# Biodegradable and Compostable Shopping Bags under Investigation by FTIR Spectroscopy
###### Abstract
The last legislative intervention happened in 2017, when the Italian Parliament, approving the Mezzogiorno decree, and from 1 January 2018 imposed the use of biodegradable ultralight bags for weighing and pricing bulk products, such as fruits and vegetables, with a small charge visible on the receipt [12]. The decree incorporated the \"EU directive 2015/720\" [9] and repeals the previous discipline (Article 2 of Legislative Decree 2/2012) and was applied to all plastic bags (Table 1). \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{3}{c}{**Type of Bag**} \\ \hline With handles & \\ \hline Without handles & \\ Transport of goods & \\ Transport of products & \\ \end{tabular}
\end{table} 
Table 1: Main types of polymer-based bags to which the new legislation [12] applies. According to the law [12], ultralight bags (with a thickness less than 20 \(\upmu\)m) must be biodegradable and 100% compostable, and by 2021, they will have to be composed of at least 60% of renewable raw materials (vegetable). According to Plastic Consult (2020), which, since 1979, offers consulting and business intelligence in the petrochemical and plastic materials sector, in 2019, 30% of shoppers present in the market were still not in compliance with regulations [13]. It is therefore clear that the development of a rapid method, usable by authorities, customers, and dealers to rapidly establish the components of the shopping bags could be extremely useful. Italy, as well as several European countries, with the aim of protecting consumers and the environment, with the law \"UNI EN 13432:2002\" [11], also requires the manufacturer ensure that the films of the shopping bags are controlled by a third party. This in order to verify the actual compostability of the products placed on the market. Manufacturers of compostable products can obtain certification from a number of certification bodies, which must evaluate and certify their compliance with a specified standard, primarily EN 13432 or ASTM D6400. In Europe, the most important certification schemes for establishing the compliance to EN 13432 are the DIN-CERTCO (Berlin, Germany), the OK-Compost label of TUV AUSTRIA (formerly the Belgian OK-Compost label of VINCOTTE), and the Italian COMPOSTABLE-CIC schemes. The bodies in charge of verification have no connection with the producers of these bags, other than the commercial one. In this way, the utmost seriousness, professionalism, and independence are guaranteed in carrying out the evaluation procedures. Products that meet the test criteria specified in the standards are eligible to receive the certification. Examples of certification labels are shown in Figure 1.  
Once obtained, the certification of conformity is valid generally for five years and confers the right to use the brand for marketing and advertisement purposes. During this period, the certification bodies can perform verification tests on the physicochemical characteristics of films produced by packaging industries responsible for the certified film products. In this regard, Fourier-Transform Infrared (FTIR) spectroscopy is an analytical technique routinely applied in various sectors of industry for performing similar studies. To obtain reliable information from the FTIR spectra of several samples, very similar to each other in terms of physicochemical characteristics, it is necessary to resort to specific analytical techniques, able to work on a series of very complex data, arranged in very large matrices, such as multivariate analysis (MVR), including Principal Component Analysis (PCA) [14]. In PCA, multi-dimensional data are reduced to a small number of new variables, principal components (PCs), which are orthogonal linear combinations of the original ones, which efficiently represent data variability in low dimensions [15].