High-performance Liquid chromatography-UV Detection Research Articles

Carbohydrate-based quality consistency evaluation of Saposhnikoviae Radix

This study aims to evaluate the quality consistency of Saposhnikoviae Radix based on carbohydrates, and explore the potential of carbohydrates as the internal quality control indicators of Saposhnikoviae Radix. The total polysaccharides were quantified by UV-Vis spectrophotometry and the molecular weight range of the polysaccharides was determined by high performance gel-permeation chromatography-evaporative light scattering detection(HPGPC-ELSD). The monosaccharides in polysaccharides and the free monosaccharides were quantified by high performance liquid chromatography-UV detection(HPLC-UV), and the oligosaccharides and fructose were quantified by high performance liquid chromatography-evaporative light scattering detection(HPLC-ELSD). The carbohydrate-based quality of Saposhnikoviae Radix was compared among 45 batches of commercial samples and 13 batches of self-collected samples. The results showed that the molecular weight distribution, monosaccharide composition, oligosaccharide, and free monosaccharide composition were similar in the 58 batches of samples. The average content of total polysaccharides, oligosaccharides, and total free monosaccharides in commercial samples were 39.66, 148.79, and 68.62 mg·g~(-1), respectively. The content showed significant differences among batches, with the highest differences of 3.51, 1.75, and 2.58 times, respectively. The RSD of the relative ratios of monosaccharides in the polysaccharides in commercial samples reached 28%-45%. The average content of total polysaccharides, oligosaccharides, and total free monosaccharides in self-collected samples were 68.07, 145.76, and 42.04 mg·g~(-1), respectively, with the inter-region differences of 2.88, 1.88, and 1.07 times, respectively. The RSD of the relative ratios of monosaccharides in polysaccharides in self-collected samples ranged from 8.2% to 59%. The total polysaccharides and total free monosaccharides in self-collected samples were 1.72 times higher and 1.63 times lower, respectively, than those in commercial samples. The content of oligosaccharides was similar between self-collected samples and commercial samples. To sum up, carbohydrates are one of the material bases for the internal quality consistency of Saposhnikoviae Radix. The qualitative characteristics of polysaccharides and the quantitative characteristics of polysaccharides and oligosaccharides are related to the origin of medicinal materials. Moreover, the quantitative characteristics of polysaccharides and free monosaccharides may be related to the storage conditions. Carbohydrates are potential indicators for the quality control of Saposhnikoviae Radix and deserve attention.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (H3PW12O40). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME). The method was used for the extraction of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6- trichlorophenol from tap water, river water, and tea sample. The extracted target analytes were quantified via high-performance liquid chromatography-UV detection. The figures of merit of the method such as, linear dynamic ranges (LDRs), limit of detections (LODs) and, limit of quantifications (LOQs), were determined based on the obtained optimum condition. Based on the results, the LDR was between 1 and 500 μg L − 1 and r2 higher than 0.9960. The LODs and LOQs were obtained in the ranges of 0.28–0.36 µg L − 1 and 0.92–1.1 µg L − 1, respectively. The relative standard deviations ((RSDs% for inter-and intra-day) of the method for the extraction of target analytes were calculated in two different concentrations of (2 and 10 μg L − 1) and (5 and 10 μg L − 1) between 3.70% - 5.30% and 3.50% - 5.70%-respectively. The enrichment factors were obtained between 57 and 61. In order to investigate the accuracy of the method, also the relative recovery was obtained, between 93 and 105%. Finally, the proposed method was used for the extraction of the selected analytes in different water and tea samples.

Application of oxidized multi-walled carbon nanotubes and zeolite nanoparticles for simultaneous preconcentration of codeine and tramadol in saliva prior to HPLC determination

In this work, a dispersive micro-solid phase extraction technique along with high-performance liquid chromatography-UV detection was developed for simultaneous preconcentraion and determination of trace levels of codeine and tramadol in human saliva. This method is based on the adsorption of codeine and tramadol on a mixture of oxidized multi-walled carbon nanotubes and zeolite Y nanoparticles with 1:1 ratio as an efficient nanosorbent. Various analytical parameters influencing the adsorption step including the amount of adsorbent, the pH of the sample solution, the temperature, the stirring rate, the contact time of the sample solution, and the adsorption capacity were investigated. Based on the results, 10 mg adsorbent, sample solutions with pH = 7.6, temperature of 25 °C, stirring rate 750 rpm and contact time 15 min, in the adsorption step shows the best results for both drugs. Then the effective parameters on the analyte desorption stage such as the type of desorption solution, pH of the desorption solution, desorption time and desorption volume were investigated. Studies have shown that water/methanol (50:50 v/v) as desorption solution, pH = 2.0, desorption time of 5 min and desorption volume of 2 ml gives the best results.Chromatographic separation was performed on a RP-Shim-pack CLC-ODS-C18 column (250 mm × 4.6 mm, 5 µm) with isocratic mode. The mobile phase contained of acetonitrile:phosphate buffer (18:82, v/v) at pH = 4.5 and the flow rate was 1 ml.min−1. The wavelength of UV detector was adjusted at 210 nm and 198 nm for codeine and tramadol, respectively.Under optimum conditions, the extraction efficiencies of 98.5% and 99.2% were achieved for codeine and tramadol respectively. Enrichment factor of 13, detection limit of 0.3 μg L−1, relative standard deviation of 4.07 for codeine; and an enrichment factor of 15, a detection limit of 0.15 μg L−1, and standard deviation of 2.06 for tramadol were calculated. The linear range of the procedure for each drug was 1.0 to 1000 μg L−1. This method was successfully applied for the analysis of codeine and tramadol in saliva samples.

Effective solid-phase extraction of chlorophenols with covalent organic framework material as adsorbent

In this work, a porous extended network covalent organic framework designated as TP-NDA-COF was synthesized by the reaction of 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (TP) and 1,5-naphthalenediamine (NDA). The structure and morphology of the TP-NDA-COF was characterized by means of Fourier transform infrared spectra (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The TP-NDA-COF was applied as a solid-phase extraction adsorbent for the extraction of some chlorophenols from water and lemon black tea beverage samples prior to high performance liquid chromatography-UV detection. The main experimental parameters that affect the extraction efficiency including the type and volume of eluent, sample solution volume, sample loading rate and sample solution pH were investigated. Under the optimal conditions, the calibration curves were linear in the range of 0.30–60.0 ng mL−1 with the determination coefficients (R2) of 0.9996–0.9998 for water samples and in the range of 0.60–60.0 ng mL−1 with the R2 values from 0.9990 to 0.9996 for beverage samples. At the signal to noise ratio of 3 (S/N = 3), the method LODs for the analytes were 0.10–0.15 ng mL−1 for water samples and 0.20–0.50 ng mL−1 for lemon black tea beverage, respectively. Good repeatability was achieved with the relative standard deviations of less than 7%. The results showed that the SPE-HPLC method can be used for the determination of chlorophenols in environmental water and foodstuffs samples.

Calcium/Copper Alginate Framework Doped with CuO Nanoparticles as a Novel Adsorbent for Micro-extraction of Benzodiazepines from Human Serum

Background:Sample preparation is one of the most challenging phases in pharmaceutical analysis, especially in biological matrices, affecting the whole analytical methodology.Objective:In this study, a new Ca(II)/Cu(II)/alginate/CuO Nanoparticles Hydrogel Fiber (CCACHF) was synthesized through a simple, green procedure and applied for fiber micro solid-phase extraction (FMSPE) of diazepam (DIZ) and oxazepam (OXZ) as model drugs prior to high-performance liquid chromatography-UV detection (HPLC-UV).Methods:Composition and morphology of the prepared fiber were characterized and the effect of main parameters on the fiber fabrication and extraction efficiency have been studied and optimized.Results:In optimal conditions, calibration curves were linear, ranging between 0.1–500 μg L−1with regression coefficients of 0.9938 and 0.9968. Limit of Detection (LOD) (S/N=3) and Limit of Quantification (LOQ) (S/N=10) of the technique for DIZ and OXZ were 0.03 to 0.1 μg L−1. Within-day and between-day Relative Standard Deviations (RSDs) for DIZ and OXZ were 6.0–12.5% and 3.3–9.4%, respectively.Conclusion:The fabricated adsorbent has been substantially employed to the extraction of selected benzo-diazepines (BZDs) from human serum real specimens and the obtained recoveries were also satisfactory (82.1-109.7%).

Efficacy of Different Decontamination Processes in Mitigation of Pesticide Residues from Chili Crop

This study was conducted to evaluate the efficacy of seven decontamination processes in reducing the pesticide mixture load of six insecticides (quinalphos, profenophos, ethion, lambda-cyhalothrin, imidacloprid, and acetamiprid) from chili (Capsicum annuum L.). In the control treatment, the pesticide residues were extracted without following any decontamination procedure. The extraction of the insecticides from chili was initiated after 48 h of pesticide mixture spray and was done using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. The quantitative analysis of four insecticides, namely quinalphos, profenophos, ethion, and lambda-cyhalothrin, was done by coupled gas chromatography-electron capture detection and that of imidacloprid and acetamiprid by high-performance liquid chromatography-UV detection. The results depicted reduction of pesticide residues in all the decontamination treatments compared with the control, although it varied for different insecticides. Solutions of 1 and 5% NaCl and 5% CH3COOH served as efficient decontaminants in removal of quinalphos, profenophos, ethion, and lambda-cyhalothrin residues from chili to ca. 90%, whereas for imidacloprid and acetamiprid there was a mild decontamination only (33.33 to 52.44%). The solutions of 5% NaHCO3 and 0.01% KMnO4 were effective only in removing lambda-cyhalothrin residues from the chili crop, but for all other pesticides the decontamination was not much pronounced.

Evaluation and Optimization of a New Approach on Phenol Extraction from Real Water

Phenolic compounds are hazardous industrial wastes that can contaminate real water resources. Therefore, the removal of these compounds in order to reach acceptable levels before discharging becomes challenging. In this study, a combination method between dispersive liquid-liquid microextraction (DLLME) with high-performance liquid chromatography-UV detection at 280 nm with the isocratic condition was introduced as a new approach for separating phenol content in water samples. The optimized parameters that affect the extraction efficiency, such as type of solvents, the volume of extraction and dispersive, stirring speed of centrifuge and salt concentration were evaluated using response surface methodology (RSM). A central composite design (CCD) was used to investigate the effect of four independent variables parameters, as mentioned. The recovery value on the DLLME method for the water sample is in the range of 92.31 - 114.29%. Based on the recovery obtained, the DLMME-HPLC-UV is a promising method for phenol extraction because it is simple, effective and produce a high percentage of the recovery.

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%.

Quantification of anidulafungin and micafungin in human body fluids by high performance-liquid chromatography with UV-detection

The echinocandins anidulafungin (ANID) and micafungin (MICA) are recommended for treatment of invasive Candida infections. As target-site concentrations of antimicrobial agents are crucial for eradication of pathogens, we established and validated high-performance liquid chromatography-UV detection (HPLC-UV) assays for quantification of ANID and MICA in human plasma, ascites fluid, pleural effusion, and in cerebrospinal fluid (CSF). Sample pre-purification was performed by protein precipitation with acetonitrile followed by solid phase extraction. For both assays, intra- and interday precision, and accuracy fulfilled the requirements for bioanalytical methods issued by the European Medicine Agency (EMA). The lower limit of quantification was 0.01 mg/L for both drugs. At 25 °C, ANID and MICA concentrations declined by up to 70% within 24 h. Concentrations remained stable over 24 h at 4 °C and over four weeks at −80 °C. In conclusion, the developed methods are fit for the assessment of target-site pharmacokinetics of ANID and MICA in clinical studies.

A novel vortex-assisted liquid phase microextraction method for parabens in cosmetic oil products using deep eutectic solvent

ABSTRACTThe parabens, which are harmful to our bodies, are primarily utilized as preservatives in medicine, personal care products and cosmetics. A novel, more efficient, fast and cheap vortex-assisted liquid phase microextraction method based on deep eutectic solvents (DESs) was developed for the determination of parabens. The microextraction conditions were optimized using these solvents and the analytical parameters of the method were determined under optimal microextraction conditions. After extraction, the chromatographic separation of parabens was undertaken using high-performance liquid chromatography-UV detection. Experimental parameters, such as DES type, DES volume, dilution solvent volume and vortex extraction time were optimized. DES6 [ChCl-Ethylene glycol (1/2)] was the most suitable DES to work in this study. Detection limits for this method of 0.053 µg mL−1 for methylparaben, 0.061 µg mL−1 for ethylparaben, 0.049 µg mL−1 for propylparaben and 0.052 µg mL−1 for butylparaben were obtained. Correlation coefficients (R2) for a concentration range of 0.1–100 µg mL−1 were higher than 0.9992 and relative standard deviation (RSD) values below 2.91% at parabens concentration of 2.5 µg mL−1 were obtained. The results of spike/recovery values of real samples were greater than 84%. When compared with other methods, the main advantages include lower LOD, short extraction time, rapidity, repeatability and simplicity.

Development of a simple and rapid method for determination of trans, trans-Muconic Acid in human urine using PDLLME preconcentration and HPLC–UV detection

Benzene is a known human carcinogen and monitoring its exposure is very important. trans, trans-Muconic Acid (tt-MA) is an open-ring metabolite product proposed by related regulatory bodies as the best biomarker of benzene exposure. In this study, a new, simple and rapid method was developed for determination of tt-MA in a urine sample using partitioned dispersive liquid–liquid microextraction technique coupled with high-performance liquid chromatography–UV detection. Under the optimal condition, 2000 µL of tetrahydrofuran and 200 µL chloroform were used as disperser and extraction solvent, respectively, for 5 mL sample containing the target analyte. The method was linear in the range of 0.001–10 mg L−1. Method LOD, LOQ, relative standard deviation (RSD) for 3 days and under three concentrations and relative recovery were obtained 0.11 μg L−1, 0.83 µg L−1, 2.02–3.96% and 86–102%, respectively. Therefore, the proposed method with high recovery and easy application is recommended to be used to detect tt-MA in human urine samples.

Porous covalent triazine-terphenyl polymer as hydrophilic–lipophilic balanced sorbent for solid phase extraction of tetracyclines in animal derived foods

A novel hydrophilic–lipophilic balanced (HLB) solid phase extraction sorbent, microporous covalent triazine-terphenyl polymer (CTPCC-TP) was successfully synthesized and applied for the cleanup and extraction of tetracycline drugs in animal derived food samples. The specific ratio of two monomers, hydrophilic triazine and lipophilic aromatic rings, endowed the new material with hydrophilic–lipophilic balanced character, which made it capable of extracting both polar and nonpolar analytes. Prior to solid-phase extraction, food samples were extracted by McIlvaine buffer and passed through the CTPCC-TP cartridge. The experimental parameters affecting extraction efficiency, including loading, washing and elution were investigated and optimized. With the use of high-performance liquid chromatography-UV detection, a method detection limit in the range of 8.0–16.8 μg kg−1 and good linearity (22.6–1500 μg kg−1) for the determination of the tetracyclines in animal derived food samples can be achieved. The relative standard deviations (RSDs) for five replicate extractions of the tetracyclines ranged from 4.8 to 8.2%. The method recoveries for spiked tetracyclines (100 and 1000 μg kg−1) in bovine milk, egg, chicken liver samples were in the range of 81.3–98.7% with RSDs ranging from 3.9 to 7.7%, respectively, depending on both the analytes and samples. The method was suitable for the determination of tetracyclines in animal derived food samples.

Graphene Oxide-Based Dispersive-Solid Phase Extraction for Preconcentration and Determination of Ampicillin Sodium and Clindamycin Hydrochloride Antibiotics in Environmental Water Samples Followed by HPLC-UV Detection.

In this work, a reusable graphene oxide (GO) based dispersive-solid phase extraction (d-SPE) was synthesized and used for the analysis of trace ampicillin sodium (AMP) and clindamycin hydrochloride (CLI) in water samples followed by high performance liquid chromatography-UV detection (HPLC-UV). Batch experiments were conducted to investigate the effects of pH and volume of the sample solution, contact time, adsorption isotherms, temperature, and desorption conditions. The maximum adsorption capacities of AMP and CLI on GO nanosheets were found to be 33.33 mg g-1 and 47 mg g-1, respectively. The adsorption isotherm data can be well fitted by Temkin (AMP and CLI) and Freundlich (AMP), and the adsorption process followed the pseudo-second-order model. The thermodynamic parameters were calculated, indicated that the adsorption process of both analytes were spontaneous and exothermic. In addition, the d-SPE following HPLC analyses showed good linearity in the range of 0.5-200 ng mL-1 (R2= 0.999) for AMP and 1-200 ng mL-1 (R2= 0.999) for CLI, with LOD of 0.04 and 0.24 ng mL-1 for AMP and CLI, respectively. The percent of extraction recoveries, intra and inter-day precisions (expressed as RSD %, n = 3) were in the range of 96.4-101.6%, 2.2-3.0, and 3.7-4.7 for AMP as well as 94.2-98.6%, 2.2-3.8, and 3.5-4.6 for CLI, respectively. The preconcentration factor of 20 was achieved for both analytes. From these results, it can be concluded that the validated method is a simple, cost-effective and repeatable method for analysis of AMP and CLI in water samples and provide a new platform for antibiotics decontamination.

Impact of synthetic canine cerumen on in vitro penetration of auricular skin of dogs by florfenicol, terbinafine, and betamethasone acetate.

OBJECTIVE To determine the pharmacokinetics of florfenicol, terbinafine, and betamethasone acetate after topical application to canine auricular skin and the influence of synthetic canine cerumen on pharmacokinetics. SAMPLE Auricular skin from 6 euthanized shelter dogs (3 females and 3 neutered males with no visible signs of otitis externa). PROCEDURES Skin adjacent to the external opening of the ear canal was collected and prepared for use in a 2-compartment flow-through diffusion cell system to evaluate penetration of an otic gel containing florfenicol, terbinafine, and betamethasone acetate over a 24-hour period. Radiolabeled 14C-terbinafine hydrochloride and 3H-betamethasone acetate were added to the gel to determine dermal penetration and distribution. Florfenicol absorption was determined by use of high-performance liquid chromatography-UV detection. Additionally, the effect of synthetic canine cerumen on the pharmacokinetics of all compounds was evaluated. RESULTS During the 24-hour experiment, mean ± SD percentage absorption without the presence of synthetic canine cerumen was 0.28 ± 0.09% for 3H-betamethasone acetate, 0.06 ± 0.06% for florfenicol, and 0.06 ± 0.02% for 14C-terbinafine hydrochloride. Absorption profiles revealed no impact of synthetic canine cerumen on skin absorption for all 3 active compounds in the gel or on skin distribution of 3H-betamethasone acetate and 14C-terbinafine hydrochloride. CONCLUSIONS AND CLINICAL RELEVANCE 3H-betamethasone acetate, 14C-terbinafine hydrochloride, and florfenicol were all absorbed in vitro through healthy auricular skin specimens within the first 24 hours after topical application. Synthetic canine cerumen had no impact on dermal absorption in vitro, but it may serve as a temporary reservoir that prolongs the release of topical drugs.

Selective removal of 2,4-dichlorophenol and 2,4,6-trichlorophenol in aqueous solutions by polyaniline-modified magnetic nanoparticles using high-performance liquid chromatography-UV detection

Selective removal of 2,4-dichlorophenol and 2,4,6-trichlorophenol in aqueous solutions by polyaniline-modified magnetic nanoparticles using high-performance liquid chromatography-UV detection

Determination of cobalt(II), nickel(II) and palladium(II) Ions via fabric phase sorptive extraction in combination with high-performance liquid chromatography-UV detection

ABSTRACTA method for the determination of Co(II), Ni(II) and Pd(II) in aqueous samples by fabric phase sorptive extraction-high-performance liquid chromatography-UV detection (FPSE-HPLC-UV) is developed. A preconcentration step was necessary due to the trace level concentrations of these elements in aqueous samples. Sol-gel polytetrahydrofuran nanocomposite was selected as the sorbent. All major FPSE parameters were optimized. The limit of detection for Co(II), Ni(II) and Pd(II) morpholino dithiocarbamate complexes were found at much lower concentration level compared with earlier reported data with excellent reproducibility. The new FPSE-HPLC-UV method can be used for routine determination of these metal species in various aqueous environmental samples and in different alloys.

Development of Carbon Nanotube-Polyamide Nanocomposite-based Stir Bar Sorptive Extraction Coupled to HPLC-UV Applying Response Surface Methodology for the Analysis of Bisphenol A in Aqueous Samples.

A novel nanocomposite based on reinforcing of multiwalled carbon nanotubes in polyamide (PA) was prepared by solvent exchange method as stir bar coating. The morphology and surface characteristic of PA and CNT/PA coated stir bars were investigated using scanning electron microscopy. The stir bar coated by CNT/PA nanocomposite was used as an extraction device for stir bar sorptive extraction of bisphenol A from aqueous samples followed by high performance liquid chromatography-UV detection. The effect of CNTs doping level and oxidation of CNTs on the extraction capability of the coating was investigated. Response surface methodology applying central composite design was used for modeling and optimization of important factors influencing the extraction and desorption processes including extraction time, salt and methanol content, desorption solvent, its volume and desorption time. Limit of detection and linear dynamic range of the method were 0.3 ng mL-1 and 1-10 ng mL-1, respectively. The method precision (RSD%) with four replicate determinations was 4.9% for distilled water at the concentration level of 10 ng mL-1 The obtained RSD% for reproducibility of stir bars was 7.4%. The developed method was successfully applied to the bottled mineral water samples, while the relative recoveries (RR%) were obtained to be in the range of 92.0-101.9%.

Zinc oxide-copper oxide nanoplates composite as coating for solid phase microextraction combined with high performance liquid chromatography-UV detection for trace analysis of chlorophenols in water and tomato juice samples.

In the present research, the ZnO-CuO nanoplate composite (ZCNC), solid-phase microextraction (SPME) fiber coating, was prepared and its extraction capability for certain chlorophenols (CPs) was studied through directly sampling the typical CPs mixed standard solution of 4-chlorophenol, 2,3-dichlorophenol, 2,5-dichlorophenol, and 2,4,6-trichlorophenol with high performance liquid chromatography. ZCNC thickness was in the range of 50-65nm. The effective variables on ZCNC-SPME extraction efficiency were extraction time, salt percentage, and desorption time. Accordingly, a multivariate strategy was applied based on an experimental design by using central composite design for optimizing the significant factors affecting the extraction efficiency. The detection limit and relative standard deviation (RSD) (n = 6), that include repeatability and reproducibility as the target analytes, were in the range of 0.5-5ngml(-1) and 5.1-14% of standard solutions at 50ngml(-1) concentration of CPs, respectively. The developed technique is believed to be successfully applicable to preconcentration and determination of target analytes in environmental water and tomato juice samples. Graphical Abstract Application of zinc oxide-copper oxide nanoplates composite for extraction of chlorophenols in water and tomato juice samples and optimizing condition by experimental design method.

Application of Air-Assisted Liquid-Liquid Microextraction for Determination of Some Fluoroquinolones in Milk Powder and Egg Samples: Comparison with Conventional Dispersive Liquid-Liquid Microextraction

Herein, an air-assisted liquid-liquid microextraction (AALLME) has been described and compared to conventional dispersive liquid-liquid microextraction (DLLME) for the extraction/preconcentration of six fluoroquinolone compounds in milk powder and egg samples prior to high-performance liquid chromatography-UV detection (HPLC-UV). In order to compare the novel AALLME technique to the conventional DLLME technique, several parameters that influence the extraction efficiency were studied and optimized. Both methods have been validated for milk powder and egg analysis, obtaining limits of quantification lower than those usually permitted by legislation in food matrices, with precisions expressed as coefficients of variation lower than 8 % and recoveries between 72 and 115 % which were acceptable recoveries and repeatability. An AALLME method needs less organic solvent and shorter centrifugation time; therefore, it is more environmentally friendly and efficiently compared to DLLME.

Fast separation and quantification of three anti-glaucoma drugs by high-performance liquid chromatography UV detection

In this study, a simple and accurate high-performance liquid chromatography method was developed and validated for fast separation of three anti-glaucoma drugs: timolol maleate (TM), brimonidine tartrate (BM), and latanoprost (LP). Separation of the three drugs was achieved in < 6 minutes using a BDS Hypersil phenyl column and a mobile phase consisting of acetonitrile: 25mM phosphate buffer, pH 4.0 (50: 50, v/v) at 1.2 mL/min with UV detection at 210 nm. The method was linear over the concentration ranges of 5.0–200.0 μg/mL, 2.0–80.0 μg/mL and 1.0–25.0 μg/mL with lower detection limits of 0.21 μg/mL, 0.10 μg/mL and 0.11 μg/mL for TM, BM and LP, respectively. The method was applied for the determination of two fixed-dose combination eye drops for the treatment of glaucoma, containing TM together with either BM or LP. Commercial samples of single-ingredient ophthalmic solutions containing the studied drugs were also successfully analyzed. The results obtained by the proposed method were favorably compared with those obtained by the comparison methods using Student's t test and the variance ratio F test.