A solid bar microextraction method for the liquid chromatographic determination of trace diclofenac, ibuprofen and carbamazepine in river water

Diuretics in Different Samples: Update on the Pretreatment and Analysis Techniques

Diuretics are drugs that promote the excretion of water and electrolytes in the body and produce diuretic effects. Clinically, they are often used in the treatment of edema caused by various reasons and hypertension. In sports, diuretics are banned by the World Anti-Doping Agency (WADA). Therefore, in order to monitor blood drug concentration, identify drug quality and maintain the fairness of sports competition, accurate, rapid, highly selective and sensitive detection methods are essential. This review provides a comprehensive summary of the pretreatment and detection of diuretics in various samples since 2015. Commonly used techniques to extract diuretics include liquid-liquid extraction, liquid-phase microextraction, solid-phase extraction, solid-phase microextraction, among others. Determination methods include methods based on liquid chromatography, fluorescent spectroscopy, electrochemical sensor method, capillary electrophoresis and so on. The advantages and disadvantages of various pretreatment and analytical techniques are elaborated. In addition, future development prospects of these techniques are discussed.

Solvent bar microextraction combined with HPLC-DAD for simultaneous determination of diuretics in human urine and plasma samples

BACKGROUND

A simple and powerful microextraction procedure, the solvent bar microextraction (SBME), was used for the simultaneous determination of two diuretics, furosemide and spironolactone in human urine and plasma samples, using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD).

METHODS

The appropriate amount (2 µL) of 1-octanol as an organic solvent confined within (2.5 cm) of a porous hollow fiber micro-tube, sealed at both ends was used for this procedure. The conditions for the SBME were optimized in water and the analytical performance were examined in spiked human urine and plasma samples.

RESULTS

The optimized method exhibited good linearity (R2 > 0.997) over the studied range of higher than 33 to 104 µg L-1 for furosemide and spironolactone in urine and plasma samples, illustrating a satisfactory precision level with RSD values between 2.1% and 9.1%.

DISCUSSION

The values of the limits of detection were found to be in the range of 6.39 to 9.67 µg L-1, and extraction recovery˃ 58.8% for both diuretics in urine and plasma samples. The applicability and effectiveness of the proposed method for the determination of furosemide and spironolactone in patient urine samples were tested.

CONCLUSION

In comparison with reference methods, the attained results demonstrated that SBME combined with HPLC-DAD was proved to be simple, inexpensive, and promising analytical technology for the simultaneous determination of furosemide and spironolactone in urine and plasma samples.

A banana peel/silicon glue coated stir bar for extraction of aspirin, diclofenac, ibuprofen and mefenamic acid followed by high performance liquid chromatography-UV detection

In the current study, a green, cost-effective, and bio-degradable additive was used for the preparation of a highly efficient sorbent based on silicon glue. Here, a banana peel was pretreated and mixed with silicon glue. It was proved that the prepared banana peel-silicon glue bar is a reliable sorbent for stir bar sorptive extraction of nonsteroidal anti-inflammatory drugs (NSAIDs) including aspirin, diclofenac, ibuprofen and mefenamic acid in human urine and plasma. Compared to the lab-made sorbents, the prepared sorbent showed high extraction performance, high stability, and satisfactory reproducibility and involved easy preparation. In order to optimize the effective factors, different parameters such as (stirring rate, pH, extraction time, desorption time and elution solvent volume) were optimized using response surface methodology (RSM) through applying Central-Composite Design (CCD). Under the optimum conditions, the linear dynamic ranges of the target analytes were investigated in the range of 0.2-200 μg L^-1 with r² higher than 0.9929. Limits of detection (LODs) and limits of quantification (LOQs) of analytes were in the ranges of 0.04-0.5 and 0.15-1.65, respectively. The reproducibility of the method was also investigated by calculating the relative standard deviation. The RSD was measured to be lower than 4.9%. Bar-to-bar reproducibility at a 100 μg L^-1 concentration level was also evaluated to be lower than 5.3% (n = 3). Also, each prepared film can be used up to 64 times without any reduction in extraction performance. Finally, the method was successfully applied for the determination of selected drugs in different biological fluids including urine and plasma samples. The calculated relative recovery in real sample analysis was higher than 90%.

Carbon-Based Sorbent Coatings for the Determination of Pharmaceutical Compounds by Bar Adsorptive Microextraction

Thirteen carbon materials comprising commercial activated carbons and lab-made materials (activated carbons, hydrochars, and low-T and high-T activated hydrochars) were assayed as sorbent coatings in bar adsorptive microextration (BAμE) to monitor trace levels of ten common pharmaceutical compounds (PhCs) in environmental water matrices including surface water, seawater, tap water, and wastewater. Polar and nonpolar pharmaceuticals were selected, sulfamethoxazole, triclosan, carbamazepine, diclofenac, mefenamic acid, 17-α-ethinylestradiol, 17-β-estradiol, estrone, gemfibrozil, and clofibric acid, as model compounds to cover distinct therapeutic classes. Despite having a less-developed porosity, data showed that "in-house" prepared low-T activated hydrochars, obtained from carbohydrates and an eutectic salt mixture at low temperature (i.e., 180 °C) and autogenerated pressure, compete with the best commercial activated carbons for this particular application. The combination of a micro and mesopore network with a rich oxygen-based surface chemistry yielding an acidic nature allowed these low-T activated hydrochars to present the best overall recoveries (between 20.9 and 82.4%) for the simultaneous determination of the ten target PhCs with very distinct chemical properties using high performance liquid chromatography-diode array detection (HPLC-DAD).

Development and validation of a comprehensive solid-phase extraction method followed by LC-TOF/MS for the analysis of eighteen pharmaceuticals in influent and effluent of sewage treatment plants

The scarcity of data about the occurrence of pharmaceuticals in water bodies in Malaysia prompted us to develop a suitable analytical method to address this issue. We therefore developed a method based on solid-phase extraction combined with liquid chromatography-time of flight/mass spectrometry (SPE-LC-TOF/MS) for the analysis of sixteen prescribed and two nonprescribed pharmaceuticals that are potentially present in water samples. The levels of these pharmaceuticals, which were among the top 50 pharmaceuticals consumed in Malaysia during the period 2011-2014, in influent and effluent of five sewage treatment plants (STPs) in Bangi, Malaysia, were then analyzed using the developed method. All of the pharmaceuticals were separated chromatographically using a 5 μm, 2.1 mm × 250 mm C18 column at a flow rate of 0.3 mL/min. Limits of quantification (LOQs) were 0.3-8.2 ng/L, 6.5-89 ng/L, and 11.1-93.8 ng/L in deionized water (DIW), STP effluent, and STP influent, respectively, for most of the pharmaceuticals. Recoveries were 51-108%, 52-118%, and 80-107% from the STP influent, STP effluent, and DIW, respectively, for most of the pharmaceuticals. The matrix effect was also evaluated. The signals from carbamazepine, diclofenac sodium, and mefenamic acid were found to be completely suppressed in the STP influent. The signals from other compounds were found to be influenced by matrix effects more strongly in STP influent (enhancement or suppression of signal ≤180%) than in effluent (≤94%). The signal from prednisolone was greatly enhanced in the STP influent, indicating a matrix effect of -134%. Twelve pharmaceuticals were frequently detected in all five STPs, and caffeine, prazosin, and theophylline presented the highest concentrations among all the pharmaceuticals monitored: up to 7611, 550, and 319 ng/L in the STP influent, respectively. To the best of our knowledge, this is the first time that prazosin has been detected in a water matrix in Malaysia. Graphical abstract ᅟ.

Determination of Ochratoxin A in Wheat and Maize by Solid Bar Microextraction with Liquid Chromatography and Fluorescence Detection

Solid bar microextraction (SBME), followed by liquid chromatography with fluorescence detection (HPLC-FLD), for the quantification of ochratoxin A in wheat and maize was developed. Ground wheat and maize grains were extracted with acetonitrile-water-acetic acid (79:20:1, v/v/v), followed by defatting with cyclohexane, and subjected to SBME-LC-FLD analysis. SBME devices were constructed by packing 2 mg sorbent (C18) into porous polypropylene micro-tubes (2.5 cm length, 600 μm i.d., and 0.2 μm pore size). SBME devices were conditioned with methanol and placed into 5 mL stirred sample solutions for 70 min. After extraction, OTA was desorbed into 200 μL of methanol for 15 min, the solution was removed in vacuum, the residue was dissolved in 50 μL of methanol-water (1:1, v/v) and ochratoxin A content was determined by HPLC-FLD. Under optimized extraction conditions, the limit of detection of 0.9 μg·kg⁻¹ and 2.5 μg·kg⁻¹ and the precision of 3.4% and 5.0% over a concentration range of 1 to 100 μg·kg⁻¹ in wheat and maize flour, respectively, were obtained.

Chiral liquid membrane for enantioselective separation of racemic ibuprofen by l-tartaric acid derivatives

Use of a chiral liquid membrane is an attractive separation method for racemic ibuprofen, and the separation factor could be up to 1.38 under optimal experimental conditions.