In Vivo Functional Effects of CYP2C9 M1L, a Novel and Common Variant in the Yup'ik Alaska Native Population.

Alaska Native people are under-represented in genetic research but have unique gene variation that may critically impact their response to pharmacotherapy. Full resequencing of CYP2C9 in a cross-section of this population identified CYP2C9 Met1Leu (M1L), a novel, relatively common single nucleotide polymorphism hypothesized to confer CYP2C9 poor metabolizer phenotype by disrupting the start codon. M1L is present at a minor allele frequency of 6.3% in Yup'ik Alaska Native people and thus can contribute to the risk of an adverse drug response from narrow-therapeutic-index CYP2C9 substrates such as (S)-warfarin. This study's objective was to characterize the catalytic efficiency of the Leu1 variant enzyme in vivo by evaluating the pharmacokinetic behavior of naproxen, a probe substrate for CYP2C9 activity, in genotyped Yup'ik participants. We first confirmed the selectivity of (S)-naproxen O-demethylation by CYP2C9 using activity-phenotyped human liver microsomes and selective cytochrome P450 inhibitors and then developed and validated a novel liquid chromatography mass spectrometry method for simultaneous quantification of (S)-naproxen, (S)-O-desmethylnaproxen, and naproxen acyl glucuronide in human urine. The average ratio of (S)-O-desmethylnaproxen to unchanged (S)-naproxen in urine was 18.0 ± 8.0 (n = 11) for the homozygous CYP2C9 Met1 reference group and 10.3 ± 6.6 (n = 11) for the Leu1 variant carrier group (P = 0.011). The effect of M1L variation on CYP2C9 function and its potential to alter the pharmacokinetics of drugs metabolized by the enzyme has clinical implications and should be included in a variant screening panel when pharmacogenetic testing in the Alaska Native population is warranted. SIGNIFICANCE STATEMENT: The novel CYP2C9 Met1Leu variant in Alaska Native people was recently identified. This study validated (S)-naproxen as a CYP2C9 probe substrate to characterize the in vivo functional activity of the CYP2C9 Leu1 variant. The results of this pharmacogenetic-pharmacokinetic study suggest that the CYP2C9 Leu1 variant exhibits loss of enzyme activity. This finding may be important to consider when administering narrow-therapeutic-index medications metabolized by CYP2C9 and also compels further investigation to characterize novel genetic variation in understudied populations.

A Molecularly Imprinted Polymer-based Dye Displacement Assay for the Rapid Visual Detection of Amphetamine in Urine.

The rapid sensing of drug compounds has traditionally relied on antibodies, enzymes and electrochemical reactions. These technologies can frequently produce false positives/negatives and require specific conditions to operate. Akin to antibodies, molecularly imprinted polymers (MIPs) are a more robust synthetic alternative with the ability to bind a target molecule with an affinity comparable to that of its natural counterparts. With this in mind, the research presented in this article introduces a facile MIP-based dye displacement assay for the detection of (±) amphetamine in urine. The selective nature of MIPs coupled with a displaceable dye enables the resulting low-cost assay to rapidly produce a clear visual confirmation of a target's presence, offering huge commercial potential. The following manuscript characterizes the proposed assay, drawing attention to various facets of the sensor design and optimization. To this end, synthesis of a MIP tailored towards amphetamine is described, scrutinizing the composition and selectivity (ibuprofen, naproxen, 2-methoxphenidine, quetiapine) of the reported synthetic receptor. Dye selection for the development of the displacement assay follows, proceeded by optimization of the displacement process by investigating the time taken and the amount of MIP powder required for optimum displacement. An optimized dose-response curve is then presented, introducing (±) amphetamine hydrochloride (0.01-1 mg mL-1) to the engineered sensor and determining the limit of detection (LoD). The research culminates in the assay being used for the analysis of spiked urine samples (amphetamine, ibuprofen, naproxen, 2-methoxphenidine, quetiapine, bupropion, pheniramine, bromopheniramine) and evaluating its potential as a low-cost, rapid and selective method of analysis.

Magnetic Solid-Phase Extraction Based on Poly 4-Vinyl Pyridine for HPLC-FLD Analysis of Naproxen in Urine Samples.

A magnetic solid phase extraction technique followed by liquid chromatography with a fluorescence detector for naproxen analysis in human urine samples was developed. The method includes the extraction of naproxen with a magnetic solid synthetized with magnetite and poly 4-vinylpriridine, followed by the magnetic separation of the solid phase and desorption of the analyte with methanol. Under optimal conditions, the linear range of the calibration curve was 0.05-0.60 µg L-1, with a limit of detection of 0.02 µg L-1. In all cases values of repeatability were lower than 5.0% with recoveries of 99.4 ± 1.3%. Precision and accuracy values are adequate for naproxen (Npx) analysis in urine samples.

Non-steroidal anti-inflammatory drugs increase urinary neutrophil gelatinase-associated lipocalin in recreational runners.

OBJECTIVES: To study the effects of running with/without the use of pain killers on urinary neutrophil gelatinase-associated lipocalin (uNGAL) and other parameters of kidney function in recreational runners. METHODS: Participants of the 10- and 21.1-km Weir Venloop race were enrolled and their urine samples collected before and after the run. Urine dipstick and other conventional tests used to assess kidney function were performed. The presence of ibuprofen, diclofenac, naproxen, and/or paracetamol was assessed by LC-MS/MS. uNGAL was measured with a two-step chemiluminescent immunoassay. RESULTS: NSAIDs/analgesics were detected in urine of 5 (14.4%) 10-km runners and 13 (28.9%) 21.1-km runners. Only half-marathon participants showed significant increases in uNGAL (pre: 11.7 [7.1-34.3] ng/mL; post: 33.4 [17.4-50.4] ng/mL; P = .0038). There was a significant effect of NSAID/analgesic use on uNGAL increase (F2, 76  = 4.210, P = .004). Post hoc tests revealed that uNGAL increased significantly in runners who tested positive for ibuprofen/naproxen compared to runners who did not use any medications (P = .045) or those who tested positive for paracetamol (P = .033). Running distance had a significant influence on the increase in uNGAL (F1, 53  = 4.741, P < .05), specific gravity (F1, 60  = 9.231, P < .01), urinary creatinine (F1, 61  = 10.574, P < .01), albumin (F1, 59  = 4.888, P < .05), and development of hematuria (χ2 (4) = 18.44, P = .001). CONCLUSIONS: Running distance and use of ibuprofen/naproxen were identified as risk factors for uNGAL increase in recreational runners.

Simultaneous voltammetric determination of acetaminophen, naproxen, and theophylline using an in-situ polymerized poly(acrylic acid) nanogel covalently grafted onto a carbon black/La2O3 composite.

Lanthanum oxide nanomaterials were decorated with carbon black (CB) and grafted with a poly(acrylic acid) nanogel to obtain a composite material (CB-g-PAA/La2O3) for simultaneous determination of acetaminophen (AMP), naproxen (NPX), and theophylline (TPH). The nanogel was synthesized by in-situ free radical polymerization. The composite was dropped onto a glassy carbon electrode (GCE), and the modified GCE displays robust electrocatalytic activity towards AMP, NPX, and TPH, with voltammetric signals that are enhanced compared to a bare GCE. Features of merit for AMP, NPX, and TPH, respectively, include (a) peak potentials of 0.42, 0.85 and 0.12 V (vs. Ag/AgCl), (b) linear ranges from 0.05-887, 0.05-884, and 0.02-888 µM, and (c) detection limits of 20, 35, and 15 nM. The practical applicability of the CB-g-PAA/La2O3/GCE was illustrated by analyzing serum and urine samples. Graphical abstract Schematic presentation of simultaneous electrochemical sensing of acetaminophen (AMP), naproxen (NPX), and theophylline (TPH) in real sample analysis using poly(acrylic acid) nanogel covalently grafted onto a carbon black/La2O3 composite (CB-g-PAA/La2O3/GCE).

Combustion fabrication of magnetic porous carbon as a novel magnetic solid-phase extraction adsorbent for the determination of non-steroidal anti-inflammatory drugs.

Based on a one-step combustion fabrication approach, a novel magnetic porous carbon (MPC) was fabricated using filter paper as porous carbon source and iron salts as magnetic precursors. The textural properties of the MPC were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), vibration sample magnetometer (VSM) and nitrogen absorption-desorption isotherms. The as-prepared MPC possessed a high specific surface area, a microstructure comprised of mesopores and strong magnetic response. It was employed as a magnetic solid-phase extraction (MSPE) adsorbent for the determination of three non-steroidal anti-inflammatory drugs (NSAIDs) in environmental water and biological samples coupled with high performance liquid chromatography (HPLC). The main parameters affecting extraction efficiency were investigated in detail and a satisfactory performance was obtained under the optimal conditions. The calibration curves were linear over the concentration ranging from 1 to 1200 µg L-1 for ketoprofen (KET) and 2-1200 µg L-1 for naproxen (NAP) and diclofenac (DCF) with determination coefficients (R2) between 0.9995 and 0.9997. The limits of detection (LODs) were in the range of 0.2-0.4 µg L-1. The intra- and inter-day relative standard deviations (RSDs) were less than 4.03% and 8.72%, respectively. The recoveries ranged from 84.67% to 113.73% with RSDs less than 7.76%. The satisfactory results confirmed the great potential of the novel MPC adsorbent for the extraction of NSAIDs from complex sample matrices.

Physical-chemical interactions between pharmaceuticals and biochar in synthetic and real urine.

This research advances the knowledge of the pharmaceutical removal interactions by biochar in synthetic and real urine through the use of reference adsorbents and adsorbate probes. Earlier work has combined biochar and urine for pharmaceutical removal, however, the interactions that influence adsorption are unknown. In this study, bamboo biochar and softwood biochar were chosen as the representative materials and the model pharmaceuticals were naproxen and paracetamol. To further investigate the physical-chemical interactions, two nonpolar adsorbates, para-xylene and dimethylnaphthalene, were tested. Graphite and anion exchange resin, were used to isolate van der Waals and electrostatic interactions, respectively. Experimental kinetic and equilibrium data were fit to multiple adsorption models where the pseudo-second order and Freundlich exhibited the best fit, respectively. The Freundlich and Langmuir parameters had similar trends showing that softwood had the highest adsorption capacity. The model parameters indicated higher selectivity for nonpolar para-xylene and dimethylnaphthalene by graphite and polar paracetamol and naproxen by softwood biochar. The decreasing trend of importance of key interactions for pharmaceutical sorption to biochar are: van der Waals > hydrogen bonding > electrostatic interactions. No statistically significant difference was found between urine age (fresh vs. hydrolyzed) and pharmaceutical removal; however, the urine matrix (synthetic vs. synthetic with metabolites vs. real urine) did show a statistically significant difference on pharmaceutical removal where synthetic urine had comparatively greater adsorption. As constituents (i.e., metabolites) were added to urine matrices, reduced adsorption of pharmaceuticals was observed, indicating that adsorption processes should be tested in real urine for accuracy.

New spectrophotometric/chemometric assisted methods for the simultaneous determination of imatinib, gemifloxacin, nalbuphine and naproxen in pharmaceutical formulations and human urine.

In this paper, novel univariate and multivariate regression methods along with model-updating technique were developed and validated for the simultaneous determination of quaternary mixture of imatinib (IMB), gemifloxacin (GMI), nalbuphine (NLP) and naproxen (NAP). The univariate method is extended derivative ratio (EDR) which depends on measuring every drug in the quaternary mixture by using a ternary mixture of the other three drugs as divisor. Peak amplitudes were measured at 294nm, 250nm, 283nm and 239nm within linear concentration ranges of 4.0-17.0, 3.0-15.0, 4.0-80.0 and 1.0-6.0µgmL-1 for IMB, GMI, NLP and NAB, respectively. Multivariate methods adopted are partial least squares (PLS) in original and derivative mode. These models were constructed for simultaneous determination of the studied drugs in the ranges of 4.0-8.0, 3.0-11.0, 10.0-18.0 and 1.0-3.0µgmL-1 for IMB, GMI, NLP and NAB, respectively, by using eighteen mixtures as a calibration set and seven mixtures as a validation set. The root mean square error of predication (RMSEP) were 0.09 and 0.06 for IMB, 0.14 and 0.13 for GMI, 0.07 and 0.02 for NLP and 0.64 and 0.27 for NAP by PLS in original and derivative mode, respectively. Both models were successfully applied for analysis of IMB, GMI, NLP and NAP in their dosage forms. Updated PLS in derivative mode and EDR were applied for determination of the studied drugs in spiked human urine. The obtained results were statistically compared with those obtained by the reported methods giving a conclusion that there is no significant difference regarding accuracy and precision.

Use of Polymer Inclusion Membranes (PIMs) as support for electromembrane extraction of non-steroidal anti-inflammatory drugs and highly polar acidic drugs.

The use of polymer inclusion membranes (PIMs) as support of 1-octanol liquid membrane in electromembrane extraction (EME) procedure is proposed. Synthesis of PIMs were optimized to a composition of 29% (w/w) of cellulose triacetate as base polymer and 71% (w/w) of Aliquat®336 as cationic carrier. Flat PIMs of 25µm thickness and 6mm diameter were used. EME protocol was implemented for the simultaneous extraction of four non-steroidal anti-inflammatory drugs (NSAIDs) (salicylic acid, ketoprofen, naproxen and ibuprofen) and four highly polar acidic drugs (anthranilic acid, nicotinic acid, amoxicillin and hippuric acid). Posterior HPLC separation of the extracted analytes was developed with diode array detection. Recoveries in the 81-34% range were obtained. EME procedure was applied to human urine samples.

In-line coupling of supported liquid membrane extraction to capillary electrophoresis for simultaneous analysis of basic and acidic drugs in urine.

Simultaneous extraction of basic and acidic drugs across thin supported liquid membrane (SLM) and direct injection of the extracted drugs from SLM surface into capillary electrophoresis (CE) were demonstrated. A microextraction device compatible with injection system of commercial CE instrument was filled with 20µL of sample and 10µL of acceptor solution, which were interspaced by the SLM impregnated with 5µL of organic solvent. Extractions of three basic drugs (nortriptyline, haloperidol and loperamide) and two acidic drugs (ketoprofen and naproxen) were achieved at optimized conditions including 1-ethyl-2-nitrobenzene as SLM solvent, natural pH of sample solution, 2.5mM NaOH acceptor solution and 30min extraction time. The extracted drugs were directly injected into CE for separation and quantification in a background electrolyte solution consisting of 30mM ammonium acetate adjusted to pH 4.2 with acetic acid. The entire analytical procedure including drugs extraction, injection, separation and quantification was automated in the CE instrument and the only manual procedures were SLM impregnation and filling the microextraction device with sample and acceptor solutions. The analytical method was suitable for simultaneous determination of basic and acidic drugs in undiluted human urine samples and was used for direct determination of naproxen in urine after oral administration of Nalgesin S tablet. Efficient elimination of sample matrix and selective transfer of basic and acidic drugs were achieved and the hyphenated SLM-CE method was characterized by repeatability of peak areas ranging from 3.7 to 13.4%, linear relationship between peak areas and concentrations (r2=0.994-0.999) and limits of detection between 0.05 and 1.5µg/mL.

An efficient approach to selective electromembrane extraction of naproxen by means of molecularly imprinted polymer-coated multi-walled carbon nanotubes-reinforced hollow fibers.

In this work, a novel microextraction technique using molecularly imprinted polymer-coated multi-walled carbon nanotubes (MIP-MWCNTs) in electromembrane extraction (EME) procedure is described. The method in combination with HPLC-UV was utilized to determine naproxen, as an acidic model drug, in urine, plasma and wastewater samples. For this purpose, MIP-MWCNTs were placed in the pores of polypropylene hollow fiber. The MIP-MWCNTs-EME method has the advantages of high selectivity and cleanup of MIP along with high enrichment ability of the EME in a single step extraction. Continuing with the research, optimization of the factors affecting the migration of naproxen from sample solutions to MIP-MWCNTs sites and then into the lumen of hollow fiber was explored. Under the optimized conditions, the limit of detection (LOD) of the developed method was calculated to be 0.3µgL-1. All relative standard deviations (RSDs) were lower than 3%. Linearity of the method was obtained within the range of 1-1000µgL-1 with the coefficient of determination (r2) being higher than 0.999. Under the optimized conditions, an extraction recovery of 66% was obtained, which corresponded to a preconcentration factor of 88. Finally, the developed method was satisfactorily used to determine naproxen in urine, plasma and wastewater samples.

Single-drop microextraction combined in-line with capillary electrophoresis for the determination of nonsteroidal anti-inflammatory drugs in urine samples.

This study describes a method to determine nonsteroidal anti-inflammatory drugs (NSAIDs) in urine samples based on the use of single-drop microextraction (SDME) in a three-phase design as a preconcentration technique coupled in-line to capillary electrophoresis. Different parameters affecting the extraction efficiency of the SDME process were evaluated (e.g. type of extractant, volume of the microdroplet, and extraction time). The developed method was successfully applied to the analysis of human urine samples with LODs ranging between 1.0 and 2.5 µg/mL for all of the NSAIDs under study. This method shows RSD values ranging from 8.5 to 15.3% in interday analysis. The enrichment factors were calculated, resulting 27-fold for ketoprofen, 14-fold for diclofenac, 12-fold for ibuprofen, and 44-fold naproxen. Samples were analyzed applying the SDME-CE method and the obtained results presented satisfactory recovery values (82-115%). The overall method can be considered a promising approach for the analysis of NSAIDs in urine samples after minimal sample pretreatment.

Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop combined with high performance liquid chromatography for determination of naproxen and nabumetone.

A novel, rapid, simple and green vortex-assisted surfactant-enhanced emulsification microextraction method based on solidification of floating organic drop was developed for simultaneous separation/preconcentration and determination of ultra trace amounts of naproxen and nabumetone with high performance liquid chromatography-fluorescence detection. Some parameters influencing the extraction efficiency of analytes such as type and volume of extractant, type and concentration of surfactant, sample pH, KCl concentration, sample volume, and vortex time were investigated and optimized. Under optimal conditions, the calibration graph exhibited linearity in the range of 3.0-300.0ngL(-1) for naproxen and 7.0-300.0ngL(-1) for nabumetone with a good coefficient of determination (R(2)>0.999). The limits of detection were 0.9 and 2.1ngL(-1). The relative standard deviations for inter- and intra-day assays were in the range of 5.8-10.1% and 3.8-6.1%, respectively. The method was applied to the determination of naproxen and nabumetone in urine, water, wastewater and milk samples and the accuracy was evaluated through recovery experiments.

Dendrimer-functionalized mesoporous silica as a reversed-phase/anion-exchange mixed-mode sorbent for solid phase extraction of acid drugs in human urine.

A new dendrimer-functionalized mesoporous silica material based on large-pore 3D cubic Korea Advanced Institute of Science and Technology-6 (KIT-6) was synthesized by the growing of dendritic branches inside the mesopores of aminopropyl functionalized KIT-6. Detailed physical characterizations using transmission electron microscopy, nitrogen adsorption-desorption measurements, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis reveal that the multifunctional dendrimers have been grown successfully within the confined spaces of mesopores. Although the 3D ordered mesoporous architecture of KIT-6 was well preserved, there was a significant and continuous decrease in pore size, specific surface area (SBET) and pore volume when increasing dendrimer generation up to six. In order to get a compromise between the SBET, pore size and density of functionalities, the dendrimer-functionalized KIT-6 (DF-KIT-6) for generation 2 (SBET, 314.2 m(2) g(-1); pore size, 7.9 nm; carbon and nitrogen contents, 19.80% and 1.92%) was selected for solid phase extraction (SPE) applications. The DF-KIT-6 was then evaluated as a reversed-phase/anion-exchange mixed-mode sorbent for extraction of the selected acidic drugs (ketoprofen, KEP; naproxen, NAP; and ibuprofen, IBU), since the dendrimers contained both hydrocarbonaceous and amine functionalities. The effective parameters on extraction efficiency such as sample pH and volume, type and volume of eluent and wash solvents were optimized. Under the optimized experimental conditions, the DF-KIT-6 based SPE coupled with HPLC-UV method demonstrated good sensitivity (0.4-4.6 ng mL(-1) detection of limits) and linearity (R(2)>0.990 for 10-2000 ng mL(-1) of KEP and IBU, and 1-200 ng mL(-1) of NAP). The potential use of DF-KIT-6 sorbent for preconcentration and cleanup of acid drugs in human urine samples was also demonstrated. Satisfactory recoveries at two spiking levels (30 and 300 ng mL(-1) for KEP and IBU, 3 and 30 ng mL(-1) for NAP) were obtained in the range of 85.7-113.9% with RSD values below 9.3% (n=3).

Ion-exchange selectivity of diclofenac, ibuprofen, ketoprofen, and naproxen in ureolyzed human urine.

This research advances the knowledge of ion-exchange of four non-steroidal anti-inflammatory drugs (NSAIDs) - diclofenac (DCF), ibuprofen (IBP), ketoprofen (KTP), and naproxen (NPX) - and one analgesic drug-paracetamol (PCM) - by strong-base anion exchange resin (AER) in synthetic ureolyzed urine. Freundlich, Langmuir, Dubinin-Astakhov, and Dubinin-Radushkevich isotherm models were fit to experimental equilibrium data using nonlinear least squares method. Favorable ion-exchange was observed for DCF, KTP, and NPX, whereas unfavorable ion-exchange was observed for IBP and PCM. The ion-exchange selectivity of the AER was enhanced by van der Waals interactions between the pharmaceutical and AER as well as the hydrophobicity of the pharmaceutical. For instance, the high selectivity of the AER for DCF was due to the combination of Coulombic interactions between quaternary ammonium functional group of resin and carboxylate functional group of DCF, van der Waals interactions between polystyrene resin matrix and benzene rings of DCF, and possibly hydrogen bonding between dimethylethanol amine functional group side chain and carboxylate and amine functional groups of DCF. Based on analysis of covariance, the presence of multiple pharmaceuticals did not have a significant effect on ion-exchange removal when the NSAIDs were combined in solution. The AER reached saturation of the pharmaceuticals in a continuous-flow column at varying bed volumes following a decreasing order of DCF > NPX ≈ KTP > IBP. Complete regeneration of the column was achieved using a 5% (m/m) NaCl, equal-volume water-methanol solution. Results from multiple treatment and regeneration cycles provide insight into the practical application of pharmaceutical ion-exchange in ureolyzed urine using AER.

Electrochemically controlled in-tube solid phase microextraction of naproxen from urine samples using an experimental design.

A new in-tube solid phase microextraction approach named electrochemically controlled in-tube solid phase microextraction (EC in-tube SPME) has been reported. In this approach, in which electrochemistry and in-tube SPME were combined, the total analysis time was decreased and the sensitivity was increased. After electropolymerization of pyrrole on the inner surface of a stainless steel tube, the polypyrrole (PPy)-coated in-tube SPME was coupled on-line to high performance liquid chromatography (HPLC) to achieve automated in-tube SPME-HPLC analysis. After the completion of the EC-in-tube SPME-HPLC system, the PPy-coated tube was used as a working electrode for the uptake of naproxen. It was found that the extraction efficiency could be significantly enhanced using the constant potential. Plackett-Burman design was employed for screening, to determine the variables significantly affecting the extraction efficiency. The significant factors were then optimized using a Box-Behnken design. The linear range and detection limit (S/N = 3) were 0.5-1000 and 0.07 µg L(-1), respectively. Urine samples were successfully analyzed by the proposed method.

Electrospun titania sol-gel-based ceramic composite nanofibers for online micro- solid-phase extraction with high-performance liquid chromatography.

Titanium(IV) tetraisopropoxide was employed as a metal oxide sol-gel precursor to prepare ceramic composite nanofibers by the electrospinning system. To facilitate this process and obtain the desired nanofibers with higher aspect ratios and surface area, poly(vinylpyrrolidone) was added to the sol of titania. Four ceramic nanofibers sheets based on titania were prepared while each sheet contained different transition metals such as Fe-Mn, Fe-Ni, Fe-Co, and Fe-Mn-Co-Ni. The scanning electron microscope images showed good homogeneity for all the prepared ceramic composites with a diameter range of 100-250 nm. The sorption efficiency was investigated by a micro-solid-phase extraction setup in online combination with high-performance liquid chromatography for the determination of naproxen and clobetasol. All the prepared composites exhibited comparable efficiencies for the desired analytes and the type of metal showed insignificant effect. For the selected composite with Fe-Mn, the linearity of the analytes was in the range of 1-1000 µg/L and the limit of detection values were found to be 2 and 0.3 µg/L for naproxen and clobetasol, respectively. The developed method was extended to the analysis of urine and blood plasma samples and acceptable relative standard deviations were obtained at two concentration levels.

Selective solid-phase extraction of naproxen drug from human urine samples using molecularly imprinted polymer-coated magnetic multi-walled carbon nanotubes prior to its spectrofluorometric determination.

A drug imprinted polymer based on suspension polymerization on magnetic multi-walled carbon nanotubes (MIPMCNTs) was prepared with a synthesized amidoamine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, naproxen (NAP) as the template and ammonium persulfate as the initiator. The MIPMCNTs were characterized by TEM, FT-IR and XRD measurements. The prepared magnetic adsorbent can be well dispersed in aqueous media and can be easily separated magnetically from the medium after loading with NAP. All the aspects influencing the adsorption (extraction time, adsorbent dosage and pH) and desorption (desorption time and desorption solvent) of the analyte on the MIPMCNTs have been investigated. The extracted NAP could be easily desorbed with a mixture of methanol/sodium hydroxide aqueous solution and determined spectrofluorometrically at λem = 353 nm (λex = 271 nm). A linear dynamic range was established from 4.0 to 40.0 ng mL⁻¹ of NAP and the limit of detection (LOD) was found to be 2.0 ng mL⁻¹. In addition, the equilibrium adsorption data of NAP by imprinted polymer were analyzed by Langmuir and Freundlich isotherm models. The developed method was utilized for the determination of NAP in human urine samples with satisfactory results.

Water stable metal-organic framework packed microcolumn for online sorptive extraction and direct analysis of naproxen and its metabolite from urine sample.

The metal-organic framework MIL-101 was fabricated in a polyetheretherketone (PEEK) tube as micro-trapping device, and applied to sorptive extraction of naproxen and its metabolite in urine samples. The remarkable water stability of the MIL-101 characterizes the material as being different from other moisture sensitive metal-organic framework. It is therefore suitable for extraction of pharmaceuticals from biological fluids. The adsorption isotherms in aqueous solution showed that the adsorption of naproxen on MIL-101 is endothermic. Additionally, MIL-101 exhibited higher extraction capacity to naproxen than that of C18-bonded silica and multi-walled nanotube. A specially designed in-tube sorptive extraction (ITSE) device endows the extraction process with the characteristic of rapidness, convenience, and easy of conjunction with high performance liquid chromatography (HPLC). Finally the MIL-101 based ITSE method coupled with HPLC and fluorescence detection was applied to analysis of naproxen and 6-O-desmethylnaproxen in urine samples. Parameters that influence the online extraction procedure, including pH of the sample solution, flow rate of extraction, sample volume, desorption solvents and time were investigated. The method is proved to be highly sensitive with the linear range of 0.05-6.0µgL(-1) and the limits of detection of 0.034 and 0.011µgL(-1) for naproxen and 6-O-desmethylnaproxen, respectively. The recoveries in urine samples were 85.3-98.3% for naproxen and 94.0-97.3% for 6-O-desmethylnaproxen with intra- and inter-day RSDs of 2.7-5.2% and 7.1-8.1%, respectively. Urine samples could be directly subjected to analysis without any additional sample pretreatment. The proposed method was demonstrated an efficient, flexible and versatile extraction tool which is ideally suitable for online conjunction with chromatographic methods.

Preparation and study of a naproxen ion-selective electrode.

Naproxen membrane electrodes based on different plasticizers and quaternary ammonium salt tetraoctylammonium (S)-6-methoxy-α-methyl-2-naphthaleneacetate (NAP-TOA) were prepared. The electrode response to naproxen has the sensitivity of -59.2 mV decade(-1) over the linear range of 10(-4)-10(-1) mol L(-1) and limit of detection 1.80×10(-5) mol L(-1). This electrode has a response time 15-20s and can be used in the pH range 5.5-9.5. The selective coefficients were determined in relation to some organic and inorganic anions and excipients of pharmaceuticals. The notable property and attractive quality of the naproxen electrode are low cost, comfortable application and very long lifetime-about 20 months. The electrode was successfully applied for determination of naproxen in urine samples and pharmaceuticals by the calibration curve method and standard addition method. The obtained results are comparable and sometimes better than those obtained by pharmacopoeial method.