Eluent Volume Research Articles

Determination of ten iodinated X-ray contrast media by solid-phase extraction and ultra-high performance liquid chromatography coupled with high-resolution orbitrap mass spectrometry

A highly sensitive method for the simultaneous determination of ten iodinated X-ray contrast media (ICM) in environmental water samples was developed, in which samples were pretreated using solid-phase extraction and analyzed by ultra-high performance liquid chromatography coupled with high-resolution orbitrap mass spectrometry. A combination of two ENVI-Chrom P cartridges was selected due to its high recoveries of ICM. The optimized sample pH, flow rate, eluent type, and volume of eluent were 2.0, 6 mL/min, MeOH/ACN (50:50, v/v), and 6 mL, respectively. The developed method was used for the tap, surface, and waste water sample analysis, and exhibited satisfactory accuracy (80.8-118.5%), high precision (0.1-11.6%), and low detection limits (0.3-1.0 ng/L). These results indicate that this method is highly effective for the simultaneous determination of trace-level ICM in the aquatic environment.

Magnetic Solid-Phase Extraction Based on Magnetite-Multiwalled Carbon Nanotubes of Non-Steroidal Anti-Inflammatories from Water Followed by LC-ESI-MS/MS.

An analytical method based on liquid chromatography-electrospray ionization-tandem mass spectrometry detection (LC-ESI-MS/MS) has been developed for the determination of pharmaceutical compounds in water samples. Five non-steroidal anti-inflammatory drugs (NSAIDs) namely Naproxen, Ketoprofen, Piroxicam, Diflunisal and Celecoxib were investigated. Magnetic solid phase extraction (MSPE) was used for sample pre concentration of water samples and magnetic carbon nanotubes (Fe3O4-MWCNTs) were considered as solid phase extraction sorbent. Important parameters influencing the extraction efficiency such as nature and volume of eluent, sample pH and adsorbent mass were optimized. The developed MSPE method involved 75mg of Fe3O4-MWCNTs sorbent, 5mL of water sample at pH = 4 and 5mL of 10% ammonia in methanol in the elution step. Under the optimized extraction conditions, linearity, detection and quantification limits and reproducibility were evaluated. The proposed method was successfully applied to the analysis of NSAIDs in surface waters, and mean recoveries of all the NSAIDs were above 90% with relative standard deviations < 17%. The detection and quantification limits were comprised between 0.05-3.6ng.mL-1 and 0.2-11.9ng.mL-1, respectively.

Magnetic solid‐phase extraction and spectrophotometric determination of pseudoephedrine in real samples

AbstractIn the present study, the magnetic iron oxide nanoparticles as an efficient sorbent were successfully utilized for the investigation of pseudoephedrine in water and urine samples before spectrophotometric evaluation. Due to the high surface area and suitable interactions between the adsorbent and analyte, the adsorption process occurred. The optimization process was applied to the parameters that might have an impact on the extraction efficiencies, including the pH, sorbent quantity, salt effect, type and volume of eluent, and the contact time affecting the adsorption and desorption of the analyte. By exerting the optimum procedure, the proper linearities ranging from 1 to 30 and 1 to 24 μg/mL with good correlation coefficients of 0.999 and 0.998 enhanced for water and urine samples. This method is proved to be as accurate and precise as it is necessary to be executed for the analytical measurements, since the measured recoveries were 99 and 96.12%, with the detection limits of 0.88 and 1.003 μg/mL for water and urine samples, respectively. The obtained results indicate that the proposed method is simple, effective, and inexpensive for the measurements of pseudoephedrine in water and urine samples.

Preparation of an Immunoaffinity Column Based on Bispecific Monoclonal Antibody for Aflatoxin B1 and Ochratoxin A Detection Combined with ic-ELISA.

A novel and efficient immunoaffinity column (IAC) based on bispecific monoclonal antibody (BsMAb) recognizing aflatoxin B1 (AFB1) and ochratoxin A (OTA) was prepared and applied in simultaneous extraction of AFB1 and OTA from food samples and detection of AFB1/OTA combined with ic-ELISA (indirect competitive ELISA). Two deficient cell lines, hypoxanthine guanine phosphoribosyl-transferase (HGPRT) deficient anti-AFB1 hybridoma cell line and thymidine kinase (TK) deficient anti-OTA hybridoma cell line, were fused to generate a hybrid-hybridoma producing BsMAb against AFB1 and OTA. The subtype of the BsMAb was IgG1 via mouse antibody isotyping kit test. The purity and molecular weight of BsMAb were confirmed by SDS-PAGE method. The cross-reaction rate with AFB2 was 37%, with AFG1 15%, with AFM1 48%, with AFM2 10%, and with OTB 36%. Negligible cross-reaction was observed with other tested compounds. The affinity constant (Ka) was determined by ELISA. The Ka (AFB1) and Ka (OTA) was 2.43 × 108 L/mol and 1.57 × 108 L/mol, respectively. Then the anti-AFB1/OTA BsMAb was coupled with CNBr-Sepharose, and an AFB1/OTA IAC was prepared. The coupling time and elution conditions of IAC were optimized. The coupling time was 1 h with 90% coupling rate, the eluent was methanol–water (60:40, v:v, pH 2.3) containing 1 mol/L NaCl, and the eluent volume was 4 mL. The column capacities of AFB1 and OTA were 165.0 ng and 171.3 ng, respectively. After seven times of repeated use, the preservation rates of column capacity for AFB1 and OTA were 69.3% and 68.0%, respectively. The ic-ELISA for AFB1 and OTA were applied combined with IAC. The IC50 (50% inhibiting concentration) of AFB1 was 0.027 ng/mL, the limit of detection (LOD) was 0.004 ng/mL (0.032 µg/kg), and the linear range was 0.006 ng/mL~0.119 ng/mL. The IC50 of OTA was 0.878 ng/mL, the LOD was 0.126 ng/mL (1.008 µg/kg), and the linear range was 0.259 ng/mL~6.178 ng/mL. Under optimum conditions, corn and wheat samples were pretreated with AFB1-OTA IAC. The recovery rates of AFB1 and OTA were 95.4%~105.0% with ic-ELISA, and the correlations between the detection results and LC-MS were above 0.9. The developed IAC combined with ic-ELISA is reliable and could be applied to the detection of AFB1 and OTA in grains.

Development of dispersive solid-phase microextraction coupled with high-pressure liquid chromatography for the preconcentration and determination of the selected neonicotinoid insecticides

Neonicotinoid insecticides have raised a lot of societal concerns due to their environmental ubiquity and unique mode of action. Therefore, it is of great research interest to monitor their occurrence in the environmental waters. However, these compounds exist at low concentrations that is below instrument detection limits. This study reports the applicability of magnetic poly (3 aminobenzoic acid)-based activated carbon (Fe3O4@PABA/AC) composite as an adsorbent in dispersive magnetic solid-phase microextraction (d-MSPME) of neonicotinoid insecticides from wastewater and river water samples. The as-synthesized adsorbent was characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller and X-ray diffraction spectroscopy. The analytes of interest were detected and quantified by high-performance liquid chromatography coupled with diode array detector (HPLC–DAD). The parameters affecting the extraction and preconcentration processes, such as pH, extraction time, mass of adsorbent, desorption time and eluent volume, were optimized using fractional factorial design and central composite design. Under optimum conditions, the limits of detection and quantification were in the ranges of 0.41–0.82 µg L−1 and 1.4–2.7 µg L−1, respectively. The linearity ranged from 1.4–700 µg L−1 with correlation of determination (R2) values varied between 0.9933 and 0.9987. The intra-day and inter-day precisions were 0.35–0.75% and 1.7–5.5%, respectively. The spike recovery experiments were conducted to evaluate the accuracy of the d-MSPME analytical method in real samples, and the percentage recoveries ranged from 86.7 to 99.2%. Therefore, this method shows great potential applicability in preconcentrating the pollutants from the environment.

Optimization and modeling of solid-phase extraction of rare earth elements with chert using design methodology

The cherty rocks, the most abundant byproduct of the mining industry, were applied as an adsorbent in the solid-phase extraction of six rare earth elements from aqueous solutions. Purified chert was characterized by various analytical methods. The adsorption and desorption steps were evaluated separately using experimental design methodology. Four variables (sorbent amount and sample volume, pH, and flow rate) were regarded as factors in the optimization of the adsorption step using an FFD 24−1 Design. While eluent volume, concentration, and flow rate were modeled and optimized by Box-Behnken design (BBD) combined with response surface methodology. The eluent volume followed by the eluent concentration was statistically significant parameters on the desorption step. The best results were obtained when an aqueous solution of REE (500 mL) was adjusted to pH 6 and passed, at 8 mL min−1 loading flow rate, through the cartridge containing 500 mg of chert. SPE method was evaluated statistically and showed good repeatability and reproducibility. The detection and quantification limits were found between 0.025 and 0.075 mg L−1 and 0.084 and 0.250 mg L−1, respectively. Extraction recovery percentages of all the REE were 80.13, 95.25, 97.30, 88.10, 82.80, and 91.99% for Eu(III), Yb(III), La(III), Gd(III), Ce(III), and Nd(III), respectively.

Self-assembly of core–shell structured multiwalled nanotubes@covalent organic frameworks composite for solid-phase extraction of four phytohormones from fruit juices

Covalent organic frameworks (COFs) have attracted considerable attention in sample pretreatment because of their unique characteristics. However, the submicron or micron size of COFs has restricted their wider applications in solid-phase extraction (SPE). Herein, multiwalled nanotubes (MWNTs) were used as substrate materials to synthesize core–shell structured MWNTs@COFs composites (MWNTs@SNW-1) using a simple self-assembly method. The as-prepared MWNTs@SNW-1 composite exhibited a high BET surface area, good thermal stability, and good adsorption capacity. The MWNTs@SNW-1 composite was used as an adsorbent in cartridge-based SPE to extract four phytohormones before determining their levels by high-performance liquid chromatography. The experimental parameters affecting extraction efficiency, including the amount of adsorbents, solution pH, ionic strength, eluent type, and eluent volume, were investigated. The developed method showed a wide linear range (0.37–100 ng mL−1), low detection limits (0.11–0.32 ng mL−1), low limits of quantification (0.37–1.07 ng mL−1), high enrichment factors (45.9–49.3), and good reproducibility (<4.8%) for phytohormones. The developed analytical method was used to analyze trace phytohormones in fruit juices with good recoveries, highlighting the potential of the MWNTs@SNW-1 composite as an adsorbent in sample preparation.

Ionic liquid-immobilized silica gel as a new sorbent for solid-phase extraction of heavy metal ions in water samples.

In the current study, we have developed a solid-phase extraction (SPE) method with novel C18-alkylimidazolium ionic liquid immobilized silica (SiO2–(CH2)3–Im–C18) for the preconcentration of trace heavy metals from aqueous samples as a prior step to their determination by inductively coupled plasma mass spectrometry (ICPMS). The material was characterized by Fourier-transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Energy-Dispersive X-ray Spectroscopy (EDS), and Brunauer–Emmett–Teller (BET) analysis. A mini-column packed with SiO2–(CH2)3–Im–C18 sorbent was used for the extraction of the metal ions complexed with 1-(2-pyridylazo)-2-naphthol (PAN) from the water sample. The effects of pH, PAN concentration, length of the alkyl chain of the ionic liquid, eluent concentration, eluent volume, and breakthrough volume have been investigated. The SiO2–(CH2)3–Im–C18 allows the isolation and preconcentration of the heavy metal ions with enrichment factors of 150, 60, 80, 80, and 150 for Cr3+, Ni2+, Cu2+, Cd2+, and Pb2+, respectively. The limits of detection (LODs) for Cr3+, Ni2+, Cu2+, Cd2+, and Pb2+ were 0.724, 11.329, 4.571, 0.112, and 0.819 μg L−1, respectively with the relative standard deviation (RSD) in the range of 0.941–1.351%.

Determination of organophosphorus pesticides based on graphene oxide aerogel solid phase extraction column

以氧化石墨烯气凝胶三维纳米材料作为固相萃取的吸附剂,结合高效液相色谱,对食品中的有机磷农药(辛硫磷、双硫磷、倍硫磷、杀螟硫磷)进行检测分析。首先,利用冷冻干燥的方式制备得到氧化石墨烯气凝胶,通过扫描电镜、红外光谱、比表面积吸附等一系列的实验手段对其形貌及物理特性进行了表征,证明其成功合成。从扫描电镜中可见石墨烯的层状褶皱结构,其表面积为740.51 m2/g。然后,将氧化石墨烯气凝胶直接填充于固相萃取柱中,在未借助任何硅胶等基体的条件下进行萃取研究;通过单因素实验,系统研究了萃取和洗脱条件对有机磷农药萃取回收率的影响。结果显示,在上样体积15 mL、样品溶液pH值4、上样速率1.0 mL/min、洗脱剂1.0 mL乙腈的条件下萃取回收率最高。与商用的萃取材料进行比较,包括碳十八硅胶柱(C18)、阴离子交换柱(SAX)、氨基柱(-NH2)和硅酸镁柱(Florisil),氧化石墨烯气凝胶填充的固相萃取柱的萃取回收率有明显提高。实验考察了氧化石墨烯气凝胶直接填充的萃取柱的寿命,结果显示该萃取柱可以重复使用15次,可见解决了分散无基体支撑的石墨烯纳米片容易破碎、堵塞筛板的问题。与液相色谱联用建立分析方法,4种有机磷农药的线性范围较宽,辛硫磷、双硫磷和倍硫磷的线性范围为1~200 μg/L,杀螟硫磷的线性范围为2~200 μg/L,线性拟合良好(线性相关系数r2≥0.9949),检出限为0.2~0.5 μg/L,满足于我国和其他国家限定标准的检测。将该方法应用于实际样品,在苹果皮中未检测到有机磷农药,对其进行加标,回收率为70.5%~93.6%,相对标准偏差≤10.4%。

MIL-101(Cr) based d-SPE/UPLC-MS/MS for determination of neonicotinoid insecticides in beverages

Metal organic framework MIL-101(Cr) was successfully synthesized as a selective adsorbent by a facile self-assembly technique and combined with UPLC-MS/MS for enrichment and determination of neonicotinoids in fruit juices and tea beverages. Therein, MIL-101(Cr) was characterized by Fourier transform infrared spectrometry, scanning electron microscopy, X-ray diffraction, and N2 adsorption–desorption isotherms. Box-Behnken design was applied to optimize the significant variables including the sorbent amount, pH of the matrix, eluant volume, extraction time and desorption time. The optimized conditions were sorbent amount of 20 mg, eluent volume of 1 mL, extraction time of 5 min and desorption time of 4 min. Under the optimized conditions, excellent sensitivity was achieved with the limit of detection of 0.0019–0.02 μg/L and limit of quantification of 0.0063–0.067 μg/L. Good linearity (R2 ≥ 0.9988) was obtained within the range of 1–1000 μg/L, and the recovery was 71.04%-101.64% with relative standard deviations (RSDs) of 1.25%-8.82% in spiked samples. The inter- and intra-day RSDs were both<8.54%. The adsorption isotherms investigated for acetamiprid, thiacloprid, and imidacloprid pesticides better fitted with the Freundich adsorption isotherm with bimolecular adsorption capacity of 71.43, 68.49, and 50.38 mg/g, respectively. These results indicate that the nanocomposite is feasible for adsorption of the target analytes at trace amounts from fruit juices and tea beverages.

Trace Determination of Rhodium in Coating Wastewater by Vortex Assisted Magnetic Nanoparticle Based Solid Phase Microextraction (MNP-SPME) Combined with Slotted Quartz Tube–Flame Atomic Absorption Spectrometry (SQT-FAAS) with Matrix Matching Calibration

A magnetic nanoparticle based solid phase microextraction method (MNP-SPME) was developed for the extraction/preconcentration of rhodium prior to determination by slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS). The extraction efficiency was enhanced by the binary MNPs (uncoated MNPs and amidosulfonic acid coated MNPs). The parameters affecting rhodium extraction such as the pH and volume of buffer solution, mixing type/period after the addition MNPs and sample volume were optimized by univariate optimization. Box-Behnken design with five center points was also used as a multivariate approach for the determination of the optimum values of the MNP mass and percentages and eluent volume. Under the optimum conditions, the limits of detection and quantitation were 0.3 and 1.1 µg L−1. In order to characterize the applicability/accuracy of the method, spiking experiments were performed in metal coating wastewater. Recoveries were between 95.5% and 102.9% using matrix matching calibration. The developed method achieved a 129.1-fold enhancement in detection power compared to FAAS. The recovery results demonstrated the accuracy of the developed strategy for the determination of rhodium in complex matrices.

Separation-preconcentration and ultra trace lead determination in the environmental sample by a combination of ion-imprinted polymer and solidification of floating organic drop microextraction

ABSTRACT The ion-imprinted polymer combined with the solidification of floating organic drop microextraction has been developed as an ultra-pre-concentration technique to determine lead ions in real samples. In ion-imprinted polymer – solidification of floating organic drop microextraction, lead was adsorbed from a large volume of aqueous samples (500 mL) into 100 mg of the ion-imprinted polymer sorbent. After the elution of lead ions from the sorbent by using nitric acid, the solidification of floating organic drop microextraction technique was performed on the obtained solution. Several important extraction parameters, such as weight of ion-imprinted polymer (mg), pH, uptake time (min), desorption time (min), HNO3 desorption volume (mL) aqueous-phase volume (mL), were studied and optimised. The ion–imprinted polymer particles were characterised by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The new method (SPE–SFODME) provided an ultra-enrichment factor (5000) for lead. The calibration graphs were linear in the range of 5–200 ng L−1. The optimum conditions for the method were as follows: pH of solution, 7.5; weight of ion-imprinted polymer, 100 mg; type and concentration of eluent, HNO3 1 M; volume of eluent, 1 mL; sorption time, 25 min; desorption time, 15 min. Under optimum conditions, the limit of detection (LOD) was 1 ng L−1 for lead and relative standard deviation (RSD %) for five replicate determinations of 10 ng L−1 for lead was 6.5%. The results for the determination of lead ions in reference materials, tap water, ground vegetables, butter and flour wheat demonstrated the accuracy, recovery and applicability of the presented method.

Cadmium selenide and carbon nanodots modified magnetite nanospheres for the magnetic solid-phase extraction (MSPE) of malachite green prior to spectrophotometric determination

CdSe-carbon nanodots modified magnetic Fe3O4 nanospheres (CdSe-NDs@C-NDs@Fe3O4) were synthesized by a simple hydrothermal technique and characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) with mapping, and energy dispersive X-ray spectroscopy (EDX). The prepared material was used as a magnetic solid phase microextraction (MSPE) adsorbent to determine malachite green (MG). Pasteurized cow’s milk was used as the carbon source to fabricate the carbon nanodots. The spectrophotometric determination of malachite green was performed at 625 nm. The parameters affecting the microextraction efficiency were optimized, including the pH (9.0), mass of adsorbent (5 mg), eluent type (0.1 M acetic acid in ethanol), eluent volume (0.75 mL), sample volume (10 mL), in addition to matrix studies. In order to evaluate the accuracy of the method, real samples were subjected to addition-recovery tests and the recovery values from 85% to 104% were obtained. The limits of detection (LOD) and quantitation (LOQ) of the developed method were 0.013 µg mL−1 and 0.042 µg mL−1, respectively.

Determination of Silver in Metal Plating Wastewater by Slotted Quartz Tube Flame Atomic Absorption Spectrometry (SQT-FAAS) after Preconcentration with Stearic Acid-Coated Magnetite Nanoparticle-Based Solid-Phase Microextraction (SA-MNP-SPME)

Here is reported the determination of silver at ultratrace levels by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS) following stearic acid coated magnetic nanoparticle based solid phase microextraction (SA-MNP-SPME). The parameters affecting silver extraction were optimized to obtain high efficiency. In addition to the magnetic property of iron oxide (Fe3O4) nanoparticles, they were coated with stearic acid to increase the surface area and the capacity for the analyte. An external magnetic field was used to separate the silver from the liquid phase. To obtain the highest efficiency, the mass of magnetic nanoparticles, pH and volume of buffer solution, mixing type and period, volume of eluent and volume of sample were optimized univariately. Under the optimum conditions, the limits of detection and quantitation were determined to be 40 and 130 ng L−1, respectively. Recovery experiments were performed to investigate matrix effects on the developed method by spiking real samples. Recoveries were between 96.3 and 105.1% with low standard deviations by the matrix matching calibration. The developed MNP-SPME-SQT-FAAS method achieved 305-fold improvement in detection power. These results demonstrated the method’s applicability for the determination of trace silver in complex samples with good accuracy and precision.

Highly effective pre-concentration of thymol and carvacrol using nano-sized magnetic molecularly imprinted polymer based on experimental design optimization and their trace determination in summer savoury, Origanum majorana and Origanum vulgare extracts

To ascertain thymol and carvacrol in pharmaceutical syrups, a valid and effective magnetic molecular imprinted polymer dispersive solid phase microextraction (MMIP-DSPME) process was developed in this study, which was in combination with a high performance liquid chromatography-ultra violet (HPLC-UV) technique for the assessment of thymol and carvacrol separation and pre-concentration. Contact time, eluent kind and volume, pH, the mass of the MMIP were all taken into consideration as key factors. Design expert and multi-objective response surface methodology (RSM) were used to optimize these variables. The mass of the MMIP, sample pH, eluent kind, time of sorption, the volume of eluent, and time of elution were 10 mg, 6, acetonitrile, 28 min, 200 µL, and 5.5 min, respectively, for the maximum extraction recovery of the analytes. The limit of detection (LOD) was 0.042 ng mL−1 at the optimal conditions, while the value for the limit of quantification (LOQ) was 0.140 ng mL−1. At the optimized conditions for thymol and carvacrol, the suggested MMIP sorbent had sorption capacities of 64.1 and 72.6 mg g−1, respectively. Furthermore, for triplicate measurements, the linear dynamic range (LDR) was 0.40–5000 ng mL−1, and the method's accuracy (RSD %) was 6.26%. The saturation magnetization for the MMIP was 19.0 emu g−1 obtained by VSM, allowing the sorbent to be separated quickly. The sorption experiments confirmed the large sorption capacity of the MMIP for thymol and carvacrol, as well as its homogeneous binding sites. The extraction recovery for thymol and carvacrol was 96.9–103.8% and 96.6–105.4%, respectively, at all spiked amounts (20, 100, 200, and 500 ng mL−1). The findings of seven desorption–regeneration cycles using MMIP demonstrated the high stability of the sorbent. The MMIP revealed a particular behavior of sorption for thymol and carvacrol, implying a selective, simple, effective, and flexible analytical method.

STANDARDIZATION PROBLEMS OF MEDICINAL PREPARATIONS FROM RHODIOLA ROSEA L.

Rhodiola rosea L. rhizomes and roots are pharmacopoeial raw materials, which are used in official medicine for obtaining medicines with adaptogenic activity. One of the most common problems in the production of medicines from Rhodiola rosea L. rhizomes and roots is the use of poor quality medicinal plant materials, which leads to the absence of biologically significant compounds in the preparations. One of the possible reasons is the shortcomings in the existing approaches to the standardization of Rhodiola rosea L. raw materials and preparations.The aim of the study is the improvement of approaches to the standardization of medicinal preparations from Rhodiola rosea L. rhizomes and roots.Materials and methods. Experimental and industrial samples of liquid extract from Rhodiola rosea L. roots, as well as reference samples of rosavin and salidroside, were used as materials of the research. The HPLC analysis was carried out using a Milichrom-6 chromatograph (NPAO Nauchpribor) under the following conditions of reversed-phase chromatography in an isocratic mode: a steel column KAKH-6-80-4 (2 mm x 80 mm; Separon-C18 7 μm), a mobile phase – acetonitrile: 1% solution of acetic acid in water in the ratio of 14:86, the elution rate was 100 μL/min, the eluent volume was 2000 μL. The constituents were detected at the wavelength of 252 nm (rosavin) and 278 nm (salidroside).Results. An assay of rosavin and salidroside in the liquid extract of Rhodiola rosea L. was developed using the HPLC method. It was determined that the content of rosavin in the samples of the liquid extracts obtained from Rhodiola rosea L. rhizomes and roots of the pharmacopoeial quality, varied from 0.21%±0.03% to 0.32%±0.04%, salidroside – from 1.13% ±0.05% to 2.71%±0.12%, respectively. The results of statistical processing indicate that the relative error of the average result for the determination of rosavin and salidroside in the preparations of Rhodiola rosea L. with a confidence level of 95% does not exceed ±6.0%.Conclusion. Thus, methodological approaches to the analysis of medicinal preparations from Rhodiola rosea L. rhizomes and roots have been substantiated. These methodological approaches consist of the quantitative determination of the dominant and diagnostically significant biologically active compounds – rosavin and salidroside.

Simultaneous Determination of Polychlorinated Biphenyl 101 (PCB101) and Its Hydroxylated, Methoxylated and Methyl Sulfonated Metabolites in Aquatic Organisms by Solid-Phase Extraction (SPE) and Gas Chromatography–Microelectron Capture Detection (GC-μECD)

Polychlorinated biphenyls (PCBs), a group of persistent organic pollutants, are ubiquitous in the environment. The concentrations of PCBs and their metabolites are crucial to understand their impact on the environment. Here, a simultaneous method is reported to determine PCB101 and its hydroxylated, methoxylated and methyl sulfonated metabolites in aquatic organisms by gas chromatography–microelectron capture detection (GC-μECD). Several operational parameters, including the extraction solvent, volume of concentrated sulfuric acid for lipid removal, elution procedure, and solid-phase extraction (SPE) eluent volume, were optimized for the analytes in the muscle tissue of carp (Carassius auratus). Under the optimum conditions, the linearity of the method was from 2.5 to 100 ng/mL with correlation coefficients (R 2) > 0.9961. The limit of detection was 2.00 μg/kg, and the limit of quantitation was equal to 5.00 μg/kg. The spiked recoveries of the targets in carp muscles were from 84.4% to 104%, and the relative standard deviation (RSD) was from 4.02% to 8.75%. The developed method was successfully applied to different aquatic samples. The precursor and metabolites were simultaneously detected in aquatic products. The metabolites of PCBs were present in marine samples collected from the East China Sea. For the first time, the methoxylated metabolite of PCB101 was identified in aquatic organisms. The results provide support for further study on the environmental properties and biological transmission of PCBs.

ZrO2 Nanoparticles and Poly(diallyldimethylammonium chloride)-Doped Graphene Oxide Aerogel-Coated Stainless-Steel Mesh for the Effective Adsorption of Organophosphorus Pesticides.

A novel sorbent based on the ZrO2 nanoparticles and poly(diallyldimethylammonium chloride)-modified graphene oxide aerogel-grafted stainless steel mesh (ZrO2/PDDA-GOA-SSM) was used for the extraction and detection of organophosphorus pesticides (OPPs). Firstly, the PDDA and GO composite was grafted onto the surface of SSM and then freeze-dried to obtain the aerogel, which efficiently reduced the accumulation of graphene nanosheets. It integrated the advanced properties of GOA with a thin coating and the three-dimensional structural geometry of SSM. The modification of ZrO2 nanoparticles brought a selective adsorption for OPPs due to the combination of the phosphate group as a Lewis base and ZrO2 nanoparticles with the Lewis acid site. The ZrO2/PDDA-GOA-SSM was packed into the solid-phase extraction (SPE) cartridge to extract OPPs. According to the investigation of different factors, the extraction recovery was mainly affected by the hydrophilic-hydrophobic properties of analytes. Effective extraction and elution parameters such as sample volume, sample pH, rate of sample loading, eluent, and eluent volume, were also investigated and discussed. Under the optimal conditions, the linearity of phoxim and fenitrothion was in the range of 1.0–200 μg L−1, and the linearity of temephos was in the range of 2.5–200 μg L−1. The limits of detection were ranged from 0.2 to 1.0 μg L−1. This established method was successfully applied to detect OPPs in two vegetables. There was no OPP detected in real samples, and results showed that the matrix effects were in the range of 46.5%–90.1%. This indicates that the ZrO2/PDDA-GOA-SSM-SPE-HPLC method could effectively extract and detect OPPs in vegetables.

Purification Technology of Polysaccharides from Lophatherum gracile Brongn. by Macroporous Resin Adsorption and Its Effect on Athletic Endurance of Mice

The purified technological parameters of polysaccharide extract from Lophatherum gracile Brongn was optimized, and its effect on athletic endurance was observed. The best type of macroporous resin was selected through performance comparison of static adsorption and elution experiments, then the effects of sample solution pH, sample concentration, loading speed, sample volume, volume fraction of eluent, dosage of eluent and flow rate of elution on the dynamic purification effect were analyzed. Meanwhile, purified product on the influence of athletic endurance of mice was investigated by loading swimming test and related biochemical index detection. The results showed that the optimum purification process parameters were as follows: The initial concentration of sample solution was 5 mg/mL, the sample volume was 60 mL with loading speed of 2.0 mL/min, the pH value of sample solution was 5.0, and the volume fraction of ethanol was 80%, the eluent volume was 160 mL with flow rate of 1.0 mL/min. The purity of polysaccharide in product increased from 16.39% to 57.35%. Compared with the blank control group, the purified product groups at middle and high doses significantly prolonged exhaustive swimming time (P<0.05, P<0.01), enhanced activity of lactic dehydrogenase(P<0.05, P<0.01), decreased lactic acid and urea nitrogen content (P<0.05, P<0.01) after exercise. Therefore, polysaccharide of Lophatherum gracile Brongn. could preferably improve athletic endurance in body.

Sample preparation optimization by central composite design for multi class determination of 172 emerging contaminants in wastewaters and tap water using liquid chromatography high-resolution mass spectrometry

Multi-residue analysis is highly desirable for water quality control. To this end, a comprehensive workflow for the quantitative analysis of 172 anthropogenic organic compounds belonging to emerging contaminants (pharmaceuticals and personal care products, illicit drugs, organophosphate flame retardants and perfluoroalkyl substances) has been developed for application to wastewater and tap water, based on solid phase extraction (SPE) and Orbitrap high resolution mass spectrometry (HRMS). Due to the large number of analytes with various physicochemical characteristics that should be efficiently extracted, the response surface methodology (RSM) employing a central composite design (CCD) and desirability function (DF) approach was exploited to optimize the sample preparation process, instead of the conventional single-factor analysis. The factors included in the design of experiments (DoE) were sample pH, eluent solvents composition and volume. Statistical analysis (ANOVA) proved the adequacy of the proposed model (2- factor interaction) as p-value < 0.05 followed by different diagnostic tests confirmed the good fitting. The best values to acquire DF close to 1 were pH 3.5, methanol/ethyl acetate ratio 87:13 and eluent volume 6 mL. The streamlined method was validated in terms of accuracy, linearity, method limits, reproducibility, and matrix effect. The proposed workflow combines sensitivity and robustness, with recoveries over 70%, method quantification limits <1 ng/L, and relative standard deviations <20% for most of the compounds. Slight matrix effect (ME) was observed for most of PPCPs, IDs and PFAs, in contrast with most of the OPFRs, for which strong ME was calculated. Method applicability was tested over wastewater collected from a municipal wastewater treatment plant in Thessaloniki (Greece), revealing the presence of 69 and 40 compounds in influents and effluents, respectively, at varying concentrations.