Advances in the use of 3D printing technology have led to the development of new low-cost devices. This technology features high versatility, considering the easy modulation of the materials depending on its objectives and applications. In this sense, we have developed a laboratory-built contact angle measuring device (lab-made). The device was composed by the assembly of 26 3D-printed pieces of different sizes and design printed using acrylonitrile-butadiene-styrene polymer. The device was designed in three main parts. The first part was related to the analysis, with the use of platforms for the sample surfaces positioning. The second part was made to support a micropipette, prepared to add the drop for analysis; and the third for the support of a smartphone, utilized to obtain the images. The device was applied for the measurement of contact angle on different surfaces, demonstrating its versatility and precision of the results. The obtained values are in accordance with others found in the literature. The developed device presented a low-cost (US$ 25.34 per device), easy assembly and operation.

The construction of a low cost mini sensor containing a bismuth-film electrode (BiFE), as work electrode, a silver electrode as pseudo reference electrode, and copper as counter electrode is proposed. The application of this mini sensor using a low cost electrochemical cell for in loco voltammetric determinations of inorganic and organic analytes is also described.

A factorial design applied in a voltammetric stripping method for the measurement of Ag(I) in natural water is described. The procedure is based on the effective pre-concentration of silver ions on electrode surface. The calibration graph was linear in the silver concentration range from 7.92 x 10"7 to 1.07 x 10"5 mol L"1 with a detection limit of 3.81 x 10-7 mol L-1. The determination of Ag(I) in natural water samples was carried out satisfactory with the proposed electrode.

A method employing chitosan as complexant agent in the removal of copper(II) ions generally present in the Brazilian cachaça samples is herein proposed. The efficiency of this method is attributed to its high capacity of metal cations adsorption, mainly due to presence of hydroxyl and amine groups that can serve as chelating sites. The removal of copper(II) ions from this alcoholic beverage was efficient employing either in column and batch system. The analysis were carried out employing the flame atomic absorption spectrometry and the remaining copper(II) concentrations in the treated cachaça were lower than LOD of FAAS technique.

A flow injection chemiluminescence method for the determination of paracetamol in pharmaceutical formulations is described. It is based on the consumption of the sodium hypochlorite by paracetamol and decreases of the analytical signal. The analytical curve was linear in the paracetamol concentration range from 5.0 x 10-6 to 5.0 x 10-5 mol L-1, with a detection limit of 1.8 x 10-6 mol L-1. The RSDs were 2.0 and 1.2% respectively for 2.0 x 10-5 and 4.0 x 10-5 mol L-1 paracetamol solutions (n = 10) and a sampling frequency of 180 h-1 was obtained.