Rapid preconcentration method for the determination of azadirachtin-A and -B, nimbin and salannin in neem oil samples by using graphitised carbon solid phase extraction

A simple and rapid method involving solid phase extraction and liquid chromatography for the determination of azadirachtin-A and -B, nimbin and salannin at nanogram levels in neem oil samples is presented. The neem oil samples are defatted and the compounds of interest extracted by mixing the sample with hexane and passing the hexane solution through a graphitised carbon black column. After washing the column with 2 ml of hexane, azadirachtin-A and -B, nimbin and salannin are eluted with 5 ml of acetonitrile and quantified using HPLC with UV detection. The recoveries of azadirachtin-A and -B, nimbin and salannin in fortified oil samples were 97.4-104.7%. The upper limit of quantification is up to 100 micrograms ml-1 without any additional clean-up and with little interference from lipids during the analysis by HPLC. The method was successfully applied to various neem oil samples collected from different locations in India.     

涂石蜡大米傅立叶变换红外吸收光谱识别分析

针对11种未涂石蜡大米和18个涂不同量石蜡的大米样品,以石油醚提取的油脂为试样,采用傅立叶变换红外光谱仪,扫描样品的傅立叶变换红外吸收光谱,并对光谱进行预处理,提取红外特征信息,将2855与1746、1462与1163 cm-1处特征峰的面积比值为坐标,采用Origín 6.0软件作识别分类图.结果表明:特征峰的面积比值与所涂石蜡量成线性变化,大米油脂的特征峰面积比值在一定的区域分布,涂以0.05%以上石蜡的大米,其油脂特征峰面积比值与未涂石蜡米油脂的值有一定区别.     

应用立式逆流色谱和反相液相色谱制备性分离荜菝中的酰胺类化合物

A versatile countercurrent chromatography with upright type-J multilayer coil planet centrifuge,named upright countercurrent chromatography (UCCC),was applied to the isolation and purification of amides from Piper Longum L., which is widely used as an anodyne and a treatment for stomach disease in China. After saponification by KOH of the ethanol extracts solution of crud drug "Piper Longi Fructus", the fruits of Piper Longum L., the remaining solution was extracted with petroleum ether and red crude oil was obtained. Using 2.5 g red crude oil as sample, the preparative UCCC with a two-phase system composed of petroleum ether (b. p. 60 ～ 90 ℃)-ethyl acetate-tetrachloromethanemethanol-water ( 1: 1: 8: 6: 1, v/v) was successfully performed, yielding ten fractions. Then these fractions were further purified by use of reversed-phase liquid chromatography with a glass column of 500 × 10 mm I. D.packed with reversed - phase silica gel. As a result,nine amides with more than 98% purity, i.e., (2E,4E)-N-isobutyl-eicosa-2,4-dienamide, (2E, 4E, 8Z)-N-isobutyl-eicosa-2,4,8-trienamide, (2E, 4E, 8Z)-N-isobutyl-ocatadeca-2,4,8-trienamide, guineensine, pipemonaline, ( 2E, 4E )-N-isobutyl-2, 4-didecadienamide, piperine, piperanine, and piperlonguminine were isolated preparatively.     

Forensic identification of spilled biodiesel and its blends with petroleum oil based on fingerprinting information

A case study is presented for the forensic identification of several spilled biodiesels and its blends with petroleum oil using integrated forensic oil fingerprinting techniques. The integrated fingerprinting techniques combined SPE with GC/MS for obtaining individual petroleum hydrocarbons (aliphatic hydrocarbons, polyaromatic hydrocarbons and their alkylated derivatives and biomarkers), and biodiesel hydrocarbons (fatty acid methyl esters, free fatty acids, glycerol, monoacylglycerides, and free sterols). HPLC equipped with evaporative scattering laser detector was also used for identifying the compounds that conventional GC/MS could not finish. The three environmental samples (E1, E2, and E3) and one suspected source sample (S2) were dominant with vegetable oil with high acid values and low concentration of fatty acid methyl ester. The suspected source sample S2 was responsible for the three spilled samples although E1 was slightly contaminated by petroleum oil with light hydrocarbons. The suspected source sample S1 exhibited with the high content of glycerol, low content of glycerides, and high polarity, indicating its difference from the other samples. These samples may be the separated byproducts in producing biodiesel. Canola oil source is the most possible feedstock for the three environmental samples and the suspected source sample S2.     

辅助有机胺对介孔分子筛MCM-41合成及其性质的影响

采用阳离子表面活性剂十六烷基三甲基溴化铵为模板剂、硫酸铝为铝源、硅溶胶为硅源，分别使用中等链长的有机胺和正己烷作为辅助添加剂，用水热晶化法在碱性介质中合成了介孔分子筛MCM-41，通过XRD、N2吸附-脱附、SEM测试手段对得到的样品进行了对比表征分析。实验结果表明，除三乙胺外，向反应体系中加入适量的三正丙胺、三正丁基胺、三正辛胺和二异丁胺后，均能够使介孔 MCM-41的d100值和孔径增大，且具有较大的BET表面积（>1 000 m2/g）和孔容（>1 cm3/g）；加入正己烷后，也可以使得MCM-41孔径变大，但是和加入有机胺相比较，合成的样品具有较小的BET表面积（887.3 m2/g）和孔容（0.81 cm3/g）。     

Antioxidant Properties and Phenolic Composition of Sideritis Species

The antioxidant properties and phenolic composition of 27 Sideritis species were studied. Plant samples were extracted with petroleum ether using a Soxhlet apparatus. The defatted plant materials were extracted with 70% methanol. Antioxidant activities of the extracts were measured using Fe⁺² induced linoleic acid peroxidation, as indicated by thiobarbituric acid reactive substance (TBARS) production. Free radical scavenging activities were determined based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). Results were compared with standard BHT. Total phenol concentration of the extracts was estimated with Folin-Ciocalteu reagent using gallic acid as standard, and phenolic components were quantified by HPLC-DAD.     

原油非烃化合物结构与含量的馏分分离及联用色谱信息获取通用方法

用正己烷将沥青质从油样中分离,再根据类组分之间极性差别,用中性氧化铝-硅胶双层析柱将原油样其余部分分成脂肪烃、芳香烃和7个非烃馏分。各馏分回收完全。用色-质联用技术,将非烃馏分再分离并获取实验数据,为原油非烃结构和含量测定奠定有关的信息基础。不同油井样品研究和重复实验表明,方法对各种原油非烃化合物分离和信息测定有很好的重现性。     

Liquid-phase microextraction utilising plant oils as intermediate extraction medium--towards elimination of synthetic organic solvents in sample preparation

Hollow fibre based liquid-phase microextraction (LPME) using fatty oils and essential oils as the organic phase was evaluated to develop sample preparation technology eliminating the use of hazardous organic solvents. Basic drugs were extracted from different aqueous samples (0.2 to 1 mL) through approximately 15 microL of either almond oil, arachis oil, olive oil, soy-bean oil, anise oil, fennel oil, lavender oil, or peppermint oil (organic phase) immobilised within the pores of a polypropylene hollow fibre and into 20 microL of 10 mM HCOOH (acceptor phase) present inside the lumen of the hollow fibre. The extraction performance of the essential oils was comparable with the solvents normally used in LPME (dihexyl ether, n-octanol, and dodecyl acetate) in terms of extraction recovery and extraction speed. Whereas all essential oils tested were compatible with human urine, only anise oil was successful for plasma. The fatty oils provided lower recoveries than the essential oils due to higher viscosity, but all the fatty oils were compatible both with urine and plasma samples. In spite of the multi-component nature of the oils tested, they were not found to seriously contaminate the acceptor phases during extraction. In conclusion, fatty oils and essential oils may serve as alternative organic phase in LPME, eliminating the use of hazardous organic solvents.     

Poly(amic acid) and polyimide characterization using gas chromatography/mass spectrometry and particle beam liquid chromatography/mass spectrometry

A number of polymers were hydrolyzed in NH₄OH and studied using gas chromatography/ mass spectrometry (GC/MS) and particle beam liquid chromatography/mass spectrometry (particle beam LC/MS) techniques. The polymers studied in this report were as follows: BPDA-PDA, BPDA-PDA-ODA, BPDA-PDA-GFDA, PMDA-ODA, and BTDA-APB. Some of the polymer samples were hydrolyzed in both their acid and imide forms to see if any mass spectrometric differences could be detected. ln all cases, the acid and imide spectra looked the same. GC/MS was unable to determine either the amine or acid portion of these polymers via a direct injection of the sample, but when the samples were first extracted with diethyl ether and this ether extract was injected into the chromatograph, the amine portion of the polymers was readily detected. The acid portion was, again, not detected in either the sample or the ether extract. The particle beam was able to detect both the amine and acid monomeric units in the nonextracted sample.     

Development and validation of a high-sensitivity liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with chemical derivatization for the determination of ethinyl estradiol in human plasma

An ultra-sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the analysis of oral contraceptive ethinyl estradiol (EE) was developed and validated over the curve range of 2.5-500 pg/mL using 1 mL of human plasma sample. Ethinyl estradiol and the internal standard, ethinyl estradiol tetra-deuterated (EE-d4), were extracted from the plasma matrix with methyl t-butyl ether, derivatized with dansyl chloride and then back-extracted into hexane. The hexane phase was evaporated to dryness, reconstituted and injected onto the LC/MS/MS system. The chromatographic separation was achieved on a Luna C(18) column (50 x 2 mm, 5 micro m) with an isocratic mobile phase of 20:80 (v/v) water:acetonitrile with 1% formic acid. The offline derivatization procedure introduced the easily ionizable tertiary amine function group to EE. This greatly improved analyte sensitivity in electrospray ionization and enabled us to achieve the desired lower limit of quantitation at 2.5 pg/mL. This high sensitivity method can be used for therapeutic drug monitoring or supporting bio-equivalence and drug-drug interaction studies in human subjects.     

Determination of potassium in gasoline and lubricating oils by a flow-injection technique with flame atomic emission spectrometric detection

Potassium in gasoline or lubricating oil is determined by injection into petroleum spirit followed by aspiration into a flame photometer. For gasoline analysis, no prior dilution is required and the carrier also acts as the fuel supply to the flame. For oil analysis, the diluted sample is aspirated into an air-propane flame. The peak area of the potassium emission, measured with a small computer interfaced to the photometer, varies linearly with concentration over the range 0–20 mg K kg^?1 in the injected sample. The gasoline volatility influences the response to a small extent. Corrections should be applied if the sample and reference gasolines differ significantly in volatility (and density). The precision at the 10 mg kg^?1 level is better than 3%. Oxygenates or halogenated hydrocarbons do not interfere with the gasoline analysis when present at the maximum concentrations normally encountered in fuels. Sample throughputs of 40 and 100 h^?1 for gasoline and oil samples, respectively, can be attained.     

Concurrent extraction,clean‐up,and analysis of polybrominated diphenyl ethers,hexabromocyclododecane isomers,and tetrabromobisphenol A in human milk and serum

A method has been developed and validated for the concurrent extraction, clean‐up, and analysis of polybrominated diphenyl ethers (PBDEs), α‐, β‐, and γ‐hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA) in human milk and serum. Milk and serum samples were extracted using accelerated solvent extraction with acetone/hexane 1:1, v/v and liquid–liquid extraction with methyl‐tert‐butyl ether/hexane 1:1, v/v, respectively. The removal of co‐extracted biogenic materials was achieved by gel permeation chromatography followed by sulfuric acid treatment. The fractionation of the PBDEs and HBCD/TBBPA was performed using a Supelco LC‐Si SPE cartridge. The detection of the PBDEs was then performed by GC–MS and that of the HBCDs and the TBBPA was performed using UPLC–MS/MS. The pretreatment procedure was optimized, and the characteristic ions and fragmentation of the analytes were studied by MS or MS/MS. A recovery test was performed using a matrix spiking test at concentrations of 0.05–10 ng/g. The recoveries ranged from 78.6–108.8% with RSDs equal to or lower than 14.04%. The LODs were 1.8–60 pg/g. The usefulness of the developed method was tested by the analysis of real human samples, and several brominated flame retardants in different samples were detected and analyzed.     

Detection of antioxidant butylated hydroxytoluene (BHT) in Antarctic krill (Euphausia superba Dana)

In this study, butylated hydroxytoluene (BHT) was separated and prepared from Antarctic krill. BHT was separated from the volatile oil of Antarctic krill using high performance thin layer chromatography (HPTLC) with petroleum ether/ethyl acetate/hexane (4:1:0.5, v/v/v) was used as the developing solvent. The content of BHT in volatile oil was 9.20?mg/g and the content of BHT in dried Antarctic krill was 0.35?mg/g (0.070?mg/g in frozen whole Antarctic krill). The linearity, accuracy, stability, and recovery of the analysis showed that HPTLC is the most suitable method for the determination of BHT in Antarctic krill. The BHT crude sample was obtained by scraping the separated spot in the thin layer chromatography plate, which was then analyzed using high performance liquid chromatography (HPLC). The resulting sample was identified with 96.05% purity based on the HPLC analysis. The structure of BHT was determined using gas chromatography–mass spectrometry (GC–MS). The results of the HPLC and GC–MS analysis validated the HPTLC method. BHT is a widely used antioxidant in food, pharmaceuticals, and in industrial production. The exploitation and utilization of BHT in Antarctic krill is of great economic value.     

Multiresidue gas chromatographic method for determining synthetic pyrethroid pesticides in agricultural products: collaborative study

Fourteen laboratories from 6 countries and regions participated in an international collaborative study to evaluate a multiresidue gas chromatographic (GC) method for determining 8 synthetic pyrethroid pesticides in grains, fruits, and vegetables. The study design was based on Youden's matched-pairs principle for collaborative tests of analytical methods. Each laboratory analyzed 12 collaborative samples of wheat, oranges, and tomatoes as blind samples. Wheat samples were extracted with acetonitrile-water (2 + 1), while orange and tomato samples were extracted with acetone. Residues were partitioned into hexane, evaporated to dryness with a rotary evaporator, and then dissolved in hexane. The hexane extract was partitioned with acetonitrile and cleaned up on a 5% water-deactivated Florisil column with 6% ethyl ether in hexane as eluant. Residue concentrations were determined by GC with electron capture detection with splitless injection by comparison with single-point calibration standards. The appropriate standard concentration was determined by screening sample extracts before analysis. The multiresidue method was tested over the concentration range of 0.095-1.909 mg/kg depending on the 8 different of pesticides and agricultural products analyzed in the collaborative study. Statistical analysis of data from 13 laboratories showed weighted average recoveries for 8 pyrethroids in wheat, oranges, and tomatoes at 0.105-1.909, 0.095-1.909, and 0.105-0.954 mg/kg, respectively, ranging from 91.8 to 100.2%, from 88.1 to 100.6%, and from 88.2 to 101.5%, respectively. Reproducibility relative standard deviation values ranged from 6.46 to 17.74%, from 5.94 to 18.13%, and from 5.59 to 10.48%, respectively. Repeatability relative standard deviation values ranged from 6.34 to 10.84%, from 5.19 to 11.72%, and from 3.20 to 8.09%, respectively. The multiresidue GC method for determining synthetic pyrethroid pesticides in agricultural products has been adopted first action by AOAC INTERNATIONAL.     

Sample preparation and determination of ginkgo terpene trilactones in selected beverage, snack, and dietary supplement products by liquid chromatography with evaporative light-scattering detection

Ginkgo biloba leaf extract has been widely used in dietary supplements and more recently in some foods and beverages. Sample preparation procedures for determination of ginkgo terpene trilactones (including bilobalide and ginkgolides A, B, C, and J) in various sample matrixes were developed in this study. Ginkgo leaves and capsules were extracted with 5% KH2PO4 aqueous solution under sonication. Tea bags were extracted with boiling water, whereas drink samples were taken directly from the bottles. After filtration and the addition of NaCl to approximately 30% (w/v), the terpene trilactones in aqueous solutions were quantitatively extracted with ethyl acetate-tetrahydrofuran (4 + 1, v/v). Puff samples (a cereal-based fried snack item) were first defatted by using hexane or by using supercritical fluid extraction and then extracting under sonication with methanol-acetic acid (99 + 1, v/v). After evaporation of the organic phase, the terpene trilactones were redissolved in methanol and determined on a C18 reversed-phase column by liquid chromatography (LC) with evaporative light-scattering detection. The method of standard additions and gas chromatography with flame ionization detection were used for method validation. For most samples, the relative standard deviation was <10%. The identities of target compounds in ginkgo leaves and drink samples were confirmed by LC/electrospray ionization-tandem mass spectrometry.     

Determination of free and ethoxylated alkylphenols in leather with gas chromatography-mass spectrometry

An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEO(n)) and octylphenol ethoxylates (OPEO(n)) in leather samples involving the conversion of NPEO(n) and OPEO(n) into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography-mass spectrometry (GC-MS). For NPEO(n) and OPEO(n) in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC-MS. The contents of NPEO(n) and OPEO(n) were calculated by normalizing to NPEO(9) and OPEO(9), respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEO(n) and OPEO(n).     

毛细管气相色谱法测定食用油中的酚类抗氧化剂BHA、BHT、TBHQ

建立了同时测定植物油中BHA、BHT、TBHQ等3种酚类抗氧化剂的测定方法。样品中的抗氧化剂经石油醚提取、乙腈萃取后采用HP-5毛细管柱分离。样品加标回收率为82.8?.6%,相对标准偏差为1.06%~3.11%,BHA、BHT、TBHQ的最低检出量分别为5、10、5ng。该方法具有快速、灵敏度高、重现性好、前处理简单等优点。     

超临界流体萃取-硅胶柱收集联用提取蓬莪术中有效成分

采用超临界流体CO2萃取和硅胶柱收集在线联用,提取蓬莪术中的挥发油,随后分别用正己烷、乙醇和乙醚对硅胶柱进行选择性洗脱,从而使蓬莪术挥发油中有效成分莪术二酮的相对含量由原来单一萃取的10．7％提高到34．7％。     

Distribution characteristics and source tracing of petroleum hydrocarbons in the northeastern South China Sea

In recent years,oil spills caused by human activities have occurred frequently,and the resultant oil pollution has received extensive attention worldwide.In this paper,a total of 50 water samples were collected from the northeastern part of the South China Sea,and total petroleum hydrocarbons(TPHs)and n-alkane content in the samples were analyzed by gas chromatography-flame ionization detector(GC-FID) technology.The petroleum hydrocarbon characteristic indices,such as carbon predominance index(C...     

Applying Aluminum Oxide Column Chromatography Purify Extracts of Cathuranthus Roseus and Simultaneous Determination of the Indole Alkaloids by HPLC

Indole alkaloid of Cathuranthus roseus was purified by applying aluminum oxide column chromatography and an HPLC method was established to determine it. Applying aluminum oxide column chromatography produced a high purified monomer of alkaloids; the extracts of indole alkaloid were then loaded on the neutral aluminum oxide column chromatography and washed with an organic solvent (a mixture of chloroform, ether, and petroleum ether). Effect of purification was the best when the proportion of chloroform, ether, and petroleum ether was 10:10:1. To determine the content of vindoline, vinblastine, and cathuranthine exactly, the mobile phase of HPLC was water (containing 0.005 mol·L^?1 ammonium hydrogen phosphate), methanol (containing 0.67% triethylamine), and acetonitrile, the proportion of each was nonlinear.