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The silicon-aluminum ratio of the molecular sieves is a crucial control index for the quality of synthetic molecular sieves. Here a fast, simple and reliable sample preparation method, referred to as pouring and curing method, is described for determining the silicon-aluminum ratio of high silicon molecular sieves by energy dispersive x-ray fluorescence (EDXRF). Resin is used as the carrier with the addition of a curing agent, so that the sample powder is embedded in the resin matrix. By measuring sixteen random positions of the same cured sample, the homogeneity of the sample was evaluated to ensure the stability of the results. A double logarithmic calibration curve of the analysis line ratio and the corresponding concentration ratio of silicon and aluminum was established according to the binary ratio method. The results by EDXRF and inductively coupled plasma-optical emission spectrometer (ICP-OES) were compared with a relative standard error from 2.934 to 6.777%. The good precision shows that the pouring and curing method is a suitable for measuring the silicon-aluminum ratio of molecular sieves. [ABSTRACT FROM AUTHOR]

The calligraphy on Xuan paper written by Cao Hongxun, who was a scholar at the end of the Qing Dynasty, was comprehensively characterized using various analytical techniques in order to provide support for further conservation. Fourier transform infrared (FTIR) spectroscopy was used to identify the type of oil in the stains. The color difference, acidity, microstructure and elemental composition of the paper areas with and without the oil stains were analyzed and characterized using colorimetry, pH measurements, and scanning electron microscope-energy dispersive spectrometry (SEM-EDS), respectively. Paper fibers were observed using SEM and an optical microscope after dying with Herzberg stain. The results demonstrate that the stain in this paper artifact is mineral oil and the paper was produced using softwood, paper mulberry and herb fibers. A large color difference, lower pH and changes in the carbon ratio were present in the oil stains. However, the stains did not affect the elemental composition of the paper. Overall, this study provides evidence for further conservation treatment, such as selecting proper paper and cleaning reagents for the stains. [ABSTRACT FROM AUTHOR]

Spatial heterodyne Raman spectroscopy has been widely applied in various fields due to its non-contact, nondestructive, fast, high stability, and high spectral resolution characteristics. This article integrated spatial heterodyne Raman spectroscopy with chemometric methodologies to assess the feasibility of peak-to-peak ratio regression, partial least squares regression, support vector machine regression, and non-negative matrix factorization for the quantitative analysis of mixtures. Chemometrics methods were used to model and analyze the interference data in the interferogram domain, and variational mode decomposition was used to extract features from the interference data, further improving the interference data's modeling and prediction accuracy. The results demonstrate that modal intensities obtained through variational mode decomposition of interference data improve the prediction accuracy of regression analysis. Support vector regression exhibited the most favorable predictive performance among the tested models. The root mean square error of cross-validation was reduced from 5.55% to 2.64%, and the prediction root mean square error was reduced from 5.08% to 1.5%. The improved model utilizing interference data showed higher fitting accuracy and more precise sample predictions compared to spectral data modeling. [ABSTRACT FROM AUTHOR]

A urea-based covalent organic polymer (UCOP), was synthesized using 1,4-phenylene diisocyanate (PPDI) and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) trianiline (TTTA) and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nitrogen adsorption-desorption isotherm analysis. The prepared material was employed as an adsorbent for pipette tip–solid-phase extraction (PT–SPE) for benzimidazoles before high-performance liquid chromatography–tandem mass spectrometry analysis (HPLC–MS). The parameters affecting the isolation efficiency, including salt concentration, sample pH, mass of adsorbent, and types and volumes of eluent, were optimized. Using these conditions, PT–SPE provided good linearity from 0.1 to 10 μg kg−1 with low limits of detections (LODs) of 0.02 μg kg−1 together with good precision (relative standard deviations from 4.2 to 8.3%) and accuracy (recoveries from 76.2 to 84.8%). The results demonstrate that the urea-based covalent organic polymer has the potential for the enrichment of trace benzimidazoles. [ABSTRACT FROM AUTHOR]

Oil-based drilling cutting pyrolysis doped orange biochar composite (ODPR-OP) was prepared by the pyrolysis of oil-based drilling cuttings and orange peels (OP) for the adsorption of Cu (II) and Pb (II). The physical and chemical properties of the surface were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and the zeta potential. In addition, the adsorption capacity of the ODPR-OP biochar for Cu (II) and Pb (II) removal from aqueous solutions was investigated. The results show that the ODPR-OP biochar has a lower contact angle, smaller pore size, and higher micropore volume than either oil-based drilling cutting pyrolysis residues (ODPR) or orange-peel biochar, indicating a synergistic effect of co-pyrolysis for enhanced adsorption. Kinetic studies showed that the adsorption of Cu (II) and Pb (II) on ODPR-OP was explained better with the pseudo-second-order kinetic model. The adsorption equilibrium of Cu (II) and Pb (II) was compatible with the Langmuir isotherm, and the maximum monolayer adsorption capacities of the ODPR-OP biochar for Cu (II) and Pb (II) were 95.11 mg/g and 164.08 mg/g, respectively, which are higher than for ODPR or OP. In conclusion, the ODPR-OP composite has great potential for practical Pb (II) and Cu (II) removal from wastewater. [ABSTRACT FROM AUTHOR]

A paper spray tandem mass spectrometric (PS-MS/MS) method without column separation was developed for the rapid screening of clonidine in dietary supplements. PS-MS/MS provided acceptable performance compared to high-performance liquid chromatography – tandem mass spectrometry (HPLC-MS/MS) in terms of limits of detection and quantification, accuracy, and precision. To overcome ionization suppression of complicated plant-based pharmaceutical products, nizatidine, tizanidine, and apraclonidine were investigated as internal standards. A more similar structured internal standard is most suitable for matrix effect compensation. The developed method has advantages of simplicity and speed for the screening of clonidine in dietary supplements. [ABSTRACT FROM AUTHOR]

Near-infrared luminescence glutathione-coated gold nanoparticles (NGS-AuNPs) were synthesized and employed as fluorescent probes for the selective determination of hydrogen peroxide and glucose. This approach was based upon the coordination-induced fluorescence quenching of tris(2-carboxyethyl)phosphine (TCEP) with the NGS-AuNPs and its reduction of H2O2. The NGS-AuNPs possessed a highly monodispersed spherical morphology with a uniform diameter of 2.1 ± 0.5 nm and a maximal fluorescence emission wavelength of 810 nm. The results of the H2O2 determination demonstrate the excellent selectivity of this strategy with a limit of detection of 5.4 μM. This system was also employed for the selective determination of glucose which generated H2O2 by the catalytic oxidation of glucose oxidase with a limit of detection of 0.42 μM. This strategy exhibited excellent performance for the test of H2O2 and glucose in urine with recoveries from 93% to 103%. This methodology may allow the analysis of biological samples and clinical diagnosis. [ABSTRACT FROM AUTHOR]

Total vaporization (TV) headspace (HS) gas chromatography (GC) is reported for the determination of ethanol in flavor oil microcapsules. Fifteen microliters of sample were placed in a headspace sample vial and a near-complete mass transfer of ethanol from the liquid phase to the vapor phase was obtained within one minute at 105 °C. This approach allowed the determination of ethanol in the sample by gas chromatography. Under the optimal conditions, the performance of this method was investigated, showing good linearity and a low limit of quantification equal to 8.95 mg/L. The relative standard deviation was less than 3.3%, and the recovery ranged from 95.4% to 101.3%. The method was efficient, accurate, and suitable for the quality control determination of ethanol in oil phase systems. [ABSTRACT FROM AUTHOR]

Alkaline phosphatase (ALP) is a significant biomarker of diseases, such as osteoblastic bone cancer, hepatitis, and myeloma, and hence its determination is essential and important. MnO2/Mn2+ conversion-based magnetic relaxation sensing was developed to directly determine ALP in blood. In the presence of ALP, 2-phospho-L-ascorbic acid trisodium salt was catalyzed to produce ascorbic acid (AA), which reduced MnO2 to Mn2+, causing transverse relaxation time (T2) decay. A linear relationship of ALP from 5 mU·L−1 to 500 mU·L−1 with T2 signal and a low limit of detection (LOD) of 3.32 mU·L−1 were obtained using the optimized conditions of 200 µM of ascorbic acid-phosphate (AAP), 10 µg·mL−1 of MnO2, 37 °C, pH 7.4, and a 30 min reaction time. When directly measuring ALP in serum with the proposed method, the recoveries were from 99.2% to 101.3%, in accordance with values obtained by a commercial assay. In conclusion, a sensitive one-step method for ALP in complex samples was established which has potential for clinical applications. [ABSTRACT FROM AUTHOR]

ATP is related to the occurrence of many diseases, its facile, sensitive and accurate determination in real samples is needed for disease screening and treatment. Although some methods realized the sensitive detection of ATP using the signal amplification of cyclic reactions or nanoparticles, complex experimental processes limit their applications. In this paper, we report a simple surface plasmon resonance (SPR) method based on a single stranded DNA probe. The probe has dual recognition sites of ATP and Ag+; namely the ATP aptamer located in the middle of the probe and five cytosine (C) at both ends of the probe. In the absence of ATP, the probe transforms into a rigid hairpin structure by forming C-Ag+-C structures and produces a large SPR signal. However, once the probe interacts with ATP, three-dimensional structures are formed, and then the Ag+-induced probe configuration change is smaller, resulting in an small SPR signal. The signal difference before and after the probe interacts with ATP is proportional to the analyte concentration. The probe configuration change is in the optimum area for SPR detection, ensuring the sensitive ATP determination. The signal difference has a linear response with the logarithm of ATP concentration from 0.05 to 500 nM with a detection limit of 15 pM. Moreover, the strategy was demonstrated to determine ATP in serum samples with satisfactory recoveries. The results show that this simple and sensitive method has potential applications for clinical ATP determination. [ABSTRACT FROM AUTHOR]

A miniature atomic emission spectrometry (AES) was developed using a liquid cathode glow discharge (LCGD) as an excitation source and optical fiber spectrometer as the detection system. The instrument was employed for the sensitive determination of lithium (Li). The addition of 0.15% cetyltrimethylammonium chloride (CTAC), 0.15% cetyltrimethylammonium bromide (CTAB) and 3 critical micelle concentration (CMC) Triton X-405 enhanced the Li emission by 3.7-, 3.2-, and 1.8-fold, respectively. The presence of 50 mg L−1 Al3+ and SO42− inhibited the recovery of 0.5 mg L−1 Li about 73% and 75%, respectively. After adding CTAB, CTAC, and Triton X-405, the recovery of Li was from 98% to 108%, suggesting that the addition of surfactant eliminated the Al3+ and SO42− interferences. The sensitivity of Li was improved by adding the surfactants by factors of 2.3 for 0.15% CTAB, 2.0 for 0.15% CTAC, and 1.9 for 3 CMC Triton X-405. The limit of detection (LOD) with 0.15% CTAB for Li was 0.55 μg L−1 which was improved by 5.6-fold. In addition, the energy consumption was below 60 W and good precision was obtained. The accuracy, reliability, and repeatability of the proposed method were verified by analysis of water samples and satisfactory recoveries between 91% and 115% were obtained. The results demonstrate that LCGD-AES with surfactants can be used for highly sensitive determination of Li in complex samples because of its low cost, small size, and low power consumption. [ABSTRACT FROM AUTHOR]

Accurate modeling of near-infrared spectroscopy (NIRS) data is not easy, especially for automatic and optimal analysis, since it includes multiple steps and many algorithms and parameters in each step. Even the order of the methods for pretreatment affects the outcomes of models. In this work, a novel strategy is reported to discover the suitable parameters for data pre-processing and variable selection with the help of particle swarm optimization (PSO). Using the optimization process of 14 parameters for pre-processing and two parameters for variable selection as examples, it reduces the experience required for NIRS modeling and helps to construct partial least squares (PLS) quantitative models with significant improvement. This approach promotes the use of NIRS after simplifying the process to construct ideal models. In this study, three NIRS spectra of flavors and fragrances and 13 corresponding physical and chemical indices were applied to characterize the strategy. Simultaneous modeling of PSO global optimization and traditional methods were comprehensively investigated for comparison, in which the indices R2, Q2, RMESC and RMSECV were employed for evaluation. The average values were 0.89, 0.88, 0.29 and 0.47 by the former, and 0.86, 0.66, 0.36 and 0.57 by the latter. Almost all the former modeling results were better than the latter. This fully demonstrates that the proposed method is powerful for NIRS data analysis. [ABSTRACT FROM AUTHOR]

Attenuated total reflection (ATR) – Fourier transform infrared (FTIR) spectroscopy with the pretreatment of converting the absorption spectrum into angle spectrum (CASAS) and partial least squares (PLS) was employed to rapidly and simultaneously determine the ingredients of cellulose slurries and solutions during lyocell production. ATR was employed to rapidly and conveniently collect the spectra of the swollen slurries and viscous solutions during production. CASAS was used to eliminate the influence on modeling by the optical path differences due to uneven ingredient distributions in the samples. The PLS models for the cellulose, water, and N-methylmorpholine N-oxide (NMMO) concentrations of the cellulose slurry/solution were constructed using the raw spectra, pretreated spectra by CASAS, and common pretreatment methods, respectively. The results show that CASAS eliminates interferences due to the differences in optical path and improves the performance of PLS model for each analyte. The standard errors of prediction (SEP) of models using CASAS for cellulose, NMMO, and water concentration of cellulose slurry were 0.368, 0.196 and 0.171, while the values for the cellulose solution were 0.442, 0.353, and 0.066, respectively. The standard errors of prediction (SEPs) of CASAS models are significantly lower than the reproducibility requirement of the reference method, 0.5. The reported approach using ATR-FTIR spectroscopy combined with CASAS and PLS is rapid and accurate for determining the ingredients of the cellulose slurries and solutions and offers potential for identifying similar samples. [ABSTRACT FROM AUTHOR]

Cysteine (Cys) is a crucial biomarker and plays various significant roles in many physiological and pathological processes. Here is reported a fluorescent probe Mito-cys by incorporating o-chlorobenzoic acid ester onto a hemicyanine platform. The probe exhibited excellent specificity and rapid response for cysteine. The developed method quantitatively monitored cysteine from 5 μM to 30 μM with a detection limit of 135 nM. The probe was also employed to image trace endogenous cysteine in living HeLa cells. [ABSTRACT FROM AUTHOR]

AbstractFibroblast activation protein (FAP) plays an important role in the progress of lung cancer, but an effective tool has not been reported for revealing the relationship between them. In this work, an adenosine-5-triphosphate (ATP)-powered signal-amplified probe, named ASAP, was prepared using a FAP-sensitive polymer and ATP-binding fluorophore. This probe was employed to determine FAP based upon signal amplification. In the living cells, the activated polymer is destroyed by FAP and the internal fluorophor is released, causing the first stage of signal amplification. Furthermore, the free fluorophor can bind with endogenous ATP to enhance the fluorescence intensity, realizing the second stage of amplification. By virtue of the double amplification, FAP was determined from 0 to 50 ng/mL with a detection limit of 0.26 ng/mL. Moreover, cell imaging showed that the endogenous FAP was successfully imaged in lung carcinoma cells with ASAP, demonstrating the relationship between FAP and lung cancer. [ABSTRACT FROM AUTHOR]

S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) play an important role in various biochemical reactions involving the maintenance of human health and disease prevention. In this study, an accurate, rapid, economical, and simple protocol is reported for the simultaneous determination of the SAM and SAH concentrations in human urine. 97% trifluoroacetic acid (0.05%) was used in the mobile phase as a micromolecule ion-pairing agent in order to enhance the formation of ion pairs and the protonation of the SAM and SAH analytes. Following solid phase extraction (SPE), the separation of SAM and SAH was performed by micromolecule ion pair chromatography using a C18 column. Three types of solid phase extraction columns were characterized for the purification of the urine samples, and their correlative mechanisms were evaluated in detail. Good linearity values were obtained across the concentration ranges from 0.5 to 60 μmol/L and 0.1 to 10 μmol/L for SAM and SAH, respectively. The limits of detection were equal to 0.006 and 0.01 μmol/L for SAM and SAH, respectively, while the limits of quantitation were 0.02 and 0.04 μmol/L for these analytes. The intra-day and inter-day precision values for the determined SAM and SAH species were less than 1.38. The recovery values of SAM and SAH in urine were between 83.65 and 98.41%. Thus, this method has demonstrated to be suitable for the determination of SAM and SAH in human urine. [ABSTRACT FROM AUTHOR]

Short-chain fatty acids (SCFAs) are carboxylic acids that contain fewer than six carbons and are the metabolites of the intestinal flora. SCFAs participate in almost all circulatory system components and regulate the physiological functions of an organism. In addition, these compounds are recognized to be important components in gut homeostasis and metabolic disease occurrence. The comprehensive analysis of SCFAs in feces is challenging due to their large polarity differences, wide concentration range and the complex matrix. Most of the existing analytical methods require complicated derivatization operations, which require reagents that harm both humans and the environment. In this study, we have optimized pretreatment conditions and developed a simple, rapid, and safe method to accurately quantify seven common SCFAs in feces by gas chromatography – mass spectrometry (GC-MS). In brief, the feces samples were freeze-dried, extracted with saturated sodium chloride solution, acidified with sulfuric acid, and extracted with ethyl acetate. Following dehydration with anhydrous sodium sulfate, the supernatant was harvested and analyzed by GC-MS. The methodological investigation results showed that the method has excellent linearities with determination coefficients (R2) exceeding 0.99. In addition, the recovery values, matrix effects, precision, and stability of the method meet the requirements for biological sample analysis. Seven primary SCFAs, including acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, and hexanoic acid, were identified and quantified in the feces samples. In conclusion, a rapid and accurate method was developed for the simultaneous determination of seven SCFAs in feces that was successfully applied to type 2 diabetic (T2DM) rats and drug therapy. [ABSTRACT FROM AUTHOR]

The nitrogen–sulfur co-doped carbon dots (CDs) were synthesized using scallion leaves via an environmentally friendly and facile hydrothermal method, which did not require surface passivating agents. When the hemin concentration was increased from 0.5 to 10.0 μM, the fluorescence emission intensity of the CDs was also linearly quenched. The detection limit was estimated to be 0.1 μM. The fluorescence sensing mechanism was systematically explored by a series of characterization methods. The results revealed that the fluorescence sensing quenching mechanism was ascribed to the inner filter effect and photo-induced electron transfer. The proposed mechanism was further verified by our theoretical calculations. The proposed sensor was successfully applied for the determination of hemin in human serum samples. [ABSTRACT FROM AUTHOR]

A hollow anode-solution cathode glow discharge (HA-SCGD) was designed as a plasma excitation source for optical emission spectrometry. The operation parameters such as the discharge current, argon flow rate and solution flow rate were investigated. The spatial distribution profiles of normalized results of spectral bands and spectral lines were investigated and analyzed. The detection limits of Na, Li, K, Ca, Mg, Pb, Sr, Mn, Rb, Cs and Zn were 0.22, 0.69, 1.33, 240.37, 21.55, 529, 619.43, 209.51, 2.94, 7.13 and 206.95 µg L−1, respectively. The repeatability, expressed as the relative standard deviation for these elements, was determined to be within the range from 0.53 to 2.70%. The Ca, Fe, K, Mg and Na concentrations in a certified reference material were quantitatively analyzed, and the results obtained by the HA-SCGD system agreed well with the reference values. The results show that the HA-SCGD system accurately and stably determined metals in aqueous solution. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) were determined in 36 fish samples near a deca- brominated diphenyl ether (deca-BDE) production facility in Weifang City, Shandong Province, China. The concentrations of PBDEs in fish muscle and liver samples were from 45.8 to 560 ng g−1 lipid weight (lw) and 327 to 2120 ng g−1, lw, respectively. The highest concentration of PBDEs was found in carp with a mean value of 1370 ng g−1, lw, followed by crucian with a mean of 1030 ng g−1, lw, and grass carp with a mean of 681 ng g−1, lw. Relatively constant congener patterns were observed among the fish species. BDE-47 was the most predominant congener with contributions of 50.1% to 89.7% to the total PBDE concentrations. Different BDE-99/BDE-100 ratios were observed, indicating that the PBDE pattern is species-dependent. [ABSTRACT FROM AUTHOR]

A novel ensemble-based feature selection method was developed which is designated as ensemble partial least squares regression coeffientents (EPRC). It was composed of two steps: generating a series of different single feature selectors and aggregating them to reach a consensus. Specifically, the bootstrap resampling approach was used to generate a diversity of single feature selectors, and the absolute values of the regression coefficients of the partial least squares (PLS) model were used to rank the features. Next, these feature rankings out of single feature selectors were aggregated by the weighted-sum approach. Finally, coupled with the regression model, the features selected by EPRC were evaluated through cross validation and an independent test set. By experiments of constructing the spectroscopy analysis model on three near infrared spectroscopy (NIRS) datasets, it was shown that the EPRC located key wavelengths, gave a promotion to regression performance, and was more stable and interpretable to the domain experts. [ABSTRACT FROM AUTHOR]

Nanosized surface-enhanced Raman scattering (SERS) substrates fabricated by the controlled growth of metal nanostructures on water-dispersed two-dimensional nanomaterials can open a new avenue for SERS analysis of liquid samples in biological fields. In this work, regular and uniform Ag nanostructures were grown on the surface of graphene oxide (GO) through a microwave-assisted hydrothermal method. Polyamidoamine (PAMAM) dendrimers were assembled on the surface of GO to form GO/PAMAM templates for growing Ag nanostructures, which are primarily comprised of Ag dimers and trimers. The prepared Ag/GO nanocomposites are highly dispersed and stable in aqueous solution and may be used as substrates for enhanced Raman detection of rhodamine 6 G (R6G) in aqueous solution. This special substrate provides high-performance SERS and suppresses R6G fluorescence in aqueous solution and is promising as a nanosized material for the enhanced Raman detection of liquid samples in biological diagnostics. [ABSTRACT FROM AUTHOR]

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin elicits many harmful effects in tissues. Metabolomic changes and the associated pathway alterations caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin in the cerebellum, an area thought to be less affected by environmental alterations, remain unknown. Here, metabolomics was performed to identify endogenous metabolites that were associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin in the cerebellum of 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated mice using Fourier transform ion cyclotron resonance mass spectrometry. Distinct peaks were located in two mass ranges, 210 m/z–420 m/z and 450 m/z–570 m/z. In principal component space, the high-dose group was clearly separated from the control group. Six metabolites associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin dose were identified. The metabolite 1-palmitoyl lysophosphatidic acid increased with increasing doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin, indicating activation of the rat sarcoma pathway. Biosynthesis of the unsaturated fatty acid 18-hydroxyoleate was inhibited upon 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. The decrease in N-arachidonoyl taurine, implies that taurine increased, suggesting inhibition of neuronal signal transmission. A decrease in N-acetyl-aspartyl-glutamate has been associated with injury of the cerebellum through activation of N-methyl-D-aspartic acid receptors. An increase in glycerophosphoinositol suggests damage to blood–brain barrier function, and changes in purine metabolism were observed because inosine increased following 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. These results suggest that 2,3,7,8-tetrachlorodibenzo-p-dioxin activates the rat sarcoma pathway, alters fatty acid biosynthesis and purine metabolism, inhibits neurotransmitter systems, and is harmful to blood–brain barrier function in the cerebellum. [ABSTRACT FROM PUBLISHER]

Neutral desorption-extractive electrospray ionization mass spectrometry was used for the direct, rapid, and quantitative determination of chlorpyrifos in honey without pretreatment. Under the optimized conditions, the limit of detection was 1.64 ng/mL with a linear dynamic range from 10 to 1,000 ng/mL and relative standard deviations from 1.97 to 6.14%. The recoveries of fortified honey samples at 50 and 500 ng/mL were 82.02 and 109.28% with relative standard deviations of 4.02 and 4.34%, respectively. This protocol offers high sensitivity, good precision, rapid analysis, and high specificity in a complex matrix. [ABSTRACT FROM PUBLISHER]

Surface molecularly imprinted polymers for mezlocillin were used for the selective solid-phase extraction of mezlocillin from eggs. The molecularly imprinted polymers were prepared using mezlocillin as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, silica particle as the support and were characterized by infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The adsorption properties of polymers were investigated in detail. The obtained polymers provided high imprinting efficiency to mezlocillin with an imprinting factor of 3.72 and were used as selective sorbents for mezlocillin. Molecularly imprinted solid-phase extraction followed by high-performance liquid chromatography was used for the determination of mezlocillin in eggs and the conditions were evaluated. The average recovery of mezlocillin in fortified eggs was between 69.8 and 82.3% with a relative standard deviation less than 6.9%. The results demonstrate the application of molecularly imprinted polymers for the extraction of mezlocillin from biological samples. [ABSTRACT FROM AUTHOR]

The differentiation of aromas of Chinese liquor is important for their unique flavors. In this work, aromas of Chinese liquor were characterized by gas chromatography and chemometrics. Ten representative aroma compounds, including three alcohols, four esters, two organic acids, and acetal in 16 Chinese liquor were determined by gas chromatography with flame ionization detection. The relationship between these compounds and six classic aromas was investigated using principal component analysis andk-means clustering. The cumulative contribution of the first three principal components reached up to 84.607%, which effectively differentiated the liquors. The variables with the highest loading absolute value were acetal and ethyl acetate for principal component 1, ethyl butanoate and ethyl hexanoate for principal component 2, and the hexanoic acid and ethyl butanoate for principal component 3. The aromas of the liquors were characterized byk-means clustering with the first three principal component scores, indicating that the acetal, ethyl acetate, ethyl butanoate, ethyl hexanoate, and hexanoic acid are important for the aroma of Chinese liquors. This work demonstrated that the gas chromatography with chemometrics is effective for the characterization of aromatic liquor. [ABSTRACT FROM PUBLISHER]

A novel sensitive and simple electrochemical DNA sensor is reported for the determination of p53 tumor suppressor gene. A gold nanoparticle/graphene nanocomposite-modified glassy carbon electrode was prepared and methylene blue was used as the hybridization redox indicator. Scanning electron microscopic and electrochemical characterization demonstrated that the gold nanoparticles and graphene were present on the electrode. The resulting sensor provided suitable electrochemical response to the p53 tumor suppressor gene with a linear dynamic range from 0.1 to 1000 nM. The limit of detection was 0.012 nM. The sensor was able to differentiate a complete complementary DNA sequence, single-base mismatched DNA sequence, and a three-base mismatched DNA sequence. The precision of the device was satisfactory, with a relative standard deviation of 4.1% for 11 measurements. The combination of gold nanoparticles and a graphene nanocomposite provided enhanced capabilities for the determination of DNA for clinical applications. [ABSTRACT FROM PUBLISHER]

Interest in ionic liquids (ILs) for their potential in analytical chemistry is increasing because they are environmentally benign and are good separation solvents. The aim of the presented investigation was to verify whether ILs would be a suitable background electrolyte (BGE) in nonaqueous capillary electrophoresis (NACE) for organic cations analysis of the closely related analogues. In this study, a novel and very simple NACE method has been established for analyzing seven quaternary alkaloids in Coptis rhizome using 1-alkyl-3-methylimidazolium tetrafluoroborate-based ionic liquid as BGE. The effects of the alkyl group, imidazolium counterion (anionic part), along with the concentration of IL, are investigated and discussed. Baseline separation, high efficiencies, and symmetrical peaks of the seven alkaloids were obtained. The separation mechanism could be hydrophobic and hydrogen-bonding interactions between the alkaloids and the imidazolium cations. The optimum conditions were 70 mM 1-decyl-3-methylimidazolium tetrafluoroborate (1D-3MI-TFB) methanol solution (apparent pH 2.66) and 30 kV applied voltage. The detection was performed at 254 nm. Seven quaternary alkaloids in Coptis rhizome were separated within 14 min. The proposed NACE separation procedure is highly reproducible and can be applied in the qualitative and quantitative analysis of Coptidis alkaloids. [ABSTRACT FROM AUTHOR]

The growth and reproduction of phytoplankton are controlled by macronutrients. Phytoplankton communities are important indicators of marine responses to environmental changes. Thus, it is important to study the relationships between phytoplankton composition and macronutrient concentrations. High performance liquid chromatography (HPLC) coupled with electrospray ionization/triple quadrupole mass spectrometry (MS) was used for the determination of 13 pigments of phytoplankton taxa. Based on the pigments and optimized formulas for algae biomass conversion, the contributions of diatoms, dinoflagellates, chrysophytes, haptophytes, cyanobacteria, chlorophytes, prasinophytes, and cryptophytes to the total phytoplankton biomass were evaluated. The highest concentrations of pigments were found in the phytoplankton community treated with nitrogen/phosphorus/silicon for 9 days. By monitoring cholorophyll a in eight taxa, the phytoplankton biomass was found to increase in the following order: control>silicon>nitrogen/phosphorus/silicon. Diatoms/fucoxanthin and chlorophytes/lutein were the major phytoplankton present in the community. [ABSTRACT FROM PUBLISHER]

The objective of this study was to develop a novel and effective method for the evaluation of the postmortem interval using infrared microspectroscopy. Postmortem rat liver samples were investigated at 10, 20, and 30°C. Time-dependent changes in the images were observed from variations in the spatial distribution in the liver tissue that were correlated with the postmortem interval. This relationship, which has not been reported previously, offers a novel approach to supplement conventional forensic methods. [ABSTRACT FROM PUBLISHER]

Manganese-doped zinc sulfide quantum dot based molecularly imprinted polymer composite nanoparticles were prepared. Bisphenol A served as the template and 3-aminopropyltriethoxysilane and tetraethoxysilicane were the functional monomer and cross-linker, respectively. The quantum dots exhibited excellent selectivity, fast adsorption kinetics, high stability, and good dispersion in aqueous media. The quenched fluorescence emission was proportional to the concentration of Bisphenol A without any preconcentration. This highly selective fluorescence sensor had a linear response from 10 to 700 nanograms per milliliter with a correlation coefficient of 0.9860. The relative standard deviation of five replicate measurements of 100 nanograms per milliliter Bisphenol A was 2.2 percent. The recovery of fortified Bisphenol A in water samples ranged from 98.70 to 105.50 percent. [ABSTRACT FROM PUBLISHER]

A novel procedure to fabricate a nonenzymatic hydrogen peroxide sensor was developed based on a silver-poly (amide amine) dendrimer nanocomposite synthesized by a microwave procedure. The formation of silver nanoparticles functionalized with the poly (amide amine) dendrimer was confirmed by ultraviolet visible spectroscopy, high resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The electroanalytical properties of a glassy carbon electrode modified with the silver-poly (amide amine) dendrimer nanocomposite were evaluated by the determination of hydrogen peroxide. The electrochemical sensor exhibited rapid response and high sensitivity to hydrogen peroxide with a linear dynamic range from 1.0 × 10–5 to 3.7 × 10–3 molar (r = 0.998) and a limit of detection of 5.06 micromolar. The sensitivity was 30.24 microampere · per millilmolar per square centimeter and the response time was three seconds at a working potential of −0.35 volt. In addition, the sensor was unaffected by the presence of ascorbic acid, citric acid, and oxalic acid. These results indicate that the silver-poly (amide amine) dendrimer nanocomposite based sensor has application for the determination of hydrogen peroxide. [ABSTRACT FROM PUBLISHER]

Microwave, ultrasonic, and reflux extraction were compared to provide an optimized method for flavonoids from Radix Scutellariae including the antioxidant activity of the extracts. The antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl and oxygen radical absorbance capacity assays. Baicalin, wogonoside, baicalein, wogonin, and oroxylin A were quantified using ultra-high performance liquid chromatography. For microwave extraction, with a ten minutes treatment, the extraction efficiencies of the analytes were higher than treatments by refluxing for 180 minutes and sonication for sixty minutes. In addition, the antioxidant activity of the microwave extracts was slightly higher than the extracts obtained by the other methods. Microwave extraction conditions were further optimized by a single-factor experiment and the optimum conditions were 50 percent ethanol–water (volume by volume), an extraction temperature of 100 degrees celsius, an extraction time of ten minutes, and a sample to solvent ratio of 1:50. This study combines extraction, phytochemistry, and bioactivity to screen the most efficient extraction procedure for flavonoids from Radix Scutellariae. [ABSTRACT FROM PUBLISHER]

Sodium hexametaphosphate was shown to form a complex with acridine orange by electrostatic interactions that induce fluorescence quenching. Analysis of fluorescence intensity showed that the process was dominated by static quenching, which was confirmed by absorption spectra and lifetime of the excited state. The decreased fluorescence intensity was directly proportional to the concentration of sodium hexametaphosphate between 8.0 × 10−7and 1.1 × 10−5 mol L−1with a limit of detection of 5.3 × 10−7 mol L−1. Beverages were analyzed for sodium hexametaphosphate with recoveries between 91.7% and 108.3%. [ABSTRACT FROM AUTHOR]

A detailed study of the supramolecular self-assembly of a cyanine amine derivative upon a variety of templates was conducted including investigation of charge properties, the rigidity of templates, and solubility. The amine derivative exhibited strong self-assembly on negatively-charged templates such as carboxymethyl amylose and carboxymethyl cellulose, and generated red-shifted absorption and enhanced fluorescence, which are characteristics of J-aggregation. Much less self-aggregation was observed for lower negatively-charged templates such as hyaluronic acid. The rigidity of templates had a great impact on self-aggregation in terms of no appreciable J- or H-aggregation observed on rigid Laponite clay. Cyanine amine existed in the molecular state with self-aggregates. For the carboxymethyl cellulose/cyanine amine system, the order of mixing each component impacted the aggregation of cyanine amine: carboxymethyl cellulose to cyanine amine mainly led to J-aggregation. In contrast, H-aggregation was dominant in cyanine amine to carboxymethyl cellulose. [ABSTRACT FROM AUTHOR]

Near infrared spectroscopy in combination with appropriate chemometric methods is an effective technique for quantitative analysis of parameters of interest for the pharmaceutical industry. In this study, the artificial neural network (ANN) was applied to monitor critical parameters (compression force, tablet hardness, mean particle size, and active pharmaceutical ingredient concentration of tablets) in the process of naproxen pharmaceutical preparation. The performance of ANN was compared to linear methods (partial least squares regression (PLS) and synergy interval partial squares (siPLS)). The ANN models for compression force, tablet hardness, mean particle size, and active pharmaceutical ingredient concentration of tablets yielded the low root mean square error of prediction (RMSEP) values of 0.936 KN, 0.302 kg, 4.49 mg, and 2.14 µm, respectively. The predictive ability of the PLS model was improved by siPLS with selection of spectral regions and the best performance among all calibration methods was showed by the nonlinear method (ANN). Effective models were built by using these approaches using near infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Anthraquinones are active components of herbal medicine, and consequently it is necessary to develop a selective, convenient, and green preconcentration method for these compounds. A rhein-functionalized resin was synthesized by a condensation reaction followed by characterization by infrared spectroscopy, transmission electron microscopy, solid carbon-13 nuclear magnetic resonance, and elemental analysis. The rhein-functionalized resin was employed for solid-phase extraction with HPLC-MS for the determination of anthraquinones in the extracts ofPolygonum cuspidatum. Emodin, chrysophanol, and physcion were selectively concentrated by a simple absorption and desorption procedure. The results indicated that this new material has application for separating and enriching anthraquinones from herbal medicine, which is significant for pharmaceutical analysis. [ABSTRACT FROM AUTHOR]

A facile method based on liquid chromatography coupled with triple quadrupole mass spectrometry was established to determine floridoside and isofloridoside in red algae. Correlation coefficients of the calibration curves were larger than 0.9989, indicated good linearity. Detection limits of floridoside and isofloridoside were 0.05 and 0.20 ng/mL, respectively, and the limits of quantification were 0.1 and 0.4 ng/mL. The recoveries varied from 75.7% to 76.8%, and relative standard deviations of inter-day and intra-day precision were lower than 8.5% (n = 5). The effects of sea level variations in the intertidal zone on the osmotic role of floridoside and isofloridoside concentrations in seven red algae were investigated. It was shown that algae that inhabit higher levels in the intertidal zone contained higher concentrations of floridoside and isofloridoside. The results suggest that the presence of direct sun, exposure time, and temperature influenced to the concentrations of floridoside and isofloridoside due to the osmotic pressure adjustments. [ABSTRACT FROM AUTHOR]

This study employed near-infrared (NIR) spectroscopy to analyze content uniformity, moisture content, compression force, tablet hardness, average particle size, and particle-size distribution. The content uniformity, moisture content, compression force, tablet hardness, and average particle size models yielded high correlation coefficients (R2) of 0.99582, 0.99725, 0.99620, 0.96294, and 0.98421, respectively, whereas the particle size distribution models showed good predictive ability. Conventional criteria such as R2, root-mean-square error of calibration, and the root-mean-square error of prediction were used to evaluate the accuracy and precision of the model. To ensure the accuracy and predictability of the content model for low-dose tablets, additional validation and reliability evaluations were performed using 70%, 80%, 100%, 120%, and 130% drug concentrations as well as 90% and 110% active content formulations. Near-infrared spectroscopy with multivariate modeling is a rapid, nondestructive technique for the characterization of the manufacturing process. [ABSTRACT FROM AUTHOR]

The separation of a molecularly imprinted polymer for cordycepin was investigated. The synthesis employed cordycepin as the molecular template, alpha-methylacrylic acid as the functional monomer, glycol dimethyl acrylate as the cross-linking agent, azobisisobutyronitrile as the initiator, and tetrahydrofuran as the solvent and pore-foaming agent. The interaction between cordycepin and the functional monomer was investigated by ultraviolet-visible and infrared spectroscopy. The properties of the molecularly imprinted polymer were analyzed by scanning electron microscopy, equilibrium adsorption experiments, and the Scatchard equation. Static adsorption, solid phase extraction, and high-performance liquid chromatography experiments were employed to evaluate the adsorption properties and selective recognition characteristics. The results showed that the molecularly imprinted polymer had specific adsorption with cordycepin, and the maximum absorption capacity was 1920 µg/g. Scatchard analysis suggested that high affinity and low affinity binding sites were present. For the high affinity case, the dissociation constant and apparent maximum numbers of the binding sites were 0.0089 mmol/L and 4.78 µmol/g, respectively. The dissociation constant and apparent numbers of binding sites were 0.035 mmol/L and 6.047 µmol/g for the low affinity sites. Compared with the corresponding nonimprinted polymer, the cordycepin molecularly imprinted polymer exhibited higher adsorption and selectivity for cordycepin than structural analogs. [ABSTRACT FROM AUTHOR]

Impedance detection on adherently growing cells by micro-electrodes provides useful analytical methods for cancer research. Colon adenocarcinoma is one of the most common types of gastrointestinal cancer. To improve the survival rate of colon adenocarcinoma patients, chemotherapy becomes more and more important among the standard clinical treatments. In this study, a cell based-biosensor was developed to determine the cytotoxicity of therapy medicines to colorectal cancer using the LS180 cell line. By analyzing the varying parameters in the membrane and cell nucleus in an impedance circuit model, the anticancer mechanisms of the drugs were deduced by impedance sensing. By real-time monitoring of the biosensor, time- and concentration- dependent impedance changes were detected under treatment medicines, such as oxaliplatin, 5-fluorouracil, and the more effective combination regimen. The cell-based biosensor combined with circuit modeling provides a promising approach for drug screening and developing new therapeutic regimens with anticancer medicines. [ABSTRACT FROM PUBLISHER]

The electrochemical behavior of 304-stainless steel in solutions with different pH values and chloride concentrations was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and a nonlinear Mott-Schottky analysis method. The results showed that the corrosion behavior of 304-stainless steel was affected by various factors, such as pH, chloride ion concentration, and dissolved oxygen. The pit initiation and propagation stage were observed in EIS plots through the addition of sodium chloride. In addition, the effect of pH on the passive film dominated one of the film growth kinetic reactions. The effect of chloride ion concentration was caused by the generation of more cation vacancies, leading the passive film more susceptible to pitting, which was also demonstrated by X-ray Photoelectron Spectroscopy. The results are consistent with the point defect model. [ABSTRACT FROM PUBLISHER]

Reflectance spectroscopy has been widely applied in the field of environmental studies. In this study, a low-cost, rapid, and nondestructive method using spectral reflectance was explored to evaluate protein concentrations in plant leaves ofEuonymus japonica. Proteins in leaf samples were extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and five specific protein bands of interest were identified and quantified. Correlation analysis indicated that spectral reflectance had significant relationships with ribulose bisphosphate carboxylase a (r = −0.43) and chlorophyll a-b binding protein (r = 0.53). A linear regression model and a quadratic regression model were formulated to directly and rapidly estimate the concentration of these two proteins withR2 = 0.61 and 0.7, respectively. To more accurately estimate the concentration of proteins, a precise inversion was established by a back propagation neutral network model using plant spectral absorption and position parameters, and theR2values for proteins ribulose bisphosphate carboxylase, chlorophyll a-b binding protein, oxygen evolving enhancer protein, and ATP synthase subunit beta were 0.90, 0.91, 0.91, and 0.93, respectively. The models established in this study were shown to be useful tools for studies of plant biochemical components and health under different environmental conditions. [ABSTRACT FROM PUBLISHER]

Snake venom contains bioactive materials for drug development, diagnosis, and treatment. After separating and purifying the kallikrein-like enzyme (AHP-Ka) fromAgkistrodon halys pallasvenom for the first time, a monoclonal antibody against AHP-Ka was prepared and characterized. An indirect sandwich enzyme-linked immunosorbent assay (ELISA) based on the monoclonal antibody was developed and validated for the pharmacokinetic analysis of AHP-Ka in rat plasma. The method was calibrated using rat plasma and 1:100 dilution of plasma was selected to prepare a calibration curve to validate the precision, accuracy, and stability of the ELISA method. A good linear relationship was obtained in a working range from 3.9 ng/mL to 62.5 ng/mL with a limit of detection of 2.94 ng/mL. Intra- and inter-batch precision were less than 10%. The average recovery ranged from 94.6% to 104.4% in rat plasma at the concentrations of 5 ng/mL, 15 ng/mL, and 45 ng/mL, respectively. The ELISA method was successfully used for the pharmacokinetic study of AHP-Ka in Sprague-Dawley rat plasma after intravenous administration. The work is expected to contribute to future preclinical development of AHP-Ka. [ABSTRACT FROM PUBLISHER]

A simple and rapid discrimination of four lung cancer related volatile organic compounds (VOCs) was achieved with a novel colorimetric sensor array. Based on the cross-responsive mechanism, the sensor system exhibited high sensitivity to selected lung cancer biomarkers, includingp-xylene, styrene, isoprene, and hexanal with concentrations varying from 50 ppb to 500 ppb. By extracting color information, it provided good selectivity and fine discrimination of selected gases via pattern recognition with Fisher linear discriminant (FLD). Additionally, with the employment of the Takagi-Sogeno Fuzzy Neural Network (TSFNN), different concentrations of selected VOCs were discriminated. It also suggested that the colorimetric sensor array proposed could not only distinguish different lung cancer related VOCs but also discriminate specific VOCs of different concentrations with an average rate of classification up to 95%. Our preliminary study demonstrated that the cross-responsive sensor array had infinite potential for further clinical and commercial use for early diagnosis of lung cancer. [ABSTRACT FROM PUBLISHER]

A method was employed to determine enantiomeric excess (ee) value of chiral tert-butoxycarbonyl (Boc-protected) amino acids in a rapid way by using an infrared spectroscopy technique combined with wavelet packet transform (WPT) and least squares support vector machines (LS-SVM). Infrared spectral data were decomposed by using WPT algorithm. Simulated annealing (SA) algorithm was then used to search the optimal decomposed frequency band that had the greatest contribution to the quantitative analysis of ee values. As a result, the band (7, 34) with 34 variables and the band (5, 1) with 116 variables were determined as the optimal ones for the determination of Boc-protected proline and alanine, respectively. The selected variables in the optimal band were used as the inputs of LS-SVM models. The spectral variables selected by the WPT-SA method had lower predicting errors than full range spectra and the spectral variables selected by some traditional variable selection methods. Reasonable good results with root mean-square error of prediction (RMSEP) of 7.51 and 3.80 were obtained for the determination of ee values of two Boc-protected amino acids, showing that it is possible to rapidly determine ee values of amino acids by using IR spectroscopy rapidly. [ABSTRACT FROM AUTHOR]

In order to study the regional distribution, characterization, and possible source of Cadmium in the eastern Tibetan Plateau, samples of leaves, xylem, twigs, bark, and roots of timberline forest trees (fir or spruce) and soils at depths from 0 to 40 cm were collected in eight sites in Hengduan Mountains. According to Cd contents, organs and tissues were divided into three groups: the highest-level organ (roots: 0.237 mg · kg−1), the high-level organ/tissue (bark: 0.183 mg · kg−1and twigs: 0.159 mg · kg−1), and the low-level organ/tissue (xylem: 0.054 mg · kg−1and leaves: 0.048 mg · kg−1). Cd contents in Transect A were a little higher than Transect B. Sites near pollutant sources and high-levels are more sensitive to Cd pollution and accumulated more Cd, while Cd contents in sites far away from pollutant sources and low-level organ/tissue were relatively low. It is suggested that the eastern Tibetan Plateau has already been polluted by the influence of general circulation to some extent. Nevertheless, low Cd contents in some sites prove that high mountains may barricade Cd pollutants from monsoon. [ABSTRACT FROM PUBLISHER]

The electrochemical behavior of field-exposed 304 stainless steel in a marine atmospheric environment and its simulated solutions were studied by corrosion rates test, cyclic anodic polarization (CAP), electrochemical impedance spectroscopy (EIS), and scanning Kelvin probe (SKP). The morphology, composition, and structure of the rust were analyzed by different methods: SEM, EDS, and Raman spectroscopy. The electrochemical experiments showed that the exposure samples in the marine atmosphere-simulated solution have a characteristic of lower pitting potential, and the stability of passive film became weak with exposure time extension. The corrosion products of 304 stainless steel in Xisha marine atmosphere are mainly the β-FeOOH, γ-Fe2O3,and Fe3O4. The Kelvin potential of the samples’ surface declined after 12 months exposure and tends to be uneven. [ABSTRACT FROM PUBLISHER]

In this work, an improved hydride-generation atomic fluorescence spectrometry (HG-AFS) method for the determination of total arsenic (As) in wastewater and sewage sludge samples was applied. The samples were digested completely with mixtures of HNO3 and HClO4. Analytical conditions were studied and optimized through uniform experimental design U*10(108) combined with a single factor test. A mathematical model was established, and a quadratic polynomial stepwise regression analysis by using the DPS software was employed to obtain the factors that impact the fluorescence intensity. This technique is then combined with a single factor test. The optimized experimental conditions were obtained as follows: PMT voltage was 305 V, lamp current was 70 mA, KBH4 concentration was 2.0% (m/v), carrier liquid (HCl) concentration was 5% (v/v), carrier gas (Ar) flow rate was 300 mL min−1, and reaction acidity was 10% (v/v) HCl. The pre-reduction of all forms of As to As(III) was performed by using a mixed solution of 1% thiourea and 1% ascorbic acid. The content of total As was determined under the optimized experimental conditions. The detection limits for total As in wastewater and sewage sludge were 0.09 µg L−1 and 0.01 mg kg−1, respectively. The linear ranges were 0.24–100 µg L−1, and the recovery was 91.0–102.0%. The relative standard deviation (RSD, n = 5) for eleven replicate measurements of the certified reference materials containing 60.6 ± 4.2 µg L−1 As (certified sample of water) and 10.7 ± 0.8 mg kg−1 As (certified sample of soil) were 3.1% and 1.6%, respectively. The proposed method was validated by the analysis of certified reference materials and was successfully applied to the determination of total As in real samples of wastewater and sewage sludge with satisfactory results. [ABSTRACT FROM AUTHOR]

A novel voltammetric sensor using multi-wall carbon nanotubes (MWNTs) coupled with Nafion modified glassy carbon electrode (GCE) was developed for the detection of methylparaben (MP). The sensor exhibited good electrocatalytic activity toward the oxidation of MP in the phosphate buffer solution (PBS, pH 6.5). It displayed good sensitivity, repeatability, reproducibility, and long-term stability. Under the optimized conditions, the anodic peak current was linear with the concentration of MP in the range of 3 × 10−6 mol L−1 to 1 × 10−4 mol L−1. The detection limit was 1 × 10−6 mol L−1. The proposed method was successfully applied to determine MP in cosmetics with satisfactory results. [ABSTRACT FROM AUTHOR]