Discrimination of the species and authenticity of Rhizoma Coptidis based on stable isotope and multielement fingerprinting and multivariate statistical analysis.

It is essential to be able to identify the source species and to determine the authenticity of traditional Chinese medicines (TCM) in order to prevent the use of false or inferior medicines. In this work, a stable and reliable method of discriminating among the three source species of Rhizoma Coptidis and checking the authenticity of Rhizoma Coptidis samples was established. The technique involved evaluating stable isotope ratios and the contents of multiple elements in samples along with the use of multivariate statistical techniques. The stable isotope ratios δ13C, δ15N, δ2H, and δ18O and the concentrations of various inorganic elements (Li, B, Na, Mg, Al, P, Si, K, Ca, Ti, Mn, Fe, Cu, Zn, Sr, and Ba) in authentic Rhizoma Coptidis samples from three source species (n = 56) and in counterfeit Rhizoma Coptidis samples (n = 39) were determined. The results showed that there were significant differences between the samples from different source species according to multivariate statistical analysis. The three species were clearly distinguished using hierarchical cluster analysis (HCA). Employing stepwise linear discriminant analysis (SLDA), a classification model for differentiating the three species was developed, and this model achieved 100% classification accuracy when applied to samples. In addition, authentic samples and counterfeit samples were successfully discriminated using stable isotope and multielement fingerprint analysis and orthogonal projections to latent structures discriminant analysis (OPLS-DA), and OPLS-DA models for checking the authenticity of Rhizoma Coptidis were established and verified. Therefore, stable isotope and multielement analysis combined with multivariate statistical analysis was shown to be a promising method of discriminating among the three source species of Rhizoma Coptidis and of establishing the authenticity of Rhizoma Coptidis samples. Graphical abstract.

Establishment of a Multiplex Real-Time TaqMan-MGB Polymerase Chain Reaction (PCR) Method for the Simultaneous Detection of Three Animal Chlamydia Species.

BACKGROUND Chlamydiae are spread globally and cause infectious diseases in both humans and animals. The existing detection methods for this disease have numerous shortcomings, including low sensitivity, time consuming procedures, and high contamination vulnerability. MATERIAL AND METHODS To overcome shortcomings for detecting animal chlamydiosis, a multiplex quantitative polymerase chain reaction (PCR) assay was established for simultaneously detecting and differentiating 3 Chlamydia species (C. pecorum, C. abortus, and C. psittaci) by real time PCR based on TaqMan-MGB technology. RESULTS The limit of detection was 20.2 copies/µL for Chlamydophila (Cp.) abortus, 30.8 copies/µL for Cp. pecorum, and 16 copies/µL for Cp. psittaci. This method has good repeatability and stability as coefficients of variation range from 0.04% to 1.38%. Furthermore, compared with OIE (World Organization for Animal Health) recommended PCR assay and previously reported animal chlamydia shell PCR, this multiplex PCR assay demonstrated 99% concordance in detecting clinical samples of porcine nasal swabs and vaginal swabs. CONCLUSIONS The novel established method in this study was able to detect 3 types of Chlamydia species simultaneously, and had high sensitivity, strong specificity, and good stability. It provided a rapid, reliable, and convenient method for epidemiological and clinical diagnosis of chlamydiosis in animals.

Cost-efficient magnetic nanoporous carbon derived from citrus peel for the selective adsorption of seven insecticides.

A magnetic solid-phase extraction adsorbent that consisted of citrus peel-derived nanoporous carbon and silica-coated Fe3 O4 microspheres (C/SiO2 @Fe3 O4 ) was successfully fabricated by co-precipitation. As a modifier for magnetic microspheres, citrus peel-derived nanoporous carbon was not only economical and renewable for its raw material, but exerted enormous nanosized pore structure, which could directly influence the type of adsorbed analytes. The C/SiO2 @Fe3 O4 also possessed the advantages of Fe3 O4 microspheres like superparamagnetism, which could be easily separated magnetically after adsorption. Integrating the superior of biomass-derived nanoporous carbon and Fe3 O4 microspheres, the as-prepared C/SiO2 @Fe3 O4 showed high extraction efficiency for target analytes. The obtained material was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and the Brunauer-Emmett-Teller method, which demonstrated that C/SiO2 @Fe3 O4 was successfully synthesized. Under the optimal conditions, the adsorbent was selected for the selective adsorption of seven insecticides before gas chromatography with mass spectrometry detection, and good linearity was obtained in the concentration range of 2-200 µg/kg with the correlation coefficient ranging from 0.9952 to 0.9997. The limits of detection were in the range of 0.03-0.39 µg/kg. The proposed method has been successfully applied to the enrichment and detection of seven insecticides in real vegetable samples.

Matrix effects in the determination of ß-receptor agonists in animal-derived foodstuffs by ultra-performance liquid chromatography tandem mass spectrometry with immunoaffinity solid-phase extraction.

Matrix effects in determination of three ß-receptor agonists including salbutamol (SAL), clenbuterol, and terbutaline in animal-derived foodstuffs were studied by ultra-performance LC-MS/MS with cleanup of immunoaffinity SPE column (IAC). Some animal tissue samples including pig liver, swine muscle, and fish muscle were hydrolyzed by the mixed enzyme solution or HCl solution, and the cleanup efficiencies with SAL IAC, MCX SPE column, and C(18) -SCX tandem columns were examined and compared by using spiked experiments. The results showed that the matrix effects in the determination of SAL and terbutaline can be eliminated with SAL IAC cleanup, and the average recoveries of SAL were 77.4~81.5%, 79.0~80.3%, and 85.0~87.2% in pig liver, swine muscle, and fish muscle, respectively. The decision limit (ccα) and detection capability (ccß) for SAL in pig liver were 0.02 and 0.05 µg/kg, respectively.

Enhanced adsorption of 3,4-methylenedioxymethamphetamine by magnetic graphene oxide-polydopamine nanohybrid modified zeolitic imidazolate framework-67 and its micro-mechanism: Experiments and calculations.

Exploring the structure-dependent adsorption mechanism of contaminants in wastewater is beneficial to high-efficiency adsorbents design and environmental remediation. In this study, emerging porous material of zeolitic imidazolate framework-67 (ZIF-67) has been modified by the magnetic graphene oxide-polydopamine nanohybrid (mGOP) to obtain three-dimensional ZIF-67/mGOP through an in-situ growth strategy, which was applied to adsorb 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") in wastewater. A combination of characterizations, experiments (pH, humic acid and ion strength effect) and quantum chemical calculations revealed the microscopic adsorption mechanism involves each single component, of which the hydrogen bond (O/N…HO) and π-π electron donor acceptor (π-π EDA) interactions of mGOP endowed favourable adsorption of ZIF-67/mGOP, and mechanisms of the pore filling and Co-O chelation of ZIF-67 played synergistic effect. Such nanocomposite as a ZIFs-based adsorbent exhibited ultra-high porosity (total pore volume = 0.4033 cm3/g) and specific surface area (995.22 m2/g), revealed the heterogeneity and multilayer adsorption properties, and obtained a theoretical maximum adsorption capacity of 159.845 µg/g which higher than that of mZIF-67 alone. Overall, this work provided an effective strategy for rationally modulate ZIFs-based composites and exploration of adsorption mechanism.

Multifunctional magnetic chitosan-graphene oxide-ionic liquid ternary nanohybrid: An efficient adsorbent of alkaloids.

A magnetically and recyclable multifunctional nanohybrid adsorbent (IL-Fe3O4@SiO2@CS/GO) with chitosan, graphene oxide and ionic liquid was prepared by glutaraldehyde cross-linking reaction, acylation reaction and directly grafted method. The incorporation of CS, GO and IL could collaboratively enhance adsorption for 5 alkaloids. The Box-Benhnken design was applied to optimize the experimental parameters affecting the extraction efficiency. The adsorption kinetic was further used to describe the adsorption process, revealing alkaloids adsorption was a chemisorption process, which was well represented by pseudo-second-order model. Concerning the equilibrium behavior, the adsorption was multilayer and heterogeneous adsorption that satisfactorily modeled by the Freundlich model. Under optimal conditions, good adsorption capacity for morphine, codeine, ephedrine, amphetamine and benzoylecgonine (7.2, 8.4, 9.2, 5.8 and 11.2 mg g-1, respectively) were obtained via multiple mechanisms to attain simultaneous extraction of alkaloids. Accordingly, IL-Fe3O4@SiO2@CS/GO nanohybrid adsorbent could be extended as a potential adsorbent for extraction of illicit additives in food samples.

Enhanced adsorption of malathion and phoxim by a three-dimensional magnetic graphene oxide-functionalized citrus peel-derived bio-composite.

By integrating the steps of direct magnetization and one-pot pyrolysis, a three-dimensional (3D) magnetic graphene oxide-functionalized citrus peel-derived bio-composite (mGOBC) was synthesized and characterized successfully, and it was proved to possess a three-dimensional (3D) porous architecture and graphitic structure. Its potential as an enrichment adsorbent was investigated using adsorption kinetics and adsorption isotherm models to establish an effective analytical method for the determination of organophosphorus pesticides (OPPs) in vegetables. The experimental results indicated that the adsorption was better fitted with the pseudo second order model and Langmuir isotherm model, and the maximum adsorption capacities for malathion and phoxim were 25.26 mg g-1 and 42.31 mg g-1, respectively. It was found that the graphitic structure of mGOBC resulted in π-π EDA (electron donor-acceptor) interaction with the benzene rings, electron-donating N, P, and S atoms in the analytes, which assisted adsorption. Subsequently, Plackett-Burman (P-B) experimental design, central composite design (CCD) and response surface methodology (RSM) were employed to develop an analytical method based on the mGOBC adsorbent. Under optimal conditions, the developed method is accurate and precise. The novel synthesized mGOBC can efficiently achieve removal and trace determination of harmful OPPs.

One-step fabrication of alkali-acid modified three-dimensional magnetic biochar for the determination of pesticides in pigment-rich vegetables.

Magnetic biochar was successfully synthesized via a one-step method through simultaneous activation and magnetization with alkali-acid modified citrus peel as the raw material, which could effectively penetrate interfering substances. The characterization analysis showed that the magnetic biochar exhibited high graphitic degree, higher specific surface area and smaller pore diameter, which resulted in superior adsorption performance. The magnetic biochar was used as an adsorbent for the cleanup and extraction of 22 pesticides (consisting of insecticides, fungicides and herbicides) from vegetables and the quantitative detection was completed by gas chromatography-mass spectrometry (GC-MS). The Plackett-Burman experimental design (PBD), central composite design (CCD) and response surface methodology (RSM) were employed to identify significant factors and optimal experimental conditions. Under optimal conditions, the methodological linearity was in the range of 1-100 µg kg-1 with the coefficients of determination ranging from 0.9969-0.9999, while the limits of detection (LODs) and limits of quantification (LOQs) were 0.31-0.91 µg kg-1 and 1.03-3.05 µg kg-1, respectively. The recoveries of the analytes from spiked samples were in the range of 78.1-112.5%. It was confirmed that the method established by using magnetic graphitic biochar as the adsorbent is an efficient pretreatment procedure and could be successfully applied for analysis of food safety.

Chitosan functionalized magnetic graphene oxide nanocomposite for the sensitive and effective determination of alkaloids in hotpot.

Chitosan functionalized magnetic graphene oxide nanocomposite (Fe3O4@SiO2@CS/GO) was successfully fabricated via a facile amide reaction between chitosan and graphene oxide. A novel extraction method using Fe3O4@SiO2@CS/GO as nanoadsorbent was developed and applied to the efficient extraction and determination of multiple alkaloids from the complex matrix. The composition and structure of the nanoadsorbent was systematically characterized by various techniques. The nanoadsorbent possesses performances of high efficiency, easy operation, superparamagnetism, environment friendly and economic feasibility. The adsorption mechanism for alkaloids included π-π electron-donor-acceptor interaction, cation-π interaction and hydrogen bonding. The principal parameters influencing extraction procedure such as adsorbent dosage, pH, adsorption time, desorption conditions and regeneration cycles were investigated and optimized. Under the optimized conditions, the method exhibited good linear dynamic range with correlation coefficient (r2) higher than 0.997 and the limit of detection (LOD) was among 0.016--0.092 µg kg-1. Intra- and inter-day relative standard deviations (RSDs) were <10%. These results indicated that the developed method was successfully applied for simultaneous detection of alkaloids in hotpot. This study provided valuable guidance and effective method for the analysis of alkaloids in intricate interference system.

A three dimension magnetic bio-char composite-based quick, easy, cheap, effective, rugged and safe method for multi-pesticides analysis of vegetables.

To improve the efficiency of high-throughput analysis, a three-dimensional (3D) magnetic Fe3O4-biochar composite was synthesized and used as adsorbent of QuEChERS pretreatment method for the analysis of 49 pesticide residues in vegetables containing complex pigments. The structure evolution mechanism of Fe3O4-biochar was discussed and the structural morphology was confirmed by a series of characterization methods. Multivariate approach was employed to optimize the extraction parameters including sample amount, solvent volume, NaCl amount, extraction time, anhydrous MgSO4 amount, adsorbent amount, purification time. The results revealed that extraction time and Fe3O4-biochar amount had significant influences on the recovery yield of pesticides and the 20 min extraction time and 13.9 mg Fe3O4-biochar are optimal conditions. Under these conditions, the Fe3O4-biochar exhibited better cleanup of matrix co-extracts than conventional adsorbents, which reduced matrix effect and simplified extraction process. Moreover, the adsorption mechanism was further probed and turned out that the aromatic sheets on Fe3O4-biochar dominated the π-π EDA (electron donor-acceptor) interaction for interfering substances. The proposed extraction method exhibited good linearity with correlation coefficient greater than 0.9902. The limits of quantitation (LOQs) were in the range of 0.03-0.67 µg kg-1. The average recoveries were between 81.3% and 117.3% with relative standard deviation (intra-day RSD = 0.5-7.5% and inter-day RSD = 0.6-6.9%). All results highlighted the excellent potential of Fe3O4-biochar strategy in analysis of pesticide residues in vegetables containing complex pigments.

A novel Fe3O4/graphene oxide/citrus peel-derived bio-char based nanocomposite with enhanced adsorption affinity and sensitivity of ciprofloxacin and sparfloxacin.

To create more active adsorption sites on biochar, the Fe3O4/GO/citrus peel-derived magnetic bio-nanocomposite (mGOCP) with hierarchically porous architectures was synthesized by a facile one-pot hydrothermal approach for efficient removal of fluoroquinolone antibiotics ciprofloxacin (CIP) and sparfloxacin (SPA). The characterization analysis of bio-nanocomposites showed that the incorporation of GO could ensure relatively higher surface area (1556 cm2 g-1), more abundant pore structure, and higher thermal stability within mGOCP bio-nanocomposites than Fe3O4/citrus peel-derived magnetic bio-nanocomposites (mCP). And the mGOCP-1% attained outstanding adsorption capacity for CIP (283.44 mg g-1) and SPA (502.37 mg g-1), respectively. The primary adsorption mechanisms for CIP and SPA included π-π electron donor-acceptor interaction, H-bonding, hydrophobic interaction and electrostatic interaction. Overall, the surface morphology and structural composition of biochars could be regulated with GO to facilitate the adsorption capacity. Moreover, the developed mGOCP could be extended as a potential adsorbent for removal of other emerging organic pollutants in water.

A high efficient adsorbent for plant growth regulators based on ionic liquid and ß-cyclodextrin functionalized magnetic graphene oxide.

Four types of ionic liquids which composed of cation with imidazole ring and anion with benzene, naphthalene, anthraquinone and naphthoquinone ring were prepared and named VOIm+BenSO3-, VOIm+NapSO3-, VOIm+AQSO3- and VOIm+NQSO3-, respectively. Then, ionic liquids and ß-cyclodextrin functionalized magnetic graphene oxide materials were firstly synthesized for the extraction of 23 plant growth regulators in vegetable samples. The synthesized materials anticipated the unique properties of ionic liquids, ß-cyclodextrin, graphene oxide and Fe3O4@SiO2, including high surface area, high supramolecular recognition capability, superparamagnetism and large delocalized π-electron system, which were successfully characterized. Among four kinds of ionic liquids functionalized adsorbents, the VOIm+AQSO3- modified material exhibited high adsorption capability to 7 plant growth regulators compared with Fe3O4@SiO2/GO/ß-CD, Fe3O4@SiO2/GO and other three types of ionic liquids based adsorbents. Parameters that could affect the recoveries of 7 plant growth regulators were investigated, such as mass ratio of Fe3O4@SiO2/GO/ß-CD to ionic liquids, salt concentration, pH, amount of adsorbent, extraction time and desorption solvent. Under the optimal condition, the magnetic solid phase extraction method using VOIm+AQSO3- and ß-cyclodextrin functionalized magnetic graphene oxide material (Fe3O4@SiO2/GO/ß-CD/IL) as adsorbent was developed and coupled with ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry for the determination of 7 plant growth regulators in vegetable samples. Validation results showed that the limit of detection and limit of quantitation were in the range of 0.01-0.18 µg/kg and 0.03-0.58 µg/kg, respectively. The satisfactory linearities were acquired in the concentration of 2-50 µg/kg with the correlation coefficients higher than 0.9982. Taken together, the synthesized Fe3O4@SiO2/GO/ß-CD/IL was a highly effective magnetic solid phase extraction adsorbent for the enrichment of trace level of plant growth regulators in vegetable samples.

Controllable synthesis of magnetic nanoporous carbon with tunable porosity for the efficient cleanup of vegetable samples.

Highly graphitic nanoporous carbon (NPC) was obtained from an agricultural waste-citrus peel at optimum condition. Then, a low-cost and pore size-controlled magnetic graphitic nanoporous carbon (MNPC) with ultrahigh specific surface area (1064 m2 g-1) was successfully fabricated by coprecipitation of Fe3O4 particles onto NPC. The prepared MNPC was characterized by Brunauer-Emmett-Teller (BET), Raman spectrum, scanning electron microscope (SEM) and Fourier transform infrared spectrometry (FT-IR). BET results showed a significant increase in the micropores volume and specific surface area of MNPCs following the increase of carbonization temperature, which implied that highly efficient carbonization made NPC an excellent active phase for MNPC. Besides, the adsorption mechanism was investigated and turned out that π-π interactions between interfering substances and MNPC were considered to be the major driving force for the adsorption process. The experimental parameters affecting the cleanup efficiency was optimized through Response surface methodology (RSM) in detail. Under the optimal cleanup condition, the MNPC was applied for determination of 16 insecticides in vegetables coupled with gas chromatography-mass spectrometry (GC-MS), a satisfactory performance was obtained. Good linearity was observed in the investigated concentration range of 1-100 µg kg-1 with correlation coefficients (r2) between 0.9963 and 0.9999. The limits of detection (LODs) were in the range of 0.03-0.33 µg kg-1. The recoveries ranged from 81.9 to 112.3% with relative standard deviations (RSDs) less than 10.9%. To summary up, the MNPC could potentially be used as a super adsorbent to efficiently remove pigments from vegetables, so that the proposed method was an efficient cleanup and enrichment procedure.

Fabrication of a high selectivity magnetic solid phase extraction adsorbent based on ß-cyclodextrin and application for recognition of plant growth regulators.

An adsorbent, consisting of silica-coated Fe3O4 grafted graphene oxide and ß-cyclodextrin (Fe3O4@SiO2/GO/ß-CD), which possessed the merits of antioxidation, superparamagnetism, high surface area, high supramolecular recognition and environment friendly, was successfully fabricated. Considering the synergy between ß-CD and graphene oxide in adsorption mechanism, the synthesized adsorbent could grasp compounds especially with aromatic structures through π-π interaction, hydrophobic interaction and host-guest inclusion complex forming. Based on the advantages, a magnetic solid phase extraction (MSPE) method for 9 PGRs using Fe3O4@SiO2/GO/ß-CD as adsorbents was developed in this study. The characterizations of Fe3O4@SiO2/GO/ß-CD were performed on Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), CHNS/O elemental analyzer, scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Under the optimal MSPE condition, the Fe3O4@SiO2/GO/ß-CD exhibited selectivity capability toward 9 PGRs when compared with Fe3O4@SiO2/GO. Meanwhile, the selectivity capability of Fe3O4@SiO2/GO/ß-CD was higher than that of Fe3O4@SiO2/GO/α-CD except for 4-FPA. When the developed MSPE procedure was coupled with ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UHPLC-QTrap-MS/MS) to quantitative analysis of 9 PGRs, linearities ranging from 2 to 50 µg/kg were achieved for 9 PGRs with the correlation coefficients (r2) in the range of 0.9975-0.9999. The limits of detection (LODs) for 9 analytes varied from 0.04 to 0.29 µg/kg. Finally, the proposed technique was applied to analyze PGRs residues in mutiple vegetable samples.

A novel magnetic ß-cyclodextrin modified graphene oxide adsorbent with high recognition capability for 5 plant growth regulators.

ß-Cyclodextrin (ß-CD) modified magnetic graphene oxide material (Fe3O4@SiO2/GO/ß-CD), a novel magnetic sorbent for enrichment and purification of plant growth regulators (PGRs) in vegetables prior to gas chromatograph mass spectrometer (GC-MS) detection, was successfully fabricated. The novel magnetic sorbent geometrically fitted to selectively recognize and enrich PGR analytes especially containing aromatic structure. The selectivity experiment demonstrated the higher selectivity of Fe3O4@SiO2/GO/ß-CD toward 5 PGR compounds than that of Fe3O4@SiO2/GO. Several parameters affecting extraction efficiency including the volume of extraction solvent, amount of adsorbent, extraction time, type and the volume of desorption solvent were optimized. Under the optimized condition, good linear relationships were obtained in the range of 1-100µg/kg with determination coefficients (R2) from 0.9983 to 0.9996. The limits of detection (LODs) of 5 PGRs were from 0.04 to 0.28µg/kg. The proposed method had good potential for the analysis of trace level of 5 PGRs in real vegetable samples.

[Rapid determination of spirotetramat and its metabolite residues in milk by ultra performance liquid chromatography-tandem mass spectrometry].

A method for the rapid and simultaneous determination of spirotetramat (BYI08330) and its four metabolites in milk was developed with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with acetonitrile for precipitating proteins, degreased with hexane, and analyzed by UPLC-MS/MS in positive electrospray ionization and multiple reaction monitoring (MRM) mode. Good linear relationships between peak areas and mass concentrations of the analytes were obtained in the range of 0.5-50 µ g/L with correlation coefficients greater than 0.998 (n=6). The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) were 0.05-0.30 µ g/L and 0.17-1.00 µ g/L, respectively. The recoveries at the spiked levels of 1.0, 2.0 and 10 µ g/L were in the range of 80.0%-108.8% with relative standard deviations (RSDs) of 4.8%-15.2% (n=6). The method is fast, sensitive and accurate, and can be used to simultaneously determine BYI08330 and its four metabolites in milk.

Simultaneous detection of 15 antibiotic growth promoters in bovine muscle, blood and urine by UPLC-MS/MS.

An analytical method was established for the rapid detection of antibiotic growth promoters (AGPs) in bovine muscle, and bovine blood and bovine urine, using ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). After the addition of an aqueous solution of EDTA-Na2, the pH of bovine urine samples was directly adjusted to 5.2 by acetic acid-ammonium acetate and purified by HLB solid-phase extraction cartridge; bovine muscle and bovine blood samples processing were extracted with acetonitrile (ACN) and ACNwater (90:10; v/v) without any purification step. The samples were then centrifuged, concentrated and analysed by UPLC-MS/MS on an ACQUITY UPLC® BEH C18 column using gradient elution. The developed method was validated and mean recovery percentages at three spiked levels were 74-119%, 76-115% and 76-119%, respectively, in bovine muscle, bovine blood, and bovine urine. The relative standard deviation (RSD) ranged from 1.0% to 14.7% in spiked bovine muscle, bovine blood and bovine urine. The limits of detection (LOD) of all analytes were in the ranges 0.11-3.82 µg kg-1, 0.10-2.49 µg kg-1 and 0.06-4.53 µg kg-1 in bovine muscle, bovine blood, and bovine urine, respectively. The method was sensitive, accurate and was applied to monitor real samples. To the best of our knowledge, this is first method available for simultaneous determination of several classes of APGs in bovine muscle, and bovine blood and bovine urine.

[Determination of 21 illegally added chemical drugs in health foods using ultra performance liquid chromatography-tandem mass spectrometry coupled with QuEChERS].

A method for the simultaneous determination of 21 illegally added chemical drugs in improving sleep and immunity health foods using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Oral liquid and health wine samples were shaken with acetonitrile and acetonitrile-water-formic acid (60:39:1, v/v/v), respectively, then purified by QuEChERS method. The extracts were separated on an Acquity UPLCTM BEH C18 column (50 mm×2.1 mm, 1.7 µm) with gradient elution of acetonitrile and 2 mmol/L ammonium acetate solution containing 0.1% (v/v) formic acid as mobile phases. The electrospray ionization in positive ion mode was used for analysis in multiple reaction monitoring (MRM) mode. The results showed that the target drugs had a good linear relationship in the range of 1-100 µg/L with the correlation coefficients (R2) ≥ 0.992. The limits of detection (LODs) and limits of quantification (LOQs) were 0.07-3.41 µg/kg and 0.22-11.36 µg/kg, respectively. The average recoveries of the 21 chemical drugs in oral liquid and health wine were in the range of 61.4%-116.5% and 67.4%-98.4% with the relative standard deviations (RSDs) of 0.2%-13.4% and 0.2%-11.8%, respectively. The developed method is sensitive and reliable. It has been successfully used for the detection of illegally added chemical drugs in real samples.

Rapid Determination of Dichlofluanid Residues in Vegetables Using Dispersive-SPE Sample Preparation Combined with Gas Chromatography-Mass Spectrometry.

A method for rapid determination of dichlofluanid residue in vegetables using dispersive solid-phase extraction (dispersive-SPE) sample preparation combined with gas chromatography-mass spectrometry (GC-MS) was developed. Samples were extracted with actone-ethyl acetate (1:1, V/V), and then detected by GC-MS with an external standard method after being purified by optimized primary secondary amine, graphitized carbon black and anhydrous magnesium sulphate (MgSO4). It turned out that dichlofluanid showed a good linearity (y= 2.7E+ 5x- 2710.5) over the range of 0.02-2.00 mg/L with a correlation coefficient of 0.9994. The limit of detection was 0.13 µg/kg (S/N = 3) and the limit of quantification was 0.43 µg/kg (S/N = 10). The recoveries of the dichlofluanid were in the range of 73.3-106.7, 83.3-116.7 and 83.3 ∼ 106.7% with the spiked levels of 0.01, 0.02 and 0.05 mg/kg, and the relative standard deviations were in the range of 4.1-22.3%. Compared with the reported literature, the method is more simple, rapid, sensitive, reliable and can be applied to many vegetables.

Preparation of size-controlled magnetite nanoparticles with a graphene and polymeric ionic liquid coating for the quick, easy, cheap, effective, rugged and safe extraction of preservatives from vegetables.

Size-controlled magnetite nanoparticles (Fe3O4) with 200-1000nm were synthesized by co-precipitation method. Then Fe3O4@SiO2@G@PIL was synthesized and used as modified QuEChERS adsorbent for the determination of preservatives in vegetables. The size of about 200nm of Fe3O4 in Fe3O4@SiO2@G@PIL was selected as optimum size to clean-up. It not only exerted the nanometer features of magnetic nanoparticles, but also displayed the large specific surface area of graphene (G) and the solvent effects of polymeric ionic liquids (PILs). Various experimental parameters have been investigated. Under the optimized conditions, a simple, rapid and effective method for the determination of 20 preservatives residues in vegetables was established by modified QuEChERS to gas chromatography/mass spectrometry (GC-MS) analysis. The good linearity with correlation coefficients (R(2)) of 0.9972-0.9999 was obtained over the range of 0.02-2.00mg/L for 20 preservatives. The detection limits of the proposed method for 20 preservatives ranged from 0.82 to 6.64µg/kg. The adsorbent was successfully applied for extraction and determination of preservatives in vegetable samples, which thus was time-saving with keeping good clean-up performance.