Določevanje težkih kovin v pijačah z ICP-OES

magistrsko delo

Ela Likovnik (Author), Matjaž Finšgar (Mentor), David Majer (Co-mentor)

Abstract

Magistrsko delo prikazuje delno validacijo tehnike induktivno sklopljene plazme z optično emisijsko spektroskopijo (ICP-OES) za določevanje ionov As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr in Zn v vzorcih pijač. Delno validacijo smo za vsak analit izvedli pri več valovnih dolžinah in med njimi izbrali eno valovno dolžino za vsak analit glede na zastavljen kriterij. Določili smo mejo zaznavnosti (LOD), mejo določljivosti (LOQ), linearno koncentracijsko območje, točnost in natančnost. Linearno koncentracijsko območje metode smo ovrednotili z izračunom kvadrata korelacijskega koeficienta (R2) in koeficienta kvalitete (QC), zastavljena kriterija sta bila R2 ≥ 0,9990 in QC ≤ 5,00 %. Natančnost smo ovrednotili z izračunom relativnega standardnega odmika, ki je bil za vse analite manjši od zastavljenega kriterija 20,0 %. Točnost metode smo potrjevali z izračunom izkoristkov meritev raztopin standarda znane koncentracije. Izkoristki so bili znotraj zastavljenega kriterija med 80,0 % in 120,0 %. Točnost določevanja koncentracije ionov kovin v vzorcih pijač smo preverili z izračuni izkoristkov, pri čemer smo vzorcem pijač dodali znano količino raztopine standarda. Slednjo točnost smo potrdili za vse ione kovin v vzorcih pijač znotraj zastavljenega kriterija. Vzorce pijač smo pred analizo z ICP-OES pripravili s pomočjo mikrovalovnega kislinskega razklopa v raztopini HNO3 in H2O2. Instrument smo pred merjenjem vzorcev pijač umerili in ga na vsakih 23 injiciranj ponovno umerili. Na ta način smo opazovali, kako se signal spreminja s številom injiciranj ter določili, na koliko injiciranj je potrebno narediti ponovno umerjanje instrumenta za določen analit. Ioni Se so bili edini ioni, ki jih nismo zaznali v nobenem od 25 testiranih vzorcev pijač (ali ionov Se ni bilo v vzorcih ali pa je bila koncentracija pod LOD). Ione Co smo zaznali v enem, Pb v štirih, As v desetih in Mo v enajstih vzorcih pijač, vendar jih ni bilo mogoče kvantificirati, saj so bile izmerjene koncentracije pod LOQ. Izmerjene vsebnosti ionov kovin v vzorcih pijač smo primerjali z mejnimi vrednostmi za vsebnost ionov kovin v pitni vodi, določenimi s strani Svetovne zdravstvene organizacije, Evropske agencije za varnost hrane in v Pravilniku o pitni vodi (Uradni list RS št. 19/2004). Previsoko vsebnost smo določili le pri merjenju vsebnosti ionov Mn v vzorcu ananasovega soka. Ioni kovin, ki smo jih določiti v ostalih vzorcih pijač, so bili pod mejnimi vrednostmi in posledično lahko trdimo, da uživanje analiziranih pijač ne predstavlja tveganja za zdravje.

Keywords

ICP-OES;mikrovalovni kislinski razklop;delna validacija metode;težke kovine;kovine v pijačah;magistrske naloge;

Data

Language:	Slovenian
Year of publishing:	2023
Typology:	2.09 - Master's Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[E. Likovnik]
UDC:	66.011:[621.311.24:622.997](043.2)
COBISS:	148480771
Views:	122
Downloads:	14
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Determination of heavy metals in drinks by ICP-OES
Secondary abstract:	This thesis presents partial method validation for the determination of As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr, and Zn ions in beverage samples using inductively coupled plasma with optical emission spectrometry (ICP-OES). Partial method validation at multiple wavelengths was performed for each analyte and one wavelength was selected for each analyte based on chosen criteria. The limit of detection (LOD), limit of quantification (LOQ), linear concentration range, precision and accuracy were determined. The linear concentration range was evaluated by calculating the square of the correlation coefficient (R2) and the quality coefficient (QC), with established criteria of R2 ≥ 0,9990 and QC ≤ 5,00 %. Precision was evaluated by calculating the relative standard deviation, which was below the established criteria of 20,0 % for all analytes. The accuracy of the method was evaluated by calculating the recoveries of the measurements of the standard solution with known concentration. The recoveries were within the established criteria of 80,0 % and 120,0 % for all analytes. The accuracy of determination of metal ion concentration in beverage samples was evaluated by calculating the recoveries, in which a known quantity of the standard solution was added to the beverage samples. The accuracy was confirmed for all metal ions in beverage samples within the established criterion. Before analyzing the beverage samples with ICP-OES, they were prepared by microwave-assisted acid digestion in a solution of HNO3 and H2O2. The instrument was calibrated before measuring the beverage samples, and it was recalibrated every 23 injections. In this way, we observed how the signal changes with the number of injections and determined how many injections were necessary to recalibrate the instrument for a given analyte. Se ions were the only ions that were not detected in any of the 25 real samples analyzed (either Se ions were not present in the samples, or the concentration was below LOD). We detected Co ions in one, Pb ions in four, As ions in ten and Mo ions in eleven beverage samples, but they could not be quantified because the concentrations measured were below LOQ. The concentrations of metal ions measured in beverage samples were compared with the limit values for metal ion content in drinking water, established by the World Health Organization, the European Food Safety Authority and in Drinking Water Regulations (Gazette RS, No. 19). Only the measurement of Mn ion content in pineapple juice showed a concentration above the limit. The metal ions that we determined in the other beverage samples were below the limit values and, consequently, it was established that the consumption of the beverages analyzed does not pose any health risk.
Secondary keywords:	ICP-OES;microwave-assisted acid digestion;partial method validation;heavy metals;metals in drinks;
Type (COBISS):	Master's thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	1 spletni vir (1 datoteka PDF (X, 55 f.))
ID:	18172452