Development of a highly efficient in-tube solid-phase microextraction system coupled with UHPLC-MS/MS for analyzing trace hydroxyl polycyclic aromatic hydrocarbons in biological samples

Hydroxyl polycyclic aromatic hydrocarbons are considered active mutagenic and carcinogenic substances and are found in extremely low levels (ng/g) in biological samples. As a result, their determination in urine and blood samples is challenging, and a sensitive and effective method for the analysis of trace hydroxyl polycyclic aromatic hydrocarbons in complex biological matrices is required. In this work, a novel macroporous in-tube solid-phase microextraction monolith was prepared via a thiol-yne click reaction, and a highly efficient analytical method based on in-tube solid-phase microextraction coupled with UHPLC-MS/MS was developed to determine hydroxyl polycyclic aromatic hydrocarbons with low detection limits of 0.137–11.0 ng/L in complex biological samples. Four hydroxyl polycyclic aromatic hydrocarbons, namely, 2-hydroxyanthraquinone, 1-hydroxypyrene, 1,8-dihydroxyanthraquinone, and 6-hydroxychrysene, were determined in the urine samples of smokers, non-smokers, and whole blood samples of mice. Satisfactory recoveries were achieved in the range of 83.1–113% with relative standard deviations of 3.2–9.7%. It was found that implementation of the macroporous monolith gave a highly efficient approach for enriching trace hydroxyl polycyclic aromatic hydrocarbons in biological samples.     

Poly(methacrylic acid‐ethylene glycol dimethacrylate‐N‐vinylcarbazole) monolithic column for the enrichment of trace benzodiazepines from urine and beer samples

A sensitive microextraction method based on a new poly(methacrylic acid‐ethylene glycol dimethacrylate‐N‐vinylcarbazole) monolithic capillary column, coupled with gas chromatography and electron capture detection, was established for the determination of three benzodiazepines (estazolam, alprazolam, and triazolam) in urine and beer samples. Owing to the abundant π electrons and polar surface of N‐vinylcarbazole, N‐vinylcarbazole‐incorporated monolith showed a higher extraction performance than neat poly(methacrylic acid‐ethylene glycol dimethacrylate) because of the enhanced π–π stacking interactions derived from the π‐electron‐rich benzene groups from N‐vinylcarbazole. The monolith exhibited a homogeneous and continuous structure, good permeability, and a long lifetime. Factors affecting the extraction such as solution pH, salt concentration, sample volume, desorption solvent, and desorption volume were investigated. Under the optimized conditions, limits of detection of 0.011–0.026 ng/mL were obtained. The one‐column and column‐to‐column precision values were ≤7.2 and ≤9.8%, respectively. The real samples were first diluted with deionized water and then treated by the monolith microextraction before gas chromatography analysis. The recoveries were 81.4–93.3 and 83.3–94.7% for the spiked samples, with relative standard deviations of 4.1–8.1 and 3.8–8.5%, respectively. This method provides an accurate, simple, and sensitive detection platform for drug analysis.     

Automated on-line HPLC-HRGC: Instrumental aspects and application for the determination of heroin metabolites in urine

A fully automated on-line HPLC-HRGC instrument is described. Samples are loaded into an HPLC autosampler. Pre-separation is carried out, automatically transferring the previously determined HPLC fraction to GC. Total HPLC fractions are introduced into GC, using the on-column or the loop-type interface, depending on the solvent evaporation technique applied. The HPLC column is automatically backflushed with a suitable solvent during GC analysis. The instrument was used for analyzing heroin metabolites, particularly morphine, in urine samples. Raw urine extracts were injected into HPLC and analyzed by GC using FID.     

Hollow fiber liquid-phase microextraction for the determination of trace amounts of rosiglitazone (anti-diabetic drug) in biological fluids using capillary electrophoresis and high performance liquid chromatographic methods

A three-phase hollow fiber liquid-phase microextraction (HF-LPME) coupled either with capillary electrophoresis (CE) or high performance liquid chromatography (HPLC) with UV detection methods was successfully developed for the determination of trace levels of the anti-diabetic drug, rosiglitazone (ROSI) in biological fluids. The analyte was extracted into dihexyl ether that was immobilized in the wall pores of a porous hollow fiber from 10 mL of aqueous sample, pH 9.5 (donor phase), and was back extracted into the acceptor phase that contained 0.1 M HCl located in the lumen of the hollow fiber. Parameters affecting the extraction process such as type of extraction solvent, HCl concentration, donor phase pH, extraction time, stirring speed, and salt addition were studied and optimized. Under the optimized conditions (extraction solvent, dihexyl ether; donor phase pH, 9.5; acceptor phase, 0.1 M HCl; stirring speed, 600 rpm; extraction time, 30 min; without addition of salt), enrichment factor of 280 was obtained. Good linearity and correlation coefficients of the analyte was obtained over the concentration ranges of 1.0–500 and 5.0–500 ng mL⁻¹ for the HPLC (r² = 0.9988) and CE (r² = 0.9967) methods, respectively. The limits of detection (LOD) and limits of quantitation (LOQ) for the HPLC and CE methods were (0.18, 2.83) and (0.56, 5.00) ng mL⁻¹, respectively. The percent relative standard deviation (n = 6) for the extraction and determination of three concentration levels (10, 250, 500 ng mL⁻¹) of ROSI using the HPLC and CE methods were less than 10.9% and 13.2%, respectively. The developed methods are simple, rapid, sensitive and are suitable for the determination of trace amounts of ROSI in biological fluids.     

Three-phase system in solvent bar microextraction: An approach for the sample preparation of ionizable organic compounds prior to liquid chromatography

In this article, a simple new solvent microextraction technique is described for the extraction of ionizable organic compounds. This involves performing simultaneous forward- and back-extraction across an organic film immobilized in the pores of a porous polypropylene hollow fiber. Four chlorophenoxyacetic acid herbicides were chosen as model compounds. The target compounds are extracted from the stirred acidic aqueous sample (adjusted to 0.5 M HCl; donor phase) through a thin film of an organic solvent residing in the pores of a polypropylene hollow fiber; they are then finally extracted into another alkaline aqueous phase (1 M NaOH; acceptor phase). Both ends of the fiber are pressure-sealed. The acceptor phase was analyzed by liquid chromatography (LC). This method gave good enrichment (by a factor of 438-553) of the analytes in 40 min extraction time with reasonably good reproducibility. The analytical potential of the method was demonstrated by applying the method to spiked river water sample.     

Comparative analysis of adaptive neuro-fuzzy inference system (ANFIS) and RSRM models to predict DBP (trihalomethanes) levels in the water treatment plant

Since disinfection by-products are a growing concern, it is important to know their quantities in water treatment plants before they are released to the public. As a result, there is a requirement for constant monitoring of disinfection by-products (DBPs), which can have major consequences for human health and productivity. Consequently, in previous studies, several models for predicting disinfection byproduct formation in drinking water have been developed which were either linear/log-linear, hybrid or neural network (radial basis function). In this study, an adaptive neuro-fuzzy inference system (ANFIS) is proposed for predicting trihalomethane levels in real distribution systems. To train and verify the proposed model, 24 sets of data were used, including THMs levels (TCM, BDCM, DBCM and T-THM levels) and five parameters (pH, temperature, UVA₂₅₄, residual chlorine, and dissolved organic carbon). As compared to response surface modeling (RSRM) coefficient of determination, R² is between 0.727 < R² < 0.886, average absolute deviation, AAD = 4.07–10.99 %), MAE = 0.01 – 0.978, and RMSE = 0.017 – 1.449. Further, ANFIS for THMs (T-THMs, TCM, BDCM, and DBCM) prediction consistently show higher regression coefficients between 0.956 < R² < 0.989, average absolute deviation, AAD = 0.350 – 1.977 %), MAE = 0.002 – 0.133, and RMSE = 0.007 – 0.401, Consequently, based on the statistical indices obtained, ANFIS, on the other hand, proved to be effective for predicting the formation of THMs, and thus allowed improved DBPs monitoring in water treatment systems.     

New developments in the extraction and determination of parabens in cosmetics and environmental samples. A review

Parabens are a family of synthetic esters of p-hydroxibenzoic acid widely used as preservatives in cosmetics and health-care products, among other daily-use commodities. Recently, their potential endocrine disrupting effects have raised concerns about their safety and their potential effects as emerging pollutants, leading to the regulation of the presence of parabens in commercial products by national and trans-national organizations. Also, this has led to an interest in developing sensible and reliable methods for their determination in environmental samples, cosmetics and health-care products.     

Preparation of magnetic poly(vinylimidazole‐co‐divinylbenzene) nanoparticles and their application in the trace analysis of fluoroquinolones in environmental water samples

Nanosized spherical magnetic poly(vinylimidazole‐co‐divinylbenzene) particles were synthesized and used as a sorbent for the enrichment of trace fluoroquinolones (FQs) from environmental water samples. A suspension polymerization procedure was used to prepare the sorbent. The magnetic sorbent was characterized by SEM, transmission electron microscopy, elemental analysis, and FTIR spectroscopy. Analysis of enrofloxacin, marbofloxacin, fleroxacin, lomefloxacin, and sparfloxacin in environmental water samples by the combination of the magnetic sorbent and HPLC with diode array detection was selected as a paradigm for the practical application of the new adsorbent. Several extraction conditions, including desorption solvent, extraction and desorption time, pH value, and ionic strength in sample matrix, were optimized. Results showed that the new sorbent had high affinity for FQs and could be used to extract them effectively. Under the optimum conditions, low detection (S/N = 3) and quantification (S/N = 10) limits were achieved for the target analytes, within the ranges of 0.20–1.46 and 0.68–4.84 μg/L, respectively. Method repeatability was achieved in terms of intra‐ and interday precisions, indicated by the RSDs, which were both <10.0%. The method also showed good linearity, simplicity, practicality, and environmental friendliness for the extraction of FQs. Finally, the developed method was successfully applied to the determination of FQs in lake water, surface water, and reservoir water samples. Acceptable recoveries of spiked target compounds in these water samples were in the range of 52.1–104.5%.     

A microscale HPLC‐UV method for the determination of latamoxef in plasma: An adapted method for therapeutic drug monitoring in neonates

Latamoxef, a broad‐spectrum anti‐bacterial agent of the β‐lactam antibiotics, is used off‐label in treatment of neonatal sepsis. Large inter‐individual variability and uncertainty of treatment make therapeutic drug monitoring (TDM) useful to optimize antimicrobial therapy. The objective of this study was to develop and validate a simple, selective and reliable HPLC method for the determination of latamoxef in small volumes of plasma, which could be used in neonatal TDM. After a simple protein precipitation, analytes were separated with liquid chromatography and quantified by UV detection, with tinidazole as the internal standard. The calibration range was linear from 3.0 to 60.0 μg/mL. Intra‐ and inter‐day precisions were < 7.2%. The acceptance criteria of accuracy (between 85 and 115%, 120% for lower limit of quantification) were met in all cases. A plasma volume of 50 μL was required to achieve the limit of quantification of 3.0 μg/mL. The TDM results showed a large variability in trough concentrations. A large number of patients were underdosed, highlighting the unmet need for TDM to optimize latamoxef therapy in neonates.     

Resonance Rayleigh scattering determination of trace amounts of Al in natural waters and biological samples based on the formation of an Al(III)-morin-surfactant complex

A novel method for the determination of trace amounts of Al(III) based on resonance Rayleigh scattering (RRS) has been developed. In the presence of some surfactants, Al(III) can react with morin and form an Al(III)-morin-surfactant complex, which results in the enhancement of RRS intensity and the appearance of the corresponding RRS spectral characteristics. Their maximum scatter peaks are at 476 nm for the cetyltrimethylammonium bromide (CTAB) system, 489 nm for the cetylpyridinium chloride (CPC) system, 474 nm for the Triton X-100 system, and 473 nm for the Tween-20 system. The enhanced RRS intensity is directly proportional to the concentration of Al(III). The detection limits are in the range of (0.50-1.2)×10⁻⁷ mol l⁻¹ depending on the surfactant. The characteristics of RRS spectra of the complexes, the optimum conditions of these reactions and the influencing factors have been investigated. The method has high selectivity, and was successfully applied to the determination of Al(III) in natural and biological samples. Furthermore, according to different complexation capacity of Al(III)-morin-CTAB system under two pH conditions, speciation analysis of Al(III) in natural waters was explored. The labile monomeric Al fraction (mainly inorganic Al, Al_i) is determined at acidic pH and the total monomeric Al fraction (Al_a) is determined at alkaline pH. The results are in agreement with those obtained by Driscoll’s 8-hydroxyquinoline extraction-ion exchange method.     

An inimitable and ecological pleasant technique for the assessment of trace amount of copper (II) in tangible samples with new complexing reagent

A simple and rapid spectrophotometric technique has been designed for the trace copper analysis employing 1-(2-Thiazolylazo)-2-naphthol (TAN) reagent in aqueous micellar solution of cetyl trimethylammonium bromide (CTAB) as a surfactant. Copper complexed with 1-(2-Thiazolylazo)-2-naphthol to form bis[1-(2-Thiazolylazo)-2-naphthol]copper. The present spectrophotometric technique was very important since the micellar system was used in place of the toxic, high cost and time-consuming solvent extraction steps. The technique showed an enhanced detection efficiency, specificity, and molar absorptivity. It was found that the molar absorption coefficient and sensitivity of Sandel were ε 2.45 × 10⁴ L mol^?1cm^?1 and 2.6 ngcm^?2 at λ_max 578.4 nm. A linear calibration plot in the range 0.12–5.0 μg mL^?1 was obtained; a stoichiometric metal ligand ratio [M:L] of 1:2 was found for the formation of Cu-[TAN]₂. The complex was formed at pH 9.5 and was stable up to 24 h. The proposed technique has been employed to study copper from different alloys, biological, environmental and pharmaceutical samples.     

An ion imprinted electrochemical sensor based on flower-like gold nanoparticles for the detection of trace arsenic(III) ions in water and food samples

A selective and sensitive electrode based on Au−S bonds between As(III) ion-imprinted polymer (IIP) and the flower-like gold nanoparticles (FL-AuNPs) had been rationally developed for detecting As(III) by using the square wave voltammetry (SWV) method. Under optimized measurement conditions, the prepared electrochemical sensor exhibited obvious detection performance of As(III) in the range of 0.009 μg/L–0.50 μg/L with a relatively low detection limit of 0.015 μg/L. Furthermore, the imprinted electrochemical sensor displayed good reusability, excellent specificity, and demonstrated high potential for environmental control with a recovery rate between 80.7 % and 113.3 %.     

Preparation of a new Cu(II)-imprinted polymer and its application for the determination of trace copper in water samples by flame atomic absorption spectrometry

A new Cu(II)-imprinted polymer has been prepared for selective solid-phase extraction of Cu(II) prior to its determination by flame atomic absorption spectrometry. Two functional monomers, 4-(methacryloylamino)benzamide and 4-vinylpyridine, formed a complex with Cu(II) ion through coordination interactions. The self-assembled Cu(II)-monomer complex was copolymerised via bulk polymerisation method in the presence of ethyleneglycoldimethacrylate cross-linker. In order to remove Cu(II) ions, the resulting polymer was washed with 1.0 M HNO₃ and then with water until obtaining a neutral pH. The ion imprinted polymer was characterised by Fourier transform infrared. The experimental conditions were optimised for solid-phase extraction of Cu(II) using a column of ion-imprinted polymer (IIP). Quantitative retention was achieved between pH 5.0 and 7.0, whereas the maximum recovery for the non-imprinted polymer (NIP) was about 74% at pH 7.0. The IIP showed higher selectivity to Cu(II) in comparison to the NIP. The IIP also exhibited excellent selectivity for Cu(II) in the presence of other metal ions. The relative standard deviation and limit of detection (3s) of the method were 1.6% and 1.8 µg L^?1, respectively. The method was verified by analysis of two certified reference materials (CWW-TM-D and SRM 3280) and then applied to the determination of Cu(II) in seawater and lake water samples and haemodialysis concentrates.     

Construction of a portable sample preparation device with a magnetic poly(methacrylic acid‐co‐ethylene dimethacrylate) monolith as the extraction medium and its application in the enrichment of UV filters in water samples

A portable sample preparation device with a magnetic polymer monolith as the extraction medium was constructed. The monolith was synthesized by polymerizing methacrylic acid and ethylene dimethacrylate around a cylindrical magnet. In this way, the monolith with a magnetic core could be readily attached to the extraction device by magnetism. The constructed device was evaluated for the enrichment of UV filters in water samples, followed by high‐performance liquid chromatographic analysis. The extraction efficiency for the targets was satisfactory with no matrix interference. Good linearities were obtained for the UV filters with the correlation coefficients >0.9986. The limits of detection and quantification for the UV filters were 0.3–0.8 and 1.0–2.4 ng/mL, respectively. The recoveries of the UV filters from the spiked water samples at the concentration of 100 ng/mL were 95.3–101.7%, with relative standard deviations <10%. Accordingly, the proposed portable device was demonstrated to be suitable for on‐site simultaneous sampling, purification, and preconcentration within a single step.     

Biomimetic enhanced chemiluminescence of luminol-H2O2 system by manganese (III) deuteroporphyrin and its application in flow injection determination of phenol at trace level

A novel, sensitive and high selective flow-injection chemiluminescence (FI-CL) method for the determination of phenol is reported, based upon its decreasing effect on the CL reaction of luminol with hydrogen peroxide catalyzed by manganese (III) deuteroporphyrin [MnDP, Scheme 1, 3] in alkaline solution. Under the selected optimized experimental conditions, the relative CL intensity was linear with phenol in the range of 4.0 × 10⁻⁹ to 4.0 × 10⁻⁷ g mL⁻¹. The detection limit (3σ) was 6.3 × 10⁻¹⁰ g mL⁻¹ and the relative standard deviation for 1.0 × 10⁻⁷ g mL⁻¹ phenol (n = 11) was 2.99%. The regression equation was I = 120.79 + 1.14 × 1010c (R = 0.9936). This method has been applied to the determination of phenol in water with satisfactory results.     

A chelating resin with bis[2-(2-benzothiazolylthioethyl)sulfoxide]: Synthesis, characterization and properties for the removal of trace heavy metal ion in water samples

A new chelating resin containing bis[2-(2-benzothiazolylthioethyl)sulfoxide] was synthesized using chloromethylated polystyrene as material and characterized by elemental analysis and infrared spectra. The adsorption capacities of the newly formed resin for Hg²⁺, Ag⁺, Cu²⁺, Zn²⁺, Pb²⁺, Mn²⁺, Ni²⁺, Cd²⁺ and Fe³⁺ were investigated over the pH range 1.0-6.0. The resin exhibited no affinity for alkali or alkaline earth metal ions. The maximum adsorption capacities of the resin for Hg²⁺, Ag⁺, Cu²⁺, Zn²⁺, Pb²⁺, Mn²⁺, Ni²⁺, Cd²⁺ and Fe³⁺ were 1.49, 0.96, 0.58, 0.11, 0.37, 0, 0.24, 0.36 and 0.25 mmol g⁻¹, respectively. In column operation it had been observed that Hg²⁺ and Ag⁺ in trace quantity could be separated from different binary mixtures and Hg²⁺ could be effectively removed from industrial wastewater and the natural water spiked with Hg²⁺ at usual pH.     

An inorganic phosphate (Pi) sensor triggers ‘turn-on’ fluorescence response by removal of a Cu ion from a Cu-ligand sensor: determination of Pi in biological samples

A fluorescent ligand that displays a high selectivity for Cu²⁺ has been synthesized. On complexation with Cu²⁺, the fluorescence of the ligand is quenched. Inorganic phosphate ions decomplex Cu²⁺ displaying a fluorescence enhancement that can even be seen with naked eyes. The method was successfully used in quantitative determination of inorganic phosphates in serum, urine, and saliva samples.     

HPLC-AAS hybrid technique for studying the speciation of trace metals (Al,Fe, Si,Hg) in biological fluids: A review of applications,recent experiences and perspectives

A method developed using the combination of HPLC and AAS enabling both qualitative and quantitative study of the protein binding and speciation of trace metals in biological fluids at clinical relevant levels is reviewed. The whole system was made metal-free by using polymer-based columns, column holders and tubing and by the insertion of a silica-based scavenger column placed immediately before the injection valve to selectively retain any trace of aluminum and iron originating from buffer solutions and recipients. ETAAS instrumental conditions were carefully selected to eliminate interferences secondary to the salt gradient elution. Particular attention was paid to the choice of HPLC columns. Protein recoveries varied between 95 and 105% and trace metal recoveries were close to 100%. Intra-assay and inter-assay CVs of the HPLC/AAS hybrid technique were below 10%. Because of its high sensitivity, the method can be used at clinically relevant concentrations and was applied successfully to study (i) the interaction between iron and aluminum for binding to transferrin, (ii) the influence of citrate on the transferrin binding of aluminum, (iii) the speciation of silicon in the serum of dialysis patients and (iv) the toxicity of mercury compounds in cell cultures.     

Complex formation of cetirizine drug with bivalent transition metal(II) ions in the presence of alanine: synthesis,characterization, equilibrium studies,and biological activity studies

Mononuclear cobalt(II), nickel(II), and copper(II) complexes of cetirizine·2HCl (CTZ = 2-[2-[4-[(4-chlorophenyl)phenyl methyl]piperazine-1-yl]-ethoxy]acetic acid) in the presence of alanine (Ala) as a representative example of amino acids were synthesized and elucidated by different physical techniques. All complexes have been characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments, and spectroscopic data. The measured molar conductance values in DMSO indicate that the complexes are nonelectrolytes. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of complexes. The metal–oxygen bond length in the synthesized complexes obeys the order M–OH₂ > M–O_CTZ > M–O_Ala. Formation equilibria of the ternary complexes have been investigated. Ternary complexes are formed by a simultaneous mechanism. Stoichiometry and stability constants for the complexes formed are reported. The concentration distributions of various species formed in solution were also evaluated as a function of pH. CTZ and its metal chelates have been screened for their antimicrobial activities against some selected types of gram-positive (G⁺) and gram-negative (G^?) bacteria. They were more active against (G⁺) than (G^?) bacteria.     

Quantification of 1‐(propan‐2‐ylamino)‐4‐propoxy‐9H‐thioxanthen‐9‐one (TX5), a newly synthetized P‐glycoprotein inducer/activator,in biological samples: method development and validation

A simple, rapid and economical method was developed and validated for the analysis and quantification of 1‐(propan‐2‐ylamino)‐4‐propoxy‐9H ‐thioxanthen‐9‐one (TX5), a P‐glycoprotein inducer/activator, in biological samples, using reverse‐phase high‐performance liquid chromatography (HPLC). A C₁₈ column and a mobile phase composed of methanol–water (90/10, v /v) with 1% (v/v) triethylamine, at a flow rate of 1 mL/min, were used for chromatographic separation. TX5 standards (0.5–150 μm ) were prepared in human serum. Methanol was used for TX5 extraction and serum protein precipitation. After filtration, samples were injected into the HPLC apparatus and TX5 was quantified by a conventional UV detector at 255 nm. The TX5 retention time was 13 min in this isocratic system. The method was validated according to ICH guidelines for specificity/selectivity, linearity, accuracy, precision, limits of detection and quantification (LOD and LOQ) and recovery. The method was proved to be selective, as there were no interferences of endogenous compounds with the same retention time of TX5. Also, the developed method was linear (r ² ≥ 0.99) for TX5 concentrations between 0.5 and 150 μm and the LOD and LOQ were 0.08 and 0.23 μm , respectively. The results indicated that the reported method could meet the requirements for TX5 analysis in the trace amounts expected to be present in biological samples.