A modified QuEChERS-gas chromatography-mass spectrometry method for the determination of pesticide residues in Lonicera japonicae FlosEI北大核心CSCD

A modified QuEChERS-gas chromatography-mass spectrometry method using multi-walled carbon nanotubes （MWCNTs）as adsorbent was established for the determination of 72 pesticide residues in Lonicera japonicae Flos. The sample was extracted with Association of Official Agricultural Chemists （AOAC）extracting package，purified with MWCNTs-modified purification tube，analyzed with dynamic multiple reaction monitoring mode，and quantified with external standard method of matrix-matched standard curve. The 72 pesticides showed good linearities in the corresponding concentration ranges with correlation coefficients greater than 0.9936. The limits of detection were 0.001-0.178 μµg/kg，and the limits of quantitation were 0.002-0.593 μµg/kg. The average recoveries for four spiked levels ranged from 60.1% to 118.0%，with the relative standard deviations of 2.2%-17%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Determination of eugenol and isoeugenol in aquaculture water by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometryEI北大核心CSCD

An analytical method was established for the determination of eugenol and isoeugenol in aquaculture water by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry UPLC-Q-TOF-MS. Water samples were derivatized with dansyl chloride. The derivatization products were separated on a ThermoAccucore C18 column100 mm×2.1 mm2.6 μµm under gradient elution condition utilizing acetonitrile and 0.1% formic acid as mobile phases. Q-TOF-MS operating in mass data using alternating collision cell energyMSEmode with positive electrospray ionization was used for the identification of analytes. The results showed that the calibration curves for eugenol and isoeugenol were linear in the range of 0.1-20 μµg/L with the correlation coefficientsrhigher than 0.995. Their recoveries in aquaculture water were 83.2%-102% and 91.8%-104%respectivelywith relative standard deviationsRSDsless than 15%. The limits of detection were 0.02 and 0.05 μµg/L and the limits of quantitation were 0.05 and 0.1 μµg/Lrespectively. The method can be applied to the determination of eugenol and isoeugenol in real water samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Fluorometric determination of nonylphenol in water samples enriched with zirconium doped titanium dioxide nanotubes solid phase extraction

This paper developed a fluorometric method for the sensitive determination of nonylphenol in water samples by preconcentration with zirconium doped titanium dioxide nanotubes solid phase extraction.The parameters on extraction that would influence the enrichment performance such as the kind and volume of eluent,sample pH,sample flow rate,and sample volume were optimized in detail.Under the optimal conditions,the proposed method provided an excellent linear range of 1-150 mg/L and good LOD of 0.076 mg/L.The relative standard deviation(RSD,n = 6) was 2.8%.Proposed method was also used for the analysis of real water samples and the spiked recoveries were satisfied in the range of 98.7-103%.     

Determination of macrolides in livestock excreta by syringe purification coupled with liquid chromatography tandem mass spectrometryEI北大核心CSCD

A method of syringe-dispersive solid-phase extraction combined with ultrahigh performance liquid chromatography with tandem mass spectrometry for the simultanous determination of 10 macrolides in manurebased fertilizers was developed. After extraction with methanol and acetonitrile,the extracts were purified by insyringe dispersion solid-phase extraction in syringes pre-filled with 60 mg PSA and 30 mg C18. The resulted extracts were further separated by a BEH C18 column,detected by multiple reaction monitoring in electrospray positive ion mode,and quantified by matrix-matched external standard method. The results showed that the recoveries of the target compounds ranged from 70% to 110% at three spiked levels（10,30,and 50 μµg/kg）with the relative standard deviations ranged from 1.4% to 12%. The limits of detection and quantification were 0.57 1.75 and 2.77-5.40 μµg/kg,respectively. This method was suitable for the simultaneous determination of residual macrolides in organic fertilizers. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Determination of aniline in environmental water samples by alternating-current oscillopolarographic titration

A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosage of potassium bromide, the temperature and concentration of concomitant substances were investigated in detail. The experimental results indicated that this method was simple, rapid, and sensitive. The linear range was 8.367×10-4 to 2.789×10-2 mol L-1, the relative standard deviation (R.S.D.) was lower than 0.96%, and the spiked recoveries of aniline in environmental water samples were in the range of 99.4-106.9% under the optimal conditions. The results indicated that the present method could be used as an alternative method for aniline determination in realworld water samples.     

Analysis of nitrobenzene compounds in water and soil samples by graphene composite-based solid-phase microextraction coupled with gas chromatography–mass spectrometry

In this work, solid-phase microextraction coupled with gas chromatography–mass spectrometry was developed to determine trace levels of nitrobenzene compounds in water and soil samples. Graphene was chosen as the extraction material and its composite was coated on a stainless steel wire through sol–gel technique for the solid phase microextraction. The key parameters influencing the extraction efficiency were optimized. Under the optimal conditions, the linearity for the compounds was observed in the range of 0.02–15.0 mg/L for water samples, and 0.2–60.0 mg/kg for soil samples, with the correlation coefficients（r） of 0.9966–0.9987. The limits of detection of the method were 0.0025–0.005 mg/L for water samples, and 0.02–0.04 mg/kg for soil samples. The recoveries for the spiked samples were in the range of 72.0%–113.2%, and the precision, expressed as the relative standard deviations, was less than 12.1%.     

Determination of 12 additives in beverages by evaporation-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplets combined with liquid chromatographyEI北大核心CSCD

An analytical method for the simultaneous determination of 12 additives in beverages was developed using evaporation-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplets EVA-DLLME-SFOcombined with high performance liquid chromatography HPLC. The samples were extracted twice with 70%V/Vmethanol aqueous solution and extracted by EVA-DLLME-SFO method after the combination of the extractsand finally determined by HPLC. Extraction parameterssuch as types and amounts of extractantevaporant and heating agentthe concentration of saltand the extraction time were optimized. Under the optimized conditionsthere were good relationships in the ange of 0.25-50 μµg/mL with the limits of detection of 1.5 to 13.6 mg/kg and limits of quantification of 5.2 to 45.3 mg/kg. The recoveries at three spiked levels1025 and 50 mg/kgwere 76.8% to 101.2% with the relative standard deviations of 0.11% to 4.7%. The method can be used for rapid detection of 12 additives in beverages. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Determination of anions in lithium-ion batteries electrolyte by ion chromatography

A sensitive and accurate method based on ion chromatography was established for determination of five lithium salts in lithium-ion batteries electrolytes. Chromatographic analyses were carried out on an anion exchange column at flow rate of 1 m L/min. Under the optimal conditions, five target anions(BF_4~-,PF_6~-, TFSI~-, BOB~-and FSI~-) exhibited satisfactory linearity with a correlation coefficient of 0.9996. The relative standard derivations of the target anions were less than less than 0.94%(n = 7). The limits of detections were in the range of 0.068–0.29 mg/L with average spiked recoveries ranging from 96.8% to 105.1%.     

Dispersive Liquid-liquid Microextraction for Simultaneous Determination of Six Parabens in Aqueous Cosmetics

A simple and rapid sample preparation method of dispersive liquid-liquid microextraction（DLLME） was applied in the simultaneous determination of six parabens in the aqueous cosmetics. The analysis was performed on gas chromatography coupled with a flame ionization detection（GC-FID）. The mixed solution containing 30 μL of chloroform（extraction solvent） and 300 μL of tetrahydrofuran（dispersive solvent） was rapidly injected into the sample solution for the purpose of microextraction. After that, the solution mentioned above was centrifuged at 4000 r/min for 10 min, and then the organic sediment phase was detected by GC-FID. The effects of experimental parameters, such as the extraction solvent and the volume of it, and the dispersive solvent and the volume of it, on the yield of the extraction were studied in detail. Under the optimum conditions, the enrichment factors of the target analytes range from 87 to 214. Linearity ranges are 0.05-10.0μg/mL for methylparaben and 0.025--5.0 μg/mL for the other five parabens. The relative standard deviations（RSDs） are lower than 8.2%（n=6）. The proposed method was applied to the analysis of six parabens in eleven aqueous cosmetics. The recoveries of the target analytes in the spiked real samples are in the range of 81.0%-103%.     

Determination of catecholamines by ion chromatography coupled to acidic potassium permanganate chemiluminescence detection

A simple,fast,sensitive,highly selective and eco-friendly analytical method for the determination of catecholamines in human urine by ion chromatography（IC） with chemiluminescence（CL） detection was described in this paper.Using 12 mmol/L H₂SO₄ without any organic additive as eluent,three catecholamines including epinephrine（EP）,norepinephrine（NE） and dopamine（DA） were well separated on a cation-exchange column.The CL detection was based on the reaction of analytes with acidic potassium permanganate in the presence of formaldehyde as an enhancer.The absence of methanol and acetonitrile in eluent made the proposed method more sensitive and eco-friendly.Under the optimal conditions,the linear range of the proposed method was in the range of 0.02-0.5μg/mL.The limit of detection（LOD） was in the range of 0.6 and 5.1μg/L.The relative standard deviations （RSD） for 0.1μg/mL mixed standard solution were in the range of 0.8-1.9%（n = 11）.The method has been applied to the determination of catecholamines in human urine successfully.Excellent spiked recoveries were achieved for catecholamines ranged from 91.2%to 112.7%.     

Spectrophotometric Study on the Interaction of Water with Chloranilic Acid and its Analytical Application

The reaction between chloranilic acid and water in alcohol was studied spectrophotometrically. The conditions of reaction were investigated in detail. The stable purple complex with an absorption wavelength at 530 nm was produced from the reaction between chloranilic acid and water. As a method for determination of H2O, Beer‘s law was obeyed in range of 0-6.0 % or 0-8.0 % (V/V) with the detection limit of 0.13 %. The relative standard deviation (RSD) was less than 2 %. The proposed method has been applied to determination of tracea mount of water in ethanol, flour and food flavoring, respectively. The recoveries of water in samples were 97～102%.     

Determination of insulin aspart in plasma by liquid chromatography-quadrupole electrostatic field orbitrap high-resolution mass spectrometryEI北大核心CSCD

A rapid detection method for insulin aspart in human plasma was established by using liquid chromatography-quadrupole electrostatic field orbitrap high-resolution mass spectrometry. Samples were pretreated with a precipitant of methanol-acetonitrile-acetic acid solution (49:49:2, V/V/V), an Agilent Eclipse Plus C18 column (50 mm×2.1 mm, 3.5 µm) was selected, with 0.1% aqueous formic acid and 0.1% formic acid[1]acetonitrile as mobile phases for gradient elution, and mass spectrometry was performed in selected ions monitoring (SIM) scan mode. The experimental results showed that the linear relationship of insulin aspart in human plasma was good in the range of 0.1-10 µg/mL (R2=0.9938), with the limit of quantification of 0.1 µg/mL, and the limit of detection of 0.05 µg/mL. The recoveries ranged from 71.6% to 106.2%, and the relative standard deviations (RSDs) of the intra-day and inter-day were both less than 15%. The method can meet the inspection needs of actual cases. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Untargeted screening and quantitation of drug residues in bean sprouts by ul⁃tra performance liquid chromatography-quadrupole/orbitrap high resolution mass spectrometryEI北大核心CSCD

A method for the untargeted screening and quantitative analysis of drug residues in bean sprouts by ultra performance liquid chromatography-quadrupole/ orbitrap high resolution mass spectrometry （UPLC-QOrbitrap HRMS） was developed. In the process of screening, the samples were extracted by acetonitrile and the data were gathered via the full MS-ddMS2 mode. In the absence of standards, qualitative analysis was carried out according to the exact mass number of precursor ions and secondary fragment ions information combined with the database. The optimized dispersive solid-phase extraction （d-SPE） method was used to purify the samples. 9 compounds in bean sprouts were screened and quantified on the basis of the peak areas of the precursor ions. 9 compounds showed good linear relationships （R2＞0.990） in the linear concentration ranges. The limits of detection of this method were between 2.0-5.0 μg/kg. The recoveries of 9 compounds at three spiked levels of 5, 10, 50 μg/kg ranged from 80.1% to 111.1%, and the relative standard deviations were less than 15%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Determination of perfluorooctane sulfonic acid in cosmetics by high-perfor⁃ mance liquid chromatography-tandem mass spectrometryEI北大核心CSCD

A high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）method was developed for the determination of perfluorooctane sulfonic acid （PFOS）in cosmetics. The cosmetic samples were extracted with methanol by ultrasonication,and PFOS was quantified by HPLC-MS/MS. The samples were detected in negative multiple reaction monitoring（MRM）mode using an Agilent Poroshell 120 EC-C18 （100 mm× 2.1 mm,2.7 µμm）column with a gradient elution using 0.1% formic acid aqueous solution（A）-methanol（B）as the mobile phase. The results showed that the linearity of PFOS was good in the range of 1-100 µμg/L with the correlation coefficient r2 larger than 0.9998;the limits of detection and limits of quantification were 0.015 and 0.050 mg/kg,respectively. The average recoveries were 98.7%-112.5%,and the relative standard deviations （RSDs）were less than 5%. The method is suitable for the determination of PFOS in cosmetics. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Simultaneous determination of eleven amphenicols and antiviral drugs in aquatic products by ultra-high performance liquid chromatography-tandem mass spectrometry coupled with PRIME HLB solid phase extractionEI北大核心CSCD

An efficient ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established for the simultaneous determination of 11 amphenicols and antiviral drugs in aquatic products including fish, shrimp, soft-shell turtle and shellfish samples. Each sample was dispersed with 4%(w/w)sodium chloride solution, and extracted with 2%(V/V) ammonia-ethyl acetate solution. After the concentration of the extract, the residue was redissolved in 0.2%(V/V) aqueous solution of formic acid-acetonitrile (20∶80, V∶V), purified with Oasis PRIME HLB cartridge, and detected by UPLC-MS/MS. The samples were analyzed directly on the ZORBAX RRHD Eclipse Plus C18 column using 5 mmol/L ammonium formate and acetonitrile as mobile phase. The quantitative determination of the analytes was carried out under the multiple reaction monitoring mode with positive and negative electrospray ionization using internal standard method. Results showed that there were good linear relationships for all analytes in the corresponding concentration ranges, with the correlation coefficients not less than 0.996. The limits of quantification ranged from 0.2 to 2.0 µg/kg. The average spiked recoveries were between 84.6% and 110% with the relative standard deviations of 1.0% to 14%. The method, which has been used in risk monitoring, is suitable for rapid determination of amphenicols and antiviral drugs in aquatic products. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Flow-injection chemiluminescence determination of tryptophan using galangin-potassium permanganate–polyphosphoric acid system

A high sensitive flow-injection chemiluminescence （FI-CL） method for the determination of tryptophan has been developed. The method is based on the chemiluminescence reaction of galangin-potassium permanganate-tryptophan in polyphosphoric acid （PPA） media. Under the optimized conditions, tryptophan was determined in the range 0.05-10 μg/mL with the detection limit （3tr） of 5.0 × 10^-3 μg/mL. The relative standard deviation （RSD） was 1.0% for 11 replicate determinations of 1.0 μg/mL tryptophan. Three synthetic samples were determined selectively with recoveries in the range from 99.6% to 102.0% in the presence of other amino acids.     

Determination of trace inorganic anions in anionic surfactants by single-pump column-switching ion chromatography

An ion chromatography method has been proposed for the determination of three common inorganic anions(chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits(S/N = 3) were in the range of 0.10-0.68μg/L.The relative standard deviations(RSDs) of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.     

Determination of zidovudine using anion exchange chromatography with integrated pulsed amperometric detection

A rapid and practical method for direct detection of zidovudine in high performance anion exchange chromatography(HPAEC) has been developed with integrated pulsed amperometric detection(IPAD).Dionex AS 18(250 mm×2 mm) and AG 18 (50 mm x 2 mm) columns and 11 mmol/L NaOH solution were used for separation.Multi-step potential waveform parameters were optimized to maximize the signal-to-noise ratio(S/N).Utilizing an optimized waveform,the repeatability(intra-day) precision and intermediate(inter-day) precision are obtained with relative standard deviation(RSD) of 1.88,2.27,respectively.The limit of quantification(LOQ) and limit of detection(LOD) were found to be 9.70,3.0 ng/mL,respectively,with correlation coefficients of 0.9992 over concentration range 0.01-10μg/mL.The present method was successfully applied to the determination of zidovudine in human plasma.The recoveries of plasma sample spiked by 0.7μg/mL,2.7μg/mL obtained were 95.3-101.5%, with relative standard deviation(RSD) of 2.54%,2.21%,respectively.     

Sensitive determination of fenpropathrin, cyhalothrin and deltamethrin in environmental water samples using multiwalled carbon nanotubes cartridge prior to HPLC

This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes （MWCNTs） cartridge. Important parameters, such as the sample pH, eluent and its volume, sample flow rate and sample volume were investigated in detail. The linear ranges, the detection limits, and precisions （R.S.D.） were in the range of 0.1- 40 μg L^-11, 1.34.3 ng L^-1 and 2.3-2.8%, respectively. The performance of the proposed method was validated with real water samples, and the spiked recoveries were in the range of 91.7-117.8%, respectively. The experimental results demonstrated that the proposed method was an excellent alternative for the routine analysis of such pollutants in environmental samples. 2007 Qing Xiang Zhou. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex Selector

A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid （EDTA） as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu（Ⅱ）, Ni（Ⅱ）, Co（Ⅱ） and Fe（Ⅲ） with EDTA. The partial filling method （co-current mode） was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations （n=5） of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were 97%-101%. The detection limits based on a signal to noise ratio of 3 ： 1 were found in the range of 2-10 μg·L^-1.