Vrednotenje enostavnih testov za določanje bakrovih ionov za uporabo na materialih kulturne dediščine

Tomšič, Žan (author), Malešič, Jasna (mentor)

Baker je prehodna kovina, ki lahko katalizira homolitsko razgradnjo peroksidov, kar vodi do pospešene razgradnje celuloze, ki je glavna sestavina papirja. Višje vsebnosti bakra v historičnih papirjih so običajno posledica postopka izdelave papirja ali uporabe bakrovih pigmentov ter nekaterih železo-taninskih črnil. Posledice razgradnje se kažejo v slabšanju mehanskih lastnost papirja, v najhujših primerih celo naluknjanosti papirja na področjih nanosa pigmenta ali črnila. Konserviranje-restavriranje kulturne dediščine je naloga konservatorjev-restavratorjev. Poznavanje sestave materialov ter vzrokov za ragradnjo kulturne dediščine jim pomaga pri ohranjanju. Žal pa pogosto nimajo dostopa do inštrumentalnih tehnik, s katerimi lahko enostavno določimo prisotnost bakra v vzorcih. Zato sem v tem delu preveril različne komercialne teste za določevanje bakra v papirju ali jih pripravil sam in ovrednotil mejo zaznave in posledice uporabe testov na različnih vzorcih. Testiral sem Whatmanove filtrirne papirje, na katere sem nanesel različne bakrove soli, Whatmanove papirje z nanesenimi mešanicami ionov ter različno historično nepomembne realne vzorce. Vsebnost bakra v vzorcih sem določil z atomsko absorpcijsko spektroskopijo. Pri realnih, historičnih vzorcih sem uporabil rentgensko fluorescenčno spektroskopija. Atomsko absorcpijsko spektroskopijo sem uporabil le za modelne vzorce, ki sem jih pripravil sam, saj je to destruktivna metoda in zahteva vzorčenje večje površine vzorca. Pri vzorcih, kjer nismo določali koncentracije bakra, ampak zgolj njegovo prisotnost in smo imeli na voljo manjšo površino vzorca, pa smo uporabili rentgensko fluorescenčno spektroskopijo. Cuprotesmo so komercialno dostopni testni papirji za določanje bakra in bakrovih ionov na različnih površina ter v pepelu in imajo relativno visoko mejo zaznave bakra v vzorcih. Njihova uporaba povzroči madeže na testiranih papirjih, kar ni sprejemljivo za uporabo na materialih kulturne dediščine. Drugi testni papirji, ki sem jih pripravil v skladu z literaturo in po avtorju prispevka poimenoval Hulthe imajo zelo nizko mejo zaznave in pustijo na testiranih papirjih najmanj sprememb. Tretji testni papirji, ki so jih razvili na Inštitutu za kulturno dediščino Nizozemske s kratico ICN pa imajo višjo mejo zaznave kot Hulthe, ampak nižjo kot Cuprotesmo in pustijo manj sprememb kot Cuprotesmo. Interference ostalih kovinskih ionov so se pojavile le pri testih ICN.

• Language: Slovenian
• Keywords: kulturna dediščina, baker, testiranje, AAS, XRF
• Work type: Master's thesis/paper
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2026
• PID: 20.500.12556/RUL-186748
• Publication date in RUL: 04.09.2026

Secondary language

• Language: English
• Title: Evaluation of simple tests for the determination of cooper ions for use on cultural heritage materials

Abstract

Copper is a transition metal that catalyses the homolytic decomposition of peroxides, leading to accelerated degradation of cellulose, the main component of paper. Higher copper concentrations in historical papers are usually associated with the papermaking process or with the use of copper-containing pigments and certain iron-gall inks. The degradation manifests itself in the deterioration of the mechanical properties of paper and, in the most severe cases, can lead to complete loss of the paper substrate in areas where pigments or inks have been applied. The conservation of cultural heritage is the responsibility of conservators. Knowledge of the composition of cultural heritage materials is essential for developing appropriate strategies for their preservation. However, conservators often do not have access to instrumental techniques that can readily determine the amount of copper in samples. Therefore, in this thesis, I evaluated various commercially available and laboratory-prepared tests for copper detection, assessed their detection limits, and investigated the effects of their application on different types of samples. The tests were evaluated using Whatman paper treated with copper solutions, Whatman paper containing mixtures of various ions, and a range of real historic paper samples. Since it was necessary to confirm the presence of copper in the samples, its presence was verified using atomic absorption spectroscopy (AAS) and X-ray fluorescence spectroscopy (XRF). AAS was used only for model samples because it is a destructive technique and is therefore unsuitable for the analysis of cultural heritage objects. Real historic paper samples were also analysed using X-ray fluorescence spectroscopy XRF. The commercial Cuprotesmo tests showed a relatively high detection limit for copper and caused the most pronounced changes in both model papers and real samples. The Hulthe tests exhibited a very low detection limit and caused the least pronounced changes. The ICN tests had a higher detection limit than the Hulthe tests but a lower one than the Cuprotesmo tests, while causing less pronounced changes than Cuprotesmo. Interference from other metal ions was observed only with the ICN tests.

• Keywords: cultural heritage, copper, testing, AAS, XRF