Sensors 2026 , 26 , 2049
4of 16
2. Materials and Methods 2.1. Reagents
All reagents used were analytical grade. Coating compounds for piezoelectric quartz crystals were Nafion 117 solution (Nafion), polyvinylpyrrolidone (PVP) and Tetrakis-2-hydroxy ethyl ethylenediamine (THEED) from Fluka (Buchs, Switzerland); Manganese (II) phthalocyanine (Mn-Pht) was from Sigma-Aldrich (Madrid, Spain), and two homemade compounds: chloro [5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato] manganese(III) (Mn(TPFPP)Cl) [13] and tetrabutylammonium Mn (III) polyoxotungstante (TBA-PMnW11) [14]. Solvents used to dissolve coating compounds were chloroform and tetrahydrofuran from Sigma-Aldrich (Madrid, Spain), ethanol from Carlo Erba (Val de Reuil, France) and acetone from VWR (Fontenay-sous-Bois, France). Nitrogen was Alphagaz from ArLíquido (Algés, Portugal). SPME fibers and holders were obtained from Supelco (Bellefonte, PA, USA). 2.2. Samples The office paper sheets are part of a personal collection. Office papers with 70 to 80 gsm were bought from markets around the globe, including Germany, Spain, Italy, France, the Netherlands, Russia, Dubai, and Latin America. Papers were not obtained directly through the manufacturers to assure that natural variability was present. Otherwise, samples may have undergone special selection and items could artificially be more homogeneous and standardized. However, this way of gathering samples results in incomplete specifications. Although the manufacturer of each paper is known, the country of production is sometimes uncertain, and for some samples there is no precise information regarding the tree species used as the fiber source. Beyond the lack of information, it is a remarkable collection of items, unlikely to be supplanted. All samples appeared identical to the naked eye. Table 1 summarizes the sample information. The symbol “?” was used whenever the information was not certain. The samples with complete information are shown in grey.
Table1. Characterization of office paper samples.
Paper Grammage (g)
Countryof Origin*
Year of Production
Market
Manufacturer
ID Type of Wood *
P1
Mix
80
France
MONDI
Slovakia?
2019
CLAIRE FONTAINE
P2
E. globulus ?
80
Germany
France
2019
INTERNATIONAL PAPER
P3
-
80
Russia
Russia?
2018
P4 P5 P6
-
80 70 75
Russia
MONDI
Russia? Nordic
2018 2019 2019
Birch
Germany
UPM
E. globulus ?
Italy
BURGO
Italy
INTERNATIONAL PAPER THE NAVIGATOR COMPANY (ATF) THE NAVIGATOR COMPANY (FIG)
P7
-
80
Germany
USA?
2018
P8
75
Portugal
Portugal
2019
E. globulus
P9
70
Portugal
Portugal
2019
E. globulus
https://doi.org/10.3390/s26072049
Made with FlippingBook interactive PDF creator