Validacija metode za analizo Pb(II) z uporabo SPE senzorja

diplomsko delo univerzitetnega študijskega programa I. stopnje

David Majer (Author), Matjaž Finšgar (Mentor), Barbara Petovar (Co-mentor)

Abstract

Težke kovine so prisotne vsepovsod okoli nas in predstavljajo nevarnost živalim in ljudem. Ena izmed metod za določevanje težkih kovin, ki se je uporabljala v zadnjih desetletjih, je polarografija, ki uporablja živo-srebrno elektrodo. Zaradi toksičnih lastnosti živega srebra je prišlo do razvoja metod, ki bi nadomestile živo-srebrno elektrodo. Namen diplomskega dela je delna validacija metode za analizo Pb(II) z uporabo senzorja SPE (angl. screen-printed electrode), ki lahko predstavlja dober nadomestek za živo-srebrno elektrodo. SPE so senzorji, ki imajo na isto površino keramike ali plastike natisnjeno trielektrodno konfiguracijo (delovno, referenčno in pomožno elektrodo). V sklopu validacijskega postopka smo preverjali mejo zaznavnosti, mejo določljivosti, linearnost, točnost in natančnost ter vpliv interferenc. Reverzibilnost elektrodne reakcije SPE-senzorja smo najprej preverili s ciklično voltametrijo (CV), nato smo elektroanalizno metodo izvajali z (angl. square-wave) anodno striping voltametrijo (SWASV). Kot delovno elektrodo smo uporabili elektrodo iz ogljika na senzorju SPE ali modificirano ogljikovo elektrodo z antimonovo plastjo (SbFSPE). Kot medij za tvorbo elektrode smo v slednjem primeru uporabili 0,01 M HCl in 0,5 mg/L Sb(III). Delno validacijo metode smo izvedli z uporabo obeh elektrod. Meja zaznavnosti in meja določljivosti sta bili 1,5 µg/L in 3,0 µg/L za SbFSPE ter 0,5 µg/L in 1,5 µg/L za SPE. Linearnost metode je v koncentracijskem območju med 24,4 µg/L in 319,1 µg/L za SbFSPE in med 69,8 µg/L in 368,4 µg/L za SPE. Točnost metode smo preverjali z določevanjem koncentracije z metodo večkratnega standardnega dodatka pri koncentraciji svinca 169,1 µg/L, natančnost metode pa smo določili z izračunom relativnega standardnega odmika (RSD). Pri zaporednem izvajanju analiz na različnih senzorjih smo ugotovili, da sta točnost in natančnost signifikantno boljša z uporabo SbFSPE kot SPE, kadar senzor uporabimo prvič. Točnost in natančnost se z nadaljnjo uporabo SbFSPE slabšata, medtem ko se točnost SPE izboljša že pri drugi uporabi. Pri zaporedni uporabi istega senzorja smo ugotovili, da je točnost po petih zaporednih uporabah boljša v primeru SPE kot SbFSPE. Študij vpliva interferenc na metodo je pokazal, da se je pri enakih koncentracijah Cd(II) in Pb(II) signal za Pb(II) povečal, medtem ko se je pri masnem koncentracijskem razmerju Pb(II) in Cd(II), 1 : 10, vrh za Pb(II) zmanjšal. Pri 100-krat večji koncentraciji Cd(II) v primerjavi s Pb(II) je prišlo do prekrivanja vrhov, tako vrha za svinec ni bilo mogoče določiti. Zraven Cd(II) so na signal za Pb(II) imeli signifikanten vpliv tudi Hg(II), Bi(III), Cu(II) in Sn(II), medtem ko v prisotnosti Zn(II), As(III), Na(I), Ca(II), Mg(II), K(I), Fe(III) in NO3- ionov ni prišlo do večjih sprememb.

Keywords

validacija;svinec;antimon;določevanje težkih kovin;diplomske naloge;

Data

Language:	Slovenian
Year of publishing:	2018
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[D. Majer]
UDC:	543.55:546.817(043.2)
COBISS:	21943318
Views:	1507
Downloads:	360
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Validation of a method for Pb(II) analysis using SPE sensor
Secondary abstract:	Heavy metals are present all around us and pose a threat to animals and human beings. One of the methods for heavy metals determination that has been used in recent decades is polarography, which uses mercury electrode. Due to toxic properties of mercury, other methods are currently being sought that would replace mercury. The purpose of this work is partial method validation for Pb(II) analysis using SPE (screen-printed electrode) -sensor, which could be a good substitute for mercury electrode. SPEs are sensors with three electrode configuration (working, reference and counter electrode) printed on the same plastic or ceramic platform. Within the validation process, limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, precision and interference study were checked. First, the reversibility of electrode reaction using SPE-sensor was investigated with cyclic voltammetry (CV). Then the electroanalysis was preformed using square-wave anodic stripping voltammetry (SWASV). A carbon electrode on an SPE-sensor or modified antimony film carbon electrode (SbFSPE) were used as working electrodes. In the latter case, 0.01 M HCl and 0.5 mg/L Sb(III) medium was used for electrode formation. Partial method validation was carried out using both electrodes. For SbFSPE, the determined LOD and LOQ were 1.5 µg/L and 3.0 µg/L, respectively. In the case of SPE, the LOD and LOQ were determined to be 0.5 µg/L and 1.5 µg/L, respectively. Method is linear in the concentration range between 24.4 µg/L and 319.1 µg/L for SbFSPE and between 69.8 µg/L and 368.4 µg/L for SPE. The accuracy was checked by determining the concentration with multiple standard addition method at Pb(II) concentration of 169.1 µg/L. The precision was evaluated by calculating the relative standard deviation (RSD). In the sequential analysis of various sensors, accuracy and precision were significantly better for SbFSPE compared with SPE, when sensors were used for the first time. Accuracy and precision were exacerbated by the further use of SbFSPE, while SPE accuracy was improved when sensors were used for the second time. In successive use of the same sensor, accuracy was better for SPE compared to SbFSPE after five successive uses. Interference study showed that in the case of equal concentration of Cd(II) and Pb(II) the stripping signal for Pb(II) increased, whereas at mass concentration ratio of 1:10 peak for Pb(II) decreased. At 100-times higher concentration of Cd(II) compared to Pb(II) peaks overlapped and the peak for Pb(II) could not have been determined. Hg(II), Bi(III), Cu(II) and Sn(II) significantly influenced on stripping signal for Pb(II), whereas no major changes were observed in the presence of Zn(II), As(III), Na(I), Ca(II), Mg(II), K(I), Fe(III) and NO3- ions.
Secondary keywords:	validation;lead;antimony;heavy metals determiantion;SWASV;SPE;
URN:	URN:SI:UM:
Type (COBISS):	Bachelor thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	X, 56 str.
ID:	10942438