GC–MS Determination of Atenolol Plasma Concentration after Derivatization with N-methyl-N-(trimethylsilyl)trifluoroacetamide

Supramolecular Interaction of Atenolol and Propranolol with β-Cyclodextrin Spectroscopic Characterization and Analytical Application

Atenolol (ATE) and propranolol (PRO) inclusion complexes with β-cyclodextrin have been investigated in aqueous solution. The aqueous solution was examined and characterized using UV-vis, fluorescence spectroscopy, and 1H NMR. The physical mixture was characterized using FTIR. The existence of inclusion complexes is confirmed by observing changes in spectroscopic properties. The ATE complex with β-CD exhibited an interaction as host and (β-CD) as a guest in a 1:1 ratio, with an inclusion constant K of 2.09 × 10-3 µM-1, as determined by the typical double-reciprocal graphs. Similarly, the PRO complex with β-CD exhibited an interaction as host and (β-CD) guest in 1:1 and 1:2 stoichiometry at the same time; the inclusion constants were K1 = 5.80 × 10-5 µM-1 and K2 = 4.67 × 10-8 µM-1, as determined by typical double-reciprocal graphs. The variables influencing the formation of the inclusion complexes were investigated and optimized. Based on the enhancement in fluorescence intensity due to the formation of inclusion complexes, spectrofluorometric methods were developed and validated for determination of each drug's pharmaceutical formulation. The quantification of the fluorescence intensity for ATE and PRO was conducted at λex/λem 226/302 nm and λex/λem 231/338 nm, respectively. Under the optimal reaction circumstances, linear relationships with good correlation coefficients of 0.9918 and 0.99 were found in the concentration ranges of 0.3-1.7 μM, and 0.1-1.1 μM for ATE and PRO, respectively. The limits of detection (LODs) were found to be 0.13 and 0.01 μM for ATE and PRO, respectively. The suggested approach was effectively applied to the analysis of both drugs' pharmaceutical formulations.

Utilizing a nanocomposite aerogel grafted with Fe3O4@GO for the extraction and determination of metoprolol in exhaled breath condensate

This article presents a solid-phase extraction method combined with a spectrofluorometric method for the extraction/pre-concentration and determination of metoprolol (MET) in exhaled breath condensate. The extraction sorbent is an agarose aerogel nanocomposite grafted with graphene oxide (GO) Fe3O4. The size and morphology of the nanosorbent were characterized via X-ray crystallography, scanning electron microscopy, Fourier-transform infrared spectrometry, and Brunauer-Emmett-Teller analysis. Factors affecting the extraction/determination of MET were optimized using the one-at-a-time method. Under optimized experimental conditions, the calibration graph was linear in the range of 0.005 to 2.0 μg mL-1 with a detection limit of 0.001 μg mL-1. The method was successfully applied for the determination of MET in biological samples taken from patients receiving MET.

Rapid and sensitive tapered-capillary microextraction combined to on-line sample stacking-capillary electrophoresis for extraction and quantification of two beta-blockers in human urine

A tapered-capillary microextraction (tCap-μEx) combining with field-amplified stacking (FASI) method for CE analysis was developed. The tCap-μEx method is based on the construction of a micro solid phase extraction (SPE) column by narrowing the end of a silica capillary from 530µm (inner diameter) to 20µm, enabling the packing of 45µm sorbent particles without a frit. Various parameters that may affect the microextraction and FASI-CE analysis have been investigated and optimized. This study shows that microextraction exhibits advantages of small sample and sorbent volumes (less than 200μL sample and 2μL sorbent) and fast extraction time of 6min. The method was successfully applied for efficient determination of atenolol and metoprolol in human urine samples, with recovery of 93.7-105.5% and RSD (n=3) lower than 8.5%. Twenty-one-fold and nineteen-fold average enhancement of detection sensitivity was achieved for atenolol and metoprolol, respectively, versus the CE method without tCap-μEx and FASI. The method is environmentally friendly and allows reuse of the sorbent at least 8 times without an obvious loss in performance. The results indicate that the proposed method could be potentially applied in a wide range of doping control, clinical, forensic toxicology, food analysis and environmental analyses.

Simple high-performance liquid chromatography method for formaldehyde determination in human tissue through derivatization with 2,4-dinitrophenylhydrazine

A simple high-performance liquid chromatography method has been developed for the determination of formaldehyde in human tissue. FA Formaldehyde was derivatized with 2,4-dinitrophenylhydrazine. It was extracted from human tissue with ethyl acetate by liquid-liquid extraction and analyzed by high-performance liquid chromatography. The calibration curve was linear in the concentration range of 5.0-200 μg/mL. Intra- and interday precision values for formaldehyde in tissue were <6.9%, and accuracy (relative error) was better than 6.5%. The extraction recoveries of formaldehyde from human tissue were between 88 and 98%. The limits of detection and quantification of formaldehyde were 1.5 and 5.0 μg/mL, respectively. Also, this assay was applied to liver samples taken from a biopsy material.

HPLC method for naproxen determination in human plasma and its application to a pharmacokinetic study in Turkey

A simple high-performance liquid chromatography method has been developed for the determination of naproxen in human plasma. The method was validated on an Ace C18 column using ultraviolet detection. The mobile phase consisted of 20 mM phosphate buffer (pH 7) containing 0.1% trifluoroacetic acid-acetonitrile (65:35, v/v). The calibration curve was linear between the concentration ranges of 0.10 and 5.0 µg/mL. Intra-day and inter-day precision values for naproxen in plasma were less than 4.84, and accuracy (relative error) was better than 3.67%. The extraction recovery values of naproxen from human plasma were between 91.0 and 98.9%. The limits of detection and quantification of naproxen were 0.03 and 0.10 µg/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of naproxen in six healthy Turkish volunteers who had been given 220 mg of naproxen.

Quantitative determination of atenolol in dried blood spot samples by LC-HRMS: a potential method for assessing medication adherence

The use of blood spot collection cards was investigated as a means of obtaining small volume samples for the quantification of therapeutic drugs for assessing medication adherence. A liquid chromatography-high resolution TOF mass spectrometry (LC-HRMS) method, based on the measurement at the accurate mass to charge ratio of the target analyte, was used to ensure specificity for atenolol in the dried blood spot (DBS) samples. A working method was developed and validated. For the preparation of DBS samples whole blood spiked with analyte was used to produce 30 μl blood spots on specimen collection cards. A 5mm disc was cut from the dried blood spot and extracted using methanol:water (60:40, v/v) containing the internal standard, atenolol-d(7). Extracts were vortexed, sonicated and then centrifuged. Gradient chromatographic elution was achieved using an Ascentis Express C18 100mm×2.1mm column and a mobile phase flow rate of 0.2 ml/min and the column oven temperature at 30 °C. MS detection was carried out in electrospray positive ion mode for target ions at accurate mass m/z 267.1703 for atenolol and 274.2143 for the IS. Drug extraction efficiency from spiked blood spots was demonstrated to be 96±5% and the drug was stable in DBS for at least 10 weeks. The developed LC-HRMS method was linear within the tested calibration range of 25-1500 ng/ml and validation showed the accuracy (relative error) and precision (coefficient of variation) values were within the pre-defined limits of ≤ 5% at all concentrations with a limit of quantification of 25 ng/ml. Factors with potential to affect drug quantification measurements such as the matrix effects, volume of blood applied onto the collection card and effect of different sampling cards were investigated. The developed LC-HRMS method was applied to blood spots on sampling card taken from adult healthy volunteers previously administered a 50mg atenolol tablet and a DBS concentration-time profile was obtained for atenolol. Requiring only a micro volume (30 μl) blood sample for analysis, the developed DBS based assay has the potential to assess patient adherence to atenolol.

Determination of metoprolol in human plasma and urine by high-performance liquid chromatography with fluorescence detection

A simple, specific and sensitive HPLC method has been developed for the determination of metoprolol in human plasma and urine. Separation of metoprolol and atenolol (internal standard) was achieved on an Ace C(18) column (5 microm, 250 mm x 4.6 mm id) using fluorescence detection with lambda(ex)=276 nm and lambda(em)=296 nm. The mobile phase consists of methanol-water (50:50, v/v) containing 0.1% TFA. The analysis was performed in less than 10 min with a flow rate of 1 mL/min. The assay was linear over the concentration range of 3-200 and 5-300 ng/mL for plasma and urine, respectively. The LOD were 1.0 and 1.5 ng/mL for plasma and urine, respectively. The LOQ were 3.0 and 5.0 ng/mL for plasma and urine, respectively. The extraction recoveries were found to be 95.6 +/- 1.53 and 96.4 +/- 1.75% for plasma and urine, respectively. Also, the method was successfully applied to three patients with hypertension who had been given an oral tablet of 100 mg metoprolol.