Screen-printed sensor for batch and flow injection potentiometric chromium(VI) monitoring

A novel CaO nanocomposite cross linked graphene oxide for Cr(VI) removal and sensing from wastewater

A novel green nanocomposite has been prepared by immobilizing CaO nanoparticles (CaO NPs) on the surface of graphene oxide. Biogenic CaO-NPs were synthesized from Lala clamshells. Morphological and structural characterizations of the nanocomposite were studied extensively. The adsorption capacity (q_max) of the nanocomposite for removing Cr(VI) was 38.04 mg g^-1. In addition to this, the adsorption data were adequately simulated with Langmuir, Freundlich, Temkin, and pseudo-second-order models, suggesting that the adsorption process was the combination of external mass transfer and chemisorption. Electrostatic interaction was the dominant mechanism for Cr(VI) removal. In addition, the synthesized nanocomposites also serve as an excellent sensor for Cr(VI) sensing, with a limit of detection (LOD) of 0.02 μM utilizing electrochemical methods. Therefore, this green nanocomposite can simultaneously serve as an adsorbent and sensor for Cr(VI)removal from aqueous solutions.

Fluorometric sensing of Pb2+and CrO42−ions through host–guest inclusion for human lung cancer live cell imaging

The formation of an inclusion complex between 1,5-dihydroxyanthraquinone (1,5-DHAQ;1) and β-cyclodextrin (β-CD) in aqueous media has been studied by UV-visible and fluorescence spectroscopy.

Ratiometric detection of Cr3+ and Hg2+ by a naphthalimide-rhodamine based fluorescent probe

Newly synthesized rhodamine derivatives, L(1) and L(2), are found to bind specifically to Hg(2+) or Cr(3+) in presence of large excess of other competing ions with associated changes in their optical and fluorescence spectral behavior. These spectral changes are significant enough in the visible region of the spectrum and thus, allow the visual detection. For L(1), the detection limit is even lower than the permissible [Cr(3+)] or [Hg(2+)] in drinking water as per standard U.S. EPA norms; while the receptor, L2 could be used as a ratiometric sensor for detection of Cr(3+) and Hg(2+) based on the resonance energy transfer (RET) process involving the donor naphthalimide and the acceptor Cr(3+)/Hg(2+)-bound xanthene fragment. Studies reveal that these two reagents could be used for recognition and sensing of Hg(2+)/Cr(3+). Further, confocal laser microscopic studies confirmed that the reagent L(2) could also be used as an imaging probe for detection of uptake of these ions in A431 cells.

Septonex-tetraphenylborate screen-printed ion selective electrode for the potentiometric determination of Septonex in pharmaceutical preparations

A screen-printed electrode (SPE) was fabricated for the determination of 1-(ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex) based on the use of Septonex-tetraphenylborate as the electroactive substance, and o-nitrophenyloctylether (o-NPOE) as the plasticizing agent. The electrode passes a near-Nernstian cationic slope of 59.33 ± 0.85 mV from activity between pH values of 2 to 9 with a lower detection limit of 9×10(-7) M and response time of about 5 s and exhibits an adequate shelf-life of 6 months. The method was applied for the determination of Septonex in pharmaceutical preparations. A percentage recovery of 99.88% was obtained with RSD=1.24%. The electrode was successfully applied in the determination of Septonex in laboratory-prepared samples by direct potentiometric, calibration curve and standard addition methods. Potentiometric titration of Septonex with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the modified screen-printed electrode as an end-point indicator electrode. Selectivity coefficients for Septonex relative to a number of potential interfering substances were determined. The sensor was highly selective for Septonex over a large number of compounds. Selectivity coefficient data for some common ions show negligible interference; however, cetyltrimethylammonium bromide and iodide ions interfere significantly. The analytical usefulness of the proposed electrode was evaluated by its application in the determination of Septonex in laboratory-prepared pharmaceutical samples with satisfactory results. The results obtained with the fabricated sensor are comparable with those obtained by the British Pharmacopeia method.