Simultaneous Determination Of Trace Amounts Research Articles

A simple optical sensor for the simultaneous determination of trace amounts of silver and gold nanoparticles in water by cloud point microextraction

Nowadays, metal nanoparticles are widely used in many fields due to their excellent properties. This has led to an increasing presence of these species in water, which, although in very low concentrations, can cause damage to ecosystems. These nanomaterials are currently considered as emerging pollutants in water, so there is a need to know their concentrations. In particular, gold and silver nanoparticles are among the most widely used. Therefore, the development of simple methods that allow their determination even at trace concentrations is of interest. In this work, a method has been developed for the simultaneous determination of low concentrations of silver and gold nanoparticles (AgNPs and AuNPs, respectively) in water by cloud point microextraction using Triton X-114 as extractant and UV–Vis molecular spectrophotometry. It is a simple, environmentally friendly method with an easy-to-use portable instrument that requires only a microdrop of the extracted phase for the analysis of both species. Detection limits reached were 17 and 15 µg L−1 for AgNPs and AuNPs, respectively. The enrichment factors were 160 for AgNPs and 165 for AuNPs.

A new chemometrically optimised HPLC method for the simultaneous determination of imatinib mesylate and capecitabine, the active medicinal components

ABSTRACT Anticancer drugs such as imatinib mesylate (IMP) and capecitabine (CAP) and their metabolites enter the water cycle through wastewater treatment plant effluents or directly into the water cycle due to their limited biodegradability in typical wastewater treatment plants. However, their long-term effects on water resources are unknown due to their toxicity. The hazards concerned with chronic exposure to these substances raise concerns about their impact on organisms, environmental safety and biodiversity conservation. Therefore, in this study, a chemometrically optimised HPLC method was developed for the simultaneous determination of trace amounts of cytotoxic agents IMP and CAP used in cancer treatment in environmental water, synthetic urine samples and drug samples. Using the Box-Behnken design, optimum conditions discovered using the traditional method were optimised. The effect of each element was evaluated in the design by four factors based on HPLC determination. For the examined levels, mobile phase 1, mobile phase 2 ratio, flow rate, and column temperature parameters for the HPLC method were determined. Using regression analysis on the experimental results, the factors influencing resolution were identified. To achieve the reliability of the results, the Analysis of Variance (ANOVA) test was used. The ANOVA test was employed to verify the consistency of the data. With the information gathered, a model was developed. HPLC was used to examine the target chemicals. A good linearity (R2 > 0.99) was established for the IMP and CAP in the concentration ranges of 1.18–23.59 µg mL−1 and 0.76–15.09 µg mL−1, respectively, under optimum circumstances. The recoveries for spiked samples at three concentration levels ranged from 98.31 to 101.11. The created method has been applied to synthetic urine samples, regional environmental water samples, and pharmaceutical samples with success.

Simultaneous determination of trace amounts of dopamine and uric acid in human plasma samples with novel voltammetric biosensor (GCE/Ppy/DEA MIP) following the thin film-µSPE method based on electrospun nanofibers

In order to achieve the aim of this study, i.e., simultaneous measurement of trace amounts of dopamine (DA) and uric acid (UA) following their preconcentration, a novel sorbent with high performance was prepared. Hence, herein, poly vinyl chloride/Mg-Al layered double hydroxide (PVC/Mg-Al LDH) electrospun nanofibers were synthesized for the thin film- micro solid phase extraction (TF-µSPE) and then, simultaneous extraction of trace amounts of DA and UA was done. Finally, DA and UA were determined simultaneously from two different human plasma samples; afterwards, glassy carbon electrode/Poly pyrrole/diethylamine (DA, UA) molecularly- imprinted polymer (GCE/Ppy/DEA (DA, UA) MIP) electrochemical biosensor was constructed. The synthesis confirmation of PVC-Mg-Al LDH electrospun nanofibers was accomplished by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and attenuated total reflection-Fourier transform infrared (ATR-FTIR). In addition, the GCE/Ppy/DEA MIP and GCE/Ppy/DEA (non-imprinted polymer) NIP nanocomposites were characterized with field emission-scanning electron microscopy (FE-SEM). PVC, as a polymer with a large surface area and high porosity, is an appropriate candidate in the sorbent preparation process with electrospinning. The flexible interlayer region is accessible to various anionic and polar molecular species. Adding Mg-Al LDH led to an extensive surface area of electrospun nanofibers. In the case of Ppy and DEA MIP as GCE surface modifiers, Ppy increased the electroactive sites, leading to the high conductivity of the electrochemical biosensor. Besides, DEA MIP has high selectivity and sensitivity. Optimization of impressive factors on the extraction procedure was conducted by one at-time (OAT) method, and optimum conditions for the construction of electrochemical biosensor were attained with experimental design (design-expert 12.0 software). According to the optimum conditions, the wide linear range was obtained 76.6–268.1 µg mL−1 for DA and 84.1–378.2 µg mL−1 for UA with R2≥ 0.96, low detection limits ranged from 22.3 µg mL–1 for DA and 24.8 µg mL−1 for UA based on S/N = 3 and large enrichment factors. The intra-day (n = 3) and inter-day (n = 3) RSDs% were obtained in the span of 5.3% − 6.1% for DA and 4.0% − 5.6% for UA. Eventually, the efficiency of the TF-µSPE-voltammetric biosensor method was evaluated for the measuring of DA and UA in human plasma samples with satisfactory recoveries (90.2%–99.7%).

A new microfluidic-chip device followed by sensitive image analysis of smart phone for simultaneous determination of dyes with different acidic–basic properties

In this study, a new microfluidic-chip coupled with micro solid phase extraction (μ-SPE) and a RGB detection system was designed. The method was used for extraction and simultaneous determination of trace amounts of dyes with different acidic–basic properties. Erythrosine (Ery) and Crystal Violet (CV) were selected as acidic and basic model analytes, respectively. The first step of this method is based on the on-chip electromembrane extraction (CEME) of analytes from aqueous solution. The utilized microfluidic system is a single compartment that composed of three polymethyl metacrylate plates (with sandwiched structures) patterned with palm shaped helix channels. The device consisted one pair of platinum electrodes that were embedded in the acceptor phase channels in each side. The middle part was cut and used as the path of the sample. The extracted analytes by CEME were passed through the micro-packed column containing strong cation and anion exchanger sorbents respectively. Two adsorbents were separated by a polypropylene frit and sealed on each side by two polypropylene frites. Following dye adsorption on the sorbents, the colors that emerged were promptly evaluated using RGB colorimetry on a smartphone. Central composite design was used to analyze and optimize the effective parameters on extraction efficiency. The relative standard deviations (RSDs%) based on five replicate measurements were less than 7.8% for RGB and 8.6% for the spectrophotometry technique under ideal conditions. Image analysis using a smartphone yielded LOD values of 15.0 and 10.5 μg L−1 for Ery and CV, respectively. The CEME- μ-SPE -RGB approach produced findings that were equivalent to those obtained by spectrophotometry. Finally, the approach was used to accurately determine Ery and CV in water samples, yielding good relative recoveries (recovery ≥94.0).

Simultaneous Determination of Cationic and Anionic Surfactants in Environmental Water Samples by Ion-Pair Liquid Chromatography/Mass Spectrometry

Background: Cationic surfactants (CSs) such as quaternary ammonium compounds are used as fabric softeners, anti-bacterial agents, and human hair cosmetics. Accurate determination of CSs in environmental water samples is very difficult because of their very low concentration and strong adsorptivity to not only glassware but also to plasticware due to strong hydrophobic and electrostatic attractions. Linear alkylbenzene sulfonates (LASs), anionic surfactants, are produced in the largest quantity as the main components of laundry detergents, dishwashing liquids, and other cleaning formulations. In this study, a liquid chromatography/mass spectrometry (LC/MS) method was developed for simultaneous determination of CSs, cetyltrimethylammonium ion (CTMA) and trimethylstearylammonium ion (TMSA), and LASs in environmental water samples. Materials and Methods: This method involves a solid-phase extraction of CSs and LASs from the water samples using a solid-phase extraction cartridge, InertSep Slim-J PLS-3. A hydrophilic polymer column, Shodex MSpak GF-310 4D was used for the separation of CSs and LASs with a mobile phase gradient from 36 to 44 % (v/v) acetonitrile-water containing 0.8 mM di-nbutylammonium acetate and 0.2 M acetic acid. Di-n-butylammonium ion acts as the ion-pair reagent for retention of LASs on the column, while it makes the retention of CSs moderate. Positive and negative electrospray ionization modes were used for the MS detection for CSs and LASs, respectively. Results and Discussion: Instrument detection limits of the developed method based on selected ion monitoring technique for the mixed standard solutions of CSs and LASs were 3 and 6 ng L-1 for CTMA and TMSA, respectively and 13 – 47 ng L-1 for the C10-C14 LASs. The total concentration of the CSs was determined to be 6.6 μg L-1 for river water (Ebi river, Japan) and 0.028 μg L-1 for seawater (Tokyo Bay, Japan) samples. The concentration of total LAS was determined to be 1122 μg L-1 for the river and 10.8 μg L-1 for the seawater samples. Conclusion: These results demonstrate that the solid-phase extraction and the LC/MS method developed in this study are useful for the simultaneous determination of trace amounts of CSs and LASs in environmental water samples.

A Novel Online Hydride Generation Technique for the Simultaneous Determination of Ultra Trace Amounts of Hydride Forming Elements in Water Samples by Inductively Coupled Plasma Optical Emission Spectrometry

A simple and rapid online hydride generation technique based on ultrasonic nebulizer was applied for the first time for the simultaneous determination of trace amounts of As, Bi, Sb, Se and Te by inductively coupled plasma optical emission spectrometry. In this method, we used an ultrasonic nebulizer as a hydride generator and sample introducer simultaneously. An ultrasonic nebulizer was applied for the online hydride generation technique without using any device, such as a gas phase separator, which is mandatory in the classic hydride generation method. This technique improved method detection limit comparing to the traditional hydride generation system which is a necessity in the ultra-trace determination of hydride forming elements. The developed technique shows an improvement factor ranging from 56 to 450 times in detection limits in comparison to a concentric nebulizer. The obtained detection limits were well below the maximum concentration limit. The practical applicability of the developed method was examined using natural water samples.

Rapid Synergistic Cloud Point Extraction (RS-CPE) with Partial Least Squares (PLS) for the Simultaneous Determination of Chlorophenols (CPs) in Environmental Water Samples Using a Microplate Assay (MPA)

A sensitive method termed rapid synergistic cloud point extraction (RS-CPE) combined with partial least squares (PLS) was developed for the extraction and simultaneous determination of trace amounts of phenol and three detrimental chlorophenols (CPs) via a microplate assay (MPA). In this study, n-pentanol was used as a novel synergistic inducer and the linear nonionic surfactant Tergitol 15-S-7 was used as an extractant. The whole process of RS-CPE was accomplished in a few minutes without the need for the time-consuming water- or ice-bath steps used in traditional cloud point extraction. An automated and high-throughput assay using a 96-well plate allowed for the simultaneous processing of multiple samples with low sample volume requirements (approximately 200 µL). However, synchronized determination of several CPs using MPA method was problematic because of spectral interferences. Fortunately, a multivariate calibration method using PLS was applied to circumvent these limitations. Under the optimum conditions, the linear dynamic concentration ranges were from 0.5 to 15 µg/mL for 2-chlorophenol and 0.5 to 20 µg/mL for the other analytes. The detection limit range was from 0.275 to 0.419 µg/mL. The enrichment factor was up to 15.4 fold. The developed methodology was successfully applied to quantitative analysis of phenol and three CPs in water samples with recoveries from 90.0% to 109%.

Development and Validation of an Effective Spectrophotometric Method for Simultaneous Determination of Synthetic Colorants After Cloud Point Extraction and Comparision with New Green HPLC Method.

Background: Synthetic colorants are largely used in the pharmaceutical products to increase the attractiveness of products and to help patients distinguish between pharmaceuticals. Despite their commercial advantages, synthetic colorants may, in some cases, have a negative impact on the human body. It is therefore imperative to measure the quantities in food products and pharmaceuticals with a fast, reliable, and sensitive method. Objective: The analyzed synthetic colorants in this study are Erythrosine [(E) E127], Quinoline Yellow [(QY) E104], and Indigo Carmine [(IC) E132]. The aim of this study was to develop and validate a new method for the preconcentration and simultaneous determination of these colorants in pharmaceutical preparations. Method: The developed method has many advantages such as novelty, sensitivity, cost effectiveness, speed, and environmental friendliness. This method is based on the cloud-point extraction (CPE) method coupled with first-derivative spectrophotometry (FDS). In the proposed method, QY, E, and IC were extracted from an aqueous solution by using mixed micelles of TritonX-100 and cetyltrimethylammonium bromide. The effect of the main parameters such as solution pH, surfactant and salt concentration, incubation time, and temperature on the CPE of colorants were investigated and optimized. Under the optimal conditions, the extracted surfactant-rich phase was diluted with acetone, and the first-derivative absorbance values were measured at wavelengths 408, 497, and 637 nm for QY, E, and IC, respectively. The CPE-FDS method was applied in the range of 1.0-6.0 μg/mL for E and QY, and 0.3-1.8 μg/mL for IC. Results: The results showed higher correlation coefficients of 0.9990-0.9993 for each colorant. Furthermore, the method was validated for precision and accuracy and assessed the colorants' contents in the synthetic mixtures that contained different ratios of colorants and pharmaceutical samples. The LOD and LOQ values were 31.0 and 103.0 ng/mL for E, 57.0 and 190.0 ng/mL for QY, and 48.0 and 160.0 ng/mL for IC, respectively. The RSDs at the intermediate concentration level (1.2 μg/mL for IC and 3 μg/mL for QY and for E) were <5%. The recovery values in different ratios of colorants were in the ranges of 90.42-101.14, 92.40-105.54, and 96.15-101.25% for E, IC, and QY, respectively. CPE-FDS was also successfully applied to the simultaneous analysis of the QY, IC, and E contents in the various pharmaceutical samples. The obtained results were statistically compared with those obtained by the green HPLC method that was previously reported by Yoshioka et al. and modified by us in this study. Conclusions: The data observed indicated that the CPE-FDS method does not require use of great samples for determination of trace amounts of E, IC, and QY and allows for the determination of analytes in high matrix effect samples such as suspension and syrup. The study concludes that the proposed CPE-FDS method could be considered an alternative to the existing chromatographical methods for the simultaneous determination of trace amounts of E, IC, and QY in pharmaceutical dosage forms for routine analysis. Highlights: A new and effective procedure, simultaneous determination, trace amounts of E, QY, and IC was developed. This is the first report that uses CPE coupled with FDS for the analysis of E, QY, and IC. CPE avoids the use of costly, hazardous, and flammable solvents in large quantities. FDS resolves two or three overlapping spectra and eliminates matrix interferences. CPE-FDS did not require use of large samples for determination of trace colorants.

Highly efficient ultrasonic-assisted pre-concentration and simultaneous determination of trace amounts of Pb (II) and Cd (II) ions using modified magnetic natural clinoptilolite zeolite: Response surface methodology

In this work, the synthesis of the magnetic natural clinoptilolite (CP) zeolite modified by cetyltrimethyl ammonium bromide hexadecyl trimethyl ammonium bromide (CTAB) and dithizone was utilized for simultaneous determination of trace amounts of lead (II) and cadmium (II) ions by flame atomic absorption spectrophotometry (FAAS). Characterization of the prepared adsorbent was carried out using various techniques such as XRD, FT-IR, SEM, EDS mapping and BET analyses. Central composite design (CCD) under response surface methodology (RSM) was used for obtaining the most important parameters and probable interactions between variables. In this favor, parameters including adsorbent dosage, pH, adsorption time and desorption time using ultrasound were optimized. Sonication had an important role in shortening the adsorption and desorption times of lead (II) and cadmium (II) ions by enhancing the dispersion of adsorbent in solution. Under optimum conditions, the proposed method represented linear ranges of 2.0–130.0 and 5.0–150.0 μg l−1 for lead and cadmium, respectively; while their corresponding values for limit of detection (LOD) using this method were found to be 0.93 and 1.08 μg l−1. Moreover, these ions exhibited relative standard deviation (RSD %) values of 2.13 and 2.78, respectively. Finally, the application of the synthesized material was evaluated for pre-concentration and determination of Pb (II) and Cd (II) ions from environmental water samples.

Simultaneous determination of trace amounts of copper and cobalt in high concentration zinc solution using UV–vis spectrometry and Adaboost

Simultaneous determination of trace ions in zinc metallurgical solution provides effective process information for optimal control in zinc hydrometallurgy. In this paper, Ultraviolet and Visible (UV–vis) spectrometry with the analytical system based on nitroso R salt is applied to simultaneously determine the trace concentrations of copper and cobalt in high and varying concentration zinc sulfate solution. Firstly, fractional differentiation is applied to reduce the overlap between ions and covering of zinc on trace ions. Then, a multi-indexes fusion wavelength selection is utilized to find the optimal combination of variables for the partial least squares model. Next, to reduce the interference caused by competitive reaction and matrix effect of zinc ions, Adaboost creates a group of weak models to analyze trace ion concentration from multiple perspectives. Finally, Adaboost trains the sample weights and model weights of weak models and integrates those weak models into a strong model to predict the trace ion concentration comprehensively. A spectrum dataset containing 72 samples of zinc, copper and cobalt ions mixture solution is prepared for the proposed method. Results show that the proposed method can simultaneously determine the trace concentrations of copper and cobalt in high and varying concentration zinc sulfate solution accurately.

Simultaneous determination of broflanilide and its metabolites in five typical Chinese soils by a modified quick, easy, cheap, effective, rugged, and safe method with ultra high performance liquid chromatography and tandem mass spectrometry.

An efficient and sensitive analytical method for simultaneous determination of trace amounts of a new insecticide broflanilide and its metabolites (S(PFH-OH)-8007 and DM-8007) residues in five typical Chinese soils (red soil, black soil, fluvo-aquic soil, cinnamon soil and paddy soil) was developed. The samples were prepared by a modified quick, easy, cheap, effective, rugged, and safe method. The determination of broflanilide and its metabolites was conducted by ultra high performance liquid chromatography with tandem mass spectrometry with an electrospray ionization source in the positive ion mode. This is the first report for the determination of broflanilide and its metabolites in different soils. Broflanilide and its metabolites were extracted from all soils with acetonitrile and purified by a mixture of primary secondary amine and graphitized carbon black. The average recoveries of the three compounds in five types of soil ranged from 85.3 to 111.8% and the relative standard deviations were less than 13.6%. The limit of quantification was 0.1 μg/kg for all three compounds. This method was successfully used to determine broflanilide and its metabolites in five types of soil. The method was validated to be simple and effective for the determination of trace residual broflanilide and its metabolites in five types of soil.

Simultaneous determination of lead(II) and cadmium(II) at a glassy carbon electrode modified with GO@Fe3O4@benzothiazole-2-carboxaldehyde using square wave anodic stripping voltammetry

Magnetic graphene oxide (GO@Fe3O4) modified with benzothiazole-2-carboxaldehyde (2-CBT) was used for the first time for the simultaneous determination of trace amounts of lead and cadmium in the aqueous solution by means of square wave anodic stripping voltammetry (SWASV). The novel nanocomposite (GO@Fe3O4@2-CBT) was evaluated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and thermogravimetric analysis (TGA). The effects of several factors such as pH, deposition potential, deposition time, type of the supporting electrolyte, and potentially interfering ions were investigated. Under the optimum conditions, the limits of detection (LODs) calculated using 3(Sb) blank/m and were 0.03ngmL−1 and 0.02ngmL−1 for Cd(II) and Pb(II) respectively. As a selective and sensitive sensor, the modified electrode was applied in order to determine Pb(II) and Cd(II) ions in different water samples with very satisfactory results.

Simultaneous determination of rhodium and ruthenium by high-resolution continuum source graphite furnace atomic absorption spectrometry

In the present paper a fast, simple and sensitive analytical method for simultaneous determination of rhodium and ruthenium by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) was developed. Among six pairs of absorption atomic lines of Rh and Ru, which are close enough to enable their simultaneous detection, two pairs were selected for further studies. Best results were obtained for measurements of the resonance line of rhodium at 343.489nm and the adjacent secondary line of ruthenium at 343.674nm (23% intensity of this line). For evaluated lines, the absorbance values were obtained using three pixels. The pyrolysis and atomization temperatures were 1200°C and 2600°C, respectively. Under these conditions the limits of detection achieved for Rh and Ru were found to be 1.0μgL−1 and 1.9μgL−1, respectively. The characteristic mass was 12.9pg for Rh and 71.7pg for Ru. Repeatability of the results expressed as a relative standard deviation was typically below 6%.The trueness of the method was confirmed by analysis of the certified reference material – platinum ore (SARM 76). The recovery of Rh and Ru from the platinum ore was 93.0±4.6% and 90.1±2.5%, respectively. The method was successfully applied to the direct simultaneous determination of trace amounts of rhodium and ruthenium in spiked river water, road runoff, and municipal sewage. Separation of interfering matrix on cation exchange resin was required before analysis of road dust and tunnel dust (CW-7) by HR-CS GFAAS.

A new method for simultaneous determination of trace amounts of Cu(II) and Ni(II) ions by preconcentration and spectrophotometric analysis

Immediate preconcentration and spectrophotometric methods have been developed for the determination of trace amounts of cupric ion (Cu(II)) and nickel ion (Ni(II)) through a solid phase extraction with XAD-4-N,N'-bis-(salicylidene) cyclohexanediamine (XAD-4-SCHD) resin and a complex color reaction of the ions with 2,6-dimethyl-morpholine dithiocarbamate (DMMDTC) in Triton X-100 media. A high preconcentration factor of 125 was achieved. The spectrophotometric method was based on the measurements of the absorption of colored chelates of ions complexing with DMMDTC, and the adsorptions of the complex solutions were measured at their maximum absorption peaks at 460 and 328 nm for Cu(II) and Ni(II) ions, respectively. The impact of the complexing reaction variables including type and amount of surfactant, pH, amount of ligand, and complexation time on the sensitivity of the proposed method was optimized. Calibration graphs were found to be linear in the ranges of 0.02-3 and 0.02-2.5 mg L$^{-1}$ with detection limits of 5 and 7 $\mu $g L$^{-1}$ for Cu(II) and Ni(II), respectively. The accuracy of the developed method was calculated by recovering all Cu(II) and Ni(II) ions in synthetic and TMDA-70.2 certified reference water samples. Results of the proposed method were also compared with inductively coupled plasma-mass spectrometry results for the determination of trace Cu(II) and Ni(II) ions in water samples.

Nanostructured Sensor for Simultaneous Determination of Trace Amounts of Bisphenol A and Vitamin B6 in Food Samples

Rapid analysis of health hazardous materials is necessary to prevent foodborne illness in food control science. Bisphenol A (BPA) is one of the potentially hazardous materials that may potentially create adverse health effects, if its concentration level in food is not controlled. In this work, carbon paste electrode has been modified with CdO nanoparticles and ionic liquid (IL/CdO/CPE) for determination of BPA in food samples. In addition, vitamin B6 (B6) has separated oxidation peak at modified electrode and simultaneous determination of BPA and B6 is possible. The square wave voltammetric peak currents of BPA and B6 at IL/CdO/CPE have linear relation to their concentrations in the range of 0.01 to 800 μmol L−1 BPA and 0.4 to 500 μmol L−1 B6. Selectivity of the modified electrode was studied, and it was successfully applied for analysis of food samples.

Reagent optimization for on-line simultaneous polarographic determination of trace amounts of Cu2+, Cd2+ and Co2+ in the presence of anextremely large excess of Zn2+

Reagents are optimized for the simultaneous determination of trace amounts of Cu2+, Cd2+ and Co2+ in zinc sulfate solution, which contains an extremely large excess of Zn2+. First, the reagents and their doses for the experiment are selected according to the characteristics of the zinc sulfate solution. Then, the reagent doses are optimized by analyzing the influence of reagent dose on the polarographic parameters (i.e. half-wave potential E1/2 and limiting diffusion current Ip). Finally, the optimization results are verified by simultaneously determining trace amounts of Cu2+, Cd2+ and Co2+ in the presence of an extremely large excess of Zn2+. The determination results indicate that the optimized reagents exhibit wide linearity, low detection limits, high accuracy and good precision for the simultaneous determination of trace amounts of Cu2+, Cd2+ and Co2+ in the presence of an extremely large excess of Zn2+.

Simultaneous determination of estrogenic odorant alkylphenols, chlorophenols, and their derivatives in water using online headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

A simple online headspace solid-phase microextraction (HS-SPME) coupled with the gas chromatography-mass spectrometry (GC-MS) method was developed for simultaneous determination of trace amounts of nine estrogenic odorant alkylphenols and chlorophenols and their derivatives in water samples. The extraction conditions of HS-SPME were optimized including fiber selection, extraction temperature, extraction time, and salt concentration. Results showed that divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was the most appropriate one among the three selected commercial fibers, and the optimal extraction temperature, time, and salt concentration were 70°C, 30min, and 0.25g/mL, respectively. The developed method was validated and showed good linearity (R (2) > 0.989), low limit of detection (LOD, 0.002-0.5μg/L), and excellent recoveries (76-126%) with low relative standard deviation (RSD, 0.7-12.9%). The developed method was finally applied to two surface water samples and some of these target compounds were detected. All these detected compounds were below their odor thresholds, except for 2,4,6-TCAS and 2,4,6-TBAS wherein their concentrations were near their odor thresholds. However, in the two surface water samples, these detected compounds contributed to a certain amount of estrogenicity, which seemed to suggest that more attention should be paid to the issue of estrogenicity rather than to the odor problem.

Simultaneous determination of trace amounts of anti-hypertensive drugs in urine using magnetic mixed hemimicelles solid-phase extraction combined with HPLC-UV

Hypertension is the leading cause of morbidity and mortality in developed and developing countries. The combination of amlodipine and carvedilol is very effective for reducing blood pressure and improving treatment compliance. Determination of drugs in biological fluids is vital in therapeutic efficacy. In the present study, a simple, rapid and efficient magnetic solid phase extraction procedure based on mixed hemimicelles is described and validated for the simultaneous determination of trace amounts of anti-hypertensive drugs in urine samples using sodium dodecyl sulfate-coated magnetite nanoparticles as extractant. Various factors, which could affect the extraction efficiency were investigated and optimized. Under the optimum conditions, the limits of detection (S/N = 3) for amlodipine and carvedilol were 5 and 2 ng/mL, respectively. The relative standard deviation for six measurements of 50 ng/mL of amlodipine and carvedilol were 4.7 and 5.2%, respectively. The developed method was applied to the analysis of patients' urine samples, and satisfactory results were obtained in the range between 81.6 and 92.7%.

Solid-Phase Extraction Combined with Dispersive Liquid–Liquid Microextraction for the Simultaneous Determination of Deltamethrin and Permethrin in Honey by Gas Chromatography–Mass Spectrometry

In this study, solid-phase extraction combined with dispersive liquid–liquid microextraction is presented for the simultaneous determination of trace amounts of deltamethrin and permethrin in honey by gas chromatography–mass spectrometry. First, permethrin and deltamethrin were extracted from polluted honey samples by ultrasound-assisted liquid–liquid extraction followed by solid-phase extraction (SPE). Then, the analytes were eluted from the SPE cartridge. The elution solvent containing trace amounts of analytes was applied in dispersive liquid–liquid microextraction (DLLME) step as disperser solvent for further purification and preconcentration of deltamethrin and permethrin. The important parameters such as the type and volume of the solvent for initial extraction of pesticides from honey matrix, the amount of honey, and type and volume of extraction solvent and elution solvent (disperser solvent) were investigated through the process. Under the optimal conditions, good linearity in the range of 0.2–800 ng g−1 with the correlation coefficient (r 2) >0.9986 and 0.9990, low limits of detection (LODs) of 0.02 and 0.04 ng g−1, enrichment factors of 4955 and 4925, and relative standard deviations (RSD%, n = 7) of 1.8 and 2 % were obtained for permethrin and deltamethrin, respectively. The proposed procedure showed satisfactory results for simultaneous determination of deltamethrin and permethrin in honey. Relative recoveries of 94–99.2 % were obtained for real sample analysis.

Analytical capabilities of two-phase hollow-fiber liquid phase microextraction for trace multielement determination in aqueous samples by means of portable total reflection X-ray instrumentation

Liquid phase microextraction (LPME) procedures have been widely used in combination with atomic and emission spectroscopic techniques for the isolation and preconcentration of trace elements. However, its application in combination with total reflection X-ray spectrometry (TXRF) is still scarce. In this paper, we evaluate the possibilities and drawbacks of a two-phase hollow fiber LPME procedure in combination with TXRF for the simultaneous determination of trace amounts of Cr, Ni, Cu, Zn, Pb, and Cd in aqueous samples. After extraction of the analytes by using the optimum conditions (sample volume: 25 mL, complexing agent: APDC, organic solvent: hexylbenzene, extraction time: 2 h, extraction speed: 660 rpm), 10 $\mu $L of the preconcentrated sample was deposited on a preheated quartz reflector, dried on a hot plate at 80 $^{\circ}$C, and analyzed by TXRF. Using such conditions, limits of detection lower than 3 $\mu $g L$^{-1}$ were obtained for all metals. In spite of LODs improvement in comparison with the direct analysis of the aqueous samples (up to a factor of 100), precision of the results was not optimal (RSD$\sim $20%). This fact may be related to the use of a low volatility solvent as extractant phase that hampers the later TXRF analysis.