development of dispersive liquid–liquid microextraction method for the analysis of...

Download Development of dispersive liquid–liquid microextraction method for the analysis of organophosphorus pesticides in tea

Post on 26-Jun-2016

220 views

Category:

Documents

4 download

Embed Size (px)

TRANSCRIPT

  • Journal of Hazardous Materials 169 (2009) 907911

    Contents lists available at ScienceDirect

    Journal of Hazardous Materials

    journa l homepage: www.e lsev ier .com

    Develo exthe ana te

    Soleymaa Department o , Tehrab Electroanalyt

    a r t i c l

    Article history:Received 2 FebReceived in reAccepted 8 ApAvailable onlin

    Keywords:OrganophosphGC-FPDTea sample anDispersive liqu

    deterliquxturempleter; trform3 andetwe

    g/kg fosedlow c

    1. Introduction

    Pesticides including organochlorine pesticides (OCPs), organo-phosphorusare types opesticides pbut by bioaally becomeof their highhealth, OCPdeveloped cin many coronment mmost toxic pwater, fruitconsumed ttherapeuticals used forpesticides uble risks toin the worlimportant s

    Corresponistry, Iran Univfax: +98 21 77

    E-mail add

    countries have set their own maximum residue limits (MRLs) ofpesticides for tea and other plants consumed as infusions. Thus,for example, the European Community legislation established the

    0304-3894/$ doi:10.1016/j.jpesticides (OPPs), and nitrogen-containing herbicidesf well-known environmental contaminants. The use ofrovides benets for increasing agricultural production,ccumulation through the food web they can eventu-a risk or threat to both animals and humans. Becausely persistent properties and potential threat to human

    s have been prohibited to be produced and used in mostountries. Instead OPPs are used as a substitute for OCPsuntries nowadays because they can degrade the envi-ore easily [1]. Although OPPs as a whole are not theollutants, they can be traced in a wide range of surface

    , vegetable and foodstuff [2]. Many types of plants arehroughout the world as infusions for both pleasure andpurposes. Like other agricultural products, the materi-infusions must be subjected to control because of thesed for their cultivation, in order to minimise possi-human health. Tea is one of the most popular drinksd, so that such water-based drinks could represent anhare of total human exposure to pesticides [3]. Several

    ding author at: Department of Analytical Chemistry, Faculty of Chem-ersity of Science and Technology, Tehran, Iran. Tel.: +98 21 73912750;491204.ress: drmilani@iust.ac.ir (M.-R.M. Hosseini).

    MRLs for the pesticides considered in the present study at between0.02g/g for tetradifon and 5g/g for deltamethrin [4] in a widevariety of vegetables, although no MRL is specied in the case ofothers such as coumaphos. Different analytical procedures wereused for the determination of pesticides in medicinal plants andtea [3,511]. Owing to low concentration, the compounds of inter-est have to be separated from the matrix and concentrated to reachthe minimum level required for the particular detector used. Solid-phase extraction (SPE) [12], liquidliquid extraction (LLE) [13], stirbar sorptive extraction (SBSE) [14] and solid-phasemicroextraction(SPME) [11,15] have been used for the separation and preconcentra-tionofpesticides fromthe infusionmatrices.Actually, thereareonlyfew studies based on modern sample preparation methods such asSPME, SBSE (stirring bar sorptive extraction) and SFE (supercriticaluid extraction) focusing on the determination of pesticides in phy-tomedicines (herbal drugs, infusions, tinctures, dried extracts, etc.)[8,9,11,1416]. Plant infusions are complex samples, containing sev-eral endogenous compounds extracted from the leaves by the hotwater during their preparation. Also, it is possible to nd a widerange of different pesticide residues on these infusions, depend-ing on the precedence of a particular sample; when present, theseanalytes are usually found on extremely low levels (g/L or less).

    Therefore, the procedures for the chromatographic detectionand quantitation of organochlorine (OCP) and organophosphorus(OPP) on Passiora infusionsmust incorporate selective, robust and

    see front matter 2009 Elsevier B.V. All rights reserved.hazmat.2009.04.030pment of dispersive liquidliquid microlysis of organophosphorus pesticides in

    n Moinfara, Mohammad-Reza Milani Hosseinia,b,

    f Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technologyical Chemistry Research Center, Iran University of Science and Technology, Tehran, Iran

    e i n f o

    ruary 2009vised form 8 April 2009ril 2009e 16 April 2009

    orus pesticides

    alysisidliquid microextraction

    a b s t r a c t

    In this article, a new method for thedeveloped by using dispersive liquidphotometric detection (GC-FPD). Amifor the extraction of OPPs from tea sasolvents was rapidly dispersed in wausing DLLME. Recovery tests were peanalyte was in the range between 83.as relative standard deviation, varied bwas found ranging from 0.030 to 1sample preparation method, the propand has high-enrichment factors and/ locate / jhazmat

    traction method fora

    n, Iran

    mination of organophosphorus pesticides (OPPs) in tea wasid microextraction (DLLME) and gas chromatographyameof acetonitrile andn-hexanewas used as an extraction solvents. When the extraction process was nished, the mixture ofarget analyte was extracted to a small volume of n-hexane,ed for concentration 5.0g/kg. The recovery for each target117.4%. The repeatability of the proposed method, expresseden 3 and 7.8% (n=3). The detection limit of the method for teaor all the target pesticides. Compared with the conventionalmethod has the advantage of being quick and easy to operate,onsumption of organic solvent.

    2009 Elsevier B.V. All rights reserved.

  • 908 S. Moinfar, M.-R.M. Hosseini / Journal of Hazardous Materials 169 (2009) 907911

    effective clean-up and extraction steps [17]. Gas chromatography(GC) is a suitable technique for such a purpose [1115] but, dueto low concentration, the compounds of interest have to be sepa-rated from thematrix and concentrated to reach theminimum levelrequired foa new micrpersive liquDLLME are srecovery anthe determiOPPs [19], ctrihalomethphenyltin [2nortriptylin[29], three pphorus and[34] andhalhas been ucides [36] in

    Becauseapplied inwe selectedorganophoslished papeOPPs in teaDLLME suitGC-FPD. Thyield of themized.

    In this stnation of OPand n-hexaThis changeextraction a

    2. Experim

    2.1. Reagen

    All OPPsithion, malapurchasedfrom Mercktimes and was a solventMerck. Alsostandard) wused for thewas dissolva concentradard solutio4 C. The tea

    2.2. Instrum

    A gas chinjector systhe separa(99.9999%,sieve trap aUSA) was u35 cm/s. Thless modewas used iseparationcolumn wit

    dimethyl polysiloxane (Phenomenex, USA). The oven temperaturewas programmed as follows: initial 100 C, from100 C (held 2min)to 150 C at the rate of 25 C/min, from 150 to 175 C at the rateof 5 C/min, from 175 to 195 C at the rate of 2 C/min, from 195

    C aC runC, h-220air

    c cuginraturntroL scrwerK) fotion

    mple

    his stas stem

    g off aceh ratpm)ents,r it oof th(ga

    cap g-distloudyt tubfact,tion2 (DmaOPP

    ltratratep oft ond on(380

    ts ofuse thconichexaing tare

    onsur ceide dat coeadvC. Thtubeyringrecoof ag/Ln levtes wr the particular detector used. In the previous research,oextraction technique was demonstrated named dis-idliquid microextraction (DLLME). The advantages ofimplicity of operation, rapidity, low time and cost, highd enrichment factor [18]. Thismethod has been used fornation of polycyclic aromatic hydrocarbons (PAHs) [18],hlorobenzenes [20], chlorophenols [21], phenols [22],anes [23], polychlorinated biphenyls [24], butyl and5] ionizable organic compounds [26], amitriptyline ande [27], polybrominated diphenyl ethers [28], anilineshthalate esters [30], phthalate esters [31], organophos-plastizicers [32], triazine herbicides [33], antioxidantsogenatedorganic compounds [35] in liquid samples andsed for the determination of organophosphorus pesti-

    watermelon and cucumber samples.organophosphorus pesticides are the most widelymainland Iran to control agricultural crops insects,10 types of OPPs as the representative species of

    phorus pesticides. However, to date, none of the pub-rs have reported the use of DLLME for the analysis ofsample by GC-FPD. The aim of this study is to assess

    ability for the determination of OPPs in tea sample bye effects of different experimental parameters on thesample preparation step were also studied and opti-

    udy, we have developed a new method for the determi-Ps in tea after extraction with a mixture of acetonitrilene concentration with the developed DLLME method.in DLLME method was done to use any solvents in

    nd decrease detection limit.

    ental

    ts and standards

    (phorate, diazinon, disolfotane,methyl parathion, sum-thion, fenthion, profenphose, ethion, phosalone) were

    from polyscience (Niles, USA). n-Hexane was obtained(Germany). This solvent was distillated at least twoas used as an extraction solvent. Acetone, acetonitrile(suprasolv or gas chromatography) were obtained fromsodium chloride and triphenylphosphate (as internalere purchased from Merck. Doubly-distilled water waspreparation of aqueous solution. Each OPP (0.01000g)

    ed in 10.0mL acetone to obtain a standard solution withtion of 1000mg/L. A tea from 20.0mg/L of OPPs stan-n was prepared in acetone every week and stored atsample was obtained from local supermarkets.

    entation

    romatograph (Shimadzu GC 2010) with a split/splitlesstem, and a ame photometric detector was used fortion and determination of OPPs. Ultra pure heliumAir Products, UK), which passes through a molecularnd oxygen trap, (Chromatography Research Supplies,sed as the carrier gas at constant linear velocity of

    e injection port was held at 250 C and used in the split-with splitless time 0.5min. A deactivated glass linern order to decrease the degradation of products. Thewas carried out on a BP-5, 28.5m0.22mm cap

Recommended

View more >