高钛钛铁中氮的滴定法测定

利用经典的滴定法,用0.005mol·L~(-1)H_2SO_4溶液吸收在强碱性条件下,用水蒸气蒸馏出的氨,并以0.01mol·L~(-1)NaOH标准溶液返滴定过量的H_2SO_4,测定样品中氮的含量,研究了测定的最佳条件,拟定了高钛钛铁中氮的测定方法,样品的加标回收率为94%～97%,方法用于测定高钛钛铁中的氮,测定下限可至0.04%,RSD<3.5%(n=5),且稳定性好,结果满意.     

High performance liquid chromatography - Quantitative nuclear magnetic resonance - High performance liquid chromatography for purity measurement of human insulin

Quantitative Nuclear Magnetic Resonance (qNMR) is a reliable quantitative spectroscopic technique, wherein the intensity of a resonance line is directly proportional to the number of resonant nucleus, and the absolute content of the compound can be determined, this means the inorganic stabilizer in the sample would not affect the result of qNMR. High performance liquid chromatography (HPLC) is a common analytical method with a high separation capacity. This study combined HPLC and qNMR, to measure the purity of Human Insulin (HI). It started from an original HI. The first step is purifying the original HI by HPLC to get a purified HI, with organic purity of 99.78%. The second step is assessing the absolute content of the purified HI by qNMR, and got 40.25%. The third step is measuring the purity of original HI by HPLC again, using the purified HI as the reference material. This method, called HPLC-qNMR-HPLC, is more accurate (84.12%?±?1.14%) than the traditional IDMS (isotope dilution mass spectrometry) method (86.6%?±?3.4%). This study expanded the application of qNMR to proteins with molecular weight of about 5800, and showed that this method can be widely used in measuring the purity of macromolecular proteins.     

An improved method of simultaneous determination of lutein and zeaxanthin in food

Based on an official standard method of lutein analysis, an improved high performance liquid chromatography (HPLC) method for simultaneously detecting lutein and zeaxanthin was developed as focusing on the sample preparation protocol. The optimal pretreatment conditions included a saponification in a water bath for 15?min at a constant temperature of 50?°C, using a 10?mL 60% (w/v) potassium hydroxide solution, followed by extraction using 100?mL mixture of n-hexane, ethyl ether and cyclohexane (40: 40: 20, v/v/v). A mixture of dichloromethane, acetonitrile and methanol (20: 30: 50, v/v/v) was validated to elute lutein and zeaxanthin on a C₃₀ column (4.6?×?250?mm, 5?µm). The resolution between lutein and zeaxanthin is ≥2.5. A millet sample was used for methodological verification and the results showed that the linear relations for lutein and zeaxanthin were good in ranges of 0.23–9.37?μg/mL and 0.30–12.02?μg/mL, respectively. The relative standard deviations of lutein and zeaxanthin were 1.40% and 5.09%, respectively, and their spiked recoveries were between 86.60% and 98.75%. The lutein and zeaxanthin results from this modified HPLC method are superior to those from the Chinese official method and ultrasonic extraction method.     

LC�CMS�CMS Method for the Analysis of New Non-Imidazole Histamine H3 Receptor Antagonist 1-[3-(4-tert-Butylphenoxy)propyl]piperidine in Rat Serum��Application to Pharmacokinetic Studies

A sensitive and specific liquid chromatography electrospray ionisation-tandem mass spectrometry method for determination of new non-imidazole histamine H(3) receptor antagonist 1-[3-(4-tert-butylphenoxy)propyl]piperidine (DL76) in rat serum has been developed and validated. Chromatography was performed on a XBridge? C18 analytical column (2.1?×?30?mm, 3.5?μm, Waters, Ireland) with gradient elution using a mobile phase containing acetonitrile and water with an addition of 0.1% of formic acid. Detection was achieved by an Applied Biosystems MDS Sciex (Concord, Ontario, Canada) API 2000 triple quadrupole mass spectrometer. Electrospray ionization (ESI) was used for ion production. The limit of detection in the SRM mode was found to be 0.5?ng?mL(-1). The limit of quantification was 1?ng?mL(-1). The precision and accuracy for both intra- and inter-day determination of DL76 ranged from 1.65 to 15.09% and from 88.74 to 113.43%. The results of this analytical method validation allow to carry out pharmacokinetic studies in rats. The method was used for the pilot study of the pharmacokinetic behavior of DL76 in rats after intravenous administration.     

Quantitation of branched-chain amino acids in ascites by capillary electrophoresis with light-emitting diode-induced fluorescence detection

Branched-chain amino acids (BCAAs) are one of the important biomarkers for monitoring liver disease such as hepatitis or hepatoma. In this communication, we present the determination of the concentrations of BCAA in ascites by CE light-emitted diode-induced fluorescence (LEDIF) using 1.5% m/v poly(ethylene oxide) (average M(v) : ~8?000?000?g/mol) that was prepared in 10?mM sodium tetraborate solution (pH 9.3). Naphthalene-2,3-dicarboxaldehyde was used to derivatize 15 amino acids (AAs) to form naphthalene-2,3-dicarboxaldehyde (NDA)-AA derivatives prior to CE analysis. The separation of 15 NDA-AA derivatives was accomplished within 15?min, with RSD values of <5.8% (within-day) and 7.4% (between-days) with respect to their migration times. The limits of detection for the tested BCAAs ranged from 10.6 to 10.9?nM. We determined the concentrations of three BCAAs--leucine, isoleucine and valine--in ascites by applying a standard addition method, with recovery percentages ranging from 93.9 to 111%. The results obtained from this CE-LEDIF method is in good agreement with those by a gold standard method using an AA analyzer. We have found that the concentrations of the three BCAAs in ascites obtained from patients suffering from liver diseases were lower than those from healthy individuals. Our approach is highly efficient, sensitive, and cost-effective, which holds great potential for the diagnosis of liver diseases.     

High-precision analysis of ethanol in bioethanol by gas chromatography with flame ionization detector

This paper describes the establishment and validation of gas chromatography-flame ionization detector (GC-FID) method for the determination of ethanol amount fraction in bioethanol samples. A general view of the development and optimization of the method is presented. The main aim of this study is the calculation of validation parameters. Selectivity of the method was determined. Linearity (R ²?>?0.999) was obtained in the range from 9.0 to 3040???g of ethanol per sample (because the mass of the test sample used was around 200?mg, this corresponds to 45?C2200???g?g^?1). The method showed good recoveries (average 99.0?%), and the relative standard deviation for repeatability and intermediate precision was 4.5 and 5.5?%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 10 and 30???g?g^?1, respectively. The uncertainty budget was finally done according to the ??Guide to the Expression of Uncertainty in Measurement?? (GUM), and the relative expanded uncertainty was 4.8?% at coverage of k?=?2.     

Optimisation of an in-tube solid phase microextraction method coupled with HPLC for determination of some oestrogens in environmental liquid samples using different capillary columns

A simple on-line method for simultaneous determination of some oestrogens including oestriol (E3), norethisterone (NORE), ethynylestradiol (EE2), D-norgestrel (NORG) and bisphenol A (BPA), in environmental liquid samples was developed by coupling in-tube solid phase microextraction (in-tube SPME) to high-performance liquid chromatography with diode array (DAD) and fluorescence (FLD) detectors. Two capillary chromatographic columns (Supel-Q? and Carboxen? 1006 porous layer open tubular) were selected to develop this method. To achieve optimum extraction performance, several parameters were investigated including number of draw/eject cycles and the sample volume for each of the columns. Reproducibility was satisfactory for inter- and intra-day precision, yielding % RSDs of less than 10% and 7.6%, respectively. Limits of detection (LODs) and quantification (LOQs) for the proposed method using a DAD detector were achieved in the ranges of 0.04–0.63?ng?mL^?1 and 0.12–1.9?ng?mL^?1, depending of the capillary column used. Fluorescence detection improved these parameters for E3, BPA and EE2, obtaining LODs of 0.005–0.03?ng?mL^?1 and LOQs of 0.015–0.08?ng?mL^?1 using Supel-Q and LODs of 0.01–0.015?ng?mL^?1 and LOQs of 0.025–0.04?ng?mL^?1 using Carboxen. The proposed method was successfully applied to spiked environmental waters obtaining recoveries greater than 80%.     

络天青S—CPB—Brij35胶束增溶吸光光度法测人发中微量铜

在阳离子表面活性剂ＣＰＢ和非离子表面活性剂Ｂｒｉｊ３５存在下,ｐＨ７．５的弱碱性介质中,二价铜离子与络天青Ｓ形成灵敏度高的１：２络合物。应用吸光度法测定人发中微量铜,铜含量在０．０２～２．０ｍｇ·Ｌ＾－１遵守比耳定律,方法检出限为限为０．０１ｍｇ·Ｌ＾－１,平均回收主继１００．５％±０．２１％,ＲＳＤ为０．２１％。此法用于人发中微量铜的测定。结果满意。     

Isolation of three antibacterial naphthoquinones from Plumbago indica roots and development of a validated quantitative HPLC analytical method

Three naphthoquinones, plumbagin (1), 3,3'-biplumbagin (2) and elliptinone (3), isolated from Plumbago indica roots by antibacterial bioassay-guided isolation, were used as standard markers for quantitative determination. A reversed-phase HPLC method was established for the simultaneous determination of the naphthoquinones in P. indica root extracts. The method utilised a Phenomenex? ODS column (4.6?×?150?mm, 5?μm) at 25°C with a mixture of methanol and 5% aqueous acetic acid (80?:?20 v/v) as the mobile phase at a flow rate of 0.85?mL/min, and UV detection at 260?nm. The parameters of linearity, precision, accuracy specificity and sensitivity of the method were evaluated. The recovery of the method was 98.6-100.6% with good linearity (r (2?)≥?0.9997) for all three naphthoquinones. A high degree of sensitivity, specificity as well as repeatability and reproducibility (R.S.D. values less than 5%) were also achieved.     

Benzophenones and flavonoids from Hypericum maculatum and their antioxidant activities

The occurrence of three known benzophenones, namely annulatophenonoside, acetylannulatophenonoside and annulatophenone as well as a flavonol O-glycoside guajaverin in the aerial parts of Hypericum maculatum Crantz was established. In addition, hyperoside, isoquercitrin and miquelianin were isolated from this plant, as well. Radical scavenging and antioxidant activities of the isolated compounds were examined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) free radicals, ferric reducing antioxidant power (FRAP) assay and inhibition of lipid peroxidation in linoleic acid system by the ferric thiocyanate method. Isoquercitrin demonstrates the highest DPPH radical scavenging (96.6?±?0.3%), FRAP (23.8?±?0.2 Trolox equivalent, TE?mol?1) and antioxidant activity in linoleic acid system. Guajaverin and acetylannulatophenonoside show significantly strong ABTS radical scavenging activity (93.9?±?0.4% and 93.4?±?0.6%, respectively), which is comparable to that of ascorbic acid (96.2?±?0.4%).     

Simultaneous determination of methotrexate and metoclopramide in physiological fluids using RP-HPLC with ultra-violet detection; application in evaluation of polymeric nanoparticles

Methotrexate (MTX) is an anticancer drug while metoclopramide (MCP) is an antiemetic agent. Both the drugs are commonly coprescribed to avoid the emesis caused by anticancer drug. In this study, a novel, rapid, sensitive, and cost-effective reverse-phase high-performance liquid chromatography method was developed and validated for simultaneous determination of the methotrexate and metoclopramide in biological and pharmaceutical samples using sparfloxacin as internal standard. The analytes were separated on a Kromasil 100-5C18 RP (250?×?4.6?mm, 5?µm) column, methanol, and 0.05% trifloroacetic acid (36:64?v/v) as mobile phase with a flow rate of 1?mL/min, detection wavelength of 290?nm, and column oven temperature at 40°C. Both the analytes were extracted from physiological fluids (bovine aqueous humor, vitreous humor, and human plasma) using mixture of methanol and 10% perchloric acid (50:50 v/v). The method was linear over the concentration range of 0.025–1.0?µg/mL for methotrexate and 0.030–1.0?µg/mL for metoclopramide. The % recovery from human plasma was 98.57 and 96.74% for MTX and MCP, respectively, while from aqueous humor and vitreous humor was 95.84 and 98.51% for MTX.

The developed method was applied for in vitro release of MTX from polymeric nanoparticles and can be applied for analysis of pharmaceutical and biological samples containing both the drugs.     

An integration strategy to measure enzyme activities for detecting irreversible inhibitors with dimethoate on butyrylcholinesterase as a model

An integration strategy was investigated to measure initial rates of horse butyrylcholinesterase (BChE) at 50.0?µmol?L^?1 butyrylthiocholine (BTCh) for detecting irreversible inhibitors as pollutants in environment and foods with dimethoate as a model. In this integration strategy: (a) if BTCh consumption within 5.0?min was >60%, BChE initial rates were derived from maximal reaction rates, estimated by an improved integrated method, according to Michaelies-Menten kinetics at 47.0?µmol?L^?1 BTCh and Michaelis-Menten constant at 94.0?µmol?L^?1; (b) or else initial rates were determined by the classical initial rate method. Thus, the differences in BChE initial rates without and after dimethoate treatment indexed final dimethoate contents in reaction mixtures to treat BChE. Results supported that this integration strategy determined BChE activities with a linear range about two magnitudes and an upper limit about twice that by the classical initial rate method alone at 2.0?mmol?L^?1 BTCh. The coefficient of variation with this integration strategy was below 5%. The difference in BChE initial rates before and after dimethoate treatment was proportional to final dimethoate contents in reaction mixtures. By enzymatic analyses, the molar contents of dimethoate extracted from polluted cabbages were consistent with the summed molar contents of dimethoate and dimethoxon by gas-chromatography. Therefore, this integration strategy was effective to detect irreversible inhibitors as pollutants in environment and foods.     

Simultaneous determination of bioactive compounds in Piper nigrum L. and a species comparison study using HPLC-PDA

Piper nigrum L. is a traditional medicine widely used in India for illnesses such as constipation, diarrhoea, earache, gangrene, heart disease, hernia, hoarseness, indigestion, insect bites, insomnia, joint pain, liver problems, lung disease, oral abscesses, sunburn, tooth decay and toothaches. In this study, six bioactive compounds, namely piperine (1), pellitorine (2), guineensine (3), pipnoohine (4), trichostachine (5) and piperonal (6) were quantified in different extracts of P. nigrum L. and compared with those of P. longum L. and P. chaba Hunter. To evaluate the quality of P. nigrum, a simple, accurate and precise HPLC-PDA method was developed for the simultaneous determination of the above-mentioned six compounds. The separation was achieved by Phenomenex Luna RP C(18) column (150?×?4.6?mm, 5?μm, Phenomenex Inc, CA, USA) with a binary gradient solvent system of water-acetonitrile, at a flow rate of 1.0?mL?min(-1) and detected at 210, 232, 262 and 343?nm. All six calibration curves showed good linearity (R (2)?>?0.9966). The method was reproducible with intra- and inter-day variations of less than 2% and 5%, respectively. The results demonstrated that this method is simple, reliable and suitable for the quality control of these plants.     

A new HPLC–MS/MS method for investigating degradation kinetics of 6‴-feruloylspinosin and identifying its metabolites by rat intestinal bacterial flora in vitro

6?-Feruloylspinosin, a C-glycoside flavonoid, is the active ingredient responsible for the anxiolytic and sedative effects of Zizyphi Spinosiae Semen. However, the degradation mechanism of 6?-feruloylspinosin in vivo is largely unknown. In this study, we developed a simple and rapid method for determining the degradation of 6?-feruloylspinosinin in the bacterial culture using high-performance liquid chromatography (HPLC)–tandem mass spectrometry (MS). The precisions were less than 2.93%, and the accuracy (RE%) ranged from ?4.07 to 3.09%. The HPLC–MS/MS method was successfully applied to study the degradation kinetics of 6?-feruloylspinosin and identify its metabolic derivatives. The results indicated that the degradation kinetics and the rate constants were correlated with the concentration of sample solutions and the degradation process could be classified as apparent first-order kinetic reaction. Obviously, the degradation rate of 6?-feruloylspinosin was rather rapid as 80% of the compound could be decomposed in only 8–12?hr. Furthermore, two metabolites were identified from the serial hydrolysis of 6?-feruloylspinosin.     

Determination of azide in gastric fluid and urine by flow-injection electrospray ionization tandem mass spectrometry

A rapid method was developed to identify and quantify the azide ion (N(3)(-)) in gastric fluid and urine. N(3)(-) in diluted biological fluids was reacted with NaAuCl(4) to produce Au(N(3))(2)(-), which was extracted with octanol. Five microliters of the extract were flow-injected into an electrospray ionization tandem mass spectrometric instrument. Quantification of N(3)(-) was performed by selected reaction monitoring of the product ion Au(N)(N(3))(-) at m/z 253, which was derived from the precursor ion Au(N(3))(2)(-) at m/z 281, using 50 μL of aqueous solution within 10 min. This method was found to be linear up to 10(-5) M, to have a limit of quantification of 10(-7) M, a limit of detection of 3.0?×?10(-8) M, and a coefficient of variation of ≦10% at 10(-7) M. In the case of urine, 50 μL of urine were spiked with N(3)(-), this was diluted 10-fold and passed through 1 mL of a resin, and finally diluted to 100-fold of the original. This method was linear up to 10(-3) M, had a limit of quantification of 10(-5) M, a limit of detection of 3.0?×?10(-6) M, and coefficient of variation of ≦8.8% for an original urine concentration of 10(-5) M. The practical applicability of this method was checked by diluting 1 μL of a suspected suicide victim's gastric fluid 20,000-fold and 1 μL of the victim's urine 5,000-fold and then measuring the N(3)(-) levels. These levels were found to be (7.5?±?1.0)?×?10(-2) M and (3.2?±?0.4)?×?10(-3) M, respectively.     

Composition of fatty oils from semen ziziphi spinosae and its cardiotonic effect on isolated toad hearts

In this study, the composition of fatty oil from Semen Ziziphi Spinosae and its cardiotonic activity on the heart isolated from a toad were studied. Oil-in-water (O/W) emulsions of fatty oil were prepared by the perfusion method. The fatty oil had a positive inotropic effect on isolated rat hearts at a concentration between 5?×?10(-3) and 2?×?10(-2)?mL/10?mL, and the effect was in positive correlation with the concentration of calcium ions. In addition, this effect was inhibited by 2?mg/mL nifedipine, suggesting that the cardiotonic mechanism could be responsible for accelerating the inflow of calcium ions. Gas chromatography-mass spectrometry analysis showed that the main constituents of the fatty oil were 9-octadecenoic acid (43.32%), 9,12-octadecadienoic acid (42.57%), hexadecanoic acid (4.76%), 9-eicosenoic acid (2.95%), stearic acid (2.41%) and arachidic acid (0.81%). This preliminary study revealed that the fatty oil of Semen Ziziphi Spinosae exhibited remarkable cardiotonic activity in the tested models, and it is necessary to further reveal the effective substances of the fatty oil.     

Cloning, Sequence, and Association Analysis of Porcine OSAP Gene

Ovary-specific acidic protein (OSAP) is an important reproduction-related gene. In this study, we cloned the full-length cDNA sequence of porcine OSAP gene through the rapid amplification of cDNA ends method. The porcine OSAP gene encodes a protein of 238 amino acids which shares high homology with the OSAP of five species: rhesus monkey (72?%), human (70?%), cattle (68?%), horse (68?%), and dog (61?%). This gene is structured in four exons and three introns as revealed by computer-assisted analysis. PCR-RFLP was established to detect the GU373669:c.854A>T substitution of porcine OSAP gene mRNA and association of this mutation with litter size traits was assessed in Large White (n?=?100) and Landrace (n?=?100) pig populations. Results demonstrated that this polymorphic locus was significantly associated with the litter size of all parities in Large White sows and Landrace sows (P?<?0.05). Therefore, OSAP gene could be a useful candidate gene in selection for increasing litter size in pigs. These data serve as a foundation for further insight into this novel porcine gene.     

Isolation of Chromium(VI) from Aqueous Solution by Electromembrane Extraction

Electromembrane extraction (EME) is a powerful extraction and preconcentration technique for ionizable species. However, the ionic contents in the sample can influence the extraction efficiency and system stability due to electrolysis. In this work, the electromembrane extraction of chromium(VI) was developed using various levels of ionic samples. 2-Nitrophenyl octyl ether was the most suitable supported liquid membrane that delayed the electrolytic occurrence of air bubbles at the electrodes due to its high viscosity and high dielectric constant properties. The electromembrane extraction method was optimized using 5?mM NaCl (630?µS?cm^?1); the applied potential was 100?V and the extraction time was 15?min. The enrichment factor of 80 was obtained over a linear working range of 10.0–80.0?µg?L^?1. The method performance was tested using mineral water, drinking water, tap water, and surface water. The method recoveries based on matrix-matched calibration were 95–125% with standard deviations within 15%.     

A Simple Method for Monitoring Iodinated Casein in Feed Premixes by LC?CMS Using Iodothyronines as Markers

A simple and effective liquid chromatography?Cmass spectrometry method was devoleped for mornitoring iodinated casein (IC) in feed premixes. In this method, iodothyronines released from IC upon sample hydrolysis were used as markers. Samples were treated with Na₂S and hydrolyzed with Ba(OH)₂??H₂O followed by cleaned up using a SampliQ SPE cartridge. Chromatographic separation was achieved on a C₁₈ column with isocratic elution using water (0.1% formic acid, v/v) and acetonitrile as the mobile phase. Ion detection was performed using electrospray ionization in positive mode using selected ion monitoring at m/z 606, 652, 732 and 778. IC levels were mornitored by qualitative analysis of the iodothyronines and quantification of thyroxine. Validation data demonstrated that the method was selective and sensitive (??0.5?mg?g^?1) with acceptable accuracy (70.2?C128.2% recovery) and precison (RSD 5.5?C15.2%).     

Application of the molecularly imprinted solid-phase extraction to the organophosphate residues determination in strawberries

This study describe an analytical method employing gas chromatography (GC) using flame photometric detection that has been developed for the simultaneous determination of organophosphate pesticides (diazinon, disulfoton, parathion, chlorpyrifos and malathion) in strawberry samples. For this purpose, molecularly imprinted solid-phase extraction was applied as a sample preparation technique. The method was linear in the ranges from 0.10 to 1.00?μg?g^?1, for diazinon, disulfoton, parathion and chlorpyrifos, and 0.10 to 2.00?μg?g^?1 for malathion with r?>?0.99. The detection limits (LD) ranged from 0.02 to 0.05?μg?g^?1. Recovery studies yielded average recoveries in the range of 65.25 to 87.70?%. These results showed the potential of this technique for organophosphate residue monitoring in strawberry samples.