Three-birds-with-one-stone: An eco-friendly and renewable humic acid-derived material application strategy for macrolide antibiotic detection and multifunctional composite film preparation.

This research proposes a simple and novel strategy for the green detection of antibiotics along with the reduction of microplastic and humic acid (HA) hazards. The entire process is based on a single-step solvent-sieving method to separate HA into insoluble (IHA) and soluble (SHA) components, subsequently recombining and designing the application according to the original characteristics of selected fractions in accordance with the zero-waste principle. IHA was applied as a dispersive solid phase extraction (DSPE) sorbent without chemical modification for the enrichment of trace MACs in complex biological matrices. The recovery of MACs was 74.06-100.84 % in the range of 2.5-1000 µg∙kg-1. Furthermore, SHA could be combined with biodegradable polyvinyl alcohol (PVA) to prepare multifunctional composite films. SHA endows the PVA film with favorable mechanical properties, excellent UV shielding as well as oxidation resistance performance. Compared with pure PVA, the tensile strength, toughness, antioxidant and UV-protection properties were increased to 157.3 Mpa, 258.6 MJ·m-3, 78.6 % and 60 % respectively. This study achieved a green and economically valuable utilization of all components of waste HA, introduced a novel approach for monitoring and controlling harmful substances and reducing white pollution. This has significant implications for promoting sustainable development and recovering valuable resources.

A green and facile one-step hydration method based on ZIF-8-PDA to prepare melamine composite sponges with excellent hydrophobicity for oil-water separation.

Frequent crude oil spills and illegal discharges of industrial organic pollutants cause serious damage to the ecological environment and considerable loss of valuable resources. Therefore, there is an urgent need to develop efficient strategies to separate and recover oils or reagents from sewage. Herein, a green, facile and rapid one-step hydration method was applied to obtain the composite sponge (ZIF-8-PDA@MS) that monodispersed zeolitic imidazolate framework-8 nanoparticles with high porosity and large specific surface area were firmly loaded onto the melamine sponge by ligand exchange and the self-assembly of dopamine. The water contact angle of ZIF-8-PDA@MS with multiscale hierarchical porous structure could reach 162°, which remained stable over a long period of time and a wide pH range. ZIF-8-PDA@MS displayed excellent adsorption capacities (up to 85.45-168.95 g⋅g-1), and could be reused at least 40 times. Besides, ZIF-8-PDA@MS exhibited remarkable photothermal effect. Simultaneously, Silver nanoparticle-immobilized composite sponges were also prepared via in-situ reduction of silver ions to inhibit bacterial contamination. The composite sponge developed in this work can be used not only for the treatment of industrial sewage, but also for the emergency response of large-scale marine oil spill accidents, which has inestimable practical value for water decontamination.

Economical irregular silica as an effective dispersive solid-phase extraction sorbent for the quantification of calcitriol in soft capsules.

Calcitriol is an active product of vitamin D produced by the liver and kidney hydroxylase metabolism with strong physiological activity. It is the preferred form of medicine for patients with insufficient bone mineralization due to chronic kidney disease. Calcitriol soft capsule is one of the common preparation forms, the main drug content of which is very low (1.55 µg g-1), and the pharmaceutical excipients interfere greatly, especially the oily matrix medium-chain triglycerides. Therefore, removing the interference of oily matrix is ​​the main challenge in the content determination. At present, the commonly used sample purification method for the determination of calcitriol in soft capsules is liquid-liquid extraction, but it usually consumes a lot of toxic organic solvents and it is costly. The adoption of SPE purification method, on the one hand, requires specific experimental equipment, and on the other hand, the organic solvent used in the experiment may cause the dissolution of SPE column tube materials, which will interfere with the subsequent detection. Herein, in order to achieve a cost-effective and reliable determination of calcitriol soft capsule content, we developed a dispersive solid-phase (DSPE) extraction method that directly uses irregular silica as sorbent, which is followed by high-performance liquid chromatography equipped with a UV detector(HPLC-UV)analysis. Selective retention of calcitriol is achieved by the polar interaction between calcitriol and silica, what's more, sufficient contact between washing solvent and sorbent can be guaranteed. Therefore, after pretreatment with DSPE, the interference of oily matrix on detection can be mostly removed and then improve the accuracy of the method compared to the SPE method. Under the optimal conditions of DSPE, calcitriol showed a good linear relationship in the range of 0.15-2.99 µg g-1, the R2 was 0.997. Satisfactory recoveries ranging from 101.1%-102.0% for calcitriol were achieved in the oily matrix at the levels of 0.75, 1.50 and 2.24 µg g-1. And the intra-day and inter-day RSD were less than 2.5 % and 3.2 %. Meanwhile, the LOD and LOQ of calcitriol was 0.01 µg g-1 and 0.02 µg g-1, which is in full compliance with the regulatory level fixed by the EU, China or other countries. This method was further verified to determine the content of calcitriol in commercial calcitriol soft capsules and the recoveries of three batches of products was 86.2 %-94.4 %. Based on these characteristics, the proposed method makes it possible to determine the low content of weakly polar drugs in the oily matrix in a simple, low-cost and reliable way.

Application of core-satellite polydopamine-coated Fe3O4 nanoparticles-hollow porous molecularly imprinted polymer combined with HPLC-MS/MS for the quantification of macrolide antibiotics.

Core-satellite-structured magnetic nanosorbents (MNs) used for the selective extraction of macrolide antibiotics (MACs) were prepared in this study. The MNs (core-satellite polydopamine-coated Fe3O4 nanoparticles-hollow porous molecularly imprinted polymer) consisted of polydopamine-coated Fe3O4 nanoparticles (Fe3O4@PDA) "core" linked to numerous hollow porous molecularly imprinted polymer (HPMIP) "satellites" with bridging amine functional groups. It is worth mentioning that HPMIPs act as "anchors" for selectively capturing target molecules. Polymers were characterized using TEM, SEM, FT-IR, VSM, and TGA and applied as magnetic dispersive solid-phase extraction (MDSPE) sorbents for the enrichment of trace MACs from a complex food matrix prior to quantification by HPLC-MS/MS. Nanocomposites revealed outstanding magnetic properties (36.1 emu g-1), a high adsorption capacity (103.6 µmol g-1), selectivity (IF = 3.2), and fast kinetic binding (20 min) for MACs. The multiple advantages of the novel core-satellite-structured magnetic molecularly imprinted nanosorbents were confirmed, which makes us believe that the preparation method of the core-satellite MNs can be applied to other fields involving molecular imprinting technology.

Design of green coating material of combining rigid and flexible properties for the extraction of aminoglycosides residues.

Bio-based and low-cost hybrid polyvinyl alcohol (PVA) and gelatin (Gel) hydrophilic macromolecular complex coated microspheres were prepared based on one-pot process, characterized, and applied as novel sorbent materials for the purification of trace aminoglycosides from complex matrices. PVA acts as a "rigid" component in the hybrid complex to enhance its mechanical properties, while Gel's "flexible" role is to improve the swelling properties of the hybrid complex in water. It is shown that hybrid PVA/Gel-functionalized sorbents are more efficient than the respective PVA or Gel sorbents since the presence of Gel increases the material selectivity for aminoglycosides, which is due to the specific interactions occurring between the targets and amino acid residues in the hybrid materials. Under the optimum conditions, material preparation and pretreatment processes were entirely carried out in single water system without toxic organic solvent. The detection limit (LOD) of spectinomycin, kanamycin, streptomycin and dihydrostreptomycin in honey were 0.811, 0.303, 0.168, 0.045 µg⋅kg-1 respectively. Linearity was obtained in the range of 20 to 2000 ug⋅kg-1, relative recovery yield up to 84.1-111.7% were obtained and matrix effect of all four aminoglycosides was within 100.8-107.6%. Intra-day and inter-day precision under four spiking levels (5, 200, 500 and 1000 ug⋅kg-1) were less than 10.9% (n=6) and 13.6% (n=3) respectively. In addition, the sorbents exhibited excellent reusability even after six recycles. This work demonstrates the potential of bio-based and low-cost hybrid polymer extraction platforms as promising bonded phase alternatives, in which eco-friendly and natural-based polymers can be used to improve the material selectivity and are conducive to the realization of "green chemistry".

LC-APCI-MS/MS assay for quantitation of ethyl esters of eicosapentaenoic acid and docosahexaenoic acid in human plasma and its application in a pharmacokinetic study.

A simple and specific LC-MS/MS method was developed and validated for the determination of ethyl ester of eicosapentaenoic acid (EPAEE) and ethyl ester of docosahexaenoic acid (DHAEE). After deproteinized with acetonitrile, the plasma samples were separated on a C18 column using a gradient elution system consisted of methanol and 1.0 mM ammonium acetate in water. The detection used an atmospheric-pressure chemical ionization ion source in positive mode with multiple reaction monitoring for the quantitation of EPAEE and DHAEE. The acceptable linearity was achieved over the concentration ranges of 1.00~1000 ng/mL for EPAEE and 2.50~2500 ng/mL for DHAEE. The method was successfully applied to a pharmacokinetic study of EPAEE and DHAEE in healthy Chinese volunteers after the oral administration of 4 g omega-3-acid ethyl esters 90 soft capsule. The pharmacokinetic profiles of EPAEE and DHAEE were observed for the first time in Chinese volunteers, which reached a maximum concentration of 499 ± 243 ng/mL and 1596 ± 476 ng/mL for EPAEE and DHAEE, respectively. The areas under the plasma concentration-time curve were 1290 ± 765 ng/mL·h for EPAEE and 4369 ± 1680 ng/mL·h for DHAEE, respectively.

Method development and validation for simultaneous determination of ebastine and its active metabolite carebastine in human plasma by liquid chromatography-tandem mass spectrometry and its application to a clinical pharmacokinetic study in healthy Chinese volunteers.

A simple LC-tandem mass spectrometry (MS/MS) method to determine ebastine and carebastine (active metabolite) in human plasma was developed and validated. Analytes and internal standards were precipitated by protein precipitation and separated on Synergi Hydro-RP 80A column (4 µm, 50 mm × 2.0 mm; Phenomenex) by gradient elution with mobile phase A comprising 0.1% formic acid in 5 mm ammonium acetate (NH4 Ac) and B comprising 100% methanol at a flow rate 0.4 mL/min. Ions were detected in positive multiple reaction monitoring mode, and they exhibited linearity over concentration range 0.01-8.0 and 1.00-300 ng/mL for ebastine and carebastine, respectively. A clinical pharmacokinetic study was conducted in healthy Chinese volunteers under fasting and fed conditions after a single oral administration of 10 mg ebastine. The maximum plasma concentration (Cmax ), time to Cmax (Tmax ) and elimination half-life for ebastine were 0.679 ± 0.762 ng/mL, 1.67 ± 1.43 h and 7.86 ± 6.18 h, respectively, whereas these for carebastine were 143 ± 68.4 ng/mL, 5.00 ± 2.00 h and 17.4 ± 4.97 h, respectively under fasting conditions; the corresponding values under fed conditions were 4.13 ± 2.53 ng/mL, 3.18 ± 1.09 h and 21.6 ± 7.77 h for ebastine and 176 ± 68.4 ng/mL, 6.14 ± 2.0 h and 20.0 ± 4.97 h for carebastine.

An LC-MS/MS method for protein detection based on a mass barcode and dual-target recognition strategy.

A mass barcode mediated signal amplification strategy was developed and applied to the determination of protein. A new compound, N'-((2-aminopyridin-3-yl)methylene)-5-(1,2-dithiolan-3-yl)pentanehydrazide (TAPA), was synthesized from the linker and the signal barcode, and used as the bonding barcode. For the realization of signal transduction, TAPAs and the target catcher aptamers, were both modified on gold nanoparticles (AuNPs) to establish the relationship between TAPAs and the target. Owing to the fact that the amount of TAPAs was much greater than the target, the signal of the target was not only transduced to the signal of the mass barcodes, but also amplified greatly. Thrombin, an important biomarker for coagulation abnormality diseases, was selected as a model analyte. Two kinds of thrombin recognition aptamers, aptamer 29 (apt29) and aptamer 15 (apt15), were modified onto the magnetic beads (MBs) and AuNPs, respectively. The modified AuNPs were further functionalized with lots of TAPA and formed apt15-AuNPs-TAPA. MBs-apt29 and apt15-AuNPs-TAPA could both recognize the target thrombin and form the sandwich complex (MBs-apt29/thrombin/apt15-AuNPs-TAPA). After the complex was separated by an extra magnetic field, NaClO oxidant solution was added to release the signal barcodes, 2-Amino-3-pyridinecarboxaldehyde (APA), which were then collected after centrifuging and analyzed by LC-MS/MS. Under optimized conditions, the mass response intensity was proportional to thrombin concentration in the range of 0.05-10 nM, with a 0.007 nM detection limit. This method was applied to the determination of thrombin in spiked serum samples, and the average recoveries ranged from 89.6% to 110.4%, which confirmed the applicability of this method.

A new HPLC-UV derivatization approach for the determination of potential genotoxic benzyl halides in drug substances.

Benzyl halides, widely used as alkylation reagents in drug synthesis, are potential genotoxic impurities (PGTIs) required to be controlled at trace levels. However, the existing analytical methods for benzyl halides often suffer from matrix interferences or low derivatization efficiency of benzyl chlorides. In this paper, a simple derivatization HPLC-UV method was developed for the analysis of these residual trace benzyl halides in drug substances. 1-(4-Nitrophenyl) piperazine (4-NPP) was selected as a new derivatization reagent because it shifted well the benzyl halides derivatives away to the near visible range (392 nm), which could minimize the matrix interferences from the drug substances and related impurities. Meanwhile, potassium iodide (KI) was used to convert the mixed benzyl halides into benzyl iodides before derivatization. The derivatization parameters were also optimized using the design of experiments (DoE) for achieving the best reaction efficiency. The results showed that the new approach had high specificity and sensitivity, and the LOQs were 7-9 µg g-1 relative to 5 mg mL-1 antipyrine and 17.5-22.5 µg g-1 relative to 2 mg mL-1 oroxylin A. The method is a valuable alternative for the determination of residual benzyl halides in the drug substances.

A polyvinyl alcohol-coated core-shell magnetic nanoparticle for the extraction of aminoglycoside antibiotics residues from honey samples.

The authors describe magnetic nanoparticles comprising of a Fe3O4 core and a polyvinyl alcohol (PVA) coating for use in dispersive solid phase extraction (DSPE) of aminoglycoside antibiotics (AAs). The sorbent was investigated by Transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), thermo-gravimetric analysis (TGA), nitrogen adsorption-desorption isotherms and so on. The extraction conditions consisting of the proportion of ACN, pH value, buffer concentration and sorbent dosage were optimized. The nanoparticles have a large surface area (73.28 m2 g-1), a high binding capacity (11.33 µmol g-1) and a fast binding time (30 s). The Fe3O4@PVA is shown to be an effective adsorbent for the enrichment of AAs (streptomycin, dihydrostreptomycin and kanamycin) in spiked honey. The limits of detection are as low as 0.993, 0.913 and 1.23 µg kg-1 for streptomycin, dihydrostreptomycin and kanamycin, respectively. The recoveries varied from 82.9% to 100.7% at the three spiking levels tested (40, 400, 4000 µg⋅kg-1). Intra-day and inter-day assay precision were < 12.1% (n = 6) and <12.8% (n = 3) at three spiking levels. These data showed that the method could be applied to the extraction of AAs in honey samples.

Non-enzymolytic adenosine barcode-mediated dual signal amplification strategy for ultrasensitive protein detection using LC-MS/MS.

A method is described for the determination of proteins with LC-MS/MS enabled by a small molecule (adenosine) barcode and based on a double-recognition sandwich structure. The coagulation protein thrombin was chosen as the model analyte. Magnetic nanoparticles were functionalized with aptamer29 (MNP/apt29) and used to capture thrombin from the samples. MNP/apt29 forms a sandwich with functionalized gold nanoparticles modified with (a) aptamer15 acting as thrombin-recognizing element and (b) a large number of adenosine as mass barcodes. The sandwich formed (MNP/apt29-thrombin-apt15/AuNP/adenosine) can ben magnetically separated from the sample. Mass barcodes are subsequently released from the sandwiched structure for further analysis by adding 11-mercaptoundecanoic acid. Adenosine is then detected by LC-MS/MS as it reflects the level of thrombin with impressively amplified signal. Numerous adenosines introduced into the sandwich proportional to the target concentration further amplify the signal. Under optimized conditions, the response is linearly proportional to the thrombin concentration in the range of 0.02 nM to 10 nM, with a detection limit of 9 fM. The application of this method to the determination of thrombin in spiked plasma samples gave recoveries that ranged from 92.3% to 104.7%. Graphical abstract Schematic representation of a method for the determination of thrombin with LC-MS/MS. The method is based on a double-recognition sandwiched structure. With LC-MS/MS, mass barcodes (adenosine) are detected to quantify thrombin, which amplifies the detection signal impressively.

Amphotericin B-conjugated polypeptide hydrogels as a novel innovative strategy for fungal infections.

The present work is focused on the design and development of novel amphotericin B (AmB)-conjugated biocompatible and biodegradable polypeptide hydrogels to improve the antifungal activity. Using three kinds of promoting self-assembly groups (2-naphthalene acetic acid (Nap), naproxen (Npx) and dexamethasone (Dex)) and polypeptide sequence (Phe-Phe-Asp-Lys-Tyr, FFDKY), we successfully synthesized the Nap-FFDK(AmB)Y gels, Npx-FFDK(AmB)Y gels and Dex-FFDK(AmB)Y gels. The AmB-conjugated hydrogelators are highly soluble in different aqueous solutions. The cryo-transmission electron microscopy and scanning electron microscopy micrographs of hydrogels afford nanofibres with a width of 20-50 nm. Powder X-ray diffraction analyses demonstrate that the crystalline structures of the AmB and Dex are changed into amorphous structures after the formation of hydrogels. Circular dichroism spectra of the solution of blank carriers and the corresponding drug deliveries further help elucidate the molecular arrangement in gel phase, indicating the existence of turn features. The in vitro drug releases suggest that the AmB-conjugated hydrogels are suitable as drug-controlled release vehicles for hydrophobic drugs. The antifungal effect of AmB-conjugated hydrogels significantly exhibits the antifungal activity against Candida albicans. The results of the present study indicated that the AmB-conjugated hydrogels are suitable carriers for poorly water soluble drugs and for enhancement of therapeutic efficacy of antifungal drugs.

A hollow porous molecularly imprinted polymer as a sorbent for the extraction of 7 macrolide antibiotics prior to their determination by HPLC-MS/MS.

A hollow porous molecularly imprinted polymer (HPMIP) is described for use in dispersive solid phase extraction of macrolide antibiotics (MACs). The HPMIP was prepared by using spiramycin as the template, methacrylic acid as the functional monomer, and mesoporous MCM-41 (Mobile Composition of Matter No. 41; with a size of about 100 nm) as a sacrificial support. The sorbent was characterized by Fourier transform infrared spectrometry, transmission electron microscopy, nitrogen adsorption and thermo-gravimetric analysis. Several parameters affecting the extraction efficiency were optimized. The material has a large surface area (359 m2·g-1), and most recognition sites are located on the surface of the HPMIPs. This results in high binding capacity (120 µmol·g-1) and fast binding (20 min) in comparison to either MCM-41-core surface MIPs or solid MIPs. The method was applied to the extraction of the MACs azithromycin, spiramycin, tilmicosin, tylosin, clarithromycin, roxithromycin and josamycin from spiked honey. The recoveries, determined by HPLC-MS/MS, ranged from 88.0% to 117% at the three spiking levels tested (1, 5 and 20 µg·kg-1). Intra-day and inter-day assay precision at three spiking levels are <10.7% (for n = 6) and 12.6% (n = 3), respectively. The limits of detection are between 3 and 17 ng·kg-1. This indicates the superiority of the method in selective extraction of macrolides even from complex matrices. Graphical abstract Hollow porous molecularly imprinted polymers using spiramycin as the template are shown to be viable dispersive solid phase extraction adsorbents for selective enrichment of macrolide antibiotics in honey products prior to their quantitation by HPLC-MS/MS.

Sensitive and accurate detection of ALP activity using a fluorescence on-off-on switch and mass barcode signal amplification.

Alkaline phosphatase (ALP) is an important biomarker for many diseases. Therefore, the sensitive and accurate detection of ALP activity is essential for fundamental biochemical processes and clinic diagnosis. Herein, we design a fluorescent on-off-on switch for sensitive and visual detection of ALP activity. Meanwhile, mass barcode-modified quantum dots (QDs) amplified the LC-MS/MS detection signal in complex biological samples. Firstly, the QDs were modified with phosphorylated Gly-Gly-Phe-Phe-Tyr (OPO3H2) peptide (GGFFYp) and the mass barcode. The fluorescence of QDs-SS-Yp was quenched by fluorescence resonance energy transfer (FRET) between QDs-SS-Yp and dansyl chloride (DNS). ALP can hydrolyze the phosphorylated peptide to form peptide self-assemblies on the QDs-SS-Yp surfaces. The effective separation distance between the QDs-SS-Yp donor and DNS acceptor becomes larger, restricting FRET between the QDs-SS-Yp and DNS. At this point, the obvious QDs-SS-Yp fluorescence signal can be restored. However, the absence of ALP results in no peptide self-assembly on the QDs-SS-Yp surface and no obvious QDs-SS-Yp fluorescence signal was detected. Therefore, the ALP activity can be analyzed according to the degree of fluorescence restoration by the fluorescence on-off-on switch. Finally, the small tag molecules obtained by cleaving the disulfide bond of the QDs-SS-Yp as a mass barcode were used to amplify the LC-MS/MS detection signal. The proposed approach shows a good linear relationship (from 0.01 to 2.4 U L-1) and has the significant advantage of a low detection limit of 0.001 U L-1.

Simultaneous Analysis of Simple Coumarins and Furocoumarines in Cigarettes by Solid-Phase Extraction with Gas Chromatography-Mass Spectrometry.

A sensitive, high-throughput analytical method based on a GC-MS method was established for the simultaneous quantitative determination of two categories of harmful coumarins: simple coumarins (coumarin, 6-methylcoumarin, 7-methoxycoumarin, 3,4-dihydrocoumarin, and 7-ethoxy-4-methylcoumarin) and furocoumarines (psoralen, 8-methoxypsoralen, 5-methoxypsoralen, and trioxysalen). The nine analytes were extracted with ethyl acetate, purified with Oasis HLB solid-phase extraction (SPE) cartridges, and identified and quantitatively determined by GC-MS in selected-ion monitoring mode. The LODs and LOQs of these compounds were in the ranges of 12.5-21.2 and 41.6-70.0 µg/kg, respectively. Average recoveries for the nine analytes ranged from 72.7 to 86.6% at LOQ, 1.5× LOQ, and 2× LOQ spike levels, with RSDs that were typically lower than 5.1%. The SPE-GC-MS method developed in this study was initially applied to research coumarins in cigarette samples; it proved to be accurate, sensitive, convenient, and practical.

A polyvinyl alcohol-coated silica gel stationary phase for hydrophilic interaction chromatography.

Multiple layers of polyvinyl alcohol (PVA) coating are generated onto silica gel by thermal immobilization to form a stationary phase applied for hydrophilic interaction liquid chromatography (HILIC). It offers an easy way to manipulate the thickness of PVA coating and the obtained stationary phase demonstrated high efficiency and high chemical stability.

A polyvinyl alcohol-functionalized sorbent for extraction and determination of aminoglycoside antibiotics in honey.

A novel highly hydrophilic sorbent simply prepared by coating polyvinyl alcohol (PVA) onto silica gel was used for extraction and determination of aminoglycoside antibiotics (AAs). The fabricated PVA coating is aimed to effectively protect core silica gel inside and offers good hydrophilic property. In combination of hydrophilic interaction chromatography tandem mass spectrometry, the performance of the sorbent was evaluated by selecting four model AAs (dihydrostreptomycin, streptomycin, kanamycin, spectinomycin). The sorbent was found to have effective adsorption ability to hydrophilic AAs, which was superior or comparable to those of commercial ones. Good recoveries (84-112%) of model AAs spiked in honey were obtained with good precision (<12.4%) and the limit of quantitation for the proposed method was in the range of 7.8-19.4ng/mL.

[Analysis of carbapenems by hydrophilic interaction chromatography and its application].

A hydrophilic interaction chromatographic (HILIC) method has been developed for the determination of the four carbapenems in human urine and tap water. The parameters including acetonitrile amount, buffer concentration and pH on the retention behavior of the four carbapenem antibiotics on an XAmide column were explored and the possible HILIC retention mechanism was proposed. Good linearities were obtained over the mass concentration ranges of 0.1-250 mg/L for biapenem, doripenem and ertapenem with correlation coefficients (R2) = 0.999 9 and while it was 0.5-250 mg/L with R2 = 0.999 8 for meropenem. The limits of quantification (LOQs) of all carbapenems were 0.1-0.5 mg/L. The spiked recoveries were within 100.4%-111.9% (RSD < 1%) for urine samples and 79.6%-107.4% (RSD < 5%) for tap water samples all at the spiked levels of 5 mg/L and 25 mg/L. The proposed method is accurate, sensitive, simple and suitable for the determination of the four carbapenems in human urine samples and tap water samples.

Preparation of C18-functionalized Fe3O4@SiO2 core-shell magnetic nanoparticles for extraction and determination of phthalic acid esters in Chinese herb preparations.

The extraction and determination of phthalic acid esters (PAEs) residue in Chinese herbal preparations (CHP) by C18-functionalized magnetic nanoparticles (C18-FS-MNP) has been firstly performed. It was synthesized through coating Fe3O4 nanoparticles with sodium silicate, followed by freeze-drying technique and then modified with C18 groups. C18-FS-MNPs prepared via freeze-drying technique were superior to those particles prepared via common vacuum drying method in terms of dispersion and extraction recovery. C18-FS-MNPs demonstrated obvious enrichment effect for four model PAEs and 478-627-fold enrichment factors were obtained. The limit of detection was <1.89ng/mL and relative standard deviation was ranging from 3.7 to 5.8%. It was successfully applied for determination of trace PAEs residue in CHP with good recoveries.

Facile preparation of polyvinyl alcohol coated SiO2 stationary phases for high performance liquid chromatography.

A facile method to prepare a polar stationary phase for hydrophilic interaction chromatography (HILIC) was proposed by coating polyvinyl alcohol onto silica particles (PVA-Sil). A water or organic solvent-insoluble permanent PVA coating on the silica particle surface can be formed simply by dipping silica particles into a hot PVA solution and then settled from this solution, leaving a thin layer of PVA coating and frozen in a freezer. The PVA-Sil shields the silica core from solution erosion to some degree and the pH tolerance range was extended to 9.5 from 8.0 for bare silica. PVA-Sil demonstrated a good hydrophilic property for several kinds of polar compounds and ∼57000 m(-1) of plate count was achieved. This method can also be extended as a universal method to prepare various stationary phases with exchangeable functionalities by doping the desired ingredient in a PVA solution.