Departamento de Química, Universidade Federal de Roraima, Boa Vista-RR, Brazil

Transcription

1 Article J. Brz. Chem. Soc., Vol. 27, No. 4, , Printed in Brzil Sociedde Brsileir de Químic $ Acid Decomposition of Yerb Mte (Ilex prguriensis) Using Reflux System for the Evlution of Al, C, Cd, Cr, Cu, Fe, K, Mg, Mn, N, Pb nd Zn Contents by Atomic Spectrometric Techniques Cmil C. Pereir, Alexnder O. Souz, Eliézer Q. Oreste, Mirl J. A. Cidde, b,c Solnge Cdore, c Anderson S. Ribeiro nd Mrin A. Vieir*, Lbortório de Metrologi Químic (LbMeQui), Universidde Federl de Pelots, Cpão do Leão-RS, Brzil b Deprtmento de Químic, Universidde Federl de Rorim, Bo Vist-RR, Brzil c Instituto de Químic, Universidde Estdul de Cmpins, CP 6154, Cmpins-SP, Brzil In the first prt of this pper, two cid decomposition procedures for the determintion of Al, C, Fe, Mg, Mn nd Zn contents in yerb mte smples by inductively coupled plsm opticl emission spectrometry (ICP OES) were compred. Using reflux system, the smples were treted with mixture of HNO 3 nd H 2 O 2 for 3 hours t 220 C in the digester block. The results from five commercil yerb mte smples were compred with the results obtined from microwve digestion. Good greement between the procedures t 95% confidence level ws obtined with reltive stndrd devition (RSD) vlues lower thn 10.0%. The ccurcy ws evluted using ddition nd recovery experiments (80.5 to 112.8%). In the second prt, C, Cd, Cr, Cu, Fe, K, Mg, N, Pb nd Zn concentrtions were evluted in the yerb mte infusion. The results showed tht elements such s N, K, Mg nd Zn re esily trnsferred to the hot wter used for the infusion. For Pb nd Cd, the concentrtions found in the nlyzed smples were lower thn the vlues estblished by Brzilin legisltion. Keywords: cid decomposition, reflux system, yerb mte, spectrometric techniques Introduction Yerb mte (Ilex prguriensis) is widely consumed in Southern Brzil (Rio Grnde do Sul, Snt Ctrin nd Prná sttes) nd lso in prts of Uruguy, Prguy nd Argentin, minly in the form of mte (clled chimrrão ), which is obtined through the continuous ddition of hot wter to ground yerb mte. Another method of consumption is s te vi the simple ddition of hot wter to the dried leves of this plnt. 1-3 Yerb mte hs certin defining chrcteristics, such s bitter tste. It lso hs therpeutic properties, cting s n ntioxidnt, n ntirheumtic, diuretic, glycogenolytic nd lipolytic. 4 The Union of Industry Mte in the Stte of Rio Grnde do Sul (RS-Sindimte) colltes sttisticl dt on the yerb mte mrket nd reported tht more thn 82 thousnd hectres were plnted in 2012, leding to production of over 513,000 tons of yerb mte. In tht sme yer, over *e-mil: mrinvieir@pq.cnpq.br 62 million tons were exported. The dt from 2013 show n increse of pproximtely 26% in exporttion with Rio Grnde do Sul exporting more thn ny other Brzilin stte (pproximtely 74% of the vlue for 2013). It produces the most yerb mte s well. 5 Due to the high consumption of yerb mte in the country, the need for qulity control is importnt, primrily in the form of evluting the chemicl composition of the products tht rech the mrketplce. This evlution is prticulrly relevnt becuse mte consists of leves nd twigs tht re regulrly removed, cusing the producers to replce some of the lost nutrients to ensure qulity nd productivity. 6 To determine the content of inorgnic elements in yerb mte, it is necessry to pply suitble smple preprtion method with dequte sensitivity nd ccurcy. 7,8 A method widely employed for the preprtion of orgnic smples is cid decomposition, which involves the use of strong oxidizing minerl cids nd cn be performed using both open nd closed systems. There re certin disdvntges of open systems, including nlyte losses nd/or regent

2 686 Acid Decomposition of Yerb Mte (Ilex prguriensis) Using Reflux System J. Brz. Chem. Soc. voltiliztion cused by the high tempertures used in the decomposition process. 8 Moreover, the literture reports some studies using perchloric cid (HClO 4 ) for the decomposition of yerb mte smples, but these procedures require creful hndling becuse perchloric cid is strong oxidizer nd cn cuse explosions. 1,9-11 Thus, lterntive methods hve been developed to void the use of this cid, especilly in Brzil, where its cquisition is controlled by the government. Closed systems re n lterntive tht cn ddress the disdvntges of open systems. Digestion ssisted by microwve rdition hs been widely used for vrious smple types. 8,12-14 In ddition to conventionl methods, reflux systems for cid decomposition hve recently been pplied, providing stisfctory results for the determintion of metl nd voltile elements in different smples This reflux system is efficient due to the condenstion of the generted vpors inside the flsk, which minimizes nlyte/cid loss due to voltiliztion when high temperture is used in the digester block. For the determintion of metls in different types of smples, the literture reports vrious nlyticl techniques bsed on tomic spectrometry. 12 Techniques bsed on inductively coupled plsm re dvntgeous due to their pplicbility to multiple elements nd their sensitivity, nd they hve previously been pplied for the determintion of metls in yerb mte smples. 6,13,19 This work ims to evlute the decomposition products of yerb mte smples using reflux system s well s closed system ssisted by microwve rdition for the subsequent determintion of Al, C, Fe, Mg, Mn, N nd Zn contents by inductively coupled plsm opticl emission spectrometry (ICP OES) nd their concentrtions in the yerb mte infusion. Clcium nd Mg re importnt for the formtion of bones, teeth nd tissue elements nd lso help to mintin the growth nd functions of the body. 20 Mngnese hs dditionl importnt functions in humns, in tht it cn ct s n enzyme ctivtor nd is component of mny enzymes. The recommended dily intke of Mn is pproximtely 2 to 5 mg. 21,22 Iron is n essentil element becuse it is component in hemoglobin nd myoglobin nd plys key role in trnsporting oxygen to cells. Zinc cts s cofctor in over 200 metlloenzymes, which reflects its importnce for growth. 20,22 Experimentl Instrumenttion ICP OES Anlyticl mesurements of the Al, C, Fe, Mg, Mn nd Zn contents were performed using simultneous ICP OES instrument (PerkinElmer Optim 3000DV, Norwlk, USA) equipped with peristltic pump, cross-flow nebulizer coupled to Scott cmer nd cermic injector tube with 2.0 mm internl dimeter. This instrument hs solid-stte segmented rry chrge coupled device (SCD) detector nd cn operte in both the rdil nd xil torch configurtions. The entire system ws controlled using the PE Winlb softwre. Argon with purity of % (White Mrtins, São Pulo, Brzil) ws used for the nlyticl mesurements. The instrumentl conditions re shown in Tble S1. Prior to usge, check of the plsm conditions ws performed to obtin the best sensitivity for ll nlytes investigted. The choice of the emission line for Mn ws bsed on the signl to bckground for this element to obtin dequte sensitivity in ICP OES nlysis. Flme tomic bsorption spectrometry/flme tomic emission spectrometry (FAAS/FAES) Mesurements of the C, Cu, Fe, Mg nd Zn contents were crried out using flme spectrometer (PerkinElmer AAnlyst 200, Shelton, USA) equipped with deuterium bckground correction nd with flme of ir-cetylene. Hollow cthode lmps (Lumin, PerkinElmer) for ech element were used. Sodium nd K were lso determined in this spectrometer, but using emission mode. The instrumentl prmeters used followed the mnufcturer s recommendtions nd re shown in Tble S2. Grphite furnce tomic bsorption spectrometry (GF AAS) Mesurements for the Cd, Cr nd Pb contents were crried out using n tomic bsorption spectrometer (PerkinElmer PinAAcle 900Z, Shelton, USA) equipped with grphite furnce, n utosmpler (AS900 model) nd Zeemn-effect bckground corrector. All mesurements were mde in integrted bsorbnce, using trnsversely heted pyrolytic grphite coted tubes with L vov pltforms (PerkinElmer). The opertionl conditions recommended by the mnufcturer were employed. Hollow cthode lmps (Lumin, PerkinElmer) were used operting t 4 ma (Cd), 25 ma (Cr) nd 10 ma (Pb). The mesurements were performed t wvelengths of nm for Cd, nm for Cr nd nm for Pb with 0.7, 0.8 nd 0.7 nm spectrl bnd pth, respectively. Argon (99.996%, Linde, Brueri, Brzil) ws used s the protectnt nd purge gs. Plldium nd Mg were used s chemicl modifiers by dding 5 nd 3 µg into the grphite furnce for ech mesurement, respectively. The temperture progrm ws optimized nd is shown in Tble S3. The smples were weighed using n nlyticl blnce (Ohus Adventurer 2140, New Jersey, USA). For smple cid decomposition, heted digester block ws used

3 Vol. 27, No. 4, 2016 Pereir et l. 687 (MA-4025 model, Mrconi, Pircicb, Brzil). In ech digester tube, cold finger mde of glss (reflux system) ws introduced to void losses due to voltiliztion of the nlytes nd regents, s described in previous work. 16 An ETHOS 1 (Milestone, Sorisole, Itly) microwve digestion system equipped with closed polytetrfluoroethylene (PTFE) vessels nd sensors for temperture nd pressure control ws used for microwve smple tretment. Mterils nd regents Anlyticl grde regents were used for ll experiments. All solutions were prepred using high-purity wter with resistivity of 18.3 MΩ cm obtined from Direct-Q 3 Wter Purifiction System (Millipore Corportion, Bedford, USA). Working reference solutions of Al, Cd, Cr, Fe, N, Pb, Zn nd C, Mg nd Mn were prepred by dilution of stock solution contining 1000 mg L -1 or 4000 mg L -1 of ech nlyte, respectively, in 1% (v/v) HNO 3. Nitric cid (65%, v/v, Synth, Brzil) ws purified by double sub boiling distilltion in MA-075 qurtz system (Mrconi, Pircicb, Brzil). Hydrogen peroxide (30%, v/v, Merck, Drmstdt, Germny) ws lso used. For the nlysis of C using FAAS, Cs L chloride commercil buffer (Fluk, Buchs, Germny) ws used to void interferences. The concentrtion dded in the stndrds solutions nd smples ws 1% (v/v). Prior to usge, ll glss pprtuses were conventionlly wshed nd soked in 10% (v/v) HNO 3 for t lest 48 h nd then rinsed with ultrpure wter. Smples nd procedures To determine the nlyte concentrtions, ten commercil smples of yerb mte were cquired from locl mrket in Pelots city in the Southern region of Brzil. These smples were triturted using blender (non-contminting kitchen mixer) nd pssed through 0.25 mm sieve to obtin homogeneous smple. Studies were performed to verify the smpling error nd clculte the humidity content of the yerb mte smples. Approximtely 1 g of three different smples ws dried in n oven t 100 ºC until reching constnt weight to eliminte the humidity. All smples were prepred in triplictes nd were dried nd stored in desicctors until weighing for nlysis. The humidity content in ll smples verged 6.8 ± 0.3% (m/m). To determine the sh content, pproximtely 1 g of smple ws weighed directly into beker nd heted in muffle furnce t 600 C for one nd hlf hours. After this period, the bekers contining the shes were stored in desicctors until weighing. The sh content in ll smples verged 6.7 ± 0.6% (m/m). For ICP OES nlysis, the smples were prepred using two different procedures, s described below. Procedure 1: cid decomposition in n open system with cold finger Approximtely 500 mg of yerb mte ws weighed into digestion tube, nd 9.0 ml of 65% (v/v) HNO 3 ws dded. The reflux system ws coupled to the tubes, nd the mixture ws heted in digester block t 220 C for 2 h. After cooling to room temperture, 1.0 ml of 30% (v/v) H 2 O 2 ws dded, nd the solutions were heted gin for 1 h t 220 C. After cooling, the volume ws djusted to 50 ml using ultrpure wter for subsequent nlysis. Procedure 2: microwve digestion For this procedure, pproximtely 500 mg of smple ws ccurtely weighed into PTFE vessel. 5 ml of 65% (v/v) HNO 3, 2 ml of 30% (v/v) H 2 O 2 nd 4 ml of deionized wter were subsequently dded. The vessels were closed nd then plced inside the microwve oven, nd the digestion ws crried out ccording to defined heting progrm. This progrm hd the following steps: the smple ws initilly heted from room temperture to 80 C in 2 min, held t this temperture for 5 min, heted to 120 C in 4 min, held t this temperture for 5 min, heted to 200 C in 7 min, nd held t this temperture for 25 min. Subsequently, the smples were left to cool, trnsferred to individul 50.0 ml volumetric flsks, nd diluted with deionized wter for subsequent nlysis. For ech smple, this procedure ws crried out in triplicte. To evlute the vilbility of metls in yerb mte smples, experiments involving the nlysis of brley yerb mte (procedure 3) s well s the wter in contct with the yerb mte fter the process of infusion (procedure 4) were performed. Here, techniques such s FAAS, FAES nd GF AAS were employed, nd the smples were prepred vi cid decomposition in n open system with cold finger. The procedures 3 nd 4 re described below. Procedure 3: nlysis of brley yerb mte To determine the C, Cd, Cr, Cu, Fe, K, Mg, N, Pb nd Zn contents in the brley yerb mte, the mte ws prepred in glss bowl. Five different brnds/smples of yerb mte (F, G, H, I nd J) were used. The wter for the mte ws heted, nd the temperture ws mintined in 80 C (i.e., the idel temperture for hot mte). Approximtely 74 g of yerb mte ws dded to glss bowl. 1.6 L of wter ws dded to ech mte smple until the mte ws considered wek. Subsequently the yerb mte from the glss bowl ws tken out nd ws spred on wtch glsses (in triplicte for ech mte) nd plced in the oven t temperture of

4 688 Acid Decomposition of Yerb Mte (Ilex prguriensis) Using Reflux System J. Brz. Chem. Soc. 80 C. The smples were kept in the oven for 20 h to remove the humidity. After drying, the smples were homogenized due to the presence of twig frgments of yerb mte. The smples were decomposed following procedure 1, nd the volume ws djusted to 25 ml using ultrpure wter for subsequent nlysis. For ll smples, the concentrtions of the nlytes were determined by FAES (N nd K), FAAS (C, Cu, Fe, Mg, Zn) nd GF AAS (Cd, Cr, Pb). Procedure 4: nlysis of wter fter the infusion process To determine the mount of nlyte tht is extrcted from yerb mte by the hot wter, leching procedure ws performed, bsed on the study of Heinrichs nd Mlvolt. 6 Here, pproximtely 7 g of ech yerb mte smple ws weighed in beker, nd 100 ml of wter t 80 C ws dded. The mte ws kept in contct with wter for 15 minutes. Afterwrds, the wter ws seprted by filtrtion using qulittive filter with 12.5 cm dimeter nd 14 µm porosity. The resulting liquid ws directly nlyzed for the determintion of the following contents: N nd K by FAES; C, Cu, Fe, Mg nd Zn by FAAS; Cd, Cr nd Pb by GF AAS. Results nd Discussion Smple preprtion by cid decomposition The comprison between two decomposition procedures ws crried out using ICP OES nlysis, nd the concentrtions of Al, C, Fe Mg, Mn nd Zn were determined in five yerb mte smples (A, B, C, D nd E). Using the open system with cold finger, 5 ml of HNO 3 nd 1 ml of H 2 O 2 were initilly evluted for the decomposition of the yerb mte smples. However, it ws observed tht the finl solutions were turbid with high viscosities, nd consequently, their nlyses using ICP OES gve unstisfctory results with low precision. Thus, the volume of HNO 3 ws incresed to 9 ml to promote efficient decomposition nd produce clener finl solutions. Although this volume is lrger, the nlyticl results for the element concentrtions gree nd re comprble with the conventionl method for smple preprtion using microwve rdition. The method for smple preprtion using reflux system introduced in ech digester tube ws efficient for the decomposition of yerb mte smples, nd no loss of cid nd/or nlyte ws observed due to voltiliztion during heting becuse the temperture employed in the digester block ws higher thn the HNO 3 boiling point. This is extremely importnt becuse there is no need to replce the cid during the smple preprtion process, which would increse the concentrtion of the nlyticl blnk. Compred to microwve-ssisted digestion, the reflux system is inexpensive, nd lrger smple msses cn be used without the risk of explosion becuse the system opertes t tmospheric pressure. Additionlly, the nlyticl frequency is higher nd the volume of wste generted is lower. Anlyticl results The figures of merit for the clibrtion curves for ll nlytes (Al, C, Fe, Mg, Mn nd Zn) obtined using ICP OES re shown in Tble 1. Good liner correltion coefficients were obtined for the curves (R > 0.99). The limit of detection (LOD) nd the limit of quntifiction (LOQ) were clculted s three nd ten times the stndrd devition of ten mesurements of the blnk, divided by the slope of the clibrtion curve, respectively. For ll mesurements, single nlyticl curve ws prepred using stndrd queous solutions, independent of the cid decomposition method employed. Thus, it ws possible to obtin the sme LODs nd LOQs becuse the sme smple msses nd finl volumes of the solutions were used in both methods. The ccurcy of the method ws ssessed through nlyte ddition nd recovery experiments by dding three levels of concentrtion of the inorgnic stndrds to yerb mte smple (E) using both smple decomposition procedures. All the smples were spiked prior to the Tble 1. Figures of merit for the determintion of Al, C, Fe, Mg, Mn nd Zn concentrtions by ICP OES in yerb mte smples Anlyte Liner rnge / (mg L -1 ) s / (L mg -1 ) R b LOD c / (mg L -1 ) LOD c / (mg kg -1 ) LOQ d / (mg kg -1 ) Al C Fe Mg Mn Zn s: sensitivity of the clibrtion curve; b R: correltion coefficient; c LOD: limit of detection; d LOQ: limit of quntifiction.

5 Vol. 27, No. 4, 2016 Pereir et l. 689 decomposition experiments. The results re shown in Tble S4. The recoveries rnged from 81 to 113%, showing the ccurcy of the methods. The precision, expressed s the reltive stndrd devition (RSD, %) ws verified, nd the vlues were lower thn 13.8% nd 12.0% for mesurements using the reflux system nd microwve decomposition, respectively. To obtin informtion bout the concentrtions of Al, C, Fe, Mg, Mn nd Zn in the yerb mte smples from ICP OES nlysis, the smples were decomposed using two procedures: cid decomposition using the reflux system nd microwve digestion. The concentrtions obtined re shown in Tble 2. According to these results nd the ppliction of the t-test t the 95% confidence level, no significnt differences were found between the concentrtions of ny nlyte using the two decomposition procedures. Although some concentrtions of the nlytes listed in Tble 2 showed high RSD (> 10.0%), the precision ws generlly better using the reflux system, with RSD verge of 2.7 nd 5.3% for procedures 1 nd 2, respectively. Considering tht pproximtely 50 g of yerb is used to prepre the mte nd tht in mny plces n dult person drinks this beverge two times dy, pckge of one kilo of yerb mte my be exhusted over period of 10 dys. Tking into ccount this informtion nd the results of Tble 2, it is possible to estimte the ingestion of inorgnic constituents due to the consumption of yerb mte. It is importnt to highlight tht these vlues re the totl contents of the elements nd not the concentrtion tht is extrcted when the yerb is used to prepre hot beverge, s is usully done in the South of Brzil. It is lso importnt to note tht the Brzilin legisltion only estblishes mximum vlues for As, Pb nd Cd in yerb mte (nd other vegetbles used for infusion drinks), but it is possible to find some recommended vlues for other inorgnic elements As shown in Tble 2, high concentrtions of C ( mg kg -1 ), Mg ( mg kg -1 ) nd Mn ( mg kg -1 ) were observed. For C, the vlues found re in ccordnce with those estblished s sfe (20 25 g for 10 dys consumption). For Mg nd Mn, however, the vlues re higher thn those recommended (2.6 g in 10 dys for Mg nd 0.02 to 0.05 g in 10 dys for Mn). The concentrtions of Fe in the nlyzed smples rnged from 130 to 360 mg kg -1. This indictes tht greter mount is consumed thn is recommended, i.e., 100 to 200 mg in 10 dys. 20,22,25 For Zn, the concentrtions rnged from 41 to 72 mg kg -1. Recommended vlues for zinc ingestion re between 100 nd 150 mg every 10 dys. 20,22,26 For Al, the concentrtions found in the nlyzed smples vried between 125 nd 370 mg kg -1, while the recommended intke of Al is 30 to 140 mg every 10 dys. 21,27 The higher vlues of Al, C, Mn nd Mg concentrtions found in smples of yerb mte re in greement with the results reported by Wróbel et l. 9 nd Mrcelo et l. 28 The elements tht did not present dequte ccurcy nd precision or sensitivity by ICP OES nlysis were then investigted by other techniques of tomic spectrometry. Tble 2. Anlyticl results for the yerb mte smples obtined using ICP OES nd the different tretments (n = 3) Concentrtion, x ± SD / (mg kg -1, %) Anlyte Reflux system Smple A Smple B Smple C Smple D Smple E Al ± ± ± ± ± 6.4 C ± ± ± ± ± Fe ± ± ± ± ± 6.8 Mg ± ± ± ± ± 16.8 Mn ± ± ± ± ± 15.6 Zn 42.9 ± ± ± ± ± 0.4 Microwve digestion Smple A Smple B Smple C Smple D Smple E Al ± ± ± ± ± 6.2 C ± ± ± ± ± Fe ± ± ± ± ± 2.7 Mg ± ± ± ± ± 22.1 Mn ± ± ± ± ± 14.2 Zn 41.0 ± ± ± ± ± 0.7 SD: stndrd devition.

6 690 Acid Decomposition of Yerb Mte (Ilex prguriensis) Using Reflux System J. Brz. Chem. Soc. New nlytes were quntified (N, K, Cu, Cd, Cr nd Pb), nd vilbility studies were performed. To quntify the concentrtions of other nlytes, such s N, K, Cu, Cd, Cr nd Pb, in the seprted yerb mte fter the consumption of mte nd in the wter (fter extrction t 80 ºC), five yerb mte smples (F, G, H, I nd J) were nlyzed using tomic spectrometric techniques. The concentrtions of C, Fe, Mg nd Zn were lso determined. The decomposition of the seprted yerb mte ws performed using procedure 1 (cid decomposition in n open system with cold finger), s described in the Experimentl section. For determintion of nlytes in the wter obtined fter infusion, the smples were directly nlyzed (without smple pre-tretment). The nlytes N nd K, C, Cu, Fe, Mg nd Zn, nd Cd, Cr, Pb were determined by FAES; FAAS nd GF AAS, respectively. The figures of merit obtined re presented in Tble 3. The clibrtion curves were constructed for ech nlyte using inorgnic stndrds diluted in n cid medium. As seen in Tble 3, the clibrtion curves presented good linerity (R > 0.99) for ll nlytes investigted. The LOD vlues obtined for Mg nd Zn re better thn those obtined by other more sensitive techniques such s ICP OES. 28 The ccurcy of the cid decomposition in n open system with cold finger for the determintion of the C, Cu, Fe, K, Mg, N, Zn, Cr, Cd nd Pb contents by tomic spectrometric techniques ws evluted vi ddition nd recovery experiments by spiking two smples of yerb mte (F nd I) with queous stndrds t different levels of concentrtions. The results re presented in Tble S5. The recovery vlues obtined rnged from 87 to 110% for ll nlytes, confirming the ccurcy of the decomposition method nd lso showing tht this method cn be successfully used for the smple preprtion of yerb mte, followed by nlysis using different tomic spectrometric techniques. In generl, the RSD vlues were lower thn 11.0%. The obtined concentrtions of C, Cd, Cr, Cu, Fe, K, Mg, N, Pb nd Zn in five commercil yerb mte smples (F, G, H, I nd J) re shown in Tble 4. In the five smples nlyzed, it ws found tht the highest concentrtions were obtined for the nlytes C, K nd Mg, in greement with the results from Heinrichs nd Mlvolt 6 nd Wróbel et l. 9 The N concentrtion in ll smples verged 0.16 mg g -1. For dults, the recommended dily intke is mximum of 2 g of N (20 g in 10 dys), nd the control of its concentrtion is importnt to void problems relted to high blood pressure. 28,29 Toxic elements such s Cd, Cr nd Pb were lso determined in ll smples. According to Weln et l. 30 the levels of concentrtion for those elements re normlly very low nd my vry mrkedly mong different types of te. In June 2014, the Sindmte (The Union of Industry Mte in the Stte of Rio Grnde do Sul) relesed news bout the presence of toxic metls such s Pb nd Cd in yerb mte in concentrtions bove those permitted by legisltion (0.6 mg kg -1 of Pb nd 0.4 mg kg -1 of Cd). The mount bove the estblished limit ws determined directly in the dry yerb mte. However, it is importnt to know if the metls present in the herb re extrcted fter the infusion process when the yerb mte comes into contct with hot Tble 3. Figures of merit for the determintion of C, Cd, Cr, Cu, Fe, K, Mg, N, Pb nd Zn by tomic spectrometric techniques FAES e Liner rnge / (mg L -1 ) s / (L mg -1 ) R b LOD c / (mg kg -1 ) LOQ d / (mg kg -1 ) N K FAAS f C Cu Fe Mg Zn GF AAS g Cd h i Cr h i Pb h i s: sensitivity of the clibrtion curve; b R: liner correltion coefficient; c LOD: limit of detection; d LOQ: limit of quntifiction; e FAES: flme tomic emission spectrometry; f FAAS: flme tomic bsorption spectrometry; g GF AAS: grphite furnce tomic bsorption spectrometry; h unit: (µg L -1 ); i unit: (L µg -1 ).

7 Vol. 27, No. 4, 2016 Pereir et l. 691 Tble 4. Concentrtions of nlytes in yerb mte smples obtined using tomic spectrometric techniques (n = 3) Anlyte FAES c / (mg g -1 ) Concentrtion x ± SD,b Smple F G H I J N 0.15 ± 0.01 (6.7) 0.17 ± 0.01 (5.9) 0.15 ± 0.01 (6.7) 0.17 ± 0.01 (5.9) 0.15 ± 0.01 (6.7) K ± 0.86 (6.2) ± 0.14 (0.9) ± 0.17 (1.2) ± 0.33 (2.6) ± 0.12 (0.9) FAAS d / (mg g -1 ) C ± 0.24 (1.7) ± 1.21 (5.2) ± 0.91 (3.9) ± 0.12 (0.6) ± 0.49 (2.3) Cu ± (9.1) ± (9.1) ± (8.3) ± (7.1) ± (8.3) Fe 0.52 ± 0.03 (5.7) 0.41 ± 0.04 (9.7) 0.30 ± 0.01 (3.3) 0.41 ± 0.01 (2.4) 0.21 ± 0.01 (4.8) Mg 8.72 ± 0.87 (9.9) 6.21 ± 0.04 (0.6) 7.42 ± 0.47 (6.3) 7.11 ± 0.11 (1.5) 7.19 ± 0.39 (5.4) Zn 0.18 ± 0.01 (5.6) ± (1.9) 0.10 ± 0.01 (10.0) ± (2.3) ± (2.4) GF AAS e / (mg kg -1 ) Cd 0.66 ± 0.01 (1.5) 0.41 ± 0.02 (4.9) 0.45 ± 0.01 (2.2) ± (1.2) 0.35 ± 0.01 (2.8) Cr 1.48 ± 0.02 (1.3) 1.63 ± 0.04 (2.4) 1.64 ± 0.08 (4.9) 1.11 ± 0.01 (0.9) 1.56 ± 0.05 (3.2) Pb 1.23 ± 0.15 (12.1) 0.66 ± 0.05 (7.5) < LOQ f 1.08 ± 0.01 (0.9) 1.71 ± 0.04 (2.4) SD: stndrd devition; b in prenthesis: reltive stndrd devition; c FAES: flme tomic emission spectrometry; d FAAS: flme tomic bsorption spectrometry; e GF AAS: grphite furnce tomic bsorption spectrometry; f LOQ: limit of quntifiction. wter. Hence in this work, the concentrtions of nlytes tht remin in the yerb mte brley nd lso in the wter fter the infusion process were determined. For the first study, the yerb mte smples were prepred s described in the Experimentl section (procedure 3), nd the results obtined re shown in Tble 5. Among the ten nlytes in the smples investigted, only K, Mg nd N showed significnt decrese in the concentrtion in the brley mte, with verge reductions of 74, 46 nd 31% of the initil concentrtion (Tble 4), respectively. This indictes tht these nlytes re highly vilble nd re leched in hot wter. Lrge vritions in the concentrtions of other nlytes were not observed. As the brley mte ws nlyzed without ny grinding tretment, it cn be concluded tht the vritions in the results cn be esily ffected by the homogeneity of the smples. Thus, this procedure does not seem to be the most pproprite to evlute the vilbility of the nlytes in the yerb mte smples. Subsequently, n nlysis of the wter fter the infusion process (procedure 4) ws crried out, nd the obtined results re shown in Tble 6. The concentrtions of Cr, Fe nd Pb were lower thn the limit of detection of the method for ll the investigted smples. Additionlly, trnsferences of C, Cd, Cu, K, Mg, N, nd Zn were detected, nd lower vilbilities were observed for C nd Cd. We concluded tht this method ws more effective to ssess the trnsfer of the nlytes from the yerb mte to the wter. Although the presence of toxic elements ws detected, their concentrtions were lower thn those estblished by legisltion nd do not present helth risks for the popultion tht consumes the beverge. Thus, we cn conclude tht to hve more effective qulity control, performing nlysis on the yerb mte lone is Tble 5. Concentrtions of K, Mg nd N, nd percentge not trnsferred in yerb mte smples (n = 3) Smple Concentrtion / (mg g -1 ) K Mg N PNT / % Concentrtion / (mg g -1 ) PNT / % Concentrtion / (mg g -1 ) F 3.69 ± ± ± G 4.26 ± ± ± H 2.49 ± ± ± I 1.93 ± ± ± J 5.48 ± ± ± Percentge not trnsferred. PNT / %

8 692 Acid Decomposition of Yerb Mte (Ilex prguriensis) Using Reflux System J. Brz. Chem. Soc. Tble 6. Concentrtions of C, Cd, Cu, K, Mg, N nd Zn nd percentge trnsferred in wter fter infusion process (n = 3) Smple F G H I J Concentrtion PT / % Concentrtion PT / % Concentrtion PT / % Concentrtion PT / % Concentrtion PT / % Anlyte C / (mg g -1 ) 0.96 ± ± ± ± ± Cd / (µg g -1 ) ± ± ± < LOD b < LOD b Cu / (mg g -1 ) ± ± ± ± ± K / (mg g -1 ) 7.44 ± ± ± ± ± Mg / (mg g -1 ) 3.47± ± ± ± ± N / (mg g -1 ) ± ± ± ± ± Zn / (mg g -1 ) ± ± ± ± ± PT: percentge trnsferred; b LOD: limit of detection. not enough; it is necessry to nlyze the wter fter the infusion process. Conclusions The procedure for smple preprtion bsed on cid decomposition using reflux system for the determintion of Al, C, Fe, Mg, Mn nd Zn in yerb mte by ICP OES showed good results tht re comprble with the microwve-ssisted digestion system. The procedure is simple, nd only HNO 3 nd H 2 O 2 re used for smple digestion. Due to its simplicity nd the cpbility of ICP OES to nlyze multiple elements, the reflux system shows good potentil for ppliction to routine nlysis (qulity control) of this type of smple, nd it cn lso be utilized for the determintion of voltile elements, such Pb nd Cd. The discrepncies observed in the concentrtions in ll yerb mte smples nlyzed re explined by differences in plnt physiology s well s contributions of the externl environment during cultivtion, i.e., the soil type nd climte conditions. 31 To evlute the vilbility of nlytes in yerb mte smples, the more effective procedure is to nlyze the wter fter the infusion process. Supplementry Informtion Supplementry informtion is vilble free of chrge t s PDF file. Acknowledgements The uthors grtefully cknowledge the Conselho Ncionl de Desenvolvimento Científico e Tecnológico (CNPq) nd Coordenção de Aperfeiçomento de Pessol de Nível Superior (CAPES) (Editl Csdinho Process No /2011-4) for their finncil support nd scholrships. References 1. Esmelindro, M. C.; Tonizzo, G.; Wczuk, A.; Driv, C.; Oliveir, D.; Ciênc. Tecnol. Aliment. 2002, 22, Crneiro, C.; Reissmnn, C. B.; Mrques, R.; Cerne 2006, 12, Filip, R.; Lotito, S. B.; Ferrro, G.; Frg, C. G.; Nutr. Res. 2000, 20, Filip, R.; López, P. G.; Giberti, G.; Coussio, J.; Ferrro, G.; Fitoterpi 2001, 72, Sindimte-RS, ccessed in November Heinrichs, R.; Mlvolt, E.; Cienc. Rurl 2001, 31, Mitr, S.; Smple Preprtion Techniques in Anlyticl Chemistry; John Wiley & Sons: New Jersey, Oliveir, E.; J. Brz. Chem. Soc. 2003, 14, Wróbel, K.; Wróbel, K.; Urbin, E. M. C.; Biol. Trce Elem. Res. 2000, 78, Ttsch, F. R. P.; Gonçlves, V. C.; Meurer, E. J.; Scienti Agrri 2010, 11, Krug, F. J.; Métodos de Prepro de Amostrs: Fundmentos sobre Prepro de Amostrs Orgânics e Inorgânics pr Análise Elementr, 1 st ed.; CENA/USP: Pircicb, Korn, M. G. A.; Bo Morte, E. S.; Sntos, D. C. M. B.; Cstro, J. T.; Brbos, J. T. P.; Teixeir, A. P.; Fernndes, A. P.; Welz, B.; Sntos, W. P. C.; Sntos, E. B. G. N.; Korn, M.; Appl. Spectrosc. Rev. 2008, 43, Nookbkew, S.; Rngkdilok, N.; Styvivd, J.; J. Agric. Food Chem. 2006, 54, Crducci, C. N.; Dbs, P. C.; Muse, J. O.; J. AOAC Int. 2000, 83, Ferreir, S. L. C.; Silv, L. O. B.; Sntn, F. A.; Silv Jr., M. M.; Mtos, G. D.; Sntos, W. N. L.; Microchem. J. 2013, 106, Oreste, E. Q.; Jesus, A.; Oliveir, R. M.; Silv, M. M.; Vieir, M. A.; Ribeiro, A. S.; Microchem. J. 2013, 109, Oreste, E. Q.; Oliveir, R. M.; Nunes, A. M.; Vieir, M. A.; Ribeiro, A. S.; Anl. Methods 2013, 5, 1590.

9 Vol. 27, No. 4, 2016 Pereir et l Pinheiro, A. C. A.; Lisbo, M. T.; Ribeiro, A. S.; Nunes, A. M.; Ymski, A.; Quim. Nov 2014, 37, Mlik, J.; Szkov, J.; Drbek, O.; Blik, J.; Kokosk, L.; Food Chem. 2008, 111, Sidelles, A. P. F.; Kirchner, R. M.; Sntos, N. R. Z.; Flores, E. M. M.; Brtz, F. R.; Aliment. Nutr. 2010, 21, World Helth Orgniztion (WHO); Trce Elements in Humn Nutrition nd Helth; WHO: Genev, Azevedo, F. A.; Chsin, A. M.; Metis: Gerencimento d Toxicidde; Atheneu: São Pulo, Food Ingredients Brsil, Dossiê: Os Mineris n Alimentção, No. 4, ccessed in November Environmentl Control Agency of São Pulo Stte (CETESB); Fich de Informção Toxicológic (FIT), cetesb.sp.gov.br/servicos/informcoes-toxicologics/ ccessed in November Hung, X.; Mutt. Res. 2003, 533, Lukski, H. C.; Int. J. Sport Nutr. 1995, 5, 74S. 27. Agency for Toxic Substnces nd Disese Registry (ATSDR), ccessed in November Mrcelo, M. C. A.; Mrtins, C. A.; Pozebon, D.; Dressler, V.; Ferrão, M. F.; Microchem. J. 2014, 117, World Helth Orgniztion (WHO); Guideline: Sodium Intke for Adults nd Children; WHO: Genev, Weln, M.; Szymczych-Mdej, A.; Pohl, P.; Food Res. Int. 2013, 53, Kr, D.; Food Chem. 2009, 114, 347. Submitted: September 11, 2015 Published online: November 18, 2015 FAPERGS/CAPES hs sponsored the publiction of this rticle. FAPESP hs sponsored the publiction of this rticle.