Investigation of chemical modifiers for the determination of cadmium and chromium in fish oil and lipoid matrices using HR-CS GF AAS and a simple ‘dilute-and-shoot’ approach

Chromium speciation by the combination of high-performance liquid chromatography and inductively coupled plasma-optical emission spectrometry

A hyphenated instrumental method high-performance liquid chromatography-inductively coupled plasma-optical emission spectrometry (HPLC-ICP-OES) was used for the separation and determination of Cr(III) and Cr(VI). After the chromatographic separation of chromium species by anion exchange column, their spectrophotometric detection was carried out by ICP-OES system. Important instrumental and chromatographic parameters were investigated via univariate optimization approach to obtain high signal to noise ratio and good resolution for chromium species. Under the optimum HPLC-ICP-OES conditions, limit of detection (LOD) values for Cr(III) and Cr(VI) were found to be 0.27 and 0.05 mg/kg, respectively. In addition, accuracy and applicability of developed method were checked by recovery experiments performed with the spiked soil, grass, and water samples. High percent recovery results (88-104%) were achieved by utilizing matrix matching calibration strategy for the selected samples. The results showed that this method was accurate and applicable to soil, grass, and water samples.

A new and facile nanosilver SPR colored method for ultratrace arsenic based on aptamer regulation of Au-doped carbon dot catalytic amplification

Here, Au-doped carbon dots (CD_Au) nanosols with good stability were prepared by hydrothermal reaction method. We found that CD_Au can efficiently catalyze the nanoreaction of reducing AgNO₃ by glucose, and at 420 nm，the reaction products of yellow spherical silver nanosol exhibit an intense surface plasmon resonance (SPR) absorption peak. The nucleic acid aptamers (Apt) can be adsorbed on the surface of carbon dots, so that their catalytic activity was suppressed, the nanosilvers were reduced, the solution color becomes lighter, and the Abs value was weakened. When As³⁺ was added, it forms a stable conjugate with the Apt, releases free carbon dots, restored its catalytic activity, and the color and Abs signals enhanced linearly. Based on the Apt regulation and the catalytic amplification effect of CD_Au on AgNO₃-glucose, a new extremely sensitive SPR spectrophotometric method for the determination of arsenic ion content of 0.025-0.75 μg/L was established, and the detection limit of As³⁺ is 0.01 μg/L.