Ornithine decarboxylase in Saccharomyces cerevisiae: chromosomal assignment and genetic mapping of the SPE1 gene

The gene for ornithine decarboxylase in Saccharomyces cerevisiae, SPE1, has been assigned to chromosome XI by the technique of transverse alternating pulsed field electrophoresis and DNA-DNA hybridization. Genetic mapping by tetrad analysis shows that the SPE1 gene is located on the left arm of chromosome XI, 6 cM from the LAP1 gene and 43 cM from the TRP3 gene. The spe10 mutation previously isolated in this laboratory is mapped to the N-terminal region of the SPE1 gene, and therefore should be designated as a spe1 allele.     

固相萃取-高效液相色谱法(SPE-HPLC)测定环境水体中拟除虫菊酯农药残留

本文采用固相萃取-高效液相色谱法(SPE-HPLC)测定环境水体中七种拟除虫菊酯类农药残留,方法简单、快速、灵敏度高,检测限和回收率令人满意,可应用于环境水体中痕量农药残留的检测。     

计算机拟合技术研究五种酯类的固相萃取条件

利用固相萃取技术富集了水中5种邻苯二甲酸酯类(邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸丁基苄基酯(BBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)、邻苯二甲酸二辛酯(DOP))。借助均匀设计法及计算机回归建模优化技术对5种PAEs的固相萃取条件进行了设计与优化,得到最佳固相萃取条件为:洗脱剂配比(正己烷与丙酮的体积比) 30:1,洗脱体积2 ml,洗脱速率为4 ml·min-1,上样速率8 ml·min-1。富集后的样品用带电子捕获器的毛细管气相色谱检测,方法的线性范围为1～1 000lμg·l-1(DMP,DOP),0．2～100μg·l-1(DBP,DEHP),0．1～100μg·l-1(BBP);线性回归方程的相关系数为0．9970～1．000,检测限为0．01～0．4μg·l-1,方法回收率为69％～116．9％,相对标准偏差为2．5％～9．5％。     

Sample preparation for the analysis of key metabolites from cannabinoids biosynthesis in phytoplankton using gas chromatography–mass spectrometry

Cannabinoids biosynthesis in phytoplankton has attracted much attention due to the rapid development of genetic tools and the optimization of genetic transformation methods in microalgae. To monitor the biosynthesis process, proper sample preparation and practical instrumental methods are needed to measure the various precursors, intermediates, cannabinoids, and their degradation products. The objective of this study was to develop a sample preparation procedure for the quantification of olivetolic acid (OA), cannabigerolic acid (CBGA), cannabidiolic acid (CBDA), tetrahydrocannabinolic acid (THCA), olivetol (OL), cannabidiol (CBD), and tetrahydrocannabinol (THC) using single-quadrupole gas chromatography–mass spectrometry (GC–MS). Isochrysis galbana was used as the model matrix. After methanol extraction, samples were purified using solid phase extraction (SPE), silylated with N-methyl-N-(trimethylsilyl)trifluoroacetamide, and analyzed using GC–MS in electron ionization mode. A strong anion-exchange SPE efficiently recovered OA, CBGA, CBDA, and THCA. A graphitized carbon black SPE was necessary to purify OL, CBD, and THC. Both columns removed amino acids, sugars, polyols, and pigments from the algae extract and prepared samples that are suitable for silylation and GC–MS analysis. The total protocol, including solvent extraction, SPE, silylation, and GC–MS analysis, was validated in accordance with the ICH guidelines. Performance characteristics of our method are superior to existing protocols with similar complexity in the literature.     

固相萃取-高效液相色谱法测定水中氯酚类

采用固相萃取-高效色谱法测定水中酚类。通过正交试验和验证试验探讨固相萃取技术富集水中7种酚类各种因素的影响,优化固相萃取的条件。优化得到的固相萃取条件：样品的pH为2、选择Oasis HLB固相萃取色谱小柱、流速为5mL／min、洗脱溶剂为四氢呋喃、洗脱体积为2mL,分2次洗脱。使用该方法的加标回收率为94．2％～105．1％,相对标准偏差为1．2％～3．9％,检出限为0．1～0．5μg／L。固相萃取-高效液相色谱法不仅各组分的回收率和灵敏度高,而且具有操作简便、溶剂用量少的特点,符合水中酚类测定的要求。     

固相萃取-高效液相色谱测定水果中印楝素残留量

[目的]新建高效液相色谱法测定水果中印楝素的残留。样品用乙腈提取后,经过氨基小柱净化、过0.2μm滤膜,用反相高效液相色谱进行检测。[结果]印楝素在0.5~4.0 mg/L范围内呈良好线形关系(r=0.997),回收率在85.2%~103.6%之间,最低检出限0.2 mg/L,相对标准偏差在2.28%~10.84%之间。[结论]方法简便、重现性好,可用于水果中印楝素残留的检测。     

固相萃取-液质联用法测定食品中两种苯氧乙酸类除草剂含量

建立了固相萃取-液质联用法测定食品中2,4-二氯苯氧乙酸(2,4-D)和2-甲-4-氯苯氧乙酸(MCPA)含量的方法。样品经0.01 mol/L氢氧化钠碱液提取后,用甲酸溶液调至酸性(pH=3.0),以Oasis HLB柱净化富集,在HPLC-MS(SIR)模式下进行定性定量分析。结果表明,2,4-D和MCPA溶液在0.005~0.32μg/mL内呈良好的线性关系,相关系数r分别为0.999 3和0.999 6,检出限(S/N=3)分别为1.35,1.31μg/L,富集倍数为49和51,加标回收率为78.75%~103.75%。本法操作简便、结果准确、重复性好,是测定食品中残留2,4-D和MCPA含量的有效方法。     

Effects of field-manure applications on stratified 17β-estradiol concentrations

The occurrence of the manure-borne estrogen, 17β-estradiol (E2), was investigated in laboratory and field soils. In the laboratory, E2 was applied to soil to simulate concentrations found in swine (Sus scrofa domestica) manure (5000 ng L⁻¹). The aqueous-extracted E2 dissipated in the soil by 98% within 1 h and was not significantly different from background concentrations (18 ng L⁻¹) for the duration of the experiment (64 h). In the field study, soil cores were taken before and several dates after swine manure application. Equivalent porewater concentrations of water-extractable E2 were determined in 0.15-m increments down to the water table (0.70-2.00 m deep). The average frequency of detection for 168 samples was 38% (average = 40 ng L⁻¹ porewater equivalents). Eleven days after manure application there was no significant effect on E2 detection frequency or concentration. However, E2 concentrations significantly increased by 6 months after manure application, and appeared to be related to precipitation. Concentrations then returned to original levels by 17 months after manure application. Manure did not have an immediate effect on E2 occurrence due to the capacity of the soil to rapidly sorb E2. However, it appears that soil may act as a long-term reservoir for E2 in the environment, which may be periodically released through desorption.     

固相萃取净化-高效液相色谱法测定食品中α-细辛醚和β-细辛醚残留量

建立用于测定乳粉、绿豆糕、猪肉、熏鱼肉、调味粉中白菖蒲油主要成分α-细辛醚和β-细辛醚含量的固相萃取-高效液相色谱分析方法。选择乙腈提取样品中的细辛醚,提取液经硅胶固相萃取小柱净化,采用配备荧光检测器的高效液相色谱仪进行分离测定,外标法定量。乳粉、绿豆糕、猪肉、熏鱼肉、调味粉中α-细辛醚和β-细辛醚的方法定量限均为0.01 mg/kg,在0.01~0.50 mg/kg的添加水平范围内,α-细辛醚的平均回收率在78.2%~99.4%之间,β-细辛醚的平均回收率在80.8%~105.6%之间,相对标准偏差为1.6%~10.3%。该方法能够满足食品中细辛醚的痕量检测要求。     

固相萃取-高效液相色谱-串联质谱法同时检测鸡蛋及其制品中8种兽药残留

目的 建立一种快速、高效的固相萃取-高效液相色谱-串联质谱法同时测定鸡蛋及其制品中的中甲硝唑、地美硝唑、氯霉素、氟苯尼考、甲砜霉素、尼卡巴嗪、金刚烷胺和灭蝇胺8种兽药的分析方法。方法 样品前处理采用80%乙腈(含0.1%甲酸)提取,经PRiME HLB小柱净化后检测。以乙腈-0.05%甲酸为流动相,在质谱检测器的多反应监测模式下进行分析。结果 8种兽药组分在1.0~200.0 ng/mL浓度范围内线性关系良好,相关系数r2为0.9982~0.9999,检出限范围为0.3~5.0 μg/kg,定量限范围为1.0~10.0 μg/kg。加标实验分别添加低、中、高的3个水平浓度,加标回收率达到83.6%~96.2% (n=5)。结论 该方法具有前处理简单、灵敏度高和检测速度快的优点,适用于鸡蛋及其制品中8种兽药组分的同时监测和分析。