Use of non-degradable plastics in food packaging is alarming for the environment as they are often thrown away after short consumption. Though papers are replacing plastics in different sectors, their low water resistance limits their use in food packaging. in the past, water-resistant papers have been fabricated, but the natural degradability of the paper has been compensated. This study proposes water-resistant yet biodegradable papers from naturally abundant wastes, such as banana plant (BP) and water hyacinth (WH) and validates their properties for practical packaging uses. The resources were completely used, avoiding generation of any in-process biomass residue. This study for the first time reports the impact of ethyl cellulose (EC) coating (∼10 μm) on paper surfaces. The morphology and chemical analysis of the coated papers confirmed the consistent formation of EC layer on paper surfaces. The presence of EC significantly reduced the vapour transmission (22–30%) and moisture content (6–11%) of the papers. Water drops were stable on the coated surfaces at least for 20 min and then were wiped off leaving a dry surface. EC coating considerably increased the tensile index, i.e., 13–17% for BP and 20–35% for WH, though elongation and modulus properties remained almost unchanged. All the papers showed ultraviolet (UV)-resistance, while the coated papers were more transparent in the visible light region. Overall results confirmed the potential of the proposed EC-coated papers as a promising alternative to single-use plastics in food packaging.

Adsorption isotherms of 3 selected paper-based packaging materials, that is, vegetable parchment (VP) paper, Kraft paper, and solid-bleached-sulfate (SBS) paperboard, were determined at 3 different temperatures (25, 40, and 50 °C). The GAB isotherm model was found to fit adequately for describing experimental adsorption isotherm data for the paper samples. The monolayer moisture content of the paper samples decreased with increase in temperature, which is in the range of 0.0345 to 0.0246, 0.0301 to 0.0238, and 0.0318 to 0.0243 g water/g solid for the MG paper, the Kraft paper, and the SBS paperboard, respectively. The net isosteric heats of sorption (qst) for the paper samples decreased exponentially with increase in moisture content after reaching the maximum values of 18.51, 27.39, and 26.80 kJ/mol for the VP paper, the Kraft paper, and the SBS paperboard, respectively, at low-moisture content. The differential enthalpy and entropy of 3 paper samples showed compensation phenomenon with the isokinetic temperature of 399.7 K indicating that water vapor had been adsorbed onto the paper samples with the same mechanism. Depending on the paper material, tensile strength of paper samples was affected by moisture content.

The growing demand for traceable and reliable results in analytical chemistry can be illustrated with the growth in ISO/IEC 17025 accreditation. Among different technical requirements in this quality system, the use of CRMs is highlighted because of its applications in many operations, such as method validation, proficiency tests, estimation of the uncertainties and quality control.Over the past several years, there has been an increased need to use different types of CRMs in chemical analysis, new CRM publications about its developments and certification. This paper proposes to show a detailed review considering the development of certified reference materials (CRM) for chemical analysis, focusing on food, water, soil and sediment matrices. An evaluation of the trends and best-applied practices in its development in the last 2 years was performed, to guide new developments for this material that is increasingly necessary to laboratories.

Correction for ‘A highly sensitive and selective fluorescent probe for quantitative detection of Al³⁺ in food, water, and living cells’ by Qian Jiang et al., RSC Adv., 2019, 9, 10414–10419.