Determination of Nanoplastics Using a Novel Contactless Conductivity Detector with Controllable Geometric Parameters

Abstract

Plastic waste in the environment is continuously degraded to form nanoplastic particles, and its harm has attracted widespread attention. At present, the identification and quantification of nanoplastics are performed by visual observation and using some spectroscopy methods, which are time-consuming and lack accuracy. Therefore, this study proposes a contactless conductivity detector (C 4 D) based on a glass microfluidic chip with controllable geometric parameters to quantify nanoplastics. We found that when the insulating layer thickness was 15 μm, the electrode spacing was 1 mm, and the shielding method was on-chip shielding, the detector displayed the best performance. The detector possesses a simple structure with high sensitivity and outstanding reproducibility, that is, the limit of detection of KCl solutions can reach the micromolar level, and the intraday RSD is 0.2% (n = 5). This work uses a microfluidic chip C 4 D to study nanoplastics for the first time, and the limit of detection is 0.25 μg/mL and the quantitative limit is 0.8 μg/mL. In addition, plant experiments have verified that terrestrial plants can absorb nanoplastics in water, expanding the application of contactless conductivity detectors and providing a new method for the quantitative analysis of nanoplastics.

Simple microfluidic device for simultaneous extraction and detection of microplastics in water using DC electrical signal

“…Unlike previous RPS 40–43 or C 4 D 35 sensors in which resistive pulses were observed at the presence of the microplastic beads, our sensor showed a conductive response demonstrated by a decreasing trend in resistance after adding microplastics to the channel (Fig. 5).…”

“…More importantly, microfluidic sensors have emerged as potential tools to pave the way for high-throughput, label-free, real-time, and point-of-need detection of microplastics. For instance, integration of microfluidic channels and electrical detection methods such as capacitively contactless coupled conductivity detection (C 4 D) 34,35 and Coulter counter, also known as the resistive pulse sensor (RPS), 36 has led to emergence of new devices with attractive features such as simple construction, low cost, and portability.…”

“…42 Moreover, expensive, and time-consuming procedures are involved in fabrication and installation of electrodes into C 4 D and RPS sensors. 35,42,46…”

“…The above electro-fluidic sensors have found a wide range of applications in environmental monitoring of bacteria, 37 algae, 38 heavy metals 39 and most recently, microplastics. 35,[40][41][42][43][44][45] The detection mechanism in C 4 D and RPS is based on monitoring the temporary changes in current caused by translocation of small particles through (or very close to) a sensing gate, which is usually a thin insulating layer in C 4 D sensors and a narrow constriction (orifice) in RPS sensors. [34][35][36] These techniques offer unique advantages in counting and determination of shape and volume estimates for individual particles.…”

Revealing Trace Nanoplastics in Food Packages─An Electrochemical Approach Facilitated by Synergistic Attraction of Electrostatics and Hydrophobicity

“…Electrochemical sensing strategies have displayed their advantages on rapid, sensitive, selective, and low-cost detection of various analytes. , Herein, we developed a facile sandwich-type electrochemical sensor for the quantification of nanoplastics. Positively charged Au nanoparticles ((+)­AuNPs) were coated onto a Au electrode to selectively capture negatively charged nanoplastics in an aqueous environment.…”