Determination of anions at trace levels in power plant water samples by ion chromatography with electrolytic eluent generation and suppression

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1 Journl of Chromtogrphy A, 956 (2002) locte/ chrom Determintion of nions t trce levels in power plnt wter smples by ion chromtogrphy with electrolytic eluent genertion nd suppression * Zhongqing Lu, Yn Liu, Victor Brreto, Chris Pohl, Nebojs Avdlovic, Robert Joyce, Beverly Newton Reserch nd Development, Dionex Corportion, 1228 Titn Wy, Sunnyvle, CA , USA Abstrct An ion chromtogrphic method ws developed for the determintion of nine inorgnic nd orgnic cid nions t sub- to low-mg/ l levels in power plnt wter smples. In this method, smples were injected using lrge-volume direct injection technique, the nlyte nions were seprted on hydroxide-selective nion-exchnge column using high-purity hydroxide eluents generted by n on-line electrolytic eluent genertor nd detected using the suppressed conductivity detection method. The method performnce ws evluted by nlyzing synthetic wter smples contining dditives encountered in the power plnt wter smples nd four wter smples from fossil fuel power plnt. The reltive stndrd devitions of retention times of nlyte ions seprted on the hydroxide-selective nion-exchnge column were less thn 0.4%. The recoveries of nlyte ions spiked into the synthetic wter smples t concentrtions of mg/ l were in the rnge of %. The method detection limits for nlyte ions in deionized wter were , , 0.019, 0.057, , 0.023, 0.067, 0.037, nd mg/ l for fluoride, cette, formte, chloride, nitrite, sulfte, bromide, nitrte, nd phosphte, respectively Elsevier Science B.V. All rights reserved. Keywords: Wter nlysis; Inorgnic nions; Orgnic cids 1. Introduction turbine bldes, susceptible to stress corrosion crcking. The minimiztion of the concentrtions of It is essentil for power plnts to monitor the corrosive ions in the boiler feed wter nd in the presence nd movement of ionic impurities in vri- effluent from the condenste polisher reduces the ous wter strems used in the power genertion corrosion dmge to vrious system components. process including feed wter, boiler wter, stem, The mesurement of ionic impurities throughout the nd cooling wter [1 3]. The presence of corrosive power genertion process cn provide vluble innionic species such s chloride nd sulfte in the formtion regrding the source of contmintion, the process wter strems even t low-mg/ l levels cn likely rtes of contminnt build-up, nd probble mke the stinless steel components of power rtes of corrosion, s well s extremely useful nd plnt, such s stem genertors, boiler tubes, nd timely dt during the strt-up nd shut-down of power plnts. The relible nd ccurte determintion of nions in power plnt wter smples t sub- *Corresponding uthor. Tel.: ; fx: to low-mg/l levels is chllenging nlyticl prob- E-mil ddress: yn liu@dionex.com (Y. Liu). ] lem. Over the pst 20 yers, ion chromtogrphy / 02/ $ see front mtter 2002 Elsevier Science B.V. All rights reserved. PII: S (02)

2 130 Z. Lu et l. / J. Chromtogr. A 956 (2002) (IC) hs become n indispensble technique for using high-purity potssium hydroxide eluents generddressing this problem becuse IC offers the unique ted by n on-line electrolytic eluent genertor nd cpbility to seprte nd identify individul ionic detected using the suppressed conductivity detection species t sub- to low-mg/l levels [4 10]. method. The performnce of the new method ws There hve been severl recent dvnces in IC tht evluted by nlyzing synthetic wter smples hve improved the determintion of nions t trce contining dditives encountered in the power plnt levels. First, new nd improved hydroxide-selective wter smples s well s wter smples from fossil nion-exchnge seprtion columns offer unique fuel power plnt. selectivity to seprte inorgnic nd orgnic nions of interest for trget pplictions [11 15]. Dilute solutions of lkli hydroxides re used s eluents for 2. Experimentl hydroxide-selective seprtion columns. Hydroxide eluents re idel for both isocrtic nd grdient 2.1. Instrumenttion elution in IC becuse they re converted to wter in the suppressor nd the hydroxide concentrtion hs A Dionex DX 600 IC system (Dionex, Sunnyvle, little effect on bckground conductnce. Thus, IC CA, USA) consisting of GS50 grdient pump, n using hydroxide-selective columns cn offer signifi- EG40 eluent genertor module, n LC25 chromtogcnt dvntges in the determintion of nions of rphy module, nd n ED40 conductivity detector interest t trce levels. Secondly, n electrolytic ws used in the experiments. A PekNet 6.2 chromdevice cpble of on-line electrolytic genertion of togrphy worksttion ws used for instrument conhigh-purity crbonte-free potssium hydroxide trol, dt collection, nd processing. An EGC-KOH eluents ws introduced [10,16]. The preprtion of crtridge ws instlled in the EG40 eluent genertor crbonte-free lkli hydroxide eluents by conven- nd used to generte potssium hydroxide eluents tionl mens is difficult becuse crbonte my be on-line. To remove trce mounts of dissolved introduced s n impurity from the source chemicl crbon dioxide nd nionic contminnts in the or by dsorption of crbon dioxide from the ir. The deionized wter, Dionex ATC-1 column (24 mm3 presence of crbonte in hydroxide eluents often 9 mm) pcked with high-cpcity nion-exchnge compromises the performnce of n IC method. The resin in the hydroxide form ws instlled between crbonte contmintion cn cuse undesirble chro- the pump outlet nd the inlet of the EGC-KOH mtogrphic bseline drift during the hydroxide crtridge. The LC25 chromtogrphy module mingrdient, nd possibly irreproducible retention times tined the temperture of the gurd nd seprtor of trget nlytes. The on-line electrolytic potssium columns nd the conductivity cell t 30 8C. A smple hydroxide eluent genertor elimintes these problems loop with volume of 1000 ml ws mde from nd provides n idel source of eluents for use with length of in. I.D. polyether ether ketone hydroxide-selective nion-exchnge columns. The (PEEK) tubing nd its volume ws verified by third recent dvnce in IC ws the development of mesuring the mss difference between the smple new nd improved electrolytic suppressors [17,18]. loop filled with deionized wter nd the empty loop These new electrolytic suppressors improve the (1 in cm). The seprtions of trget nlyte determintion of nions t trce levels becuse they nions were performed on IonPc AS15-5 mm (150 offer severl dvntges such s ese of use, low mm33 mm I.D.) nd AG15-5 mm (30 mm33 mm bseline noise, nd fst equilibrtion. I.D.) columns. An Anion Atls Electrolytic Suppres- In this pper, we report new IC method tht sor (AAESTM) operted in the recycle mode ws utilizes the recent dvnces in IC for the determi- used s the suppressor. Detils of the IC system ntion of trget nions t sub- to low-mg/l levels in operting conditions re presented in Tble 1. power plnt wter smples. In this method, the wter smple is injected using the lrge-loop direct in Regents, smples, nd procedures jection technique, the nlyte nions re seprted on new hydroxide-selective nion-exchnge column A stock stndrd solution contining 20 mg/ l

3 Z. Lu et l. / J. Chromtogr. A 956 (2002) Tble 1 IC system operting conditions Columns: IonPc AS15, 5 mm (15033 mm) IonPc AG15, 5 mm (3033 mm) Trp columns: IonPc ATC-1 Trp, 4 mm Eluent: KOH (source: EG40) Temperture: 30 8C Pump progrm: Time Flow A Vlve EG40 Conc. (min) (ml/min) (%) (mm) Injection volume: Detection: Suppressor: Suppressor current setting: Lod Lod Inject Inject Inject Lod Lod ml Suppressed conductivity Anion Atls electrolytic suppressor, recycle mode 50 ma fluoride, 30 mg/ l chloride, 100 mg/ l nitrite, 100 in polyethylene continers tht hd been thoroughly mg/ l bromide, 100 mg/ l nitrte, 150 mg/ l phos- clened nd presoked in deionized wter for t lest phte, nd 150 mg/l sulfte, vilble from Dionex 24 h. (P/ N 56933), ws used in this study. Sodium cette Hydrzine (99.8%) nd ethnolmine (.99.5%) (99.99%) nd sodium formte (99.99%), obtined were obtined from Aldrich; mmonium hydroxide from Aldrich (Milwukee, WI, USA), were used to (trce metl grde, 20 22%) ws obtined from prepre stock stndrd solution contining 100 Fisher Scientific (Pittsburgh, PA, USA); boric cid mg/l cette nd 100 mg/l formte. The two stock (99.8%) ws obtined from BDH (Poole, UK); nd stndrd solutions were used to prepre composite sodium crbonte (ACS grde) ws obtined from stndrd solution contining 0.40 mg/ l fluoride, 3.0 EM Science (Gibbstown, NJ, USA). These chemicls mg/l cette, 3.0 mg/l formte, 0.60 mg/l chloride, were used s dditives to prepre synthetic mtrices 2.0 mg/ l nitrite, 3.0 mg/ l sulfte, 2.0 mg/ l bromide, without further purifiction. To simulte the wter 2.0 mg/ l nitrte, nd 3.0 mg/ l phosphte. The smple mtrices encountered in the power plnt clibrtion stndrd solutions were prepred dily by opertion, four synthetic wter smples were prediluting the composite stndrd solution to the pred using deionized wter nd dditives including expected concentrtion rnge for the trget nions hydrzine, ethnolmine, mmonium hydroxide, using deionized wter. boric cid, nd sodium crbonte. Tble 2 summ- Deionized wter with specific resistnce of 18.2 rizes the concentrtions of dditives in the four MV cm from Milli-Q Plus deionized wter system synthetic wter smples. The synthetic wter smples (Millipore, Bedford, MA, USA) ws used to prepre were spiked with 0.13 mg/ l fluoride, 1.0 mg/ l ll the solutions. Extreme cution ws tken to cette, 1.0 mg/ l formte, 0.20 mg/ l chloride, 0.67 prevent ny possible contmintion from the en- mg/ l nitrite, 1.0 mg/ l sulfte, 0.67 mg/ l bromide, 1.0 vironment nd the smple hndling when prepring mg/l nitrte, nd 1.0 mg/l phosphte. ll trce-level clibrtion stndrd solutions. All Four power plnt wter smples, including min clibrtion stndrds nd spiked smples were stored stem, condenste pump dischrge, economizer inlet

4 132 Z. Lu et l. / J. Chromtogr. A 956 (2002) Tble 2 cette, formte, chloride, nitrite, sulfte, bromide, Composition of synthetic wter smple mtrices studied nitrte, nd phosphte [19]. For ccurte determi- Component Added concentrtion (mg/ l) ntion of trget nlyte ions t sub- to low-mg/ l Mtrix I Mtrix II Mtrix III Mtrix IV levels, it is criticl to mximize the nlyte response while minimizing the chromtogrphic bseline Hydrzine Ethnolmine noise. To increse the nlyte response, the lrge- Boric cid volume direct inject technique ws used to inject Ammonium ml of smple in this method. Since the IonPc Crbonte AS15-5 mm column hs sufficient ion-exchnge cpcity, no noticeble bnd brodening of nlyte peks ws observed due to the loding of such lrge wter, nd boiler drum wter, were obtined from smple volume. The use of the lrge-volume direct Four Corners Fossil Fuel Power Plnt (Fruitlnd, injection technique elimintes the need for the NM, USA) operted by Arizon Public Services. The smple pre-concentrtion step tht typiclly involves smples were nlyzed directly without ny pretret- the use of concentrtor column nd is more ment. For the boiler drum wter smple, 1000-fold cumbersome nd time-consuming. dilution ws lso performed prior to nlysis in order To minimize the chromtogrphic bseline noise, to quntify the concentrtions of sulfte nd phos- the use of nion Atls electrolytic suppressors ws phte due to the high concentrtions of sulfte nd investigted. The recently developed nion Atls phosphte present in the originl smple. electrolytic suppressors re continuous electro- To perform nlysis of stndrds nd smple lyticlly-regenerted suppressors designed minly for solutions, the stndrd or smple ws loded into the the suppression of crbonte hydrogen crbontesmple loop with 5-ml syringe. The six-port bsed eluents in IC [17,18]. One of the key dvninjection vlve in the LC25 chromtogrphy module tges of the nion Atls electrolytic suppressor is tht ws set up such tht the syringe ws used to pull the it provides very low chromtogrphic bseline noise smple slowly into the 1000-ml smple loop to void (typiclly 1 2 ns/cm) even when it is operted in ny possible contmintion. To ensure tht the the recycle mode. The suppression cpcity of the system ws free of contmintion, the system ws nion Atls suppressor is 25-mN eluent t 1.0 ml/ equilibrted with 40 mm KOH generted by the min. This study determined the mximum concen- EG40 eluent genertor t 0.5 ml/min for t lest 30 trtion of KOH eluents t 0.5 ml/min tht could be min upon system strt-up. The system clenliness suppressed effectively using the nion Atls suppresws verified by nlyzing deionized wter blnk sors. Three nion Atls suppressors were tested. The prior to nlyzing clibrtion stndrds nd smples. results showed tht the nion Atls suppressors were ble to suppress up to 45 mm KOH t 0.5 ml/min. Tble 3 summrizes the typicl bseline noise vlues 3. Results nd discussion Tble Optimiztion of chromtogrphic conditions Typicl bseline noise vlues obtined using KOH eluents nd nion Atls electrolytic suppressors Vrious wter strems used in the power plnt Suppressor Averge bseline noise (ns/ cm) opertion contin inorgnic nions such s chloride unit 30 mm KOH 40 mm KOH 45 mm KOH nd sulfte s well s low-moleculr-mss orgnic nions such s cette nd formte. In this study, the IonPc AS15-5 mm column ws chosen s the seprtion column becuse this newly-developed The flow rte ws 0.50 ml/min. The suppressors were operted column is hydroxide-selective nion-exchnge in recycle mode with n operting current of 50 ma. column designed specificlly for rpid nd efficient Averge pek-to-pek noise mesured in 1-min segments over seprtion of trget nlyte nions including fluoride, 20 min.

5 obtined using the nion Atls electrolytic suppressors nd KOH eluents of 30, 40, nd 45 mm t 0.5 ml/min. When the suppressors were supplied with 50 ma of current nd operted in the recycle mode, the verge pek-to-pek noise mesured in 1-min segments over 20 min rnged from 0.3 to 1.0 ns/cm. Severl fctors were considered when optimizing the hydroxide grdient conditions for the seprtion of trget nlyte ions on the IonPc AS15-5 mm column. First, the mximum concentrtion of the KOH eluent used in the grdient ws limited to 45 mm during the hydroxide grdient so tht the nion Atls electrolytic suppressor could be operted within its effective suppression cpcity. Second, the grdient condition ws optimized to ensure good resolution of trget nlyte ions from borte since the power plnt wter smples might contin boric cid s n dditive. In the optimized grdient seprtion, the concentrtion of the KOH eluent ws mintined t 7 mm for 8 min to llow resolution of wekly retined ions such s fluoride, cette, nd formte. A hydroxide grdient from 7.0 to 40 mm KOH ws then performed using the EG40 eluent genertor to seprte more strongly retined nions including chloride, nitrite, sulfte, bromide, nitrte, nd phosphte. The seprtion ws performed t 30 8C to Z. Lu et l. / J. Chromtogr. A 956 (2002) Fig. 1. A representtive chromtogrm obtined for the smple of 18 MV cm deionized wter spiked with nine trget nions. Pek identifiction nd spike concentrtion: 15fluoride (0.13 mg/l), 25cette (1.0 mg/l), 35formte (1.0 mg/l), 45chloride (0.2 mg/l), 55nitrite (0.67 mg/l), 65crbonte, 75sulfte (1.0 mg/l), 85bromide (0.67 mg/ l), 95nitrte (0.67 mg/ l), nd 105 phosphte (1.0 mg/l) Evlution of method performnce The method performnce ws evluted by nlyz- ing smples prepred from four synthetic wter smple mtrices tht were designed to simulte those encountered in the power plnt opertion. The comensure consistent retention times for the trget position of the four synthetic wter smple mtrices nlytes. is given in Tble 2. Clibrtion curves for trget Fig. 1 shows representtive chromtogrm ob- nions were obtined using stndrds prepred in tined for stndrd solution of nine trget nions; deionized wter. The clibrtion stndrds nd the the nlyte concentrtions in this stndrd rnged linerity of clibrtion curve for ech trget nion re from 0.13 mg/l for fluoride to 1.0 mg/l for phos- listed in Tble 4. The results show tht clibrtion phte. The bseline shift during the hydroxide grdient ws typiclly less thn 60 ns/cm over run time of 30 min. The miniml bseline shift during the grdient ws due to the use of high purity crbonte-free hydroxide eluents generted by the EG40 KOH eluent genertor. Becuse of low bseline noise, chromtogrphic peks of trget nions could be esily quntified. It is very importnt to estblish system blnk in the determintion of nions t trce levels. Fig. 2 shows representtive system blnk chromtogrm obtined for smple of 18 MV cm lbortory-deionized wter. Trce mounts of cette (0.049 mg/ l), formte (0.081 mg/ l), nd chloride (0.25 mg/ l) in the smple originted from the point-of-use deionized wter system were detected. Fig. 2. A representtive chromtogrm obtined for the smple of 18 MV cm deionized wter. Pek identifiction nd concentrtion: 15cette (0.049 mg/l), 25formte (0.081 mg/l), 35chloride (0.25 mg/ l), nd 45crbonte.

6 134 Z. Lu et l. / J. Chromtogr. A 956 (2002) Tble 4 Clibrtion curve dt for trget nions in deionized wter Anlyte Concentrtion of Correltion clibrtion stndrds (mg/ l) 2 coefficient (r ) Fluoride 0.013, 0.040, 0.13, 0.40, Acette 0.10, 0.30, 1.0, 3.0, Formte 0.10, 0.30, 1.0, 3.0, Chloride 0.020, 0.060, 0.20, 0.60, Nitrite 0.067, 0.20, 0.67, 2.0, Sulfte 0.10, 0.30, 1.0, 3.0, Bromide 0.067, 0.20, 0.67, 2.0, Nitrte 0.067, 0.20, 0.67, 2.0, Phosphte 0.10, 0.30, 1.0, 3.0, Fig. 4. A representtive chromtogrm obtined for the smple of Mtrix III spiked with nine trget nions. Pek identifiction nd curves for trget nions hd good linerity; the spike concentrtion: 15fluoride (0.13 mg/l), 25unknown, 35 cette (1.0 mg/l), 45formte (1.0 mg/l), 55borte (unknown), 2 correltion coefficients (r ) of the clibrtion curves 65chloride (0.20 mg/l), 75nitrite (0.67 mg/l), 85crbonte (1.0 were or greter. mg/ l), 95sulfte (1.0 mg/ l), 105bromide (0.67 mg/ l), 115 Figs. 3 nd 4 show the chromtogrms obtined nitrte (0.67 mg/l), 125phosphte (1.0 mg/l). for smple of Mtrix III nd smple of Mtrix III spiked with trget nions t concentrtions rnging termintion of these trget nions. The smple mtrix from 0.13 mg/l for fluoride to 1.0 mg/l for phos- ws lso designed to determine whether the method phte. Mtrix III ws comprised of deionized wter could be pplied to the nlysis of wter smples spiked with 0.1 mg/ l hydrzine, 3.0 mg/ l ethnol- contining incresed mounts of crbonte. The mine, 10 mg/l boric cid, 40 mg/l mmonium nd concentrtion of crbonte in Mtrix III ws mg/ l crbonte. As shown in Fig. 3, n unknown times of the concentrtion of sulfte. Although nionic species eluted between fluoride nd cette, sulfte eluted on the shoulder of the crbonte pek, nd borte originting from the boric cid dded to the sulfte pek could be quntified esily using this the smple mtrix eluted between formte nd method becuse of low chromtogrphic bseline chloride. Since borte nd the unknown nionic noise yielded by the nion Atls electrolytic suppresspecies in Mtrix III were well seprted from the sor. trget nions, they did not interfere with the de- Tble 5 summrizes the retention time reproducibility dt for nine trget nions seprted on the IonPc AS15-5 mm column obtined through the replicte nlysis of smples prepred from the four synthetic wter mtrices. The results indicte tht the retention times of trget nions were essentilly independent of the smple mtrices nd the reltive stndrd devitions of retention times for nine consecutive mesurements were less thn 0.4%. The retention time reproducibility dt obtined for trget nions compre well with the results obtined in previous study under similr conditions [10]. Experiments were lso performed to determine the recoveries of nine trget nlyte ions spiked into the Fig. 3. A representtive chromtogrm obtined for the smple of four synthetic wter smple mtrices t concentr- Mtrix III. Pek identifiction nd concentrtion: 15fluoride (0.023 mg/l), 25unknown, 35cette (0.074 mg/l), 45formte tions rnging from 0.13 mg/l for fluoride to 1.0 mg/l (0.30 mg/l), 55borte, 65chloride (0.22 mg/l), 75nitrite (0.18 for sulfte nd phosphte. The recoveries of trget mg/ l), nd 85crbonte. nions were clculted fter the subtrction of the

7 Z. Lu et l. / J. Chromtogr. A 956 (2002) Tble 5 Retention times nd reproducibility dt for trget nlyte nions Anlyte Spiked Averge retention time (min)6rsd (%) concentrtion (mg/ l) Mtrix I Mtrix II Mtrix III Mtrix IV Fluoride Acette Formte Chloride Nitrite Sulfte Bromide Nitrte Phosphte The verge retention time nd reltive stndrd devition (RSD) dt were clculted from nine replicte mesurements (n59). limits obtined using the Atls electrolytic suppres- sor in this study re two to six times lower thn those obtined in previous study [20] under similr conditions. The low method detection limits obtined using this method cn be ttributed primrily to the low bseline noise fforded by the nion Atls electrolytic suppressors Anlysis of wter smples from fossil fuel power plnt The method ws used to nlyze four power plnt wter smples collected from Four Corners Fossil Fuel Power Plnt. The wter smples included min stem, condenste pump dischrge, economizer inlet wter, nd boiler drum wter. Fig. 5 shows the chromtogrm obtined for the min stem wter smple, which did not contin dditives. The results mtrix blnk. The results, presented in Tble 6, show tht the verge recoveries were generlly in the rnge of %. These results suggest tht the method performed well for these smples considering tht the trget nions were dded t concentrtions of 1.0 mg/ l or lower. The method performnce ws lso evluted by determining the method detection limits for nine trget nions in four synthetic smple mtrices. To determine the method detection limits, replicte mesurements (n57) of smple mtrices spiked with nlyte ions t concentrtions rnging from 0.04 mg/ l for fluoride to 0.3 mg/ l for sulfte nd phosphte were mde. The results re summrized in Tble 7. For the four synthetic smple mtrices, the method detection limits for trget nions were generlly lower thn 0.1 mg/ l. For trget nlytes in smples of deionized wter, the method detection Tble 6 Spike recovery dt obtined for trget nlyte nions in different mtrices Anlyte Spiked Averge recovery (%)6RSD (%) concentrtion (mg/ l) Mtrix I Mtrix II Mtrix III Mtrix IV Fluoride Acette Formte Chloride Nitrite Sulfte Bromide Nitrte Phosphte The verge recovery nd reltive stndrd devition (RSD) dt were clculted from nine replicte mesurements (n59).

8 136 Z. Lu et l. / J. Chromtogr. A 956 (2002) Tble 7 Method detection limits obtined for nlyte nions in different mtrices Anlyte Spike Method detection limit (mg/l) concentrtion (mg/ l) Mtrix I Mtrix II Mtrix III Mtrix IV Fluoride Acette Formte Chloride Nitrite Sulfte Bromide Nitrte Phosphte The estimted method detection limits were clculted s the stndrd devition of the men mesured concentrtion (n57) multiplied by (Student s t-vlue t 99% confidence). show tht this smple contined 0.16 mg/ l fluoride, min stem wter smple. The condenste dischrge 1.2 mg/ l cette, 3.2 mg/ l formte, 0.18 mg/ l wter smple lso contined 0.44 mg/ l chloride, 3.6 chloride, 0.81 mg/ l nitrite, 0.30 mg/ l sulfte, nd mg/ l sulfte, nd 0.86 mg/ l phosphte, which were 0.27 mg/ l nitrte. No bromide or phosphte were significntly higher thn the concentrtions of these detected in this smple. Fig. 6 shows the chromto- ions in the min stem wter smple. Fig. 7 shows grm obtined for the condenste dischrge wter the chromtogrm obtined for the economizer inlet smple tht ws comprised of the stem condenste wter smple. This smple ws the condenste wter from the turbine nd did not contin dditives. The before it entered the boiler. Ammoni nd hydrzine condenste dischrge wter smple contined 0.16 were dded to the wter s dditives. The ionic mg/ l fluoride, 1.2 mg/ l cette, 3.9 mg/ l formte, 1.3 composition of this smple ws similr to the mg/ l nitrite, nd 0.15 mg/ l nitrte. These levels were condenste dischrge wter smple, s expected. Fig. similr to the concentrtions of these ions in the Fig. 6. The chromtogrm obtined from the condenste dis- Fig. 5. The chromtogrm obtined for the min stem wter chrge wter smple. Pek identifiction nd concentrtion: 15 smple. Pek identifiction nd concentrtion: 15fluoride (0.16 fluoride (0.16 mg/l), 25cette (1.2 mg/l), 35formte (3.9 mg/l), mg/l), 25cette (1.2 mg/l), 35formte (3.2 mg/l), 45chloride 45chloride (0.44 mg/l), 55nitrite (1.3 mg/l), 65crbonte, 75 (0.18 mg/l), 55nitrite (0.81 mg/l), 65crbonte, 75sulfte (0.30 sulfte (3.6 mg/l), 85unknown, 95nitrte (0.15 mg/l), 105 mg/l), 85unknown, 95nitrte (0.27 mg/l), 105unknown. unknown, nd 115phosphte (0.86 mg/l).

9 Z. Lu et l. / J. Chromtogr. A 956 (2002) significnt mounts of phosphte (1600 mg/ l), sulfte (130 mg/ l), nd chloride (33 mg/ l) in this smple due to the ddition of trisodium phosphte nd sodium hydroxide nd the ssocited ionic impurities. 4. Conclusions The results obtined from nlyzing synthetic nd rel power plnt wter smples suggest tht the new IC method developed in this study cn be pplied to determine trget nions t trce levels in power plnt wter smples. The hydroxide-selective AS15-5 mm column provides rpid nd efficient seprtion of Fig. 7. The chromtogrm obtined for the economizer inlet wter smple. Pek identifiction nd concentrtion: 15fluoride (0.16 trget nlyte nions including fluoride, cette, mg/l), 25cette (1.1 mg/l), 35formte (3.8 mg/l), 45chloride formte, chloride, nitrite, sulfte, bromide, nitrte, (0.42 mg/l), 55nitrite (1.3 mg/l), 65crbonte, 75sulfte (3.2 nd phosphte. The use of the EG40 KOH eluent mg/l), 85unknown, 95nitrte (0.17 mg/l), 105unknown, nd genertor elimintes the problems ssocited with the 115phosphte (0.78 mg/l). preprtion of lkli hydroxide eluents nd provides n idel source of eluents for use with hydroxideselective nion-exchnge columns such s the AS15-8 shows the chromtogrm obtined for boiler drum wter smple. The boiler drum is where the 5 mm column. Method detection limits t the ng/l wter nd stem re seprted for the stem to go to level cn be redily chieved using the lrge loop the turbine. This smple contined trisodium phosbseline noise fforded by the nion Atls elec- direct injection technique becuse of the lower phte nd sodium hydroxide s dditives. There were trolytic suppressor. The new method is potentilly more menble to on-line opertions becuse the nion electrolytic suppressor is operted in the recycle mode. Acknowledgements The uthors cknowledge Johnnie Pete Jr. of Arizon Public Service for providing power plnt wter smples nd other useful informtion. References Fig. 8. The chromtogrm obtined for the boiler drum wter [1] Rtionle for Chemicl Control of Feedwter nd Boiler smple. Pek identifiction nd concentrtion: 15fluoride (1.2 Wter, Vol. 1, Electric Power Reserch Institute, Plo Alto, mg/l), 25cette (3.1 mg/l), 35formte (4.0 mg/l), 45chloride Jnury 1984, EPRI Report NP (33 mg/l), 55nitrite (1.3 mg/l), 65crbonte, 75sulfte (130 [2] Monitoring Cycle Wter Chemistry in Fossil Plnts, Vol. 3, mg/l), 85unknown, 95nitrte (0.19 mg/ l), nd 105phosphte Electric Power Reserch Institute, Plo Alto, October 1991, (1600 mg/l). EPRI Report GS7556.

10 138 Z. Lu et l. / J. Chromtogr. A 956 (2002) [3] PWR Secondry Wter Chemistry Guideline, Electric Power [13] P. Jckson, C. Weigert, C. Pohl, C. Sini, J. Chromtogr. A Reserch Institute, Plo Alto, My 1993, EPRI Report TR- 884 (2000) [14] P. Jckson, S. Gokhle, T. Streib, J. Rohrer, C. Pohl, J. [4] L. Blconi, R. Pscli, F. Sigon, Anl. Chim. Act 179 Chromtogr. A 888 (2000) 151. (1986) 419. [15] E. Kiser, J. Rohrer, D. Jensen, J. Chromtogr. A 920 (2001) [5] C. Hschke, LC GC 8 (1990) [6] S. Hrvey, J. Chromtogr. 546 (1991) 209. [16] Y. Liu, N. Avdlovic, C. Pohl, R. Mtt, H. Dhillon, R. Kiser, [7] D. Bostic, G. Burns, S. Hrvey, J. Chromtogr. 602 (1992) Am. Lb. November (1998) 48C [17] Y. Liu, V. Brreto, Z. Lu, N. Avdlovic, presented t the [8] M. Toofn, J. Stillin, C. Pohl, P. Jckson, J. Chromtogr. A Pittsburgh Conference 2001, New Orlens, Mrch, 2001, 761 (1997) 163. pper No [9] E. Kiser, J. Riviello, M. Rey, J. Sttler, S. Heberling, J. [18] Eluent Suppressors for Ion Chromtogrphy, Dionex, Sunny- Chromtogr. A 739 (1996) 71. vle, CA, 2001, Product Informtion Bulletin. [10] Y. Liu, E. Kiser, N. Avdlovic, Microchem. J. 62 (1999) [19] IonPc AS-15 Anion-Exchnge Column, Dionex, Sunny vle, CA, 2001, Product Informtion Bulletin. [11] R. Rocklin, C. Pohl, J. Schibler, J. Chromtogr. 411 (1987) [20] Improved Determintion of Trce Anions in High Purity 107. Wters By High-Volume Direct Injection with the EG40, [12] C. Pohl, J. Stillin, P. Jckson, J. Chromtogr. A 789 (1997) Dionex, Sunnyvle, CA, 2001, Appliction Updte