Flow injection amperometric determination of hydrazine based on its electrocatalytic oxidation at pyrocatechol violet modified pencil graphite electrode

Naked-eye and fluorescence resonance energy transfer based ratiometric fluorescent probe for rapid, sensitive and selective detection of hydrazine and its applications in imaging of environmental samples and living systems

Hydrazine, a compound recognized for its carcinogenic and genotoxic properties, presents a significant threat to human health via environmental exposure and drug metabolism. The detection of hydrazine is essential for safeguarding human health. However, a tool capable of accurately detecting hydrazine across diverse sample types, such as soil, water sources, and plant specimens contaminated by hydrazine leakage, as well as cells and live mice containing endogenously generated hydrazine from drug metabolism, is still lacking. In this study, we have designed and synthesized a ratiometric fluorescent probe utilizing the fluorescence resonance energy transfer mechanism. Upon exposure to hydrazine, the probe exhibits an increased fluorescence ratio (F485 nm/F650 nm) accompanied by a color change from orange to light blue-green. The fluorescence sensing mechanism has been validated through high resolution mass spectrometer and density functional theory. This probe demonstrates significant potential for practical applications in detecting hydrazine within water and soil samples, as well as for imaging exogenous and drug-metabolized endogenous hydrazine in cellular and murine models.

Highly sensitive voltammetric determination of the fungicide fenhexamid using a cost-effective and disposable pencil graphite electrode

A differential pulse voltammetric (DPV) method is proposed for the highly sensitive determination of fenhexamid (FHX) based on both electrooxidation and electroreduction processes using a disposable and cost-effective pencil graphite electrode (PGE). The electrochemical oxidation and reduction mechanisms of FHX at the PGE were elucidated by recording cyclic voltammograms at various pH values of Britton-Robinson buffer (BRB) solutions at a scan rate of 50 mV s-1 and different scan rate values in the range 10-400 mV s-1 at selected pH of BRB (pH 2.0). Differential pulse voltammograms recorded under optimized conditions revealed an oxidation peak of FHX around + 0.65 V and a reduction peak of FHX around + 0.45 V. The DPV analysis of FHX revealed two linear ranges: 0.001-0.01 µmol L-1 and 0.01-5.0 µmol L-1 for the anodic peak, and 0.001-0.1 µmol L-1 and 0.1-5.0 µmol L-1 for the cathodic peak. The limits of detection were 0.34 nmol L-1 and 0.32 nmol L-1 for the anodic and cathodic peaks, respectively. The proposed methodology demonstrated satisfactory selectivity, as selected pesticides, certain electroactive compounds, and cationic species tested did not interfere with the voltammetric determination of FHX, particularly during its reduction. The recovery results, showing values close to 100% obtained from the analysis of real samples spiked with FHX, indicated that this methodology can accurately determine FHX in water and soil samples.

Electrochemical Sensors Based on a Composite of Electrochemically Reduced Graphene Oxide and PEDOT:PSS for Hydrazine Detection

In this study, hydrazine sensors were developed from a composite of electrochemically reduced graphene oxide (ErGO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), deposited onto a glassy carbon electrode (GCE). The structural properties, electrochemical characterization, and surface morphologies of this hydrazine sensor were characterized by Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). In addition, the proposed hydrazine sensor also demonstrates good electrochemical and analytical performance when investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometry techniques under optimal parameters. Using these investigated parameters, DPV and amperometry were chosen as techniques for hydrazine measurements and showed a linear range of concentration in the range of 0.2-100 μM. The obtained limits of detection and limits of quantitation for hydrazine measurements were 0.01 and 0.03 μM, respectively. In addition, the proposed sensor demonstrated good reproducibility and stability in hydrazine measurements in eight consecutive days. This fabricated hydrazine sensor also exhibited good selectivity against interference from Mg²⁺, K⁺, Zn²⁺, Fe²⁺, Na⁺, NO₂ ^-, CH₃COO^-, SO₄ ^2-, Cl^-, ascorbic acid, chlorophenol, and triclosan and combined interferences, as well as it depicted %RSD values of less than 5%. In conclusion, this proposed sensor based on GCE modified with ErGO/PEDOT:PSS displays exceptional electrochemical performance for use in hydrazine measurements and have the potential to be employed in practical applications.

A novel colorimetric and ratiometric fluorescence probe based on 'C-CN' for detection of hydrazine and its imaging in living cells and mouse

Hydrazine plays an important role in chemistry, pharmaceuticals, agriculture and aerospace. However, it is not to be underestimated and has been identified as harmful to the human body. Therefore, it is significant and urgent to develop the detection of hydrazine in vivo and in vitro. Here, the probe TAN was synthesized by using benzothiazole derivatives as the fluorophore and 2,3-diaminomaleonitrile as the identified group to detect hydrazine. The presence of hydrazine resulted in a colorimetric and ratiometric fluorescence response of the probe based on the formation of hydrazone. The detection limit of TAN was 0.31 µM for hydrazine. In addition, the probe TAN was successfully used to visualize hydrazine in living HepG-2 cells and mouse with low cytotoxicity and excellent biocompatibility.

Recent developments in electrochemical sensors for detecting hydrazine with different modified electrodes

The detection of hydrazine (HZ) is an important application in analytical chemistry. There have been recent advancements in using electrochemical detection for HZ. Electrochemical detection for HZ offers many advantages, e.g., high sensitivity, selectivity, speed, low investment and running cost, and low laboriousness. In addition, these methods are robust, reproducible, user-friendly, and compatible with the concept of green analytical chemistry. This review is devoted to the critical comparison of electrochemical sensors and measuring protocols used for the voltammetric and amperometric detection of the most frequently used HZ in water resources with desirable recovery. Attention is focused on the working electrode and its possible modification which is crucial for further development.

Micelles Mediated Zone Fluidics Method for Hydrazine Determination in Environmental Samples

An automated flow method for the determination of hydrazine based on the concept of zone-fluidics has been developed. The analyte reacts under flow conditions with p-dimethylamino benzaldehyde (25 mmol L-1) in micellar medium (100 mmol L-1 SDS) to form a stable derivative (460 nm). Micelles mediated catalysis excludes the use of highly acidic environment typical for this kind of reaction. Following careful examination of chemical and instrumental variables, the method allows the determination of hydrazine at the low micromolar level (0.3-10 μmol L-1) in water samples. Real sample analyses (drinking and boiler feed water) resulted in satisfactory results in terms of accuracy with the percent recoveries being in the range of 82-114%.