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The use of amperometric biosensor for the detection of glyphosate herbicide and its metabolite aminomethylphosphonic acid (AMPA) is presented. The biosensor was developed by electrochemically depositing poly(2,5-dimethoxyaniline) (PDMA) doped with poly(4-styrenesulfonic acid) (PSS) onto the surface of a gold electrode followed by electrostatic attachment of horseradish peroxidase (HRP) onto the PDMA-PSS nanocomposite film. The PDMA-PSS film was characterized by transmission electron microscopy (TEM) and Fourier Transform infrared (FTIR) spectroscopy. The HRP immobilized on the PDMA-PSS film catalyzed the reduction of hydrogen peroxide, the inhibition of which was applied in the detection of glyphosate and AMPA. The limits of detection of the biosensor for glyphosate and AMPA were 0.16 mg L À1 and 1.0 mg L À1, respectively. The study demonstrates that the biosensor is very sensitive and could be a useful tool in the screening of glyphosate and AMPA at low concentrations.

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Since the outbreak of the Coronavirus Disease 2019 (CoViD-19), the World Health Organization has recommended that, in absence of soap and water, alcohol-based hand sanitizer can be used to prevent the transmission of coronaviruses. Unfortunately, many media and anecdotal reports indicate that many alcohol-based hand sanitizers sold in South Africa are substandard and some contain potentially toxic ingredients. The study aimed to identify hand sanitizers used in the Johannesburg area during the CoViD-19 pandemic that do not contain the recommended alcohol concentration of at least 70% propanol or 60% ethanol, and contain traces of toxic ingredients. Hand sanitizers randomly collected from various traders around Johannesburg were analyzed using Agilent auto sampler coupled to a gas chromatograph utilizing flame ionisation detection. Of the 94 hand sanitizer samples collected, three preparations contained no alcohol, whereas the rest contained either ethanol, 2-propanol or 1-propanol or a combination of two alcohols. Of the alcohol-containing hand sanitizers, 37 (41%) contained less than 60% alcohol. Ethyl acetate, isobutanol and other non-recommended alcohols (methanol and 3-methyl-butanol) were also identified. Consumers are therefore warned that among the many brands of hand sanitizers found around Johannesburg, there are some substandard preparations and some that contain traces of toxic ingredients.

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