Food Chemistry 210 (2016) 78–84

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Food Chemistry

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Analytical Methods

Development of dummy molecularly imprinted based on functionalizedsilica nanoparticles for determination of acrylamide in processed food bymatrix solid phase dispersion

http://dx.doi.org/10.1016/j.foodchem.2016.04.0800308-8146/� 2016 Elsevier Ltd. All rights reserved.

⇑ Corresponding author.E-mail addresses: m_ghaedi@mail.yu.ac.ir, m_ghaedi@yahoo.com (M. Ghaedi).

Maryam Arabi a, Mehrorang Ghaedi a,⇑, Abbas Ostovan b

aChemistry Department, Yasouj University, Yasouj 75914-35, IranbDepartment of Chemistry, Kerman Branch, Islamic Azad University, Kerman, Iran

a r t i c l e i n f o

Article history:Received 7 December 2015Received in revised form 11 April 2016Accepted 17 April 2016Available online 19 April 2016

Keywords:Molecularly imprintedDummy templateSilica nanoparticlesMatrix solid phase dispersionAcrylamide

a b s t r a c t

A novel technique was applied for the synthesis of dummy molecularly imprinted silica nanoparticles(DMISNPs). DMISNPs were characterized by Fourier transmission infrared spectrometry, scanning elec-tron microscopy and transmission electron microscope. The material was used as dispersant for the anal-ysis of biscuit and bread samples using matrix solid phase dispersion (MSPD). Of advantages of suchapproach may be counted as the simplicity of synthesis procedure, low consumption of organic solvent,mild working temperature during the synthesis, high binding capacity and affinity. The effect of variousparameters such as sample-to-dispersant ratio and eluents volume on extraction recovery was investi-gated and optimized by central composite design under response surface methodology. It was proventhat the proposed dispersant leads to high affinity toward acrylamide even in complicated matrices.Quantification of the acrylamide was carried out by high performance liquid chromatography with UVdetection (HPLC-UV).

� 2016 Elsevier Ltd. All rights reserved.

1. Introduction

Acrylamide (2-propenamide; Fig. 1Sa) as a low molecularweight hydrophilic compound exists in raw and boiled food(Wang, Lee, Shuang, & Choi, 2008). In 2002, the Swedish Nationaladministration and university of Stockholm reported that heat-treated potatoes and baked food contain high amount of acry-lamide (SNFA, 2002). Acrylamide has been classified as ‘‘probablycarcinogenic to humans” (Group 2A) by the International Agencyfor Research on Cancer (IARC, 1994). Therefore, it is of high interestto determine the acrylamide in the foodstuffs in particular incarbohydrate-rich food such as French fries, as well as foods pro-cessed and cooked at high temperatures under low moisture con-ditions (Wang et al., 2008). The acrylamide is formed duringcooking, frying and baking of fatty, carbohydrate- andasparagines-rich foods at temperatures exceeding 120 �C due tothe asparagines-glucose reaction (Millard reaction) or the decom-position of triglycerides (Paleologos & Kontominas, 2005). Numer-ous techniques such as solid phase extraction (Bortolomeazzi,Munari, Anese, & Verardo, 2012), matrix solid phase dispersion(Fernandes & Soares, 2007), ultrasonic-assisted (Shi, Zhang, &

Zhao, 2009) and solid phase micro extraction (Lee, Chang, & Dou,2007) were developed for the determination of acrylamide in dif-ferent samples (Bortolomeazzi et al., 2012; Fernandes & Soares,2007; Lee et al., 2007; Shi et al., 2009).

Molecularly imprinted polymers (MIPs) are man-made porousmaterials with highly selective binding cavities for recognizing asingle molecule or a family of related molecules (Ji et al., 2014)are used as suitable sorbent in several analytical techniques suchas liquid chromatography, capillary electrophoresis and capillaryelectro-chromatography, solid-phase extraction and ‘immunoas-say’ (Chen, Wang, & Shi, 2011; Nestic, Babic, Pavlovic, & Sutlovic,2013; Xu, Qiao, Ma, Zhang, & Xu, 2012). MIPs have many advan-tages including mechanical and chemical robustness, high selectiv-ity for target molecule and low preparation cost. MIPs which areapplied in solid phase extraction (Su et al., 2015), solid phase microextraction (Djozan & Ebrahimi, 2008) and stir bar (Zhua, Cai, Yang,Su, & Gao, 2006), are generally prepared via the co-polymerizationof the imprint-monomer complex and cross-linking monomers fol-lowed by the removal of the template molecules by solvent extrac-tion and chemical cleavage (Yu et al., 2015). The leakage of residualtemplate molecules after solvent extraction during the preparationof MIPs is a disadvantage for the MIPs, which may lead to uncer-tainties in the analyte quantification. This can simply be overcomeby using dummy template (DT) for the MIPs synthesis. Template

M. Arabi et al. / Food Chemistry 210 (2016) 78–84 79

bleeding in very expensive original templates achieved by themanipulation of the compound or polymerization of the template(thermal or UV irradiation) could result in unwanted compounddegradation (Feás et al., 2009). As a pre-condition, the dummymolecule must resemble the target analyte in terms of shape, sizeand functionalities without interference in analytical determina-tion (Du et al., 2013).

Recently, molecular imprinting technique impregnation on thesurface of nanoparticles (Yuan et al., 2012) has failure anddrawbacks is too deep embedded template that cause incompletetemplate removal, small binding capacity and low affinity masstransfer difficultly (Alexiadou, Maragou, Thomaidis, Theodoridis,& Koupparis, 2008). Nanostructured imprinted materials havelow dimensions and extremely high surface-to-volume ratio.Therefore, they provide complete removal of templates, better siteaccessibility, lower mass-transfer resistance and well definedmaterial shape (Zhai et al., 2009). The sol-gel route adequatelyobtains inorganic-based imprinted materials. The inorganic matrixemerges from sequential hydrolysis and condensation of metalalkoxides in acidic or basic aqueous media. Compared to sol-gelprocess, organic polymer-based molecular imprinting requireslarge volume of organic solvent, which is a disadvantage, whilesol–gel-based procedures results in more porosity, rigidity andchemical inertness (Wei, Tsai, Wu, & Chen, 2006). Varieties of func-tional groups such as amine (Atakay, Çelikbıçak, & Salih, 2012),thiol (Tao, Wang, Ma, Wu, & Meng, 2012) and phenyl (Burleigh,Markowitz, Spector, & Gaber, 2001) were used for the modificationof silica to increase interaction between analytes and the modifiedsilica as sorbents.

Matrix solid-phase dispersion (MSPD) as extraction and cleanup technique is based on dispersion of sample in relatively low sor-bent volume (Fernandes & Soares, 2007). Conventional applied dis-persion sorbents are molecularly imprinted polymer (Gañán et al.,2014), C18 (Fernandes & Soares, 2007) and florisil (Chen, Tsai, &Ding, 2014). The MSPD-based procedures greatly reduce the anal-ysis time, increase sample throughput, shorten turn-around timeand reduce solvent consumption as well as they are useful for dif-ferent types of samples such as solid, semi-solid and viscous sam-ples (Barker, 2000).

Experimental designs are effective tools for the simultaneousoptimization of variables and evaluation of statistical significanceof the factors involved. In comparison to one-variable-at-a-timeprotocol, the experimental design reduces the experimental runs,the time of analysis, the economic and environmental cost anderror. Recently, scientists employed these chemometrics tools forexperimental optimization (Roosta, Ghaedi, & Daneshfar, 2014).Central composite design (CCD) under response surface methodol-ogy (RSM) is a useful protocol for the simultaneous optimization ofvariables that permits concurrent optimization of multipleresponses (Ghaedi, Shahamiri, Mirtamizdoust, Hajati, &Taghizadeh, 2015). Additionally, the optimum conditions couldbe efficiently and accurately obtained with the minimum numberof experimental runs. Therefore, it was applied in this work.

Common protocol for the synthesis of molecular imprintinglayer coated on silica nanoparticles includes several steps andrequires high volume of organic solvent. This work is devoted tothe development of new strategy for the sol-gel synthesis of selec-tive sorbent based on dummy molecularly imprinted silicananoparticles in one step using 3-aminopropyltrimethoxysilane(APTMS) as functional monomer, propanamide (Fig. 1Sb) asdummy template and tetraethyl orthosilicate (TEOS) as cross lin-ker. The sorbent was used as dispersant in MISPD Clean-up tech-nique followed by High Performance Liquid Chromatography(HPLC) coupled to UV detection for the determination of acry-lamide from processed foods. The method was effective, facile,cheap and easy to use. Furthermore, very small amount of organic

solvent was required during the synthesis and MISPD process. Tothe best of our knowledge, no study using the DMISNPs as disper-sant sorbent in the MISPD method has been reported to extractacrylamide from food samples. Table 1S and Fig. 2S show the briefcomparison of different methods using molecular imprinting sor-bents (Peng et al., 2010; Song, Li, Wang, & Chen, 2009).

2. Materials and methods

2.1. Materials

APTMS and TEOS were purchased from Sigma-Aldrich (SaoPaulo, SP, Brazil). Acrylamide and propanamide (99% purity) werepurchased from Aldrich (Steinheim, Germany). Ultrapure waterwas obtained fromMilliQ gradient ultrapure water system. Metha-nol, ethanol and acetonitrile (HPLC gradient grade) were producedby J.T. Baker (Deventer, Holland). 3 mL empty solid phase extrac-tion (SPE) cartridges and polyethylene frits were purchased fromSymta (Madrid, Spain). Sea sand was supplied by Quality Chemi-cals S.L. (Esparraguera, Spain). All chemicals including ammoniumhydroxide and acetic acid were purchased from Merck (Darmstadt,Germany) with the highest purity available. Solutions were filteredprior to use through 0.45 lm pore size disposable nylon filters pur-chased from Análisis Vínicos (Tomelloso, Spain).

2.2. Instruments

High-performance liquid chromatography was performed on anAgilent 1100 liquid chromatography (Wilmington, DE, USA)equipped with a Micro Vacuum Degasser (model G1379A), a Qua-ternary Pump (model G1311A), a Series Multiple WavelengthDetector (model G13658 set at 210 nm for acrylamide), a sampleinjection valve with a 20 lL sample loop, and a Knauer C18 column(4.6 mm i.d. 250 mm, 5 lm). Data were collected and analyzedusing the Agilent Chemstation software. The mobile phase waswater – methanol (95/5, v/v) and the flow rate was 0.8 mL min�1.The mobile phase was filtered through a 0.45 lm filter anddegassed under vacuum before use. The system was operated atambient temperature.

The shape and surface morphology of the polymer were inves-tigated by field emission scanning electron microscope (FE-SEM,Hitachi S4160, Japan) under an acceleration voltage of 15 kV. Four-ier transform infrared (FT-IR) spectra were recorded using KBrdisks (FTIR-8300, Shimadzu). Absorption measurements were car-ried out on a Jusco UV–vis spectrophotometer model V-530 (Jasco,Japan) using a quartz cell with an optical path of 1 cm, at wave-length of 210 nm. An ultrasonic bath with heating system(Tecno-GAZ SPA, Ultra Sonic System, Italy) was used for theultrasound-assisted steps at frequency of 40 kHz and power of130W.

2.3. Samples

All samples (biscuits and breads) were purchased from a localsuper-market. 10 g of each sample was taken and grinded in anelectric grinder (Moulinex, Ecully, France) and stored at 4 �C untiluse for the analysis.

2.4. Preparation of imprinted and non-imprinted silica nanoparticles

The DMISNPs for the recognition of acrylamide sites were syn-thesized by the hydrolysis of TEOS using aqueous ammonia(Stöber, Fink, & Bohn, 1968). 1.2 mL of APTMS and 6 mL TEOS con-taining 1 mmol propanamide were added to the mixture of 100 mLof ethanol, 4 mL of deionized water and 3.2 mL of aqueous solution

80 M. Arabi et al. / Food Chemistry 210 (2016) 78–84

of 25% (w/w) ammonium as a catalyst under vigorous stirring at30 �C for 24 h. Subsequently, the processed silica particles werepurified by several cycles of centrifugation, decantation and re-suspension in methanol/acetic acid (90/10 v/v) by sonication untilthe dummy template was not detected by UV–Vis Spectropho-tometer. Finally, the as-prepared silica nanoparticles were driedat room temperature under vacuum for further use and appliedfor the same reaction in the absence of template.

2.5. DMISNPs-MSPD procedure

0.1 g of sample and 0.15 g of DMISNPs were mixed thoroughlywith 0.126 g of clean sea sand in small glass mortar and blendedtogether until homogeneous mixture was obtained. After the MSPDblending process, the mixture was packed into a polypropylene SPEcartridge with plugged, while putting the porous PTFE disks at bothends leads to retain the entire mixture. The cartridge was rinsedwith 1 mL of hexane and acrylamide was eluted from the cartridgeusing 2.5 mL of ACN/methanol (50/50 v:v) at a constant flow rate of1.5 mL min�1. To achieve dryness, the eluent was evaporatedunder vacuum at room temperature and the residue was reconsti-tuted with 500 lL of mobile phase and filtered through nylon fil-ters (0.45 lm) prior to the HPLC-UV analysis.

Fig. 1. (a) Scanning electron micrographs (SEM) of DMIPSNPs (b) TEM image ofDMISNPs.

3. Results and discussion

3.1. Preparation and characterization of DMISNPs and NISNPs

Biscuit and bread consist of high amount of proteins and lipids,which are strongly adsorbed to the surfaces of hydrophobic MIPs,negatively interfering with their recognition properties (Bures,Huang, Oral, & Peppas, 2001). Therefore, for avoiding such interfer-ence, hydrophilic DMISNPs and NISNPs were prepared via sol-gelprocess in aqueous ammonia solution. Additionally, compared toacrylic-based MIP, inorganic imprinted nanoparticles extremelylower the consumption of toxic organic solvent during the synthe-sis procedure over mild temperature. On the other hand, as men-tioned before, the leakage of residual template molecules aftersolvent extraction, which leads to error in results, can be simplyovercome using propanamide as dummy template. As shown inFig. 1S, propanamide resembles acrylamide in terms of shape, sizeand functionalities except the replacement of C@C with CAC.When mixed with the DMISNPs, acrylamide molecules can easilyenter the imprinted cavities and bind hydrogen bond with func-tionalized groups of the sorbent and thus can highly enhance therecognition performance.

The FT-IR spectra of DMISNPs after dummy template extractionwere shown in Fig. 3S. As sol-gel has high water absorbance capac-ity, a broad absorbance band was observed at 3300 cm�1, which isattributed to OAH stretching of the adsorbed water on/intoDMISNPs structure. The absorption bonds at around 1400–1650 cm�1 indicate CAN stretching (Atakay et al., 2012). Theabsorption asymmetric stretching of CAH bonds was seen at2938 and 790 cm�1, while peaks related to NAH group appear at1559 and 2945 cm�1 (Silva & Augusto, 2006). The absorbancepeaks at 970 cm�1 and 1090 cm�1 correspond to SiAOH groupsand silicate groups (SiAO), respectively. These results indicatethe location of amine groups in the sol-gel network, which couldgenerate hydrogen bonds with analyte.

From the DMISNPs morphological structure characterized byTEM and SEM (Fig. 1), an average diameter of around 85 nm wasobtained in addition to its high porosity, uniformity and sphericalshape. Therefore, it is suitable as packing material. Moreover, theprepared monodisperse and low dimension silica nanoparticleswith extremely high surface-to-volume ratio (Peng et al., 2010)

lead to increase in the extraction efficiency. Satisfactory diametercause dummy template removal occurred completely and highlyrecognition cavity obtained. In addition, mass transfer wasincreased which causes high extraction efficiency.

3.2. Adsorption studies

Acrylamide with functional groups like amide is able to formstrong hydrogen bond between acrylamide and APTMS (Fig. 4S).The adsorption capacity of the present sorbent was calculatedusing Eq. (1):

Q ¼ ðC0 � CrÞV=M� 100 ð1Þwhere C0 and Cr are the acrylamide concentrations before and afterthe adsorption, V (L) is the volume of acrylamide solution, and M (g)is the mass of DMIPSNPs or NIPSNPs. The capacity of DMIPSNPs forthe adsorption of acrylamide was higher than that of NIPSNPs at thesame concentration, which may be due to the imprinting effect(Table 2S). The imprinted cavities and specific binding sites wereformed in predetermined orientation.

Table 1Analysis of variance (ANOVA) for central composite design.

Source Sum ofsquare

Degree offreedom

Meansquare

F value P value

Model 1241.86 9 137.98 59.98 <0.0001X1 47.61 1 47.61 20.69 0.0011X2 72.25 1 72.25 31.40 0.0002X3 554.60 1 554.60 241.07 <0.0001X1X2 14.58 1 14.58 6.34 0.0305X1X3 126.41 1 126.41 54.94 <0.0001X2X3 6.48 1 6.48 2.82 0.1242X12 238.44 1 238.44 103.65 <0.0001

X22 96.39 1 96.39 41.90 <0.0001

X32 7.305E�003 1 7.305E�003 3.175E�003 0.9562

Lack of Fit 1597 5 3.19 2.27 0.1945Pure Error 7.03 5 1.41Total error 1264.87 19

ig. 2. Response surface (a) sample:sorbent ratio-eluent volume (b) eluent volume-ashing volume (c) sample:sorbent ratio-washing volume.

M. Arabi et al. / Food Chemistry 210 (2016) 78–84 81

3.3. Optimization of the MIP-MSPD procedure

Variables such as the type of sorbent, sample-to-sorbent ratioand washing and elution conditions are the key factors that controlthe efficiency of the extraction and purity of the final extract. Con-ventional reversed phase materials such as C8, C18 are usually non-selective while the amino functionalized silica nanoparticles(MSPD) lead to significant improvement in figures of merit of acry-lamide extraction. To ensure the full description of the optimiza-tion approach, the composition of washing and eluent materialshas been primarily investigated through univariate method.

Since processed foods are complex samples, a washing stepbefore the elution is usually required in order to leave target com-pounds adsorbed on the cartridge and remove matrix interferencefrom the sample as much as possible. It is critical for processedfood samples to apply a washing step after the extraction whichsurely avoids the pollution of the analytical C18 HPLC column bythe protein. In this section, different washing solvents (hexane,DIW, acetone, ethyl acetate) were applied and their effects wereinvestigated. In all cases, ACN/methanol (5:5 v:v) was employedas an elution solvent. In these experiments, the cleanest extractsand the best recoveries (89–93%) were achieved using hexane aswashing solvent. Because of the hydrophilicity of DMISNPs andhigh potential of hexane to solve non-polar compounds, theremaining of long chain fatty acids is avoided and thus efficientlydisappears the overlap between peaks and the target analyte inchromatographic analysis. In other words, the most matrix inter-faces were washed with hexane without fracture the interactionsbetween acrylamide and sorbent. It can be considered as a success-ful clean-up procedure for fatty acids when there is no residual oilymatter on the bottom of the glass tube after the eluent is driedunder vacuum. Therefore, hexane was selected as the washing sol-vent for the subsequent experiments.

The selection of elution solvent is a function of analyte polarity,since the target analytes should be efficiently desorbed while theremaining components should be retained in the column. The effectof eluting solvent type on the recoveries was studied. In this study,methanol and acetonitrile were tested, according to the principlesof green chemistry, to avoid halogenated solvents. Therefore,methanol was used as the selective washing solvent at first, whilelow recoveries obtained for methanol is due to its strong elutionstrength. The mixtures of acetonitrile�methanol (acetonitrile con-tent ranging from 0% to 50% v:v%) were tested and recoveries wereincreased up to 91%.Moreover, the drying time of the extract was aslow as about 30 min. Indeed, methanol and acetonitrile are polarsolvents which are able to break hydrogen bonds between acry-lamide and amine group of APTMS present in the silica nanoparti-cles cavities. Eluent and washing volumes effects were studied

using central composite design. Based on the results obtained, ace-tonitrile:methanol (5:5) was selected as eluent solvent.

3.3.1. Central composite designIn this model, 20 random experiments were selected to

minimize the effect of uncontrolled variables (Fig. 5S andTable 3S) including sample-to-dispersant ratio (X1), eluent solventvolume (X2) and washing solvent volume (X3). The main factors

Fw

Fig. 3. The chromatograms of the biscuit samples (a) the blank biscuit (b) spiked biscuit (1.0 lg g�1).

Table 2Linearity, LOD, LOQ, precision and accuracy of the MSPD-HPLC/UV method.

Sample Linear range (lg g�1) R2 LOD (ng g�1) LOQ (ng g�1) Recovery (%)

Spiked sample (lg g�1) Intra-day (n = 5)-RSD (%) Inter-day (n = 5)-RSD (%)

Biscuit 0.05–5.0 0.999 16.1 40.1 0.05 89.2–1.94 94.0–3.040.2 93.5–1.72 83.7–3.531.0 98.4–4.86 96.4–6.725.0 99.6–4.67 99.3–5.81

Bread 0.05–5.0 0.9982 14.5 40.5 0.05 86.0–2.32 90.0–4.960.2 94.3–2.90 96.5–6.231.0 92.6–1.23 98.0–3.225.0 95.9–2.57 91.6–3.24

82 M. Arabi et al. / Food Chemistry 210 (2016) 78–84

and quadratic effects were evaluated to find the most importanteffects and their interactions. The effect of critical factors, interac-tions and model efficiency was investigated by the analysis of vari-ance (ANOVA). As seen from Table 1, P values less than 0.05 and Fvalues more than 0.05 indicate the statistical significance of corre-sponding terms in the polynomial equation within 95% confidencelevel. The model F-value (59.98) and a very low p-value (lessthan < 0.0001) implied that the model was highly significant forthe acrylamide adsorption by DMISNPs. Coefficient of determina-tion (R2 = 0.9818) indicates a good relationship between the exper-imental data and the fitted model. Analysis of results wasevaluated by plotting ER (%) versus significant variables usingRSM (Fig. 2). RSM figures show the interaction between quadraticfactors. A suitable sample-to-dispersant ratio allows completeadsorption of the sample components, which causes an increasein the interface area between the analyte and dispersant. The sam-ple and dispersant blended without sea sand and packed into thecartridge frit with barred pores lead to too high backpressure forc-ing the solvent to flow through the cartridge. Addition of sea sandmore over decreasing backpressure it improved the sample disrup-tion. As shown in Fig. 2a–c, at low eluent volume, less sample:sor-bent ratio and high washing volume, the ER% is low. As seen fromFig. 2a and b, the increase in eluent volume does not affect the ER%,significantly. 1.5 mL hexane was enough to remove most interfer-ences and it was shown that further increase in the washing sol-vent volume gives no improvement in recovery. As seen fromTable 1 and Fig. 6Sa (Pareto chart), all p-values of X1, X2, X3,X1X2, X1X3, X1

2 and X22 variables are less than 0.05, indicating the

significant influence of these variables on the acrylamide adsorp-tion. The highest ER% was obtained at high eluent volume(2.5 mL), low washing volume (1.5 mL), and mid sample:sorbentratio (1:1.5). A semi-empirical expression for the evaluation of ER% was achieved as follows:

y ¼ 80:22� 1:73X1 þ 2:12X2 � 5:89X3 � 1:35X1X2

þ 3:98X1X3 � 0:9X2X3 � 3:08X21 þ 1:96X2

2 � 0:017X23 ð2Þ

The adequacy of Eq. (2) was also expressed by comparing theexperimental and model predicted values for the acrylamideadsorption. As shown in Fig. 6Sb, the predicted values are quiteclose to the actual experiment, confirming that the regressionmodel exhibits excellent stability for analyte adsorption byDMISNPs.

3.4. Comparison of DMIPSNPs-MSPD and NIPSNPs-MSPD

The selectivity and extraction efficiency of the developedDMIPSNPs–MSPD procedure were investigated and compared withNIPSNPs–MSPD. For this aim, the optimum conditions for theDMIPSNPs–MSPD method were applied for the extraction of acry-lamide in biscuit sample using the NIPSNPs instead of DMIPSNPs asdispersant with recoveries between 39% and 60%. These resultsconfirm that the DMIPSNPs are much more efficient than NIPSNPsfor the adsorption of acrylamide.

3.5. Validation of the MIP–MSPD procedure

A calibration curve was established for acrylamide to coverwide concentration range of 0.05–5.0 lg g�1 with regression coef-ficients (R2) higher than 0.999.

To evaluate the applicability of the optimized DMIPSNPs-MSPD-HPLC-UV procedure for the analysis of biscuit and bread samples,the accuracy and precision of the method were examined usingspiked blank biscuit and bread samples at four concentration levels(0.05, 0.2, 1 and 5 lg g�1). No background of acrylamide found inthe blank samples (Fig. 3) leads to reasonable average recoveriesin the range of 83.7–99.6% for biscuit and 86.0–98.0% for bread,

Table 3Comparison of different methods for determination of acrylamide with proposed method.

Method Linear range (lg L�1) LOD (lg kg�1) Recovery (%) References

SPE-HPLC/UV 50–2000 23 78 Albishri and El-Hady (2014)

Ultrasonic-assisted-HPLC/UV 15–4500 25 106.6 ± 6.6 Shi et al. (2009)

Ultrasonic-assisted-HPLC/UV 80–1800 25 90.6–109.8 Wang et al. (2008)

MSPD-HPLC/UV 50–5000 16.1 (biscuit) 83.7–99.3 Present work50–5000 14.5 (bread) 90.0–98.0

M. Arabi et al. / Food Chemistry 210 (2016) 78–84 83

while their intra-day and inter-day precisions expressed as relativestandard deviation (RSD) were obtained to be between 1.72% to6.72% and 1.23% to 6.23% for biscuit and bread, respectively. Theseresults demonstrated the well repeatability and accuracy of themethod. LOD and LOQ were calculated using 3r/slope and 10r/slope ratios, respectively, where r is the standard deviation ofthe mean value for 10 chromatograms of the blank determinedaccording to the IUPAC recommendations (Committee, 1987) andlisted in Table 2.

4. Conclusions

In this paper, a novel strategy for the synthesis of dummymolecularly imprinted silica nanoparticles with high selectivityversus acrylamide was successfully developed. The presentmethod benefits from advantages like high binding capacity, com-plete template removal, and high affinity compared to the conven-tional MIPs in addition to the higher adsorption capacity of theproposed silica nanoparticles successfully employed as dispersantsorbent in MSPD method. Moreover, the high selectivity and affin-ity toward acrylamide have effectively eliminated the template-bleeding problem. The method was shown to be simple, easy,highly efficient and fast. This method extremely lowers the con-sumption of toxic organic solvents. Finally, comparing this methodwith others (Table 3) the feasibility of MINPs-MSPD–HPLC in termsof characteristic performance is confirmed (Albishri & El-Hady,2014; Shi et al., 2009; Wang et al., 2008).

Acknowledgement

The authors express their appreciation to the Graduate Schooland Research Council of the University of Yasouj for financial sup-port of this work.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.foodchem.2016.04.080.

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