|A novel chemiluminescence assay of organophosphorous pesticide quinalphos residue in vegetable with luminol detection.|
|Jump to Full Text|
|PMID: 20576096 Owner: NLM Status: PubMed-not-MEDLINE|
|BACKGROUND: Organophosphorous pesticides are the most popular pesticides used in agriculture. As acetylcholinesterase inhibitors, organophosphorous pesticides are toxic organic chemicals. The control and detection of organophosphorous pesticide residue in food, water, and environment therefore plays a very important role in maintaining physical health. A sensitive, rapid, simple chemiluminescence(CL) method has been developed for the determination of quinalphos based on the reaction of quinalphos with luminol-H2O2 in an alkaline medium. The method has been applied to detection of quinalphos in vegetable samples with satisfactory results.
RESULTS: The CL method for the determination of organophosphorous pesticide quinalphos is based on the phenomenon that quinalphos can apparently enhance the CL intensity of the luminol-H2O2 system. The optimal conditions were: luminol concentration 5.0 x 10-4 mol/L, H2O2 concentration 0.05 mol/L.pH value 13. In order to restrain the interference from metal ions, 1.0 x 10-3 mol/L of EDTA was added to the luminol solution. The possible mechanism was proposed.
CONCLUSION: Under the optimum reaction conditions, CL was linear with the concentration of quinalphos in the range of 0.02 mug/mL -1.0 mug/mL and the detection limit was 0.0055 mug/mL (3sigma). This method has been successfully applied to the detection of quinalphos in vegetable samples. According to the experimental data, the average recoveries for quinalphos in cherry tomato and green pepper 97.20% and 90.13%. Meanwhile, the possible mechanism was proposed.
|Haoyu Hu; Xiaoyu Liu; Feng Jiang; Xin Yao; Xiaocheng Cui|
Related Documents :
|20803366 - Headspace solid phase microextraction method for determination of triazine and organoph...
8664586 - Modification of aoac multiresidue method for determination of synthetic pyrethroid resi...
3624186 - Multiresidue method for determining substituted urea herbicides in foods by liquid chro...
16857206 - Determination of organochlorine and pyrethroid pesticides in fruit and vegetables using...
9772736 - Detection of thiazide-based diuretics in equine urine by liquid chromatography/mass spe...
20542476 - Determination and pharmacokinetics of gastrodin in human plasma by hplc coupled with ph...
|Type: Journal Article Date: 2010-06-24|
|Title: Chemistry Central journal Volume: 4 ISSN: 1752-153X ISO Abbreviation: Chem Cent J Publication Date: 2010|
|Created Date: 2010-07-12 Completed Date: 2011-07-14 Revised Date: 2011-11-21|
Medline Journal Info:
|Nlm Unique ID: 101314213 Medline TA: Chem Cent J Country: Unknown|
|Languages: eng Pagination: 13 Citation Subset: -|
|College of Food Science and Techonolgy, Huazhong Agricultural University, Wuhan 430070, China. firstname.lastname@example.org.|
|APA/MLA Format Download EndNote Download BibTex|
Journal ID (nlm-ta): Chem Cent J
Publisher: BioMed Central
Copyright ©2010 Hu et al
Received Day: 12 Month: 2 Year: 2010
Accepted Day: 24 Month: 6 Year: 2010
collection publication date: Year: 2010
Electronic publication date: Day: 24 Month: 6 Year: 2010
Volume: 4First Page: 13 Last Page: 13
Publisher Id: 1752-153X-4-13
PubMed Id: 20576096
|A novel chemiluminescence assay of organophosphorous pesticide quinalphos residue in vegetable with luminol detection|
|Haoyu Hu1||Email: email@example.com|
|Xiaoyu Liu1||Email: firstname.lastname@example.org|
|Feng Jiang1||Email: email@example.com|
|Xin Yao1||Email: firstname.lastname@example.org|
|Xiaocheng Cui1||Email: email@example.com|
1College of Food Science and Techonolgy, Huazhong Agricultural University, Wuhan 430070, China
Organophosphorus pesticides are widely used in agriculture due to their high insecticidal activity. They are toxic organic chemicals which can irreversibly inhibit acetylcholinesterase (AChE) which is essential for the function of the central nervous system [2,3]. As the pesticide residue is a potentially serious hazard to human health, the control and detection of pesticide residue plays a very important role in minimising risk. Many methods have been developed in the last few years for the detection of organophosphorus pesticides. The most widely used methods are gas chromatography (GC) [5-7], high-performance liquid chromatography (HPLC) [8,9], gas chromatography-mass spectrometry(GC-MS) , immune assay and fluorescence [11,12]. These methods are accurate and selective, but they require relatively expensive instrumentation and skilled technicians.
Chemiluminescence (CL) is defined as the production of electromagnetic radiation (ultraviolet, visible or infrared) observed when a chemical reaction yields an electronically excited intermediate or end product, which either luminesces or donates its energy to another molecule responsible for the emission. The CL phenomenon can be applied as detection technique for the monitoring of a wide variety of compounds in diverse fields, such as clinical, pharmaceutical, biomedical, environmental and food analysis [13-15]. Compared with those methods mentioned above, the chemiluminescence(CL) method has been growing in popularity and acceptance because of its advantages such as high sensitivity, rapid assay speed and simple instrumentation. CL method has been applied to the determination of organophosphorus pesticides residues during recent years[16-19].
Quinalphos (O,O-diethyl-O-quinoxalinyl phosphorothioate) is one of the most widely used organophosphorus insecticides in agriculture, and is applied to control of incidence of pests over crops such as cotton, tea, citrus and rice. At present, most of the analytical methods employed for the detection of quinalphos residues are based on chromatographic techniques , chromatographic techniques-mass spectrometry  and fluorescence. Until now, to our knowledge, there have been no reports of detecting quinalphos using a direct CL method. In our study, we found that the CL signal could be enhanced on the reaction of quinalphos with luminol-H2O2 in alkaline medium. Based on these findings, a sensitive, simple CL method for the detection of quinalphos was developed. The method has been applied to the detection of quinalphos in vegetable samples with satisfactory results. Further study was focused on the mechanism of quinalphos and the possible mechanism was proposed.
As the CL reagent, luminol concentration was an important factor which affected the CL intensity. The effect of luminol concentration on the CL intensity was examined in the range of 1.0 × 10-5 mol/L-1.0 × 10-3 mol/L, with 3 replicates. ΔI (the increasing amount of CL intensity) reached the maximum value when the concentration of luminol solution was 5.0 × 10-4mol/L. Therefore, for the experiments, the concentration of luminol was maintained at the optimal value of 5.0 × 10-4mol/L.
The effect of H2O2 concentration on the CL intensity was tested in the range of 0.05 mol/L-1 mol/L, with 3 replicates. The result (Figure 1) showed that ΔI reached the maximum value when the concentration of H2O2 was 0.05 mol/L. Therefore 0.05 mol/L was chosen as the optimal H2O2 concentration for further experiment.
The pH of the reaction of quinalphos with luminol-H2O2 in alkaline medium is an important parameter. The effects of a medium with pH in the range 12.5-13.5 were investigated, with 3 replicates. ΔI reached the maximum value when the pH was 13. Therefore pH 13 of luminol solution was selected as optimum for consequent research .
Our preliminary experiment showed that the CL reaction of luminol-H2O2- organophosphorus could be sensitized by several surfactants and inorganic salts. Surfactants can form micelles which can change the physical characteristics of molecular guests and their reactivity in aqueous solutions. Thus, two non-ionic surfactants (Tween-80, Polythylene Glucol-400(PEG-400)), two anionic surfactants (sodium dodecyl sulplhate (SDS), sodium dodecyl benzene sulplhate(SDBS)), one cationic surfactants (Cetyltrimethylammonium bromide (CTMAB)) and five inorganic salts (KBr, NaBr, NaCl, KI, KCl) were tested. However, the results (Table 1) showed that the effect of enhancers were not obvious under strong alkaline condition and the CL intensity was even inhibited by some surfactants. It indicated that quinalphos can apparently enhance the CL intensity of the luminol-H2O2 system without sensitizers.
The effect of some common inorganic ions and organic compounds on the CL reaction was tested by analyzing a standard solution of quinalphos (1.0 × 10-7 g/mL) to which increasing amounts of foreign ions were added. The tolerance limit was taken as the amount which caused a relative error of ± 5% in the peak height. Because some metal ions such as Cu (II), Co (II) may interfere the CL system in the luminol-hydrogen peroxide method. The tolerable ratio for foreign species was 1000-fold for glucose, CO32-, NO3-, Cl-, Na+; 100-fold for Mg2+; 1-fold for Pb2+; 0.01-fold for Co2+, Fe3+, Cu2+[23-26]. It can be seen that obvious interference was caused by Co2+, Fe3+ and Cu2+. Thus, 1.0 × 10-3 mol/L of EDTA was added to the luminol solution to restrain the interference from metal ions.
Under the optimal conditions, the calibration curve of ΔI against quinalphos concentration was linear in the range of 2 × 10-8g/mL-1 × 10-6g/mL and the calibration curves was y = 1081 × -2650.4 (where × is the concentration of quinalphos, 10-8g/mL), with the correlation coefficient of 0.9921. The detection limit of quinalphos was 0.0055 μg/mL, calculated from the International Union of Pure and Applied Chemistry (IUPAC) recommendations (3σ). The relative standard deviations (RSD) for 7 injections with 1 × 10-7g/mL quinalphos was 5.6%.
The proposed method was applied to the assay of quinalphos in vegetable sample. The eluent of quinalphos which was sprayed on the surface of vegetables was analyzed. According to the experimental data, the average recoveries for quinalphos in cherry tomato and green pepper 97.20% and 90.13% (Table 2). The relative standard deviations (RSD) for recoveries of quinalphos on the surface of cherry tomato and green pepper were 5.6% and 4.9%.
In this experiment, the kinetic characteristics of the proposed CL reaction were studied. The response curve of luminol (5 × 10−4 mol/L) CL reaction in the present quinalphos (1 × 10−7 g/mL) was recorded to study the kinetic characteristic of the CL reaction. Figure 2 demonstrated that the CL intensity peak appeared within 1 s of the injection of the quinalphos. The CL signals would decrease to a very low level within 20 s. The kinetic curve indicated the CL method was rapid and sensitive enough to be suitable for the detection of quinalphos.
Many research works have focused on the CL reaction mechanism of the luminol system. The research results have confirmed that the 3-aminophthalate anion was the emitter irrespective of medium and oxidant used. The maximum emission wavelength of luminol was about 420 nm. The resulting fluorescence spectrum (Figure 3) indicated that the maximum emssion wavelength of three systems (Luminol, Lumino-H2O2 and quinalphos-Lumino-H2O2) was also near 420 nm and the signal of fluorescence emission spectrum of quinalphos-lumino-H2O2 system is higher than lumino-H2O2 system. This means that the emitter of quinalphos-lumino-H2O2 system was also 3-aminophthalate anion.
Based on the analysis of the fluorescence spectrum combined with the kinetic curve, the possible mechanism of the present reaction was proposed as following:  Quinalphos was oxidized by H2O2 to peroxophosphonate;  Peroxophosphonate oxidized luminol to produce an excited state 3-aminophthalate anion;  The excited state 3-aminophthalate anion relaxed to the ground state, producing the observed emission [27,28] (Figure 4).
In this work, a direct CL method for determination of quinalphos is presented based on the reaction with luminol-H2O2 in an alkaline medium. CL reaction could occur with lower concentration of quinalphos without enhancers such as organized surfactant. The method was applied to the detection of quinalphos in vegetable samples. In the following, the mechanism was also investigated in detail through examination of the fluorescence spectrum and kinetic curve.
All reagents were analytical reagent grade and distilled water was used throughout these experiments. Luminol (5-amino-2,3-dihydro-1, 4-phthalazinedione, 99%) was purchased from the Corporation of Sigma(USA). Quinalphos standard solution (0.1 mg/mL in acetone) was purchased from the Corporation of Standard Material (Beijing, China). Tween-80(Amresco), PEG-400(Guangdong, China), SDS(Guangdong, China), SDBS(Shanghai, China), CTMAB(Wuhan, China), KBr(Guangdong, China), NaBr(Tianjin, China), NaCl(Jiaozuo, China), KI(Wuhan, China), KCl(Wuhan, China) were analytical reagent grade.
The 0.01 mol/L luminol stock solution was prepared by dissolving 0.1772 g luminol with 2 mL 1 mol/L NaOH solution and diluted with distilled water to 100 ml. The luminol solution was stable for at least 1 week when stored in refrigerator at 4°C. Working standard solutions of luminol were freshly prepared from the stock solution by appropriate dilutions before use and adjusted its pH with 0.1 mol/L NaOH. The 0.01 mg/mL quinalphos stock solution was prepared by diluting 0.1 mg/mL standard solution of quinalphos with 1 mL acetone and then diluting to 10 mL with distilled water. The obtained stock solution was stored in refrigerator at 4°C [29-31].
The CL signal was measured by a BPCL ultra-weak luminescence analyzer (Institute of Biophysics, Chinese Academy of Science, Beijing, China) as shown in Figure 5. The CL intensity, amplified by a sensitive photomultiplier tube (PMT) operated at -400 V, was measured with a detector under the control of a computer. The CL intensity ΔI was calculated by ΔI = Is −I0, where Is and I0 are the CL signals in presence and absence of quinalphos respectively. The determination method was based on the relationship between ΔI and corresponding concentration of quinalphos. The fluorescence spectrum was obtained by RF-5301PC fluorescence recording spectrophotometer (Shimadzu, Japan).
The proposed method was utilized for the determination of quinalphos in vegetable sample. Cherry tomato and green pepper were bought from the market in our campus. The weight of cherry tomato was about 15 g. The weight of green pepper was about 10 g. They were cleaned with distilled water. In order to perform the recovery test, a known amount of quinalphos standard solution was added to the sample and then washed with distilled water. The washings were diluted to suitable concentration with distilled water for analysis.
The authors declare that they have no competing interests.
All authors contributed to the experimental design. Xiaoyu Liu focused on the experiment design and contributed to drafting the manuscript. Haoyu Hu and Feng Jiang carried out nearly all of the laboratory work. Xin Yao and Xiaocheng Cui deal with the data analysis. All authors read and approved the final manuscript.
This study was supported by the Tackle Key Project Foundation of Hubei Province of China (Grant No.2006AA201C40).
|Li AF,Liu XY,Kong J,Hu HY,Sun LH,Qian Z,Determination of organophosphorous pesticide phosphamidon in environmental water with luminol chemiluminescence detectionJournal of AOAC InternationalYear: 200992391491819610385|
|Taira K,Aoyama Y,Kawamata M,Long QT and ST-T change associated with organophosphate exposure by aerial sprayEnviron Toxicol PharmacolYear: 200622404510.1016/j.etap.2005.11.008|
|Shigeaki I,Takeshi S,Hiroyasu M,Yosuke S,Kensuke T,Isotoshi Y,Sadaki I,Rapid simultaneous determination for organophosphorus pesticides in human serum by LC-MSJournal of Pharmaceutical and Biomedical AnalysisYear: 20074425826410.1016/j.jpba.2007.01.03617337150|
|Li BX,He YZ,Xu CL,Simultaneous determination of three organophosphorus pesticides residues in vegetables using continuous-flow chemiluminescence with artificial neural network calibrationTalantaYear: 20077222323010.1016/j.talanta.2006.10.02319071606|
|Ahmadi F,Assadi Y,Rezaee M,Determination of organophosphorus pesticides in water samples by single drop microextraction and gas chromatographyflame photometric detectorJ. Chromatogra.AYear: 200611011-230731210.1016/j.chroma.2005.11.017|
|Jin Y,Yao JB,Fu HB,Pan W,Geng QH,Ma W,Rapid determination of organophosphorus pesticide residues in vegetables and fruits by gas chromatographyChinese Journal of Health Laboratory TechnologyYear: 200717711531154|
|Li SX,Huang WX,Chen M,Detetmination of Chlorpyrifos in Water by Gas ChromatographyJ Environ HealthYear: 2006235458459|
|Benno A,Ruud C,Rob J,Hans G,Odile M,Determination of polar organophosphorus pesticides in aqueous samples by direct injection using liquid chromatography-tandem mass spectrometryJournal of Chromatography AYear: 2001918677810.1016/S0021-9673(01)00660-411403457|
|Martha P,María L,A validated matrix solid-phase dispersion method for the extraction of organophosphorus pesticides from bovine samplesFood ChemistryYear: 20091141510151610.1016/j.foodchem.2008.11.006|
|Lu JZ,Lau C,Lee MK,Ka M,Simple and convenient chemiluminescence method for the determination of melatoninAnalytical LettersYear: 2002455193198|
|Suvardhan K,Kumar K,Chiranjeevi P,Extractive Spectrofluorometric Determination of Quinalphos Using Fluorescein in Environmental SamplesEnvironmental Monitoring and AssessmentYear: 200510821722710.1007/s10661-005-4690-x16160788|
|Duran M,Muñoz de la Peña A,Acedo-Valenzuela MI,Jiménez Girón A,Stopped-flow and kinetic-fluorimetric determination of quinalphos in water samplesTalantaYear: 200669239740210.1016/j.talanta.2005.08.00618970580|
|José Antonio M,Aurelia Alañón M,Pablo Fernández L,Automatic chemiluminescence-based determination of carbaryl in various types of matricesTalantaYear: 200668358659310.1016/j.talanta.2005.04.05118970361|
|Lau C,Lu JZ,Kai M,Chemiluminescence determination of tetracycline based on radical production in a basic acetonitrile-hydrogen peroxide reactionAnal LettYear: 20045032235239|
|Li B,Zhang Z,Jin Y,Plant tissue-based chemiluminescence flow biosensor for glycolic acidAnal ChemYear: 20017361203120610.1021/ac000796k11305652|
|Gámiz-Gracia L,Garcia-Campaña AM,Soto-Chinchilla J,Huertas-Pérez JF,González-Casado A,Analysis of pesticides by chemiluminescence detection in the liquid phaseTrAC Trends in Analytical ChemistryYear: 20052492794210.1016/j.trac.2005.05.009|
|Liu XY,Li AF,Chen M,Wu MC,Study on Chemiluminescence Assay of Organophoaphorous Pesticides Phoxim in VegetableChinese Joumal of Analytical ChemistryYear: 2007351809181310.1002/cjoc.200790334|
|Xie FR,Tu MZ,Xie ZH,Determination of Trichlorfon by Flow Injection Analysis with Chemiluminescence DetectionChinese Journal of Spectroscopy LaboratoryYear: 2006233644647|
|Li AF,Liu XY,Kong J,Huang R,Wu MC,Chemiluminescence Determination of Organophosphorus Pesticides Chlorpyrifos in VegetableAnalytical LettersYear: 2008411375138610.1080/00032710802119228|
|Jia GF,Lv CG,Zhu WT,Qiu J,Wang XQ,Zhou ZQ,Applicability of cloud point extraction coupled with microwave-assisted back-extraction to the determination of organophosphorous pesticides in human urine by gas chromatography with flame photometry detectionJournal of Hazardous MaterialsYear: 200815930030510.1016/j.jhazmat.2008.02.08118468789|
|Gallardo E,Barroso M,Margalho C,Cruz A,Vieira DN,López-Rivadulla M,Determination of quinalphos in blood and urine by direct solid-phase microextraction combined with gas chromatography-mass spectrometryJournal of Chromatography BYear: 2006832116216810.1016/j.jchromb.2005.12.029|
|Wang JN,Zhang C,Wang HX,Yang FZ,Zhang XR,Development of a luminol-based chemiluminescence flow-injection method for the determination of dichlorvos pesticideTalantaYear: 20015461185119310.1016/S0039-9140(01)00388-518968339|
|Hu YG,Yang ZY,Flow Injection-chemiluminescence Method for the Determination of Trace Cu2+ in Environmental SamplesJournal of Analytical ScienceYear: 2004202148150|
|Denis B,Paolo P,Gabriella F,Carlo M,Effect of eluent composition and pH and chemiluminescent reagent pH on ion chromatographic selectivity and luminol-based chemiluminescence detection of Co2+, Mn2+ and Fe2+ at trace levelsTalantaYear: 200772124925510.1016/j.talanta.2006.10.02619071610|
|Li BX,Wang DM,Lv JG,Zhang ZJ,Flow-injection chemiluminescence simultaneous determination of cobalt(II) and copper(II) using partial least squares calibrationTalantaYear: 200669116016510.1016/j.talanta.2005.09.01718970548|
|Guo XM,Xu XD,Zhang J,A novel method for Co(II) and Cu(II) analysis by capillary electrophoresis with chemiluminescence detectionChin Chemical LettersYear: 20071891095109810.1016/j.cclet.2007.06.015|
|White EH,Bursey MM,Chemiluminescence of luminol and related hydrazedes: the light stepJ Am Chem SocYear: 19648694094210.1021/ja01059a050|
|Zhang Z,Lu J,Zhang X,Luminol chemiluminescence reation in analytical chemistryChin Chemical ReagentsYear: 198793149156|
|Jiang CQ,Luo L,Spectrofluorimetric determination of human serum albumin using a doxycycline-europium probeAnalytica Chimica ActaYear: 2004506217117510.1016/j.aca.2003.11.013|
|Liu X,Du J,Lu J,Determination of parathion residues in rice samples using a flow injection chemiluminescence methodLuminescenceYear: 20031824524810.1002/bio.72214587074|
|Rao Z,Wang J,Zhang X,Determination of methyl-parathion using luminol-based chemiluminescence flow injection methodChin J Anal ChemYear: 2001294373377|
Selection of enhancers
|Enhancers||Concentration||The CL intensity of quinalphos|
Analytical results of quinalphos in vegetable
|Sample||Content of quinalphos||quinalphos Added||Found||Recovery (%)||RSD
n = 7(%)
|Cherry tomato||None||1 × 10-7g||9.720 × 10-8g||97.20||5.6|
|green pepper||None||1 × 10-7g||9.013 × 10-8g||90.13||4.9|
Previous Document: Genomic subtypes of breast cancer identified by array comparative genomic hybridization display dist...
Next Document: The mitochondrial gene orfH79 plays a critical role in impairing both male gametophyte development a...