Etching of thick copper foil masked except for a single rectangular opening having an aspect ratio (width:depth) of 5:1 or 1:1 was investigated in the presence of controlled laminar flow across the width of the pattern opening. In a solution of , copper was found to form a surface film spontaneously at the “corrosion potential,” to dissolve at a rate that depended upon convective mass‐transfer conditions, and also to exhibit anisotropic wet chemical etching. Based on thermodynamic calculations, it was estimated that the dominant cupric species were Cu⁺², , , and , and that the dominant cuprous species was . Based on rotating disk measurements it was concluded that anisotropic chemical etching was related to the presence of a sparingly soluble surface film of . Under operating conditions for which anisotropic etching was observed, current transients were found to exhibit a characteristic “overshoot” response that may represent a useful diagnostic signal for process control.

Aflatoxins are highly toxic fungal secondary metabolites that often contaminate food and feed commodities. An electrochemical immunosensor for the determination of aflatoxin B₁ (AFB₁) was fabricated by immobilizing monoclonal AFB₁ antibodies onto a screen-printed gold electrode that was modified with carbo-methyldextran by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide cross-linking. An electrochemical interfacial modelling of biomolecular recognition was suggested and reasonably interpreted. Impedance technology was employed for the quantitative determination of AFB₁. The limit of detection concentration of AFB₁ for standard solutions and spiked pistachio samples was 0.5 ng/mL and 1 ng/mL, respectively. The immunosensor was able to successfully determine AFB₁ concentrations in the range of 4.56–50.86 ng/mL in unknown pistachio samples. Comparative chromatographic analysis revealed that AFB₁ concentrations that were higher than 345 ng/mL were not within the immunosensor’s upper limits of detection. Selectivity studies against Ochratoxin A and Aflatoxin M₁ demonstrated that the proposed AFB₁ immunosensor was able to differentiate between these other fungal mycotoxins. The novel electrochemical immunosensor approach has the potential for rapid sample screening in a portable, disposable format, thus contributing to the requirement for effective prevention and the control of aflatoxin B₁ in pistachios.

The potential of X-ray imaging for detecting pistachios with kernel necrotic (KN) spots was the main objective of this study. X-ray images of whole pistachios were compared with colour pictures of the same nuts taken after the kernel was opened by splitting it in two. The necrotic spots appear in the X-ray images as darker gray areas of almost round shape. Also, pistachios with KN spots contained about 60 times more aflatoxin than healthy ones in an aflatoxin contaminated sample. Elimination of such nuts will reduce aflatoxin in contaminated batches and improve the quality in batches free of aflatoxin.