Edwin Palacio

A 3D-printed device was designed and printed by a stereolithographic technique (SLA) and coated with a highly selective solid phase extraction resin for on-site diclofenac extraction from wastewater, avoiding the transport and treatment of large volumes of samples in the laboratory. The best results in terms of chemical and mechanical resistance were obtained with Rigid 10K resin. The “stick-and-cure” impregnation technique was used to coat the 3D-printed device with Oasis^® HLB resin. The coated 3D-printed device can be reused up to eight times without losing extraction efficiency. The eluent and derivatization reagent volumes were optimized by a multivariate design. The proposed method allowed for the extraction and determination of diclofenac by PTV-GC-MS, achieving methodological detection and quantification limits of 0.019 and 0.055 μg L⁻¹, respectively, with a preconcentration factor of 46. The analysis time was 23 min per sample. To validate the proposed methodology, addition/recovery tests were carried out in different wastewater samples, obtaining recoveries above 90%. The methodology was applied at the wastewater treatment plant (WWTP) of Calvià (Mallorca, Spain), finding diclofenac in concentrations of 15.39 ± 0.07 μg L⁻¹ at the input of the primary decantation process, 4.48 ± 0.03 μg L⁻¹ at the output of the secondary decantation, and 0.099 ± 0.001 μg L⁻¹ at the output of the tertiary treatment, demonstrating the feasibility of the on-site extraction method in monitoring diclofenac over a wide concentration range. Finally, a greenness index of 0.58 for the proposed on-site sample preparation was achieved according to the AGREEprep metrics, making it an eco-friendly alternative for diclofenac monitoring.

The development of a portable device created by 3D printing for colorimetric and fluorometric measurements is an efficient tool for analytical applications in situ or in the laboratory presenting a wide field of applications in the environmental and food field. This device uses a light-emitting diode (LED) as radiation source and a webcam as a detector. Digital images obtained by the interaction between the radiation source and the sample were analyzed using a programming language developed in Matlab (Mathworks Inc., Natick, MA, USA), which builds the calibration curves in real-time using the RGB colour model. In addition, the entire system is connected to a notebook which serves as an LED and detector power supply without the need for any additional power source. The proposed device was used for the determination in situ of norfloxacin, allura red, and quinine in water and beverages samples, respectively. For the validation of the developed system, the results obtained were compared with a conventional spectrophotometer and spectrofluorometer respectively with a t-test at a 95% confidence level, which provides satisfactory precision and accuracy values.