Point-of-care electrochemical sensor for selective determination of date rape drug "ketamine" based on core-shell molecularly imprinted polymer.

Misuse of illicit drugs is a serious problem that became the primary concern for many authorities worldwide. Point-of-care (POC) diagnostic tools can provide accurate and fast screening information that helps to detect illicit drugs in a short time. A portable, disposable and reproducible core-shell molecularly imprinted polymer (MIP) screen-printed sensor was synthesized as a POC analyzer for the assay of the date rape drug "ketamine hydrochloride" in different matrices. Firstly, the screen-printed electrode substrate was modified electrochemically with polyaniline (PANI) as an ion-to-electron transducer interlayer to improve the potential signal stability. Secondly, core-shell MIP was prepared, the core consisting of silica nanoparticles prepared by Stober's method, while the MIP shell was synthesized onto silica nanoparticles surface by copolymerizing methacrylic acid functional monomer and the crossing agent; ethylene glycol dimethacrylate in the presence of ketamine as a template molecule. Finally, the core-shell MIP was incorporated into the PVC membrane as an ionophore and drop-casted over PANI modified screen-printed carbon electrode. The imprinting process and the morphology of MIP were examined using scanning electron microscopy, Fourier-transform infrared and X-ray photoelectron spectroscopic methods. The sensor exhibited a short response time within 3-5 s in a pH range (2.0-5.0). The potential profile indicated a linear relationship in a dynamic concentration range of 1.0 × 10-6 M to 1.0 × 10-2 M with a slope of 54.7 mV/decade. The sensor was employed to determine ketamine in biological matrices and beverages.

Experimentally designed chemometric models for the assay of toxic adulterants in turmeric powder.

Turmeric is an indispensable culinary spice in different cultures and a principal component in traditional remedies. Toxic metanil yellow (MY), acid orange 7 (AO) and lead chromate (LCM) are deliberately added to adulterate turmeric powder. This work compares the ability of multivariate chemometric models with those of artificial intelligent networks to enhance the selectivity of spectral data for the rapid assay of these three adulterants in turmeric powder. Using a custom experimental design, we provide a data-driven optimization for the sensitive parameters of the partial least squares model (PLS), artificial neural network (ANN) and genetic algorithm (GA). The optimized models are validated using sets of genuine turmeric samples from five different geographical regions spiked with standard adulterant concentrations. The optimized GA-PLS and GA-ANN models reduce the root mean square error of prediction by 18.4%, 31.1% and 55.3% and 25.0%, 69.9% and 88.4% for MY, AO and LCM, respectively.

Simultaneous spectrophotometric determination of compounds having relatively disparate absorbance and concentration ranges; application to antidiabetic formulation of linagliptin and metformin.

The limited linear range of UV-Visible spectrophotometry may be insufficient to occupy multiple components with wide variations in their concentrations or absorptivities that will hinder the simultaneous spectrophotometric determination and may require spiking or measurements in subsequent dilution steps. The current work introduces the absorptivity target concentration (ATC) values, a simple way for the proper choice of the working spectral region to execute accurate and linear spectrophotometric measurements. Simultaneous spectrophotometric determination of linagliptin (LNG) and metformin (MET) that are present in a ratio of 1:400 was carried out using traditional spectrophotometric techniques such as third derivative and derivative ratio as well as recently developed techniques such as ratio difference and factorized dual wavelength. The proposed methods were able to determine MET in the concentration range of 50-1200 µg mL-1. On the other hand, LNG was successfully determined from its zero-order absorption UV-spectrum at λmax (296 nm) in the concentration range 2.5-25 µg mL-1. The mentioned methods were successfully applied for the determination of the LNG and MET in their combined dosage form. The methods were validated according to the ICH guidelines. The proposed ATC value can be employed as a novel concept for the proper choice of the working spectral region where spectrophotometric measurements can be deployed accurately and precisely.