Determination of petroleum sulfonates in crude oil by column-switching anion-exchange chromatography

A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted with the dichloromethane/methanol （60/40）. The high performance liquid chromatography （HPLC） system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.

Copper modified platinum electrode for amperometric detection of spectinomycin sulfate by anion-exchange chromatography

A La^3＋-Cu/Pt modified electrode was fabricated by electrodepositing process in CuS04 solution by adding a small amount of lanthium compound, and it was employed for direct current （DC） amperometric detection of spectinomycin by anion-exchange chromatography. Without derivatization, this method can simultaneously determine the main component and impurities in spectinomycin pharmaceutical raw material. Ease of preparation, being applied in DC detection mode and good catalytic stability confirmed the interests of this modified electrode as amperometric sensor for the determination of spectinomycin.

Study on the Separation of Co^(2+) from Zn^(2+) , Cd^(2+) by Anion-exchange Chromatography

The separation of Co 2+ from Zn 2+ , Cd 2+ by anion exchange chromatography was discussed. The chromatographic column containing anion resin 201×7 which was saturated with a solution of ammonium chloride. The effects of the eluant acidity and eluant composition on the separation were investigated. The results indicate that this anion exchange chromatography is suitable to the separation of Co 2+ from Zn 2+ , Cd 2+ , and the condition of separation is simple and convenient. When the column is saturated with NH 4Cl solution (2.0 mol/L, pH=4.0), the separation can be completed effectively. Zn 2+ and Cd 2+ can also be separa ted when different eluants are used and the pure solution with high concentration of Zn 2+ , Cd 2+ respectively can be obtained ea sily.

Synthesis and characterization of quaternized poly(phthalazinone ether sulfone ketone)for anion-exchange membrane

Chloromethylated poly（phthalazinone ether sulfone ketone） （CMPPESK） was prepared from poly（phthalazinone ether sulfone ketone） （PPESK） using chloromethyl octyl ethers （CMOE） with lower toxicity as chloromethylated regent. CMPPESK was soluble in N-methyl-2-pyrrolidone （NMP）, N,N-dimethylacetamide （DMAc） and chloroform. Quaternized poly（phthalazinone ether sulfone ketone） （QAPPESK） was prepared from CMPPESK by quaternization. QAPPESK had excellent solvent resistance, which was only partly soluble in sulfuric acid （98%） and swollen in N,N-dimethylformamide （DMF）. The vanadium redox flow battery （V-RFB） using QAPPESK anion-exchange membrane had better performance with 88.3% of overall energy efficiency.

Phosphate removal from aqueous solution by Donnan dialysis with anion-exchange membrane

The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated.The results show that phosphate could be removed from aqueous solution without supplying external high pressure or electrical potential.Under the conditions of influent phosphate of 2.0 mg/L,counterion(Cl-)concentration of 0.1 mol/L,stirring speed of 500 r/min and phase temperature of 298 K,the removal of phosphate achieves 70.0%.Decreasing counterion concentration has little influence on the removal of phosphate,but phosphate amount in anion-exchange membrane increases significantly.With the increase of stirring speed and phase temperature,the removal efficiency of phosphate greatly is improved.Existing forms of phosphate in aqueous solution affected transport of phosphate and only strong acidic pH of feed solution(pH=3.0)decreases the removal of phosphate.Transport of phosphate is also accompanied by change of pH value of feed solution.In consequence,it might be a promise potential process for phosphate advanced wastewater treatment,especially in the area where high salted nature water can be utilized.

Investigation on the Use of the Weakly Basic Polyacrylate Anion-Exchanger Amberlite IRA-68 for Sorption and Separation of Iminodiacetate Complexes of Rare Earth Elements

Based on the determined affinity series of rare earth element complexes with IMDA for the anion-exchangers, purification of macroquantities of Nd 3+ from Y 3+, Sm 3+ from Ho 3+, La 3+ from Nd 3+ and La 3+ from Pr 3+ on the weakly basic gel anion-exchanger Amberlite IRA-68 was studied. Using the presented method on 1 L of Amberlite IRA-68 in the acetate form, it is possible to obtain about 240 g Nd 2O 3 purified from Y 2O 3. Great difference in affinity of La 3+ and Nd 3+ as well as Pr 3+ complexes for this anion-exchanger in the acetate form indicates the possibility of applying this process for purification of lanthanum on the increased scale. On 1 L of Amberilte IRA-68 in the acetate form it is possible to obtain about 1125 g La 2O 3 purified from Nd 2O 3. On the basis of these results it can be assumed that unique properties of polyacrylate anion-exchangers enable their application for separation of rare earth elements.

Determination of Organic Acids in Root Exudates by High Performance Liquid Chromatography: I. Development and Assessment of Chromatographic Conditions *1

Methods for determining nine low molecular weight organic acids in root exudates were developed by using reversed phase high performance liquid chromatography with UV (ultraviolet) detection at 214 nm. The mobile phase was 18 mmol L -1 kH 2PO 4 adjusted to pH 2.25 with phosphoric acid and the flow rate was 0.3 mL min -1 . The analytical column was a reversed phase silica based C 18 column (Shim pack CLC ODS). The root exudates were collected through submerging the whole root system into aerated deionized water for 2 hours. The filtered exudate solutions were concentrated to dryness by rotary evaporation at 40 °C, dissolved in 10 mL mobile phase. The chromatographic conditions of organic acid determination were analyzed. The results showed that there was a high selectivity and sensitivity in the organic acid determination by reversed phase high performance liquid chromatography. Coefficients of variation for organic acid determination were lower than 10% except lactic acid. The recoveries were consistently between 80.1% to 108.3%. Detection limits were approximately 0.05 to 4.5 mg L -1 for organic acids except succinic acid with the detection limit of 7.0 mg L -1 . Phosphorus deficiency may contribute to the release of organic acids in soybean root exudates especially malic, lactic and citric acids.

Imidazolium group prompted alkaline anion-exchange membrane with high performance for efficient electrochemical CO_(2) conversion

Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO_(2)(eCO_(2)RR).However,few satisfactory membranes have been developed to maximize the performance of CO_(2) electrolyzers,despite its role as the core in regulating ion transport and preventing product crossover or fuel loss.Herein,we report the synthesis of alkaline anion-exchange membranes fabricated by poly(vinyl-alcohol)(PVA)and poly[(3-methyl-1-vinylimidazoliummethylsulfate)-co-(1-vinylpyrrolidone)](PQ44)for use in CO_(2) electrolysis.Owing to the unique imidazolium ring structure coupled with a three-dimensional semiinterpenetrating porous internal architecture,the PVA/PQ44-OH-membranes provide a high hydroxide conductivity(21.47 mS cm^(-1)),preferable mechanical property and thermal stability.In particular,the eCO_(2)RR used PVA/PQ44-OH^(-) as electrolyte membrane realized a charming Faradaic efficiency(88%)and partial current density(29 mA cm^(-2))at0.96 VRHE and,delivered the excellent durability over 20 h electrolysis in 0.5 mol L^(-1) KHCO_(3) electrolyte.Notably,it can even enable an ultrahigh current density beyond 100 mA cm^(-2) at^(-1).11 VRHE when the electrolyte was KOH instead,and produced the FEHCOOof 85%at a low potential of0.81 VRHE,superior to both commercial alkaline A201 and acidic Nafion117 membrane.

Quantitation of metallothionein and cadmium in metallothionein in mink livers by anion-exchange HPLC-GFAAS method

Metallothionein (MT) has a great capacity of binding heavy metals showing an interesting connection with metal toxicology, as a biochemical marker for environmental metal pollution. Anino-exchange high per formance liquid chromatography (HPLC) was used to isolate and quantitate MT in livers of minks which were contaminated with heavy metals. MT isoforms (MT-I and MT-II) were eluted at approximately 11.3 and 14.3 min respectively from a DEAE-5 PW anion-exchange column with a Tris-HCl buffer (0.01 -0.25 mol/L, pH 8.6) and detected by UV absorbance at 254 nm. The cadmium concentrations in mink liver MT elutkms were determined by graphite furnace atomic absorption spectrometry (GFAAS) . Obvious increase in liver MT-I concentration rather than liver MT-II was found when the minks were contaminated by feeding contaminated fish captured from the heavy metal-polluted river. The cadmium concentration in mink liver MT-I also increased to some extent as the contaminated level increased.

MODELLING OF MECHANICAL MECHANISM OF CHROMATOGRAPHIC SYSTEM AND THEORETICAL EQUATIONS SHOWING DYNAMICAL CHARACTERISTICS OF CHROMATOGRAPHY

A simple model of chromatographic mechanical mechanism is present, and then a scrics of theoretical chromatographic equations and fundamental Formulae are derived. These theoretical equations and formulae not only reserve thermodynamic characteristics in the current fundamental chromatographic formulae, but also introduce one or more kinetic parameter, so it is possible to make the macroscopic-control on the effect of kinetic characteristics on chromatographic system.

Gas Chromatographic Method for Identification and Quantification of Commonly Used Residual Solvents in Pharmaceuticals Products

Background: Impurities are not expected in the final pharmaceutical products. All impurities should be regulated in both drug substances and drug products in accordance with pharmacopeias and ICH guidelines. Three different types of impurities are generally available in the pharmaceutical’s product specification: organic impurities, inorganic impurities, and residual solvents. Residual solvents are organic volatile chemicals used or generated during the manufacturing of drug substances or drug products. Purpose: The aim of this study is to develop a cost-effective gas chromatographic method for the identification and quantification of some commonly used solvents—methanol, acetone, isopropyl alcohol (IPA), methylene chloride, ethyl acetate, tetrahydrofuran (THF), benzene, toluene, and pyridine—in pharmaceutical product manufacturing. This method will be able to identify and quantify the multiple solvents within a single gas chromatographic procedure. Method: A gas chromatography (GC) equipped with a headspace sampler and a flame ionization detector, and a column DB 624, 30-meter-long × 0.32-millimeter internal diameter, 1,8 μm-thick, Brand-Agilent was used to develop this method. The initial GC oven temperature was 40°C and held for 5 minutes. It was then increase to 80˚C at a rate of 2˚C per minute, followed by a further increase to 225˚C at a rate of 30˚C per minute, with a final hold at 225˚C for 10 minutes. Nitrogen was used as a carrier gas at a flow rate of 1.20 mL per minute. Dimethyl sulfoxide (DMSO) was selected as sample solvent. Results: The developed method is precise and specific. The percent RSD for the areas of six replicate injections of this gas chromatographic method was within 10.0 and the recovery result found within 80.0% to 120.0%.

Simultaneous purification of minor components in natural products using twin-column recycling chromatography with a step solvent gradient

The isolation of minor components from complex natural product matrices presents a significant challenge in the field of purification science due to their low concentrations and the presence of structurally similar compounds.This study introduces an optimized twin-column recycling chromatography method for the efficient and simultaneous purification of these elusive constituents.By introducing water at a small flowing rate between the twin columns,a step solvent gradient is created,by which the leading edge of concentration band would migrate at a slower rate than the trailing edge as it flowing from the upstream to downstream column.Hence,the band broadening is counterbalanced,resulting in an enrichment effect for those minor components in separation process.Herein,two target substances,which showed similar peak position in high performance liquid chromatography(HPLC)and did not exceed 1.8%in crude paclitaxel were selected as target compounds for separation.By using the twin-column recycling chromatography with a step solvent gradient,a successful purification was achieved in getting the two with the purity almost 100%.We suggest this method is suitable for the separation of most components in natural produces,which shows higher precision and recovery rate compared with the common lab-operated separation ways for natural products(thin-layer chromatography and prep-HPLC).

Determination of 14 Organophosphorus Pesticide Residues in Mutton by Gel Permeation Chromatography-Gas Chromatography-Mass Spectrometry(GPC-GC-MS)

[Objectives]This study was conducted to purify mutton samples by gel permeation chromatography(GPC).[Methods]Fourteen organophosphorus pesticide residues in samples were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry(GC-MS)in selective ion scanning mode(SIM).[Results]The organophosphorus pesticide standard solutions showed good linearity in the mass concentration range of 0.1-10.0μg/ml with correlation coefficients(r)not lower than 0.999,and the detection limits(S=3 N)ranged from 0.01 to 0.05 mg/kg.The average recovery values were in the range of 80.2%-99.7%,with relative standard deviations(RSDs,n=3)in the range of 1.8%-6.3%,at the addition levels of 0.5,1.0 and 2.0 mg/kg.[Conclusions]The method is simple,sensitive and accurate,and can be used for the determination of organophosphorus pesticide residues in mutton.

Comprehensive analysis of phenolic composition and antioxidant mechanisms in Gymnema sylvestre extracts using LC-MS and column chromatography

Recent studies have highlighted the potential of plant extracts as therapeutic agents for managing oxidative stress and related disorders.This study aims to elucidate the phenolic composition and antioxidant properties of Gymnema sylvestre extracts.Ethanolic reflux extraction followed by column chromatography was employed to isolate phenolic compounds.The total phenolic and flavonoid contents were quantified using the Folin–Ciocalteu and aluminum chloride colorimetric methods,respectively.Antioxidant activities were assessed by DPPH,ABTS scavenging assays and the ferric reducing antioxidant power(FRAP)assay.High-Performance Liquid Chromatography(HPLC)with a C18 column and Thermo TSQ Quantum Access Max(LC-MS)were used to determine the levels of gymnemic acid and identify other potential phenolic compounds.The analysis revealed significant antioxidant activities in the fractions.Fraction A showed the highest DPPH and ABTS scavenging activities,and Fraction C demonstrated the highest ferric reducing power.LC-MS analysis identified several phenolic compounds,indicating that these are major contributors to the antioxidant efficacy of the extract.This study provides a detailed phenolic profile and confirms the strong antioxidant potential of Gymnema sylvestre leaf extract,supporting its therapeutic use and further investigation.

Determination of Benzo[a]pyrene in Edible Oil by High Performance Liquid Chromatography-Fluorescence Detector (HPLC-FL)

In this study, an optimized high performance liquid chromatography-fluorescence detector (HPLC-FL) method for the determination of benzo[a]pyrene in edible oil was established. HPLC was performed with Thermo Fisher Scientific C18 column (250 mm×4.6 mm, 5 μm) as the chromatographic column and acetonitrile and water as the mobile phase, and the excitation wavelength and emission wavelength of fluorescence detector were 286 and 430 nm, respectively. The response was high, and the linear range was 0.5-10.0 ng/ml. The lowest limit of detection was 0.11 ng/ml, and the average recovery was 92.5%. This method is suitable for quantitative analysis of benzo[a]pyrene content in edible oil.

Study on the Chromatographic Fingerprint of Volatile Constituents from Acacia Honey

[Objective] The experiment aimed to study chromatographic fingerprint in volatile components of acacia honey and provide scientific evaluation and effective control on quality of acacia honey.[Method] Using solid-phase microextraction method to separate and detect volatile components and construct chromatographic fingerprint.[Result] The honey was preheated for 15 min in water bath at 40 ℃ and solid-phase microextraction 85 μmPA was used to extract in overhead air about 30 min,then put it into the injector and desorpted 3 min,which is in 230 ℃.The Supelco WaxTM10 30 m×0.25 mm×0.25 μm column and gradient heating program was the best method to separate volatile components from honey.83 fingerprint peaks were constructed,among which 17 common fingerprint peaks were comprised of chromatographic fingerprint of volatile components of acacia honey.[Conclusion] The chromatographic fingerprint could provide reference for quality control of acacia honey.

Simultaneous Determination of Tetramethylpyrazine and Aspirin in a New Compound Formulation by Liquid Chromatography

Aim To establish a reversed-phase liquid chromatographic (LC) method forsimultaneous determination of tetramethylpyrazine (TMP) and aspirin in a new compound formulation.Methods Chromatographic separation of the two drugs was achieved on a Diamonsil C_(18) column, usinga binary mixture of methanol-1.5% acetic acid (35:65, V/V, pH = 3.1) as mobile phase at a flow rateof 1.0 mL·min^(-1). Results Separation was completed in less than 12 min. Benzoic acid was used asthe internal standard. Recoveries at levels corresponding to 80 % to 120 % of the label claim ofthe formulation ranged from 99.6 to 100.3 % for aspirin and from 99.9 to 101.3% for TMP. The linearrange was 12.6 - 150.9 μg·mL^(-1)(r= 0.9997, n = 5) for aspirin and 25.0- 300.0 μg·mL^(-1) (r =0.9999, n = 5) for TMP. Conclusion The method developed can be used for the simultaneousdetermination of TMP and aspirin in pharmaceutical preparations.

Gel Filtration Chromatography Combined with Bradford Method for Determination of Total Residual Protein in Ferment Antibiotics

Aim A novel method has been developed for evaluation of the levels of total residual protein in antibiotics produced by fermentation using gel filtration chromatography (GFC) combined with Bradford assay based on determination of residual protein in lincomycin hydrochloride. Methods The chromatographic conditions were SuperdexTM peptide column, 0.01 mol*L-1 phosphate buffer solution as mobile phase, and flow rate of 1 mL·min-1. Five hundred microliters of lincomycin hydrochloride solution (3 g of lincomycin hydrochloride dissolved in 10 mL of mobile phase) was injected into the chromatograph and the eluted solution was collected between 6 min and 14.5 min (protein eluted from column within this period), and the residual content of total protein in the eluted solution was assayed using Bradford assay method. Results The average recovery was more than 90% for bovine serum albumin, the calibration equation for the range of 0-12 μg·mL-1 of protein was y=-0.002 4x2+0.064 2x+0.002 9, r2=0.999 9, RSD=0.1%-0.9%, and the LOD and LOQ were 3 and 10 ng·mL-1 of protein, respectively. Conclusion The novel method for determining the residual protein in ferment antibio-tics is simple, rapid, and precise.

Analysis of Sugar Components of Fermented Rice Wine by Ion Chromatography

[Objective] The aim was to analyze sugar components in fermented rice wine by ion chromatography. [Method] The optimal condition for chromatography system of sugar analysis was selected by measuring sugars in fermented rice wine with ion chromatography and pulsed amperometric detection. [Result] The optimal measurement conditions were as follows： Leacheate （Leachate）, consisting of NaOH and CH3COONa, was eluted by gradient concentrations, with column temperature at 35 ℃ and flow rate at 0.4 ml/min. In the condition, sugars in rice wine were ana- lyzed and the results showed that the method is featured by low detection limit, good repetition and high recovery rate. [Conclusion] The research establishes and determines the approaches and optimum conditions for sugar analysis in rice wine by ion chromatography and pulsed amperometric detection, providing references for advancement of research on quality improvement of fermented rice wine.

Determination of Dichlofluanid Residue in Soybean by Capillary Collumns Gas Chromatography

A method for the determination of dichlofluanid residue by Capillary Collumns Gas Chromatography was established in this study.Samples were extracted with acetone and subjected to through liquid-liquid extraction with N-hexane,and then they were cleanup with column that filled with florisil,subsequently separated by Capillary Column Gas Chromatography,and the electron capture detector （ECD） was used for detection.The detection limit of this method was 0.005 mg/kg （S/N=3）,and this method was rapid,sensitive and accurate,and was applied in the determination of dichlofluanid residue in soybean.