甜菜抗氧化性的电喷雾串联质谱研究

使用电喷雾质谱检测了糖用甜菜水提取液和乙醇提取液,并且采用串联质谱技术分析了这些提取液中化合物的碎裂规律。实验结果表明水提取液和乙醇提取液都适合在电喷雾正离子模式和负离子模式下检测,说明甜菜中化学成分复杂,种类较多。在串联质谱中,这些成分大多丢失水、二氧化碳、葡萄糖等中性碎片,说明这些化合物含有羟基、羧基、葡萄糖基,这些基团在化合物抗氧化性能中都起到重要作用,这些与文献中的研究结果相同。说明使用电喷雾质谱技术分析甜菜的抗氧化性能十分可靠,甜菜提取液不需经过复杂的前处理就可以检测,操作简单、快速,灵敏度高,可以用于复杂体系抗氧化性的快速筛选。     

电喷雾串联质谱法鉴定甜叶菊干叶中甜菊糖苷的结构

为了对甜叶菊中甜菊糖苷类成分的结构进行鉴定.建立了一种利用电喷雾质谱法鉴定甜叶菊中甜菊糖苷类结构的方法,与液质联用技术不同,该方法不需要复杂的前处理过程,能够直接判断样品中含有的多种甜菊糖苷.结果表明,对甜叶菊中的甜菊糖苷进行电喷雾质谱研究,正离子模式下电离成加氢、钠、钾离子,负离子模式下电离成减氢、加氯离子,并在负离...     

快速滤过型净化法应用于气相色谱—串联质谱检测大豆中农药残留

为研究快速滤过型净化法(m-PFC)对大豆基质中14种常见农药残留气相色谱-串联质谱(GC-MS/MS)同时检测的适用性,本研究选取两种快速滤过型净化柱(m-PFC柱)作为净化手段,利用气相色谱-串联质谱进行检测分析,以外标法作为定性定量依据对14种农药进行测定,通过对基质效应、净化效果、回收率、多次滤过效果等方面进行评价。结果显示：多数农药在大豆基质中的基质效应影响无法忽略,14种农药在0.005～0.5 mg·mL^-1范围内线性关系良好,回收率为85%～110%,RSD为4.3%～10.2%,m-PFC柱2(150 mg无水硫酸镁,25 mg MWCNTs, 25 mg C₁₈,25 mg PSA)的净化效果更好,两次滤过次数的净化效果、检测准确度、重复性更佳。本方法可对大豆中14种农药进行快速测定,操作简单,效率高,亦具备一定的普适性,可以作为大豆中其他农药残留检测的参考方法。     

QuEChERS-GC-MS/MS测定茶叶中八氯二丙醚(S-421)残留量

八氯二丙醚(S-421)被广泛地作为农药增效剂。在农药、蚊香中使用,使其在茶叶中也有一定的残留。与已有的标准方法SN/T 1774-2006对比,是一种简便、快速测定茶叶中八氯二丙醚农药残留的方法。利用气相色谱-串联质谱(GC-MS/MS)检测技术,采用QuEChERS法作为样品前处理方法。通过保留时间、选择离子及其相对丰度定性,外标法定量。结果表明,八氯二丙醚的线性范围为0.006-0.06 μg/mL,线性相关系数0.999,加标回收率为83 %-92 %,相对标准偏差小于10 %。 该方法的检出限为0.001 mg/kg。     

分子印迹固相萃取和电喷雾质谱法联用测定茶叶中四种儿茶素

为了对茶叶样品中微量儿茶素进行快速准确分析,利用分子印迹固相萃取(MIPs-SPE)与电喷雾质谱(EIMS)联用技术进行了茶叶中四种儿茶素—表儿茶素(EC)、表没食子儿茶素(EGC)、表儿茶素没食子酸酯(ECG)、表没食子儿茶素没食子酸酯(EGCG)的分离测定。首先以表儿茶素(EC)为模板分子,采用紫外聚合方法合成分子印迹聚合物(EC-MIPs),功能单体为甲基丙烯酸(MAA),交联剂为乙烯二醇二甲基丙烯酸酯(EDMA),引发剂为偶氮二异丁腈(AIBN)。利用EC-MIPs作为固定相制备EC-MIPs-SPE柱,对茶叶样品进行分离萃取后采用EIMS对洗脱液中儿茶素单体进行检测,分别与常规C18和非分子印迹聚合物(NIP)固相萃取方法进行比较。结果表明EC-MIPs-SPE法对儿茶素类单体有特异性识别能力,对茶中主要干扰物质咖啡因、茶碱的结合能力远小于儿茶素分子。最佳萃取条件为:水相上样,用50%(v/v)甲醇/水溶液淋洗除去非特异性结合干扰物,1%(v/v)醋酸的甲醇洗脱特异性结合的四种儿茶素单体。对真实茶叶样品测试发现:经过EC-MIPs-SPE法预富集,可以去除94.2%的咖啡因和全部茶碱干扰,同时可得四个主要儿茶素信号,相对强度分别为:EC(12.1%),EGC(8.2%),ECG(35.4%),EGCG(45.7%)。本法可特异性地识别和分离儿茶素单体,有效消除咖啡因和茶碱干扰,可用于茶叶中微量儿茶素分离鉴定。     

水稻根尖质膜蛋白质组学研究方法的建立

以徐稻3号水稻苗期幼嫩根尖为材料,利用葡聚糖/聚乙二醇两相分配法纯化得到纯度达 90% 的质膜组分,使用优化的双向电泳水化液溶解质膜蛋白,通过等电聚焦/十二烷基磺酸钠 聚丙烯酰胺凝胶双向电泳 （IEF/SDS PAGE）分离和基质辅助激光解吸电离串联飞行时间质谱（MALDI TOF/TOF）分析,鉴定了31个水稻质膜相关蛋白。结果表明IEF/SDS PAGE 双向电泳适合分离亲水性相对较高的膜附着蛋白。进一步利用高盐和温和去污剂对纯化的质膜进行洗涤,以降低质膜组分的复杂程度,通过 SDS PAGE 单向电泳分离和液相色谱串联质谱（LC MS/MS）分析,鉴定了 8个质膜蛋白。经洗涤后的质膜组分复杂度显著降低,SDS PAGE 中的蛋白条带只包含1~2 种蛋白,且主要为疏水性较强的穿膜蛋白,说明多种生物化学分离方法及不同质谱分析的综合运用,是解决生物膜蛋白质组学难点的有效途径。     

HPLC-MS/MS法测定花生中5种常用农药残留量

为同步检测花生中5种常用农药残留量,采用液-液分配反提取方法,对花生中乙草胺、异丙甲草胺、涕灭威、吡虫啉、辛硫磷等5种农药同步提取、净化与浓缩,高效液相色谱-串联质谱进行测定。结果表明:当加标水平为0.01、0.05、0.10μg/m L时,平均加标回收率为80.9%~108.5%,相对标准偏差为1.5%~7.8%,该方法操作简单,不需要特殊的试剂和仪器,成本低,检出限及定量限低于国家最大残留限量值,检测灵敏度高,各项指标均符合国家农药残留分析质量控制标准,能满足实际样品检测需要。     

普洱茶粉挥发性成分全二维气相色谱/飞行时间质谱研究

以非极性柱Rxi-5Sil MS为第一维柱,中等极性柱Rtx-200为第二维柱,对普洱茶粉的挥发性成分进行全二维气相色谱-飞行时间质谱分析。结合飞行时间质谱普检索图库与全二维特有结构信息谱图,鉴定出相似度大于800、含量≥0.1%的物质90种,占总峰面积的66.306%。研究结果表明,全二维气相色谱-飞行时间质谱联用系统的高分离度、高峰容量和高灵敏度,以及全二维分离特有的结构谱图特征,非常适合于普洱茶粉中复杂挥发性组分的研究。     

第六讲 茶叶中农药多残留检测(气相色谱-质谱法)

一、气相色谱-质谱法多残留检测方法概况 随着质谱仪器和计算机技术的发展，质谱的灵敏度、扫描速度、谱库检索、谱图的后处理等都有了很大提高，气相色谱-质谱联用检测技术也得到发展，同时近年农产品中农药残留检测前处理技术的提高，使得用气相色谱-质谱联用技术检测农产品中多种农药成为现实。国际上有加拿大、13本等国的200多种农药在农产品中的多残留测定方法，我国的国标方法GB／T20768--2006、GB／T20769--2006可对400～500种农药残留进行测定，都是应用气相色谱-质谱联用技术检测水果和蔬菜等农产品中上百种农药的多残留测定方法。     

超高效液相色谱-串联质谱同时测定茶叶中高氯酸盐和氯酸盐

建立了超高效液相色谱-串联质谱同时测定茶叶中高氯酸盐和氯酸盐的分析方法。选用ProElut C_(18)固相萃取柱对茶叶提取液进行净化、亲水性的Click Xion色谱柱分离,流动相A为水(含5 mmol·L~(-1)甲酸铵),流动相B为V_(甲醇)︰V_水=9︰1(含5 mmol·L~(-1)甲酸铵),甲酸调节pH至3.2,梯度洗脱分离,UPLC-MS/MS多反应监测(MRM)模式检测。该方法适用于茶叶中高氯酸盐和氯酸盐检测,平均回收率在60.5%~85.8%,RSD在4.9%~7.7%,高氯酸盐检出限为3mg·kg~(-1),氯酸盐检出限为5mg·kg~(-1)。方法操作简单、快速、灵敏度高,可以满足茶叶中高氯酸盐和氯酸盐的检测要求。     

不同沉淀剂对酚抽法提取植物蛋白质效果比较分析

酚抽法已经逐渐成为植物蛋白质组研究中通用的蛋白质提取方法,但在各种改进酚抽法中,应用到的沉淀试剂各不相同,致使蛋白沉淀得率、纯度和沉淀时间也各异,本研究以热带植物橡胶树叶片、胶乳和海马齿叶片为研究材料,在过饱和硫酸铵甲醇溶液、醋酸氨甲醇溶液和丙酮溶液沉淀剂下对比蛋白提取的效果,通过单向电泳检测、胶图质量分析、质谱鉴定、蛋白沉淀时间和得率比较,发现3种沉淀剂提取的蛋白样品1-DE图谱显示的蛋白条带数量均较多,但醋酸铵沉淀法提取蛋白图谱有条纹不清晰现象。得出结论：丙酮沉淀法对橡胶树叶片和胶乳蛋白质的提取率较高,硫酸铵沉淀法对海马齿叶片蛋白质提取率较高。过饱和硫酸铵甲醇溶液和丙酮沉淀剂提取的蛋白质质量较高,所得蛋白图谱背景清晰,质谱鉴定蛋白质信息量大。研究结果可优化提取高质量植物蛋白质的方法,并有望为顽拗类植物蛋白质组学研究提供参考。     

市售香蕉 15 种酚酸化合物含量的分析

为了探明香蕉中酚酸化合物的种类及含量,本研究采用超高效液相色谱串联质谱（UPLC-MS/MS）法对 香蕉果肉样品进行分析,并对色谱、质谱条件进行优化。结果表明,香蕉富含多种酚酸化合物,且酚酸化合物主 要以游离酯型和结合型存在。含量较高的 2 种酚酸为异阿魏酸（112.54~370.34 μg/g）、阿魏酸（83.96~157.54 μg/g）。 酚酸含量由高至低依次为异阿魏酸>阿魏酸>对香豆酸>3,5-二羟基苯甲酸>芥子酸>香草酸>咖啡酸>对羟基苯甲 酸>鞣花酸>丁香酸>反式肉桂酸>水杨酸。方法验证结果表明该方法检出限低、线性范围宽、灵敏度高,定量结 果准确、可靠,适用于实际样品检测;香蕉样品酚酸组分与含量检测结果可为香蕉的营养成分和功能活性物质 评价提供参考。     

猴耳环多酚的大孔树脂纯化工艺及其组分分析

建立并优化猴耳环多酚的纯化工艺并对其组分进行定性分析。本研究以猴耳环多酚粗提物为原料,以吸附及解吸附效果筛选了最优大孔树脂,再以吸附、解吸附和纯度为评价指标,考察各工艺参数对AB-8树脂纯化多酚的影响,最后采用超高效液相色谱-四级杆-飞行时间串联质谱（UPLC-Q-TOF-MS）法进行多酚组成定性分析。结果表明：优选 AB-8树脂,粗提物以质量浓度3 mg/mL、流速1 mL/min上样10 BV（柱体积：1 BV=10 mL）,水洗后,用60%乙醇5 BV以1 mL/min的流速洗脱。在此工艺条件下,多酚纯度达到58.64%。UPLC-Q-TOF-MS定性分析了纯化后猴耳环多酚14种组分。建立的猴耳环多酚的纯化工艺稳定可行,实现了其组分定性分析,为进一步研究提供了依据。     

Variation in polar lipid composition among near-isogenic wheat lines possessing different puroindoline haplotypes

The exact mechanism underlying wheat (Triticum aestivum L.) kernel hardness is unknown. Similar to puroindoline proteins, polar lipids are present on the surface of starch granules. The objective of this research was to determine the specific polar lipid species present on the surface of wheat starch from near-isogenic wheat lines that have different puroindoline haplotypes and endosperm hardness. Four near-isogenic wheat lines were used in this study, all derived from the soft cultivar Alpowa. Direct infusion tandem mass spectrometry was used to identify the lipid species in whole-meal, flour and starch samples. Endosperm hardness had no significant effect on the polar lipid contents in wheat whole-meal, a slight influence on the polar lipid contents of the flour fractions and a significant influence on the polar lipid composition of the polar lipids located on the surface of wheat starch. The greatest quantities of polar lipids on the starch-surface occurred when both puroindoline proteins were present in their wild-type form. Starch-surface polar lipid content dramatically decreased when one of the puroindoline proteins was null or if pin-B was in the mutated form. The least amount of polar lipids was present when pin-B was in its mutated form and pin-A was in its wild-type form.     

高效液相色谱串联质谱法定量检测稻谷中的稻曲病菌毒素A和D

 建立了稻谷中稻曲病菌毒素A和D污染物的高效液相色谱 串联质谱的分析方法。该方法简单、灵敏、准确,可同时定量检测稻谷中稻曲病菌毒素A和稻曲病菌毒素D。     

The Structure of the Lipid A of Gram-Negative Cold-Adapted Bacteria Isolated from Antarctic Environments

Gram-negative Antarctic bacteria adopt survival strategies to live and proliferate in an extremely cold environment. Unusual chemical modifications of the lipopolysaccharide (LPS) and the main component of their outer membrane are among the tricks adopted to allow the maintenance of an optimum membrane fluidity even at particularly low temperatures. In particular, the LPS’ glycolipid moiety, the lipid A, typically undergoes several structural modifications comprising desaturation of the acyl chains, reduction in their length and increase in their branching. The investigation of the structure of the lipid A from cold-adapted bacteria is, therefore, crucial to understand the mechanisms underlying the cold adaptation phenomenon. Here we describe the structural elucidation of the highly heterogenous lipid A from three psychrophiles isolated from Terra Nova Bay, Antarctica. All the lipid A structures have been determined by merging data that was attained from the compositional analysis with information from a matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry (MS) and MS² investigation. As lipid A is also involved in a structure-dependent elicitation of innate immune response in mammals, the structural characterization of lipid A from such extremophile bacteria is also of great interest from the perspective of drug synthesis and development inspired by natural sources.     

Vertical Distribution of Sodium in Roots of Rice Plants Exposed to Salinity as Analyzed by Cryo Time-of-Flight Secondary Ion Mass Spectrometry

Abstract

Distribution of Na⁺ along the root axis under salinity stress was analyzed in two rice (Oryza sativa L.) cultivars with different salt resistance (salt-sensitive IR 24 and salt-resistant Pokkali). Rice plants were grown hydroponically and NaCl was applied with nutrient solution at concentrations of 0, 25 and 50 mM for 7 d after germination. The distribution of Na⁺ in roots under salinity was analyzed by the cryo time-of-flight secondary ion mass spectrometry (cryo TOF-SIMS). The Na⁺ content in the root was higher in salt-sensitive IR 24 than in salt-resistant Pokkali under NaCl stress. The content was highest at the root tip and was decreased basipetally along the root axis. The difference in Na⁺ content between the cultivars was apparent in all regions from the root tip.     

Identification and quantitative determination of 2-acetyl-1-pyrroline using GC-TOF MS combined with HS and HS-SPME pretreatment

2-Acetyl-1-pyrroline (2-AP) was recognized as the key characteristic volatile in aromatic rice. In this paper, two precise and rapid methods for quantitative determination of 2-AP by headspace-gas chromatography-time-of-flight mass spectrometry (HS-GC-TOF MS) and headspace-solid phase micro-extraction-gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC-TOF MS) have been presented and compared. Chromatograms of 2-AP and internal standard (2-methyl-3-heptanone) in samples were extracted by accurate masses, and the response ratios of 2-AP to internal standard were used for constructing matrix-matched standard curve with the blanks deducted. Pretreatment conditions such as temperature and extractant amount were optimized. Linear ranges of two methods were 1–150 ng g⁻¹ with linear correlation coefficients (r) of 0.9998 and 0.9997, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) of HS-GC-TOF MS method were 0.68 ng g⁻¹ and 2.27 ng g⁻¹. LOD and LOQ of HS-SPME-GC-TOF MS method were 0.46 ng g⁻¹ and 1.50 ng g⁻¹, and could be reduced to 0.02 ng g⁻¹ and 0.06 ng g⁻¹, respectively, in the case of splitless mode. At spiking level of 100 ng g⁻¹, recoveries were 94.19–116.00% and 95.57–107.49% for HS-GC-TOF MS method and HS-SPME-GC-TOF MS method, respectively.     

基于衍生化GC-MS法分析不同栽培基质对铁皮石斛代谢的影响

栽培基质是影响铁皮石斛生长的主要因素之一,本研究拟选用松树皮(PB)、椰糠(CC)和松树皮:椰糠(PC,1:1)的复合基质栽培铁皮石斛,基于代谢组学思路探究栽培基质对铁皮石斛茎生长代谢的影响.通过环刀法测定3种基质的物理性质,利用苯酚-硫酸比色法测定铁皮石斛茎的多糖含量,采用硅烷化衍生化法结合气相色谱-质谱法检测铁皮石...