土壤中多种拟除虫菊酯类农药残留的提取与检测方法

研究建立了土壤中甲氰菊酯、三氟氯氰菊酯、顺式氯菊酯、反式氯菊酯、氯氰菊酯、氟氰戊菊酯、氰戊菊酯和溴氰菊酯8种拟除虫菊酯类农药残留的超声提取-硅胶柱净化-气相色谱(GC)检测方法。以石油醚/丙酮(v/v,2:1)溶液为有机提取剂,超声提取土壤样品,旋转蒸发仪浓缩,经自制硅胶柱以10 ml石油醚/乙酸乙酯(v/v,9:1)溶液进行分离净化并浓缩后用正己烷定容,样品采用气相色谱法FID检测器检测。研究结果表明,该方法对土壤样品中8种拟除虫菊酯的加标回收率较高,平均值在84.9%~101.3%之间。通过实验优化了8种拟除虫菊酯类化合物的分离和测定条件。该提取和检测方法具有简便、快捷、成本低、净化效果和重现性好等特点,适合于土壤中痕量拟除虫菊酯类农药残留的测定。     

高效液相色谱法同时测定土壤中环丙氨嗪和三聚氰胺

本试验研究建立了同时测定土壤中环丙氨嗪和三聚氰胺残留量的高效液相色谱法.红壤、潮土等5种土壤样品经氨水/甲醇 (5/95,v/v)超声提取3次,浓缩处理后上机检测.环丙氨嗪和三聚氰胺的标准曲线在0.1 ～ 15.0 μg/ml浓度范围内线性关系良好,绝对系数(R2)分别为1.0000和0.9998;在0.5 ～ 5 mg/kg添加范围内,环丙氨嗪和三聚氰胺在土壤中的平均回收率分别为87.2% ～ 101.1% 和 75.3% ～ 101.6%,变异系数分别为3.3% ～ 8.1%、1.6% ～ 9.9%,最低检测限分别为0.05 mg/kg、0.07 mg/kg.与国际上气相/液相色谱-质谱连用法相比,操作简单,经济方便易于普及.     

高效液相色谱法测定土壤中均三氮苯类除草剂

采用高效液相色谱法测定土壤中7种均三氮苯类除草剂:西玛津、阿特拉津、扑灭通、莠灭净、扑灭津、扑草净、去草净。用乙腈或甲醇:乙腈(3:7v/v)在索氏提取器上提取土壤中的7种均三氮苯类除草剂,提取液经旋转蒸发,氮吹浓缩,中性氧化铝小柱净化,再次氮吹浓缩后,高效液相色谱二极管阵列检测器检测,外标法定量,检测波长为224nm。实验结果表明该方法的变异系数在1.24%～6.83%之间,平均回收率在95.0%～106.9%之间,检出限为0.84～2.07μg/kg。该方法是分析土壤中均三氮苯类除草剂农药的一种较为理想的方法。     

ASE-HPLC-MS/MS法测定土壤中四环素类抗生素残留

通过优化ASE萃取参数和固相萃取净化条件,建立了土壤中4种四环素类抗生素残留的加速溶剂萃取-液相色谱串联质谱测定方法。选择EDTA-McIlvaine∶甲醇=1∶2(V/V)作为萃取溶剂,应用Oasis-MAX强阴离子交换柱进行样品的富集和净化,乙腈∶0.4%甲酸溶液=22∶78(V/V)条件下进行色谱分离,ESI正离子源和多反应监测模式(MRM)下测定,方法检测限为2.2～3.2μg.kg-1,定量限为22～32μg.kg-1,样品加标回收率在60.1%～103.8%之间,相对标准偏差为2.6%～4.8%。本方法具较高灵敏度和准确度,能满足土壤中μg.kg-1痕量水平4种四环素类抗生素残留测定要求。     

不同碳氮比有机肥对有机农业土壤微生物生物量的影响

有机肥能提高土壤微生物活性, 改善土壤品质。碳氮比是影响有机肥肥效的重要因素。本试验以无肥处理为对照(CK), 设置4个有机肥碳氮比处理(20︰1、15︰1、10︰1、5︰1), 在温室中进行茄子盆栽试验, 定期采集土壤样品, 用熏蒸提取法测定土壤微生物生物量碳(SMBC)、氮(SMBN), 研究等氮条件下不同碳氮比有机肥料对土壤生物活性的影响。试验结果表明, 不同碳氮比的有机肥均能提高土壤的SMBC和SMBN含量, 具体表现为SMBC: 20︰1>10︰1≈15︰1>5︰1>CK, SMBN: 15︰1>10︰1>20︰1>5︰1>CK。SMBC/SMBN的比率反映土壤氮素生物活性, 其值越低, 生物活性越大, 氮素损失越少, 本试验SMBC/SMBN表现为: 15︰1<10︰1<20︰1≈5︰1相似文献   

土壤中土霉素残留的高效液相色谱检测方法

为有效测定土壤中土霉素残留量,建立了固相萃取－高效液相色谱法提取以及测定潮土、红壤、紫色土中土霉素残留量的方法。土壤中土霉素残留经提取缓冲溶液进行有效提取,经过DVB固相萃取小柱纯化、无水甲醇洗脱和氮气流浓缩后,经HPLC测定。对提取缓冲液、流动相以及流动相pH值、有机相与无机相的比例以及流速等测定条件进行优化研究。结果表明：提取液为Na2EDTA-Mcllvaine,流动相为乙腈∶0.01mol/L磷酸二氢钠（pH值2.5,V∶V=10∶90）,温度25℃,流速1.2ml/min,检测波长350nm对3种不同性质的土壤中土霉素残留量的测定最为合适。应用本方法进行土壤中土霉素残留量的测定,土霉素含量与峰面积具有良好的线性关系,相关系数（n=9）分别为红壤0.997,紫色土0.995,潮土0.987;检出限分别为红壤0.11mg/kg,紫色土0.17mg/kg,潮土0.09mg/kg;回收率(n=18)分别为红壤80.7%~128.8%,紫色土70.5%~100.0%,潮土61.5%~103.9%;相对标准偏差(RSD, n=18)分别为红壤7.1%~28.2%,紫色土11.9%~38.1%,潮土4.1%~17.0％。本方法简便、准确,适合于测定不同土壤中土霉素残留量,结果可靠。     

土壤磺胺类抗生素固相萃取-高效液相色 谱法的构建与优化

设计正交试验对红壤中磺胺甲恶唑(sulfamethoxazole, SMZ)的萃取方法进行优化,并结合高效液相色谱,构建了固相萃取-高效液相色谱联合测定法(SPE-HPLC),并将该方法应用于不同抗生素以及不同类型土壤中SMZ的提取测定。结果表明,在以乙腈–磷酸盐缓冲液为提取液、提取液量为10 ml、超声时间为15 min、9 ml甲醇淋洗固相萃取柱(HLB)的条件下,红壤中SMZ的提取效果最优,0.25 mg/kg的SMZ回收率达到85.58%,能够满足环境样品的分析要求。利用该法提取测定红壤中不同抗生素包括3种磺胺类抗生素(磺胺嘧啶、磺胺二甲基嘧啶、磺胺甲基嘧啶)和2种四环素类抗生素(土霉素、盐酸四环素),结果表明,当抗生素浓度为0.25 mg/kg时,磺胺类抗生素(SAs)的回收率范围在67.31%～85.58%,四环素类抗生素(TCs)的回收率范围在20.81%～59.33%。利用该法分别提取测定不同类型土壤中的SMZ回收率,得到潮土中SMZ的回收率最大,达到92.92%,其次为荒漠土、红壤、紫色土,最低的回收率出现在黄棕壤,仅为53.62%。据相关性分析表明,回收率与土壤电导率(EC)、微生物碳氮比(C/N)呈极显著负相关(P0.01),与阳离子交换量(CEC)、有机质(SOM)呈显著负相关(P0.05)     

土壤和堆肥中四环素类抗生素的检测方法优化及其在土壤中的降解研究

在对土霉素(OTC)、四环素(TC)和金霉素(CTC)3种四环素类抗生素的高效液相色谱(HPLC)检测分析方法以及在土壤和堆肥中的提取方法进行改进和优化的基础上,采用该方法进行了3种抗生素在土壤中的降解试验。结果表明,选用Agilent Eclipse XDB-C8(4.6×150 mm,5μm)色谱柱,以0.01 mol/L草酸/乙腈/甲醇(79/10.5/10.5,v/v/v)为流动相,紫外检测波长268 nm,流速1.0 mL/min,进样量5μL,采用外标法定量,可使3种四环素类抗生素在20 min内全部洗脱并达到基线分离;在0～10 mg/L范围内,抗生素浓度与峰面积呈显著的线性关系,相关系数(r)均0.999。土壤和堆肥样品中的OTC、TC和CTC可用1 mol/L NaCl/0.5 mol/L草酸/乙醇(25/25/50,v/v/v)混合溶液提取,其回收率在76.0%～92.5%之间。加入到土壤中的抗生素在25℃下避光培养49 d后,在壤土和红土中的降解率分别是67%～72%和36%～46%,对应的半衰期分别为26～30 d和46～75 d,说明抗生素在壤土中比红土中容易降解。此外,3种抗生素在壤土中的半衰期没有显著性差异,而在红土中CTC和TC的降解速率显著高于OTC。     

超声提取-离子色谱法测定土壤中10种水溶性阴离子

采用超声提取–离子色谱法测定了土壤中F~–、CN~–、BrO_3~–、Cl~–、NO_2~–、Br~–、NO_3~–、PO_4~(3–)、SO_4~(2–)、C_2O_4~(2–)等10种水溶性阴离子含量。样品中阴离子用水浸提,提取条件为:固液比1:10,温度30℃,超声振荡时间30 min。提取完成后离心,取上清液通过0.22μm滤膜过滤后测定。在选定的离子色谱测定条件下,10种被测阴离子的检出限为0.009 7～0.31 mg/kg,不同阴离子的加标回收率为84.0%～112%,相对标准偏差(n=7)为0.09%～4.3%。     

高效液相色谱法测定栀子苷的含量

建立了一种快速测定栀子及栀子黄中栀子苷含量的高效液相色谱分析方法。采用超声波法提取栀子苷,使用Shimpack HRC-ODS色谱柱(4.6mm×250mm,5μm),以甲醇-水(30:70,V/V)为流动相,采用二极管阵列检测器(检测波长240nm)对栀子苷进行测定。结果表明,采用超声波法提取1.0h可将栀子苷提取完全,在2~24μg/ml范围内栀子苷含量与峰面积呈良好的线性关系,相关系数r=0.9986,精密度和稳定性试验相对标准偏差均小于5%,加样回收率达到98.13%。该测定方法简单、准确、精密度高、重现性好。     

High pressure liquid chromatographic detection and estimation of furazolidone and nitrofurazone in animal feeds.

The feed sample is extracted with acetone or dimethylformamide-acetone (1 + 1) and the filtered extracts are evaporated to dryness. The residue is dissolved in chloroform and transferred to a silica gel column. The nitrofurans are eluted with methanol-chloroform (50 + 50). A portion of the eluate is evaporated to dryness and the residue is redissolved in a small volume of methanol. Aliquots of the methanolic solution are injected into a liquid chromatograph with a muBondapak C18 column, using 30% acetonitrile as the eluting solvent and ultraviolet detection at 365 nm. Several samples spiked with 0.5--50 ppm furazolidone or nitrofurazone and 2 commercial samples were analyzed by the proposed method.     

Simultaneous fluometuron and norflurazon analysis in soil extracts and leachates

Abstract

Rapid, methanol‐extraction techniques for fluometuron (N, N‐dimethyl‐N'‐[3‐(trifluoromethyl) phenyl] urea) and norflurazon (4‐chloro‐5‐(methylamino)‐2‐(3‐(trifluoromethyl)phenyl)‐3(2(H)‐pyridazinone) from fortified soils have been reported to attain >90% recoveries. Analytical methods involving chromatographic separation coupled with fluorescence detection have also been described. The objectives of this study were to describe an analytical method for the simultaneous detection of fluometuron and norflurazon using ultraviolet spectro‐scopy in soil leachates and extracts and to examine the influence of residence time on herbicide recovery from fortified soil. The analytical method requires a gradient HPLC system, a reverse‐phase C‐18 column, and ultraviolet spectroscopy at a wavelength of 240 nm. The method is characterized by high reproducibility (spike recovery and diluted sample results are generally within 10% of the expected herbicide concentrations), low limits of detection (less than 1 (μg/L in soil leachates and 20 μg/L in soil extracts, depending on organic carbon content), and an applicable concentration range of more than two orders of magnitude. The recovery of fluometuron and norflurazon from fortified soils was significantly influenced by equilibration time, loading rate, and soil type (assuming zero chemical degradation). Most significantly, as herbicide contact time with the soil increased, recovery decreased. Thus, herbicide recoveries determined in the laboratory may not provide a true measure of herbicide recoveries from field soils.     

Extraction and colorimetric determination of azadirachtin-related limonoids in neem seed kernel.

A colorimetric method was developed for the determination of total azadirachtin-related limonoids (AZRL) in neem seed kernel extracts. The method employed acidified vanillin solution in methanol for the colorization of the standard azadirachtin or neem seed kernel extracts in dichloromethane. Through the investigation of various factors influencing the sensitivity of detection, such as the concentration of vanillin, acid, and the time required for the formation of color, optimum conditions were selected to perform the assay. Under the optimum conditions, a good linearity was found between the absorbance at 577 nm and the concentration of standard azadirachtin solution in the range of 0.01-0.10 mg/mL. In addition, different extraction procedures were evaluated using the vanillin assay. The HPLC analysis of the extracts indicated that if the extractions were performed in methanol followed by partitioning in dichloromethane, approximately 50% of the value determined by the vanillin assay represents azadirachtin content.     

土壤中有效钼的极谱(催化波)测定方法

土壤中钼的含量很低,根据现有资料,我国土壤中钼的平均含量是1.7ppm,有效态钼的含量更少,一般在0.1ppm以下.为了明确土壤的含钼量和合理施用钼肥来提高农作物产量,有必要测定土壤中有效态钼.过去习用的测定方法是硫氰酸钼比色法和极谱法^[3],测定下限为1ppm,因此取样量大,分离手续烦琐,分析过程冗长,每周每人仅能分析10个左右标本.     

Evaluation and validation of a commercially available enzyme-linked immunosorbent assay for the neonicotinoid insecticide imidacloprid in agricultural samples

The performance of a commercially available microtiter plate ELISA kit for the determination of the neonicotinoid insecticide imidacloprid was evaluated for sensitivity, selectivity, influence of organic solvent used for extraction procedure, matrix interference originated from agricultural sample, accuracy, and method comparison with conventional HPLC analysis. The limit of detection for the kit (0.1 or 0.5 ng/mL) was determined. The working range (1-39 ng/mL) experimentally calculated on the basis of a criterion, which is determined as the range from I(20) to I(80), was comparable to that established by the manufacturer (1-50 ng/mL). The linearity of the standard curve based on the kit-assembled standard solutions agreed with the one based on the self-made standard solutions. Specificity studies indicate that the imidacloprid monoclonal antibody can readily distinguish the target compound from other structurally related neonicotinoid analogues and some metabolites, with the exception of clothianidin, the cross-reactivity of which was approximately 12%. To extract imidacloprid from an agricultural sample (apple) as simply and rapidly as possible, some extraction methods were examined. Consequently, the extraction method with hand-shaking for 5 min was the best among the examined methods. For the analysis of imidacloprid in apple samples, it was extracted directly with methanol and the extracts were diluted 10-fold (100-fold in the well) with water prior to ELISA analysis. No significant matrix interference was observed with the dilution factor. Recoveries of imidacloprid from fortified apple samples ranged from 87.7 to 112.0%. The results obtained with the ELISA kit correlated well with those by the reference method (conventional HPLC analysis) for apple samples (r > 0.998). These findings strongly indicate that the ELISA kit may be employed routinely for an on-site imidacloprid residue analysis of apple samples.     

土壤和番茄中氯虫苯甲酰胺的残留检测与消解动态研究

研究和建立了氯虫苯甲酰胺在土壤和番茄中的液相色谱检测方法,并采用田间试验方法研究了氯虫苯甲酰胺在土壤和番茄中的残留消解动态规律。结果表明,采用甲醇溶液浸泡提取,减压浓缩后用二氯甲烷萃取,浓缩后用二氯甲烷定容,液相色谱仪带二极管阵列检测器（DAD）测定,外标法定量。在0.05～0.5mg·kg-1添加水平范围内,土壤和番茄中氯虫苯甲酰胺的添加平均回收率为91.43%～100.91%,变异系数为3.53%～9.71%;土壤和番茄中氯虫苯甲酰胺的最小检出量均为1.0×10-7g,最低检出质量分数为0.005mg·kg-1。田间残留试验表明,氯虫苯甲酰胺在土壤和番茄中残留消解动态规律符合方程Ct=C0e-kt;150g·L-1高效氯氟氰菊酯·氯虫苯甲酰胺微囊悬浮-悬浮剂在土壤和番茄中的消解半衰期分别为6.55～11.49d和3.82～10.70d。最终残留试验研究表明,在番茄上手动喷雾施药150g·L-1高效氯氟氰菊酯·氯虫苯甲酰胺微囊悬浮-悬浮剂,按推荐剂量和1.5倍推荐剂量施药,兑水喷雾处理2～3次,施药间隔为7d,最后一次施药距采收间隔7d时,氯虫苯甲酰胺在番茄中最高残留量均小于0.3mg·kg-1。参照欧盟等规定的氯虫苯甲酰胺在番茄中最大残留限量标准,按照推荐剂量和1.5倍推荐剂量施药2～3次,距最后一次施药7d时,氯虫苯甲酰胺在番茄上残留是安全的。     

Extraction of polyphenols from processed black currant (Ribes nigrum L.) residues

The total phenol and anthocyanin contents of black currant pomace and black currant press residue (BPR) extracts, extracted with formic acid in methanol or with methanol/water/acetic acid, were studied. Anthocyanins and other phenols were identified by means of reversed phase HPLC, and differences between the two plant materials were monitored. In all BPR extracts, phenol levels, determined by the Folin-Ciocalteu method, were 8-9 times higher than in the pomace extracts. Acid hydrolysis liberated a much higher concentration of phenols from the pomace than from the black currant press residue. HPLC analysis revealed that delphinidin-3-O-glucoside, delphinidin-3-O-rutinoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside were the major anthocyanins and constituted the main phenol class ( approximately 90%) in both types of black currant tissues tested. However, anthocyanins were present in considerably lower amounts in the pomace than in the BPR. In accordance with the total phenol content, the antioxidant activity determined by scavenging of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation, the ABTS(*)(+) assay, showed that BPR extracts prepared by solvent extraction exhibited significantly higher (7-10 times) radical scavenging activity than the pomace extracts, and BPR anthocyanins contributed significantly (74 and 77%) to the observed high radical scavenging capacity of the corresponding extracts.     

Analysis of free and esterified ergosterol in tomato products

A new extraction and chromatographic procedure to quantify free and esterified ergosterol in tomato products was devised. The extraction solution was composed of a dichloromethane/methanol mixture in a 2:1 (v/v) ratio. This extraction solvent allowed for higher ergosterol recovery from tomato products (an average of 25% more) compared to hexane, which is frequently employed for ergosterol extraction. Both free and esterified ergosterol were determined by HPLC reverse-phase chromatography employing a Nova-Pak C-18 column (300 x 3.9 mm), filled with 4 mm average particle size and a guard column of the same material. The elution was performed at a flow rate of 1 mL. min(-1) with a linear gradient of solvent A (methanol/water, 80:20, v/v) and solvent B (dichloromethane). The gradient, starting at sample injection, was from 0 to 50% B for 20 min for the free ergosterol analysis and additional 15 min at 50% B to analyze the ergosterol esters. This technique has proven to be more sensitive for ergosterol determination than other reported chromatographic procedures. Moreover, ergosterol esters, extracted from various fungal sources, separated well and were easily quantified.