SPE of Tanshinones from Salvia miltiorrhiza Bunge by using Imprinted Functionalized Ionic Liquid-Modified Silica

Ionic liquid-modified silica, with functional groups based on imidazole as the cation, was obtained. A molecular imprinting technique was introduced to form the order of functional groups. The selectivity of the obtained ionic liquid-modified silica was successfully used as a special imprinted sorbent in the solid-phase extraction to isolate cryptotanshinone, tanshinone I and tanshinone IIA from Salvia miltiorrhiza Bunge. Several washing and elution solvents with different polarities were evaluated. The ionic liquid-modified silica as the sorbent exhibited a higher selectivity than blank ionic liquid-modified silica, traditional silica and C₁₈ cartridges. A quantitative analysis was conducted by liquid chromatography with a C₁₈ column and methanol/water (75:25, v/v, containing 0.5% acetic acid) as the mobile phase. A good linearity was obtained from 0.5 × 10^?4 to 0.1 mg mL^?1 (r ²  > 0.99) with relative standard deviations that were less than 4.6%.     

Solid‐phase Extraction of β‐Sitosterol from Oldenlandia diffusa Using Molecular Imprinting Polymer

The β‐sitosterol imprinted polymer was prepared for selective extraction and analysis of β‐sitosterol from Oldenlandia diffusa (O. diffusa) followed by HPLC with UV detection. The imprinted polymers show high affinity and selectivity to β‐sitosterol. Using this molecularly imprinted polymer (MIP) cartridge as solid‐phase extraction (SPE) material, the interferences could be quickly washed out and β‐sitosterol was selectively retained and enriched. HPLC analysis method was used to evaluate the characteristics of this MIP material. At the condition of mobile phase composed of MeOH/H₂O/H₃PO₄ (99/1/0.1, V/V/V, pH=6.0) and the flow rate of 1.0 mL·min^?1, a good linear relationship was demonstrated when the concentrations of β‐sitosterol were in the range of 0.50–100.0 µg·mL^?1. The recoveries ranged from 75.3% to 86.5% and the inter‐day and intra‐day relative standard deviations were less than 5%. This developed HPLC method was proved to be acceptable for extraction of β‐sitosterol from O. diffusa.     

Molecularly Imprinted Monolithic Column for Selective On-Line Extraction of Enrofloxacin and Ciprofloxacin from Urine

A simple on-line molecularly imprinted solid-phase extraction coupled with liquid chromatographic separation was developed for the simultaneous determination of enrofloxacin and its active metabolite ciprofloxacin from urine samples. The molecularly imprinted monolithic columns were synthesized in water-containing systems using norflorxacin as dummy template and methanol–water (5:1, v/v) as porogenic solvent, which reveal high affinity to enrofloxacin and ciprofloxacin in the aqueous environment. Due to the unique porous structure and flow-through channels existing in the network skeleton of the imprinted monolith, urine samples could be injected directly into the imprinted column, proteins and other biological matrix were quickly washed out and the analytes were selectively retained and enriched. Good linearity was obtained from 0.05 to 200 mg L^?1 with relative standard deviations less than 3.1%. The recoveries were higher than 87% at three different concentrations and the limit of detection of the method was 0.01 mg L^?1. Moreover, by increasing the injection volume, the sensitivity of the method could be further improved.     

Hollow Fiber/Solvent Bar Microextraction Coupled with High Performance Liquid Chromatography for Preconcentration and Determination of Tanshinones and Salvianolic Acids in Radix Salvia miltiorrhiza

Hollow fiber solvent bar microextraction coupled with high-performance liquid chromatography was developed for the preconcentration and determination of active ingredients in Radix Salvia miltiorrhiza. These ingredients include dihydrotanshinone I, cryptotanshinone, tanshinone I, tanshinone IIA, salvianolic acid B, danshensu, and protocatechuic aldehyde. To evaluate the technique, seven compounds of varying polarity were used as model analytes, and a polyvinylidene fluoride hollow fiber (1.0 cm) with octanol (2 µL) was used as microextraction bar. The extraction conditions, including the identity of the hollow fiber, organic solvent, pH, salt addition, agitation speed, extraction time, and volume, were investigated and optimized. The extraction mechanism was analyzed and verified. The two main parameters, extraction recovery and enrichment factor, were obtained. Under the most favorable conditions, the enrichment factors of the analytes were 0.7–612, the limits of detection were below 1.11 ng mL^?1, and the recoveries were between 95.4% and 101.3%. Thus, hollow fiber solvent bar microextraction is simple, rapid, and practical with a wide range of potential applications.     

Determination of Baicalin by High Performance Liquid Chromatography Coupling with Flow Injection Chemiluminescence Detection

A new method for the determination of baicalin in Scutellariae Radix extract and its preparations by high performance liquid chromatography (HPLC) coupling with flow injection chemiluminescence detection (FIA‐CL) has been developed. The method was based on the chemiluminescence reaction of potassium permanganate with baicalin in nitric acid medium; the CL intensity can be enhanced by formaldehyde. In this study, the conditions of chemiluminescence and chromatography were examined, and the schematic diagram of the HPLC‐FIA‐CL analyzer was optimized. The analytes were separated on Hypersil RP‐C18 columns (100 × 4.6 mm, I.D., 5 μm) by equality elution with 47:53 (v/v) methanol‐0.3% phosphoric acid as a mobile phase at a flow rate of 0.8 mL·min^?1 and a column temperature of 40 °C. Under the optimum condition, the CL intensity was proportional to the concentration of baicalin over the range of 4.10 × 10^?7 ? 6.15 × 10^?5mol·L^?1. The limit of detection (S/N = 3) was 2.79 × 10^?7mol·L^?1 with the relative standard deviation 2.5% (Cs = 6.15 × 10^?6 mol·L^?1, n = 5). The method has been applied to the determination of baicalin in Scutellariae Radix extract and its preparations, and satisfactory results were obtained.     

Direct purification of tanshinones from Salvia miltiorrhiza Bunge by high‐speed counter‐current chromatography without presaturation of the two‐phase solvent mixture

Tanshen, the rhizome of Salvia miltiorrhiza Bunge, is a famous Traditional Chinese Medicine for multiple therapeutic remedies. This work presents the isolation and purification of tanshinone I and tanshinone IIA from the extract of the rhizome of S. miltiorrhiza by using high‐speed counter‐current chromatography (CCC) without presaturation of the two‐phase solvent mixture. The CCC method combines the results of CCC solvent system selection and components analyses of solvent mixture by GC, and thus it is possible to add accurately each individual solvent to prepare single saturated solvent phase without presaturation. The optimum CCC solvent system is a system of hexane–ethyl acetate–ethanol–water (8:2:7:3, v/v), which has been determined by usual solvent system selection and CCC runs. As a result, over 98% pure tanshinone IIA and over 94% pure tanshinone I have been obtained by using less solvent volume. Their structures have been identified by ESI‐MS, NMR spectra.     

Determination of Cyanuric Acid in Milk Powder and Swimming Pool Water by Ion‐pair Reversed‐phase Liquid Chromatography

An ion‐pair reversed‐phase high‐performance liquid chromatographic method, using tetrabutylammonium bromide (TBAB) as ion‐pair reagent, has been developed for the analysis of cyanuric acid (CA) in milk powder and swimming pool water. It was found that the effect of the concentrations of ion‐pair reagent on the retention of cyanuric acid was different for standard solution and different real samples. The separation was carried out on a reversed‐phase C₁₈ column with 85:15 (V/V) water‐acetonitrile (ACN) containing different concentration of TBAB as mobile phase for different samples. The linear range of the calibration curve for CA was 0.1–100 mg·L^?1. The detection limits calculated at S/N=3 was 0.11 mg·L^?1 for the analysis of milk powder and 0.31 mg·L^?1 for the analysis of swimming pool water, respectively. The method was successfully applied to the analysis of CA in milk powder and swimming pool water.     

高效液相色谱法测定大鼠血浆中芳香异羟肟酸二丁基锡的含量以及它在动力学研究中的应用

[(n-Bu)2Sn[{4-ClC6H4C(O)NHO}2] (DBDCT) 是课题组自主设计合成的一种新型芳香异羟肟酸二丁基锡化合物(已获国际国内发明专利),有较高的体内和体外抗肿瘤活性,小鼠急毒实验揭示其具有较低的毒性作用,初步动物实验提示DBDCT还具有升高白细胞的功能,在肿瘤化疗治疗中将产生重要的影响。本文首次建立了HPLC法测定化合物在血浆中的动力学参数。用甲醇直接沉淀血浆蛋白,乙酰苯胺为内标, Diamonsil ODS（4.6 mm × 200 mm, 5 μm）色谱柱,甲醇:0.5%三氟乙酸水溶液（30:70,pH 3.0,v/v）为流动相,检测波长238 nm。方法在0.1～25 µg·mLl-1范围内线性关系良好(r = 0.9992),定量限和检测限分别为50 和10 ng·mL-1。该方法用来测定单次静脉注射不同剂量(2,5,12mg·kg-1) DBDCT后大鼠体内的浓度-时间曲线,并采用3p97软件对动力学参数和房室模型进行估计,结果表明DBDCT在大鼠体内的动力学符合二室模型,方法简便快速,专属性好,其动力学研究中的应用为制剂的质量控制和临床前动物合理用药以及临床研究提供了实验基础。     

Design,Synthesis, and Insecticidal Activity of 1,5‐Diphenyl‐1‐pentanone Analogues

Three series of novel 1,5‐diphenyl‐1‐pentanone derivatives were designed and synthesized. Their structures were characterized by IR, ¹H NMR techniques, and elemental analysis. The insecticidal activities of the new compounds were preliminarily evaluated. The bioassay results indicated that the compounds X11 – X30 displayed better aphicidal activity against Aphis gossypii than compounds X1 – X10 and the lead compound (E)‐1,5‐diphenyl‐1‐penten‐1‐one ( A ). The inhibitory rates of compounds X6 and X29 were 100% against Plutella xylostella (L.) at 600 mg·L^?1. Compounds X12 , X13, X19 , X24, X25 , X26 and X27 showed higher insecticidal activity against Tetranychus cinnabarinus (Boisduval) at 600 mg·L^?1 than the lead compound ( A ).     

A Simple and Sensitive Method for the Detection of Trace Pb(II) and Cd(II) based on Nafion‐coated Antimony Film Electrode

Nafion‐coated antimony film electrode (NCAFE) was prepared in situ by simultaneously plated antimony with analytes, and applied to the determination of trace Pb(II) and Cd(II) in non‐deaerated solutions by differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters, which influenced the response of the NCAFE to those metals, were thoroughly optimized and discussed. The results indicated that the sensitivity and resistance to surfactants at the NCAFE were remarkably improved with relative to the antimony film electrode (AFE). In the presence of 5 mg·L^?1 gelatin, the peak heights at the NCAFE showed 4‐fold enhancement for Pb and a 9‐fold enhancement for Cd over a bare AFE. Reproducibility of the sensor was satisfactory, and the relative standard deviations were 4.8% for 20 μg·L^?1 Pb and 3.2% for 25 μg·L^?1 Cd (n=15) with preconcentration time of 180 s. The determination limits (S/N=3) of this sensor were determined to be 0.15 μg·L^?1 for Pb and 0.30 μg·L^?1 for Cd with accumulation time of 300 s. The NCAFE was successfully applied to determining Pb(II) and Cd(II) in vegetable and water samples with satisfactory results.     

Electrochemical Sensor for Sensitive Determination of Ga(III) Ion Based on β‐Cyclodextrin Incorporated Multi‐walled Carbon Nanotubes and Imprinted Sol‐gel Composite Film

A novel sensor for detection of trace gallium ion [Ga(III)] was created by stepwise modification of a gold electrode with β‐cyclodextrin (β‐CD)/multi‐walled carbon nanotubes (MWCNTs) and an ion imprinted polymer (IIP). The sensor surface morphology was characterized by scanning electron microscopy. The electrochemical performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The sensor displayed excellent selectivity towards the target Ga(III) ion. Meanwhile, the introduced MWCNTs displayed noticeable catalytic activity, and β‐CD demonstrated significant enrichment capacity. A linear calibration curve was obtained covering the concentration range from 5.0×10^?8 to 1.0×10^?4 mol·L^?1, with a detection limit of 7.6×10^?9 mol·L^?1. The proposed sensor was successfully applied to detect Ga(III) in real urine samples.     

Removal of Lead (II) Ions by Poly(2‐octadecyl butanedioic acid): Isothermal and Kinetic Studies

Poly(2‐octadecyl‐butanedioic acid), prepared from polyanhydride PA‐18, possesses novel heavy metal adsorption characteristics. The adsorption capacity of this water insoluble polymer for lead (II) was substantially higher than other heterogeneous adsorbants and is equivalent to those obtained with homogeneous sorbants. The polymer exhibited pseudo‐second‐order kinetics and nearly complete adsorption of lead occurred in 15 min with initial lead (II) concentrations greater than 100 mg · L^?1. Adsorptive behavior was accurately predicted by the Dubinin‐Radushkevich isotherm model. The mean free energy of adsorption of lead (II) onto poly(2‐octadecyl‐butanedioic acid) was determined to be 31.6 kJ · mol^?1, suggesting an ion exchange component to the adsorption mechanism. Gibb's free energy values for this process indicate that it is spontaneous. Adsorption was relatively independent of pH in the range of 3–5, due to the utilization of the sodium carboxylate form of the chelating groups, and was not influenced by high Na⁺ concentration and moderate concentrations (up to 200 mg · L^?1) of Ca⁺². Lead (II) solutions containing 2000 mg · L^?1 Ca⁺² did reduce the adsorption of 2000 mg · L^?1 lead (II) by 28%.     

Simultaneous determination of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone in rat plasma by liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study of a standardized fraction of Salvia miltiorrhiza, PF2401-SF

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the simultaneous determination of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone, the active components of Salvia miltiorrhiza in rat plasma, was developed. After liquid-liquid extraction with tariquidar as an internal standard, tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone were eluted from an Atlantis dC18 column within 5 min with a mixture of methanol and ammonium formate (10 mm, pH 6.5; 85:15, v/v). The analytes were detected by an electrospray ionization tandem mass spectrometry in the selected reaction monitoring (SRM) mode. The standard curves were linear (r=0.999) over the concentration range of 0.25-80 ng/mL for tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone in rat plasma. The coefficients of variation and the relative errors of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone for intra- and inter-assay at four quality control (QC) concentrations were 1.1-5.1% and -4.0-6.0%, respectively. The lower limit of quantification for tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone was 0.25 ng/mL from 100 microL of plasma. This method was successfully applied to the pharmacokinetic study of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone after oral administration of PF2401-SF, the standardized fraction of Salvia miltiorrhiza enriched with tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone to male Sprague-Dawley rats.     

Determination of Uric Acid in Human Urine by Ion‐exclusion Chromatography with UV Detection Using Pure Water as Mobile Phase

A simple, rapid and accurate ion‐exclusion chromatographic method coupled with a UV detector for the determination of uric acid in human urine samples has been developed. The separation was carried out on an ion‐exclusion column using only pure water as mobile phase. The detection wavelength was 254 nm and urine sample was injected directly without any pretreatment. Furthermore, the retention behavior of uric acid on the ion‐exclusion column was researched when pure water and 1 mmol·L^?1 HCl were used as mobile phase, respectively. The stability of uric acid was also further investigated within 28 days. In this method, the linear range of the calibration curve for uric acid was 0.25–100 mg·L^?1, and the detection limit calculated at S/N=3 was 0.02 mg·L^?1. The proposed ion‐exclusion chromatographic method has been used for the determination of uric acid in human urine.     

Isolation of a Methylobacterium organophilium strain, and its application to a methanol biosensor

A methanol-utilizing strain (ME25) using methanol (MeOH) as the sole carbon source has been isolated from methane-generating pits. ME25 was identified as Methylobacterium organophilium by its physiological characteristics and 16SrDNA sequence. A MeOH biosensor was then developed by immobilizing ME25 along with sensor for dissolved oxygen (O₂). Its response is based on the depletion of O₂ following oxidation of MeOH by the bacteria. The decrease in O₂ is linearly related to the MeOH concentration in the range from 1.6 mg·L^?1 to 4800 mg·L^?1 and the detection limit for MeOH is 0.27 mg·L^?1. The response time of the biosensor is around 20 min.     

Efficient separation of tanshinones by polyvinylpyrrolidone‐stabilized graphene‐modified micellar electrokinetic chromatography

In this work, a PVP‐stabilized graphene was used in MEKC for the separation of tanshinones. Seven structurally similar tanshinones were studied, that is, tanshinone IIB, dihydrotanshinone I, tanshinone I, cryptotanshinone, 1,2‐dihydrotanshinone I, miltirone, and tanshinone IIA. To achieve optimal conditions, graphene concentration, sample solvent composition, SDS concentration, 2‐propanolconcentration, and buffer pH were investigated. At a separation voltage of 30 kV and a 41.5 cm effective length fused‐silica capillary, good resolution within 12 min was performed using 10 mM borate buffer (pH 9.3) containing 30 mM SDS, 10% v/v 2‐propanol and 6 μg/mL graphene. The method was validated in terms of linearity (r² > 0.9970), intra‐ and inter‐day precision were less than 3.56 and 4.83%, respectively. The proposed method was then successfully applied to Danshentong capsule, an herbal preparation from Salvia miltiorrhiza. Our results indicated the high separation efficiency of PVP‐stabilized graphene provided new opportunities for the analysis of complex samples.     

Determination of Parathion‐methyl in Vegetables by Fluorescent‐Labeled Molecular Imprinted Polymer

A novel sensor for the determination of parathion‐methyl based on couple grafting of functional molecular imprinted polymers (MIPs) was fabricated which is developed by anchoring the MIP layer on surfaces of silica particles embedded CdSe quantum dots by surface imprinting technology. The synthesized molecular imprinted silica nanospheres (CdSe@SiO₂@MIP) allow a high selectivity and sensitivity of parathion‐methyl via fluorescence intensity decreasing when the MIP material rebinding the parathion‐methyl molecule. Compared with the MIP fabricated in traditional method, the template of parathion‐methyl was easier to remove from the CdSe@SiO₂@MIP imprinted material. Under optimal conditions, the fluorescence intensity of parathion‐methyl at the imprinted sensor was detected by spectrofluorophotometer. The relative fluorescence intensity of CdSe@SiO₂@MIP decreased linearly with the increasing concentration of parathion‐methyl ranging from 0.013 mg·kg⁻¹ to 2.63 mg·kg⁻¹ with a detection limit (3δ) of 0.004 mg·kg⁻¹ (S/N=3), which is lower than the MIP in tradition. The imprinted film sensor was applied to detect parathion‐methyl in vegetable samples without the interference of other organophosphate pesticides and showed a prosperous application in the field of food safety.     

Quantitative determination of four diterpenoids in Radix Salviae Miltiorrhizae using LC-MS-MS

An HPLC-ESI-MS-MS method has been developed for the quantitative determination of four diterpenoids, dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA in Radix Salviae Miltiorrhizae (RSM, the root of Salvia miltiorrhiza BGE.). The diterpenoids were chromatographically separated on a C18 HPLC column, and the quantification of these diterpenoids was based on the fragments of [M+H]+ under collision-activated conditions and in Selected Reaction Monitoring (SRM) mode. The quantitative method was validated, and the mean recovery rates from fortified samples (n=5) of dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA were 95.0%, 97.2%, 93.1%, and 95.9% with variation coefficient of 6.0%, 4.3%, 3.7%, and 4.2%, respectively. The established method was successfully applied to the quality assessment of seven batches of RSM samples collected from different regions of China.     

Microspheres Sensor Based on Molecularly Imprinted Polymer Synthesized by Precipitation Polymerization

IntroductionSincethepiezoelectricbulkacousticwave (BAW)sen sorswereappliedinliquidphaseinthe 1980s ,manypapershavebeenreported .1,2 However,theapplicationofBAWsen sorsbasedonmasseffectislimitedbecauseoflackofthespecialselectivitytotheanalyte.Variousmethodshavebeenproposedtosolvethisproblem ,especiallytheapplicationofthebiomaterials .3Unfortunately ,theresultwasnotsogoodasexpected,duetotheinstinctdisadvantageofthebiomateri als ,e.g .,poorstability ,shortlifespan ,althoughpossess inghighselec…     

Preparation of l‐phenylalanine‐imprinted solid‐phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l‐phenylalanine from human urine

A novel l‐ phenylalanine molecularly imprinted solid‐phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion‐pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid‐phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l‐ phenylalanine. Under the optimized conditions of the procedure, an analytical method for l‐ phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse‐phase silica gel, the obtained molecularly imprinted polymer as an solid‐phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L^?1) for the isolation of l‐ phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion‐pair dummy template imprinting is effective for preparing selective solid‐phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples.