determination of multiple pesticides in fruits and vegetables using a modified quick, easy, cheap,...
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ARTICLE IN PRESSG ModelHROMA-355701; No. of Pages 11
Journal of Chromatography A, xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Journal of Chromatography A
j o ur na l ho me page: www.elsev ier .com/ locate /chroma
etermination of multiple pesticides in fruits and vegetables using aodified quick, easy, cheap, effective, rugged and safe method withagnetic nanoparticles and gas chromatography tandem mass
pectrometry
an-Fei Lia, Lu-Qin Qiaob,∗∗, Fang-Wei Lia, Yi Dinga, Zi-Jun Yanga, Ming-Lin Wanga,∗
College of Food Science and Engineering, Shandong Agricultural University, No. 61 Daizong Road, Tai’an, Shandong Province 271018, ChinaCollege of Plant Protection, Shandong Agricultural University, No. 61 Daizong Road, Tai’an, Shandong Province 271018, China
r t i c l e i n f o
rticle history:eceived 18 April 2014eceived in revised form 3 August 2014ccepted 4 August 2014vailable online xxx
eywords:uEChERSare magnetic nanoparticlesulti-residue analysis
lanar-ring pesticide
a b s t r a c t
Based on a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) sample preparation methodwith Fe3O4 magnetic nanoparticles (MNPs) as the adsorbing material and gas chromatography–tandemmass spectrometry (GC–MS/MS) determination in multiple reaction monitoring (MRM) mode, we estab-lished a new method for the determination of multiple pesticides in vegetables and fruits. It wasdetermined that bare MNPs have excellent function as adsorbent when purified, and it is better to beseparated from the extract. The amount of MNPs influenced the clean-up performance and recoveries. Toachieve the optimum performance of modified QuEChERS towards the target analytes, several parame-ters including the amount of the adsorbents and purification time were investigated. Under the optimumconditions, recoveries were evaluated in four representative matrices (tomato, cucumber, orange andapple) with the spiked concentrations of 10 �g kg−1, 50 �g kg−1and 200 �g kg−1 in all cases. The results
C–MS/MSruits and vegetables
showed that the recovery of 101 pesticides ranged between 71.5 and 111.7%, and the relative standarddeviation was less than 10.5%. The optimum clean-up system improved the purification efficiency andsimultaneously obtained satisfactory recoveries of multiple pesticides, including planar-ring pesticides.In short, the modified QuEChERS method in addition to MNPs used for removing impurities improvedthe speed of sample pre-treatment and exhibited an enhanced performance and purifying effect.
. Introduction
The detection of pesticide residues in conventional food hasmportant implications in the rational development and properse of chemical pesticides, protecting the environment and humanealth, and avoiding or reducing unnecessary loss of agriculture and
nternational trade disputes. In recent years, food safety and envi-onmental protection issues have attracted international attention.any countries in the world attach great importance to the issue
f pesticide residues and have imposed stringent limits on pesti-ide residues in agricultural products. For example, the European
Please cite this article in press as: Y.-F. Li, et al., Determination of mueasy, cheap, effective, rugged and safe method with magnetic nanopChromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.01
nion [1], Japan [2] and other countries or regions have set max-mum residue limit (MRLs) to improve the quality of importedgricultural products [3]. Increased pesticide residues have recently
∗ Corresponding author. Tel.: +86 0538 8249241; fax: +86 0538 8249157.∗∗ Corresponding author. Tel.: +86 0538 8249938; fax: +86 0538 8226399.
E-mail addresses: [email protected] (L.-Q. Qiao), [email protected]. Wang).
ttp://dx.doi.org/10.1016/j.chroma.2014.08.011021-9673/© 2014 Elsevier B.V. All rights reserved.
© 2014 Elsevier B.V. All rights reserved.
been detected in agricultural products whereas the requirementon monitoring pesticides is still at a low level. Therefore, a moreefficient, accurate and easier extraction and detection method isrequired imminently. Because multiple pesticides in fruits and veg-etables are at low concentrations, the separation and concentrationof the target analytes and the reduction or elimination of interfer-ence in samples has become one of the most critical steps in theentire analytical process.
Magnetic nanoparticles (MNPs), a novel and interesting mate-rial, have attracted enormous scientific attention in the past fewyears on account of their special magnetic, adsorption, optical,and mechanical properties and extremely large specific surfacearea. They have been applied in the fields of biomedicine, biotech-nology, material science, especially in analytical chemistry [4,5].Moreover, MNPs in combination with a sample preparation tech-nology, including QuEChERS [6,7], cloud point extraction (CPE)
ltiple pesticides in fruits and vegetables using a modified quick,articles and gas chromatography tandem mass spectrometry, J.1
[8] and molecular imprinting (MIP) [9,10], have been developed.Due to the unique magnetic of MNPs, they can easily be sepa-rated out of sample solution by an external magnetic field andavoid an additional step of centrifugation or filtration. Therefore,
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ARTICLEHROMA-355701; No. of Pages 11
Y.-F. Li et al. / J. Chrom
ample pre-treatment using MNPs can be simple and quick. Cur-ently, MNPs are coated with multiple functional layers to becomeunctionalised magnetic absorbents and have successfully beenpplied in the separation and enrichment of pesticides in differentamples. Wu’s group [11] synthesised a graphene-based magneticanocomposite as an effective adsorbent for the pre-concentrationf five carbamate pesticides in environmental water samples. Deng6] used multi-walled carbon-nanotube functionalised MNPs asorbents to analyse eight pesticide residues in tea samples. In theeported studies, MNPs were usually modified with a coating mate-ial to absorb the target analytes [4]. It is worth noting that usingare MNPs as adsorbents in pesticide residue analyses is still veryare in the literature. Furthermore, research on the function ofare MNPs in pesticide residue analysis has not been reported.heng’s group [7] reported using magnetic graphitised carbon blacknd primary secondary amine as sorbents with QuEChERS for thextraction of ten target pesticides in cucumber sample. In theiresearch, MNPs were not chemically modified for use in cleaninghe cucumber sample matrix. However, there is no comparison ofhe effect of adding MNPs or not in their work. Furthermore, noeport explicitly announced that bare MNPs can absorb impuritiesincluding pigments).
Currently, traditional and commonly used pesticide samplereparation technologies include solid-phase extraction (SPE) [12],olid phase micro extraction (SPME) [13–15], matrix solid-phaseispersion (MSPD) [16], gel permeation chromatography (GPC)17], molecular imprinting technology (MIP) [18], immune affinityhromatography (IAC) [19], microwave extraction (MAE) [20,21],ccelerated solvent extraction (ASE) [22], supercritical fluid extrac-ion (SFE) [23] and so on. However, these methods each have theirwn shortcomings, such as being time consuming and/or labourntensive, exposing workers to hazardous solvents, and for some ofhem it is difficult to easily and simultaneously achieve high qualityor the vast majority of pesticide extraction and analysis [24,25].
QuEChERS is a type of sample preparation method that wasrst reported by Anastassiades et al. in 2003 [26]. This method hasany advantages, including high recovery for a wide scope of pes-
icides with different polarity and volatility in different matrices,eeting low detection limits, use of smaller volumes of organic
olvents and simple operation [27–29]. Therefore, this method andodified versions of it are widely used in food analysis and serve
s a template for the determination of pesticide residues [30].he QuEChERS procedure involves an initial extraction with ace-onitrile followed by using anhydrous magnesium sulphate andodium chloride to stratify extract from water and dispersive-solidhase extraction (d-SPE) with anhydrous magnesium sulphate, pri-ary and secondary amine (PSA, used to remove sugar and fatty
cids) and/or in combination with C18 (used to dislodge non-polarnterferences) and graphitised carbon black (GCB, used to removeigments and steroids) sorbents for further clean-up [25]. Sometudies noted that GCB have excellent absorption of molecules withlanar structures, including pigments, steroids and structurallylanar pesticides [31–33]. Therefore, it is suitable for purifying aoloured sample matrix. However, increasing the amount of GCBill result in better purification efficiency and lower the recover-
es of structurally planar pesticides at the same time. In 2007, a.S. official method (AOAC 2007.01) [34] using a higher amount ofCB resulted in the loss of structurally planar pesticides. The Euro-ean Union in 2008 released its official analysis methods (EN15662)35] using lower amount GCB in the clean-up system that pre-ented the decreased recoveries of these pesticides using a moreomplex matrix than the AOAC method. Therefore, we decided to
Please cite this article in press as: Y.-F. Li, et al., Determination of mueasy, cheap, effective, rugged and safe method with magnetic nanopChromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.01
dd MNPs to the lower amount of GCB in the clean-up system toimultaneously obtain excellent purification effects and sat-sfactory results for multiple pesticides, including planar-ringesticides.
PRESS A xxx (2014) xxx–xxx
This work is the first attempt to use MNPs to analyse multiplepesticides in a food matrix. We emphasise the point that MNPs area novel and excellent absorbent material compared to traditionalmicro-sized adsorbents [5]. We also have modified QuEChERSmethodology and optimised the purification conditions by usingmixed cleaning agents and magnetic nanoparticles (Fe3O4). Com-pared to the research published by Zheng’s group [7], ourexperimental procedure has easier operation steps while reducingthe loss of the target. Therefore, the recovery rate was higher andbetter met the requirements for pesticides analysis. The methodexhibits greatly improved the purification efficiency, detectionspeed and sensitivity. The modified QuEChERS method with mag-netic nanoparticles in combination with gas chromatography andtandem mass spectrometry (GC–MS/MS) achieves satisfactoryresults in multiple pesticide analysis in fruits and vegetables.
2. Experimental
2.1. Materials
Materials. Ferric trichloride (FeCl3·6H2O) was obtained fromXilong Chemical Co., Ltd. (Guangdong, China). Ferrous chloride(FeCl2·4H2O) was purchased from Tianjin Damao Chemical ReagentFactory (Tianjin, China). NH3·H2O was purchased from BeijingChemical Works (Beijing, China). Acetonitrile was purchased fromTianjin Yongda Chemical Reagent Factory (Tianjin, China). Sodiumchloride (NaCl) and anhydrous magnesium sulphate (MgSO4) werepurchased from Tianjin Kaitong Chemical Reagent Factory (Tian-jin, China). PSA and GCB were purchased from Agela TechnologiesInc. The fruits and vegetables were obtained from a supermarket(Tai’an, China).
The standard solution of the pesticides in Table 1 was pro-vided by Dr. Ehrenstorfer GmbH (Augsburg, Germany). The workingstandard mixture containing 10 mg/L of each pesticide was pre-pared in methanol.
Apparatus. A centrifuge (TGL-16 table-top, high-speed refrig-erated centrifuge) from Xiangyi Centrifuge Instrument Co., Ltd.(Hunan, China) was used for precipitations. The homogeniser (T-18 Ultra Turrax Digital) was obtained from IKA Works Guangzhou(Guangzhou, China). The vortex shaker (QL-866) was obtainedfrom Qilinbeier Instrument Co., Ltd. (Jiangsu, China). The electronicscale (PB153-S) was obtained from Mettler-Toledo InstrumentCo., Ltd. (Greifensee, Switzerland). The grinder (SJ303-250) wasobtained from Supor Co., Ltd. (Zhejiang, China). The electromag-netic stirrer (78-1) was obtained from Ronghua Instrument Co.,Ltd. (Jiangsu, China). The constant temperature heating magneticstirrer (Hengyan-1) was obtained from Hengyan Instrument Co.,Ltd. (Zhengzhou, China). A vacuum oven (DZF-6020) from HasucInstrument Manufacture Co., Ltd. (Shanghai, China) was used todry Fe3O4.
2.2. Preparation of Fe3O4 magnetic nanoparticles
MNPs were obtained by a simple chemical co-precipitationmethod [36]. Briefly, FeCl3·6H2O (5.4110 g) and FeCl2·4H2O(1.9889 g) were dissolved in deionised water (100 mL) in a 250-ml round-bottom flask. 110 millilitres of ammonia were added tothe solvent drop-wise. After being vigorously stirred in an oil bathat 70 ◦C for 3 h, the MNPs were washed with deionised water fivetimes. Finally, it was washed with ethanol and dried in a vacuumdesiccator at 45 ◦C.
ltiple pesticides in fruits and vegetables using a modified quick,articles and gas chromatography tandem mass spectrometry, J.1
2.3. Sample preparation
A schematic representation of the modified sample preparationbased on the proposed QuEChERS method is shown in Fig. 1.
Please cite this article in press as: Y.-F. Li, et al., Determination of multiple pesticides in fruits and vegetables using a modified quick,easy, cheap, effective, rugged and safe method with magnetic nanoparticles and gas chromatography tandem mass spectrometry, J.Chromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.011
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Table 1Parameters of 101 pesticides determined by GC–MS/MS.
Peak No. Pesticides Retention time (min) Quantitation RM 1 CE (v) Identification RM 2 CE (v)
1 DBCP (Dibromo-3-chloropropane, 1,2-) 6.289 155 > 75 5 157 > 75 52 Naphthalene-d8 8.242 136.1 > 108.1 20 136.1 > 84.1 253 Dichlorvos 9.275 109 > 79 5 184.9 > 93 104 EPTC 11.366 128 > 86 5 132 > 90 55 Dichlormid 11.429 166 > 56.1 10 172.1 > 108.1 56 Dichloroaniline, 3,5- 12.484 161 > 99 20 161 > 90 207 Vernolate 13.178 128 > 86 0 161 > 160.1 58 Nitrapyrin 13.459 194 > 133 15 196 > 135 159 Propham 13.482 119 > 91 10 136.9 > 93 10
10 Etridiazole(Terrazole,Echlomezol) 13.486 211.1 > 183 10 183 > 140 1511 Phthalimide 13.943 147 > 103.1 5 104 > 76.1 1012 Acenaphthene 14.478 153.1 > 127 30 152.1 > 126 3013 Methacrifos 14.514 207.9 > 180.1 5 124.9 > 47.1 1014 Chloroneb 14.798 206 > 191.1 10 208 > 193.1 1015 XMC (3,5-Dimethylpheny N-Methyl Carbamate) 16.232 122 > 107.1 15 122 > 77 3016 Chlorfenprop-methyl 17.125 165 > 137.1 10 195.9 > 165.1 1017 Tecnazene (TCNB) 17.659 260.9 > 203 10 214.9 > 179 1018 Chlorethoxyfos 18.045 153 > 97 10 97 > 65 1519 Ethalfluralin 19.293 275.9 > 202.1 15 315.9 > 275.9 1020 Chlordimeform 19.295 151.9 > 117.1 10 195.9 > 181 521 Thiometon 21.310 125 > 47 15 125 > 79 1022 Schradan 22.219 153.1 > 46.1 15 199 > 92 523 Dimethipin 22.785 118 > 58 5 124 > 76 524 Sebuthylazine-desethyl 23.042 172 > 94 15 172 > 104 1525 BHC-gamma (Lindane, gamma HCH) 23.508 216.9 > 181 5 181 > 145 1526 Disulfoton 25.123 88 > 60 5 153 > 96.9 1027 Fluchloralin 25.273 325.8 > 62.9 15 306 > 263.9 1028 Tefluthrin, cis- 25.720 177.1 > 127.1 15 197 > 141.1 1029 Bromocyclen 26.535 271.8 > 236.9 15 236.9 > 118.9 3030 Monalide 27.009 127 > 65 25 85 > 57 031 Fenchlorphos oxon 27.313 268.9 > 254 15 270.9 > 256 1532 Parathion-methyl 28.888 262.9 > 109 10 125 > 47 1033 Vinclozolin 28.987 187 > 124 20 197.9 > 145 1534 Heptachlor 29.349 271.7 > 236.9 15 273.7 > 238.9 1535 Transfluthrin 29.422 163.1 > 91.1 10 163.1 > 143.1 2036 Alachlor 29.549 188.1 > 160.2 10 160 > 132.1 1037 Tridiphane 30.156 187.1 > 159.1 10 173.1 > 145 1538 Ronnel (Fenchlorphos) 30.186 285 > 269.9 15 286.9 > 272 1539 Fenitrothion 31.495 125.1 > 47 15 125.1 > 79 540 Ethofumesate 31.805 206.9 > 161.1 5 161 > 105.1 1041 Dichlofluanid 32.098 123 > 77.1 20 223.9 > 123.1 1042 Musk ketone 33.244 278.9 > 191 10 278.9 > 118 2043 Parathion 33.688 138.9 > 109 5 290.9 > 109 1044 Dichlorobenzophenone, 4,4′- 33.784 139 > 111 10 139 > 75.1 3045 DCPA (Dacthal,Chlorthal-dimethyl) 33.985 298.9 > 221 25 300.9 > 223 2546 Dicapthon (Isochlorthion) 34.040 261.9 > 216.1 15 124.9 > 44.1 1047 Fenson 34.544 141 > 77.1 5 267.9 > 77.1 2048 Chlorthion 34.572 125.1 > 47.1 10 125.1 > 79 549 Nitrothal-isopropyl 34.610 236 > 194.1 10 194 > 148.1 1050 Trichloronat 34.768 296.8 > 268.9 10 298.8 > 270.9 1051 Bromophos 35.215 124.9 > 47 10 330.8 > 315.8 1552 Isodrin 35.321 193 > 123 30 193 > 157 2053 Chlozolinate 35.718 186 > 145 15 188.1 > 147 1554 Heptachlor exo-epoxide (isomer B) 36.543 352.8 > 262.9 15 354.8 > 264.9 1555 Pendimethalin (Penoxaline) 36.794 251.8 > 162.2 10 251.8 > 161.1 1556 Phenthoate 38.056 274 > 121 10 274 > 125 1557 Fipronil 38.766 350.8 > 254.8 15 366.8 > 212.8 2558 Chlordane-trans (gamma) 39.041 372.8 > 265.8 15 271.7 > 236.9 1559 Chlorflurecol-methyl 39.116 215 > 152 20 217 > 152 2560 Methidathion 39.344 144.9 > 85 5 144.9 > 58.1 1561 DDE-o,p′ 39.749 246 > 176.2 30 248 > 176.2 3062 Endosulfan II (beta isomer) 40.193 206.9 > 172 15 194.9 > 158.9 1063 Nonachlor, cis- 41.176 406.8 > 299.8 15 408.8 > 199.8 1564 TCMTB (Benthiazole) 41.292 180 > 136 15 180 > 109 3065 Flumetralin 41.316 143 > 107.1 20 143 > 117 2066 Chlorfenson 41.649 175 > 111 10 111 > 75 1567 Fluorodifen 42.449 190 > 126.1 10 190 > 75 2068 Prothiofos 42.456 113 > 94.9 10 266.9 > 239 569 Dieldrin 42.815 277 > 241 5 262.9 > 193 3570 DDE-p,p′ 43.070 246.1 > 176.2 30 315.8 > 246 1571 Aramite I 43.705 175 > 107.1 20 175 > 135.1 1072 Oxadiazon 43.710 174.9 > 112 15 174.9 > 76 3573 DDD-o,p′ 43.811 235 > 165.2 20 237 > 165.2 2074 Endrin 44.626 262.8 > 193 35 244.8 > 173 3075 Nitrofen 44.842 202 > 139.1 20 282.9 > 253 10
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Table 1 (Continued)
Peak No. Pesticides Retention time (min) Quantitation RM 1 CE (v) Identification RM 2 CE (v)
76 Ethylan (ethyl-DDD, Perthane) 45.301 223.1 > 167.1 10 223.1 > 179.1 2077 Chlorfenapyr 45.473 136.9 > 102 15 246.9 > 227 1578 Chloropropylate 45.817 139.1 > 111 15 251.1 > 139.1 1579 Chlorobenzilate 45.828 139.1 > 111 10 251.1 > 139.1 1580 DDD-p,p′ 46.457 234.9 > 165.1 20 236.9 > 165.2 2081 DDT-o,p′ 46.473 235 > 165.2 20 237 > 165.2 2082 Diofenolan I 48.291 299.9 > 186 10 186 > 77.1 2583 Cyanofenphos 48.357 169 > 141.1 5 169 > 77.1 2584 DDT-p,p′ 48.470 235 > 165.2 20 237 > 165.2 2085 Diclofop-methyl 49.766 253 > 162.1 15 339.9 > 252.9 1086 Fluotrimazole 50.337 310.9 > 165.1 15 310.9 > 233 1587 Spiromesifen 50.915 272 > 254.2 5 272 > 209.2 1088 Endrin ketone 50.946 316.8 > 100.8 10 316.8 > 280.7 589 Fenpiclonil 51.215 236 > 174.1 20 236 > 201.2 1090 Bifenox 52.404 340.9 > 309.9 10 189.1 > 126 2091 Tetradifon 52.845 158.9 > 131 10 226.9 > 199 1592 Phenothrin I 52.965 122.9 > 81.1 5 183 > 155.1 593 Mirex 53.582 271.8 > 236.8 15 273.8 > 238.8 1594 Cyhalothrin (lambda) 54.263 208 > 181 5 197 > 141 1095 Cyfluthrin I 58.406 162.9 > 90.9 15 162.9 > 127 596 Cypermethrin 58.411 181 > 152 20 163 > 127 1097 Halfenprox 58.518 262.9 > 169 20 265 > 117.1 1098 Boscalid 58.631 140 > 112 10 140 > 76 2599 Flucythrinate I 59.721 156.9 > 107.1 15 198.9 > 157 10
100 Fenvalerate I 61.562 167 > 125.1 5 208.9 > 141.1 15101 Esfenvalerate (Fenvalerate A-alpha) 62.360 167 > 125.1 10 181 > 152.1 25
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Fig. 1. Schematic representation of the modified sample preparation. MNPs: Fe3O4
Commercial vegetables and fruits (cucumbers, tomatoes,ranges and apples) were cut into small pieces and comminutedy the grinder to obtain good sample homogeneity. Ten gramsf the sample was weighted into a centrifuge tube (50 mL), andppropriate volumes of pesticide standards were also added. Theamples were extracted with 10 mL acetonitrile (MeCN) by theomogeniser for 30 s. One gram of sodium chloride and 4 g anhy-rous magnesium sulphate were added and vortexed immediatelynd vigorously for 1.5 min. After centrifugation for 5 min at 5000evolutions per minute (rpm), the supernatant (1 mL) was trans-erred to an Eppendorf vial (1.5 mL) containing 100 mg anhydrous
gSO4, 10 mg GCB, 50 mg PSA and 40 mg MNPs (optimised con-ition). The vial was shaken in a vortex mixer for 60 s (optimisedondition), and then the supernatant was collected with the aidf an external magnet. One microlitre of the above solution wasnjected into the GC–MS/MS.
.4. Instrumentation and analytical conditions
Characterisation of the MNP morphology was performed with aEOL JEM-2010 high-resolution transmission electron microscopeTEM) at an accelerating voltage of 200 kV.
Please cite this article in press as: Y.-F. Li, et al., Determination of mueasy, cheap, effective, rugged and safe method with magnetic nanopChromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.01
Analysis of all pesticides was performed by a gas chro-atograph Agilent 7890A connected to an Agilent 7000B triple
uadrupole tandem mass detector equipped with a splitless injec-or and a HP-5 ms capillary column (methyl phenyl siloxane,
etic nanoparticles; GCB: graphitised carbon black; PSA: primary secondary amine.
30 m × 0.25 mm × 0.25 �m). Helium and nitrogen were used ascollision cell gases at a constant flow of 2.25 mL min−1 and1.5 mL min−1, respectively. Aliquots of 1 �L of the sample extractwere injected into the gas chromatograph. The oven tempera-ture programme was as follows: starting temperature 95 ◦C held1.5 min, increased at 7 ◦C/min to 165 ◦C, then increased to 210 ◦Cat 5 ◦C/min and finally increased to 280 ◦C and held for 8 min. Themass spectrometry was performed in electron ionisation (EI) modewith an ionising energy of 70 eV. The detector interface was setat 250 ◦C, and the ion source temperature was set at 230 ◦C. Theanalysis was performed in multi reaction monitoring (MRM) modebased on MS/MS transitions. Optimisation of the parameters forMS/MS transitions was conducted for each target compound. Theoptimised MS/MS conditions are presented in Table 1. The qualifi-cation and quantification of the pesticides were performed underthe guidelines of European Union legislation (2002/657/EC) [37].Agilent Mass Hunter Data Acquisition, Qualitative Analysis andQuantitative Analysis software were used for the method devel-opment and data acquisition.
3. Results and discussion
ltiple pesticides in fruits and vegetables using a modified quick,articles and gas chromatography tandem mass spectrometry, J.1
3.1. Characterisation of MNPs
The micro-morphology of the MNPs was observed by TEM(Fig. 2). Obviously, the MNPs had a regular shape, close to spherical
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Fig. 3. Effect of (A) mass of GCB, (B) mass of Fe3O4 and (C) clean-up time on theextraction efficiency of the studied pesticides (200 �g kg−1 each).
Fig. 4. Photography of clean-up performance by different DSPE adsorbents: (a) 2 mLcucumber extracts with DSPE clean-up by 200 mg anhydrous MgSO4, 5 mg GCB and50 mg PSA; (b) 2 mL cucumber extracts with DSPE clean-up by 200 mg anhydrous
Fig. 2. TEM images of MNPs.
orphology. Their mean size was approximately 10–20 nm, andhe particle size was uniform.
.2. Optimisation of the amount of adsorbents
Sample clean-up was necessary to remove co-extracted inter-erences. In the experiments, two types of absorbents, graphitearbon black (GCB) and Fe3O4, were tested for the eight investigatedesticides (pentachloronitrobenzene, fonofos, vinclozolin, alpha-ndosulfan, dieldrin, 2,4′-DDD, beta-endosulfan and cyhalothrin)rom cucumber samples. The recoveries of 8 pesticides in fiveifferent amounts of GCB (0–20 mg) are shown in Fig. 3A. The recov-ries of 5 mg and 10 mg GCB were above 80% and meet the testequirements. Taking purification efficiency into account, 10 mgCB was selected for clean-up procedure. When more than 10 mgCB was added, the recoveries of structurally planar targets began
o decrease. Furthermore, the recovery of the more planar targettructures decreased the most. The recoveries of target pesticidesn Fe3O4 (0–50 mg) are shown in Fig. 3B. When the amount of Fe3O4dded was below 20 mg, the magnetic performance was not obvi-us, and absorbent mixture could not be isolated quickly with theelp of a magnetic field. The Fe3O4 concentration in the adsor-ent mixture may be too low in this case. When the amount ofe3O4 added was close to 40 mg, the recoveries were better. In addi-ion, the reduction in the recovery of planar pesticides caused byhe increased Fe3O4 was far less than that incurred by increasedmounts of GCB.
The clean-up time for the target pesticides also needs to bexamined. The clean-up time varied from 30 to 90 s when the otherarameters were held constant. The results (Fig. 3C) indicated thathe extraction efficiency increased with increased clean-up timerom 30 to 60 s, and then began to decrease from 60 to 90 s. Finally,e adjusted the clean-up time to 60 s.
.3. Effect of extraction with and without MNPs
Proper use of sorbent(s) is critical to removing matrix inter-
Please cite this article in press as: Y.-F. Li, et al., Determination of multiple pesticides in fruits and vegetables using a modified quick,easy, cheap, effective, rugged and safe method with magnetic nanoparticles and gas chromatography tandem mass spectrometry, J.Chromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.011
erences. Primary and secondary amine sorbent (PSA) is the baseorbent used for QuEChERS cleaning of fruit and vegetable extractsecause it removes organic acids and sugars that might adverselyffect chromatographic performance. Comparing Fig. 4a and b,
MgSO4, 10 mg GCB and 50 mg PSA; (c) 2 mL cucumber extracts with DSPE clean-up by 200 mg anhydrous MgSO4, 10 mg GCB, 50 mg PSA and 40 mg MNPs; (d) 1 mLcucumber extracts with DSPE clean-up by 100 mg anhydrous MgSO4, 10 mg GCB,50 mg PSA and 40 mg MNPs.
Please cite this article in press as: Y.-F. Li, et al., Determination of multiple pesticides in fruits and vegetables using a modified quick,easy, cheap, effective, rugged and safe method with magnetic nanoparticles and gas chromatography tandem mass spectrometry, J.Chromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.011
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Fig. 5. Chromatograms of cucumber extract cleaned in the presence (a) of MNPs (b) or absence.Table 2Determination coefficient (r2), LODs (�g kg−1) and LOQs (�g kg−1) for the matrix matched curves of the 101 pesticides.
Pesticides Coefficient (r2) LOD(�g kg−1)
LOQ(�g kg−1)
Pesticides Coefficient (r2) LOD(�g kg−1)
LOQ(�g kg−1)
DBCP (Dibromo-3-chloropropane,1,2-)
0.9993 0.03 0.11 Isodrin 0.9996 0.71 2.36
Naphthalene-d8 0.9998 0.03 0.10 Chlozolinate 0.9997 0.23 0.77Dichlorvos 0.9995 0.12 0.41 Heptachlor exo-epoxide (isomer B) 0.9992 2.03 6.77EPTC 0.9998 0.60 2.00 Pendimethalin (Penoxaline) 0.9990 2.17 7.25Dichlormid 0.9993 0.22 0.74 Phenthoate 0.9976 0.98 3.27Dichloroaniline, 3,5- 0.9994 0.09 0.31 Fipronil 0.9993 1.40 4.67Vernolate 0.9996 1.32 4.41 Chlordane-trans (gamma) 0.9996 0.80 2.67Nitrapyrin 0.9925 0.76 2.53 Chlorflurecol-methyl 0.9977 0.13 0.43Propham 0.9998 0.45 0.51 Methidathion 0.9993 1.50 5.01Etridiazole (Terrazole,Echlomezol) 0.9935 0.58 1.93 DDE-o,p′ 0.9997 0.32 1.07Phthalimide 0.9910 0.10 0.34 Endosulfan II (beta isomer) 0.9994 0.75 2.51Acenaphthene 0.9990 0.54 1.81 Nonachlor, cis- 0.9995 1.08 3.61Methacrifos 0.9996 0.19 0.65 TCMTB (Benthiazole) 0.9995 1.34 4.47Chloroneb 0.9998 0.17 0.57 Flumetralin 0.9933 0.98 3.26XMC (3,5-Dimethylpheny N-MethylCarbamate)
0.9969 0.26 0.87 Chlorfenson 0.9980 0.10 0.34
Chlorfenprop-methyl 0.9991 0.06 0.19 Fluorodifen 0.9994 0.73 2.43Tecnazene (TCNB) 0.9990 0.45 1.51 Prothiofos 0.9981 0.60 2.01Chlorethoxyfos 0.9987 0.16 0.54 Dieldrin 0.9990 1.86 6.20Ethalfluralin 0.9990 1.17 3.90 DDE-p,p′ 0.9996 0.74 2.47Chlordimeform 0.9979 1.16 3.86 Aramite I 0.9995 0.08 0.26Thiometon 0.9990 1.02 3.42 Oxadiazon 0.9998 0.06 0.21Schradan 0.9938 0.94 3.14 DDD-o,p′ 0.9992 0.07 0.24Dimethipin 0.9989 1.20 4.00 Endrin 0.9990 0.96 3.19Sebuthylazine-desethyl 0.9990 0.65 2.18 Nitrofen 0.9973 0.62 2.06BHC-gamma (Lindane, gamma HCH) 0.9988 0.12 0.41 Ethylan (ethyl-DDD, Perthane) 0.9995 1.35 4.51Disulfoton 0.9994 0.22 0.74 Chlorfenapyr 0.9995 1.20 4.02Fluchloralin 0.9972 0.57 1.91 Chloropropylate 0.9993 0.25 0.83Tefluthrin, cis- 0.9995 0.15 0.50 Chlorobenzilate 0.9993 0.17 0.56Bromocyclen 0.9999 1.50 5.11 DDD-p,p′ 0.9989 0.04 0.13Monalide 0.9992 0.56 1.87 DDT-o,p′ 0.9993 0.06 0.21Fenchlorphos oxon 0.9911 1.22 4.06 Diofenolan I 0.9991 0.27 0.91Parathion-methyl 0.9959 0.80 2.66 Cyanofenphos 0.9991 0.15 0.50Vinclozolin 0.9996 0.87 2.91 DDT-p,p′ 0.9908 0.04 0.13Heptachlor 0.9985 0.93 3.11 Diclofop-methyl 0.9993 0.18 0.61Transfluthrin 0.9993 1.44 4.82 Fluotrimazole 0.9995 0.18 0.60Alachlor 0.9995 0.44 1.47 Spiromesifen 0.9997 0.64 2.13Tridiphane 0.9962 0.24 0.81 Endrin ketone 0.9994 0.87 2.91Ronnel (Fenchlorphos) 0.9986 0.23 0.78 Fenpiclonil 0.9993 0.36 1.99Fenitrothion 0.9962 0.85 2.84 Bifenox 0.9997 0.75 2.49Ethofumesate 0.9996 0.38 1.27 Tetradifon 0.9992 0.58 1.93Dichlofluanid 0.9994 1.05 3.51 Phenothrin I 0.9992 1.15 3.85Musk ketone 0.9996 1.32 4.42 Mirex 0.9990 0.05 0.17Parathion 0.9991 0.37 1.23 Cyhalothrin (lambda) 0.9991 0.21 0.72Dichlorobenzophenone, 4,4′- 0.9994 0.15 0.51 Cyfluthrin I 0.9992 0.42 1.39DCPA (Dacthal,Chlorthal-dimethyl) 0.9994 0.43 1.43 Cypermethrin 0.9991 0.58 1.94Dicapthon (Isochlorthion) 0.9994 0.45 1.51 Halfenprox 0.9991 0.47 1.57Fenson 0.9992 0.10 0.34 Boscalid 0.9993 0.17 0.58Chlorthion 0.9950 0.38 1.27 Flucythrinate I 0.9993 0.36 1.20Nitrothal-isopropyl 0.9993 0.40 1.34 Fenvalerate I 0.9992 0.42 1.39Trichloronat 0.9970 0.41 1.38 Esfenvalerate(Fenvalerate A-alpha) 0.9991 0.50 1.61Bromophos 0.9991 0.55 1.85
Please cite this article in press as: Y.-F. Li, et al., Determination of multiple pesticides in fruits and vegetables using a modified quick,easy, cheap, effective, rugged and safe method with magnetic nanoparticles and gas chromatography tandem mass spectrometry, J.Chromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.011
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Y.-F. Li et al. / J. Chromatogr. A xxx (2014) xxx–xxx 7
Table 3Recoveries (%) (n = 5) and repeatability (RSD %) obtained from 101 pesticides spiked in cucumber, tomato, orange and apple at three levels.
Pesticides Cucumber Tomato
10 �g kg−1 50 �g kg−1 200 �g kg−1 10 �g kg−1 50 �g kg−1 200 �g kg−1
Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%)
DBCP (Dibromo-3-chloropropane, 1,2-) 98.7 2.8 101.1 1.2 101.7 3.0 101.6 1.4 105.3 2.3 106.8 1.2Naphthalene-d8 96.7 3.6 96.4 2.0 95.3 1.8 94.55 0.9 96.9 3.0 95.7 1.3Dichlorvos 95.0 2.7 90.7 1.2 101.3 1.1 104.07 1.6 107.6 1.1 110.6 1.5EPTC 100.5 2.2 96.7 2.2 100.6 2.8 100.90 2.4 103.4 2.7 104.7 1.5Dichlormid 98.4 1.4 103.5 1.6 100.2 3.9 99.40 2.2 104.8 2.4 106.8 2.7Dichloroaniline, 3,5- 85.0 1.8 88.2 1.9 82.7 3.8 83.19 1.7 87.7 2.1 88.9 3.7Vernolate 98.7 2.4 98.0 3.3 102.9 3.6 99.60 1.0 103.2 1.4 102.1 1.9Nitrapyrin 88.7 3.6 93.8 6.5 108.1 6.6 100.69 3.7 103.2 2.7 104.7 2.5Propham 96.8 2.6 100.9 2.9 103.1 3.1 98.12 2.5 101.9 2.8 102.6 1.8Etridiazole (Terrazole,Echlomezol) 99.4 3.3 110.3 5.2 96.7 5.8 101.3 3.0 109.7 4.9 108.5 4.3Phthalimide 104.7 2.7 95.7 1.4 86.2 9.5 83.5 3.2 91.2 5.8 87.7 2.1Acenaphthene 86.6 1.6 86.9 2.7 87.4 5.1 82.2 3.3 89.8 3.1 93.4 1.4Methacrifos 96.7 0.7 97.5 2.3 102.7 3.0 99.2 1.1 102.3 2.4 104.8 1.4Chloroneb 91.3 5.5 94.8 4.6 95.4 7.8 86.7 3.7 97.6 4.6 97.4 4.2XMC (3,5-Dimethylpheny N-Methyl Carbamate) 99.8 2.4 95.9 1.5 102.4 5.0 97.4 2.2 97.8 2.1 102.3 1.8Chlorfenprop-methyl 89.4 1.6 95.5 1.6 97.3 3.5 96.3 2.7 98.4 3.8 99.3 3.8Tecnazene (TCNB) 89.4 3.2 93.9 2.5 92.9 6.0 84.8 1.8 88.7 1.2 89.6 1.8Chlorethoxyfos 97.0 1.4 98.0 2.7 101.7 3.6 99.1 3.2 103.8 3.1 104.7 2.4Ethalfluralin 96.3 2.1 96.5 1.1 102.1 4.0 100.9 2.9 101.2 4.7 104.6 4.0Chlordimeform 94.0 1.5 93.9 3.0 99.1 4.3 92.2 4.4 93.4 2.2 92.1 3.6Thiometon 95.4 1.3 95.0 2.1 100.9 3.5 91.3 3.9 96.4 4.8 98.2 4.3Schradan 95.2 3.3 88.3 1.5 84.5 6.5 94.0 3.2 90.1 3.3 97.3 2.6Dimethipin 97.8 4.7 102.5 1.3 98.9 3.8 100.7 5.7 105.8 4.4 108.4 3.2Sebuthylazine-desethyl 95.4 2.8 100.3 1.1 97.8 4.8 94.8 3.5 95.3 6.7 94.6 2.9BHC-gamma (Lindane, gamma HCH) 95.3 1.4 99.8 1.5 96.9 3.8 96.5 3.7 101.6 2.8 100.9 2.8Disulfoton 95.3 0.6 95.1 1.7 101.7 4.0 90.8 2.7 99.5 1.6 102.6 1.9Fluchloralin 96.1 1.6 97.3 2.3 102.8 6.6 100.4 3.4 104.9 4.2 109.3 2.3Tefluthrin, cis- 96.2 1.3 97.5 1.7 101.6 4.9 97.4 2.4 101.2 1.9 106.0 1.5Bromocyclen 94.2 3.9 97.6 1.1 100.7 4.0 95.0 4.6 99.7 4.2 101.2 3.9Monalide 96.3 2.0 97.6 0.5 101.6 5.8 98.6 2.2 101.8 2.5 105.4 3.0Fenchlorphos oxon 88.8 5.4 86.7 2.8 100.1 5.8 90.0 3.8 94.5 3.9 94.9 4.6Parathion-methyl 97.4 3.3 96.3 2.8 100.2 5.3 97.9 3.9 101.5 2.0 100.4 2.5Vinclozolin 105.6 0.8 97.6 3.7 103.3 3.9 100.1 1.9 99.8 2.6 104.5 2.8Heptachlor 91.0 2.0 94.8 0.4 101.2 3.8 97.2 2.9 103.6 2.2 104.8 1.5Transfluthrin 96.2 2.3 96.0 1.6 100.5 3.5 95.4 3.5 96.5 4.6 100.3 2.4Alachlor 98.0 2.3 97.6 1.4 101.9 3.9 97.7 3.7 100.4 3.2 107.8 2.1Tridiphane 93.6 2.5 96.0 0.9 100.9 4.9 98.6 3.0 101.2 2.1 106.5 1.4Ronnel (Fenchlorphos) 82.7 1.4 90.6 1.7 88.1 7.2 81.9 2.4 93.8 2.3 96.7 1.0Fenitrothion 95.6 2.6 88.5 1.5 94.5 5.6 95.9 3.9 94.3 2.6 96.2 1.5Ethofumesate 96.9 1.9 101.8 1.2 99.2 3.1 97.8 3.7 102.6 1.4 103.9 1.7Dichlofluanid 90.8 10.5 102.0 4.1 103.7 7.4 99.9 5.7 104.3 2.0 107.1 1.3Musk ketone 99.0 4.6 105.6 4.5 96.7 3.6 101.6 6.8 105.8 3.7 103.2 2.1Parathion 99.3 2.6 102.2 3.9 95.9 5.0 97.81 2.4 106.4 3.6 105.3 2.9Dichlorobenzophenone, 4,4′- 77.3 2.8 83.3 2.6 82.8 6.3 76.97 3.6 82.1 2.9 88.7 2.8DCPA (Dacthal,Chlorthal-dimethyl) 98.7 0.8 102.4 4.4 94.9 3.5 95.4 1.2 104.2 4.8 103.1 1.4Dicapthon (Isochlorthion) 91.6 2.7 99.7 6.4 92.3 6.4 91.4 0.8 96.7 4.6 98.6 2.6Fenson 99.7 1.5 103.8 3.7 94.6 4.0 95.8 4.6 102.5 3.3 103.7 3.7Chlorthion 87.2 6.7 102.5 6.4 91.9 5.5 96.2 8.5 104.6 7.5 106.3 5.3Nitrothal-isopropyl 83.9 1.8 90.0 2.1 90.7 6.0 88.5 4.4 95.1 4.0 101.2 2.4Trichloronat 81.9 3.1 80.4 0.9 83.2 6.8 83.8 7.6 86.4 6.6 87.9 4.5Bromophos 81.1 3.6 82.9 2.7 83.5 7.2 85.1 6.5 90.8 4.4 90.4 3.2Isodrin 99.5 0.8 99.5 5.0 95.2 2.8 93.4 2.4 102.5 2.1 105.1 1.1Chlozolinate 105.1 1.9 109.4 2.8 101.5 3.0 106.8 1.1 110.3 1.6 111.7 1.3Heptachlor exo-epoxide (isomer B) 97.3 1.8 98.3 4.5 94.8 2.9 98.8 2.2 99.2 2.4 103.8 1.4Pendimethalin (Penoxaline) 82.1 5.4 88.8 2.9 89.3 2.5 83.3 6.7 90.2 4.4 91.6 3.6Phenthoate 101.8 2.2 102.5 7.3 97.3 4.2 97.9 3.9 102.4 5.8 101.8 4.7Fipronil 96.5 2.6 103.0 3.4 92.5 2.8 96.3 4.8 99.6 4.0 99.2 3.2Chlordane-trans (gamma) 94.8 6.2 99.8 3.8 94.1 3.3 94.8 5.4 96.5 5.8 98.9 6.7Chlorflurecol-methyl 86.7 3.8 87.6 3.4 84.2 6.0 80.2 4.6 87.5 5.2 88.0 4.1Methidathion 95.4 5.7 102.8 3.2 95.1 4.7 94.6 6.7 98.2 4.4 104.7 3.7DDE-o,p′ 95.9 4.2 101.5 4.7 95.0 3.1 93.4 4.8 97.6 4.7 98.2 4.0Endosulfan II (beta isomer) 106.1 2.8 100.2 7.7 97.6 6.4 91.3 3.7 98.1 3.7 103.8 2.2Nonachlor, cis- 100.8 3.2 99.5 6.2 96.2 3.0 97.4 2.9 101.4 3.9 103.6 3.2TCMTB (Benthiazole) 89.3 4.7 98.3 5.6 88.4 8.5 87.6 5.8 94.8 4.8 95.3 3.3Flumetralin 91.4 1.4 101.9 5.1 93.4 3.9 95.3 3.7 101.4 4.6 104.5 3.7Chlorfenson 91.0 2.6 100.7 5.0 94.7 4.7 92.7 3.7 97.8 3.5 98.2 3.4Fluorodifen 100.3 6.7 103.1 4.5 99.2 4.8 93.3 5.7 101.6 6.7 103.5 4.3Prothiofos 74.2 2.7 87.0 3.4 85.8 7.0 76.1 3.7 88.9 4.8 90.6 2.9Dieldrin 98.4 6.2 95.7 3.5 92.7 4.1 95.1 5.9 98.7 5.1 95.4 3.8DDE-p,p′ 91.5 1.5 100.0 3.7 92.5 2.7 92.1 2.7 101.7 2.7 103.4 2.1Aramite I 108.9 9.1 98.1 5.3 95.8 2.9 95.7 7.2 99.2 4.4 101.3 3.3Oxadiazon 95.9 1.5 96.5 2.3 102.6 3.0 97.1 3.5 101.6 2.1 103.4 2.0
Please cite this article in press as: Y.-F. Li, et al., Determination of multiple pesticides in fruits and vegetables using a modified quick,easy, cheap, effective, rugged and safe method with magnetic nanoparticles and gas chromatography tandem mass spectrometry, J.Chromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.011
ARTICLE IN PRESSG ModelCHROMA-355701; No. of Pages 11
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Table 3 (Continued).
Pesticides Cucumber Tomato
10 �g kg−1 50 �g kg−1 200 �g kg−1 10 �g kg−1 50 �g kg−1 200 �g kg−1
Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%)
DDD-o,p′ 91.7 1.6 96.9 4.2 100.0 2.9 93.4 2.9 99.5 1.9 101.7 1.5Endrin 98.0 4.1 94.0 4.9 104.5 4.0 94.9 3.6 101.2 3.0 100.4 2.5Nitrofen 97.0 5.5 98.7 4.6 102.8 5.6 93.6 6.6 98.0 4.6 102.6 3.8Ethylan (ethyl-DDD, Perthane) 95.3 2.7 106.9 6.2 98.1 3.2 94.8 3.0 103.4 3.6 100.1 2.5Chlorfenapyr 97.1 4.0 97.4 3.1 94.8 3.6 95.4 5.6 102.8 4.4 104.6 4.0Chloropropylate 97.1 1.9 102.9 5.0 95.2 2.7 95.8 3.2 98.5 3.2 99.3 2.8Chlorobenzilate 97.1 1.9 102.8 4.5 95.2 3.3 95.8 2.5 98.6 2.9 99.3 1.7DDD-p,p′ 95.4 2.6 94.2 4.6 103.2 3.5 95.2 3.9 99.5 3.1 102.4 2.7DDT-o,p′ 95.9 3.5 94.3 5.7 103.2 3.5 95.4 4.6 98.2 3.7 103.6 2.3Diofenolan I 94.4 3.1 94.1 3.2 102.7 4.0 92.8 7.3 103.2 5.9 101.7 4.9Cyanofenphos 86.0 3.3 96.4 2.6 92.0 6.2 87.9 3.4 95.7 2.7 97.8 2.2DDT-p,p′ 87.0 4.8 108.5 8.6 95.1 4.8 96.9 5.3 100.3 4.9 101.2 3.2Diclofop-methyl 89.2 2.9 100.9 3.8 94.0 4.7 93.2 3.1 98.7 4.3 102.5 3.7Fluotrimazole 93.0 2.0 92.3 4.1 101.7 3.0 94.3 3.7 97.6 3.3 103.0 1.6Spiromesifen 92.4 3.8 95.4 4.5 103.1 3.0 95.1 4.7 101.3 2.7 98.7 2.1Endrin ketone 92.4 4.5 104.5 5.4 92.9 4.2 94.4 4.2 97.4 3.3 97.5 1.6Fenpiclonil 95.5 3.1 101.56 6.9 92.1 5.6 90.6 3.9 95.4 3.6 99.8 2.9Bifenox 85.3 3.5 98.06 4.8 92.4 5.5 91.3 2.4 97.3 3.1 98.9 3.6Tetradifon 95.5 2.3 100.2 5.1 105.0 4.3 91.7 4.5 98.1 3.3 102.2 1.3Phenothrin I 96.9 3.2 99.9 4.3 98.8 4.4 89.5 3.8 98.7 2.2 95.4 1.7Mirex 91.2 4.3 100.6 4.7 95.6 3.0 91.4 3.6 101.3 2.5 102.5 2.2Cyhalothrin (lambda) 93.4 5.9 95.6 4.2 101.7 4.1 95.20 5.7 102.8 4.4 104.6 2.5Cyfluthrin I 97.8 5.1 96.5 3.3 100.5 6.5 98.4 4.9 105.7 3.7 107.9 3.5Cypermethrin 102.1 5.4 98.3 8.2 101.9 6.5 92.3 4.6 97.0 2.2 100.2 3.6Halfenprox 78.6 9.3 89.1 5.3 88.2 7.6 82.6 5.4 89.5 3.2 93.4 5.8Boscalid 84.4 7.8 88.2 7.3 86.3 8.6 80.5 5.3 88.2 2.2 93.9 2.9Flucythrinate I 99.6 4.3 99.5 5.8 98.9 5.5 91.7 6.9 95.1 5.4 97.0 3.3Fenvalerate I 98.5 6.5 98.3 5.2 98.8 6.2 92.5 7.4 98.3 5.4 99.6 4.6Esfenvalerate (Fenvalerate A-alpha) 101.4 6.4 101.3 7.7 99.0 6.2 98.4 4.2 101.2 2.1 105.7 2.4
Pesticides Orange Apple
10 �g kg −1 50 �g kg −1 200 �g kg −1 10 �g kg −1 50 �g kg −1 200 �g kg −1
Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%)
DBCP (Dibromo-3-chloropropane, 1,2-) 92.3 3.2 98.1 1.8 98.7 3.5 96. 9 2.2 101.3 2.8 102.8 1.7Naphthalene-d8 90.6 4.1 94.3 3.2 93.3 2.6 92.6 1.8 93.4 4.0 94.8 1.9Dichlorvos 89.1 2.3 90.8 1.8 89.9 1.3 85.6 2.3 90.2 3.4 90.6 2.4EPTC 91.0 1.3 91.3 2.2 89.7 2.7 94.3 3.4 94.0 2.8 96.6 1.5Dichlormid 89.7 2.3 91.6 1.8 87.2 2.7 99.5 2.1 100.4 2.6 100.1 2.0Dichloroaniline, 3,5- 80.5 1.2 81.9 1.9 85.4 3.9 85.8 1.4 88.4 1.9 82.7 3.3Vernolate 88.3 3.3 91.3 3.0 87.2 3.7 96.3 0.8 99.9 1.2 97.9 1.5Nitrapyrin 81.4 2.4 85.4 3.2 86.4 3.4 98.1 2.8 91.0 3.0 93.8 2.7Propham 90.8 3.3 91.2 2.4 87.8 2.3 89.3 1.3 96.7 2.5 96.8 3.4Etridiazole (Terrazole,Echlomezol) 88.6 4.4 87.4 4.0 86.5 2.6 86.6 3.1 94.6 3.5 96.7 4.9Phthalimide 80.1 4.0 83.4 2.6 81.5 4.5 89.3 2.7 84.8 4.6 86.2 2.6Acenaphthene 79.8 2.6 80.4 2.6 82.0 1.4 98.6 3.4 82.7 4.3 87.4 1.7Methacrifos 89.6 1.6 90.4 1.3 89.4 2.8 89.0 2.5 95.0 2.9 97.5 1.5Chloroneb 83.1 4.3 86.7 4.0 84.0 3.3 89.9 3.0 89.7 3.8 95.4 4.7XMC (3,5-Dimethylpheny N-Methyl Carbamate) 87.2 3.2 90.0 3.1 88.4 1.8 103.4 1.4 94.4 1.4 95.8 1.8Chlorfenprop-methyl 94.5 2.4 87.4 2.5 87.0 2.8 88.0 2.8 94.7 2.7 97.2 3.2Tecnazene (TCNB) 80.9 2.3 81.2 2.5 85.2 1.9 102.5 2.5 88.0 1.7 92.8 1.9Chlorethoxyfos 87.4 2.3 86.5 2.4 89.1 2.6 89.3 3.9 94.0 3.3 97.9 1.6Ethalfluralin 84.2 2.1 89.3 1.8 85.3 2.3 95.1 2.4 97.8 2.5 96.5 3.5Chlordimeform 87.6 1.3 87.0 1.8 84.7 1.8 93.5 4.7 90.7 3.7 93.8 3.7Thiometon 86.3 3.0 89.3 2.1 88.1 1.3 88.9 4.3 95.1 4.7 95.0 4.3Schradan 74.1 3.8 75.8 2.4 79.7 1.5 74.6 3.9 77.7 3.0 79.4 3.9Dimethipin 91.1 3.8 91.8 2.5 90.0 1.4 116.6 5.5 99.2 4.6 98.9 3.5Sebuthylazine-desethyl 82.5 2.3 83.9 2.4 86.4 3.0 103.5 4.9 93.8 4.4 95.7 2.2BHC-gamma (Lindane, gamma HCH) 84.9 1.3 86.3 2.2 89.7 2.7 87.0 3.3 94.4 3.8 96.9 4.6Disulfoton 87.6 1.4 87.1 1.4 88.2 3.1 100.8 3.4 92.3 1.3 95.1 1.3Fluchloralin 84.7 2.6 85.6 2.3 88.9 2.8 105.0 2.5 93.5 4.7 97.3 2.3Tefluthrin, cis- 86.1 1.8 85.3 1.7 86.9 3.6 101.7 2.2 94.5 3.8 97.4 2.9Bromocyclen 85.6 3.4 87.6 2.8 89.3 1.4 91.4 2.6 92.8 2.3 96.7 3.4Monalide 85.4 1.3 87.9 1.1 89.9 3.2 100.6 3.9 92.9 2.4 97.5 3.5Fenchlorphos oxon 76.2 4.8 79.9 3.5 81.7 3.1 78.9 4.3 83.2 4.0 86.7 4.2Parathion-methyl 82.1 3.3 83.5 3.0 86.1 2.9 94.3 3.4 99.2 2.0 96.3 2.9Vinclozolin 89.3 1.5 91.6 1.7 88.8 2.7 86.3 1.9 92.6 1.6 97.6 2.5Heptachlor 87.3 2.1 87.6 1.4 89.2 2.3 103.2 2.7 94.0 2.7 94.8 2.9Transfluthrin 86.3 3.5 87.9 2.6 89.5 3.7 81.8 3.5 92.6 3.6 95.9 2.8Alachlor 86.0 3.7 91.3 2.4 92.0 1.6 93.8 2.0 90.7 2.8 97.6 3.6Tridiphane 84.6 2.5 86.7 2.9 88.5 4.8 99.1 3.5 94.6 3.7 96.0 1.8
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Table 3 (Continued).
Pesticides Orange Apple
10 �g kg −1 50 �g kg −1 200 �g kg −1 10 �g kg −1 50 �g kg −1 200 �g kg −1
Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%) Rec. (%) RSD (%)
Ronnel (Fenchlorphos) 76.4 1.3 79.3 1.7 83.7 3.8 74.6 2.2 84.3 2.5 88.1 1.2Fenitrothion 81.0 3.7 84.2 2.5 85.9 1.5 85.0 2.8 91.9 2.3 94.5 3.8Ethofumesate 86.3 2.9 87.9 2.2 91.6 2.3 101.7 3.5 94.9 3.3 99.2 1.9Dichlofluanid 96.7 8.6 96.4 5.1 99.0 4.9 101.1 6.6 107.7 4.9 106.2 5.3Musk ketone 87.3 5.2 89.8 4.5 90.5 3.5 97.5 6.0 93.4 5.4 96.7 2.7Parathion 84.9 2.6 84.7 3.9 84.8 2.8 105.0 3.9 90.4 2.6 95.9 2.2Dichlorobenzophenone, 4,4′- 77.1 1.7 77.0 1.6 81.3 1.7 84.7 2.4 81.8 2.3 82.8 2.9DCPA (Dacthal,Chlorthal-dimethyl) 86.8 1.3 87.5 2.4 90.4 2.5 94.3 1.7 94.4 2.4 94.9 1.3Dicapthon (Isochlorthion) 78.8 2.8 80.7 3.4 83.8 2.5 81.6 0.4 88.1 2.6 92.3 2.6Fenson 86.3 3.3 87.7 3.7 89.5 3.4 84.9 4.0 92.6 4.4 94.6 3.4Chlorthion 80.6 5.6 82.9 6.4 80.2 5.5 89.6 7.3 84.8 5.3 91.9 2.7Nitrothal-isopropyl 80.5 2.3 83.6 2.1 84.5 1.9 96.9 5.2 84.9 4.9 90.7 2.4Trichloronat 75.4 3.3 79.3 2.9 83.5 2.3 74.5 7.2 77.7 5.2 83.2 4.9Bromophos 77.6 2.6 77.2 1.7 82.0 2.7 71.5 8.1 79.3 5.8 83.5 4.8Isodrin 86.7 2.3 86.9 1.0 88.3 2.4 91.6 3.5 89.4 3.5 95.2 1.6Chlozolinate 97.5 3.6 98.7 2.8 98.1 2.6 89.3 2.4 100.3 1.3 101.5 2.7Heptachlor exo-epoxide (isomer B) 95.6 3.3 90.4 2.5 98.9 2.1 98.4 1.5 92.2 1.4 94.8 1.2Pendimethalin (Penoxaline) 80.1 3.2 79.0 2.9 83.9 2.0 91.2 4.4 89.9 4.8 89.3 3.9Phenthoate 85.2 4.4 89.3 4.3 88.9 3.9 108.0 4.3 93.7 5.7 97.3 3.6Fipronil 92.9 3.3 93.3 3.4 85.7 2.8 108.6 4.8 101.4 3.4 97.6 3.5Chlordane-trans (gamma) 88.4 5.7 89.5 4.8 86.6 3.7 96.5 6.1 92.7 5.8 92.5 4.2Chlorflurecol-methyl 87.6 2.3 82.7 3.2 86.5 2.3 91.6 4.8 86.8 4.7 84.1 2.1Methidathion 83.5 4.3 88.4 3.2 89.4 3.4 86.6 5.3 92.9 4.4 95.1 4.7DDE-o,p′ 87.6 6.4 89.2 4.7 89.7 3.4 99.9 4.5 92.8 5.0 95.0 3.5Endosulfan II (beta isomer) 97.9 3.5 84. 6.7 85.6 5.3 95.2 2.0 90.0 2.6 94.6 1.1Nonachlor, cis- 91.3 5.1 88.5 4.2 85.6 3.4 103.4 2.9 96.5 2.6 91.2 1.3TCMTB (Benthiazole) 80.1 6.3 83.4 5.6 87.0 3.3 81.2 3.4 89.4 3.3 86.4 2.8Flumetralin 84.3 3.6 85.4 5.1 87.0 4.4 88.2 3.2 92.7 3.8 93.9 2.3Chlorfenson 88.9 3.6 86.7 4.0 87.1 2.7 95.6 3.6 92.5 3.6 94.7 1.2Fluorodifen 83.2 5.4 86.1 4.5 84.5 4.3 91.4 6.8 92.8 5.5 93.2 5.2Prothiofos 76.4 2.8 79.6 3.4 83.3 2.5 84.7 4.4 84.8 4.9 85.8 6.8Dieldrin 85.9 7.2 91.1 5.5 86.5 4.3 89.3 5.0 97.2 3.9 92.7 3.7DDE-p,p′ 83.4 3.2 86.9 3.7 84.3 2.7 93.9 3.6 90.5 2.4 92.5 4.4Aramite I 90.4 6.8 89.8 5.3 89.1 3.5 104.4 6.7 95.5 5.6 95.8 6.4Oxadiazon 85.9 3.4 90.4 2.3 87.1 3.0 101.1 2.4 96.3 2.3 96.5 1.4DDD-o,p′ 84.8 2.7 90.0 2.2 85.6 2.7 99.9 3.8 94.8 2.4 96.9 1.9Endrin 82.0 3.4 89.9 3.9 85.5 2.9 92.9 3.3 94.1 2.6 94.0 2.8Nitrofen 80.1 3.5 82.9 3.6 83.8 3.5 86.9 5.9 89.2 3.5 91.7 3.6Ethylan (ethyl-DDD, Perthane) 87.5 4.3 93.5 2.4 87.6 2.3 97.1 3.1 102.1 3.8 98.2 2.5Chlorfenapyr 86.7 3.4 86.2 3.0 83.2 2.3 91.3 5.3 96.6 4.3 94.8 4.5Chloropropylate 84.8 2.2 90.4 2.5 86.3 2.2 90.9 4.9 93.7 3.8 95.2 1.5Chlorobenzilate 88.6 3.6 90.7 4.4 86.2 3.6 90.9 3.5 93.6 2.5 95.1 2.9DDD-p,p′ 86.3 3.4 88.6 4.5 85.2 3.3 92.7 3.2 93.3 2.9 94.2 2.6DDT-o,p′ 83.4 3.7 88.7 2.4 85.2 3.6 89.7 5.8 93.3 3.3 94.3 2.8Diofenolan I 88.6 3.9 89.0 3.3 89.9 2.6 88.9 6.4 92.5 4.6 94.1 3.2Cyanofenphos 83.6 2.7 84.0 2.8 86.5 1.4 96.9 3.4 89.4 2.5 92.0 4.0DDT-p,p′ 84.1 6.6 85.0 5.6 84.5 5.0 91.5 5.4 91.9 4.3 95.1 4.8Diclofop-methyl 86.9 4.6 87.7 3.8 86.5 4.8 83.6 3.7 91.2 3.9 94.0 2.7Fluotrimazole 87.6 1.9 89.5 1.3 85.2 2.2 83.1 4.3 91.5 3.5 92.3 1.7Spiromesifen 85.4 4.7 88.3 3.3 82.5 2.9 100.4 3.9 94.4 2.8 95.4 3.4Endrin ketone 88.3 3.6 88.0 2.5 88.6 2.3 92.9 3.1 94.5 4.3 92.4 2.7Fenpiclonil 90.6 3.8 91.6 2.9 92.1 3.3 91.3 4.5 94.1 3.3 92.9 1.0Bifenox 83.8 2.7 85.8 2.1 86.6 2.4 83.3 2.4 88.1 2.8 92.1 1.6Tetradifon 82.7 2.7 88.3 2.3 85.9 4.4 86.3 3.3 91.6 3.3 92.5 4.9Phenothrin I 91.3 3.4 96.3 3.1 95.3 2.6 103.5 3.7 101.8 4.4 105.0 2.3Mirex 81.3 2.7 83.0 1.6 89.9 3.2 83.3 4.7 87.5 3.8 88.8 2.0Cyhalothrin (lambda) 86.7 6.9 87.3 4.9 85.0 4.3 88.6 5.3 96.3 4.5 95.6 6.6Cyfluthrin I 88.3 5.8 87.7 3.0 86.5 2.4 95.4 4.5 94.0 3.9 96.5 3.8Cypermethrin 86.5 6.3 90.4 5.5 87.6 6.9 91.5 3.2 96.2 2.8 96.3 3.4Halfenprox 83.3 7.7 87.6 5.4 82.0 4.5 85.0 3.8 86.2 3.4 88.1 2.9Boscalid 80.9 8.6 81.2 5.6 85.4 6.2 85.7 5.8 86.6 4.3 86.3 2.5Flucythrinate I 90.1 2.4 90.8 2.6 92.9 2.4 98.9 4.5 99.6 5.7 97.9 3.9
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Fenvalerate I 95.8 6.7 89.1 4.3
Esfenvalerate (Fenvalerate A-alpha) 90.6 4.3 87.8 6.0
e can see that graphitised carbon black (GCB) is very helpful inleaning up pigmented matrices. Because GCB strongly adsorbs
Please cite this article in press as: Y.-F. Li, et al., Determination of mueasy, cheap, effective, rugged and safe method with magnetic nanopChromatogr. A (2014), http://dx.doi.org/10.1016/j.chroma.2014.08.01
lanar-ring pesticides, increasing the amount of GCB will cause theoss of such pesticides. Thus, it is hard to simultaneously achieveood purification and satisfactory recovery of these pesticides withleaning by PSA and GCB.
.8 3.6 92.4 6.6 97.9 3.8 94.7 2.7
.4 4.3 98.3 4.2 95.8 2.4 94.0 1.9
To optimise the extraction efficiency of a wide range of pes-ticides and reduce or eliminate interference in the matrix, we
ltiple pesticides in fruits and vegetables using a modified quick,articles and gas chromatography tandem mass spectrometry, J.1
added bare MNPs. Comparing Fig. 4b and c, it is clear that MNPscould remove pigments from the sample matrix. It is concludedthat GCB/PSA/MNPs displayed a better clean-up performance thanGCB/PSA to remove pigment. As shown in Fig. 4d, the final
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ucumber sample purified by MgSO4/GCB/PSA/MNPs looked trans-arent; Furthermore, the chromatograms in Fig. 5 indicate thatixed sorbents (adding MNPs) provided lower level of co-extracted
nterferences. Bare MNPs exhibited a high adsorption capacityor co-extracted interferences (including pigments) in samples. A
ixture of MNPs, PSA and a reduced amount of GCB improvedurification and simultaneously resulted in satisfactory recoveryf multiple pesticides including planar-ring pesticides.
.4. Method validation
To verify the accuracy and precision of the modified method,everal basic analytical parameters were evaluated, includingecovery, linear range, limits of detection (LODs), and limits ofuantitation (LOQs). Calibration curves were calculated with aatrix-matched standard calibration in blank samples. The linear
orrelation coefficients (r2) are higher than 0.9910 in the range from to 500 �g kg−1. LODs and LOQs were estimated in the MRM modenalysis as the lowest analyte concentration that yielded signal-to-oise (S/N) ratio three and ten, respectively. The LODs and LOQsf target pesticides in matrix were analysed by the Agilent Massunter Data Acquisition. Table 2 shows the LODs and LOQs valuesere in the range of 0.03–2.17 and 0.10–7.25 �g kg−1, respectively.ecovery data were obtained for all pesticides spiked into fruitsnd vegetables at concentrations of 10, 50 and 200 �g kg−1, andach concentration was tested in five replicates. During the recov-ry study, a defined volume of pesticide-standard mixture solutionas added to the matrix. The results are summarised in Table 3.
he average recoveries of the target pesticides ranged from 71.5%o 111.7%, and the relative standard deviation was not more than0.5%. The recoveries and relative standard deviations were in lineith pesticide analysis requirements.
. Conclusions
In this work, a simple and rapid method for the analysis of mul-iple pesticides in fruit and vegetable samples was developed basedn MNP clean-up coupled with GC–MS/MS determination. Becauseost pre-treatment methods require time-consuming centrifuga-
ion or filtration, we make the method simpler, more efficientnd faster by adding MNPs to the purification process. Based onhe results presented above, the modified methodology meets theequirements for multiple pesticide determination in fruits andegetables and will have broad applications in food analysis.
cknowledgments
This research was supported by the topic “Integration andemonstration of comprehensive control technology for the pro-uction, processing and circulation safety of vegetables andoultry” in the “Demonstration of traceability control and earlyarning technology research and promotion of food safety”, which
s the scientific and technological support project of the national12th Five-Year Plan” (2012BAK17B 05).
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