Resonance Rayleigh scattering method for determination of ethionusing silver nanoparticles as probe

Hooshang Parham n, Sedighe SaeedChemistry Department, Faculty of Sciences, Shahid Chamran University, 6135714168 Ahvaz, Iran

a r t i c l e i n f o

Article history:Received 19 June 2014Received in revised form31 July 2014Accepted 1 August 2014Available online 11 August 2014

Keywords:Resonance Rayleigh scatteringEthionSilver nanoparticles

a b s t r a c t

A simple, novel and sensitive method was developed to determine ethion insecticide in water samples.This method was based on the interaction of ethion with silver nanoparticles (AgNPs) and quenching ofthe resonance Rayleigh scattering (RRS) intensity. The change in RRS intensity (ΔIRRS) was linearlycorrelated to the concentration of ethion over the range of 10.0–900.0 mg L�1. Ethion can be measured ina short time (3 min) without any complicated or time-consuming sample pretreatment process.Parameters that affect the RRS intensities such as pH, concentration of AgNPs, standing time, electrolyteconcentration, and coexisting substances were systematically investigated and optimized. Interferencetests showed that the developed method has a very good selectivity and could be used conveniently fordetermination of ethion. The limit of detection (LOD) and limit of quantification (LOQ) were 3.7 and11.0 mg L�1, respectively. Relative standard deviations (RSD) for 15.0 and 60.0 mg L�1 of ethion were4.1 and 0.2, respectively. Possible mechanisms for the quenching of RRS of AgNPs were discussed and themethod was successfully applied for the analysis of spiked real water samples.

& 2014 Elsevier B.V. All rights reserved.

1. Introduction

Pesticides and insecticides are used to protect agricultural cropagainst damaging caused by insects. However, ecological compart-ments such as lakes and rivers may be contaminated by thesechemicals through rains and wind, affecting many other organismsfar from the first target. Organothiophosphates (OTPs) with athiophosphoryl (P¼S) functional group constitute a broad classof widely used organophosphates (OPs) insecticides. Organopho-sphates insecticides include very lethal nerve agents and chemicalwarfare agents, such as, VX, Soman, and Sarin. OTP compounds areused frequently in agricultural lands worldwide and has resultedhighly toxic residuals in crops, livestock, and poultry productswhich has further led to their migration into underground aquifers[1–3]. These compounds are highly toxic to human health and arepowerful inhibitors of acetylcholinesterase (AChE) enzyme, caus-ing accumulation of acetylcholine at nerve endings in the periph-eral or central nervous system [4].

Current detection methods for OPs and OTPs include chroma-tography [5–13], a variety of other analytical approaches includingenzymatic assays [14], potentiometry [15], UV–visible spectro-photometry [16], and ion mobility spectrometry [17]. From apractical agricultural viewpoint, many of the above-mentioned

approaches have limitations such as lack of instrument portability,limited selectivity, difficulties in real-time monitoring, operationalcomplexity, and in some cases low sensitivity. Therefore, for thesake of human health and environmental pollution control, it isvital to develop fast, sensitive, convenient and effective methodsfor the analysis of OP pesticides in environmental samples.

Resonance Rayleigh scattering (RRS) has drawn much moreattention in recent years and made important contributions inmany scientific areas. When a particle is exposed to an electro-magnetic radiation, the electrons in the particle oscillate at thesame frequency as the incident wave. Resonance Rayleigh scatter-ing takes place when the wavelength of Rayleigh scattering islocated at or close to the molecular absorption band. The proper-ties of scattered light depend on the size, composition, shape,homogeneity of the nanoparticles, and refractive index of themedium [18,19].

In recent years, Resonance Rayleigh scattering (RRS) or reso-nance light-scattering (RLS) technique has been widely applied tothe determination of different analytes [20–23]. This methodshowed its high potential for the determination of metal ions[24], non-metallic inorganic substances [25,26], surfactants [27],biomacromolecules [28], and pharmaceuticals [29]. The method ischaracterized by high sensitivity, convenience in performance andsimplicity in apparatus (usually common spectrofluorophotometer).

Both silver nanoparticles (AgNPs) and gold nanoparticles(AuNPs) possess novel physical and chemical properties and havereceived considerable interests in recent years for their unique

Contents lists available at ScienceDirect

journal homepage: www.elsevier.com/locate/talanta

Talanta

http://dx.doi.org/10.1016/j.talanta.2014.08.0070039-9140/& 2014 Elsevier B.V. All rights reserved.

n Corresponding author. Tel.: þ98 611 3360018; fax: þ98 611 3337009.E-mail address: hoparham@yahoo.com (H. Parham).

Talanta 131 (2015) 570–576

optical and electrical properties. These metal nanoparticles havebeen investigated extensively for sensing [30–32], exhibit theirsignals in the visible spectral region under appropriate conditionsand give corresponding localized surface plasmon resonance lightscattering (LSPR-LS) band of the NPs [33,34].

Some of these noble metal nanoparticles show special opticalproperties such as strong resonance light scattering in the ordersof magnitude higher than light emission from strongly fluorescentdye molecules [35]. Such a character makes them ideal opticalprobes for chemical, biological and clinical applications [36–38].Silver nanoparticles (AgNPs) exhibit certain advantages such ashigher extinction coefficients, sharper extinction bands and higherratio of scattering to extinction. More recently, AgNPs are rapidlygaining popularity as a consequence, and some research groupshave been developing several strategies for optical sensors andimaging techniques using AgNPs as building blocks and labelingprobes [39–41]. In comparison, AgNPs are superior to AuNPs of thesame size on the LSPR-LS for its high light scattering power [42].It has recently been reported that AgNPs is a promising alternativeto AuNPs in many applications in the fields of medicine, micro-biology, and analytical chemistry [34].

Herein, we present a novel highly sensitive RRS method for thedetection of ethion insecticide (Fig. 1) on the basis of the formationof ethion–AgNPs aggregates (Scheme 1) and quenching of the RRSintensity [43–45]. The detection sensitivity can be significantlyimproved to mg L�1 level by monitoring of signal quenching ofhigh sensitivity RRS by AgNPs.

2. Experimental

2.1. Materials and reagents

All chemicals used in the experiments were of analytical gradeor higher without further purification. Ethion was purchased fromSigma-Aldrich (America) and a working solution of 10.0 mg L�1

was prepared for use in the experiment. Sodium citrate and silvernitrate were purchased from Merck (Darmstadt, Germany). Buffersolutions were prepared by adjusting the pH of 0.1 mol L�1 citricacid and phosphoric acid solutions to 6 using NaOH solution(0.1 mol L�1). All solutions were prepared in high-purity water.

2.2. Apparatus

A Shimadzu RF-5301PC spectrofluorophotometer (Japan) wasused for recording and measuring the RRS spectra. A pH-meter(827 pH lab, Metrohm1, Herisau, Switzerland) was used for pHadjustment. Transmission electron microscopy (906E, LEO,Germany) and scanning electron microscopy (SEM) (XL-30 elec-tron microscope, Philips, Eindhoven, The Netherlands) were usedto study the morphology of AgNPs and ethion–AgNPs.

2.3. Preparation of AgNPs

AgNPs were synthesized by citrate reduction of AgNO3 [46].Silver nanoparticles stock solution (2.0�10�1 mg mL�1) was pre-pared by dissolving 0.0158 g of AgNO3 in 40 mL of ultrapure waterand slow addition of 2 mL sodium citrate (1%) to the AgNO3

solution by heating at 80 1C with stirring for 30 min. The color ofthis solution changed gradually from colorless to yellow and it wasfinally diluted to 50 mL. Above solution was stored at 4 1C.

2.4. Measurement of the RRS intensity of AgNPs–ethion system

Appropriate amounts of the AgNPs solution (2 mL of2.0�10�1 mg mL�1), 1 mL of citrate buffer (pH 6), 1.0 mL of the0.01 mol L�1 of KCl electrolyte, and certain volumes of ethionstandard solutions were added into a 10.0-mL flask. The resultingsolution was diluted to 10 mL and was vortex-shaken to mixthoroughly and kept for 3 min. The RRS spectra of the solutionswere recorded with synchronous scanning at λex¼λsc¼281 nm(i.e., Δλ¼0 nm), slit widths were kept at 1.5 nm, and RRS intensityof AgNP solutions in the absence (I0) and the presence of ethion(IRRS) was recorded. Fig. 2 shows the recorded RRS spectra of theblank solution and the test solution and the difference in RRSintensity values (ΔIRRS¼ I0–IRRS) in the wavelength range of200–800 nm. As it is seen in Fig. 2, two peaks are obtained atλex¼λsc¼281 and λsc¼2λex¼562 nm and 281 nm was selected asoptimum RRS wavelength for further works. Fig. 3 shows theabsorption spectrum (black, wavelength range 260–500 nm) andRRS spectrum (red, λex¼281 nm, scattering wavelength range260–500 nm) of AgNPs solution (blank). It must be mentionedthat AuNPs were also examined for detection of ethion and theresults were compared with those obtained by AgNPs. The resultsshowed that AuNPs can detect the target analyte (ethion), but theyshow longer response time (more than 7 min in comparison to3 min for AgNPs) and lower sensitivity (smaller ΔIRRS) with respectto AgNPs at the same conditions.

3. Results and discussion

3.1. Shape and size of AgNPs and AgNPs–ethion

The structural characteristics such as shape and size of AgNPsand AgNPs–ethion were investigated by TEM and SEM (Fig. 4).It can be seen from these TEM and SEM images that the averagediameters of the as synthesized AgNPs were about 20.0 nm andalso particles were comparatively homogenous, well dispersed,and almost spherically shaped without any obvious aggregation(Fig. 4A and C). It is well known that thiols will self-assemble intostrictly arranged monolayers (SAMs) onto the surface of themetals, especially gold, silver, and copper [47]. These SAMs havebeen intensely studied and are of great interest due to uniqueproperties of the resulting surfaces [47]. These properties includestabilization and passivation to other reactions. Silver metal hashigh affinity for reaction with thio groups and a new product isformed through the combination of ethion (containing 4 sulfuratoms). The shape of the new particles is different from that of theAgNPs and they are no longer spherically shaped, but aggregatedtogether and form an inhomogeneous cluster which is obviouslybigger than the original AgNPs (Fig. 4B and D). Overall, thecombination of ethion with the AgNPs not only increased the sizeof the nanoparticles, but also changed their apparent shape. TheAgNPs–ethion complex has a bigger size and contains an inhomo-geneous aggregate in which the spherical shaped AgNPs werewrapped around by ethion molecules and covered the activeoptical surface of silver nanoparticles and sedimentation of com-plex that led to the quenching of RRS intensity of silver nanopar-ticles. It must be mentioned that prepared AgNPs are stable for 2months (stored at refrigerator, 4 1C) and the recorded RRS inten-sity of nanoparticles was changed from 940 (first day) to 910 after50 days (changing about 3%).Fig. 1. Chemical structure of ethion insecticide.

H. Parham, S. Saeed / Talanta 131 (2015) 570–576 571

3.2. Spectral characteristics

As well known, RRS is a process produced by the resonance ofscattering and absorption of light when the wavelength of RRS islocated at or close to its molecular absorption band. In such a case,the frequency of the exciting electromagnetic wave is equal to thatof scattering light. In the present study, different wavelengthsfrom 260 to 320 nm were examined and RRS spectra of AgNPs,

AgNPs–ethion complex and ethion solutions were compared.AgNPs showed intense scattering of light in the wavelength regionof 270–300 nm and in presence of ethion insecticide, the RRSintensity is decreased significantly. The RRS spectra of AgNPs,AgNPs–ethion and ethion solutions were examined at excitationwavelengths of 260, 270, 280, 290, 300, 310 and 320 nm and themaximum ΔI is located at 281 nm for λex¼λsc¼281 nm. The RRSspectra of the AgNPs, AgNPs–ethion complex and ethion wereoverlaid (seven spectra for each solution) and the results showedthat (1) the RRS intensity of the ethion solution is very weak andnearly zero; (2) the AgNPs shows somewhat strong RRS intensity,and the maximum RRS wavelength is located at around 290 nm;(3) the RRS intensity of the AgNPs greatly decreases after theaddition of ethion, but the maximum difference between scatter-ing signals from AgNPs and AgNPs–ethion (ΔIRRS) occurs at281 nm. This observation led to the development of a sensitivemethodology using silver nanoparticles as optical sensor forethion determination.

3.3. Optimization of the experimental conditions

3.3.1. Effects of pH, type and volume of buffer solution on RRSintensities

It is well known that pH value can readily affect the reactionbetween AgNPs and ethion molecules and influence the RRS signalsof detection system. Therefore, the influence of pH on the RRSintensity of the system was studied over a pH range of 4–11, and theresults are shown in Fig. 5. The pH of the working solutions wasadjusted by dilute (0.01 mol L�1) HCl and NaOH solutions. As can beseen from the figure, the ΔIRRS of the system depends greatly on thepH value. It increased sharply when the pH increased from 4 to 6,whereas it decreased greatly with the continuous increase of pHabove 6. At low pHs, thio groups of ethion interact with H3Oþ ions(protonation of thio groups of ethion) which can compete withAgNPs and ΔIRRS decreases. However, at pH values higher than 6,hydroxide ions seems to compete with ethion in terms of adsorptiononto the surface of silver nanoparticles leading to inhibition ofinteraction between AgNPs and ethion which increases the IRRS andconsequently decreasing the ΔIRRS (ΔIRRS¼ I0–IRRS).

Two buffer solutions were examined and citrate (0.1 mol L�1)produced better results with respect to phosphate (0.1 mol L�1). Intoa 10 mL volumetric flask were added 2 mL of 2.0�10�1 μg mL�1 ofAgNPs solution, 1 mL of buffer (pH 6) and appropriate amounts ofethion solution, respectively. The solution was finally diluted to10 mL, mixed thoroughly and kept for 10 min.

The effect of citrate buffer volume was also studied and theresults showed that 1.0 mL can provide maximum ΔIRRS. Therefore,1.0 mL of the citrate buffer with pH 6 was selected as the optimumexperimental medium.

Scheme 1. Schematic of reaction of AgNPs with ethion insecticide which produces AgNP–ethion cluster at pH 6.

Fig. 2. RRS spectra of AgNPs in the absence (brown) and presence of ethion (green).(For interpretation of the references to color in this figure legend, the reader isreferred to the web version of this article.)

Fig. 3. (A) Absorption (black) and RRS (red) spectra of AgNPs solution. Conditions:[AgNPs]¼0.4 mg mL�1; λex¼281 nm; scattering spectrum was scanned in thewavelength range of 260–500 nm and maximum RRS occurred at λsc¼281 nm;slit of excitation, 1.5 nm; slit of emission, 1.5 nm. (For interpretation of thereferences to color in this figure legend, the reader is referred to the web versionof this article.)

H. Parham, S. Saeed / Talanta 131 (2015) 570–576572

3.3.2. Effect of AgNPs concentrationBy increasing the amount of AgNPs in the experimental solu-

tion, the intensity of RRS of this system increased. Due to thelimitations of spectrofluorophotometer which could not readintensities higher than 1000, a concentration of 0.08 mg mL�1 ofAgNPs in the final solution was used as optimum. Considering thehigh RRS intensity of the system regent blank, 0.08 mg mL�1

AgNPs, and low RRS intensity of AgNPs-ethion mixture, high ΔIRRSwas obtained and used for determination of trace concentrationsof ethion in water samples.

3.3.3. Effect of surfactantsThe effects of different surfactants on the system were studied.

The results showed that the presence of cationic surfactants, suchas cetyltrimethyl ammonium bromide (CTAB), can increase theRRS intensity of both AgNPs and AgNPs–ethion solutions. The RRSintensity of AgNPs–ethion solution (IRRS) increases more than theRRS intensity of AgNPs (I0) and so ΔIRRS decreases in presence ofsuch cationic surfactant. Sodium dodecyl sulfate (SDS) as ananionic surfactant was also tested on the system and RRS intensityof both solutions decreased dramatically. Based on the aboveresults, it could be seen that the biggest ΔIRRS and highersensitivity was obtained in the absence of common surfactants.

3.3.4. Effect of ionic strengthThe effect of ionic strength on RRS processes was examined

using different salts such as KCl, KNO3 and NaCl as electrolyte andKCl gave better results. Results show that ΔIRRS is increased byincreasing the salt concentration up to 0.001 mol L�1 of KCl. But, I0of the blank is decreased in more concentrated (up to0.01 mol L�1) solutions due to the aggregation of nanoparticlesand ΔIRRS decreases as a result. The decrease in RRS intensity ofAgNPs (I0) in the presence of KCl or NaCl should be related to thesurface-state of nanoparticles rather than the size of nanoparticleaggregates. The RRS intensity should be sensitively dependent onthe surface-state of nanoparticles as well as the aggregate size.Therefore, it is possible that KCl or NaCl could change the surface-state of AgNP in addition to driving the aggregation of AgNPs [48].

Fig. 4. TEM and SEM images of AgNPs before and after addition of ethion: (A) TEM of AgNPs, (B) TEM of AgNPs–ethion, (C) SEM of AgNPs and (D) SEM of AgNPs–ethion.

Fig. 5. Influence of pH on ΔIRRS of AgNPs in presence of 0.4 mg mL�1 of ethion; thepH of test solution was adjusted with dilute NaOH or HCl.

H. Parham, S. Saeed / Talanta 131 (2015) 570–576 573

Therefore, 1.0 mL of the 0.01 mol L�1 of KCl was used as theoptimum electrolyte amount in the test solution medium.

3.3.5. The order of addition and standing timeEffect of the adding order of different reagents was investi-

gated. The results indicated that the order of AgNPs–buffer–electrolyte–ethion is the best. Under the optimum condition, theeffect of time on the stability of RRS intensity was studied. Theresults showed that the ΔIRRS reached a maximum at 3 min afterall reagents were added, and it remained stable for over 2.0 h.Therefore, this system exhibits good stability.

3.3.6. Effect of interfering substancesUnder the optimal conditions, various coexisting substances

such as Mg2þ , Cl� , Naþ , Kþ , NH4þ , Ca2þ , Ac� , NO3

� , Fe3þ , SO42� ,

parathion, simazine and atrazine were examined for the inter-ference effect on determination of 0.5 mg mL�1 of ethion. Thepermitted relative deviation from the ΔIRRS value was 75%. Theresults indicated that most of the interfering substances testedcould be tolerated at relatively higher levels (100 mg mL�1). Para-thion can be tolerated up to 50 mg mL�1. Atrazine and simazine dointerfere at 5 mg mL�1.

3.3.7. Stern–Volmer constantThe experimental results of decreasing RRS intensity of AgNPs

by ethion insecticide showed a good fit to Stern–Volmer plots,giving linear relationship with quencher concentration. In orderto determine the quenching type mechanism, a study of the Ksv

(Stern–Volmer constant) from the modified Stern–Volmerequation (Eq. (1)) was carried out at different experimental tem-perature conditions submerging the systems in thermostatic bath.

Stern–Volmer equation for RRS intensity quenching is asfollows:

I0=I¼ 1þKsvCq ð1Þwhere I0 and I are intensities of the resonance Rayleigh scatteringof nanoparticles in the absence and presence of the quencherrespectively; Ksv is the Stern–Volmer constant; and Cq is theconcentration of the quencher.

The obtained Ksv values for each studied temperature are listedin Table 1. The linearity of the Stern–Volmer plot, as the value ofKsv which enhanced with increasing temperature (Fig. 6), indicatethat the quenching mechanism of AgNPs (decrease in I0) bypresence of ethion is a single dynamic quenching [48].

4. Analytical applications

4.1. Calibration graphs and detection limits

Under the optimal experimental conditions, calibration curvefor the determination of ethion by RRS was obtained. By increasingthe concentration of ethion to the test solution RRS intensity byAgNPs decreases and the results show a good linear relationship

over the range 10.0–900.0 mg L�1. The overlaid RRS spectra andcalibration graph are presented in Fig. 7. The linear regressionequation was ΔIRRS¼934.6 C (mg L�1)þ73.539 with regressioncoefficient r¼0.999. The limit of detection (LOD) and quantifica-tion (LOQ) were calculated in accordance to the official compendiamethods by k(Sb)/m, where k¼3 for LOD and k¼10 for LOQ, Sb isthe standard deviation from 9 replicate blank measurements(Sb¼1.16) and m (m¼937) is the slope of the calibration curve.The LOD and LOQ estimated were 3.7 and 11.0 mg L�1, respectively.

Intra- and inter-day precision and accuracy data (showingreproducibility and repeatability terms) for RRS detection ofethion in quality controlled (QC) water samples are summarizedin Table 2. The precision and accuracy of the present methodconform to the criteria for the analysis of water samples accordingto the guidance of US-FDA where the RSD determined at eachconcentration level is required not to exceed 15% (20% for LOQ)and R.E. within 715% (720% for LOQ) of the actual value [49].

The recovery values from QC water sample solutions containinglow, middle and high concentrations of ethion (50, 100 and600 mg L�1) were 98.072.3%, 10774.9% and 96.072.8%, respectively.

4.2. Determination of ethion in water samples

In order to test the validity of the method, the developedprocedure was applied for determination of ethion in water

Table 1Ksv valuesa for different experimentaltemperatures.

Temperature (K) Ksv value (L mg�1)

298 1.0102308 1.0573318 1.0795

a AgNPs were prepared and RRS intensity wasmeasured as described in general procedure;[ethion]: 0.0, 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 mg L�1.

Fig. 6. Influence of temperature on AgNPs RRS signals in presence of ethion.[ethion]: 0.0, 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 mg mL�1. Instrument conditions:λex¼λsc¼281 nm; slit of excitation, 1.5 nm; slit of emission, 1.5 nm.

Fig. 7. Overlaid RRS spectra of AgNPs–ethion (1–10) and calibration graph fordetermination of ethion. [ethion]: 0.0, 0.01, 0.05, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and0.8 mg mL�1. Instrument conditions: λex¼λsc¼281 nm; slit of excitation, 1.5 nm; slitof emission, 1.5 nm.

H. Parham, S. Saeed / Talanta 131 (2015) 570–576574

samples. Recovery tests were used to examine the reliability andaccuracy of the method, different amounts of ethion were spikedinto the dam (100 mL) and river (100 mL) water samples andethion content of each sample was determined at optimumconditions. The ethion content of different water samples andrecoveries of added analyte were evaluated and the resultsshowed that it is possible to determine the ethion concentrationin real sample solutions using the proposed method outlined inthis investigation (Table 3). Water samples were taken from theKaroon River and Dez dam. After standing for 24 h in refrigerator,the samples were filtered by a piece of filter paper. Knownamounts of ethion were added (20, 50 and 100 mg L�1) and weredetermined by the aforementioned procedure.

5. Conclusions

A novel and innovative methodology was developed for ultra-trace ethion quantification and successfully applied for its deter-mination in water solutions. The developed methodology in thisstudy is simple, fast, sensitive and cheap, especially when moresophisticated techniques such as chromatography are not avail-able. In this paper, a new resonance Rayleigh scattering methodwas used based on quenching of scattered light from the silvernanoparticles (AgNPs) after ethion addition. TEM and SEM imagesshowed the formation of huge clusters of AgNPs–ethion andsedimentation of complex. The quenching of AgNPs RRS anddecreasing the intensity of scattered light in the presence of traceamounts of ethion was studied and quenching mechanism wasproposed for RRS phenomenon. The proposed method is simple,

fast, sensitive and needs a simple spectrofluorophotometer. Themain advantage of the proposed method is the possibility of directethion determination with very good accuracy, sensitivity andtolerance. The method needs no time consuming pretreatmentprocesses such as solid phase extraction and micro-extractions forsamples used. The LDR, LOD and LOQ of the method are good andbetter than most of the reported methods except gas chromato-graphy and ion mobility spectrometry techniques (Table 4). Themethod needs no pretreatment processes like clean up of thesample and pre-concentration step which are mostly used inchromatographic procedures. The RSD of the method is betterthan all reported methods. The obtained results showed that theAgNPs can be applied as sensor for ethion determination in realwater samples.

Acknowledgment

The authors wish to thank Shahid Chamran University ResearchCouncil and Environment Protection Agency (EPA) of KhosestanProvince, Iran, for the financial support of this work (Grant 1392).

References

[1] H. Zhang, S. Wang, Z. Zhou, C. Pan, J. Zhang, W. Niu, Phosphorus Sulfur 183(2008) 280–290.

[2] J.H. Salas, M.M. Gonzalez, M. Noa, N.A. Perez, G. Diaz, R. Gutierrez, H. Zazueta,I. Osuna, J. Agric. Food Chem. 51 (2003) 4468–4471.

[3] R.J. Gilliom, Environ. Sci. Technol. 41 (2007) 3408–3414.[4] B.J. Walker, Organophosphorus Chemistry, London, Penguin Library of Physical

Sciences: Chemistry, 1972.[5] H. Liu, W. Kong, Y. Qi, B. Gong, Q. Miao, J. Wei, M. Yang, Chemosphere 95

(2014) 33–40.[6] J.P. dos Anjos, J.B. de Andrade, Microchem. J. 112 (2014) 119–126.[7] T.M. Gutiérrez Valencia, M.P. García de Llasera, J. Chromatogr. A 1218 (2011)

6869–6877.[8] G.F. Pang, Y.Z. Cao, J.J. Zhang, C.H.L. Fan, Y.M. Liu, X.M. Li, G.Q. Jia,

Z.Y. Li, Y.Q. Shi, Y.P. Wu, T.T. Guo, J. Chromatogr. A 1125 (2006) 1–30.[9] A. Garrido-Frenich, P. Plaza-Bolaños, J.L. Martínez-Vidal, J. Chromatogr. A 1153

(2007) 194–202.[10] H. Bagheri, Z. Ayazi, A. Es'haghi, A. Aghakhani, J. Chromatogr. A 1222 (2012)

13–21.[11] H. Bagheri, N. Alipour, Z. Ayazi, Anal. Chim. Acta 740 (2012) 43–49.[12] M. Schellin, B. Hauser, P. Popp, J. Chromatogr. A 1040 (2004) 251–258.[13] D.A. Lambropoulou, T.A. Albanis, J. Chromatogr. A 922 (2001) 243–255.[14] A.J. Russell, J.A. Berberich, G.E. Drevon, R.R. Koepsel, Annu. Rev. Biomed. Eng.

5 (2003) 1–27.[15] E. Khaled, M.S. Kamel, H.N.A. Hassan, H. Abdel-Gawad, H.Y. Aboul-Enein,

Talanta 119 (2014) 467–472.[16] C. De, T.A. Samuels, T.L. Haywood, G.A. Anderson, K. Campbell, K. Fletcher,

D.H. Murray, S.O. Obare, Tetrahedron Lett. 51 (2010) 1754–1757.[17] M.T. Jafari, Talanta 69 (2006) 1054–1058.

Table 2Precision and accuracy data for detection of ethion in water sample usingquenching of RRS of AgNPs (intra-day: n¼6; inter-day: n¼6 runs per day, 5 days).

Ethion conc. (mg L�1) RSD (%) Relative error (%)

Added Found (mean7S.D.) Intra-day Inter-day

50 4970.007 4.0 5.3 �2.0100 10370.011 3.3 4.1 þ3.0600 57670.043 2.7 3.7 �4.0

Table 3Analytical results of the determination of ethion content and recovery test of ethionin Dez dam and Karron river water samples with the proposed method (n¼6).[Conditions: 5 mL of water sample; 2 mL of 2.0�10�1 mg mL�1 AgNPs solution;1 mL of citrate buffer pH 6; standing time: 3 min; excitation wavelength: 281 nm;scattering wavelength: 281 nm; slit width: 1.5 nm].

Sample Ethion added(mg L�1)

Ethion found(mg L�1)

Recovery(%)

Dez dam watera – NDb –

25.0 23.170.003 92.850.0 53.170.009 106.2100.0 96.770.012 96.7

Karron river waterc 25.0 26.070.005 104.050.0 48.070.011 92.0100.0 101.370.016 101.3

a Dez dam water main components: Ca2þ¼52; Mg2þ¼29; Naþ¼37;CO3

2� ¼61; Cl�¼24; SO42� ¼25; NO3

� ¼9 mg mL�1; pH 7.3; EC¼853.b Not detected.c Karron River water main components: Ca2þ¼82; Mg2þ¼49; Naþ¼68;

CO32� ¼91; Cl�¼44; SO4

2� ¼35; NO3� ¼9 mg mL�1; pH 7.1; TDS¼387; EC¼1340.

Table 4The comparison of the proposed method (RRS) with some of other reportedmethods of ethion determination.

Method LDRa (mg L�1) LOD (mg L�1) RSD Ref.

GC–FPDb 40–1280 5–20 5.4 [5]SDME/GC–MSc 0.5–25 0.36 7.7–15.4 [6]MEPS–GC–MSd 0.5–500 0.05 7.6 [10]GC–MS 0.023–70 0.023 10 [12]Pot. Sensor 0–330 22 3.5–4.8 [13]UV–vis 400–4000 – – [14]IMSe 0.1–5.0 0.05 15 [17]RRS 10–900 3.7 0.2–4.0 Present work

a Linear dynamic range.b Gas chromatography with flame photometric detector.c Single-drop microextraction–gas chromatography coupled to mass spectro-

metry.d Microextraction in packed syringe–gas chromatography coupled to mass

spectrometry.e Ion mobility spectrometry.

H. Parham, S. Saeed / Talanta 131 (2015) 570–576 575

[18] J. Ling, C.Z. Huang, Y.F. Li, L. Zhang, L.Q. Chen, S.J. Zhen, Trends Anal. Chem. 28(2009) 447–453.

[19] A. Liang, Q. Liu, G. Wen, Z. Jiang, Trends Anal. Chem. 37 (2012) 32–47.[20] H.Y. Wang, Y.F. Li, C.Z. Huang, Talanta 72 (2007) 1698–1703.[21] H. Guo, K. Xue, L. Yan, Sens. Actuators B 171–172 (2012) 1038–1045.[22] J.X. Dong, W. Wen, N.B. Li, H.Q. Luo, Spectrochim. Acta A 86 (2012) 527–532.[23] R. Sun, Y. Wang, Y. Ni, S. Kokot, Talanta 125 (2014) 341–346.[24] M. Chen, H.H. Cai, F. Yang, D. Lin, P. Yang, J. Cai, Spectrochim. Acta A 118 (2014)

776–781.[25] G. Wen, D. Yang, Z. Jiang, Spectrochim. Acta A 117 (2014) 170–174.[26] Z. Jiang, L. Zhou, A. Liang, Chem. Commun. 47 (2011) 3162–3164.[27] L. Kong, Z.F. Liu, X.L. Hu, S.P. Liu, Sci. China Chem 53 (2010) 2363–2372.[28] S. Bi, Y. Wang, B. Pang, L. Yan, T. Wang, Spectrochim. Acta A 90 (2012) 158–164.[29] Y.Q. Wang, S.P. Liu, Z.F. Liu, J.D. Yang, X.L. Hu, Spectrochim. Acta A 105 (2013)

612–617.[30] W.J. Qi, D. Wu, J. Ling, C.Z. Huang, Chem. Commun. 46 (2010) 4893–4895.[31] J. Ling, Y.F. Li, C.Z. Huang, Anal. Chem. 81 (2009) 1707–1714.[32] M. Fan, M. Thompson, M.L. Andrade, A.G. Brolo, Anal. Chem. 82 (2010)

6350–6352.[33] H. Wang, D. Chen, Y. Wei, L. Yu, P. Zhang, J. Zhao, Spectrochim. Acta A 79 (2011)

2012–2016.[34] S.L. Smitha, K.M. Nissamudeen, D. Philip, K.G. Gopchandran, Spectrochim. Acta

A 71 (2008) 186–190.

[35] X. Liu, Q. Dai, L. Austin, J. Coutts, G. Knowles, J. Zou, H. Chen, Q. Huo, J. Am.Chem. Soc. 130 (2008) 2780–2782.

[36] B. Kong, A.W. Zhu, Y.P. Luo, Y. Tian, Y.Y. Yu, G.Y. Shi, Angew. Chem. Int. Ed. 50(2011) 1837–1840.

[37] X. Huang, I.H. El-sayed, W. Qian, M.A. El-sayed, J. Am. Chem. Soc. 128 (2006)2115–2120.

[38] Y. Jiang, H. Zhao, N. Zhu, Y. Lin, P. Yu, L. Mao, Angew. Chem. Int. Ed. 47 (2008)8601–8604.

[39] X. Han, H. Wang, X. Ou, X. Zhang, J. Mater. Chem. 22 (2012) 14127–14132.[40] M. Larguinho, P.V. Baptista, J. Proteomics 75 (2012) 2811–2823.[41] T. Lan, C. Dong, X. Huang, J. Ren, Talanta 116 (2013) 501–507.[42] J. Yguerabide, E.E. Yguerabide, Anal. Biochem. 262 (1998) 157–176.[43] L. Ying, Y. Guangwei, M. Chen, G. Meiying, Y. Chunxin, J. Nianqin, Anal. Lett. 44

(4) (2011) 709–716.[44] Z. Chen, G. Zhang, X. Chen, J. Chen, S. Qian, Q. Li, Analyst 137 (2012) 722–728.[45] C.C. Wang, M.O. Luconi, A.N. Masib, L.P. Fernández, Talanta 77 (2009)

1238–1243.[46] J. Zheng, X. Wu, M. Wang, D. Ran, W. Xu, J. Yang, Talanta 74 (2008) 526–532.[47] M.M. Sung, K. Sung, C.G. Kim, S.S. Lee, Y. Kim, J. Phys. Chem. B 104 (2000)

2273–2277.[48] J.H. Kim, J.S. Park, M.G. Kim, Chem. Phys. Lett. 600 (2014) 15–20.[49] J.C. Miller, J.N. Miller, Statistics for Analytical Chemistry, third ed., Ellis

Harwood, New York, 1984 (hide affiliations).

H. Parham, S. Saeed / Talanta 131 (2015) 570–576576