Detection of trace metal ions in high-purity boric acid by online two-dimensional valve switching coupled with ion chromatography-inductively coupled plasma mass spectrometry

Ultra-sensitive detection and scavenging of arsenic ions and ciprofloxacin using 3D multipurpose hemicellulose based aerogel: Adsorption mechanism and RSM optimization

Trace level detection and efficient removal of arsenite ions (As (III)) and ciprofloxacin (CPR) antibiotic was achieved using hemicellulose based ratiometric fluorescent aerogel. Hemicellulose derived from rice straw was oxidised to dialdehyde hemicellulose followed by crosslinking using chitosan via a Schiff base reaction (C = N) yielding a highly porous 3D fluorescent aerogel (CS@DAHCA). Various factors governing adsorption were analyzed by applying response surface methodology (RSM) approach. CS@DAHCA exhibited ultra-trace level monitoring with the limit of detection of 3.529 pM and 55.2 nM for As (III) and CPR, respectively. The CS@DAHCA showed maximum adsorption capacity of 185 μg g-1 and 454 mg g-1 for As (III) and CPR, respectively. Finally, the feasibility of CS@DAHCA was ascertained for real water samples confirming it as promising candidate for remediation of As (III) and CPR.

Automated and semi-automated packed sorbent solid phase (micro) extraction methods for extraction of organic and inorganic pollutants

In this study, the packed sorbent solid phase (micro) extraction methods from manual to automated modes are reviewed. The automatic methods have several remarkable advantages such as high sample throughput, reproducibility, sensitivity, and extraction efficiency. These methods include solid-phase extraction, pipette tip micro-solid phase extraction, microextraction by packed sorbent, in-tip solid phase microextraction, in-tube solid phase microextraction, lab-on-a-chip, and lab-on-a-valve. The recent application of these methods for the extraction of organic and inorganic compounds are discussed. Also, the combination of novel technologies (3D printing and robotic platforms) with the (semi)automated methods are investigated as the future trend.

Bright Mn-doped carbon dots for the determination of permanganate and L-ascorbic acid by a fluorescence on-off-on strategy

A one-pot hydrothermal synthesis of manganese-doped carbon dots (Mn-CDs) is reported for fluorescent "on-off-on" determination of Mn(VII) and L-ascorbic acid (L-AA) in aqueous solution and living cells. Mn-CDs were prepared by using sulfanilic acid, tetrakis(hydroxymethyl)phosphonium chloride, and Mn(II) chloride as precursors. Mn-CDs were characterized by several spectroscopic methods and microscopic techniques. Mn-CDs show distinctly long fluorescence lifetime (12.39 ± 0.07 ns) and high absolute fluorescence quantum yield (around 37%) with excitation and emission wavelengths of 362 and 500 nm, respectively. Mn-CDs exhibit no significant cytotoxicity to human cervical carcinoma HeLa cells and human embryonic kidney HEK-293T cells at 200 μg mL^-1 level after 48 h incubation. The fluorescence of Mn-CDs at 500 nm (excited at 362 nm) is quenched efficiently by Mn(VII) and can be further recovered after the addition of L-AA, resulting in a fluorescent "on-off-on" assay for the determination of Mn(VII) and L-AA. Under optimal experimental conditions, the linear response covers the 3 to 150 μM Mn(VII) concentration range and the 3 to 140 μM L-AA concentration range. This method offers relatively low detection limits of 0.66 μM for Mn(VII) and 0.90 μM for L-AA. This strategy was applied to visual determination of Mn(VII) and L-AA in living HeLa cells with satisfying results. Graphical abstract Schematic presentation of bright Mn-CD-based fluorescence "on-off-on" assay for both Mn(VII) and L-AA. This fluorescent assay possessed low detection limit of 0.66 μM for Mn(VII) and 0.90 μM for L-AA. This strategy was applied for visual determination of Mn(VII) and L-AA in living HeLa cells with satisfying results.

Highly sensitive detection of cobalt through fluorescence changes in β-cyclodextrin-bimane complexes

A supramolecular complex of syn-(methyl,methyl)bimane (1) and β-cyclodextrin demonstrates a sensitive (limit of detection = 0.60 nM) and selective fluorescence turn-off response in the presence of cobalt in aqueous media, with calibration curves enabling quantitation in solution and using filter papers on which bimane and cyclodextrin were adsorbed. 1H NMR spectroscopy provides insight into interactions underlying the sensor performance.