were employed to compare and evaluate the performance of MWCNTs-based matrix.Under optimized conditions,the quantitation of pesticides was also performed and validated.The present work aims to study the feasibility of AP-MALDI-MS for the detection of small molecules,and to raise the possibility of directly qualitative and quantitative analysis of pesticides in ambient environment.

    The prepared in-MWCNTs,Fe-MWCNTs,o-MWCNTs andβ-MWCNTs are characterized by FTIR spectroscopy.As shown in Fig.S1a (Supporting information),there appear characteristic adsorption bands of in-MWCNTs at 3455 cm-1,1595 cm-1,1447 cm-1,1091 cm-1and 780 cm-1,which are assignable to the stretching vibrations of O-H and C=O bonds,asymmetric in-plane bending vibrations of C-H bond,stretching vibrations of C-O bond in tertiary alcohol group,and out-of-plane bending vibrations of C-H bond in aldehyde group,respectively.The bands at 2916 cm-1and 2851 cm-1are associated with C-H asymmetric and symmetric stretching vibrations of methylene group,respectively [32].The bands at 2409 cm-1and 2257 cm-1are resulted from unsaturated bonds.Because of the presence of functional groups,disordered or defect regions are supposed to be present in the in-MWCNTs.In Fig.S1b (Supporting information),the characteristic MWCNTs bands are observed with the appearance of a new band at 610 cm-1,which is assignable to the Fe-O out-of-plane bending vibrations,indicating that oxidized ferric species is introduced into MWCNTs framework with its integrity being maintained [33].The slight decrease of the 3455 cm-1band is attributed to the neutralization reaction after the addition of NaOH.For o-MWCNTs,the stretching vibration band of O-H at 3455 cm-1is enhanced with the appearance of two bands at 1249 cm-1and 1084 cm-1,which are associated with C-O-C asymmetric and symmetric stretching vibrations in ester group,confirming the successful oxidation of MWCNTs [34].Excessiveβ-cyclodextrin is mixed with MWCNTs to prepareβ-MWCNTs.Therefore,the spectrum of the resultingβ-MWCNTs is dominated by the characteristic adsorption bands ofβcyclodextrin,such as the asymmetric and symmetric stretching vibration of C-O bond in ether group at 1157 cm-1and 1034 cm-1,respectively,as well as the characteristic bands ofα-(1,4) glucopyranose between 1000 cm-1to 500 cm-1[35].

    Fig.1.X-ray diffraction patterns of in-MWCNTs (a),Fe-MWCNTs (b),o-MWCNTs (c)and β-MWCNTs (d).

    The X-ray diffraction patterns of in-MWCNTs,Fe-MWCNTs,o-MWCNTs andβ-MWCNTs are presented in Fig.1.These matrices show two broad diffraction peaks centered at 25.77° and 42.66°,which are in good agreement with the standard data of MWCNTs[32].In the pattern of Fe-MWCNTs,the peaks at 31.78°,45.54° and 56.67° are indicative of the presence of crystallized Fe3O4in Fe-MWCNTs (JCPDS No.21–0920).The pattern of o-MWCNTs is similar to that of in-MWCNTs,suggesting the oxidation treatment has little effect on the crystallinity of MWCNTs,but to introduce the oxygen-containing functional groups.These functional groups are beneficial to the dispersion of MWCNTs in methanol/water solvent which could increase the adhesion of MWCNTs to sample target so as to improve the repeatability and stability of AP-MALDI-MS analysis.Forβ-MWCNTs,its pattern is dominated by the diffraction peaks ofβ-cyclodextrin at 12.51°,18.46° and 26.40° with poor crystallization (JCPDS No.32–1627),which is similar to the FTIR results.

    Laser energy has the direct impact on the ionization efficiency and hence the ion signal intensity of AP-MALDI-MS.In this work,the maximum pulse energy of the employed solid-state laser was 3 μJ,which is much lower than that of MALDI ion source [31].It was adjusted to determine the optimal energy for the ionization of pesticides.Typically,methomyl,cyprodinil,metolcarb and atrazine were analyzed using Fe-MWCNTs as matrix.And the absolute intensities of their protonated ion in base peak were recorded as a function of laser energy between 10% and 70% of the maximum energy with a stepwise of 10%.As shown in Fig.S2 (Supporting information),the pesticides could be ionized once the laser energy is over the threshold of 30%,showing a less reliance of MWCNTsbased matrix on optimal laser properties.The absolute intensities of monitored ions increase with laser energy,since higher incident laser energy could provide more energy to facilitate desorption and ionization of the analytes from matrix.When the laser energy is over 60%,the absolute intensities tend to be steady.Taking into account the energy attenuation of the laser devise when working at a constant high energy level,60% of the maximum energy is selected in further detection.Moreover,it is noted that,under the same conditions,the absolute intensities of these four pesticide ions exhibit different increase rate with incident laser energy,suggesting that the structure of analyte plays a key role in laser energy absorption and analyte desorption and ionization.

    Fig.2.The mass spectra of cyprodinil analyzed by AP-MALDI-MS using in-MWCNTs (a),Fe-MWCNTs (b),o-MWCNTs (c) and β-MWCNTs (d) as matrix,respectively.

    The sample preparation method decides the mixing of analyte and matrix,which has effect on the transfer of incident laser energy from matrix to analyte through the formation of co-crystalline or layered microstallites.Using Fe-MWCNTs as matrix,four sample preparation methods were evaluated for their effects on the absolute peak intensity of protonated pesticide ions.(1) Dried droplet method: the mixture of analyte solution and matrix in a certain mixing ratio was deposited onto the AP-MALDI target and left to air dry.(2) Thin layer method: a uniformly distributed thin layer of matrix was prepared with the assistance of gentle heating on top of which the analyte solution was deposited in a second step.(3) Sandwich method: another layer of matrix was deposited on top of a pre-deposited bilayered sample prepared by thin layer method.(4) Sample first method: Analyte solution was deposited onto the target and left to dry in air.Then,matrix was deposited onto the first layer.As shown in Fig.S3 (Supporting information),the dried droplet method exhibits the lowest signal intensity of pesticides.This is because the co-crystallization of matrix and analyte tended to yield comparatively large and unevenly distributed crystals,which were detrimental for the repeatability of MS detection.In contrast,the other three methods offered at least one interface between matrix and analyteviasuccessive deposition.The sandwich and the sample first method covered a matrix layer on top of the pesticide layer.As MWCNTs has marked adsorption to pesticides,the covered matrix layer may be unfavorable to the formation and desorption of pesticide ions from microstallites to gas phase,resulting in the relatively lower signal intensity.On the contrary,the thin layer method exposed pesticides to the direct laser irradiation.It is superior to the other three methods on the signal intensity of pesticides and therefore is used for the sample preparation in further AP-MALDI analysis.

    Upon laser irradiation,the matrix in AP-MALDI functions as a mediator for laser energy absorption and transfer to assist the ionization of analyte molecules,which may also raise potential matrix effect to interfere MS analysis.The effect of MWCNTs-based matrix on the ionization of pesticides was typically evaluated using cyprodinil,one of anilinopyrimidine fungicides.As shown in Fig.2,each matrix demonstrates relatively clean spectrum with strong base peak centered atm/z226.3 and good S/N ratio.There are none of other addut,fragment,or matrix ions except for the protonated ion of cyprodinil.No distinctive difference in the four matrices is observed in these spectra.As a comparison,cyprodinil solution was directly deposited on the bare sample target and was irradiated by laser without matrix assisted.No peaks atm/z226.3 are observed,while the peaks atm/z279.2 and 304.3 are originated from sample target,as shown in the corresponding insets of Fig.2.This observation indicates that MWCNTs-based matrix are effective and essential in the direct detection of cyprodinil by AP MALDI.

    To further confirm the possibility of MWCNTs-based matrix to assist the desorption and ionization of pesticides under atmospheric pressure by laser irradiation,another eight pesticides of six classes,including organophosphorus,carbamate,triazine,triazole and benzimidazole are analyzed by AP-MALDI with the use of in-MWCNTs,Fe-MWCNTs,o-MWCNTs andβ-MWCNTs as matrix.As shown in Figs.S4-S11 (Supporting information),all the pesticides could be ionized and detected by AP-MALDI using MWCNTsbased matrix in positive ion mode.The intact pesticide molecules are preserved in adduct ions without decomposition owing to the collisional cooling of the expanding plume,which suggests the soft ionization characteristics.Most of the detected pesticide ions are in their protonated form with some exceptions.The [M+H]+,[M+Na]+,and [M+K]+ions of dimethoate and methomyl are simultaneously detected when using in-MWCNTs as matrix (Figs.S5a and S7a in Supporting information),while only the [M+K]+ions are obtained for carbendazim in all the matrices (Fig.S6 in Supporting information).The ionization efficiency varies with pesticides and matrices.For example,cyprodinil and atrazine exhibit high ionization efficiency and low background signals with no interference to the analytes (Fig.2 and Fig.S4 in Supporting information).Triadimenol and diniconazole undergo relatively low efficient ionization process,resulting in abundant background interference(Figs.S8 and S10 in Supporting information).

    Although the ambient enviroment of AP-MALDI inevitably brings background interference from atmosphere and sample target under high laser energy,using appropriate matrix could reduce the interference by improving the ionization efficiency of analytes.The four kinds of MWCNTs-based matrix exhibited different performance of assisted ionization for pesticides.The prepared Fe-MWCNTs,o-MWCNTs andβ-MWCNTs give relatively higher S/N ratios than in-MWCNTs when detecting metolcarb and diniconazole (Figs.S9 and S10 in Supporting information).On the other hand,in-MWCNTs shows a more clear spectrum than the other three matrices in the analysis of methomyl (Fig.S7 in Supportinginformation).As shown in Fig.3,Fe-MWCNTs improves the intensity of most pesticide ions more than the other three matrices.In combination with the S/N ratios as labeled in the corresponding mass spectra (Fig.2 and Figs.S4-S11 in Supporting information),MWCNTs-based matrix is suitable for the analysis of the nine pesticides.Moreover,the functionalization of MWCNTs could enhance the production of pesticide ions by AP-MALDI.And Fe-MWCNTs is superior to the other matrices in the detection of most of the nine pesticide ions.The introduction of Fe3O4particles into MWCNTs accounts for the results.

    Table 1 The calibration curve, R2,LOD,LOQ and linearity range of pesticides analyzed by AP-MALDI-MS using Fe-MWCNTs as matrix.

    Fig.3.Peak intensities of nine pesticides detected by AP-MALDI using four kinds of MWCNTs-based matrix.

    CHCA and THAP are two typical organic matrices with molecular weight of 189.2 and 168.2,respectively.They were employed to detect pesticides by using AP-MALDI-MS.As shown in Fig.S12 (Supporting information),cyprodinil and atrazine are ionized,showing the base peak atm/z226.3 andm/z216.1 of their respective [M+H]+ion and abundant interfering peaks.For other pesticides discussed above,there are no adduct ions present except for the [M+H]+ions when employing CHCA and THAP as matrix,indicating good protonating effect of CHCA and THAP on pesticides.This is attributed to their aromatic core and conjugated structures which are advantageous to the laser energy uptake and the resulting electronic excitation of the matrix.Moreover,CHCA and THAP do not give rise to obvious signals originating from thequasi-molecular ions of their own,which is due to the radiolytic decomposition of organic matrix under high laser fluence.However,the minor intensity of target pesticide ions and high level of background ions lead to the lower S/N ratios in comparison with those of MWCTNs-based matrix.This could be rationalized on the basis of detector saturation resulting from the series of cluster ions and some more abundant fragment ions of the largely used organic matrix [36].By contrast,MWCNTs-based matrix is more stable towards laser irradiation in ambient environment and has appropriate energy levels for the laser energy transfer to boost desorption and ionization of low molecular weight pesticides.Therefore,MWCNTs-based matrix is superior to the organic matrix in the facile detection of pesticides using AP-MALDI-MS.

    The accuracy of ambient ionization in quantification is deeply affected by the measurement repeatability.Therefore,before developing quantitative method,the intra- and inter-spot repeatability of AP-MALDI-MS on the analysis of nine pesticides was investigated using MWCNTs-based matrix.As shown in Table S2 (Supporting information),the repeatability varies significantly with matrices and pesticides.The intra-spot repeatability ranges from 4.41%to 8.23%,while the inter-spot repeatability ranges from 2.81% to 29.34%.When using Fe-MWCNTs and o-MWCNTs as matrix,the repeatability is acceptable with RSDs less than 8.16% and 13.15%for intra- and inter-spot,respectively.This is due to their homogeneous dispersion in solvent and enhanced ionization efficiency to pesticides.As for CHCA and THAP,the intra- and inter-spot repeatability is unsatisfactory with RSDs over than 6.61% and 11.83%,which are higher than that of Fe-MWCNTs and o-MWCNTs for each pesticide and not suitable for the quantification of pesticides using AP-MALDI.Therefore,calibration curves for nine pesticides were obtained using Fe-MWCNTs and o-MWCNTs as matrix on APMALDI-MS.As shown in Table 1 and Table S3 (Supporting information),the correlation coefficient (R2) of each pesticide is above 0.99,indicating a good linearity between the concentration and MS peak intensity.The linearity could be remained in the range of 3.0–300.0 μg/mL.Based on the slopes of the calibration curves,diniconazole exhibits the lowest sensitivity,which is owing to its low ionization efficiency in both of Fe-MWCNTs and o-MWCNTs as discussed above.The LOD and LOQ are below 0.9 μg/mL and 3.0 μg/mL,respectively.Thus,it is possible for AP-MALDI-MS to quantify pesticides by using Fe-MWCNTs and o-MWCNTs as matrix.

    In this study,we proposed an AP-MALDI-MS method for the facile detection of pesticides.Four kinds of MWCNTs-based materials were employed as matrices.As a proof of concept,the nine pesticides of six classes were successfully detected in ambient environment.MWCNTs-based matrix enables AP-MALDI to detect small molecule compoundsviasoft ionization with no decomposition of the pesticides during ionization.In comparison with organic matrix,MWCNTs-based matrix alleviates the background signals and improves the efficiency of desorption/ionization process.Additionally,MWCNTs-based matrix is simple in preparation.Among the employed matrix,Fe-MWCNTs shows the best performance in the assistance of pesticide ionization.Moreover,the quantitative method of pesticides based on AP-MALDI-MS was validated to be good linearity and repeatability when using Fe-MWCNTs and o-MWCNTs as matrix.In comparison with LC MS and GC MS,the developed method simplifies the sample introduction from the autosampler injections to the direct high-density spotting of pesticides on sample target in parallel and gets rid of the time-consuming chromatographic separation stage by using highfrequency lasers for sampling,which takes no more than a few minutes.It can be also used to detect polar,thermally unstable or low volatility pesticides that are not suitable for GC–MS analysis.Overall,AP-MALDI-MS combined with MWCNTs-based matrix has simple introduction and facile detection of the pesticides,and is of great potential for real-time monitoring and facile detection of pesticides in food and traditional Chinese medicine samples,that is what our lab is studying.

    Declaration of competing interest

    The authors declare no conflict of interest.

    Acknowledgments

    The authors thank Dr.Chunsheng Liu of the ASPEC Technologies (Beijing) Limited for providing the AP-MALDI UHR ion source.This work was financially supported by the Science and Technology Development Plan Project of Jilin Province (Nos.20210204098YY,20200201093JC).

    Supplementary materials

    Supplementary material associated with this article can be found,in the online version,at doi:10.1016/j.cclet.2022.03.009.

    特大巨黑吊av在线直播| 久久婷婷青草| 亚洲国产精品一区三区| 亚洲色图 男人天堂 中文字幕 | 午夜福利视频在线观看免费| 大又大粗又爽又黄少妇毛片口| 黄色欧美视频在线观看| 亚洲少妇的诱惑av| 欧美日韩一区二区视频在线观看视频在线| 久久99精品国语久久久| 菩萨蛮人人尽说江南好唐韦庄| 男女高潮啪啪啪动态图| 国产成人av激情在线播放 | 日韩一区二区三区影片| 日韩 亚洲 欧美在线| 老司机亚洲免费影院| 水蜜桃什么品种好| 中文字幕久久专区| 女人久久www免费人成看片| 国产精品一国产av| 免费观看无遮挡的男女| 在线 av 中文字幕| 欧美3d第一页| 免费看光身美女| 狠狠婷婷综合久久久久久88av| 大香蕉久久成人网| 日韩不卡一区二区三区视频在线| 成人毛片a级毛片在线播放| av在线观看视频网站免费| av有码第一页| 日本-黄色视频高清免费观看| 国产黄色免费在线视频| 精品久久久久久久久亚洲| 成人国产av品久久久| 久久精品国产亚洲av涩爱| 在线看a的网站| 99久久中文字幕三级久久日本| 91精品伊人久久大香线蕉| 晚上一个人看的免费电影| 亚洲在久久综合| 国产午夜精品久久久久久一区二区三区| 制服人妻中文乱码| 欧美日韩亚洲高清精品| 国产精品一区二区在线观看99| 久久久久精品久久久久真实原创| 日韩欧美精品免费久久| 黑人巨大精品欧美一区二区蜜桃 | 成人国产麻豆网| 久久 成人 亚洲| 狠狠精品人妻久久久久久综合| 久久久久国产网址| 日本vs欧美在线观看视频| 美女内射精品一级片tv| 精品久久久噜噜| 亚洲国产精品一区二区三区在线| 亚洲综合色网址| 女性被躁到高潮视频| 大又大粗又爽又黄少妇毛片口| 国产免费一级a男人的天堂| 亚洲综合色网址| 美女国产高潮福利片在线看| 18+在线观看网站| freevideosex欧美| 日韩成人av中文字幕在线观看| 超碰97精品在线观看| 欧美+日韩+精品| 亚洲色图 男人天堂 中文字幕 | 国产亚洲精品久久久com| 少妇精品久久久久久久| 亚洲一区二区三区欧美精品| 青青草视频在线视频观看| 国产无遮挡羞羞视频在线观看| 国产成人一区二区在线| 视频区图区小说| 国产精品久久久久久av不卡| 亚洲国产毛片av蜜桃av| 亚洲精品乱码久久久久久按摩| 日韩强制内射视频| 久久久久久久大尺度免费视频| 国产成人精品福利久久| 亚州av有码| 日本欧美国产在线视频| 国产午夜精品一二区理论片| 黄片无遮挡物在线观看| 午夜激情久久久久久久| 99久国产av精品国产电影| 青春草视频在线免费观看| 我的老师免费观看完整版| 日本猛色少妇xxxxx猛交久久| 曰老女人黄片| 日韩在线高清观看一区二区三区| 免费播放大片免费观看视频在线观看| 国产亚洲精品久久久com| 国产淫语在线视频| 国产精品偷伦视频观看了| 中文字幕最新亚洲高清| 成年人午夜在线观看视频| 国产爽快片一区二区三区| h视频一区二区三区| 亚洲,欧美,日韩| 观看av在线不卡| 国产精品久久久久久av不卡| 久久婷婷青草| 精品久久久久久久久亚洲| 国产精品久久久久久av不卡| 午夜影院在线不卡| 亚洲精品,欧美精品| 日本爱情动作片www.在线观看| 在线亚洲精品国产二区图片欧美 | a级毛片黄视频| 少妇被粗大的猛进出69影院 | 一级毛片 在线播放| 久久国内精品自在自线图片| 大又大粗又爽又黄少妇毛片口| 久久免费观看电影| 免费观看无遮挡的男女| 美女中出高潮动态图| 日韩一本色道免费dvd| 国产精品女同一区二区软件| 伊人久久国产一区二区| 91久久精品电影网| 最近中文字幕高清免费大全6| 国产在线一区二区三区精| 中文字幕人妻丝袜制服| 成人漫画全彩无遮挡| 午夜精品国产一区二区电影| 免费观看av网站的网址| 久久人人爽av亚洲精品天堂| 丝袜喷水一区| 我的老师免费观看完整版| 亚洲精品国产色婷婷电影| 久久精品国产亚洲网站| 免费av不卡在线播放| 五月玫瑰六月丁香| 亚洲精品456在线播放app| 国产精品.久久久| 我的女老师完整版在线观看| 青春草国产在线视频| 成年人免费黄色播放视频| 精品一区二区免费观看| 成年人午夜在线观看视频| 少妇精品久久久久久久| 99国产综合亚洲精品| 精品久久久久久电影网| 国产免费视频播放在线视频| 欧美xxxx性猛交bbbb| 国产亚洲精品第一综合不卡 | 一本一本久久a久久精品综合妖精 国产伦在线观看视频一区 | av免费观看日本| 欧美少妇被猛烈插入视频| 午夜91福利影院| 国产精品久久久久久久久免| 人妻 亚洲 视频| 男女免费视频国产| 免费大片18禁| 欧美一级a爱片免费观看看| 超色免费av| 亚洲欧美日韩卡通动漫| 欧美精品高潮呻吟av久久| 男女边摸边吃奶| 精品少妇久久久久久888优播| av线在线观看网站| 久久久午夜欧美精品| 精品一区在线观看国产| 亚洲av免费高清在线观看| 狠狠精品人妻久久久久久综合| 久久av网站| 满18在线观看网站| 精品久久久久久电影网| 免费观看无遮挡的男女| 天堂俺去俺来也www色官网| kizo精华| 日韩av在线免费看完整版不卡| 国产黄片视频在线免费观看| 日韩一区二区视频免费看| 亚洲熟女精品中文字幕| 黄色视频在线播放观看不卡| 亚洲国产日韩一区二区| 久久久精品94久久精品| 亚洲少妇的诱惑av| 欧美日韩视频精品一区| 我要看黄色一级片免费的| 80岁老熟妇乱子伦牲交| 久久久久久伊人网av| 最近2019中文字幕mv第一页| 美女脱内裤让男人舔精品视频| 午夜久久久在线观看| 日韩 亚洲 欧美在线| 亚洲国产毛片av蜜桃av| 久久精品国产自在天天线| 久久人人爽av亚洲精品天堂| 在线亚洲精品国产二区图片欧美 | 欧美3d第一页| 久久热精品热| 亚洲欧美清纯卡通| 少妇高潮的动态图| 中国国产av一级| 国产乱人偷精品视频| 日韩人妻高清精品专区| 美女内射精品一级片tv| 在线精品无人区一区二区三| 亚洲欧洲日产国产| 老女人水多毛片| 大香蕉久久成人网| 久久国内精品自在自线图片| 国产白丝娇喘喷水9色精品| 一级a做视频免费观看| 久久久久久久国产电影| 免费人妻精品一区二区三区视频| av女优亚洲男人天堂| 亚洲精品美女久久av网站| 中文精品一卡2卡3卡4更新| 如何舔出高潮| 这个男人来自地球电影免费观看 | av线在线观看网站| freevideosex欧美| 久久97久久精品| 久久国内精品自在自线图片| 十分钟在线观看高清视频www| 91午夜精品亚洲一区二区三区| 国产一区二区在线观看日韩| 亚洲国产精品一区三区| 成人无遮挡网站| 成人二区视频| 美女中出高潮动态图| 99精国产麻豆久久婷婷| 少妇被粗大猛烈的视频| 久久久久人妻精品一区果冻| 高清欧美精品videossex| 少妇精品久久久久久久| videosex国产| 人人妻人人澡人人看| 少妇猛男粗大的猛烈进出视频| 精品99又大又爽又粗少妇毛片| 熟女av电影| 日本av免费视频播放| 精品一区在线观看国产| 久久久久久久久久久丰满| 亚洲激情五月婷婷啪啪| 亚洲欧美清纯卡通| 黄色一级大片看看| 黑人欧美特级aaaaaa片| 久久久精品免费免费高清| 最黄视频免费看| 欧美日韩av久久| 夫妻性生交免费视频一级片| 91在线精品国自产拍蜜月| 久久狼人影院| 免费播放大片免费观看视频在线观看| 建设人人有责人人尽责人人享有的| 在线天堂最新版资源| 在线观看美女被高潮喷水网站| 免费少妇av软件| 美女主播在线视频| 亚洲精品成人av观看孕妇| 国产av码专区亚洲av| 精品视频人人做人人爽| 欧美亚洲 丝袜 人妻 在线| 性色avwww在线观看| 熟女av电影| 啦啦啦在线观看免费高清www| 丰满饥渴人妻一区二区三| 成人免费观看视频高清| 青春草亚洲视频在线观看| av在线老鸭窝| 极品人妻少妇av视频| 久久99热6这里只有精品| 成年美女黄网站色视频大全免费 | 成年人免费黄色播放视频| 亚洲国产精品专区欧美| 亚洲国产欧美日韩在线播放| 亚洲精品乱码久久久久久按摩| 欧美日韩国产mv在线观看视频| 精品少妇黑人巨大在线播放| 久久ye,这里只有精品| tube8黄色片| 欧美日韩成人在线一区二区| xxxhd国产人妻xxx| 97在线人人人人妻| 国产精品 国内视频| 校园人妻丝袜中文字幕| 国产淫语在线视频| 免费人妻精品一区二区三区视频| 国产精品久久久久成人av| 免费大片黄手机在线观看| 男女高潮啪啪啪动态图| 日韩欧美一区视频在线观看| 国产成人免费观看mmmm| 纯流量卡能插随身wifi吗| 免费人妻精品一区二区三区视频| av女优亚洲男人天堂| 色网站视频免费| 久久97久久精品| 久久av网站| 色吧在线观看| 国产乱人偷精品视频| 午夜av观看不卡| 国产黄色视频一区二区在线观看| 满18在线观看网站| 美女cb高潮喷水在线观看| 大香蕉久久网| 啦啦啦中文免费视频观看日本| 少妇被粗大的猛进出69影院 | 国国产精品蜜臀av免费| 亚洲精品乱码久久久v下载方式| 18在线观看网站| 亚洲精品日本国产第一区| 波野结衣二区三区在线| 在线观看免费高清a一片| 国产毛片在线视频| 亚洲av电影在线观看一区二区三区| 国产色婷婷99| 波野结衣二区三区在线| 美女xxoo啪啪120秒动态图| 一级毛片aaaaaa免费看小| 桃花免费在线播放| av黄色大香蕉| 菩萨蛮人人尽说江南好唐韦庄| 最近2019中文字幕mv第一页| www.av在线官网国产| 青青草视频在线视频观看| 日韩电影二区| 国产精品 国内视频| √禁漫天堂资源中文www| 欧美 日韩 精品 国产| 免费观看av网站的网址| 日韩欧美精品免费久久| 国产男女超爽视频在线观看| 精品少妇内射三级| 在线播放无遮挡| 亚洲精品乱久久久久久| 亚洲国产毛片av蜜桃av| 日韩大片免费观看网站| 午夜影院在线不卡| 大码成人一级视频| 免费少妇av软件| 成人国语在线视频| 91成人精品电影| 精品国产一区二区久久| 蜜桃久久精品国产亚洲av| 日本色播在线视频| 亚洲国产欧美日韩在线播放| 26uuu在线亚洲综合色| 欧美3d第一页| 国产精品无大码| 韩国av在线不卡| 视频在线观看一区二区三区| 亚洲五月色婷婷综合| 天天操日日干夜夜撸| 亚洲四区av| 欧美日韩综合久久久久久| 久久 成人 亚洲| 国产成人freesex在线| 丰满迷人的少妇在线观看| 欧美变态另类bdsm刘玥| 亚洲av.av天堂| 婷婷色av中文字幕| 成人黄色视频免费在线看| 久久99热6这里只有精品| 超色免费av| 在线免费观看不下载黄p国产| 边亲边吃奶的免费视频| 狂野欧美激情性bbbbbb| 国产精品不卡视频一区二区| 日产精品乱码卡一卡2卡三| 最近中文字幕高清免费大全6| av黄色大香蕉| 亚洲av欧美aⅴ国产| 日本wwww免费看| 午夜福利影视在线免费观看| 亚洲国产毛片av蜜桃av| 91精品三级在线观看| 国产精品人妻久久久影院| 少妇熟女欧美另类| 大香蕉久久网| 免费不卡的大黄色大毛片视频在线观看| 亚洲欧美中文字幕日韩二区| 日韩成人伦理影院| 少妇人妻 视频| 国产精品嫩草影院av在线观看| 中国美白少妇内射xxxbb| 日本wwww免费看| 久久久久精品性色| 久久国产精品大桥未久av| 在线观看国产h片| 免费黄频网站在线观看国产| 亚洲国产av新网站| 精品亚洲成a人片在线观看| 中国三级夫妇交换| 国产淫语在线视频| 亚洲欧洲日产国产| 久久av网站| 久久久久久久精品精品| 国产在线免费精品| 好男人视频免费观看在线| 国产欧美亚洲国产| 又粗又硬又长又爽又黄的视频| 日本黄色片子视频| 在线看a的网站| 热99国产精品久久久久久7| 国产成人精品久久久久久| 2021少妇久久久久久久久久久| 中文字幕人妻丝袜制服| 久久久久网色| 91午夜精品亚洲一区二区三区| 秋霞在线观看毛片| 国产精品无大码| 特大巨黑吊av在线直播| 草草在线视频免费看| 亚洲图色成人| av免费在线看不卡| 成年女人在线观看亚洲视频| a级毛片免费高清观看在线播放| 少妇的逼水好多| 久久ye,这里只有精品| 人人妻人人爽人人添夜夜欢视频| av国产精品久久久久影院| 久久久久久久久久久免费av| 精品久久久精品久久久| 亚洲av日韩在线播放| 国产老妇伦熟女老妇高清| 中文天堂在线官网| 国产乱来视频区| 婷婷色麻豆天堂久久| 免费日韩欧美在线观看| 色94色欧美一区二区| 亚洲色图综合在线观看| 人人妻人人澡人人爽人人夜夜| 好男人视频免费观看在线| 色94色欧美一区二区| 免费观看无遮挡的男女| 日韩成人伦理影院| 男女高潮啪啪啪动态图| 一级毛片aaaaaa免费看小| 高清av免费在线| 两个人免费观看高清视频| 日韩强制内射视频| 国产成人freesex在线| 久久99热这里只频精品6学生| 18+在线观看网站| 日韩中文字幕视频在线看片| 99久久人妻综合| 黄片无遮挡物在线观看| 国产精品99久久99久久久不卡 | 午夜福利影视在线免费观看| 22中文网久久字幕| 国产精品熟女久久久久浪| 国产熟女欧美一区二区| 一本大道久久a久久精品| 午夜福利网站1000一区二区三区| 99热全是精品| 成人手机av| 久久精品夜色国产| 永久免费av网站大全| 一本一本综合久久| 人体艺术视频欧美日本| 免费久久久久久久精品成人欧美视频 | 少妇猛男粗大的猛烈进出视频| 伊人久久精品亚洲午夜| 免费大片18禁| 国产成人午夜福利电影在线观看| 欧美精品国产亚洲| 国产一区有黄有色的免费视频| 久久久久精品久久久久真实原创| 久久久精品区二区三区| 久久久亚洲精品成人影院| 一区二区三区乱码不卡18| 久久精品国产亚洲av涩爱| 男女边吃奶边做爰视频| 菩萨蛮人人尽说江南好唐韦庄| 亚洲av不卡在线观看| 免费高清在线观看视频在线观看| 国产精品久久久久久精品电影小说| 人体艺术视频欧美日本| 好男人视频免费观看在线| 久久久久国产网址| 美女xxoo啪啪120秒动态图| 国产午夜精品一二区理论片| 日韩三级伦理在线观看| 精品99又大又爽又粗少妇毛片| 欧美日韩在线观看h| 国产日韩欧美视频二区| 亚洲精品aⅴ在线观看| 国产精品熟女久久久久浪| 精品国产露脸久久av麻豆| 热re99久久国产66热| 亚洲中文av在线| 一区二区三区四区激情视频| 伦理电影大哥的女人| 在现免费观看毛片| 欧美日韩在线观看h| 国产日韩欧美亚洲二区| 国产精品欧美亚洲77777| 色5月婷婷丁香| videossex国产| a级毛片在线看网站| 国产精品久久久久久精品古装| 亚洲国产av影院在线观看| 乱码一卡2卡4卡精品| 亚洲国产精品专区欧美| 中文字幕人妻熟人妻熟丝袜美| 少妇人妻久久综合中文| 午夜福利视频在线观看免费| 日韩中文字幕视频在线看片| 在线观看一区二区三区激情| 久久久久视频综合| 日日啪夜夜爽| 菩萨蛮人人尽说江南好唐韦庄| 亚洲国产精品国产精品| 色婷婷av一区二区三区视频| 国产精品一二三区在线看| 国产av码专区亚洲av| 久久国内精品自在自线图片| 亚洲美女黄色视频免费看| 亚洲精品一区蜜桃| 国产精品欧美亚洲77777| 大香蕉久久网| 欧美日韩av久久| 看非洲黑人一级黄片| 午夜影院在线不卡| 天美传媒精品一区二区| 男女免费视频国产| 超碰97精品在线观看| 国产成人免费观看mmmm| 中国美白少妇内射xxxbb| 一级毛片我不卡| 亚洲精品视频女| 久久精品国产a三级三级三级| 午夜久久久在线观看| 五月开心婷婷网| 午夜激情av网站| 亚洲欧洲国产日韩| av专区在线播放| 在线观看免费高清a一片| 日本免费在线观看一区| 久久久久网色| 精品国产露脸久久av麻豆| 大香蕉久久成人网| 热re99久久精品国产66热6| 69精品国产乱码久久久| 三上悠亚av全集在线观看| 日韩制服骚丝袜av| 高清毛片免费看| 最新中文字幕久久久久| 国产爽快片一区二区三区| 哪个播放器可以免费观看大片| 亚洲国产成人一精品久久久| 精品国产乱码久久久久久小说| 高清毛片免费看| 日日撸夜夜添| 夜夜爽夜夜爽视频| 大片电影免费在线观看免费| 日韩欧美一区视频在线观看| 久久久久人妻精品一区果冻| 伊人久久精品亚洲午夜| 嫩草影院入口| 国产av码专区亚洲av| a级毛片黄视频| 亚洲激情五月婷婷啪啪| 韩国高清视频一区二区三区| 国产午夜精品久久久久久一区二区三区| 热re99久久精品国产66热6| 精品国产乱码久久久久久小说| 日日啪夜夜爽| 在线观看三级黄色| 成年女人在线观看亚洲视频| 在线观看国产h片| 日本黄色日本黄色录像| 国产免费一区二区三区四区乱码| 一级毛片黄色毛片免费观看视频| 美女国产高潮福利片在线看| 亚洲精品日韩在线中文字幕| 亚洲精品中文字幕在线视频| 亚洲欧美成人综合另类久久久| 亚洲欧美色中文字幕在线| 一级毛片电影观看| 免费高清在线观看日韩| 啦啦啦啦在线视频资源| xxx大片免费视频| 女人久久www免费人成看片| 亚洲五月色婷婷综合| 免费不卡的大黄色大毛片视频在线观看| 日本黄色日本黄色录像| 国语对白做爰xxxⅹ性视频网站| 国产成人精品久久久久久| 一边摸一边做爽爽视频免费| 五月伊人婷婷丁香| 国产色爽女视频免费观看| 国产精品一区二区在线不卡| 高清午夜精品一区二区三区| 婷婷色av中文字幕| √禁漫天堂资源中文www| 99视频精品全部免费 在线| 91精品国产九色| 精品久久国产蜜桃| 波野结衣二区三区在线| 国产无遮挡羞羞视频在线观看| 自拍欧美九色日韩亚洲蝌蚪91| 成人亚洲精品一区在线观看| a级毛片黄视频| 一区在线观看完整版| 国产精品麻豆人妻色哟哟久久| 国国产精品蜜臀av免费| 十八禁网站网址无遮挡| 婷婷色综合www| 日产精品乱码卡一卡2卡三| 亚洲图色成人| 欧美国产精品一级二级三级| 九草在线视频观看| 国产片特级美女逼逼视频| 日本av免费视频播放| 在线观看人妻少妇| 久久午夜综合久久蜜桃| 久久国产精品大桥未久av| 51国产日韩欧美|