In situ evaluation of DGT techniques for measurement of trace. metals in estuarine waters: a comparison of four binding layers

Transcription

1 Electronic Supplementry Mteril (ESI) for Environmentl Science: Processes & Impcts. This journl is The Royl Society of Chemistry 2015 Supplementry Informtion for: In situ evlution of DGT techniques for mesurement of trce metls in esturine wters: comprison of four binding lyers with open nd restricted diffusive lyers Amir Houshng Shiv, Willim W. Bennett, Dvid T. Welsh nd Peter R. Tesdle* Environmentl Futures Reserch Institute, Griffith University, Gold Cost cmpus, QLD 4215, Austrli *Corresponding Author: Ph: Fx:

2 Contents Experimentl 1. Uptke nd elution efficiencies for PAMPAA binding lyer 2. Assessment of Metsorb cid wsh for oxynion mesurements Results 1. Uptke nd elution efficiencies for PAMPAA binding lyer 2. Assessment of Metsorb cid wsh for oxynion mesurements Tbles Tble S1: Chrcteristics of the different types of DGT diffusive nd binding lyers used in the study Tble S2: Uptke nd elution efficiencies of trce metls for PAMPAA binding lyer Tble S3: Men concentrtions of metls mesured by DGT-MBL, DGT-Chelex, DGT- Metsorb nd DGT-PAMPAA using open diffusive lyer (ODL) nd restricted diffusive lyer (RDL) t Runwy By Mrin Tble S4: Men concentrtions of metls mesured by DGT-MBL, DGT-Chelex, DGT- Metsorb nd DGT-PAMPAA using open diffusive lyer (ODL) nd restricted diffusive lyer (RDL) t The Spit 2

3 Figures Figure S1: The effect of cid wsh on DGT-Metsorb mesurements Figure S2: Plots of 1/M (ng -1 ) versus diffusive lyer thickness (Δg, cm) for DGT-MBL deployments t The Spit Figure S3: Rtios of DGT mesurements for trce metls using different binding lyers with restricted (RDL) nd open (ODL) diffusive lyers t The Spit References 3

4 Experimentl 1. Uptke nd elution efficiencies for PAMPAA binding lyer Uptke efficiencies for Al, Cd, Co, Cu, Mn, Ni, Pb nd Zn were mesured by immersing five PAMPAA gel discs in 5 ml of 100 µg L -1 of either Al solution (prepred in 0.01 mol L -1 NNO 3 t ph 8.30) or mixed nlyte solution (prepred in 0.01 mol L -1 NNO 3 t ph 6.00). The solutions were gently shken for 24 h nd the gels were removed for nlysis. To determine the mss of nlytes remining in the solution, subsmples were tken nd nlysed by ICP-MS fter cidifiction (2% HNO 3 ). The totl mss of dsorbed metls nd consequently uptke efficiencies were clculted by difference. To mesure elution efficiencies, the PAMPAA binding lyers were immersed in 5 ml of 2 mol L -1 HNO 3 for 24 h nd the mss of eluted metls determined. The elution efficiency ws clculted s the frction of the totl metl tht ws eluted for ech element 1, Assessment of Metsorb cid wsh for oxynion mesurements In ddition to the set of DGT-Metsorb deployed for oxynion mesurements, second set of DGT-Metsorb ws deployed in triplicte for mesurement of Al lone; these Metsorb binding lyers were cid wshed in mol L -1 HNO 3 prior to elution to increse the elution efficiency of Al 1. This cid wsh process, however, my ffect the concentrtion of other oxynions on the binding lyer, s they my be prtilly eluted. In this study, we hve compred the concentrtion of Al nd oxynions (As, Sb nd V) mesured by DGT-Metsorb which were either cid wshed or not prior to elution, in order to determine the effect of the cid wsh on Metsorb mesurements of oxynions. 4

5 Results 1. Uptke nd elution efficiencies for PAMPAA binding lyer The determined uptke nd elution efficiencies of trce metls for PAMPAA binding lyer re provided in Tble S2. The uptke efficiencies for Al, Cu nd Pb were 89.7 ± 2%, 75.5 ± 1% nd ± 1% (n= 5), respectively. For ll other ctions, the results were between 34-55% (n= 5). PAMPAA elution efficiencies (using 2 mol L -1 HNO 3 ) for ll ctions were between 81 nd 97% (n= 5). No elution efficiencies for oxynions were mesured becuse ll the uptke efficiencies were <26%. This discrepncy is not surprising s most of the functionl groups of the PAMPAA gel (negtively chrged crylic cid) re likely to chelte ctions preferentilly (see Section 3.3 in the text). 2. Assessment of Metsorb cid wsh for oxynion mesurements Metsorb binding lyers deployed in sewter must be plced in deionised wter prior to elution with NOH 2, 3. Rinsing with wter removes slts (C nd Mg) ssocited with the binding lyer nd prevents the formtion of hydroxides nd/or crbontes tht cn interfere with elution. For Al mesurements, it hs been reported tht rinsing the Metsorb binding lyers in diluted HNO 3 prior to wshing with wter increses the elution efficiencies 1. However, lthough Al nd oxynions re ccumulted simultneously on the Metsorb binding gel, no study hs so fr investigted the effect of cid wsh procedure on DGT- Metsorb mesurements of oxynions. Figure S1 illustrtes the results of comprison of Al, V, As nd Sb concentrtions determined using DGT-Metsorb t the study smpling sites, where the binding lyers were nlysed either with or without the cid wsh procedure prior to elution with NOH. The concentrtion of Al mesured without the cid wsh ws 5

6 significntly (p <0.05) underestimted by 58% nd 50% t Runwy By Mrin nd The Spit, respectively; whilst no significnt differences (p >0.05) were observed for V, As nd Sb concentrtions t either site between cid wshed nd unwshed Metsorb binding lyers. It is therefore recommended tht the cid pre-wsh be used routinely for DGT-Metsorb nlyses, which obvites the need to use seprte sets of DGT-Metsorb for oxynion nd Al mesurements, nd enbles these to be mesured simultneously using single set of DGT- Metsorb smplers. 6

7 Tbles Tble S1: Chrcteristics of the different types of DGT diffusive nd binding lyers used in the study. DGT lyers Monomer type Crosslinker type Pore size (nm) Trget nlyte Mechnism of binding Diffusive lyer open diffusive lyer (ODL) restricted diffusive lyer (RDL) crylmide crylmide grose derivtive biscrylmide > 5 < 1 Chelex-100 resin incorported into polycrylmide grose derivtive _ ctionic metls complextion with free ions Binding lyer polycrylmidepolycrylic cid copolymer (PAMPAA) derived from polycrylmide grose derivtive _ ctionic metls complextion with free ions Metsorb resin incorported into polycrylmide grose derivtive _ oxynionic metls dsorption of free ions Chelex-Metsorb mixed binding lyer (MBL) incorported into polycrylmide grose derivtive _ ctionic nd oxynionic metls complextion nd dsorption 7

8 Tble S2. Uptke nd elution efficiencies of trce metls for PAMPAA binding lyer. Dt re mens the stndrd devition of the men (n = 5). Metl Uptke efficiency Elution efficiency Al Mn Co Ni Cu Zn Cd Pb ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

9 Tble S3: Men concentrtions of metls mesured by DGT-MBL, DGT-Chelex, DGT- Metsorb nd DGT-PAMPAA using open diffusive lyer (ODL) nd restricted diffusive lyer (RDL) t Runwy By Mrin. DGT-ODL DGT-RDL Metl MBL Chelex Metsorb PAMPAA MBL Chelex Metsorb PAMPAA Mn Co Ni Cu Zn Cd Pb Al V As Sb

10 Tble S4: Men concentrtions of metls mesured by DGT-MBL, DGT-Chelex, DGT- Metsorb nd DGT-PAMPAA using open diffusive lyer (ODL) nd restricted diffusive lyer (RDL) t The Spit. DGT-ODL DGT-RDL Metl MBL Chelex Metsorb PAMPAA MBL Chelex Metsorb PAMPAA Mn Co Ni Cu Zn Cd Pb Al V As Sb

11 Figures Figure S1. The effect of cid wsh on DGT-Metsorb mesurements. Solid columns represent concentrtions mesured using cid wshed binding lyers nd htched columns represent concentrtions mesured using unwshed binding lyer. Dt re men vlues nd error brs indicte the stndrd devition of the men. Columns with different letter lbels indicte significntly different (<0.05) results for DGT mesurements. b b 11

12 Figure S2. Plots of 1/M (ng -1 ) versus diffusive lyer thickness (Δg, cm) for DGT-MBL deployments t The Spit. 12

13 Figure S3. Rtios of DGT mesurements for trce metls using different binding lyers (MBL= mixed binding lyer, Ch= Chelex, PAM = PAMPAA, Ms= Metsorb) with restricted (RDL) nd open (ODL) diffusive lyers t The Spit. 13

14 References 1. J. G. Pnther, W. W. Bennett, P. R. Tesdle, D. T. Welsh nd H. Zho, Environmentl Science & Technology, 2012, 46, J. G. Pnther, P. R. Tesdle, W. W. Bennett, D. T. Welsh nd H. Zho, Environmentl Science & Technology, 2010, 44, W. W. Bennett, P. R. Tesdle, J. G. Pnther, D. T. Welsh nd D. F. Jolley, Anlyticl Chemistry, 2010, 82,