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Ozone is an oxidizing molecule used for disinfecting a wide variety of environments, such as in dental clinics, and has most recently been promoted as a sanitizing agent to prevent coronavirus transmission. The easy access to ozone-generating sources also enables their ubiquitous use. However, exposure to ozone may seriously affect human health by amplifying or inducing respiratory diseases and distress syndromes and has been associated with premature deaths from other diseases. In this scenario, miniaturized, low-cost, and portable optical sensors based on the absorption signature of ozone in the ultraviolet (UV) range of the electromagnetic spectrum are an innovative approach for providing real-time monitoring of gaseous ozone, ensuring the safety of indoor and workplace environments. In this paper, a miniaturized ozone sensor based on the absorption signature of ozone at deep-UV frequencies was developed by integration of so-called substrate-integrated hollow waveguides (iHWG) with a miniaturized ultraviolet lamp and a fiber-optic USB-connected spectrophotometer. The innovative concept of iHWGs facilitates unprecedented compact dimensions with a high degree of flexibility in the optical design of the actual photon absorption path. The proposed device rapidly responded to the presence of ozone (<1 min) and revealed a suitable linearity (r 2 > 0.99) in the evaluated concentration range. The limit of detection was determined at 29.4 ppbv, which renders the device suitable for measurements in the threshold range of the main regulatory agencies. Given the adaptability and modularity of this platform, we anticipate the application of this innovative concept to be equally suitable for the in situ and real-time analysis of other relevant gases providing suitable UV absorption signatures.

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Alcoholic beverages contaminated with scopolamine (SCP) are often employed for criminal purposes due to their sedative effect. The determination of the residual levels of SCP in body fluids (e.g., urine) can help to track possible victims of induced ingestions. Biological sample analysis usually requires a preconcentration step to enhance their detectability and to provide sample clean-up. Molecularly imprinted polymers (MIPs) in lieu of conventional solid sorbents represent an enhancement of selectivity, due to their specific recognition sites. Additionally, the adaptation of the solid-phase extraction (SPE) cartridge into a disposable pipette tip extraction (DPX) contributes to the miniaturization of the sample preparation step. Herein, an analytical method for the determination of SCP in synthetic urine samples via the integration of molecularly imprinted solid-phase extraction (MISPE) with DPX as a preconcentration step prior to capillary electrophoresis analysis (also known as MISPE-DPX-CE) is presented. The extraction and elution steps were optimized using a factorial design. Using the optimized conditions, a preconcentration factor of 20 was obtained, leading to a working range of 0.5–6 µM with LOD of 0.04 µM and repeatability of 6.4% (n = 7) and adequate recovery values (84 and 101%) The proposed MISPE-DPX-CE approach was successfully applied to selective extraction, preconcentration, and determination of SCP in synthetic urine samples.

The solid phase extraction technique (SPE) is widely used in the extraction and preconcentration stages of the most analytical species and it can also be applied in the removal of heavy metals. The SPE can be adapted for the use of disposable tips, known as DPX (disposable pipette extraction) method. In this study, a procedure was developed for preconcentration of Cr (III), using a bark of coffee as adsorbent and DPX and determination by flame atomic absorption spectrometry (F AAS). Preliminary tests were performed to choose the treatment of adsorbent (in natura, HCl, NaOH and hexane). Infrared spectrometry, thermogravimetric analysis, scanning electron microscopy, and dispersive energy spectroscopy techniques were used to characterize the adsorvent material. The kinetic study of the adsorption process of Cr (III) by the adsorbent showed that the adsorption equilibrium was reached in 10 minutes, with removal of up to 50% using 25 mg of adsorbent. The kinetic models of pseudofirst order and pseudo-second order were used to evaluate experimental data. Langmuir, and Freundlich models were used to understand the adsorption mechanism. For the preconcentration of Cr (III) by DPX, the steps such as conditioning the extractive phase, sample aspiration, air aspiration, sample dispensing and elution were optimized to establish the best equilibrium condition. Thus, 1 mL of deionized water for conditioning, 4 mL of solution, 25 mg of solid phase, 2 cycles of extraction, 200 μL of HCl in 1 elution cycle were the optimized conditions. The study showed the viability of the use of the bark of in natura coffee for Cr (III) extraction and preconcentration. On optimized conditions, the calibration curve was linear in the range of 0.02-1.00 mg L-1. The limits of detection and quantification achieved were 0.0062 and 0.0207 mg L-1 respectively, obtaining an enrichment factor of 11 and the value corresponding to the relative standard deviation (D.P.R.) for 10 replicates were below 5%. The accuracy of the method was tested using certified material. Recovery values were obtained between 103 to 104% for fortified samples. The method was applied satisfactorily for the determination of Cr (III) in water samples. The study showed the feasibility of using the in natura coffee film for Cr (III) extraction and preconcentration.