A procedure using disposable pipette tips adapted for solid-phase extraction, known as DPX SPE, was used as an alternative way for the chromium determination in wastewater samples. DPX-SPE consists of a device which allows a dynamic contact between the sample and the solid-phase. A residue obtained from the processing of coffee beans, denominate coffee silverskin, was used as a new adsorbent. Characterization techniques revealed properties of lignocellulosic materials with potential application for chromium adsorption. The parameters including adsorbent mass (25.00 mg), elution solvent (0.1 mol L-1 HCl, 200 μL) and pH (2.0) were optimized. Thus, 1.00 mL of deionized water for conditioning, 4.00 mL of sample, 2 extraction cycles and 1 elution cycle were the employed conditions. Enrichment factor of 12, limit of detection of 6.00 µg L-1 and relative standard deviation (RSD) 1.3% (n = 3) were obtained. The method proved to be fast, cheap, environmentally friendly, and simple, providing good recoveries (104-113%), and it was satisfactorily applied in real samples.

Molecular absorbance and fluorescence measurements are usually performed by benchtop or portable USB spectrophotometers or fluorometers. However, even the simplest configuration of these instruments requires considerable financial input, which is not affordable to many universities and research groups especially when public politics withdraw funds from science. Light-emitting diodes (LEDs) based devices can be an interesting alternative for low-cost, portable yet reliable measurements of absorbance of fluorescence. Especially if associated with the fabrication of 3D structures by additive manufacturing techniques. Although there are many reviews in the literature dedicated to discussing the theoretical aspects and analytical performance of LED-based devices, we consider that these reviews are not easily applicable for beginners in electronics. It results in the intimidation to employ such powerful tools which could have a huge impact mainly to small and/or initial groups. In this tutorial, we present a guide that will help students and researchers to construct “lab-built” devices based on simple optoelectronic components and 3D printing to perform molecular absorbance and fluorescence measurements for analytical methods. Finally, with this tutorial guide, we anticipate a large spread of the usage of LED devices for reliable analytical measurements that can be extensively used in many scenarios.

Food safety is a constant and necessary concern due to the worldwide increase of the food demand. The monitoring of quality parameters demands the development of accurate, easy and fast procedures. The aim of this work was to develop a cheap, miniaturized and trustworthy salting-out assisted liquid-liquid extraction (SALLE) procedure for the determination of pesticides in wines. Sample and acetonitrile were mixed and the addition of NaCl and CH3COONa were used for separation of aqueous and organic phases. After centrifugation, the organic phase was directly injected into a liquid chromatograph. The developed SALLE procedure consumed at least 25-fold less reagent compared to conventional QuEChERS procedure. Additionally, the d-SPE step of the QuEChERS method was suppressed, without efficiency losses. The developed procedure was compared to the conventional methodology and no significant difference was observed. It was successfully applied to the determination of three pesticides in wines by liquid chromatography. Low consumption of sample and solvent, low residues generation, simple instrumentation are notable advantages. The suppression of the d-SPE step simplified the process and the risk of analyte losses.

This work presents a simple electrochemical method for 2-naphthylamine (2NAP) determination in perfume by differential-pulse voltammetry (DPV) employing a boron-doped diamond (BDD) electrode cathodically treated. Simple dilution of sample in supporting electrolyte was performed before electrochemical analysis. A borate buffer solution of pH 10.0 containing 20% (v/ (LOD) of 0.0046 µmol L-1 with a linear range between 0.5 and 90 µmol L-1, and RSD < 2.9%, respectively. Recovery values for spiked samples with 2NAP were between 102 and 104%. The proposed method is feasible to be applied for 2NAP detection and quantification on perfume samples with simple sample preparation.

This paper presents a simple and low-cost capillary electrophoresis method for ultra-fast simultaneous determination of naphazoline (NPZ) and one of the following active ingredients: diphenhydramine (DIP), pheniramine (PHEN) or chlorpheniramine (CPHEN). The proposed method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) equipped with a short length capillary column (10 cm). One sample can be analyzed every 35 s (ca. 100 injections per hour) with resolutions between peaks greater than 1.4. The optimized background electrolyte (BGE) was composed by 20 mmol L-1 histidine and 10 mmol L-1 3,4-dimethoxycinnamic acid (pH = 9.5, adjusted with NaOH). Limits of detection were 25 µmol L-1 for NPZ, DIP, and PHEN and 13 µmol L-1 for CPHEN. The results obtained with the developed procedure were compared to those obtained by high-performance liquid chromatography (HPLC) and no statistically significant differences were observed (95% confidence level).

ABSTRACT Coupling solid-phase extraction (SPE) to flow systems has promoted a synergistic development. Whereas SPE mechanization leads to improved precision and higher sample throughput, as well as diminishes systematic errors and contamination risks, analyte concentration and separation from the sample matrix provides a remarkable impact on detectability and selectivity in flow analysis. Historical aspects, main cornerstones, tips for system design, and recent applications are critically reviewed, in the context of analyte(s) separation/concentration, sample clean-up, and release of sorbed chemical species involving both packed (e.g. mini-columns, cartridges, and disks) or fluidized (e.g. beads and magnetic materials) particles. Novel (bio)sorbents, selective synthetic materials, and stationary phases for low-pressure chromatography are also discussed. Moreover, the feasibility of SPE for sample treatment before chromatographic separation, as well as the exploitation of direct measurements on the solid phase (optosensing) are emphasized.