Stir bar sorptive extraction of diclofenac from liquid formulations: A proof of concept study

Porphyrin-functionalized graphene oxide sheets: An efficient nanomaterial for micro solid phase extraction of non-steroidal anti-inflammatory drugs from urine samples

In this work, porphyrin-functionalized graphene oxide nanosheets (GO@meso-tetrakis(4-hydroxyphenyl)porphyrin) were synthesized and employed as the sorbent. Porphyrins owing to their unique structures and tunable terminal functional groups are expected to be promising media for extraction of the desired analytes. Also, GO with a high specific surface area has exhibited good potential for the extraction purposes. Inspired by these intriguing properties, the combination of GO and porphyrin can benefit both of these amazing features. The synthesized sorbent was utilized for micro solid phase extraction of non-steroidal anti-inflammatory drugs followed by HPLC-UV. Optimization of the experimental factors including sorbent amount, sample pH, sample and eluent flowrates, eluent volume, and the number of desorption cycles were performed with the aid of central composite design. Under the optimal conditions, the calibration curves were linear within the range of 2.0-600 ng mL^-1 and limits of detection were found between 0.5-2.0 ng mL^-1. The preconcentration factors and absolute recoveries were obtained in the range of 4.80-9.79 and 29%-59%, respectively. The matrix effect for the urine samples varied between 81.9%-91.6% at two concentrations of 50 and 300 ng mL^-1, respectively. Intra- and inter-day RSD% (n = 3) of the spiked urine samples at three level concentrations of 25, 100, and 300 ng mL^-1 were less than 10%. The relative recoveries of the urine samples were calculated in the range of 85.2-98.6%. Eventually, the method exhibits proper sensitivity, excellent repeatability, high reusability, and acceptable precision and accuracy.

Analysis of diclofenac in water samples using in situ derivatization-vortex-assisted liquid-liquid microextraction with gas chromatography-mass spectrometry

A novel micro-extraction technique for a rapid and sensitive analysis of diclofenac (DCF) in water samples has been developed. DCF was derivatized and extracted simultaneously using vortex-assisted liquid-liquid micro-extraction (VALLME) prior to gas chromatography with mass spectrometry detection. The effects of extraction solvent volume, extraction and derivatization time and ionic strength of the sample were studied using 23 factorial experimental design. The optimum extraction conditions were as follows: 200 μL of chloroform, 25 μL of N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatization reagent, vortex extraction and derivatization time 5 min at 3000 rpm. The extraction recovery for different fortification levels was 98 %. Also, the proposed micro-extraction method exhibited results comparable with the solid phase extraction of real water samples. The proposed one-step VALLME and derivatization method is simpler and faster than the conventional extraction and derivatization methods used for the determination of DCF in real water samples.

Determination of diclofenac sodium by resonance light scattering method using silver nanoparticles as probe

A sensitive, simple and novel method was developed to determine diclofenac sodium (DS) using silver nanoparticles (AgNPs) as probe by resonance light scattering (RLS) technique. It was found that DS could quench the RLS intensity of AgNPs. Moreover, the decrease in RLS intensity was linearly correlated to the concentration of DS over the range of 0.01-2.0μgmL^-1. DS can be measured in a short time (5min) without any complicated or time-consuming sample pretreatment process. Parameters that affect the RLS intensities such as pH, concentration of AgNPs, reaction time, electrolyte concentration, and coexisting substances were systematically investigated and optimized. The results showed that the method had a very good selectivity and could be used conveniently for the determination of DS. The limit of detection (LOD) was 2.85ngmL^-1 (3σ), and the relative standard deviation (RSD) was less than 3.6% (n=6). Possible mechanism for the RLS changes of AgNPs in the presence of DS was discussed and the method was successfully applied for the analysis of tablets and urine samples.

A comprehensive strategy in the development of a cyclodextrin-modified microemulsion electrokinetic chromatographic method for the assay of diclofenac and its impurities: Mixture-process variable experiments and quality by design

A comprehensive strategy involving the use of mixture-process variable (MPV) approach and Quality by Design principles has been applied in the development of a capillary electrophoresis method for the simultaneous determination of the anti-inflammatory drug diclofenac and its five related substances. The selected operative mode consisted in microemulsion electrokinetic chromatography with the addition of methyl-β-cyclodextrin. The critical process parameters included both the mixture components (MCs) of the microemulsion and the process variables (PVs). The MPV approach allowed the simultaneous investigation of the effects of MCs and PVs on the critical resolution between diclofenac and its 2-deschloro-2-bromo analogue and on analysis time. MPV experiments were used both in the screening phase and in the Response Surface Methodology, making it possible to draw MCs and PVs contour plots and to find important interactions between MCs and PVs. Robustness testing was carried out by MPV experiments and validation was performed following International Conference on Harmonisation guidelines. The method was applied to a real sample of diclofenac gastro-resistant tablets.

Innovative sampling and extraction methods for the determination of nonsteroidal anti-inflammatory drugs in water

Two different innovative approaches were used for the determination of nonsteroidal anti-inflammatory drugs (NSAIDs) in water: stir bar sorptive extraction (SBSE) and passive sampling, followed by electrospray ionization liquid chromatography-tandem mass spectrometry. SBSE was developed by comparing EG-Silicone and PDMS stir bars and optimizing main parameters to attain high preconcentration. Quantitative analysis was carried out by mass spectrometry in negative ionization mode and multiple reaction monitoring. The SBSE-LC-MS/MS method provided satisfactory figures of merit with LOD (7.5-71 ng L(-1)) and LOQ (22.5-213 ng L(-1)). The developed method was successfully applied to real samples collected from river water and wastewater effluents. The obtained results showed the presence of all analytes at trace levels, in a wide range of concentrations. The passive sampling approach was carried out by using Polar Organic Chemical Integrative Sampler (POCIS); samplers were deployed for 15 days in river and tap water, allowing to detect analytes at ultra-trace levels. Time-Weighted Average concentration of NSAIDs in river water was estimated in the range 0.33-0.46 ng L(-1), using the sampling rates previously obtained by means of a simple calibration system.

Stir bar sorptive extraction: recent applications, limitations and future trends

Stir bar sorptive extraction (SBSE) has generated growing interest due to its high effectiveness for the extraction of non-polar and medium-polarity compounds from liquid samples or liquid extracts. In particular, in recent years, a large amount of new analytical applications of SBSE has been proposed for the extraction of natural compounds, pollutants and other organic compounds in foods, biological samples, environmental matrices and pharmaceutical products. The present review summarizes and discusses the theory behind SBSE and the most recent developments concerning its effectiveness. In addition, the main results of recent analytical approaches and their applications, published in the last three years, are described. The advantages, limitations and disadvantages of SBSE are described and an overview of future trends and novel extraction sorbents and supports is given.