Dietary supplement mislabelling: case study on selected slimming products by developing a green isocratic HPLC method for their quality control.

Nowadays, a huge population consumes Dietary supplements for losing weight. Products are often claimed as botanical blends, yet they aren't necessarily safe. Misleading labels are also very common. Thus, validated analytical methods for a wide range of slimming compounds are highly needed. Herein, we present a simple HPLC/PDA method for the quantitation of seven popular slimming ingredients. Studied compounds were Caffeine, Raspberry Ketone, trans-Resveratrol, p-Synephrine, p-Octopamine, p-Hordenine and 2-phenethylamine. After optimization, separation was carried out on a C18 column and mobile phase was a mixture of Acetonitrile:Water containing 0.1% phosphoric acid (50:50, %v/v). The last compound was eluted at 9.76 min. Separation was efficient showing baseline- separated symmetric peaks, without using any gradient programs, organic mobile phase modifiers or modified stationary phases. Method validation was done following ICH guidelines. Calibration curves were linear over wide concentration ranges and calculated LOD values were in the range 0.02-0.09 µg/mL. Method greenness was assessed using Analytical Eco-scale, GAPI and AGREE metric tools. Further, four random sample products purchased from online supplement stores were assayed. Results proved some mislabeling actions. To support our findings, standard addition was carried out and average % recoveries were 96.67 - 101.44% with standard deviation ≤ 2.83 between measurements.

Quality control of dietary supplements: An economic green spectrofluorimetric assay of Raspberry ketone and its application to weight variation testing.

Although Dietary supplements are readily accessible and extensively used worldwide, they are inadequately regulated and consumers are victims of manufacturers' fraud. Thus, quality regulations are required to ensure safety of products available to the public. We propose the first native spectrofluorimetric quality control assay of raspberry ketone, a popular dietary supplement ingredient for weight loss. This work relies on the constant wavelength synchronous scan of the Raspberry Ketone native fluorescence, overcoming the demerits of conventional excitation/ emission spectra. For the best measurement conditions, several parameters were optimized including Δλ value, diluting solvent, medium pH and the effect of surfactants/ macromolecules. In aqueous medium (Δλ = 110 nm), a linear relationship exists between synchronous fluorescence intensity at peak maximum 405.6 nm and solution concentration in the range 300-1500 ng/mL. Method sensitivity was recorded with LOD and LOQ values 60.63 and 183.72 ng/mL; respectively. Validation was done in accordance to International Conference on Harmonization (ICH) guidelines. This simple procedure was successfully applied to the analysis of Raspberry Ketone in commercially available dietary supplement capsules with average recovery 98.67% ± 1.74 and further extended to weight variation testing following the official United States Pharmacopeial (USP) guidelines. Finally, green assessment was done using the ''Analytical Eco-scale'' tool. The total score was 89/100 points revealing excellent greenness of our proposal. Our proposal is simple, eco-friendly and cheap. It can be conveniently adopted for routine quality control practices especially in developing countries.

Graphene nanoplatelets in potentiometry: A nanocomposite carbon paste and PVC based membrane sensors for analysis of Vilazodone HCl in plasma and milk samples.

Graphene is the ''new star'' material for electrochemical sensing. It has unique mechanical, thermal and electrical properties, in addition to its ultra light weight. In the present work we combine for the first time the special features offered by graphene and the advantages of ion selective potentiometric sensors in a single study. We propose two types of sensors, a graphene based carbon paste and a poly vinyl chloride (PVC) based membrane sensors for the analysis of Vilazodone hydrochloride in bulk, human plasma and formula milk samples. Electro active agent is an ion- association complex based on coupling of Vilazodone cationic cite with anionic cite of Molybdate ion in a ratio 1:1. Both sensors are evaluated according to the IUPAC recommendation data, revealing linear response in the concentration range 10-7 - 10-3 and10-8 - 10-3 M with a Nernestian slope 59.89 and 59.91 mV/decade for PVC membrane and Carbon paste sensors, respectively. Both sensors were successfully applied to the analysis of Vilazodone HCl in human plasma and formula milk samples showing good recovery percentage values. Graphene based carbon paste sensor shows several advantages over conventional PVC membrane sensor regarding lower limit of detection, faster response time, longer life time and higher selectivity towards target ion.