Extraction and on-fiber Derivatization of Chlorophenols in Leather by Internally Cooled Solid Phase Microextraction

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1 J. Brz. Chem. Soc., Vol. 23, No. 12, , Printed in Brzil Sociedde Brsileir de Químic $ Article Extrction nd on-fiber Derivtiztion of Chlorophenols in Lether by Internlly Cooled Solid Phse Microextrction Cristine D. de Souz Silveir, Josis Merib, Edmr Mrtendl b nd Edurdo Crsek*,,c Deprtmento de Químic, Universidde Federl de Snt Ctrin, Florinópolis-SC, Brzil b Deprtmento de Químic, Universidde do Estdo de Snt Ctrin, Joinville-SC, Brzil c Instituto Ncionl de Ciênci e Tecnologi de Bionlític, CP 6154, Cmpins-SP, Brzil Neste estudo é proposto um novo procedimento nlítico pr determinção de fenóis em mostrs de couro utilizndo técnic de microextrção em fse sólid refrigerd internmente (CF-SPME) com derivtizção diret n fibr e cromtogrfi gsos copld espectrometri de msss com monitormento de íons seleciondos (GC-SIM-MS). As condições experimentis pr extrção e derivtizção form otimizds utilizndo procedimentos quimiométricos, sendo tempo de extrção e tempertur d mostr de 5 min e 170 ºC, tempertur do recobrimento d fibr de 20 ºC, e exposição d fibr o hedspce de 70 µl do gente derivtiznte bis(trimetilsilil) trifluor-cetmid por 23 min. Limites de detecção vrirm entre 1,03 e 2,68 µg g -1 e o desvio pdrão reltivo (RSD) foi menor que 15% (n = 5). Estudos de recuperções em três níveis de concentrção vrirm entre 64,5 e 92,3%. This study proposes new nlyticl procedure bsed on n internlly cooled solid phse microextrction technique (CF-SPME) combined with on-fiber derivtiztion nd gs chromtogrphy-selected ion monitoring-mss spectrometry (GC-SIM-MS) for the determintion of phenols extrcted directly from lether smples. The extrction nd derivtiztion conditions were optimized using experimentl designs, such s: extrction time nd smple temperture of 5 min nd 170 ºC, fiber recot temperture of 20 ºC, nd exposing the fiber to the hedspce of 70 µl of bis(trimethylsylyl)trifluoro-cetmide derivtizing gent for 23 min. Detection limits rnging from 1.03 to 2.68 µg g -1 nd reltive stndrd devition (RSD) lower thn 15% (n = 5) were obtined. The recovery ws studied t three concentrtion levels nd excellent recoveries rnging from 64.5 to 92.3% were obtined. Keywords: cold fiber SPME, phenols, lether, gs chromtogrphy-mss spectrometry, experimentl designs Introduction Phenols nd their derivtives hve been widely used in the industril sector for some time, but in recent decdes their use hs been restricted due to their high toxicity nd the potentil hzrd they represent to humn helth. 1 These compounds re frequently found in tp nd surfce wters, soils nd effluents originting from the production of lether, pint, petroleum, pesticides, cellulosic pulp nd pper, nd even in some mnufctured products. 2 The development of sensitive nlyticl methods for the determintion of contminnts in solid mtrices originting from industril processes represents considerble *e-mil: edurdo.crsek@ufsc.br chllenge due to the strong interction between the nlyte nd the mtrix. The nlyticl methods commonly proposed include supercriticl fluid extrction, 3 liquid extrction 4 nd solid phse extrction. 5,6 However, the bove-mentioned methods hve disdvntges such s being of high cost nd time-consuming, nd they often require the use of lrge volumes of orgnic solvents. Considering tht smple preprtion is usully the most time-consuming step nd genertes lrger error in instrumentl nlysis, smple preprtion methods chrcterized by simplicity, reproducibility, low use of orgnic solvents nd effective in terms of smple clen-up hve been developed. Smple preprtion techniques such s solid phse microextrction, stir br sorptive extrction, liquid phse microextrction, dispersive liquid-liquid microextrction

2 Vol. 23, No. 12, 2012 Silveir et l nd liquid liquid liquid microextrction hve been employed to extrct contminnts from solid mtrices. 6 A smple preprtion method tht hs been successfully pplied in the determintion of voltile orgnic compounds in the hedspce of complex mtrices is internlly cooled SPME. Cold fiber solid phse microextrction technique (CF)-SPME hs been employed in the extrction of poly-cyclic romtic hydrocrbons (PAHs) from soil nd sediment smples, 7 frgrnces from Irnin rice smples 8 nd off-flvor compounds in cork stopper smples 9 s well s to determine the rom profile of tropicl fruits. 10 Physico-chemicl studies to investigte the desorption kinetics of PAHs from solid smples 11 nd photodegrdtion products of hexchlorobenzene 12 hve lso been crried out using CF-SPME. Bsiclly, in the cold fiber method the fiber is mintined t low temperture in the hedspce of the smple heted to high tempertures. Heting the smple to n elevted temperture increses the relese of nlytes from the mtrix incresing their concentrtion in the hedspce, while the use of lower fiber temperture overcomes the exothermic consequences of SPME nd thus increses the nlyte/fiber coting prtition coefficient. In this study, the use of CF-SPME technique in hedspce mode (CF-HS-SPME) followed by on-fiber derivtiztion for direct nd exhustive extrction of phenols from lether is reported. To ssure the best extrction nd derivtiztion conditions, the CF-HS-SPME system ws optimized using experimentl design procedures. Experimentl Chemicls nd regents Certified stndrds of phenols [phenol (P), 2-methylphenol (2MP), 4-methylphenol (4MP), 3-methylphenol (3MP), 2-chlorophenol (2CP), 3-chlorophenol (3CP), 4-chlorophenol (4CP) 2,4-dimethylphenol (2,4dMP)] were obtined t concentrtions of 2000 mg L -1 in methnol (Supelco, Bellefonte, USA). Working solutions were prepred by diluting stock solutions with methnol (Sigm Aldrich, Steinheim, Germny). Bis(trimethylsylyl) trifluoro-cetmide (BSTFA) (Supelco, Bellefonte, USA) ws used for the derivtiztion procedure. Wet blue lether smples were supplied by the Instituto Brsileiro de Tecnologi do Couro e Arteftos (Novo Hmburgo, Rio Grnde do Sul, Brzil). Instrumenttion All of the chromtogrphy nlyses were crried out using Shimdzu GC-MS QP 2010 Plus instrument. The Rtx-5MS column (30 m 0.25 mm 0.25 µm) mnufctured by Restek (Bellefonte, PA, USA) ws used for the GC seprtion. Helium (99.999%) ws used s the crrier gs t flow rte of 1.69 ml min -1. The injections were performed in the splitless mode during the first minute of the chromtogrphic run, followed by split rtio of 1:100. The initil oven temperture ws 50 ºC which ws incresed t 5 ºC min -1 to 200 ºC. The injector temperture ws 290 ºC nd the fiber desorption time ws 10 min. Desorption conditions were fixed so tht no memory effects were observed. The trnsfer line nd the ion source tempertures were set t 200 nd 210 ºC, respectively. The ioniztion ws crried out in SIM mode to increse the detection selectivity nd sensitivity. The ions selected for the quntifiction nd identifiction of the trget nlytes in their derivtive form (m/z rtio) were: (2MP, 4MP, 3MP), (3CF, 4CP), (2CP), (P), (2,4dMP). The cold fiber device, temperture controller nd solenoid vlve used in this study hve been described in previous ppers A poly-dimethyl siloxne (PDMS) hollow membrne with 178 mm wll thickness nd 1 cm length ws used s the extrction phse. Liquid CO 2 ws used to cool the fiber coting. The smple temperture ws controlled using heter device especilly built to crry out the CF-SPME studies (Dist, Florinópolis, Brzil). All mnipultions of the cold fiber device s well s the chnging of the fiber tempertures were crried out mnully. Lether smple preprtion All of the extrctions were crried out in the hedspce mode. Lether smples (100 mg) free of the trget nlytes were cut into cubes of pproximtely 2 mm 2 nd dded to 15 ml vils. The smples were spiked with 4 µl of the phenol stndrd solution (400 mg L -1 ) nd left for t lest 24 h t 4ºC to llow strong interctions between the smple mtrix nd nlytes to occur. CF-HS-SPME procedure The vil contining the smple ws introduced into the heter device t the pproprite temperture (selected ccording to the experimentl optimiztion design procedure). Subsequently, the CF-HS-SPME device ws mnully inserted into the seled vil through the septum nd the fiber ws exposed to the smple hedspce for the specified extrction time. Following the smpling procedure, the CF-HS-SPME fiber ws inserted into the hedspce of seled 4 ml vil contining the BSTFA gent under constnt gittion. The exposure time nd

3 2234 Extrction nd on-fiber Derivtiztion of Chlorophenols in Lether by CF-SPME J. Brz. Chem. Soc. BSTFA volume ws defined ccording to the experimentl design procedure. After these two steps, the fiber ws immeditely inserted into the GC-MS injector nd the nlytes were thermlly desorbed from the fiber for 10 min t 290 ºC. Optimiztion strtegy The optimiztion of the extrction procedure ws crried out in two steps. In the first step the vribles smple temperture ( C), extrction time (5-25 min) nd fiber temperture (5-30 C) were evluted by two-level full fctoril design. In second step the fiber temperture (10-50 C) ws optimized by univrite procedure. For both steps the procedure ws crried out using BSTFA t 50 µl nd 15 min of fiber exposure to the hedspce of the derivtive gent. The vribles derivtive gent volume ( µl) nd time of exposure to the hedspce of the BSTFA (5-30 min) were optimized through Doehlert design. The geometric men for the pek re of phenols ws used s the experimentl dt for processing using the Sttistic 6.0 computer progrm. All experiments were crried out in duplicte except for the center point (triplicte). Evlution of quntittive extrction of phenols from lether using CF-HS-SPME In order to evlute whether the extrction using the CF-HS-SPME technique is exhustive, study ws crried out by pplying the optimized procedure to the sme smple twice. The bsolute recoveries were clculted using the eqution R = (1-n 2 )/n 1, where n 1 nd n 2 re the pek res corresponding to the first nd second extrction, respectively. After the first extrction procedure the fiber ws removed from the smple vil nd inserted into the derivtizing gent vil. After the therml desorption of the nlytes in the GC injector port, the cold fiber system ws inserted gin into the sme smple vil which hd been kept in the ice bth, nd this vil ws then reintroduced into the heter block. When the smple temperture stbilized t the selected vlue, the fiber ws exposed to the smple hedspce nd the procedure described bove ws repeted. Results nd Discussion The procedure used in this study to optimize the proposed method consisted of two steps. The first, focused on obtining the best experimentl conditions to extrct phenols from lether using the CF-HS-SPME procedure. The second step focused on the derivtiztion procedure using the derivtizing gent BSTFA. In both cses experimentl designs were used. Finlly, the nlyticl performnce prmeters for ll trget compounds using the method developed were determined. Optimiztion of CF-HS-SPME procedure A two-level 2 3 full fctoril design with centrl point ws pplied to determine the influence of selected fctors (extrction time, smple temperture nd fiber temperture) nd their interctions in the CF-HS-SPME system. Figure 1 shows the min effects nd their interctions, ccording to the full fctoril design, with the smple nd fiber tempertures being highly significnt s well s the interction between them. On the other hnd, by considering the set conditions within the experimentl domin the extrction time ws not significnt nd thus it ws fixed t 5 min for ll experiments. However, ccording to the fctoril study, on incresing the smple nd fiber tempertures the recovery efficiency improves. As the smple temperture t the high level (170 C) of the experimentl design ws lredy very high vlue, nd to minimize leking of the nlytes, this vrible ws fixed t 170 C. Since the interction between the smple nd fiber tempertures ws significnt nd the curve indictes tht the response is not liner in the rnge evluted, finl optimiztion of the fiber temperture ws crried out with univrite procedure. The results obtined in this study indicted tht the optimum fiber temperture is 20 C, s shown in Figure 2. Figure 1. Results obtined for the full fctoril 2 3 design crried out for the optimiztion of the vribles (1) fiber temperture, (2) extrction time nd (3) smple temperture. Optimiztion of derivtiztion procedure The reltionship between the time of exposure of the fiber to the derivtizing gent vpor nd the volume of BSTFA ws observed using the Doehlert mtrix nd the

Vol. 23, No. 12, 2012 Silveir et l. 2235 Tble 1. Successive extrctions of phenols from the lether Figure 2. Results obtined for the optimiztion of fiber temperture.

4 Vol. 23, No. 12, 2012 Silveir et l Tble 1. Successive extrctions of phenols from the lether Figure 2. Results obtined for the optimiztion of fiber temperture. surfce response is presented in Figure 3. The volume of the vil ws fixed t 4 ml. The findings of this study suggest reltionship between the vribles investigted. By nlyzing the response surfce, the optimum derivtiztion conditions tht generte the best signl for ll trget nlytes corresponded to n exposure time of 23 min nd 70 µl of BSTFA. Anlyte Recovery of first extrction / % Recovery of second extrction / % P MP MP MP CP CP ,4dMP CP used for this purpose. Tble 2 summrizes the results obtined for some prmeters of merit when using the procedure described in section 2.4. The limits of detection nd quntifiction were clculted s three nd ten times the signl to noise rtio, respectively. Good correltion coefficients were obtined in the studied liner rnge (3.42 nd 80 µg g -1 ) with R vlues of t lest Detection limits were stisfctory, being close to those obtined in other studies reported in the literture for the determintion of phenols in solid mtrices such s lether nd wood. The precision of the proposed method ws verified through five lether smples spiked with phenols t 20 µg g -1 with results rnging between 8.28 nd 15.48% (Tble 2). Tble 2. Anlyticl figures of merit obtined for the optimized CF HS SPME method Figure 3. Response surfce obtined using Doehlert design for the optimiztion of the BSTFA volume nd time of exposure of the fiber to the derivtizing gent BSTFA. Quntittive extrction of phenols from lether New informtion on exhustive extrction using the CF-SPME procedure ws explored in this study. In this regrd the mount of nlyte present in second extrction of the sme smple (100 mg of lether t 20 µg g -1 ) ws determined. The results of the successive extrctions, shown in Tble 1, illustrte tht the exhustive extrction (75 85%) of phenols from lether occurred using the optimized conditions in the first extrction. This is very interesting feture of the method, s it fcilittes the clibrtion procedure nd improves its ccurcy. Anlyticl performnce prmeters A clibrtion curve ws constructed for the phenols investigted in this study under the optimum CF-HS-SPME nd derivtiztion conditions. A blnk lether smple ws Anlytes Liner rnge / (µg g -1 ) R LOD b / (µg g -1 ) RSD c / % P MP MP MP CP CP ,4dMP CP R: correltion coefficient; b LOD: limit of detection; c RSD: reltive stndrd devition (n = 5). Three lether smples were submitted to the newly developed CF-HS-SPME method, nd the trget compounds were not detected in significnt mounts, probbly becuse the use of these compounds in lether tretment hs been restricted in Brzil since Thus, the smples were spiked with the trget phenols t three concentrtion levels (20, 40 nd 80 µg g -1 ) nd the recovery ws compred

5 2236 Extrction nd on-fiber Derivtiztion of Chlorophenols in Lether by CF-SPME J. Brz. Chem. Soc. with the clibrtion curve obtined using blnk lether smple. Excellent recoveries (in the rnge of %) were obtined, indicting tht the method is relible for the determintion of these compounds in lether smples (Tble 3). Tble 3. Study on recovery of phenols using three levels of phenol concentrtion in lether smples Anlytes Despite the trget nlytes were not detected in lether smples nlyzed in this study, the developed method is vluble becuse of this nlysis is requisite for exporting of lether-bsed products (such s shoes nd hndbgs) in order to ssure tht these products re phenols-free. Therefore, the nlysis of the mtrix/nlytes proposed in this study is essentil for exporting requirements, such s for the Europen Community. Furthermore, the prohibition of use is not gurntee tht these compounds hve not been used underhnd. The development of this method cme from rel necessity, since conventionl method to determine phenols in lether is bsed on Soxhlet, which requires lrge volume of solvents nd time for nlysis. Conclusions Level 1 (20) Level 2 (40) Level 3 (80) Recovery / % P MP MP MP CP CP ,4dMP CP Unit: µg g -1. The method using CF-HS-SPME nd on-fiber derivtiztion ws shown to be sensitive, precise nd ccurte. Furthermore, this is simple nd very fst method requiring only smll mounts of smple nd no pre-tretment of complex smples prior to the extrction procedure. Acknowledgements The uthors re grteful to CNPq for the finncil resources which mde this reserch possible. CNPq is lso cknowledged for providing doctorl fellowship to C. D. S. S. nd reserch fellowship to E. C. References 1. Buchholz, K. D.; Pwliszyn, J.; Anl. Chem. 1994, 66, Fvro, G.; De Leo, D.; Tstore, P.; Mgno, F.; Bllrdin, A.; J. Chromtogr. A 2008, 1177, Chen, J-L.; Liu, C-Y.; Anl. Chim. Act 2005, 528, Gneshjeevn, R.; Chndrsekr, R.; Kdigchlm, P.; Rdhkrishnn, G.; J. Chromtogr., A 2007, 1140, Mrtínez-Uruñuel, A.; Rodríguez, I.; Cel, R.; Gonzáles-Sáiz, J. A.; Pizrro, C.; Anl. Chim. Act 2005, 549, Moris, P.; Stoichev, T.; Clr, M.; Bsto, P.; Vsconcelos, M. T. S. D.; Tlnt 2012, 89, Ghisvnd, A. R.; Hosseinzdeh, S.; Pwliszyn, J.; J. Chromtogr., A 2006, 1124, Ghisvnd, A. R.; Setkov, L.; Pwliszyn, J.; Flvour Frgr. J. 2007, 22, Crsek, E.; Cudjoe, E.; Pwliszyn, J.; J. Chromtogr., A 2007, 1138, Crsek, E.; Pwliszyn, J.; J. Agric. Food Chem. 2006, 54, Hdddi, S. H.; Niri, V. H.; Pwliszyn, J.; Anl. Chim. Act 2009, 652, Snchez-Prdo, L.; Risticevic, S.; Pwliszyn, J.; Psillkis, E.; J. Photochem. Photobiol. 2009, 206, Resolution RDC No. 164 from the Ntionl Helth Surveillnce Agency (ANVISA), Prohibition nd the Use of the Active Ingredient Pentchlorophenol nd its Slts, August, 2006, Brsíli, DF, Brsil. Submitted: July 12, 2012 Published online: Jnury 16, 2013 FAPESP hs sponsored the publiction of this rticle.

Article. Manoochehr Bahmaei,*,a Hossein Ali Mashayekhi b and Faezeh Khalilian c. Introduction

Article. Manoochehr Bahmaei,*,a Hossein Ali Mashayekhi b and Faezeh Khalilian c. Introduction Article A http://dx.doi.org/10.5935/0103-5053.20150116 J. Brz. Chem. Soc., Vol. 26, No. 7, 1475-1481, 2015. Printed in Brzil - 2015 Sociedde Brsileir de Químic 0103-5053 $6.00+0.00 Appliction of Ultrsound-Assisted