Rapid and sensitive detection of etomidate based on functionalized copper nanoclusters fluorescent probe.

Etomidate as a non-barbiturate sedative, has central inhibitory effect and addiction and has been listed as a controlled drug in some countries due to the abusing trend nowadays. Therefore, rapid and sensitive detection of etomidate is of great significance. In this work, a novel fluorescent sensing probe (CuNCs@MIPs) based on copper nanoclusters (CuNCs) and molecular imprinted polymers (MIPs) has been firstly reported. CuNCs was environment-friendly synthesized using poly(vinylpyrrolidone) as a template and ascorbic acid as a reducing agent. After functionalized with molecular imprinting technique, the CuNCs@MIPs probe has special binding cavities on surface to target etomidate, causing the fluorescence intensity rapidly decrease, which confirmed it has excellent sensitivity, selectivity and stability. Under optimal conditions, the fluorescent sensing probe presented high precision linear relationship for etomidate in range of 10-500 ng/ml with detection limit of 10 ng/ml, and the whole detection process was completed within 10 min. This sensing method has also been applied to real samples detection, still demonstrated excellent feasibility in electronic cigarette liquids and urine. More importantly, compared with previous methods, this fluorescent sensing method has advantages such as rapid, simple and easy to operate. Collectively, the proposed CuNCs@MIPs sensing probe has good fluorescence characteristics and simple synthesis strategy, showed a great potential in etomidate detection and application.

A tailored ratiometric fluorescent sensor based on CdTe and MgF2 quantum dots for trace N-ethylpentylone detection.

The development of low-cost and highly sensitive ratiometric fluorescence sensor, CdTe@MIPs/MgF2, for N-Ethylpentylone (NEP) detection in wastewater samples is described. In this system, CdTe@MIPs (λex = 370, λem = 570) are employed as the receptor and response unit for NEP, with MgF2 (λex = 370, λem = 470) as the reference signal to enhance stability. Under optimal conditions, the sensor shows fluorescent quenching response at 570 nm to NEP in linear range of 2-200 nM, with LOD of 0.6 nM. The sensor also demonstrates significant selectivity for NEP over other analogues and interferents, making it ideal for practical applications in wastewater analysis. This approach is potentially more cost-effective and sensitive than conventional mass spectrometry in detecting abused substances in sewage. Additionally, the MgF2 fluorescent nano-material was first-ever developed and investigated, which may be significant in future research.

Trace detection of methcathinone in sewage using targeted extraction based on magnetic molecularly imprinted polymers coupled with liquid chromatography-tandem mass spectrometry.

Methcathinone, a new psychoactive substance (NPS), poses a serious threat to public health. Therefore, there is an urgent need to develop a reliable, selective, sensitive and simple analytical technique for monitoring trace amounts of this target NPS in complex matrices. For this purpose, magnetic molecularly imprinted polymers (MMIPs) based on MIPs combined with nano-sized magnetic Fe3O4 were developed for the specific enrichment of methcathinone in wastewater. The binding properties and selectivity of MMIPs toward methcathinone were evaluated and compared with non-imprinted polymer (MNIPs). For sensitive and selective extraction and determination of the target methcathinone, magnetic solid-phase extraction (MSPE) based on MMIPs was combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under optimized conditions, the proposed method was successfully used for the detection of methcathinone in wastewater, which provided a low limit of detection of 0.3 ng L-1 and a limit of quantification of 1.0 ng L-1 with relative standard deviations of less than 6.89% for intra- and inter-day analyses. Good linearity in the range of 1-2000 ng L-1 with a coefficient of determination (R2) greater than 0.98 was observed. Moreover, a certified reference material of water sample was successfully analyzed with satisfactory results and the recoveries of spike experiments ranged from 96.35-116.7%.