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101.
Magnetic nanoporous carbon as an adsorbent for the extraction of phthalate esters in environmental water and aloe juice samples 下载免费PDF全文
Li Liu Yunhui Hao Yiqian Ren Chun Wang Qiuhua Wu Zhi Wang 《Journal of separation science》2015,38(8):1411-1418
In this work, magnetic nanoporous carbon with high surface area and ordered structure was synthesized using cheap commercial silica gel as template and sucrose as the carbon source. The prepared magnetic nanoporous carbon was firstly used as an adsorbent for the extraction of phthalate esters, including diethyl phthalate, diallyl phthalate, and di‐n‐propyl‐phthalate, from lake water and aloe juice samples. Several parameters that could affect the extraction efficiency were optimized. Under the optimum conditions, the limit of detection of the method (S/N = 3) was 0.10 ng/mL for water sample and 0.20 ng/mL for aloe juice sample. The linearity was observed over the concentration range of 0.50–150.0 and 1.0–200.0 ng/mL for water and aloe juice samples, respectively. The results showed that the magnetic nanoporous carbon has a high adsorptive capability toward the target phthalate esters in water and aloe juice samples. 相似文献
102.
芜菁拮抗交通性污染物致小鼠遗传毒性效应的初步研究 总被引:1,自引:0,他引:1
钱晓薇 《浙江大学学报(理学版)》2005,32(1):89-93,98
以清洁级ICR小白鼠为实验动物,选择温州市鹿城区十里亭、火车站、南站交通岗亭为处理现场,采用小鼠骨髓嗜多染红细胞(PCE)的微核试验、小鼠精子畸形试验以及分光光度法测定小鼠肝脏过氧化氢酶(CAT)活性等实验方法,研究温州市区交通污染物对小鼠的遗传毒性及芜菁块根汁对它的拮抗效应.结果表明:经交通污染物处理的小鼠,其PCE的微核率、精子畸形率以及肝脏过氧化氢酶活性均明显高于阴性对照组;灌芜菁块根汁均可使小鼠PCE微核率、精子畸形率以及CAT活性明显下降,微核抑制率分别为62.96%、80.18%、87.36%,精子畸形抑制率分别为21.88%、45.89%、40.65%,CAT活性抑制率分别为17.27%、31.36%、37.76%.结论是交通性污染物对小鼠具有明显的遗传毒性效应;芜菁块根汁对交通性污染物引起小鼠遗传毒性效应具有显著的拮抗效应. 相似文献
103.
Zaifa Pan Lili Wang Weimin Mo Chen Wang Wei Hu Juanjuan Zhang 《Analytica chimica acta》2005,545(2):218-223
A new application of pyrolytic methylation was developed to determine benzoic acid in soft drinks by gas chromatography (GC) without using any pretreatment procedures and special pyrolyzer. With the on-line pyrolytic methylation by tetramethylammonium hydroxide (TMAH), benzoic acid was converted into its corresponding methyl ester in the injector at 280 °C. Thus, samples containing benzoic acid could be well determined by direct-injection in GC on the medium polar stationary phase column. To obtain optimum methylation conditions, important factors were investigated and then applied to the following experiments. The results were obtained as following: 280 °C as reaction temperature, 2:1 as the proportion of TMAH to benzoic acid. The storage time of mixed solution had no obvious effect on the area of benzoic acid methyl ester peak. With the p-xylene as an inter-standard, GC behaviors were investigated under these optimum conditions. The linear range achieved for benzoic acid was 1-10,000 mg/l with the correlation coefficient of 0.9985. The precision was quite high with the R.S.D. of 2.8% and the limit of detection reached 0.1 mg/l. The potential of the proposed method was assessed by applying it to the determination of benzoic acid in soft drinks. The results obtained coincided with the statement on the labels and all of the detected data were below the maximum permitted concentration of the European Union Legislation. This on-line pyrolytic methylation technique was proved to be simple to implement, sensitive and selective. 相似文献
104.
Derivatization yields of different esters (methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl) of citric, malic and isocitric acids with various acylating agents, such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride and heptafluorobutyric anhydride, were investigated. The formation of acylated malic and isocitric acid esters is rapid and quantitative whereas the acylation of citric acid esters was slow and partial in most instances. It was found that selective analytical conditions can be achieved with the O-heptafluorobutyryl n-butyl esters. The analytical applicability of the separation and determination of the malic, isocitric and citric acid contents of model solutions and of pressed lemon juice is discussed. Concentrations of 1.2 × 10?3 ?9.0 × 10?3g per 100 g of isocitric acid and 4.2 × 10?3 ?3.5 × 10?2 g per 100 g of malic acid in the presence of 9.3 × 10?1 g per 100 g of citric acid were measured with relative standard deviations of 7.5 and 4.2%, respectively. 相似文献
105.
《Magnetic resonance in chemistry : MRC》2003,41(4):237-245
A detailed analysis of the proton high‐field (600 MHz) NMR spectra of tomato juice and pulp is reported for the first time. A combination of J‐resolved, COSY, TOCSY, DOSY, 1H–13C HSQC and 1H–13C HMBC 2D sequences was used to assign each spin system and to separate the components of the complex patterns in the 1D overlapped proton spectra. To obtain resolved proton spectra of tomato pulps the high‐resolution magic angle spinning technique was used; a comparison with the liquid‐state NMR spectra of the corresponding juices was accomplished. On the basis of the assignments made, the chemical composition of tomato juices from two cultivars (Red Setter and Ciliegino) was determined. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
106.
Falta T Limbeck A Koellensperger G Hann S 《Analytical and bioanalytical chemistry》2008,390(4):1149-1157
Bioaccessibility of trace metals originating from urban particulate matter was assessed in a worst case scenario to evaluate
the uptake and thus the hazardous potential of these metals via gastric juice. Sampling was performed over a period of about
two months at the Getreidemarkt in downtown Vienna. Concentrations of the assayed trace metals (Ti, Cr, Mn, Co, Ni, Cu, Zn,
Mo, Ag, Cd, Sn, Sb, Tl and Pb) were determined in PM2.5 and PM10 samples by ICP-MS. The metal concentrations in sampled air were in the low picogram to high nanogram per cubic metre range.
The concentrations in PM2.5 samples were generally lower than those in PM10 samples. The average daily intake of these metals by inhalation for a healthy adult was estimated to be in the range of <1 ng
(Tl) to >1,000 ng (Zn). To estimate the accessibility of the inhaled and subsequently ingested metals (i.e. after lung clearance
had taken place) in the size range from 2.5- to 10-μm aerodynamic equivalent diameter, a batch-extraction with synthetic gastric
juice was performed. The data were used to calculate the bioaccessibility of the investigated trace metals. Extractable fractions
ranged from 2.10% (Ti in PM2.5) to 91.0% (Cd in PM2.5), thus yielding bioaccessible fractions (PM2.5–10) from 0.16 ng (Ag) to 178 ng (Cu). 相似文献
107.
《Journal of separation science》2018,41(7):1625-1634
The presence of pesticides in food items and beverages is a big threat to humankind, and their quantitative estimation with high precision and accuracy is always a challenge for analytical chemists. Hence, a simple and rapid method is proposed for the simultaneous determination of 30 pesticides in beverages (alcoholic and non‐alcoholic drinks). The proposed method hyphenated with triple quadrupole liquid chromatography mass spectrometry has only 2 min chromatographic runtime for the analysis of all the pesticides. All the factors affecting the extraction yield have been optimized using an experimental design; and under optimized conditions, the developed method has been validated. The detection limits for all the pesticides were in the range of 0.001–0.348 μg/L with good linearity in the concentration range of 0.01–80.0 μg/L. The coefficient of determination was in the range of (R2) ≥ 0.977 to 0.999 for all the pesticides. The method was also checked for the precision of the relative standard deviation, which was below 4.75 (intra‐day) and 8.96% (inter‐day). The recovery of the method was 92–138%. 相似文献
108.
109.
固相萃取-高效液相色谱法同时测定噻菌灵和多菌灵在浓缩菠萝汁中的残留量 总被引:3,自引:0,他引:3
建立了一种可同时测定浓缩菠萝汁中噻菌灵和多菌灵残留量的反相高效液相色谱分析法。浓缩菠萝汁样品与水按一定比例稀释后,经过调节溶液的pH值、离心、过滤,用混合相固相萃取小柱(Mixed-mode SPE)进行提取、净化,并用配有二极管阵列检测器(DAD)的液相色谱仪检测,外标法定量。使用噻菌灵和多菌灵对照品进行添加回收率测定,结果显示,本方法对噻菌灵的检出限为0.020 mg/kg,回收率为75.7%~93.3%;对多菌灵的检出限为0.020 mg/kg,回收率为80.8%~99.2%;测定的相对标准偏差均不大于5.7%。本方法简单、快速、准确,能满足常规噻菌灵和多菌灵残留量检测的需要。 相似文献
110.
This paper addresses the problem of extrapolating the technique used for filtration enhancement by superimposing pressure and flow pulsations to a pilot model of an actual production unit equipped with 14 Carbosep mineral membranes. The experimental results obtained with raw apple juice show that the maximum permeate flux enhancement is obtained at a frequency of 1 Hz and a pulsed volume of 200 ml which is significantly less than the internal volume of the membranes. The flux enhancement is a linear function of the ratio of pulsatile to steady flow and can reach up to 140% when the circuit settings are unchanged. However, when the time-averaged mean transmembrane pressure is conserved the flux enhancement is much smaller and barely exceeds 25%. 相似文献