Microplastics' analysis in water: Easy handling of samples by a new Thermal Extraction Desorption-Gas Chromatography-Mass Spectrometry (TED-GC/MS) methodology.

Thermal Extraction-Desorption (TED) using a thermobalance coupled to a gas chromatograph (GC) with mass spectrometer (MS) detector is an extended method for polymers identification in complex matrixes. A new TED-GC/MS method for microplastics identification is developed in this study, where the whole filter with solids collected from water is thermal treated in a furnace, instead of using a small portion in a Thermogravimetric analysis (TGA) device, avoiding sample handling. Pyrolyzing the whole filter in a tubular furnace has advantages with respect to the standard procedure of using a TGA with a small crucible in TED-GC/MS. The main advantage is the easy manipulation of the sample, since the filter does not have to be manipulated to extract the sample or cut some portions, avoiding sample losses during handling and ensuring that inhomogeneity on the filter surface is not a problem. Furthermore, there are no limitations on the weight of the sample beyond the adsorbent's ability to trap decomposition compounds without becoming saturated, so high intensity signals can be obtained in order to avoid confuse signals with noise, false negatives or values so close of the quantification limit.

Influence of brewing method and acidity regulators on the antioxidant capacity of coffee brews.

The antioxidant capacity of coffee brews prepared with different coffeemakers (filter, plunger, mocha, and espresso) was measured by colorimetric (total phenolic compounds and ABTS) and electron spin resonance (ESR) spectroscopy techniques (Fremy's salt and TEMPO). The mocha coffeemaker had the highest yield in coffee antioxidant extraction per gram of ground roasted coffee, but espresso coffee was richest in terms of antioxidant intake (per milliliter of coffee brew) followed by mocha, plunger, and filter. Both Folin-Ciocalteu (total phenolic compounds) and ABTS assays reacted with standard solutions of chlorogenic acids (CGA) and melanoidins (MO-Ala and MO-Gly). However, Fremy's salt was mainly scavenged by chlorogenic acids, whereas the stabilized radical TEMPO was effectively scavenged by melanoidins, but not by chlorogenic acids. Thus, ESR spectroscopy allows distinguishing between phenolic and nonphenolic antioxidants. Moreover, the addition of pH-regulator agents to coffee, such as sodium carbonate (75 ppm) and bicarbonate (75 ppm), to extend its shelf life, slightly increases the pH, modifying the antioxidant capacity in those coffee brews with the highest capacity (mocha and espresso).