untitled Highly se bromate with UV‐ Hamed Moh Department of Ch *Corresponding a Tel.: +966.5.0451 ARTICLE INFO Received: 28 Janu Received in revis Accepted: 20 Feb Online: 30 June 2 KEYWORDS Triiodide ion Ozonated water Preconcentration Sample treatmen Complex ion asso Dispersive liquid 1. Introductio As a resu water, import (DBPs) have (ClO3−) are fo disinfectant, a with hypochlo ozonation of w of several by (OBr−), hypob bromate (BrO by the Intern primary caus Environmenta Organization ( (MCL) of 10 µg guideline val analytical tech different sam techniques an for the determ The literature bromate in va concentration, detection (IC‐C combined with (HPLC/ICP‐MS pressure ioniz ensitive p ions in w ‐Vis spect hammed Al‐ hemistry, University uthor at: Departme 2320; fax: +966.2.5 ORMATION uary 2012 ed form: 19 Febru ruary 2012 012 n nt ociate ‐liquid microextra on ult of the proc tant inorganic o been reporte rmed when ch and the presen orite has also be water containin y‐products suc bromous acid O3−) [2]. Bromat ational Agency sative agent o al Protection A (WHO) establis g/L for bromat lue is provisi hniques availab mples. Thus, s nd predominant mination of ultra e provides a w ariety of samp , e.g., ion ch CD) [4], high pe h inductively c S) [5], ion ch zation mass sp Eu ISSN 2153‐ Europ J procedure water by d trophotom ‐Saidi y College in Makkah ent of Chemistry, U 5566401. E‐mail ad ary 2012 action cesses used to oxyhalide disin d. Chlorite (C hlorine dioxide nce of chlorate een described [ ng bromide ind ch as bromine (HOBr), bromo te has been cla y of Research f cancer, and Agency (EPA) hed a maximum e in drinking w ional because le for monitorin ensitive and tly routine met a trace and trac wide range of m ples from sub‐µ romatography erformance liqu oupled plasma hromatography pectrometry (IC uropean Journal Europe 2249 (Print) / IS DOI:10.5155 pean Jo Journal home e for the d dispersive metry h, Umm Al Qura Un University College in ddress: alsaidihm@ ABSTRACT In the present w of bromate ion (TPP+ I−) as an produce triiodi bromate ions, a optimum cond associate were respectively, w method offers (LOQ) of the br constant of th respectively. T chromatograph method did not the application drinking water o disinfect drin nfection by‐prod ClO2−) and chl (ClO2) is used e in waters tre [1]. Additionally duces the form e, hypobromite oform (CHBr3), assified in Grou Cancer (IARC) therefore, th and World H m contaminant water [3]. In fact of limitation ng bromate lev selective analy thods are nece ce levels of brom methods to an µg/L level to m with conduc uid chromatogr mass spectrom with atmosp C/API‐MS) and of Chemistry 3 ( ean Journal of Ch SSN 2153‐2257 5/eurjchem.3.2. ournal o epage: www.e determina e liquid‐liq iversity, Makkah, 2 n Makkah, Umm Al @yahoo.com (H.M. A work, a novel, si ns in water. The n ion pairing rea ide ion (I3−). Th and TPP+ was ex itions, Beer’s‐La e obeyed in the with a relative s 0.003 and 0.01 romate ion, resp he developed io The proposed m hic, spectrofluor t need a special n of DLLME and treated by ozon nking ducts orate d as a eated y, the ation e ion , and up 2B as a e US Health level t, this ns in els in ytical ssary mate. alyze mg/L tivity raphy metry heric with indu [6], thes by E (ISO chro wide dete dete by p solu inter Alth selec this hand com prop rout oper spec spec dete thes and their A selec at e (2) (2012) 202‐2 hemistry (Online)  2012 202‐207.590 of Chem eurjchem.com ation of ul quid micr 21955, Saudi Arabia Qura University, M Al‐Saidi). imple, and green method is base agent and a sou he complex ion xtracted by disp ambert law and range of 0.01‐ tandard deviati 12 µg/mL lower pectively. Moreo on associate we method was fre rimetric and s treatment of sa was successfull ne and tap water uctively couple and GC‐MS wi e techniques, ( EPA and Inter O) for monitori omatography w ely used for ection limit of ection limit in th preconcentratio tion. On the rferences of ch ough many imp ctivity and sens method time d, the main oth mplexity and the per operation. T tine analysis. Th rate, highly sen ctrophotometry ctrophotometri ermination in d e methods are trace concentr r low sensitivity Although, there ctivity and sen xtremely low 207 2 EURJCHEM mistry m ltra‐trace roextracti a Makkah, 21955, Sau n procedure is p ed upon using t urce of iodide io n associate form persive liquid‐liq d Ringbom’s plo ‐0.5 and 0.02‐0 on in the range r limits of dete ver, the chemica ere found to b ee from most i spectrophotome ample for elimin ly used to the a . ed plasma mas th negative ch (IC‐CD) is docu rnational Orga ing bromate co with both cond the direct de f 7 and 10 µg he range of 0.5‐ on step or evapo other hand, hloride, sulphat provements we sitivity of meth ‐consuming an her disadvanta e need of some Therefore, such he developmen nsitive and relia y is still of g c methods has different sample not suitable fo rations of brom y and selectivity e are many kin sitivity, the dir concentrations amounts ion comb udi Arabia. presented for th etraphenylphos ons that react w med between I3 quid microextrac ot of the colore .2 µg/mL of Br e of 2.1 ± 1.3% ction (LOD) and al composition a be [TPP+ I3−] a interferences pr tric methods. nating the interfe analysis of brom ss spectrometr emical ionizati umented as an o anization for S oncentration [4 ductivity and U etermination o g/L, respective ‐1.0 µg/L can on orating of brom IC‐CD suffers te, and some m ere carried out hod, such impro nd highly cost. ges of this tech e degree of exp h techniques are nt of low cost m able for routin great concern s been reporte es [2,9‐13]. How or monitoring mate in drinking y. nds of instrum rect determinat s is still proble s of ined e determination phonium iodide with bromate to −, equivalent to ction. Under the ed complex ion rO3− at 365 nm, %. The proposed d quantification and the stability nd 4.43 × 105, resent in many The developed erences prior to mate ion in both ry (IC/ICP‐MS) ion [7]. Among official method Standardization 4]. In fact, ion UV detectors is of bromate at ely [8]. Lower nly be achieved mate‐containing s from severe metal ions [1,9]. to increase the ovements made . On the other hnique are the ertise for their e not suited for method, easy to e analysis, e.g., . A series of ed for bromate wever, most of the ultra trace g water due to ents with high tion of analytes ematic. In this n e o o e n , d n y , y d o h ) g d n n s t r d g e . e e r e r r o , f e f e o h s s Al‐Saidi / European Journal of Chemistry 3 (2) (2012) 202‐207 203 case, the preconcentration step is necessary. Liquid‐liquid extraction (LLE) is widely used as a pre‐treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of toxic organic solvents, which makes LLE tedious, and environmentally unfriendly. The search for alternatives to the conventional LLE using negligible volumes of extractant and in minimum number of steps has driven the development of some new miniaturized methodologies like single‐drop microextraction (SDME), hollow fiber liquid‐phase microextraction (HF‐LPME), cloud point extraction (CPE), and dispersive liquid‐liquid microextraction (DLLME) [14]. DLLME developed by Assadi et al. in 2006 has been widely applied to the analysis of heavy metals, pesticide residues and so on [15‐ 18] due to its excellent analytical performance compared to other microextraction techniques. It is well known that, the ion pairing reagents tetraphenylphosphonium halide (TPP+ X−) can form stable complex ion associates with several of oxoanions in organic media. One of these complexes, formed between tetraphenyl phosphonium bromide (TPP+ Br−) and halochromate (CrO3Cl−), has been employed for developing a simple, convenient, and low cost spectrofluorimetric and spectrophotometric methods for the determination and speciation of chromium (III, VI) in water samples [19,20]. Therefore, the aim of the present study was to develop a novel environmentally friendly procedure for the determination of bromate ions in water using the ion pairing reagent tetraphenylphosphonium iodide (TPP+ I−), followed by DLLME of the formed ion associate into organic phase and subsequent UV‐vis spectrophotometric detection. 2. Experimental 2.1. Apparatus The UV‐visible (190 ‐ 1100 nm) spectra were recorded on a Perkin‐Elmer (model Lambda 25, USA) spectrophotometer using a quartz micro cell (45 mm high, internal width 4 mm and path length 10 mm) with 800 μL internal capacity. A digital micropipette (Volac) and an Orion pH meter (model EA 940) were used for the preparation of more diluted bromate ion solutions and pH measurements, respectively. Deionized water was obtained from Milli‐Q Plus system (Millipore, Bedford, MA, USA) and used for preparation of solutions. 2.2. Reagents All chemicals and solvents used were analytical reagent grade and used without further purification. Stock solutions (1000 µg/mL) of BrO3−, Cr(VI), Cr(III), As(V), MnO4−, NO2−, ClO3−, IO3− and H2O2 were prepared from the BDH chemicals (Poole, England) KBrO3, K2CrO4, Cr(NO3)3, NaAsO3, KMnO4, NaNO2, KClO3, KIO3 and H2O2, (30%, w/v) in water (100.0 mL), respectively. Solutions of other metal ions were prepared from their nitrate or chloride salts in deionized water. A stock solution (0.1%, w/v) of the reagent TPP+I−(Merck, Darmstadt, Germany) was prepared by dissolving the required weight in ethanol (3.0 mL) and the solution was then completed to the mark with deionized water. 2.3. Recommended procedure for bromate determination Various concentrations (0.01‐0.50 μg/mL) of bromate ion were put into centrifugal tubes. Next, 0.3 mL of 5 mol/L HCl and 0.2 mL of 0.1 %TPP+I− were added, and the volume was filled up to 1 mL with deionized water. After that, 0.5 mL of methanol (as a disperser solvent) containing 70 µL of chloroform (as extraction solvent) was rapidly injected using a 2.0 mL syringe. A cloudy solution was rapidly produced due to the formation of fine droplets of extraction solvent, and the complex ion associate formed was extracted into these fine droplets. The mixture was gently shaken and then centrifuged at 3000 rpm for 2 min. After this process, the dispersed fine droplets of CHCl3 were sedimented at the bottom of conical test tube, and the remained organic layer was then removed using a Hamilton syringe and diluted to 500 µL by methanol. The absorbance of diluted organic phase was measured at 365 ± 3 nm. 2.4. Determination of bromate in tap and bottled water Tap water collected from the laboratories of Chemistry Department, King Abdul Aziz University, Jeddah city, KSA, and bottled water, commercially available in Saudi market, were filtered through 0.45µm cellulose membrane filter prior to analysis and stored in LDPE sample bottles (250 mL). Aliquots of 1.0 mL of each sample were adjusted to the required acidity and analyzed following the recommended procedure of bromate determination. 3. Results and discussion Preliminary study has shown that, on mixing bromate ion with the ion pairing reagent TPP+I− (Figure 1) in aqueous HCl solution, yellow‐colored species was developed. The electronic absorption spectrum of the mixture in water showed two well‐ defined peaks at 290 and 352 nm against reagent blank (Figure 2b) confirming the formation of triiodide ion (I3−) [21]. In the absence of BrO3‐, the absorption spectrum of the reagent TPP+I− in aqueous HCl solution showed no absorption band in the range of 300‐500 nm (Figure 2a). Similar trend was also observed on shaking the reagent or bromate ion individually with chloroform. However, bathochromic shift of the above mentioned two peaks has occurred at 295 and 365 nm (Figure 2c) after shaking the aqueous HCl solution containing the reagent TPP+I− and bromate ion with chloroform confirming the formation of complex ion associate. The composition of the produced ion associate was determined by Job's continuous variation and molar ratio methods at 365 nm [22]. The results revealed that, the ratio of I3−, equivalent to bromate ions, to TPP+I− was 1:1 molar ration. Thus, the most probable composition of the extracted species is [TPP+ I3−]. The stability constant of the produced complex ion associate calculated from the Job's plot from the ratio of the true absorbance (A) to the extrapolated (Aextp) absorbance was found equal to 4.43 × 105 [22]. P I - Figure 1. The chemical structure of reagent TPP+I‐. Based on these results in chloroform and the data reported earlier for the complex ion associate of the ion pairing reagent TPP+ Br− with chloro chromate (CrO3Cl−) in HCl media [20], and the reaction of bromate with iodide ion in acidic medium [10], the overall reaction of bromate with TPP+I− in HCl (1.5 mol/L) is most likely proceeded as follows: TPP+I−  TPP+ + I− (1) BrO3‐ + 9I− + 6H+  3I3− + Br‐ + 3H2O (2) TPP+ + I3−  [TPP+I3−] (3) 204 Figure 2. Electro in water (B), a chloroform (C). On the oth 365 nm of the was found to of the title rea bromate ions. DLLME techni will be focused extractive spe bromate ion in 3.1. Optimiza 3.1.1. Influenc Because th halides (TPP+ associates in s DLLME efficie (2.0 mol/L).Th using HCl. Th influence of ch explained in concentration results shown signal (absorb concentration Figure 3. Influen the ion associate 3.1.2. Effect of The type important fa solvents used than water, hi and low solub detection, the onic spectra of the and the develope her hand, the va e complex ion a be 2.5×105 L/m agent for the spe . With taking i ique compared d on the use of ctrophotometr n water. tion of DLLME ce of acidity he ion pairing r X−) have stron strong acidic me ency was tested he maximum an his behavior i hloride ion on t detail in [23 (0.5‐2.0 mol in Figure 3 ind bance) was ach of 1.5 mol/L w nce of HCl concent in organic phase. f the extraction of extraction ctor for effic in normal DLL igh efficiency f bility in water ere is one mor A reagent TPP+I− in ed complex ion alue of the mola associate devel mol.cm suggesti ectrophotomet nto account th d to normal LL this technique ic method for t reagents tetrap ng trend for th edia [19,20], th d in H2SO4, HCl, nd stable absor is most likely he oxidative pr 3]. Therefore, l/L) was criti dicate that, the m hieved above 1 was employed in tration (0.5 ‐ 2.0 m n and disperse solvents used cient extractio LME should ha for the extractio . Moreover, In re requirement Al‐Saidi / Europea n water (A), triiodi associate [TPP+I ar absorptivity loped in chloro ing the possibl ric determinati he characteristi E, the further w to develop sens the determinati phenylphospho he formation o e effect of acidi , HNO3 or CH3C rbance was achi y attributed to roperties of bro the effect of ically studied. maximum analy .0 mol/L. Thus n further work. mol/L) on absorba er solvent type d in DLLME i on. The extra ave a higher de on of target an the case of U t, namely mini an Journal of Che de ion I3−] in (ε) at oform e use ion of ics of work sitive ion of nium of ion ity on COOH ieved o the omate f HCl The ytical s, HCl ance of is an action ensity nalyte UV‐vis mum extra pair mus with dich carb g/m g/m disp both acet of c extra acet of an inve the CH2C blan Mor stab were in fu Figur condi acidit w/v) 3.1.3 T expe 0.50 5 in volu appr betw optim effec diffe 70 proc reac then prob solv asso 3.1.4 T TPP the emistry 3 (2) (20 action of the b s are extracted t be taken into h low dielectric hloromethane (d bon tetrachlori mL), and chlorof mL) was tested persive solvent h water and onitrile, ethano chloroform, d action solvents one as dispers nalytical respon estigated. The r extraction reco Cl2 in all used nk response in C eover, mixture le two‐phase s e selected as ex urther work. re 4. Effect of the itions: water samp ty (HCl), 1.5 mol/ ; BrO3‐, 0.2 μg/mL; 3. Effect of the To examine the erimental cond 0 mL methanol ndicates that th ume of chlor roximately con ween 70 and 9 mum volume o ct of the dispe erent volumes o µL of chlorofo cedure. The ob ched to its max n gradually dec bably due to in ent in water an ociate. 4. Effect of the The variation o + I− concentrati reagent (0.1% 012) 202‐207 lank test [24]. , the dielectric o account. Thus constant, and h dielectric const de (dielectric form (dielectric d. On the othe is limited to so extraction so ol and acetone . dichloromethan s with methan ive solvents w nse as well as s results present overy decreased disperser solv CCl4 was higher e of chloroform ystem. Therefo xtraction and di e extraction solve ple, 1.00 mL; disp /L; the ion pairin ; dilution solvent ( extraction and e effect of the e ditions were fix plus different v he absorbance roform to 70 nstant by furth 0 µL. Therefor of extraction sol erser solvent v of methanol (in orm were sub tained results ximum value at creased by furt creasing of the nd thus lower e concentration of the absorban ion was evalua , w/v) from 0 On the other h constant of ext s, a series of or higher density t tant, 9.1, densit constant, 2.2, c constant, 4.81 er hand, the olvents that are olvents such In this study, al e, carbon tet nol, acetonitrile ere performed, ignal‐to‐noise r ted in Figure 4 d in the order vents. On the o r than that in CH m and methano ore, chloroform isperser solven ent on the analytic perser solvent (me ng reagent (TPP+·I methanol), ≈ 500 µ d disperser solv extraction solve xed and includ volumes of chlo increased by 0 µL and th her increasing re, 70 μL was s lvent. In order volume, solutio the range of 0. bjected to the showed that, t t 0.5 mL of the ther increasing e dissolution of extraction effici of ion‐pair rea ce as a function ated by increas .1 to 0.5 mL a hand, when ion traction solvent rganic solvents than water, e.g. ty, 1.33 g/mL), density, 1.59 1, density, 1.48 selection of a e miscible with as methanol, ll combinations trachloride as e, ethanol and , and the value ratio were then 4 revealed that, CHCl3 ≈ CCl4 > other hand, the HCl3 (Figure 4). l formed more m and methanol ts, respectively cal signal. DLLME ethanol), 0.50 mL; I−), 0.2 mL (0.1% µL. vent volume ent volume, the ded the use of oroform. Figure increasing the hen remained of its volume selected as the to examine the ons containing 2 ‐ 0.8 mL) and same DLLME the absorbance e methanol and g of its volume, f the extraction iency of the ion agent n of the reagent ing volumes of at the optimum n t s . , 9 8 a h , s s d e n , > e . e l y E ; % e f e e d e e e g d E e d , n n t f Table 1. Toleran Interfering spec As3+, Ni2+, Bi3+, Li+ Fe3+, Fe2+, Hg2+, Pb NO2−, H2O2 , ClO2− MnO4−, Cr6+ IO3− experimental 0.1% (w/v) of A large excess the absorbanc the reagent b recommended volume of 0.2 used in furthe Figure 5. Influen analytical signal. solvent (methano (TPP+I−), 0.2 mL ( 3.1.5. Effect of Extraction extraction pro the time betw extractant and time was exam constant expe extraction ac formation of achieved quic DLLME. In fac quickly into t surface area b after the form time‐consumin centrifugation fine droplets o 3.2. Selectivity To test t influence of oxyhalide disi on the determ bromate was tolerance lim species causin in Table 1, m tolerated even interfering ser and MnO4−. Ho by the additi manganese(VI ce limits of interfe cies +, Na+, K+, Ca2+, Mg2 b2+, Mn2+, Co2+, Cr3 , ClO3−, OBr− conditions. Th f TPP+ I− was su s of the reagen ce possibly owi lank. Amounts d value gave 2 mL, correspo r experiments. nce of the extract Conditions for ext ol), 0.50 mL; acidit (0.1% w/v); BrO3‐, f the extraction n time is one of ocedures. In DL ween injection d starting to c mined in the ra erimental cond ccomplished in cloudy solutio ckly, which wa ct that, the com the extraction s between extra mation of cloudy ng step, that n of sample solu of extraction sol y the selectivity various ions infection by‐pr mination of a investigated un it was defined ng less than a ±5 most metal cat n at a high co riously with bro owever, the inte ion of few dr II) to mangane Al‐Saidi / ring species in the 2+, Al3+, Ag+, CO32−, S +, Cl−, F−, Br− he results show ufficient to extra nt concentration ing to the incre of the reagen incomplete ex nding to its m tion solvent (chlo traction: water sam ty (HCl), 1.5 mol/L 0.2 μg/mL. n time the most key fa LLME, extractio mixture of dis entrifuge. The ange of less tha ditions. The r n a very sho on and the equ as one of the m mplex ion associ solvent due to ction solvent a y solution. In th t required ab ution performe lvent dispersed y of the prop s involving c oducts, e.g., ClO concentration nder the optim d as the conc 5% relative erro tions, and inor oncentration le omate determin erference of Mn rops 0.1%, m/ ese(II). After th / European Journ e analysis of 20.0 µg SO42−, NO32−, CN− wed that, 0.2 m act up to 0.5 μg n tends to decr eased absorban nts smaller than xtraction. Thus maximum value, roform) volume o mple, 1.00 mL; disp L; the ion pairing re actors in the mo n time is defin sperser solvent effect of extra an 1 to 15 min results showed ort time after uilibrium state main advantag iate formed dif the infinitely and aqueous p his method, the bout 2 min, ed for collectin d in aqueous ph posed method, common inorg O2−, ClO3−, and of 0.20 µg/m mum conditions entration of a or. As demonstr rganic anions evel. The only nation are IO3−, nO4− was elimin /v NaN3 to re his modification al of Chemistry 3 g/Lofbromate ion. mL of g/mL. rease nce of n the , the , was on the perser eagent ost of ed as t and action with d the r the e was ges of ffuses large phase e only was g the hase. , the ganic OBr− mL of . The added rated were ions , Cr6+, nated educe n, the toler limit 3.3. U brom was (7.94 A = 1 with good abso selec The the R on th were sam µg/m com meth fluor is su dete ClO2 meth sam main The adva cons of a envi time Figur addit 0.3 (D 3.4. T anal mar labo 3 (2) (2012) 202‐ rance of the in t (98±2%). Figure of meri Under the opti mate ion concen linear in th 4×10−8 to 3. 97 1.912 C (µg/mL h correlation co d linearity in th orption spectra cted concentrat effective conce Ringbom’s plot he IUPAC [22], e 0.003 and 0. ple. The relativ mL of bromate mparison of the hod made w rimetric, and s ummarized in T ection limit [11 2, Cd2+, Br‐ and hod was also c e reaction (the n characteristic novel DLLME antages in c sumption of ext lower amount ironmentally fr es; (c) better sen re 6. UV‐visible a tion of various con D) and, 0.5 µg/mL Application The accuracy o lysis of bromat ket of Saudi A oratories of Che ‐207 Interfering 1000:1 100:1 70:1 5:1 0.5:1 nterfering ions its imized experim ntration vs. abs he concentrat ×10−6 mol/L) w L) + 0.0037 oefficient of 0. he mentioned co a of [TPP+I−3] in tions of broma entration range t was in the ran the values of L .012 µg/mL, re ve standard de ions was in the e main analytic with many of pectrophotome Table 2. Some o 1], and serious Cl‐ [2,10,23,25, compared to co formation of io cs of both proc E procedure h omparison to traction solven of organic wast riendly; (b) sho nsitivity. absorption spectru ncentrations of bro (E). of the developed te ions in bott Arabia, and Ta mistry Departm g to analyte ratio was improved mental conditio sorbance of [TP ion range 0.0 with the regress 997 (n = 8), w oncentration ra n chloroform up ate ion are show of bromate ion nge of 0.02‐0.2 LOD and LOQ o espectively, usi eviation at conc e range of 2.1± cal features of f the previou etric methods of these metho s interferences ,26]. Moreover, onventional LLE on associate of cedures are giv has the follow o normal LLE nt and consequ te, thus making orter extractio um of [TPP+I−3] in omate ion: 0.05 (A d method was tled water, ava ap water, colle ment, King Abdu 205 d to acceptable ons, the plot of PP+ I3−] in CHCl3 01‐0.5 µg/mL sion equation: (5) which indicates ange. UV‐visible pon addition of wn in Figure 6. ns evaluated by 2 µg/mL. Based of bromate ions ing 1.00 mL of centration 0.25 1.3% (n = 6). A f the proposed usly published [2,10,23,25,26] d exhibits high of NO2‐, ClO3‐, , the developed E based on the [TPP+ I3−]). The ven in Table 3. wing significant E: (a) lower ent production g the procedure n and analysis chloroform upon A); 0.1 (B), 0.2 (C), checked by the ailable in local ected from the ul Aziz e f 3 L s e f . y d s f 5 A d d ] h , d e e . t r n e s n , e l e 206 Al‐Saidi / European Journal of Chemistry 3 (2) (2012) 202‐207 Table 2. Figure of merits of the developed and some of the reported fluorimetric and spectrophotometric methods for bromate determination in water. Method, Ref. Reagent Linear Rang, (µg/mL) LOD, (µg/mL) Remarks FI ‐ Spectrophotometry, [23] Prochlorperazine (PCP) 0.01 ‐ 0.13 0.002 Very sensitivity, the interferences of NO2−, ClO2−, ClO−. Direct ‐ spectrophotometry, [2] KI 0.05 ‐ 5.00 0.014 Low sensitivity, the interferences of MoO42−, WO42−, NO2− FI ‐ Fluorimetry, [26] Sulphite ‐ steroid hydrocortisone 0.045 ‐ 63.000 0.010 Low sensitivity, the interferences of Br−, Cl− Kinetic ‐ Spectrophotometry, [10] KI 0.05 ‐ 1.50 0.01 Low sensitivity, the interferences of MoO42−, WO42−, NO2− FI ‐ Spectrophotometry, [25] Chlorpromazine 0.025 ‐ 0.750 0.006 Moderate sensitivity, the interferences of NO2−, ClO2, hypochlorite. SIA ‐ Spectrophotometry, [11] 5‐bromo(PADAD) ‐ SCN‐ 0.18 ‐ 3.00 0.15 Very low sensitivity, the interferences of ClO3−, IO3−, Cr6+ Spectrophotometry, [Present work] TPP+I− 0.01 ‐ 0.50 0.003 The method is very sensitivity, and free from the interferences of inorganic oxyhalide disinfection by‐products e.g. ClO2−, ClO3− and OBr− , the only interferences are IO3−, Cr6+, MnO4− Table 3. Comparison of conventional LLE, and DLLME procedures for determination of bromate ions in water. Parameters Procedure LLE a DLLME λmax , nm 365 365 Regression equation A = 0.001+ 0.186 × C A = 0.0037 + 1.912 × C Linear range, µg/mL 0.05 ‐ 1.2 0.01 ‐ 0.5 LOD, µg/mL 0.017 0.003 Volume of organic phase used for absorbance measurement, µL 4000 500 a Conditionsof LLE:HCl and reagent concentrations = 1.5 mol/L, 0.008% (w/v), respectively; volume of extraction solvent = shaking twice with chloroform (2x2 mL) ; shaking time = 3 min. Table 4. Analysis of bromate ions by the developed spectrofluorimetric method in water samples (mean ± standard deviation, n = 5). Sample Bromate ion, Added (µg/mL) Bromate ion, Found (µg/mL) Recovery, % Bottled water __ 0.035 ND 0.036 ± 0.0012 __ 102.1 ± 1.2 Ozonated bottles water (1) __ 0.050 0.015 ± 0.0018 0.062 ± 0.0013 __ 95.5 ± 2.3 Ozonated bottles water (2) __ 0.05 0.015 ± 0.0018 0.062 ± 0.0013 __ 95 ± 2.3 Tap water __ 0.040 ND 0.039 ± 0.00167 __ 97.5 ± 4.3 ND = Not detected. University, Jeddah City, KSA. The results are summarized in Table 4, the percentage recoveries of the method were always higher than 95% confirming the accuracy of the developed method and its independence from the matrix interference. 4. Conclusions This work describes a new sensitive and selective spectrophotometric procedure for the determination of bromate ions in water samples without pre‐treatment step prior to the application of DLLME. The proposed method has the following advantages: high selectivity, good reproducibility, stable absorbance up to 4 h. On the other hand, the developed method is free from the inferences of SO42‐, Cl‐, NO2‐ and ClO2‐ that can be considered common interferences in many chromatographic, spectrofluorimetric and spectrophotometric methods. The method provides LOD much lower than the maximum allowable level (10.0 µg/L) of bromate ion in drinking water recommended by the US Environmental Protection Agency and World Health Organization (WHO). 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