胂蛋白提取方法的研究

建立了Tris-HCl提取胂蛋白,HNO3-H2O2消解,氢化物发生-原子荧光光谱法测定胂蛋白总量的分析方法。并对Tris-HCl提取海虾中胂蛋白的不同提取条件进行了优化,结果表明:pH为8.5,抽提温度为20℃,抽提时间为30 min,固液比为1:10时胂蛋白的提取率最大;在仪器最佳工作条件下,按实验方法测得方法的检出限(3S/K)为As:0.12μg/L,相对标准偏差(RSD)为0.58%,相关系数为R=0.9997。     

超声波辅助提取柿子树叶单宁的研究

以70%的丙酮溶液为提取溶剂,采用超声波辅助提取野柿叶中的单宁,考察了超声波的功率、提取温度、提取时间等因素对单宁提取量的影响.采用响应面法对提取条件进行优化,并建立了二次回归模型.实验结果显示:当提取温度为52℃、超声波功率为80 W、提取时间为42 min,在此条件下单宁的提取量为203.15 mr/g,比无超声波...     

超声波细胞破碎-高效液相色谱法定性定量分析黄骨鱼皮肤中的着色剂

建立了测定黄骨鱼皮肤中3种合成着色剂(柠檬黄、日落黄和喹啉黄)和3种天然着色剂(叶黄素、β-胡萝卜素和虾青素)的分析方法。样品采用超声波细胞破碎法进行提取,提取不同的着色剂选用不同的提取剂。以叶黄素含量为指标,通过单因素试验确定了超声波细胞破碎法的最佳提取条件:全程时间8 min,超声/间隙时间2s/3s,超声功率比55%,保护温度35℃。采用C18柱(4.6 mm×250 mm,5μm),流速为1.0 m L/min,检测波长为446nm,分离不同的着色剂选用不同的流动相。合成着色剂和天然着色剂分别在2.5~50 mg/L和1.6~32 mg/L范围内呈良好线性,相关系数均大于0.9995。回收率在95.8%~102.5%之间,方法检出限在0.3~1.0 mg/kg之间。用该方法测定了12批次黄骨鱼,均检出含有叶黄素,其余5种未检出。     

高效液相色谱法测定有机肥中洛克沙胂

建立了高效液相色谱(HPLC)-串联紫外检测法检测有机肥中洛克沙胂的分析方法。选用20g·L-1K2HPO4作为提取剂,于60℃温度下超声提取有机肥中的洛克沙胂,采用MAX固相萃取柱净化。结果表明,采用Symmetry ShieldTMRP 18色谱柱,以含0.1%甲酸的0.05mol·L-1 KH2PO4∶甲醇=95∶5(V/V)溶液作流动相,等度洗脱,紫外266nm检测,洛克沙胂的保留时间短,且可完全避开杂质峰的干扰;其平均加标回收率介于81.14%~82.75%之间,相对标准偏差(RSD)7.0%,检出限为20μg·L-1。方法重现性好,精密度高,操作简便,适用于有机肥中洛克沙胂检测。     

鹿茸中18种性激素的提取技术研究

建立一种高效提取鹿茸中雌二醇、雌三醇和睾酮等18种性激素的方法.采用超声波提取法进行提取,液相色谱-串联质谱定性,以回收率为评价指标,分别考察提取溶剂、提取剂用量和提取时间对18种性激素提取效率的影响,并以提取效率实验对建立的方法加以验证.提取溶剂为甲醇,用量为10 m L,超声波提取时间为20 min时,利用优化的超声提取操作步骤进行提取效率实验,18种性激素回收率为73%~116%,实验结果表明在该条件下的超声波提取法快速、准确,重现性好,可同时有效提取鹿茸中的18种性激素,为鹿茸及其制品中性激素前处理提供参考方法.     

超声波提取-气相色谱法测定油田区土壤中21种酚类化合物

采用超声波提取—气相色谱法测定油田区土壤中21种酚类化合物,主要研究了提取时间及净化条件等对测定结果的影响.对比了加压流体萃取与超声波提取方式对回收率的影响,结果表明:超声波提取法回收率优于加压流体萃取法,其中2,4-二硝基酚和4-硝基酚两种化合物比加压流体萃取法回收率提高了30%.以10.0 g土壤样品计,酚类化合物的检出限为0.01～0.05 mg/kg,样品加标回收率为81.5%～110%,精密度为2.6%～11%.经有证标准物质验证,相对误差为2.6%～14%.试验结果表明,超声波提取法适合于油田区土壤中21种酚类化合物的测定.     

液相色谱-氢化物发生-原子荧光联用同时测定洛克沙胂及其代谢物

利用液相色谱-氢化物发生-原子荧光联用技术同时检测5种砷形态化合物(亚砷酸、砷酸、一甲基胂酸、二甲基胂酸和洛克沙胂).结果表明,在梯度洗脱条件下,以C18反相柱作分离柱,含0.5 mmol/L四丁基溴化铵的NaH2PO4-CH3OH溶液为流动相,5种砷化合物得以完全分离;以20 g/L K2S2O8为氧化剂进行紫外消解,7% HCl为载流,20 g/L KBH4为还原剂,砷化合物形成最佳的原子荧光信号.5种砷化合物在一定的浓度范围内与荧光峰面积呈良好的线性关系; 检出限＜10 μg/L; 加标回收率为81.4%～105.6%; 相对标准偏差RSD<4.0%.本方法适用于饲料、鸡粪、土壤和植物样品中洛克沙胂及其代谢物(亚砷酸、砷酸、一甲基胂酸和二甲基胂酸)的含量分析.     

百合多糖的超声波提取工艺研究

以百合多糖的得率为指标,对超声波提取与沸水回流提取进行了比较。采用单因素试验和正交试验对超声波提取百合多糖工艺进行优选。实验表明,超声波提取百合多糖的最佳工艺条件为:提取温度90℃,料液比1∶6,提取3次,提取时间40 min,百合多糖的得率为1.37%。     

何首乌中蒽醌类物质的超声波提取工艺优化

采用超声波辅助法提取何首乌中蒽醌类物质.讨论了甲醇体积分数、提取时间、提取温度、料液比和提取功率5个因素对提取效率的影响;通过正交试验确定了何首乌中蒽醌类物质的最佳提取工艺条件,甲醇体积分数为80%,提取时间为1.0h,提取温度为45℃,料液比为1∶15(g∶mL),提取功率为700W.此条件下蒽醌类物质的最大提取率为1.472 9%.     

高效液相色谱法检测苹果及土壤中福美胂

通过优化提取溶剂和提取方式,确定土壤中的福美胂残留采用苯振荡离心一体提取,苹果用甲苯均质提取,采用高效液相色谱,建立了苹果和土壤中福美胂残留的直接检测方法。采用外标法定量,在0.1~5.0 mg/L范围内,具有良好的线性关系,相关系数为0.9996。当土壤中添加量为0.2~1.0 mg/kg时,回收率在86.0%~103.5%之间,RSD在2.9%~5.0%之间,定量限为0.1 mg/kg;当苹果中的添加量在0.3~2.0 mg/kg时,回收率在91.0%~95.2%范围内,RSD在1.4%~4.7%之间,定量限为0.3 mg/kg。方法应用于实际土壤和苹果样品的福美胂残留量检测,符合农药残留检测的要求。     

Evaluation of the arsenic binding capacity of plant proteins under conditions of protein extraction for gel electrophoretic analysis

As prerequisite for the investigation of arsenic-binding proteins in plants, the general influence of different extraction parameters on the binding behaviour of arsenic to the plant protein pool was investigated. The concentration of the extraction buffer affected the extraction yield both for proteins and for arsenic revealing an optimal buffer concentration of 5 mM Tris/HCl, pH 8. The addition of 1 or 2% (w/v) SDS to the extraction buffer produced a two- to threefold enhancement of the total protein extraction yield but strongly suppressed the simultaneous extraction of arsenic from 80 ± 8% extraction yield obtained without SDS to 48 ± 2% in presence of 2% (w/v) SDS. The arsenic binding capacity of the protein fraction obtained after extraction with Tris buffer and protein precipitation by trichloroacetic acid in acetone was estimated to be 1.4 ± 0.6% independently on the original spiking concentration of arsenic provided in the form of monomethylarsonate to the extracts. Due to the low total protein concentrations of the plant extracts that varied in the range from 75 to 412 μg mL⁻¹ depending on the extraction parameters, high arsenic concentrations of 263-1001 mg (kg protein mass)⁻¹ resulted for spiking concentrations of 10 mg As L⁻¹. The optimized protein isolation procedure was applied to plants grown under arsenic exposure and revealed a similar arsenic binding capacity as for the spiked protein extracts.     

Determination of soluble toxic arsenic species in alga samples by microwave-assisted extraction and high performance liquid chromatography-hydride generation-inductively coupled plasma-atomic emission spectrometry

A microwave-based procedure for arsenic species extraction in alga samples (Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) is described. Extraction time and temperature were tested in order to evaluate the extraction efficiency of the process. Arsenic compounds were extracted in 8 ml of deionised water at 90 degrees C for 5 min. The process was repeated three times. Soluble arsenic compounds extracted accounted for about 78-98% of total arsenic. The results were compared with those obtained in a previous work, where the extraction process was carried out by ultrasonic focussed probe for 30 s. Speciation studies were carried out by high performance liquid chromatography-hydride generation-inductively coupled plasma-atomic emission spectrometry (HPLC-HG-ICP-AES). The chromatographic method allowed us to separate As(III), As(V), monomethylarsonic acid and dimethylarsinic acid in less than 13 min. The chromatographic analysis of the samples allowed us to identify and quantify As(V) in Hizikia sample and Sargasso material, while the four arsenic species studied were found in Chlorella sample. In the case of Laminaria sample, none of these species was identified by HPLC-HG-ICP-AES. However, in the chromatographic analysis of this alga by HPLC-ICP-AES, an unknown arsenic species was detected.     

AB-DTPA浸提-原子荧光法测定土壤中有效砷和有效硒

硒和砷是土壤中重要元素,目前关于提取测定有效硒和有效砷的报道还比较缺乏。本文采用原子荧光光谱法,以AB-DTPA为浸提剂,建立了一种准确测定本地区土壤中有效硒和有效砷的分析方法。通过考察浸提剂加入量,即土液比（m/v）;浸提时的振荡时间和振荡频率的影响,确立了适用于本地区土壤有效硒和有效砷提取分析的有效方法,结果表明：随着浸提剂的不断加入,所测土壤中有效硒和有效砷含量逐渐增大,当土壤称样量和浸提剂使用体积比为1:5时,所测土壤有效硒和有效砷含量最高,继续加入浸提剂后形成稀释效应导致测量结果偏低,故将土液比（m/v）定位1:5;当振荡时间不断增大时,所测所测土壤中有效硒和有效砷含量逐渐增大,振荡时间在30min时,浸提效果最佳,继续增加振荡时间到50min时对浸提效果影响不大,故将30min确立为最佳振荡时间;随着振荡频率的增大,有效硒和有效砷提取量逐渐增加,振荡频率在90-130r/min之间时,浸提效果最好,继续增大振荡频率,所测土壤中有效硒和有效砷含量变化不大。通过上述条件探索,选取五种土壤标准物质（GBW07441,GBW07442,GBW07443,GBW07444,GBW07445）进行验证,结果表明五种不同的土壤标准物质中有效硒和有效砷含量测定值准确,测定误差在-2.84~1.03mg/Kg,相对标准偏差为5.32%~8.85%,精密度和准确度均满足国家相关标准要求。     

Optimisation of sample treatment for arsenic speciation in alga samples by focussed sonication and ultrafiltration

A procedure for arsenic species fractionation in alga samples (Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) by extraction is described. Several parameters were tested in order to evaluate the extraction efficiency of the process: extraction medium, nature and concentration (tris(hydroxymethyl)aminomethane, phosphoric acid, deionised water and water/methanol mixtures), extraction time and physical treatment (magnetic stirring, ultrasonic bath and ultrasonic focussed probe). The extraction yield of arsenic under the different conditions was evaluated by determining the total arsenic content in the extracts by ICP-AES. Arsenic compounds were extracted in 5 mL of water by focussed sonication for 30 s and subsequent centrifugation at 14,000 × g for 10 min. The process was repeated three times. Extraction studies show that soluble arsenic compounds account for about 65% of total arsenic.

An ultrafiltration process was used as a clean-up method for chromatographic analysis, and also allowed us to determine the extracted arsenic fraction with a molecular weight lower than 10 kDa, which accounts for about 100% for all samples analysed.

Speciation studies were carried out by HPLC–ICP-AES. Arsenic species were separated on a Hamilton PRP-X100 column with 17 mM phosphate buffer at pH 5.5 and 1.0 mL min⁻¹ flow rate. The chromatographic method allowed us to separate the species As(III), As(V), MMA and DMA in less than 13 min, with detection limits of about 20 ng of arsenic per species, for a sample injection volume of 100 μL. The chromatographic analysis allowed us to identify As(V) in Hizikia (46 ± 2 μg g⁻¹), Sargassum (38 ± 2 μg g⁻¹) and Chlorella (9 ± 1 μg g⁻¹) samples. The species DMA was also found in Chlorella alga (13 ± 1 μg g⁻¹). However, in Laminaria alga only an unknown arsenic species was detected, which eluted in the dead volume.     

A study on the extraction and quantitation of total arsenic and arsenic species in seafood by HPLC-ICP-MS

Various internal standards and analytical methods were investigated using certified reference materials to evaluate the accuracy of the quantitation of the total As in seafood. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the total arsenic. Enhancement of the total arsenic in its concentration caused by the methanol matrix was clearly observed. Selenium (mass 77) was the best internal standard, and the standard addition method combined with the use of Se as an internal standard was the best analytical method. The total arsenic was determined in bluefin tuna, yellowfin tuna, bigeye tuna, and swordfish by ICP-MS. The concentrations of total arsenic in the seafoods ranged from 0.74 to 6.87 mg/kg.Various extraction procedures were also investigated using reference materials to evaluate the extraction efficiency of the different arsenic species in seafood. Inductively coupled plasma mass spectrometry (ICP-MS) was used in conjunction with high performance liquid chromatography (HPLC) to quantitate the arsenic species in seafood. The arsenic species were extracted from tuna fish (BCR 627) with water/methanol mixtures using sonication, a microwave-assisted system, and ultrasonic processor. The major species was arsenobetaine. The total arsenic extraction efficiency ranged from 81 to 87% for water and various methanol concentrations. Chromatograms of the arsenic species extracted from the Korea Research Institute of Standards and Science (KRISS) tuna, bluefin tuna, yellowfin tuna, bigeye tuna, and swordfish were obtained by the optimum extraction methods and the species were quantified.     

Ultrasound-assisted sequential extraction method for the evaluation of mobility of toxic elements in contaminated soils

A method for the fast sequential extraction of toxic elements in contaminated soil samples using an ultrasonic water bath, followed by determination with inductively coupled plasma optical emission spectrometry (ICP-OES), was developed and compared with other methods introduced in the literature. The five-step sequential extraction (Tessier scheme) was shortened using ultrasound-assisted sequential extraction (UASE). The optimization of the five-step sequential extraction was based on the analysis of SRM 2710 using Tessiers’s method as a reference. Several extracting solutions with different sonication times and temperatures were tested in the optimization procedure. Concentrations of arsenic, cadmium, copper, lead, and zinc were determined in SRM 2710, SRM 2711, and contaminated soil samples with high accuracy and precision. The certified acid-leachable concentrations of the SRM 2710 were obtained for all elements investigated by using an optimized UASE method. Tessiers’s method yielded total element concentrations that were too high. The determination of zinc in SRM 2711 yielded concentrations that were too low, whereas arsenic determination yielded concentrations that were too high by the UASE method and analysis by ICP-OES. The analysis of the SRMs showed that the UASE method is highly comparable with the other methods used for such purposes. The major advantages of the UASE method are the high treatment rate (40 samples simultaneously with a sonication time of 54 min) and a low sample and reagent usage.     

Speciation of dimethylarsinic acid and monomethylarsonic acid by solid-phase microextraction-gas chromatography-ion trap mass spectrometry

A solid-phase microextraction (SPME) method has been developed to determine two methylated arsenic species in human urine samples by GC-MS. The direct extraction of the methyl arsenic compounds by SPME after thioglycol methylate derivatization was studied. Direct extraction with SPME was suitable for the determination of trace levels of dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) in urine samples. Four different commercial SPME fibers were tested for the extraction of methyl arsenic compounds, and the best results were obtained using the polydimethylsiloxane coating. The extraction and desorption time profiles of DMA and MMA were determined. The detection limits for DMA and MMA using the SPME-GC-MS method were 0.12 and 0.29 ng/ml, respectively. The method is linear in the 1 to 200 ng/ml range.     

Slurry sampling hydride generation atomic absorption spectrometry for the determination of extractable/soluble As in sediment samples

A method combining the sampling of slurry pretreated by ultrasonic agitation and microwave assisted extraction with hydride generation atomic absorption spectrometry (HGAAS) for the determination of arsenic in sediment samples is proposed and evaluated. The pretreatment of slurried samples by ultrasonication enabled the extraction of (approximately) up to 85% of arsenic from the studied sediment samples. The further (slight) improvement of the efficiency of extraction was accomplished by the introduction of a short microwave-accelerated treatment. l-cysteine was used as an efficient pre-reduction reagent. The accuracy and precision of the slurry sampling HGAAS method were studied using the certified reference materials: Sediment GBW 30043 (NRCCRM, People's Republic of China), Sediment NIST 2704 (NIST, USA) and Marine Sediment BCSS-1 (NRCC, Canada). The relative standard deviation of the full (overall) analytical procedure was 8.5% and an absolute limit of detection of 2.75 ng was achieved. Factors which influence the reliability of this method are, for example, the choice of slurry liquid phase (extraction medium), sample homogeneity and, in particular, very effective mixing of slurries.     

Ion chromatography-atmospheric pressure chemical ionization mass spectrometry for the determination of trace chlorophenols in clam tissues

A novel analytical method has been developed for the determination of 14 trace chlorophenols in clam tissues by ion chromatography (IC) coupled with atmospheric pressure chemical ionization mass spectrometry (APCI-MS) in the negative mode. The method comprised a fast ultrasound-assisted extraction using a mixture of methanol/water (4:1v/v) containing 5% triethylamine (TEA) as extraction solvent, solid-phase extraction with an Oasis HLB cartridge and gradient separation using KOH/acetonitrile at a flow rate of 1.0 mL/min on an IonPac AG11 guard column (50 mm x 4.0 mm I.D.) and an IonPac AS11 analytical column (250 mm x 4.0 mm I.D.). The molecular ions m/z [M-H](-) 127, 129; 161, 163; 195, 197 and 263, 265, 267 were selected for quantification in the selected ion monitoring (SIM) mode for monochlorophenols (MCPs), dichlorophenols (DCPs), trichlorophenols (TCPs) and pentachlorophenol (PCP), respectively. The average recoveries of the objective compounds spiked in clam tissues were between 80.2% and 98.2%. Within-day and day-to-day relative standard deviations were less than 12.6% and 13.2%, respectively. The optimum IC-APCI-MS conditions were successfully applied to the analyses of 14 trace chlorophenols in clam tissues.     

Development of a rapid extraction procedure for speciation of arsenic in chicken meat

A rapid extraction procedure has been developed for speciation of arsenic in chicken tissue. Water, methanol–water (1:1), and methanol–chloroform (1:1) were tested as extraction media. Individual use of an ultrasonic bath, a microwave oven, or an ultrasonic probe was not sufficient for quantitative recovery of As(III), dimethylarsinate, monomethylarsonate, As(V), and arsenobetaine in spiked samples of chicken tissue. A new extraction procedure using a methanol–water mixture and a microwave oven then an ultrasonic probe enabled extraction of the arsenic species in 7 min with efficiencies ranging from 80 to 100%. HPLC–UV–HG–AFS was used for the determinations. The extraction procedure was 100% efficient when applied to real samples of chicken tissue. AsB (48±5 μg As kg ⁻¹) and one containing-arsenic feed additive, Nitarsone (227±5 μg As kg ⁻¹) were detected.