A lab-on-a-tip approach to make electroanalysis user-friendly and de-centralized: Detection of copper ions in river water

Abstract

The development of portable and user-friendly sensing platforms is a hot topic in the field of analytical chemistry. Among others, electroanalytical approaches exhibit a high amenability for reaching this purpose, i.e. the commercial strips for diabetes care are an obvious success. However, providing fully-integrated and user-friendly methods is the leitmotiv. In this work we evaluate the use of a disposable pipette tip, opportunely configured, to realize the first example of lab-on-a-tip. The combination of a pipette tip, wire electrodes, and cotton wool filter, highlights the suitability of producing a novel one-shot electroanalytical platform that does not require expertise-required tasks. To demonstrate the feasibility of this novel method, copper (Cu) is detected in water samples by means of anodic stripping voltammetry. The quantification is performed directly into the tip that contains a cotton wool filter: the filter has the double function of purifying the matrices from gross impurities and releasing all the pre-loaded reagents necessary for the assay. After optimizing the experimental parameters, the lab-on-a-tip was capable of detecting Cu linearly up to 300 μg/L with a detection limit of 6.3 μg/L. The effectiveness of the platform was confirmed by testing 50, 100, and 150 ppb Cu-spiked river water sample with recovery value comprised between 92 and 103%.

Femtomolar detection of Cu2+ ions in solution using super-Nernstian FET-sensor with a lipid monolayer as top-gate dielectric

“…Ion sensors are required in many domains of the society including environment (Cinti et al, 2018;Brezoczki et al, 2017;Strungaru et al, 2018), technology (Arbadi et al, 2016) and security (Zhang et al, 2018) with the highest societal impact in the biomedical field (Kubala-Kukuś et al, 2014;Wustoni et al, 2015). The detection of low concentration molecules/ions of biological or physiological interest in the body with high sensitivity and selectivity is an ultimate goal that offers new opportunities in the early diagnostic and treatment of diseases.…”

“…They also often require pre-concentration and/or filtering of the analytes, which all together prevent on-site, real time detection or systematic analysis. Recently more suitable devices for low cost and on-site measurements have been developed based on both colorimetric (Gao et al, 2017) and fluorescence (Zhang et al, 2018;Liu et al, 2018) optical spectroscopies, electrochemical (Cinti et al, 2018) or photo-electrochemical (Wang et al, 2018) techniques combined with a metal-ligand to increase selectivity. However, most of these devices are limited in term of LOD to the nanomolar or picomolar range.…”

Combining In-Tip Reaction and Infrared Thermal Imaging for Fast and Portable Enthalpimetric Analysis

“…The search for portability in chemical analysis has increased, looking to obtain results in loco and helping rapid decisions. In this way, sample preservation can be not required as in classical methods, and the transport of samples to the analytical laboratories can be avoided …”

“…These devices are generally equipped with disposable polymeric tips, which are often used passively only to liquid transfer. However, other analytical operations could be performed directly in the pipette tips, including sample preparation or even the direct determination of analytes. − …”

“…In addition to sample preparation, the entire analytical process can be performed directly in a pipette tip. In this sense, a lab-on-a-tip method using cotton wool inside a pipette tip to both remove the interferents from the sample matrix and also release the reagents for the determination of copper (Cu 2+ ) in water samples with anodic stripping voltammetry has been proposed . Another approach for the direct in-tip determination of analytes was recently proposed, which allowed UV–vis measurements through a disposable pipette tip rather than a conventional cuvette used in spectrophotometry. , Polymeric materials that transmit light in the range from 260 to 1050 nm were used, and some applications were feasible as for nucleic acid analysis …”