Food Research International 46 (2012) 399–409
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Review
Multi-residue detection of pesticides in juice and fruit wine: A review of extraction and detection methods Baohui Jin a,⁎, Liqi Xie a, Yanfeng Guo a, Guofang Pang b a b
Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen, 518045, China Chinese Academy of Inspection and Quarantine, Jia 3 Gaobeidianbei Road, Beijing 100123, China
a r t i c l e
i n f o
Article history: Received 8 September 2011 Accepted 12 December 2011 Keywords: Review Pesticide Juice Wine Extraction Chromatography Mass spectrometry
a b s t r a c t The extensive use of pesticides in modern farming on fruit and vegetables has posed risks to public health and environment. In this study, the methods for extraction and detection of pesticides in juice and fruit wine were reviewed. Sample preparation is an important step in the analytical method, and the advantages of various new extraction techniques over the classical solvent extraction have been highlighted. Current methods involve the use of one or the combination of some of the following techniques for both the sample extraction and clean-up steps: liquid–liquid extraction, solid-phase extraction, solid-phase microextraction, stir bar sorptive extraction, matrix solid-phase dispersion and single-drop microextraction. Determination of low-level pesticide residues in juice and wine has been performed mainly by chromatographic methods employing selective detectors or, in an increasing proportion, coupled to mass spectrometry for the quantification and simultaneous identification of residues. © 2011 Elsevier Ltd. All rights reserved.
Contents 1. 2.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sample preparation techniques of juice and wine . . . . . . . . . . . . . . . . 2.1. Liquid–liquid extraction (LLE) . . . . . . . . . . . . . . . . . . . . . . 2.2. Solid phase extraction (SPE) . . . . . . . . . . . . . . . . . . . . . . . 2.3. Solid phase Microextraction (SPME) . . . . . . . . . . . . . . . . . . . 2.4. Stir bar sorptive extraction (SBSE) . . . . . . . . . . . . . . . . . . . . 2.5. Matrix solid phase dispersion (MSPD) . . . . . . . . . . . . . . . . . . 2.6. Single-drop microextraction (SDME) . . . . . . . . . . . . . . . . . . . 3. Identification and quantitation of pesticides in fruit and vegetable juices and wines 3.1. Gas chromatography (GC) . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1. Electron capture detector (ECD) . . . . . . . . . . . . . . . . . 3.1.2. Nitrogen and phosphorus detector (NPD) . . . . . . . . . . . . 3.1.3. Flame photometric detector (FPD) . . . . . . . . . . . . . . . . 3.1.4. Mass spectrometry detector (MSD) . . . . . . . . . . . . . . . 3.2. High performance liquid chromatography (HPLC) . . . . . . . . . . . . . 3.2.1. UV, DAD, fluorescence and chemiluminescence detector . . . . . 3.2.2. Mass spectrometry detector . . . . . . . . . . . . . . . . . . . 3.3. Immunoassay (IA) . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. bio-sensor method . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
⁎ Corresponding author. Tel.: + 86 755 26881671. E-mail address:
[email protected] (B.H. Jin). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.12.003
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B. Jin et al. / Food Research International 46 (2012) 399–409
1. Introduction Fruit and vegetable juice production is the fastest growing beverage industry in the world, which plays a very important role in the world's food consumption. Pesticides are used in farming on fruit and vegetables to increase yields and product quality. However, if these harmful chemicals are not degraded naturally, they will penetrate plant tissues and appear in the pulp and juice. Once present in the pulp, pesticides are difficult to completely be removed. Moreover, the concentration of pesticide residues may increase during postprocessing, where in general pesticide concentrations in processed juices are higher than that in the natural fruit (Cabras & Angioni, 2000). Compared with adults, children consume higher amounts of juices, and thus that they are more susceptible to pesticides (Topuz, Özhan, & Alpertunga, 2005). Pesticide residues in fruit wine, like those found in juice, are also introduced from planting and preservation process. Several different fungicides are widely used in the treatment of diseases of grapes for vinification such as azoxystrobin, carbendazim, cymoxanil, cyprodinil, dichlofluanid, fenhexamid, folpet, fludioxonil, metalaxyl, thiophanate methyl, penconazol, pyrimethanil, procymidone and vinclozolin (Alawi, 1995; Cabras & Angioni, 2000; Cabras, Angioni, Garau, & Minelli, 1997; Cabras, Angioni, Garau, Pirisi, & Brandolini, 1998; Cabras et al., 2001; Christensen & Granby, 2001; Di Muccio et al., 1999; Kadenczki et al., 1992; Schenck & Hennessy, 1993). The presence of pesticides has been associated with stimulating or sluggishing fermentation (Cabras et al., 1999; Girond, Blazy-Maugen, & Michel, 1989; Otero, Mañas, & Domínguez, 1993). The activity of yeast can be affected by pesticides. After fermentation, some pesticides, for example mepanipyrim, fluazinam, chlorpyrifos, were not detected in wines, but most of the pesticides can still pass from grape to must and wine (Cabras & Angioni, 2000; Navarro, Barba, Navarro, Vela, & Oliva, 2000). These pesticide residues not only result in potential health risks for the consumers, but also lead to a decrease in the wine quality. Because of the health risk of pesticide residues in juice and fruit wine, it is of particular importance to provide precise, accurate and reliable test result of residues as the scientific basis for ensuring food safety and fair practice in international trade. Pesticide residue analysis is becoming one of the most active directions in the field of analytical chemistry. Most of the traditional analysis methods of pesticide residues are applied to detection of a single component or a category of pesticides. On the contrary, multi-residue analysis method can be used to analyze not only different components of same type of pesticides, but also different components of different types of pesticides. The development of multi-residue methods represents a relatively new trend in pesticide residue analysis. 2. Sample preparation techniques of juice and wine Major techniques for extraction and concentration of pesticides in food include: (1) liquid–liquid extraction (LLE); (2) solid phase extraction (SPE); (3) solid phase micro extraction (SPME); (4) supercritical fluid extraction (SFE); (5) matrix solid phase dispersion (MSPD); (6) accelerated Solvent Extraction (ASE). In addition, several other techniques have been successfully applied to the pretreatment of pesticide residues in liquid samples (such as juices and wines), including stir bar sorptive extraction (SBSE), membrane assisted solvent extraction (MASE) and single drop microextraction (SDME). Some selected methods classified according to the sample pretreatment and detection techniques used for the determination of pesticides in juice and wine are summarized in table Table 1. 2.1. Liquid–liquid extraction (LLE) LLE, also known as solvent extraction and partitioning, is a method used to separate compounds based on their relative solubilities in two
different immiscible liquids, usually water and organic solvent. Efficiency of LLE depends on three factors: the affinity of compound for the extraction solvent, extraction volume and extraction number. LLE is a classical method for sample preparation and preconcentration. Pose-Juan, Cancho-Grande, Rial-Otero, and Simal-Gándara (2006) studied the decay rates of cyprodinil, fludioxonil, procymidone, vinclozolin in the grape juice. These pesticides were extracted with the solution of dichloromethane/acetone (4:1, v/v, 75 mL) and determined by gas chromatography mass spectrometry (GC/MS). Li and Yuan (2008) used 50 mL acetonitrile to extract fenpropathrin, bifenthrin, lambda–cyhalothrin, permethrin, fenvalerate and deltamethrin from concentrated apple juice. Sannino, Bolzoni, and Bandini (2004) established a method for determination of 24 new pesticide residues in apple puree, concentrated lemon juice and tomato puree. The solution of ethyl acetate/cyclohexane (1:1, v/v, 20 mL) was used to extract pesticides. For the determination of pesticide residues in wine, hexane (Cabras et al., 2001), ethyl acetate– petroleum ether (Cabras et al., 1997), acetone–hexane (Cabras et al., 1998), ethyl acetate–cyclohexane (de Melo Abreu, Caboni, Cabras, Alves, & Garau, 2006; González-Rodríguez, Cancho-Grande, & SimalGándara, 2009) were often selected as the extraction solution. For example, the solution of ethyl acetate/hexane (1:1, v/v) was used to extract famoxadone in wines and grape, then sample extracts were analyzed using the two chromatographic methods and a comparative study of the uncertainties was performed (de Melo Abreu et al., 2006). In a subsequent study, 11 new generation fungicides in grapes and wines were extracted with ethyl acetate/ hexane (1:1, v/v) (González-Rodríguez et al., 2009). The collected sample extract were further cleaned-up with graphitized carbon black/primary secondary amine (GCB/PSA) and good recoveries (ca. 100%) were obtained. However, LLE method is time-consuming, tedious and laborious, and requires large amounts of toxic organic solvents that pose a potential threat to human health and the environment. If there exist lots of target compounds with significant difference in polarity in samples, it would be difficult to obtain good sample preparation by using a single LLE procedure, and thus an additional solid phase extraction step are often used for further purification of sample after LLE process. Furthermore, since it is easy form emulsion during LLE process, target compounds are easy to loss in evaporation, the applications of single LLE procedure in food analysis become less and less compare the other sample extraction techniques. 2.2. Solid phase extraction (SPE) SPE is a physical extraction process. It has been proven that SPE offered several significant advantages over LLE, such as less consumption of organic solvent, shorter analysis time, no phase emulsion, higher method recovery, more efficient removal of interfering compounds. A multiresidue method based on solid-phase extraction was developed for the simultaneous determination of 50 pesticides in commercial juices (Albero, Sánchez-Brunete, & Tadeo, 2005). The extraction procedure was carried out in C18 columns. Average recoveries for all the pesticides studied were higher than 91% with relative standard deviations (RSD) lower than 9% in the concentration range of 0.02–0.1 mg/mL. Multi-walled carbon nanotubes (MWCNTs) have been used for the first time as SPE sorbents for the extraction of eight organophosphorous (OPPs) pesticides (Ravelo-Pérez, Hernández-Borges, & Rodríguez-Delgado, 2008). The results indicated mean recovery values were larger than 73% for all the pesticides and fruit juices with RSD less than 8.5%. A method for the simultaneous determination of folpet, chlorothalonil, quinomethionat, tetradifon and trifluralin in fruit juices has been developed by using C18 SPE cartridges for sample purification and preconcentration (Topuz et al., 2005). The pesticides were determined by reversed-phase
B. Jin et al. / Food Research International 46 (2012) 399–409
high-performance liquid chromatography coupled with UV-diode array detector (HPLC/DAD). He et al. (2008) developed a method for the determination of benomyl, barbendazin and thiabendazole in apple juice concentrate by SPE coupled with ion exchange chromatography (IEC). Since pesticides vary widely in polarity, it is difficult to efficiently remove the interference in samples by using one type of sorbent material for SPE. On the other hand, the mixed-mode SPE sorbent substrate can provide excellent purification with good results. Liu, Gao, Tong, and Liu (2006) established a method for the analysis of thiabendazole and barbendazim in concentrated mandarin juice. The analytes were extracted and cleaned up with mixed-mode SPE. SPE can be used to isolate analytes of interest from a wide variety of matrices, including juice and wine. It was often used combined with LLE as means for enrichment and purification. 2.3. Solid phase Microextraction (SPME) SPME, invented by Pawliszyn and co-works in 1989, is an approach to sample preparation, which integrates sampling, extraction, concentration and sample introduction to a single solvent-free step. SPME has been employed successfully in the analysis of a wide range of pollutants, such as pesticides (Popp, Kalbitz, & Oppermann, 1994), which can be performed in following three modes: direct extraction, in a headspace configuration and membrane protected approach. The SPME technique is suit for analysis pesticides from the liquid matrix, which has been developed for the determination of OPPs pesticides in wine and fruit juices (Zambonin, Quinto, De Vietro, & Palmisano, 2004). Detection limits ranged from 2 to 33 ng/mL in wine and 2 to 90 ng/mL in fruit juices. SPME in combination with sample stacking micellar electrokinetic chromatography (MEKC) was studied for the simultaneous determination of 11 multi-class pesticides residues in red wines (Ravelo-Pérez, Hernández-Borges, Borges-Miquel, & Rodríguez-Delgado, 2008) and 12 pesticides in white wines (Ravelo-Pérez, Hernández-Borges, Borges-Miquel, & Rodríguez-Delgado, 2007). polydimethylsiloxane /divinylbenzene (PDMS/DVB) fibers were found the most appropriate for the extraction of most of these pesticides. Allyloxy bisbenzo 16-crown-5 trimethoxysilane was first used as precursor to prepare the sol–gel-derived bisbenzo crown ether/hydroxyl-terminated silicone oil (OH-TSO) SPME coating (Yu, Wu, & Xing, 2004). Compared with commercial SPME stationary phases, the new coatings showed higher extraction efficiency for OPPs pesticides. The optimal extraction conditions of the coatings to OPPs were investigated by adjusting extraction time, salt addition, extraction temperature, and dilution ratios of samples with distilled water by using SPME coupled with GC/FPD. A method based on SPME and GC/FPD for the determination of OPPs pesticides in juice was described (Cai, Gong, Chen, & Wu, 2006). Three kinds of vinyl crown ether polar fibers were prepared with sol–gel process and used for the analytes. The new coatings showed higher extraction efficiency and sensitivity for OPPs pesticides compared with commercial fibers-85 μm PA and 65 μm PDMS-DVB. Specifically, the benzo-15-crown-5 coating was the most effective for the target analytes. Some SPME methods have been developed for pesticides determination for wine or juice. For example, Vázquez, Mughari, and Galera (2008) developed a SPME method for the determination of six benzoylureas in natural orange juice based on the direct immersion mode of a 60 microm PDMS/DVB fiber. The determination of benzoylureas was carried out using HPLC combined with post-column derivatization and fluorescence detection. An analytical method for determining 54 pesticide residues in different fruit juices was also developed (Cortés-Aguado, Sánchez-Morito, Arrebola, Garrido Frenich, & Martinez Vidal, 2008). The combination of a solvent and SPME extractions and GC/MS/MS reduces the 50% of the total analysis time
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required for determining routinely juices in a laboratory by a traditional strategy. At present, SPME has become a popular method for the analysis of pesticides in food matrix. The expansion of SPME applications is limited by the availability of appropriate instrumentation and coatings. Combining SPME with very specific detection techniques, and using a flash desorption injector it is possible to analyse pesticides in a short time. New coatings for the selective extraction could be another future analytical application, such as specific extraction of very complex matrices could be simplified with bioaffinity coatings. 2.4. Stir bar sorptive extraction (SBSE) SBSE is a solventless sample preparation method for the extraction and enrichment of organic compounds from aqueous matrices. The method is based on the same principles as SPME. The theory and application of SBSE methods were presented by Baltussen, Sandra, David, and Cramers (1999) in 1999. In SBSE, the coating layer of extraction phase is vitally important to performance and unfortunately only a few types of coating for SBSE have been reported. Coating materials for the stirring bar must meet the following requirements: (1) have a strong extraction capacity for analyte; (2) have good thermal stability, if using thermal desorption, the temperature will reach above 300 °C; (3) have a certain mechanical strength to withstand high-speed stirring; (4) If using solvent desorption, it should have a high solvent resistance. SPME, together with SBSE, have been combined with GC/MS/MS for analysing 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, 2,4,6tribromophenol, 2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole and 2,4,6-tribromoanisole in wine (Maggi, Zalacain, Mazzoleni, Alonso, & Salinas, 2008). SBSE and SPME methods enabled to determine the target compounds at ng/L levels. Viñas, Aguinaga, Campillo, and Hernández-córdoba (2008) compared SBSE and membrane-assisted solvent extraction (MASE) for determination of six oxazole fungicide residues in wine and juices. The best results as regards sensitivity, repeatability and analyte recovery were obtained using SBSE. The advantages of SBSE are easy to apply and automate, highly flexible, little influenced by unfavorable phase-ratio conditions, high sensitive, robust, repeatable and reproducible. On the other hand, the chief disadvantages are that it is based on a single apolar polymer (PDMS), it only can be applied to medium-high volatility and medium-high thermo-stability analytes if a thermal desorption is to be employed, only a few solvents compatible with PDMS can be adopted for analyte liquid desorption, sampling times are long when larger volumes of PDMS are used, and the cost of instrumentation is high (Majors et al., 2009). 2.5. Matrix solid phase dispersion (MSPD) MSPD is an analytical technique for the preparation and extraction of viscous samples. The technique uses bonded-phase solid supports as an abrasive to produce disruption of sample architecture and a bound solvent to aid complete sample disruption during the sample blending process. The sample disperses over the surface of the bonded phase-support material to provide a new mixed phase for isolating analytes from various sample matrices. Generally, the advantages of MSPD are: short extraction times; small amounts of sorbent and solvent needed; low costs; the possibility of simultaneously performing extraction and clean-up (Kristenson, Brinkman, & Ramos, 2006). MSPD was first applied to extract and purify drug residues in animal tissue samples (Barker, Long, & Short, 1989), and in recent years its application became popular in pesticide detection. Albero, SánchezBrunete, and Tadeo (2003) developed a multi-residue method for the determination of nine OPPs pesticides in fruit juices. The analytical procedure is based on the MSPD of juice samples on Florisil in
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Table 1 Summary of recent methodologies described for the sample pretreatment and determination of pesticide residues in juice and wine. Matrix
Pesticide
Sample treatment and clean-up technique Techniquea
Methodb DCM + CP mixture (75+25, v/ GC/MS v) EA + CYH(50+50, v/v) LC/MS/ MS
cyprodinil, fludioxonil, procymidone, vinclozoline
LLE
concentrated lemon juice
24 pesticides
LLE
wine
famoxadone
LLE
EA+Hex (50+50, v/v)
wine
27 pesticides
LLE
ACN
LLE
1% HOAc in ACN
HF-LLLME
phenetole; donor phase: 1M HCl; acceptor solution: 0.1M NaOH; ACN, Florisil,
conceutrate juice
LLE+SPE
wine
fenpropathrin, decamethrin, Lambda-cyhalothrin, permethrin, fenvalerate, decamethrin 11 pesticides
fruit juices
90 pesticides
LLE+SPE
carrot juice
Ref.e
LOQ ≤ 14.9 μg/L
Pose-Juan et al. (2006)
Sannino et al. (2004) 76–106 (15), except LOQ: 2–20 μg/kg imidacloprid for 62– 83 91–115 (≤11.7); 84– LOD (GC-ECD): 60 μg/L; LOD (GC-MS): de Melo Abreu et al. (2006) 108 (≤ 6.8) 20 μg/L
GC/ECD and GC/ MS LP/GC/ MS GC/MS/ MS HPLC/UV
55.0–112.2, SD: 2.27– LOD b 1.0 μg/L 16.97 88.3–119.1 (4.9-8.4) LOD b 8.8 μg/mL
GC/ECD
84.2–102.4 (1.1–9.2)
LOD: 2.5–10 μg/kg
Li and Yuan (2008)
Ca. 100 (≤16)
LOD ≤ 10 μg/kg or μg/L
70.4–108.5 (≤ 20)
LOQ ≤ 5 μg/L
LOD: 2–5 μg/L
González-Rodríguez et al. (2009) Romero-González, Garrido Frenich, and Martínez Vidal (2008) Dong et al. (2009)
EA + Hex (1+1, v/v), GCB/PSA GC/MS SPE 1% HOAc in ACN, Oasis, Strata- UPLC/ X and C18 cartridges MS/MS
52–121 (4–19)
LOQ: 1.3–19.0 μg/kg
Cunha et al. (2009) Yin (2008) Wu and Hu (2009)
LLE+SPE
ACN, Florisil,
GC/μECD
80.5–104 (b 6)
LLE+SPE
ACN, PSA cartridge,
GC/MS
82–110 (2.9–15.5)
37 pesticides
SPE
Oasis cartridge + florisil cartridge
76–120 (3–8)
LOD ≤ 12 μg/L
Jiménez et al. (2001)
50 pesticides ethoprophos, diazinon, chlorpyriphos-methyl, fenitrothion, malathion, chlorpyriphos, fenamiphos, buprofezin
SPE SPE
C18 cartridge Multi-walled carbon nanotubes
GC/ECD and GC/ NPD GC/MS GC/NPD
>91 (b 9) ≥73 (≤ 8.5)
LOD: 0.1–4.6 μg/L LOD: 1.85–7.32 μg/L
Albero et al. (2005) Ravelo-Pérez, HernándezBorges, and RodríguezDelgado (2008)
folpet, chlorothalonil, quinomethionat, tetradifon, trifluralin apple juice benomyl, carbendazim, thiabendazole concentrate concentrated thiabendazole, carbendazim mandarin juice concentrated 105 pesticides apple juice wine 19 pesticides
SPE
C18 cartridge
93.8–99.5 (≤3.4)
LOD: 0.5–1 μg/kg
Topuz et al. (2005)
94.2–100.4 (b 4.2)
LOD: 4 μg/kg
He et al. (2008)
80.8–87.7 (7.38 )
LOD: 20 μg/kg
Liu et al. (2006)
SPE, MLLE
SUPELCLEAN LC-18 cartridge, EA
GC/MS
wine
46 pesticides
SPE
Oasis HLB cartridges
wine
2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, 2,4,6-tribromophenol, 2,4,6-trichloroanisole, 2,3,4,6tetrachloroanisole, 2,4,6-tribromoanisole hymexazol, drazoxolon, vinclozolin, chlozolinate, oxadixyl, famoxadone 18 organic contaminant
SBSE and SPME
PDMS
HPLC/ MS/MS GC/MS/ MS
SBSE
PDMS
SBSE and MASE
PDMS (SBSE); dense PP (MASE)
fruit vegetable juices wine
chlorothalonil, fenpropathrin, cyhalothrin, cypermethrin, fenvalerate, deltamethrin and 59 pesticides
LLE+SPE
97–109 (5.5–15.1)
Detection Limits
juices apple, grape, orange and pineapple fruit juices juice
wine and juice Brazilian sugarcane juice
SPE SPE SPE
HPLC/ DAD SCX SPE column HPLC/ DAD mixed-mode SPE HPLC/ DAD celite chromatographic column GC/MS
UPLC/ DAD GC/MS
Wang et al. (2006)
70–110 (3.0–14.9)
Hu et al. (2003)
SPE: 77.8–109.1 (b 10); MLLE: 83.3– 116.7 (b14) 70–110 (b20)
LOD(SPE): 1–10 μg/kg, LOQ (SPE): 5– 50 μg/kg; LOD (MLLE): 20–100 μg/kg, LOQ (MLLE): 60–300 μg/kg LOD: 0.3–3 μg/L, LOQ: 1–10 μg/L
SBSE: (0.23–13.34); SPME: (0.01–14.21)
LOD (SBSE): 10–710 μg/L, LOD (SPME): Maggi et al. (2008) 220–880 μg/L
83–113 (≤7.9)
LOD: 0.05–2.5 μg/L; LOQ 0.15–8.0 μg/L
Viñas et al. (2008)
LOD (SBSE): 0.002–0.71 μg/L; LOD (MASE): 0.004–0.56 μg/L;
Zuin et al. (2006)
Wang et al. (2007)
Economoul et al. (2009)
B. Jin et al. / Food Research International 46 (2012) 399–409
grape juice
60 pesticides concentrated apple juice natural coconut salicylic acid, indole-3-acetic acid, (±) abscisic acid, juice (±) jasmonic acid
Analysisc Recovery (RSD), %
SBSE: 0.2–55.3 (0.3– 19.2); MASE: 13.6– 103.1 (2.6–18.4) wine wine and juices
13 insecticides and fungicides fruit phorate, diazinon, methyl-parathion, fenitrothion, malathion, fenthion, ethyl-parathion, methidathion
SPME SPME
PDMS PA
GC/MS GC/MS
MEKC/ DAD MEKC/ DAD
Grapefruit: 21–102; lemon juice: 5–83; wine: 62–104
Urruty and Montury (1996) LOD (wine): 2–33 μg/L; LOQ (wine): 7– Zambonin et al. (2004) 109 μg/L; LOD (juice): 2–90 μg/L; LOQ (juice): 7–297 μg/L; LOQ: 54–113 μg/L Ravelo-Pérez et al. (2007)
90–107
LOD: 0.049–1.69 mg/L
wine
12 pesticides
SPME
PDMS/DVB
wine
11 pesticides
SPME
PDMS/DVB
wine apple juice
12 pesticides 8 pesticides
SPME SPME
PDMS PA and PDMS/DVB
GC/TSD GC/FPD
(≤5) >55.3 (.1%–8.9)
LOD: 0.00–0.38 μg/L LOD: 0.003–0.09 μg/kg
juice
dichlorvos, phorate, dimethoate, diazinon, methyl parathion, malathion, fenthion, chlorpyrifos, ethion, triazophos
SPME
GC/FPD
80.1–95.6 (0.3–9.1)
LOD: 0.003–1.0 μg/kg
juice
cyprodinil, cyromazine, pyrifenox, pirimicarb, pyrimethanil
SPME
sol–gel-derived bisbenzo crown ether/hydroxylterminated silicone oil (OHTSO) PDMS/DVB
CE/UV
5–36 (6–13)
LOD: 3.1–47 μg/L
orange juice
diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, lufenuron, flufenoxuron 54 pesticides
SPME
PDMS/DVB
85–110 (1.8–7.4)
LOQ: 20–40 μg/kg
SPME
PDMS/DVB
HS-SPME
CAR/PDMS
GC-MS: 73–96 (b 25); GC-MS/MS: 71-108, (b17) 86.3–105.0 (1.6–7.4)
GC-MS: LOD 0.7–19.6 μg/L, GC-MS/MS: Cortés-Aguado et al. (2008) LOD: 0.01–16.7 μg/L
ethephon
HPLC/ FLD GC/MS and GC/ MS/MS GC
diazinon, parathion methyl, fenitrothion, parathion, bromophos, quinalphos, carbophenothion, phosalone carbofuran, monuron, pirimicarb, monolinuron, diuron, diethofencarb, benfuracarb, carbosulfan
SPME
PA
GC/NPD
LOD: 400–4100 μg/L
Kong (2009)
SPME
PDMS/DVB; Carbowax/ templated resin; polyacrylate
69.2–103.2 (0.98– 4.8) 25–82 (1–17)
LOQ: 5–50 μg/L
Sagratini et al. (2007)
87–96 (1.4–9.9)
LOD: 7–25 μg/kg
Li et al. (2005) Hu, Yu, et al. (2004) Chu et al. (2005) Albero et al. (2004)
crude mango pulp apple juice concentrate fruit juice
Li and Zheng (2007)
concentrated apple juice apple juice apple juice carrot, grape, multivegetable juices fruit juices
methamidophos, omethoate, malathion, parathion, dichlorvos 106 pesticides 266 pesticides 15 herbicides
MSPD
Polygoprep100-50 C18
HPLC/ MS; LC/ QIT-MS GC/FPD
MSPD MSPD MSPD
diatomaceous earth diatomaceous earth Florisil
GC/MS GC/MS GC/MS
70–110 (1.62–18.4) 70.8–116.8 (b 24) 82–115 (b10)
LOD: 3.0–18.0 μg/kg LOD: 0.1–1.6 μg/L
10 pesticides
MSPD
Florisil
GC/ECD
>74 (1–12)
LOD: 1–5 μg/kg
wine
procymidone, pentachloroaniline and methylpentachlorophenylsulfide 37 pesticides
MSPD
Florisil
GC/ECD
82.4–93.7 (b8)
LOD: 0.1–0.4 μg/L
MSPD
diatomaceous earth
GC/MS
12 pesticides
MSPD
diatomaceous earth
ethoprophos, diazinon, parathion methyl, fenitrothion, malathion, isocarbophos, quinaphos Dichlorvos, phorate, fenitrothion, malathion, parathion, quinalphos 2,4,6-trichloroanisole, 2,4,6-tribromoanisole
SDME
toluene
HPLC/ MS/MS GC/FPD
70.4–108.3 (2.1– 24.9) 71–118 (5–15)
SDME
toluene
GC/FPD
SDME
1-octanol
GC/ECD
MASE
Nonporous PP
GC/MS
DLLME
tetrachloroethane
concentrated apple juice fruit juice orange juice fruit juice wine
wine and apple parathion-methyl, fenitrothion, malathion, fenthion, juice bromophos, bromophos-ethyl, fenamiphos, ethion fruit juice carbaryl, triazophos
76.2–108.0 (4.6– 14.1) 77.7–113.6 (1.7–10) TCA: 55.4–97.0 (12.4); TBA: 73.2– 109.1 (16.7) 47–100 (4–22)
Hernández-Borges, Cifuentes, García-Montelongo, and Rodríguez-Delgado (2005) Vázquez et al. (2008)
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fruit juices
Ravelo-Pérez, HernándezBorges, Borges-Miquel, and Rodríguez-Delgado (2008) Hu, Liu, Zhou, and Guan (2006) Cai, Gong, Chen and Wu (2006) Yu et al. (2004)
Tadeo and Sánchez-Brunete (2003) Zhu et al. (2007) Hu, Chu, et al. (2004)
LOD: 0.01–0.94 μg/L, LOQ: 0.03– 3.12 μg/L LOD b 5 μg/L
Radušić et al. (2009)
LOD : 0.21–0.56 μg/L
Xiao et al. (2006)
Zhao et al. (2006)
LOD (TCA): 8.1 ng/L; LOD (TBA): 6.1 Martendal et al. (2007) ng/L; LOQ (TCA): 26.9 ng/L; LOQ (TBA): 20.3 ng/L; LOD: 1–23 ng/L Schellin et al. (2004) Fu et al. (2009) 403
(continued on next page)
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Table 1 (continued) Matrix
Pesticide
Sample treatment and clean-up technique Technique
a
Method
Analysisc Recovery (RSD), %
Detection Limits
80.4–117.9 (1.38– 2.74) 91–115
LOD: 12.3–16.0 ng/L (0.006–0.020 ppm) LOD: 50 μg/kg for red wine and 25 μg/ kg for white wine LOD: 0.15 μg/L for carbaryl; 1.2 μg/L, for metolcarb LOQ: 5–20 μg/L LOD: 0.08±0.03 μg/L
propamocarb
——
——
apple juice
Carbaryl and metolcarb
ELISA
——
ELLSA
> 70 (2.58–12.49)
fruit juice fruit juice
imidacloprid thiabendazole
ELISA ELISA
—— ——
ELLSA ELLSA
juice
paraxon, carbofuran
biosensor
electrode
EC
94.2–113.2 (b20) 81.9–123.6 (9.9– 19.3) 93.3–109.9 (6)
fruit juice
carbaryl, 3,5,6-trichloro-2-pyridinol (TCP)
immunosensor quartz crystal microbalance
fruit juice
thiourea
catalytic kinetic method FL probe
a b c
differential pulse polarographic (DPP)
EC
the oxidation of Janus green by UV potassium iodate in hydrochloric acid media acetylcholinesterase FL saturated calomel electrode
EC
95.4–101.0 (1.68– 2.56)
Sun et al. (2010) Watanabe et al. (2007) Blažková, Rauch, and Fukal (2010) Albareda-Sirvent et al. (2001)
LOD: 2.12×10− 10 M (0.047 μg/kg) for carbofuran and 6×10− 10 M (0.165 μg/ kg) for paraoxon LOD: 11 μg/L for carbaryl and 7 μg/L for March et al. (2009) TCP LOD: 8 μg/L Abbasi et al. (2010)
93.2–118 (1.95–5.53) LOD: 5–50 μg/L 97.5–99.4 (3.64)
Taylor et al. (2004)
−7
LOD: 1.48×10 mol/L, LOQ: 4.93×10− 7 mol/L
Jin et al. (2004) Mercan et al. (2007)
HF-LLL, hollow fiber-based liquid–liquid–liquid microextraction. ACN, acetonitrile; DCM, dichloromethane; Hex, hexane; HOAc, acetic acid; EA, ethyl acetate; CYH, cyclohexane; CP, acetone; PDMS, polydimethylsiloxane; DVB, divinylbenzene; PA, polyacrylate; PP, polypropylene. LP, low-pressure; QIT, quadrupole ion trap; TSD, Thermionic Sensitive Detection; EC, electrochemical technology.
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wine
HPLC/ FLD LC/MS
cole juice, Carbofuran, carbaryl, paraoxon, dichlorvos cabbage juice orange juice pymetrozine
Ref.e
b
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small glass columns and subsequent extraction with ethyl acetate assisted by sonication. Residue levels were determined by GC/NPD. Several factors that affect in conducting MSPD extractions were investigated (Barker, 2007), including (1) the effect of average particle size diameter. (2) Non-end-capped vs. end-capped materials or materials having a range of carbon loading (8–18%). (3) The character of the bonded-phase. Depending on the polarity of the phase chosen, rather dramatic effects on the results may be observed. (4) The use of underivatized silica or other solid supports. (5) The best ratio of sample to solid support material. (6) Chemical modification of the matrix or matrix solid support blend. (7) The optimum choice of elution solvents and the sequence of their application to a column. (8) The elution volume. (9) The effect of the sample matrix itself. Albero, Sánchez-Brunete, Donoso, and Tadeo (2004) developed a MSPD method for the rapid multiresidue determination of pestcides in multivegetable juices. After the optimization of different parameters such as the type of adsorbent and the extraction solvent, the recoveries obtained ranged from 81 to 115% with RSD equal to or lower than 10%. A multi-residue method was applied for the analysis of 106 multiclass pesticides in apple juice (Hu et al., 2004). The determination procedure was based on MSPD of juice on diatomaceous earth in a glass column and subsequent extraction with a mixture of hexane/dichloromethane (1:1, v/v) at a flow rate of 5 mL/min. The analytes were determined by GC/MS. A MSPD method was developed to extract 266 pesticides from apple juice samples prior to GC/MSD determination (Chu, Hu, & Yao, 2005). In this study, 10 g sample was mixed with 20 g diatomaceous earth. Radišić, Grujić, Vasiljević, and Laušević (2009) developed a LC/MS/MS method for the analysis of 12 pesticides in fruit juices. Extracts were obtained by MSPD using diatomaceous earth as dispersant and dichloromethane as eluent. Recoveries were in the range from 71% to 118% and method repeatability ranged between 5% and 15%. Even if MSPD process has some limitations and cannot be completely automatized, because it requires the blending in a mortar with a pestle by an operator, the literature has been showing a great interest in this extraction technique. Besides all the well-known advantages, this technique presents potential improvements, mainly based on the development of more specific sorbents for blending the samples, and process miniaturization (Capriotti et al., 2010). 2.6. Single-drop microextraction (SDME) SDME is a new method of sample preparation. It is a miniaturized implementation of conventional LLE in which only microliters of solvents are used instead of several hundred milliliters in LLE (Hou & Lee, 2004). Jeannot and Cantwell (1997a) first applied SDME to the determination of free (unbound) progesterone in the presence of a binding protein. In 1997 Jeannot and Cantwell (1997b), and He and Lee (1997) independently introduced a simpler kind of microextraction in which an organic drop hangs from the tip of a GC syringe needle. In recent years, SDME has greatly been developed and extensively used for the analysis of pesticide residues in juice and wine. Zhao, Han, Jiang, Wang, and Zhou (2006) developed a method for the determination of OPPs pesticides in orange juice. SDME parameters, such as organic solvent, drop volume, agitation rate, extraction time and salt concentration were optimized. The orange juice was extracted by SDME and analyzed by GC/FPD. Mean relative recoveries for all test pesticides were in the range between 76.2% and 108.0%. Xiao, Hu, Yu, Xia, and Jiang (2006) established a SDME-GC/FPD method for the analysis of OPPs in fruit juice. The parameters affecting the SDME performance were studied and optimized. Two types of SDME mode, static and cycle-flow SDME were evaluated. Compared to cycle-flow mode, the static SDME procedure provided more sensitive analysis of the target analytes. Martendal, Budziak, and Carasek (2007) presented a method for the determination of 2,4,6-
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trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA) in wine. Headspace SDME was used for the extraction and preconcentration of the analytes. Excellent detection limits of 8.1 and 6.1 ng/L were achieved for TCA and TBA, respectively. SDME has the advantage of high extraction speed. It uses inexpensive apparatus and virtually eliminates solvent consumption. SDME can find use in most sample preparation procedures, with analytes ranging from volatile organic compounds, through polar and nonpolar semivolatiles, to ionic compounds and metal ions, as long as suitable solvents and equipment are available. A disadvantage of SDME is a lack of precision, which may be caused by the completely manual operation, from fiber preparation and conditioning to the handling of extract. In addition, there are many other preparation techniques applied to pesticide residues in juice and wine, such as Accelerated Solvent Extraction (ASE) (Wang, Peng, & Li, 2008), Ultrasound-assisted Extraction (UAE) (Ramos, Rial-Otero, Ramos, & Capelo, 2008), Membrane Assisted Solvent Extraction (MASE) (Zuin et al., 2006), which were not reviewed in this paper because of fewer applications. 3. Identification and quantitation of pesticides in fruit and vegetable juices and wines Different detection techniques are used for determination of pesticide residues in wine and juice. In recent years, gas chromatography (GC), gas chromatography mass spectrometry (GC/MS) and gas chromatography tandem mass spectrometry (GC/MS/MS) had made a progress in field of monitoring pesticides because of the high separation power, selectivity and identification capabilities of MS. The variety of sensitive detectors coupled with GC such as electron capture detector (ECD), nitrogen phosphorus detector (NPD), flame ionization detector (FID), flame photometric detector (FPD) improved the detection and quantification procedures of pesticide residues. Besides GC/MS methods, there are other traditional quantification methods like high performance liquid chromatography (HPLC), liquid chromatography mass spectrometry (LC/MS) and liquid chromatography tandem mass spectrometry (LC/MS/MS). Due to its advantages of fast, economic, and at least as sensitive as chromatographic techniques, immunochemical methods have also gained a place in the analytical benchtop as alternative or complementary methods for routine pesticide analysis. 3.1. Gas chromatography (GC) GC is an analytical technique for separating compounds based primarily on their volatilities. Since the introduction in the late 1960s of GC and the inherent remarkable feature to perform on a packed column multi-residue analysis, the technique became rapidly adopted. Further important developments such as capillary columns and sensitive and selective detectors significantly enlarged the number of pesticides efficiently analyzed in one run (Hogendoorn & van Zoonen, 2000). 3.1.1. Electron capture detector (ECD) The ECD is used for detecting electron-absorbing components (high electronegativity) such as halogenated compound in the output stream of a gas chromatograph. Tadeo and Sánchez-Brunete (2003) developed a multiresidue method for the analysis of pesticides in fruit juices. Residue levels were determined by GC/ECD. Recoveries obtained for pesticides in different fruit juices at various fortification levels were higher than 74%, with RSD ranged between 1 and 12%. Dong, Luo, Xie, and Wang (2009) developed a multi-residue determination method for chlorothalonil and five pyrethroids in carrot and carrot juice. Chlorothalonil and five pyrethroids were separated by DB-5 capillary vessel column, and quantitatively detected by GC/μECD. The recovery
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range was between 80.5% and 104% with coefficient of variation less than 6%. X.L. Zhu et al. (2007) developed a method based on MSPD for the determination of procymidone, pentachloroaniline and methyl-pentachloro-phenylsulfide in wine. The analysis of samples was accomplished using GC/ECD. The recovery of the method was in the range from 82.4 to 93.7% with RSD lower than 8%. Anli, Vural, Vural, and Gucer (2007) presented a GC method for the determination of the residue levels of chlorpyrifos and chlorpyrifosmethyl in wine. The samples were diluted with water and extracted by SPME. NDP and ECD were used to identify and quantify the pesticides. 3.1.2. Nitrogen and phosphorus detector (NPD) The NPD (sometimes called the thermionic detector) is a very sensitive and specific detector that responds to nitrogen and phosphorous compounds. It is based on the FID but differs in that it contains a rubidium or cesium silicate (glass) bead situated in a heater coil, a little distance from the hydrogen flame. A method for the determination of eight OPPs in apple juice concentrate was developed by using fiber SPME coupled with GC/NPD (Kong, 2009). The average recoveries for all the pesticides were in the range from 69.2% to 103.2% with RSD of 0.98%–4.8%. RaveloPérez, Hernández-Borges, & Rodríguez-Delgado, 2008 also developed a method for the determination of eight OPPs pesticides from different commercial fruit juices by using SPE and GC/NPD techniques. A method for multi-residue analysis of several common pesticides in wine samples was proposed (Jiménez, Bernal, del Nozal, Toribio, & Arias, 2001), which combined SPE on polymeric cartridges with GC determination using ECD and NPD. 3.1.3. Flame photometric detector (FPD) The determination of sulfur or phosphorus containing compounds is the job of the FPD. Li, Hu, Wu, Zhang, and Wu (2005) developed a MSPD-GC/FPD method for simultaneous detection of 5 OPPs residues in concentrated apple juice. Xiao et al. (2006) established a SDME procedure for the analysis of OPPs in fruit juice by GC/FPD. Cai et al. (2006) described a method based on SPME and GC/FPD for the determination of OPPs in apple juice. The apparent recoveries of spiked apple juice were determined to be over 55.3% and the limits of detection were in the range between 0.003 and 0.09 ng/g for the OPPs studied. 3.1.4. Mass spectrometry detector (MSD) 3.1.4.1. Gas chromatography mass spectrometry (GC/MS). GC/MS is irreplaceable in pesticide analysis. The key characteristics of GC/MS in pesticide analysis are its selectivity and sensitivity, but other important features will be considered in detail in the specific sections on identification and quantitative analysis. Major limitations in the use of GC/MS depend on GC limits. Thus, very polar and thermally labile pesticides are not suitable for GC separation and cannot be analyzed by GC/MS. Hu et al. (2003) presented a GC/MS method for the determination of 105 pesticide residues in concentrated apple juice samples. Compounds were identified and determined according to their retention times and characteristic ions. The linear ranges for most pesticides are 0.05–10 mg/kg. Over 90% of the compounds have mean recoveries of 70%–110% at a spiked level of 0.2 mg/kg. Hu et al. (2004) also established a GC/MS method for the determination of 22 organochlorine pesticides and 15 pyrethroid pesticides residues in apple juice samples. Further confirmation of the pesticide identities was performed by the dual-column method. Wang, Zhang, Chu, and Wang (2006) developed a GC/MS procedure for the determination of multiple pesticide residues in concentrated fruit and vegetable juices. Retention time locking (RTL) pesticide database was used to simplify the editing of SIM ion groups and eliminate the tedious retention
time updating process upon instrument maintenance. Large volume injection of samples with a temperature programmed vaporizer (PTV) system was investigated. Wang, Luan, Wang, Jinag, and Pan (2007) developed a multi-residue method for confirmation and quantitation of 19 pesticides in red grape wine. LLE and SPE were compared and GC/MS was used for the detection. Nguyen, Yun, and Lee (2009) developed an analytical method for measuring 118 pesticides in vegetable juice. The extraction of pesticides was carried out with MSPD method, and determination was performed using GC/MS and LC/ESI-MS/MS. A fast method using low-pressure gas chromatography coupled to mass spectrometry (LP-GC/MS) was implemented and optimized to yield a complete separation of 27 representative pesticides in grapes, musts and wines (Cunha, Fernandes, Alves, & Oliveira, 2009). Several LP-GC/MS conditions such as column temperature, injection conditions, flow rate, MS conditions and matrix effects were evaluated to achieve the fastest separation with the highest sensitivity in MS detection. Acceptable recoveries for nearly all pesticides were achieved with good repeatability. Eight OPPs pesticides in aqueous samples were extracted by means of MASE (Schellin, Hauser, & Popp, 2004). The technique was fully automated and successfully combinable with large volume extraction and GC/ MS. Detection limits in the ng/L level were achieved using large volume injection with the injecting volume of 100 μL. The recovery values ranged from 47 to 100% and the RSD was between 4 and 12%. Microporous membrane LLE was coupled on-line with GC/FID and GC/MS for the determination of pesticides in wine (Hyötyläinen, Lüthje, Rautiainen-Rämä, & Riekkola, 2004). LODs ranged from 0.05 to 2.3 μg/L and LOQs were in the range between 0.2 and 7.5 μg/L for all the analytes using FID as detector. LODs in the range of 0.03–0.4 μg/L and LOQs of 0.3–3.5 μg/L were achieved with MS detection. 3.1.4.2. Gas chromatography tandem mass spectrometry (GC/MS/MS). When a second phase of mass fragmentation is added, for example using a second quadrupole in a quadrupole instrument, it is called tandem MS (MS/MS). MS/MS can sometimes be used to quantitate low levels of target compounds in the presence of a high sample matrix background. Yin (2008) established a GC/MS/MS method for the determination of 60 pesticide residues in concentrated apple juice. The recovery ranged from 55.0% to 112%. Cortés-Aguado et al. (2008) proposed a new vanguard–rearguard analytical method for determining 54 pesticide residues in different fruit juices. For that, in a first step, a fast screening (vanguard) method is applied for detecting those samples containing pesticides at concentrations above a pre-established cut-off value. In a second step, those samples are re-analyzed by a conventional pesticide residue (rearguard) method that confirms the presence of the pesticides and quantifies them. The instrumental determination is carried out by GC/MS in a full scan acquisition mode for the screening method and a MS/MS acquisition mode for the quantifying/confirming method. 3.2. High performance liquid chromatography (HPLC) HPLC typically utilizes different types of stationary phases, a pump that moves the mobile phase(s) and analyte through the column, and a detector that provides a characteristic retention time for the analyte. Analyte retention time varies depending on the strength of its interactions with the stationary phase, the ratio/composition of solvent(s) used, and the flow rate of the mobile phase. With HPLC, a pump (rather than gravity) provides the higher pressure required to propel the mobile phase and analyte through the densely packed column. The increased density arises from smaller particle sizes. This allows for a better separation on columns of shorter length when compared to ordinary column chromatography.
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3.2.1. UV, DAD, fluorescence and chemiluminescence detector HPLC methods for the determination of pesticide residues in juice and wine could employ UV absorption, UV diode array, fluorescence (FL) and chemiluminescence (CL) detection. Topuz et al. (2005) developed a method for the simultaneous determination of five pesticides in fruit juices. The pesticides were separated and quantified by reversed-phase HPLC with UV-diode array detection at 220 and 260 nm. Recoveries from spiked apple, cherry juices, ranged from 93.8% to 99.5% and RSDs were less than 3.4% in the concentration range from 1 to 16 μg/kg. A dispersive liquid–liquid microextraction (DLLME) coupled with HPLC/FL has been developed to determine carbaryl and triazophos residues in fruit juice samples (Fu et al., 2009). RSDs varied from 1.38% to 2.74%. Wu and Hu (2009) developed a method of hollow fiber-based liquid–liquid–liquid microextraction (HF-LLLME) combined with HPLC/UV detection for the determination of four acidic phytohormones in natural coconut juice. The detection limits (S/N = 3) were 4.6, 1.3, 0.9 and 8.8 μg/mL for SA, LAA, ABA and JA, respectively. RSDs were 7.9, 4.9, 6.8% at 50 ng/mL level for SA, IAA, ABA and 8.4% at 500 μg/mL for JA, respectively. 3.2.2. Mass spectrometry detector The powerful features of LC/MS, such as high efficient separation, identification, and quantification of polar analytes, make this technique very attractive to the field of pesticide residue analysis. In particular, it has been shown that, in combination with tandem mass spectrometry (ion trap or triple quadrupole), LC is a very sensitive technique to reveal pesticide residues in juice and wine. Taylor, Hird, Sykes, and Startin (2004) reported a LC/MS method for the determination of propamocarb residues in wine. LC was performed with a mobile-phase gradient and detection was by electrospray mass spectrometry in a positive ionization mode. Recovery of propamocarb hydrochloride from wine spiked before dilution was in the range from 91 to 115%. Economoul, Botitsi, Antoniou, and Tsipi (2009) reported a multi-residue LC/MS/MS method for detection, confirmation and quantification of forty-six pesticides and transformation products in wines. Limits of detection were in the range from 0.0003 to 0.003 mg/L and limits of quantification ranged from 0.001 to 0.01 mg/L. The average recoveries were in the range between 70 and 110% for most of the compounds tested. Sagratini, Mañes, Giardiná, Damiani, and Picó (2007) developed an analysis method to detect carbamates and phenylurea pesticide residues in fruit juices by using SPME coupled with LC/MS and LC/QIT-MS. The mass spectrometry analyses were carried out by using electrospray ionization (ESI) source operating in the positive mode both for single quadrupole and for QIT mass analysers, operating in selected ion monitoring (SIM) and in multiple reaction monitoring (MRM) modes, respectively. Radušić, Grujić, Vasiljević, and Laušević (2009) developed a HPLC/ MS/MS method for the analysis of pesticides in fruit juices. Significant matrix effects observed for most of the pesticides tested were eliminated by using matrix-matched standards. Recoveries were in the range from 71 to 118%. Low limits of detection (0.01–0.94 ng/mL) and quantification (0.03–3.12 ng/mL) were readily achieved for all tested pesticides. 3.3. Immunoassay (IA) IA provides rapid, sensitive and cost effective analysis for a variety of pesticide residues. The main disadvantage is that only one compound at a time can be determined. The usefulness of these techniques is experienced during screening analyses when a large number of samples have to be analyzed in parallel for a single analyte within a short time. Sun, Dong, Yang, and Wang (2010) described a direct competitive enzyme linked immunosorbent assay (ElISA) in multi-enzyme tracers format for the simultaneous analysis of carbaryl and metolcarb in fruit juices. The limits of detection of carbaryl and metolcarb were
407
0.15 μg/L and 1.2 μg/L, respectively. Recoveries of spiked samples were higher than 70%. An ELISA was used to directly determine residual imidacloprid in fruit juices (Watanabe, Baba, Eun, & Miyake, 2007). The ELISA enabled imidacloprid to accurately determine down to about 5 μg/L in apple and grape juice samples and down to about 20 μg/L in orange juice sample.
3.4. bio-sensor method A biosensor is an analytical device which converts a biological response into an electrical signal. Biosensors are potentially useful as pre-screening methods for direct field use. The general requirements for a routinely used biosensor include low cost, short assay time and limited sample pre-treatment. Albareda-Sirvent, Merkoci, and Alegret (2001) presented a design of biosensor strips for pesticide analysis. The biosensors integrate a photolithographic conducting copper track, graphite-epoxy composite applied by screen-printing and enzyme (AChE or BChE) immobilised manually by crosslinking with glutaraldehyde. Detection limits in the level of 10 − 10 to 10 − 11 M pesticides have been achieved in standard solutions. Pesticide analysis has been realized on spiked real samples of fruit juice, with recovering percentages close to 100%. March, Manclús, Jiménez, Arnau, and Montoya (2009) developed a quartz crystal microbalance (QCM) immunosensor for the determination of the insecticide carbaryl and 3,5,6-trichloro-2pyridinol. The detection was based on a competitive conjugateimmobilized immunoassay format using monoclonal antibodies. Hapten conjugates were covalently immobilized, via thioctic acid self-assembled monolayer, onto the gold electrode sensitive surface of the quartz crystal. This covalent immobilization allowed the reusability of the modified electrode surface for at least one hundred and fifty assays without significant loss of sensitivity. Other techniques have also been proposed to determine pesticide residue contents in juice and wine, such as kinetic spectrophotometric method (Abbasi, Khani, Hosseinzadeh, & Safari, 2010), fluorescence (Jin et al., 2004), differential pulse polarography (Mercan, Yilmaz, & Inam, 2007), etc. In fact, GC, in combination with selective detectors, mainly NPD, ECD, FPD or MS, is still the most common technique for the determination of pesticide residues. Particularly, GC/MS methods for pesticide residue analysis in wine and juice are commonly used because fast pesticide determination is frequently required, which can identify unknown pesticides from the combination of the retention time and mass spectrum for each compound it analyzes.
4. Conclusion To sum up, in recent years there has been considerable improvement in pesticide residues analysis. Various pretreatment methods and detection techniques have been applied for pesticide residues analysis in juice and wine. But there is also a growing need for more efficient, rapid, and inexpensive methods for the analysis of pesticide residues in juice and wine as the demand for residue-free foodstuffs increases. Some improvements in the extraction-cleanup steps have been made, and dramatic changes are occurring in the resolutiondetermination steps. Such techniques as GC or LC are becoming commonplace; SPE and SPME are developing rapidly; improved selective detectors have been added to the market; GC/MS, LC/MS, and MS/MS are continuing to grow in acceptance; and many applications of immunoassay and biosensor in residue analysis have been reported. More importantly, high throughout analysis techniques for hundreds of different kinds of pesticides, using rapid, semiquantitative screens and more rigorous methods for those samples which screen positive, have merit (Pang et al., 2006).
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