超声波提取-气相色谱法测定土壤中21种酚类化合物

建立了超声波提取-气相色谱法同时测定土壤中21种酚类化合物的分析方法。用二氯甲烷和正己烷混合溶剂提取土壤中的酚类化合物,提取液经碱性水溶液分配净化,去除非酸性有机杂质,再酸化萃取酚类化合物,浓缩后采用气相色谱-氢火焰离子化检测器进行检测,外标法定量。以10 g土壤样品计,酚类化合物的检出限为0.01~0.06 mg/kg。实际样品添加回收试验的回收率为62.9%~111.4%,相对标准偏差为4.3%~24.0%(n=6),准确度和精密度均较好。结果表明:该法操作方便,净化效果好,可用于土壤中多种酚类化合物的测定。     

中心切割GC-MS法分析煤液化油中的酚类化合物

使用碱洗提酚法提取煤液化油中的酚类化合物,然后结合Deans Switch装置和LTM色谱柱模块,采用中心切割气相色谱(GC)-质谱(MS)法对提取的酚类化合物进行定性。采用GC建立标准曲线,对煤液化油中主要酚类化合物的质量分数进行测定,并测定了煤液化油中邻甲基苯酚、2-乙基苯酚、4-丙基苯酚和5-茚酚4种酚类化合物的加标回收率。结果表明,在煤液化油中共定性出51种酚类化合物,测定了其中的35种酚类化合物的质量分数,其量占煤液化油总量的2.54(wt)%,苯酚和烷基苯酚占35种酚类化合物的88.2(wt)%。煤液化油中4种酚类化合物的加标回收率高,重复性好。     

索氏提取-气相色谱法测定高含水率土壤中 21种酚类化合物

高含水率土壤样品与无水硫酸钠混合均匀后,以二氯甲烷-正己烷(2+1)混合液为提取剂进行索氏提取,提取液经氢氧化钠溶液净化,再经酸化后由二氯甲烷-乙酸乙酯(4+1)混合液提取,最后进行浓缩,采用气相色谱法测定浓缩液中21种酚类化合物的含量。用HP-5色谱柱(30m×0.25mm,0.25μm)分离,氢火焰离子化检测器检测。21种酚类化合物的质量浓度均在1.0～100.0mg·L~(-1)内与其对应的峰面积呈线性关系,检出限为0.01～0.07mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为71.4%～95.1%,测定值的相对标准偏差(n=6)为1.0%～11%。     

中心切割GC-MS法分析煤液化油中的酚类化合物

使用碱洗提酚法提取煤液化油中的酚类化合物,然后结合Deans Switch装置和LTM色谱柱模块,采用中心切割气相色谱(GC)-质谱(MS)法对提取的酚类化合物进行定性。采用GC建立标准曲线,对煤液化油中主要酚类化合物的质量分数进行测定,并测定了煤液化油中邻甲基苯酚、2-乙基苯酚、4-丙基苯酚和5-茚酚4种酚类化合物的加标回收率。结果表明,在煤液化油中共定性出51种酚类化合物,测定了其中的35种酚类化合物的质量分数,其量占煤液化油总量的2.54(wt)%,苯酚和烷基苯酚占35种酚类化合物的88.2(wt)%。煤液化油中4种酚类化合物的加标回收率高,重复性好。     

高效液相色谱-串联质谱法同时测定空气中10种酚类化合物的含量

提出了高效液相色谱-串联质谱法同时测定空气中苯酚、4-硝基酚、3-甲酚、2-氯酚、2,4-二甲酚、2,4-二氯酚、2,4,6-三氯酚、五氯酚、1-萘酚、2-萘酚等10种酚类化合物含量的方法。用XAD-7采样管采样,用甲醇洗脱;收集2.0 mL洗脱液,分取0.5 mL,再用水定容至1.0 mL,过0.22μm滤膜。以Kinetex C₁₈色谱柱为固定相,以不同体积比的甲醇-水的混合溶液为流动相进行梯度洗脱。分离后的酚类化合物经大气压化学电离源电离,多反应监测模式检测,外标法定量。结果表明：10种酚类化合物标准曲线的线性范围均为10～1 000μg·L^-1,检出限(3.143s)为0.2～1.7μg·m^-3;对空白样品进行3个浓度水平的加标回收试验,回收率为69.3%～102%,测定值的相对标准偏差(n=6)为1.1%～9.6%;方法用于10个实际空气样品分析,其中有3个样品检出苯酚,质量浓度为23.3～40.2μg·m^-3。     

加速溶剂提取-固相萃取-液相色谱/串联质谱法测定土壤中酚类化合物

建立了加速溶剂提取-固相萃取-液相色谱/串联质谱(ASE-SPE-LC-MS/MS)法同时测定土壤中8种酚类化合物的方法。土壤样品经正己烷-二氯甲烷提取后，在提取液中加入pH>12的强碱性水，使得酚类化合物生成对应的盐并溶于水。将弃去有机相后得到的水相调节至pH<2，经HLB固相萃取柱富集净化，LC-MS/MS检测，外标法定量。结果表明：该方法在质量浓度10～1000μg/L范围内线性良好，相关系数(R²)大于0.995，检出限为0.2～2μg/kg；在5, 20, 100μg/kg 3个加标水平下的平均回收率为60.3%～98.1%，相对标准偏差为1.2%～11%。采用该方法检测土壤样品，检出5种酚类化合物，含量范围在0.4～1185μg/kg。     

固相萃取-高效液相色谱法测定水中酚同系物

水样中7种酚同系物用固相萃取法在Oasis HLB柱上预富集,经吹氮干燥后用1 mL甲醇将包括苯酚、4-硝基酚、3-甲基酚、2-氯酚、2,4-二氯酚、2,4,6-三氯酚及五氯酚在内的7种酚同系物从柱上淋洗,所得淋出液直接进样进行高效液相色谱法测定.在所提出的最佳测定条件下,4-硝基酚质量浓度在4.0 mg·L-1以内,其余6种酚同系物质量浓度在20.0 mg·L-1以内与相应的检测信号之间呈线性关系,以10倍信噪比计算方法的测定下限,测得4-硝基酚的测定下限为0.02 mg·L-1,其余6种酚同系物为0.1 mg·L-1以下.用标准加入法测定方法的回收率,所用基体水样中未检出上述7种酚同系物,测得回收率在79.4%-103.0%之间,相应的相对标准偏差(n=7)在1.0%～6.7%之间.     

长江沿岸某化工园区土壤、底泥中酚类化合物的污染现状

建立了同时测定土壤（底泥）样品中12种酚类化合物的检测方法。采用加速溶剂萃取（ASE）与凝胶渗透色谱（GPC）协同净化进行前处理,气相色谱和质谱联用技术（GC-MS）进行定性定量分析。方法检出限为0.410~13.1 μg/kg（干重）,回收率在70.7%~122%之间,相对标准偏差（RSD）为1.2%~16%。基于上述分析方法研究了长江沿岸某化工园区土壤及长江底泥中12种酚类化合物的污染水平。17个土壤样品和7个底泥样品中除对苯二酚外的11种酚类化合物均有检出。土壤和底泥中酚类污染物总含量范围分别为10.16~30.66 mg/kg和18.00~29.83 mg/kg,平均含量分别为18.26 mg/kg和22.51 mg/kg。土壤和底泥中最主要的酚类污染物为4-硝基苯酚和4-氯-3-甲酚,其次为邻氯对苯二酚、4,6-二硝基邻甲基苯酚和2,4,6-三氯酚。该化工园区周边土壤及长江底泥中12种酚类污染物污染水平较低、环境风险较小。     

超高效液相色谱-串联质谱法测定染发剂中7种酚类化合物

提出了应用超高效液相色谱-串联质谱法同时测定染发剂中4-氨基-2-硝基苯酚、3-二乙氨基酚、2-氨基-4-氯苯酚、2-氨基-5-硝基苯酚、2-氨基-3-硝基苯酚、1,7-二羟基萘酚和2,3-二羟基萘酚等7种酚类化合物的方法。采用甲醇萃取染发剂中酚类成分,经WatersAcquityUPLCTMBEHC18色谱柱分离,外标法定量,多反应监测模式采集质谱数据。7种酚类化合物的检出限(3S/N)均低于50.0μg.L-1。在10,20,50μg.g-1三个添加水平下,7种酚类化合物的回收率在68.8%～112.5%之间,相对标准偏差(n=6)在1.58%～12.61%之间。     

高效液相色谱法同时测定纺织品中10种酚类化合物

建立了高效液相色谱法同时测定纺织品中五氯苯酚、2,3,4,5-四氯苯酚、2,3,4,6-四氯苯酚、2,3,5,6-四氯苯酚、2,4,5-三氯苯酚、2,4,6-三氯苯酚、邻苯基苯酚、间羟基联苯、2-萘酚、对硝基苯酚10种酚类化合物的检测方法。纺织品中的酚类化合物经甲醇超声提取、浓缩后,以ZORBAX SB-C18柱(4.6 mm×150 mm,5μm)为分析柱,乙腈和0.01 mol/L磷酸溶液为流动相梯度洗脱,采用二极管阵列检测器,在220 nm和310 nm波长下进行高效液相色谱检测,紫外光谱库确证,外标法定量。10种酚类化合物在0.3～37 mg/L浓度范围内与其峰面积呈良好的线性关系,相关系数为0.999 1～0.999 5;以不低于3倍的信噪比计算10种酚类化合物的检出限(LOD)为0.003 0～0.041 1 mg/kg;定量下限(LOQ,S/N≥10)为0.010 0～0.1370 mg/kg。棉、麻、毛3种纺织品基质在3个不同加标水平的回收率为81%～105%,相对标准偏差(RSDs)为1.7%～8.5%。该方法能同时完成10种酚类化合物的确证和分析,可用于纺织品中酚类化合物残留的检测分析。     

Comparison of extraction techniques for the isolation of explosives and their degradation products from soil

A comparison of four extraction techniques used for the isolation of 14 explosive compounds (Method 8330-Explosives) from spiked soil samples is described. Soxhlet warm extraction (SWE), pressurized solvent extraction (PSE), microwave assisted extraction (MAE) and supercritical fluid extraction (SFE) were included. The effects of basic extraction conditions – i.e. type of extraction solvent, temperature, pressure, and extraction time – were investigated. The best extraction recovery of the monitored compounds from spiked soil was obtained using pressurized solvent extraction. Recoveries of explosives using the PSE technique were in the range from 65 to 112%. Extraction recoveries by Soxhlet warm extraction and supercritical fluid extraction reached 65–99% and 52–75%, respectively. The lowest extraction recoveries (28–65%) were obtained using microwave assisted extraction. A very low extraction recovery for tetryl was observed in all cases but the best results were achieved by pressurized solvent extraction (58%).     

Determination of polar nitroaromatic compounds in soils and the impact of the soil properties on the extraction results

An HPLC compatible method based on pressurized solvent extraction (PSE) for the determination of fifteen polar nitroaromatic compounds (pNC) in soil is described. The PSE method was compared with ultrasonic activated extraction. Thereby, analyzing sandy, clayey, and organic rich spiked soil samples, the influence of soil texture on the extraction yield was examined. Considering different soil properties recovery rates of investigated pNC and limiting extraction parameters were determined for both techniques. The extraction recovery of some pNC was found to show dependence on the clay content and correlation with the organic carbon amount of the soil.     

Analysis of chlorophenols,bisphenol-A, 4-tert-octylphenol and 4-nonylphenols in soil by means of ultrasonic solvent extraction and stir bar sorptive extraction with in situ derivatisation

A novel method based on ultrasonic solvent extraction and stir bar sorptive extraction for the analysis of phenolic organic pollutants including chlorophenols, bisphenol-A, 4-tert-octylphenol and 4-nonylphenol in soil samples was developed. The different parameters that affect both the extraction of analytes from the soil samples, such as solvent selection, extraction time, and the partitioning from the solvent/water mix to poly(dimethylsiloxane) (PDMS) were studied. The final selected conditions consisted of the extraction of 1 g of soil with 15 mL methanol by sonication for 30 min. The methanol extract was mixed with 85 mL of Milli-Q water and extracted by means of stir bar sorptive extraction with in situ derivatisation. The stir bars were analyzed by thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). The effects of the matrix on the recovery of the various pollutants under the developed method were studied using two soils with very different physicochemical properties. Method sensitivity, linearity, repeatability, and reproducibility were also studied. Validation and accuracy of the method were conducted by analyzing two commercial certified reference materials and by comparing the analysis of real samples with the proposed method and a classical method using pressurized solvent extraction (PSE)–GC–MS. The main advantage of this method is a substantial solvent reduction. For the extraction of only 1 g of solid sample allowing limits of detection ranging from 0.2 to 1.7 μg kg⁻¹ dw. Repeatability and reproducibility variation were lower than 20% for all investigated compounds. Results of the certified reference materials and the real samples verify the high accuracy of this method.     

An ultrasound-based technique for the analytical extraction of phenolic compounds in red algae

Phenolic compounds are bioactive compounds that are also naturally found in red algae. To determine the level of these compounds in the red algae, spectroscopic or chromatographic determination was applied over the liquid extracts. Therefore, a prior extraction method is needed. The presented study aimed to develop the analytical ultrasound-assisted extraction (UAE) method to extract phenolic compounds from red algae. A Box–Behnken design (BBD) based on five factors included solvent composition (50–90% ethanol in water), extraction temperature (10–60 °C), ultrasonic power (20–100%), pulse duty-cycle (0.2–1.0 s^?1), and solvent-to-sample ratio (10:1 to 30:1) was used to evaluate the effects of the studied factors. Subsequently, response surface methodology (RSM) was performed to define the optimum extraction condition to recover phenolic compounds from the alga matrices. The UAE condition suggested by RSM was: ultrasonic power 100%, pulse duty-cycle 1 s^?1, temperature 52.5 °C, extraction solvent 50% ethanol in water, and solvent-to-sample ratio 30:1. Kinetic studies confirmed 10 min to provide comparable recovery (p > 0.05) than any longer extraction time. The acceptable values validated the developed method for repeatability (CV, 4.8%) and intermediate precision (CV, 5.7%). In addition, the accuracy of the method suggested a complete recovery for two extraction cycles. Furthermore, the method has successfully been applied for a number of samples covering three different red algae species. Fingerprints of each sample based on phenolic composition and levels characterize the type and origin of different red algae species.     

Polypyrrole–montmorillonite nanocomposite as sorbent for solid‐phase microextraction of phenolic compounds in water

A fiber‐coated polypyrrole–montmorillonite nanocomposite was prepared for solid‐phase microextraction. The fiber coating can be prepared easily; it is mechanically stable and exhibits relatively high thermal stability. The prepared fiber was evaluated for the extraction of some phenolic compounds from aqueous sample solutions by gas chromatography–mass spectrometry. The effects of the extraction and desorption parameters including extraction time, extraction temperature, stirring rate, ionic strength, pH and desorption temperature and time have been studied. At optimum conditions, the repeatability for one fiber (n = 5), expressed as % relative standard deviation was between 6.5 and 7.8% for the phenolic compounds. The detection limits for the studied phenolic compounds were between 0.05–1.3 ng/mL. The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost, thermal stability of the fibers, and high relative recovery in comparison to conventional methods of analysis.     

Selective pressurized liquid extraction for multi-residue analysis of organochlorine pesticides in soil

A selective pressurized liquid extraction (SPLE) procedure capable of performing simultaneous extraction and clean-up has been demonstrated for multi-residue analysis of organochlorine pesticides (OCPs) in soil. The final method was performed at 100 degrees C for 3 x 10 min using acetone/n-heptane (1:1, v/v). Florisil was placed inside the extraction cell downstream the sample to remove interfering compounds. Extraction of two soil samples by SPLE gave a recovery which was over 80% for beta-endosulfan, endosulfan sulfate, p,p'-DDT and p,p'-DDE compared to PLE with off-line clean-up. The same trend was observed when applying the SPLE method to a certified reference soil sample (CRM 811-050) containing 13 OCPs, where the SPLE method gave 80-90% recovery vis-à-vis the PLE method with off-line clean-up. Feasibility of the SPLE method was further demonstrated by applying it to five real soil samples collected in Ethiopia.     

碘化钾―甲基异丁基甲酮萃取―火焰原子吸收法测定土壤中的痕量铅

土壤样品经微波消解,在优化的条件下,用碘化钾―甲基异丁基甲酮萃取,采用火焰原子吸收光谱法测定其中的铅。结果表明,在盐酸质量分数为1%～2%,萃取时间为2 min,平衡时间为15 min,样品中的铅能被定量萃取。方法检出限为0.1 mg/kg。方法用于土壤标准样品测定,测定值与标准值相符,相对标准偏差为1.2%～1.4%,相对误差为0.8%～2.5%。实际土壤样品的测定结果显示,回收率为99.8%～100.4%。     

Pressurised liquid extraction of flavonoids in onions. Method development and validation

A rapid and reliable analytical method for quantification of flavonoids in onions was developed and validated. Five extraction methods were tested on freeze-dried onions and subsequently high performance liquid chromatography (HPLC) with UV detection was used for quantification of seven flavonoids.The extraction efficiencies were lowest for the conventional water bath extraction compared to pressurized liquid extraction (PLE), ultrasonication, ultrasonic liquid processor, and microwave extraction, which yielded similar efficiencies. The reproducibility was in the same range (RSD: 1-11%) for all tested extraction methods. However, PLE was the preferred extraction method because the method can be highly automated, use only small amounts of solvents, provide the cleanest extracts, and allow the extraction of light and oxygen-sensitive flavonoids to be carried out in an inert atmosphere protected from light.The method parameters: extraction temperature, sample weight, flush volume and solvent type were optimised, and a clean-up step was integrated in the PLE procedure by in-cell addition of C18-material to the extraction cells, which slightly improved the recovery and reproducibility of the method. The one-step PLE method showed good selectivity, precision (RSDs = 3.1-11%) and recovery of the extractable flavonoids (98-99%). The method also appeared to be a multi-method, i.e. generally applicable to, e.g. phenolic acids in potatoes and carrots.     

Improved extraction and identification by ultra performance liquid chromatography tandem mass spectrometry of phenolic compounds in burdock leaves

The simultaneous ultrasonic and microwave assisted extraction (UMAE) technique was first employed to obtain phenolics. The effects of UMAE variables including extraction time, microwave power, and solvent to solid radio on the yield of phenolics were investigated. The optimized conditions were as follows: solvent to solid ratio was 20:1 (ml/g), extraction time was 30 s, microwave power was 500 W and two times of extraction. Moreover, the phenolic yield of UMAE was higher than that by maceration, indicating a significant reduction of extraction time and an improvement of efficiency. The phenomenon is related to the strong disruption of leaf tissue structure by microwave induced expansion and ultrasonic shaking, which had been observed with the scanning electron microscopy. The phenolic compositions of the extract was then identified by ultra performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS), 10 compounds had been characterized, providing a more complete identification of phenolic compounds in burdock leaves than previously reported. The occurrence of benzoic acid and p-coumaric acid is reported for the first time. This study suggests that UMAE is a good alternative for the extraction of phenolics, with a great potential for industrial application. Also, UMAE provides a new sample preparation technique for characterization of the phenolic compounds from plants.