Polarographic determination of vitamin C after derivatization with o-phenylenediamine

Employing molecularly imprinted polymers in the development of electroanalytical methodologies for antibiotic determination

Antibiotics, although being amazing compounds, need to be monitored in the environment and foodstuff. This is primarily to prevent the development of antibiotic resistance that may make them ineffective. Unsurprisingly, advances in analyticalsciences that can improve their determination are appreciated. Electrochemical techniques are known for their simplicity, sensitivity, portability and low-cost; however, they are often not selective enough without recurring to a discriminating element like an antibody. Molecular imprinting technology aims to create artificial tissues mimicking antibodies named molecularly imprinted polymers (MIPs), these retain the advantages of selectivity but without the typical disadvantages of biological material, like limited shelf-life and high cost. This manuscript aims to review all analytical methodologies for antibiotics, using MIPs, where the detection technique is electrochemical, like differential pulse voltammetry (DPV), square-wave voltammetry (SWV) or electrochemical impedance spectroscopy (EIS). MIPs developed by electropolymerization (e-MIPs) were applied in about 60 publications and patents found in the bibliographic search, while MIPs developed by other polymerization techniques, like temperature assisted ("bulk") or photopolymerization, were limited to around 40. Published works covered the electroanalysis of a wide range of different antibiotics (β-lactams, tetracyclines, quinolones, macrolides, aminoglycosides, among other), in a wide range of matrices (food, environmental and biological).

Extraction and electrochemical detection of capsaicin and ascorbic acid from fresh chilli using ionic liquids

Capsaicin (flavour indicator) and ascorbic acid (vitamin C, freshness indicator) were simultaneously extracted from fresh chillies and quantified.

Application of gas-diffusion microextraction to solid samples using the chromatographic determination of α-diketones in bread as a case study

For the first time, gas-diffusion microextraction was used for the direct analysis of solid samples (vicinal diketones in bread).

Differential responses of the antioxidant defence system and ultrastructure in a salt-adapted potato cell line

Changes in lipid peroxidation and ion content and the possible involvement of the antioxidant system in salt tolerance at the cellular level was studied in a potato (Solanum tuberosum L.) callus line grown on 150 mM NaCl (salt-adapted) and in a non-adapted line exposed to 150 mM NaCl (salt-stressed). Salinity reduced the growth rate and increased lipid peroxidation in salt-stressed line, which remained unaltered in the adapted line. Na⁺ and Cl⁻ content increased due to salinity in both lines, but the adapted line displayed greater K⁺/Na⁺ ratio than the stressed one. Total superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) activities decreased in both salt-exposed lines; catalase (CAT, EC 1.11.1.6) activity did not change in the adapted line, but decreased in the stressed cell line. Salinity caused the suppression of one GR isoform, while the isozyme patterns of SOD, APX, and CAT were not affected. Ascorbate and reduced glutathione increased in both salt-exposed calli lines. α-Tocopherol increased as a result of salt exposure, with higher levels found in adapted calli. Electron microscopy showed that neither the structural integrity of the cells nor membrane structure were affected by salinity, but plastids from adapted cells had higher starch content. The results suggest that the enzymic and non-enzymic components of the antioxidant system are differentially modulated by salt. Different concentrations of antioxidant metabolites are more relevant to the adaptive response to salinity in potato calli than the differences in activity of the antioxidant enzymes.