A Rapid and Sensitive Determination Method for Soil Nitrate Status

A rapid and sensitive determination method for soil nitrate status is proposed using anion exchange high pressure liquid chromatography. The effect of different extracting solutions and elution-buffer pH is investigated on the determination of NO₂ and NO₃ in standard solutions and various soil extracts in the concentration range of 0–40 ppm. A high lineair correlation is obtained between results from both the Bremner distillation method (1965) and this anion exchange HPLC-method when compared on 69 soil samples. The sensitivity, reliability and ease of handling make anion exchange HPLC a valuable method for the determination of soil nitrate.     

Determination of Atrazine Residues in Electro-Ultrafiltration Soil Extracts by a Sensitive Enzyme Immunoassay

A sensitive enzyme immunoassay (EIA) based on polyclonal antibodies from sheep was used to screen for atrazine in electro-ultrafiltration (EUF) soil extracts without clean-up. Matrix effects were circumvented by diluting the aqueous EUF extracts. The EUF proved to be a convenient method for the extraction of atrazine residues in soil. The efficiency of EUF appeared to be equivalent to that of organic extraction methods except on weathered residues, which generally resulted in lower yields. Both the combined gas chromatography/automated Soxhlet (GC/Soxtec) and the immunochemical technique EIA/EUF yielded similar data for the 26 soil samples identified as positive (> 0.02 mg/kg) during the first screening of 479 EUF extracts by the EIA.     

土壤样品中痕量丁草胺的分析方法

本研究完善了土壤中除草剂丁草胺残留的分析测试方法。在实验室条件下,利用超声提取、弗罗里硅土柱(湿法填柱和干法填柱)进行净化和分离、毛细管气相色谱分析测试,进一步优化了弗罗里硅土柱净化分离丁草胺的条件。土壤中丁草胺的平均回收率为97.46%,检出限为0.002mgkg-1,变异系数小于10%。本方法灵敏度高、重复性好、可排除有机污染物对微量丁草胺残留物测定的干扰,同时减少了有机试剂的用量,适用于土壤样品中痕量丁草胺的分析测试。     

Improved Method for n-Alkanes and n-Methyl-Ketones Determination in Litters and Soils

Eurasian Soil Science - A new technique to extract lipid biomarkers (n-alkanes and n-methyl-ketones) from forest litters and soils using the accelerated solvent extraction (ASE) method was...     

气相色谱法同时测定土壤中13种三嗪类除草剂残留量的方法研究

采用气相色谱-氮磷检测器（GC—NPD）方法,建立了同时测定土壤中13种三嗪类除草剂（脱乙基阿特拉津、莠去通、西玛津、莠去津、扑灭津、特丁津、敌草净、赛克津、西草净、莠灭净、扑草净、异丙净、甲氧丙净）残留量的方法。土壤样品用乙腈-水混合提取剂经超声波提取20min,弗罗里硅土（Florisil）固相萃取柱净化后,毛细管柱分离样品,NPD测定。结果表明,13种三嗪类除草剂在0．05-5．0mg·L^-1范围内线性关系良好,相关系数均大于0．999;添加回收率在72．7％～128．2％之间;相对标准偏差在0．4％～20．5％;方法的检出限在0．001-0．005mg·kg^-1之间。     

紫外分光光度法测定农田土壤微生物生物量氮可行性初探

采用氯仿熏蒸浸提-紫外分光光度法和消化法比较测定了田间定位试验不同施肥处理土壤、添加植物残体土壤、添加葡萄糖土壤的微生物生物量碳、氮(SMBC,SMBN)。结果表明,当土壤微生物生物量氮含量较高时(>20 mg kg-1),采用分光光度法与消化法测定的SMBN具有显著正相关关系(P<0.05),但当SMBN量较低时(<20 mg kg-1)时,分光光度法测定与消化法测定的SMBN没有显著相关性。当土壤中添加麦秸和玉米秸时,土壤浸提液颜色较深(黄色),不适合采用分光光度法测定SMBN。因此,熏蒸提取–分光光度法测定SMBN,仅适于土壤浸提液无色透明、且SMBN含量较高的土壤。     

土壤中双氰胺残留量的检测方法

为检测双氰胺的残留量,在土壤样品加入自制的双氰胺-15N4内标,经超声萃取及冷冻离心处理,采用电喷雾(ESI+)正离子扫描模式,在选择离子监控模式(SRM)下,建立高效液相色谱-串联质谱法定量分析双氰胺的方法。结果表明,该方法在10~50μg·L-1的浓度范围内线性良好,标准曲线回归方程为y=0.9698 x+0.0039,r2=0.9994。方法的检出限与定量限分别为5μg·L-1和16μg·L-1,回收率为97%~104%,RSD1.2%(n=6)。采用该方法检测3类不同的土壤样品,其结果均与理论预期相符。综上,该方法简便、灵敏、准确,为科学施用含双氰胺氮肥的研究提供了一种表征手段。     

土壤中磺胺类抗生素的检测方法优化及残留、降解研究

优化了磺胺甲基嘧啶(SM1)、磺胺二甲嘧啶(SM2)、磺胺对甲氧嘧啶(SMT)、磺胺甲噁唑(SMZ)4种磺胺类抗生素的高效液相色谱(H PLC)检测方法,分析了广州市养殖场周边土壤中磺胺类抗生素的残留特征,并进行了2种磺胺类抗生素的土壤降解试验。结果表明,4种磺胺类抗生素分别在0.10~10μg ml-1范围内线性良好,相关系数R>0.99。确定了最佳提取液为甲醇:含EDTA的Mcllvain缓冲液=1∶1(V/V),4种磺胺类药物的检测限与回收率分别为2.9~4.7μg kg-1、83.6%～90.1%。广州市18个规模化养殖场周边土壤中磺胺类抗生素污染以SM2为主,含量为1.75μgkg-1,其它3种均未被检出。土壤中磺胺类抗生素的含量总体呈随培养时间而不断下降的趋势,SMZ的降解速率大于SM2。     

微波消解法测土壤中全磷和全钾

用微波消解法测定土壤标准样品、标准方法测定消解液P和K含量,通过实验确定最佳消解及分析条件;而且比较微波消解法和传统电热板消解法的精密度和准确度,建立微波消解技术测定土壤P和K前处理方法.结果表明:土壤样品用1∶1HNO3∶HF 10ml的混酸体系进行消解,效果最佳;对于土壤标样,微波消解法测定P和K的相对标准偏差分别为1.46%～3.20%和0.38%～0.84%,电热板消解法测定P和K的相对标准偏差分别为3.06%～4.15%和0.40%～2.08%,微波消解法的测出值均高于电热板消解法;微波消解法的准确度和重现性明显优于电热板消解法,与标准值的相对相差比较,微波消解法都低于5%;两种试验方法样品回收率测得为94%～105%,符合分析方法要求.方法快速简便并有较高准确度、精密度,值得推广和应用.     

山茶根结线虫的LAMP-LFD快速检测方法

为了提高检测效率,本研究利用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)扩增核酸,用横向流动试纸条(lateral flow dipstick,LFD)检测产物,建立了一种山茶根结线虫(Meloidogyne camelliae)的LAMP-LFD快速检测新技术.以山茶根结线虫核糖体DNA内转录间隔区(ribosomal DNA-intemal transcribed spacer,rDNA-ITS)为检测靶标,设计3对特异性引物进行生物素标记的实时荧光LAMP反应,优化后的LAMP扩增条件为63℃反应15 min.比较LFD、实时荧光曲线以及琼脂糖凝胶电泳等3种产物检测方法,结果表明,LAMP产物与异硫氰酸荧光素(fluorescein isothiocyanate,FITC)标记的探针ITS-HP杂交5 min后即可在LFD上显色,从LAMP反应开始到LFD结果判断仅需25min,比常规PCR技术缩短约2h.LAMP-LFD技术能特异性地检测山茶根结线虫,对其基因组DNA的检测灵敏度为4 pg/μL,低于常规PCR方法100倍;对其单条2龄幼虫(J2)检测灵敏度为1/1 000条线虫.本研究建立的快速、灵敏、特异性LAMP-LFD检测技术可应用于山茶根结线虫的口岸检验.     

施肥方式对蔬菜地土壤中8种抗生素残留的影响

从浙江省杭州、嘉兴和绍兴等3个地级市采集了4种不同施肥方式下(分别为施用畜禽粪+化肥、商品有机肥+化肥、沼渣+化肥和单施化肥)的蔬菜地表层土壤样品44个,分析了4类8种抗生素(包括四环素类抗生素的土霉素、四环素和金霉素,喹诺酮类抗生素的恩诺沙星,磺胺类抗生素的磺胺嘧啶、磺胺二甲嘧啶和磺胺甲噁唑及大环内脂类抗生素的泰乐菌素)的残留情况,探讨了施肥方式对蔬菜地土壤中抗生素残留的影响。结果表明,蔬菜地土壤中抗生素的检出率和残留含量与施肥方式密切相关。8种检测的抗生素中土霉素的检出率和残留含量明显高于其他种类的抗生素,土霉素的平均含量占8种抗生素总量平均值的67.03%。抗生素的检出率和平均含量由高至低依次为:土霉素磺胺二甲嘧啶恩诺沙星四环素磺胺甲噁唑、泰乐菌素金霉素磺胺嘧啶;四环素类抗生素磺胺类抗生素。土壤中各类抗生素的检出率及含量均为施用畜禽粪的蔬菜地施用商品有机肥的蔬菜地施用沼渣的蔬菜地单施化肥的蔬菜地,施用畜禽粪的蔬菜地土壤中抗生素残留量明显高于其他蔬菜地。试验结果表明,畜禽粪是蔬菜地土壤抗生素的主要来源,商品有机肥和沼渣的施用对蔬菜地土壤中抗生素的残留也有一定的贡献。     

A Sensitive Spectrophotometric Method for Determination of Trace Quantities of Indium in Soil

A simple and very sensitive method determining microgram quantities of indium in soil has been developed. The spectrophotometric method (??=?1.74?×?10⁵ l mol^-1 cm^-1) based on the mixed complex In (III) with Chrome Azurol S and benzyldodecyldimethylammonium bromide was used for the analysis. A preliminary separation is made by extracting indium into butyl acetate from 5 M HBr solution. The selectivity of indium extraction and determination in the presence of macro- and micro components of soil was studied. Prior reduction of Fe (III) to Fe (II) with ascorbic acid prevents its co-extraction with indium. Indium was determined in synthetic mixtures corresponding to soil compositions and real samples of soil from different agricultural and industrial regions of Poland. The content of indium was found from the calibration graph (in the range, 0.12–0.48 μg/ml; r?=?0.9991) obtained after extraction. The precision was satisfactory: % RSD (n?=?6) ranged from 2.7 to 8.2. The average indium standard recovery ranged from 95 to 101%. Analysis using an ICP-OES method gave comparable results.     

A Rapid Acid-Oxalate Extraction Procedure for the Determination of Active Fe-oxide Forms in Calcareous Soils

Extraction with acid NH₄-oxalate is widely used to estimate the content of “active” forms of Fe oxides in soil. In calcareous soils, this extraction presents some problems (pH change, production of CO₂), which have been circumvented by decalcifying the soil before extraction. However, because of its tediousness, this procedure cannot be applied for routine purposes. In this paper, we describe a rapid procedure in which the soil is treated with oxalic acid before oxalate extraction to neutralize the active calcium carbonate equivalent. The method is simple and provides a useful estimation of the content of active Fe forms that are not occluded in the coarse particles and aggregates of carbonate.     

Rapid and Inexpensive Steam Distillation Method for Routine Analysis of Inorganic Nitrogen in Alkaline Calcareous Soils

Determination of inorganic nitrogen (N) in soil is important in making N fertilizer recommendations for crops. To find a rapid, reliable, and economical method for the estimation of inorganic N in alkaline calcareous soils of Pakistan, three steam distillation methods were compared using soils varying in ammonium (NH₄) and nitrate (NO₃) N contents and other physicochemical properties. In the standard method, the soil sample is shaken with 2 N potassium chloride (KCl) for 1 h, and the extract is then analyzed by steam distillation. In the other two methods, the soil sample is distilled directly with either 2 N KCl or distilled/deionized water. Based on the results of the present work, a method that involves steam distillation with only distilled/deionized water and that requires half the quantity of magnesium oxide (MgO) of the standard method has been proposed, as all the three methods yielded identical results for NH₄- and NO₃-N contents. Being economical, the proposed method for inorganic N estimation by direct distillation of soil with distilled/deionized water deserves consideration for adoption by soil-testing laboratories.     

Quantitation and Reproducibility Problems in Reversed-Phase and Size-Exclusion HPLC Analyses of Wheat Proteins

Reversed-phase (RP-) and size-exclusion (SE-) high-performance liquid chromatography have become important methods for rapid identification of wheat and other cereal cultivars and for revealing quality differences. Accuracy and reproducibility are essential for good results. Due to recent changes in these methods, however, such as using smaller columns, lower flow rates, and smaller samples, small procedural errors become more critical for final results. We therefore further studied the causes and magnitude of problems involving quantitation and reproducibility in RP- and SE-HPLC analyses of wheat proteins. Because of potential problems with protein adsorption to stainless steel system components, we modified systems to contain, insofar as possible, all plastic-type components. Other potentially major problems included weighing flour samples, achieving accurate solvent composition, and interpretation of data. Recognizing and dealing with these problems will enhance the accuracy, reproducibility, and usefulness of HPLC for varietal identification and quality prediction.     

一种简易快速鉴定动物组织总RNA质量的方法

通过一系列的对比实验发现,RNA电泳检测效果不仅与凝胶孔径大小和稀释与否相关,而且也与电泳时间长短和RNA上样量的多少有关。建立了一套可方便快捷地鉴定动物组织总RNA质量的方法,即在孔径宽度为7 mm的1.2% 琼脂糖凝胶上,仅需取3~5 μg 总RNA,加6×RNA上样缓冲液混合并用无RNase的灭菌双蒸水稀释到一定体积后上样,电泳15~30 min即可准确地鉴定RNA的质量。经实践证明,该方法实用性强,重复性好,具有良好的推广应用价值。     

水稻土和湿地土壤有机碳测定的CNS元素分析仪法与湿消化容量法之比较

土壤固碳研究中需要精确的(有机)C计量,而常规的湿氧化法与CNS元素分析仪法测定结果的吻合性足C计量中的问题.国外对旱地土壤的研究表明,这两种方法的结果基本可以对比,但是否同样对于湿地土壤也适用还不清楚.采用CNS元素分析仪(仪器法)和重铬酸钾外加热湿氧化法(容量法)对20个水稻土样品,26个淡水湿地土壤样品和20个沿海湿地土壤样品进行了总有机C(TOC)的对比测定.结果表明,无论是土壤的表土样品还是剖面样品,仪器法测定结果约低于容量法10%以下.两种方法对淡水湿地土壤和水稻土的有机C含量的测定可以对比,但是重铬酸钾氧化容量法对于含氯化物较高的沿海湿地土壤有机C的测定可能不精确.CNS元素分析仪测定的精密度和准确度较高,可以用于各种湿地土壤的C计量.     

分散固相萃取-超高效液相色谱-串联质谱联用快速检测玉米及土壤中莠去津残留

采用分散固相萃取（QuEChERS）为样品前处理方法,建立了超高效液相色谱-串联四极杆质谱快速检测玉米及土壤中莠去津残留分析方法。玉米及土壤样品经乙腈提取、乙二胺-N-丙基硅烷（PSA）分散固相（DSPE）净化后,应用超高效液相色谱/电喷雾串联四极杆质谱仪多离子反应监测（MRM）定量检测,分别以碎片离子m/z216〉146和m/z216〉174定性,以m/z216〉96进行外标法定量。结果表明,在0.005～0.5mg·kg^-1添加水平范围内莠去津的平均添加回收率在77.01%～112.62%之间,相对标准偏差在2.23%～8.43%之间,对莠去津的检出限（LOD）为0.39～0.91μg·kg^-1,定量检出限（LOQ）为1.33～3.02μg·kg^-1。该方法灵敏度高,操作简单,定量准确,测定浓度范围宽,可用于莠去津的残留分析。     

Quantitative Determination of Gluten Protein Types in Wheat Flour by Reversed-Phase High-Performance Liquid Chromatography

A combined extraction-HPLC procedure was developed on a microscale to determine the amounts of the different gluten protein types (ω5-, ω1,2-, α- and γ-gliadins; high molecular weight [HMW] and low molecular weight [LMW] glutenin subunits) in wheat flour. After preextraction of albumins and globulins from flour (100 mg) with a salt solution (2 × 1.0 mL), extraction of gliadins was achieved with 60% aqueous ethanol (3 × 0.5 mL). Subsequently, the glutenin subunits were extracted under nitrogen and at 60°C with 50% aqueous 1-propanol containing Tris-HCl (0.05 mol/L, pH 7.5), urea (2 mol/L) and dithioerythritol (1%). The separation and quantitative determination of gliadins and glutenin subunits was then performed by reversed-phase HPLC on C₈ silica gel at 50°C using a gradient of increasing acetonitrile concentration in the presence of 0.1% trifluoroacetic acid. The flow rate was 1.0 mL/min, and the detection wavelength was 210 nm. Temperature and flow rate were modified for the quantitation of single underivatized HMW subunits. To determine the absolute amounts of protein types, different protein standards (gliadin, LMW and HMW subunits, bovine serum albumin) with known protein contents were compared to HPLC absorbance areas. The calibration curves were almost identical and linear over a broad range (20–220 μg). This extraction-HPLC procedure allows an accurate, reproducible, sensitive, and relatively fast quantitative determination of all gluten protein types in wheat flour, and can be applied to quality evaluation of cereals as raw materials or in processed products.