Development of cloth-based microfluidic devices for rapid determination of histamine in fish and fishery products

A cloth-based analytical device combined with electrochemiluminescence detection (CAD-ECL) was described for rapid determination  of histamine (HA). The CAD device was produced by screen-printing a conductive carbon ink onto a patterned hydrophobic electrochemical microfluidic chamber to fabricate the three-carbon electrode system on a single hydrophilic cloth. The introduction of carbon nanodots linked to chitosan on the working carbon electrode surface enhanced the catalytic performance and overcame the resistance of the cotton fiber material. On this basis, the enhancement of the electrochemiluminescence (ECL) signal of the tris(2,2'-bipyridyl) ruthenium(II) complex, caused by HA, was observed in a phosphate buffer solution at pH 7.6. The proposed CAD-ECL sensor was successfully applied to the quantification of HA in fish and fishery samples with good linearity between ECL intensity and the logarithm of HA concentration in the range 1.0 to 1000.0 µg L^-1 with a low detection limit of 0.82 µg L^-1.

Fabrication of a simple 3D-printed microfluidic device with embedded electrochemiluminescence detection for rapid determination of sibutramine in dietary supplements

The design and fabrication of a simple 3D-printed platform with embedded electrochemiluminescence (ECL) detection for sibutramine determination is described. The microfluidic platform was fabricated by the fused deposition 3D-printing technique with polylactic acid filament, facilitated by computer-aided design (CAD). A three-electrode system was integrated into the device using graphene carbon paste as a working electrode, Ag/AgCl wire as a reference, and a graphite rod as a counter electrode. A further modification was carried out by applying bimetallic Au-Pt nanoparticle-supported multi-walled carbon nanotubes (MWCNT-Au-Pt) on the working electrode surface to enhance the electrocatalytic performance by exploiting the unique properties of nanomaterials. The analytical feasibility of the CAD-ECL sensor was tested through its application for the determination of sibutramine in dietary supplements. Under the optimized conditions, based on the enhancing effect of luminol emission, the device exhibited a linear calibration curve of the logarithmic sibutramine concentration versus ECL intensity in the range 5 × 10^-3 to 1 ng mL^-1. The limit of detection was 3 pg mL^-1 with a relative standard deviation of 1.7% (n = 15). The 3D-printed prototype can be successfully applied to a small-scale analysis in a simple and cost-effective approach.

A cloth-based electrochemiluminescence sensor for determination of salbutamol residues in pork samples

The fabrication of a cloth-based analytical device combined with electrochemiluminescence detection was established for the rapid determination of salbutamol in pork samples. A hand-coloring method to pattern the hydrophobic chamber was employed, and a three-carbon electrode system was subsequently screen printed onto the patterned cotton chamber. Further modifications of the working electrode surface were conducted using platinum nanoparticles and chitosan solution. The salbutamol enhanced the electrochemiluminescence signal of tris(2,2'-bipyridyl)ruthenium(II) complex in the Britton-Robinson buffer of pH 9.5 and the potential quantitative assay for SAL detection was exhibited. The proposed sensor illustrated a linear calibration curve of the logarithmic SAL concentration in the range of 5 × 10^-2 to 5 × 10⁴ µg L^-1 (r² > 0.996). A limit of detection of 6.8 ng L^-1 was observed. The CAD-ECL sensor was successfully applied for the determination of salbutamol residuals in pork samples. The method validation was performed using the LC-MS method.

Sequential injection analysis for the determination of fluoroquinolone antibacterial drug residues by using eosin Y as complexing agent

A sequential injection analysis (SIA) method was developed for the rapid and sensitive determination of fluoroquinolone residues, including norfloxacin, ciprofloxacin and enrofloxacin, in fish samples. The method is based on the reaction between fluoroquinolone drug and eosin Y in Britton-Robinson buffer (pH 2.0), forming pink colored complexs with maximum absorptions at 522, 525 and 527 nm for norfloxacin, ciprofloxacin and enrofloxacin, respectively. Linearity ranges were found to be 0.05-10.0 mg L^-1 (r² = 0.9996), 0.1-10.0 mg L^-1 (r² = 0.9995) and 0.05-10.0 mg L^-1 (r² = 0.9997) for norfloxacin, ciprofloxacin and enrofloxacin, respectively. The detection limit was found to be in the range of 0.013-0.019 mg L^-1. The method was tested and validated for various parameters according to main guidelines. The proposed SIA method was successfully applied for the determination of fluoroquinolone drug residues in fish samples with the sampling rate of 47 h^-1. The results demonstrated that the method is accurate, precise and reproducible, while being simple, rapid, economical and less time consuming. It can be suitably applied for the estimation of fluoroquinolone drug residues in routine quality control.