A disposable electrochemical immunosensor method was developed for ochratoxin A analysis to be applied for wine samples by using a screen-printed gold working electrode with carbon counter and silver/silver chloride pseudo-reference electrode. An indirect competitive enzyme-linked immunosorbent assay (ELISA) format was constructed by immobilising ochratoxin A conjugate using passive adsorption or covalent immobilisation via amine coupling to a carboxymethylated dextran (CMD) hydrogel on the gold working electrode. Electrochemical detection was performed using 3,3',5,5'tetramethylbenzidine dihyrochloride (TMB) and hydrogen peroxide with horse radish peroxidase (HRP) as the enzyme label. Chronoamperometry at-150 mV vs. onboard screen-printed Ag-AgCl pseudo-reference electrode was then used to detect the generated signal. The performance of the assay and the sensor was optimised and characterised in pure buffer conditions before applying to wine samples. The resulting immunosensor for ochratoxin A in buffer achieved a limit of detection of 0.5 μg L-1 with a linear dynamic detection range of 0.1-10 μg L-1 for passive adsorption of the toxin conjugate. While for covalent immobilisation through CMD-modified gold electrode, a limit of detection of 0.05 μg L-1 was achieved with a linear dynamic detection range of 0.01 µg L-1 to 100 µg L-1. The CMD-modified gold immunosensor was then evaluated in spiked and affinity purified wine samples achieving a detection limit comparable to buffer solutions (0.05 μg L-1).

An electrochemical affinity sensor for the determination of fumonisins mycotoxins (Fms) using monoclonal antibody modified screen-printed gold electrode with carbon counter and silver-silver chloride pseudo-reference electrode is reported in this work. A direct competitive enzyme-linked immunosorbent assay (ELISA) was initially developed, exhibiting a detection limit of 100 µg·L-1 for fumonisins. This was then transferred to the surface of a bare gold screen-printed electrode (SPGE) and detection was performed by chronoamperometry, monitoring the reaction of 3,3’,5,5’-Tetramethylbenzidine dihydrochloride (TMB) and hydrogen peroxide (H2O2) catalysed by HRP at −100 mV potential vs. onboard Ag-AgCl pseudo-reference electrode. The immunosensor exhibited detection limit of 5 µg·L−1 fumonisins with a dynamic range from 1 µg·L−1–1000 µg·L−1. The sensor also performed well in extracted corn samples.

A muffler is a device to attenuate noise from the exhaust. The muffler performance determined by the acoustic performance is called sound transmission loss (STL). This paper aims to measure the STL experimentally and correlated with the 1D simulation result. STL was measured using the impedance tube. Four-pole method (microphone) and two-load method were applied to measure the STL. The STL was also determined through the 1D simulation tools software. Three types of mufflers STL were measured; small expansion chamber, big expansion chamber and complex muffler. The respective error between simulation and experiment were 0.17%, 7.89%, and 11.40%. Hence, the STL experiment result was well correlated with the 1D simulation model.

No abstract