气相色谱/质谱法结合对大米中残留农药的分析

针对大米中痕量有机磷和氨基甲酸酯类农药,采用气相色谱质谱-选择离子检测法对目标物进行检测。试验以异丙基二硫醚作为内标物,分别建立2种目标物的GC-MS (SIM)分析标准曲线, 2种农药的定量线性范围分别为40～1 500μg/L及35～1 500μg/L。对液液萃取与快速溶剂萃取-固相萃取法进行对比,并通过正交试验优化样品制备条件等。结果表明,液液萃取法回收率72%～88%(加标浓度60～500μg/kg),但是操作复杂耗时;快速溶剂萃取-固相萃取法能够同时处理多个样品,对大米中异丙威和乙硫磷的最低检测限分别为27μg/kg及28μg/kg,精密度(RSD)为2.9%～4.5%,加标回收率为92%～103%(加标浓度60～500μg/kg)。快速溶剂萃取-固相萃取法的检测结果重现性好、检测限低,适用有条件的实验室选择使用。     

分散液相微萃取-液相色谱联用测定番茄中8种氨基甲酸酯农药残留

采用分散液相微萃取与液相色谱-荧光检测联用技术建立了测定番茄样品中氨基甲酸酯农药残留的新方法。对影响萃取和富集效率的因素进行了优化。萃取条件选定为在10mL带塞离心试管中加入5.0mL番茄样品溶液（ph7）,并快速注入2.2mL丙酮（分散剂2ml）/二氯甲烷（萃取剂200μL）混合溶液,振荡摇匀后以8000r/min离心5min,然后将上层清液吸干至试管底部萃取剂沉积相,用微量移液器准确移取100μL入自动进样瓶内胆进样分析。在优化的实验条件下,8种氨基甲酸酯农药的富集倍数可达20.4～24.3倍;检出限在8.0～20.0μg/kg（S/N=3：1）范围内。测定8种氨基甲酸酯农药残留的线性范围为50.0～500.0μg/kg,线性相关系数在0.9977～0.9998范围内。本方法已成功应用于番茄样品中8种氨基甲酸酯农药残留的测定,平均加标回收率在79.1%～98.6%范围内;相对标准偏差在3.5%～8.5之间,结果令人满意。     

离子液体分散液液微萃取氨基甲酸酯类农药

建立一种快速简便的超声辅助离子液体-分散液液微萃取(UA-IL-DLLEX)-高效液相色谱荧光法(HPLC-FD),分析蔬菜中速灭威、克百威、甲萘威、异丙威4种氨基甲酸酯类农药残留。考察系列影响萃取率的参数,包括萃取剂和分散剂的种类及其体积、样品p H、盐浓度、超声萃取时间。优化的萃取条件:200μL离子液体(IL,[C_6MIm][PF_6])为萃取剂,100μL四氢呋喃(THF)为分散剂,样品pH为7.0,不加盐,超声萃取5 min。在此条件下,方法的线性范围为0.02~1.0μg/m L,相关系数大于0.999,检出限(S/N=3)为0.006 3~0.018 mg/kg,3种阴性蔬菜中3个水平0.167,0.033和0.066 mg/kg的加标回收率为83.2%~110%,6次测定的相对标准偏差(RSD)为2.2%~5.1%。该方法应用于肇庆地区20种蔬菜中氨基甲酸酯类农药残留检测,所有蔬菜样品中均未检出速灭威、甲萘威和异丙威,6种蔬菜样品检出克百威浓度为0.017~0.22 mg/kg。     

悬浮固化-分散液-液微萃取-气相色谱法测定蔬菜中6种拟除虫菊酯类农药

建立了QuEChERS(Quick,Easy,Cheap,Effective,Rugged and Safe的缩写)结合悬浮固化-分散液-液微萃取(DLLME-SFO)-气相色谱测定蔬菜中6种菊酯类农药残留的方法。待测样品用含1%乙酸的乙腈溶液提取,提取液经混合固相分散萃取净化后经DLLME-SFO浓缩,最后用气相色谱(ECD)进行检测。实验考察了QuEChERS方法中提取溶剂的影响,DLLME-SFO中萃取剂种类与体积,分散剂种类和体积,盐浓度等对萃取效率的影响,优化结果为以40μL十六烷为萃取剂,1000μL乙腈为分散剂,5mL水中NaCl的加入量为1.25g。结果表明,在黄瓜和番茄基质中6种菊酯类农药在5、10、50μg/kg 3个添加水平下农药的平均回收率为84.84%~111.59%,相对标准偏差(RSD)为0.48%~9.61%,方法的检出限(LOD,S/N≥3)和定量限(LOQ,S/N≥10)分别为0.07~0.58μg/kg和0.22~1.94μg/kg。该方法快速、简便、灵敏、重复性好,可用于蔬菜中拟除虫菊酯类农药的快速筛查测定。     

微波辅助水蒸气法快速萃取西红柿中三嗪类农药残留

目的建立一种基于微波辅助水蒸气萃取结合液液分散微萃取用于西红柿中三嗪类农药残留的绿色萃取方法。方法西红柿样品经微波辅助水蒸气萃取后,用液液微萃取法对萃取液进行净化和富集,采用液相色谱-串联质谱法(LC-MS/MS)对三嗪类农药进行定性和定量分析。结果微波辅助水蒸气萃取结合液液微萃取法的最佳萃取条件为:微波功率为200 W,萃取剂为添加300μL乙腈的水蒸气,样品与石英砂比例为1:2,收集液体积为18mL;分散液液微萃取中的萃取剂为350μL的氯仿,分散剂为600μL的丙酮,并加入0.2 g NaCl以增加三嗪类农药的回收率。在最佳的萃取条件下,6种三嗪类农药在1、50和500μg/kg添加水平的回收率为62.1%~108.1%;日内和日间精密度分别在1.6%~6.7%和4.8%~10.3%之间(n=6),方法定量限为2μg/kg。结论该方法快速、准确、灵敏,适合测定西红柿中三嗪类农药残留。     

多壁碳纳米管分散固相萃取-液相色谱串联质谱法测定大米中26种氨基甲酸酯类农药及其代谢产物残留量

目的：建立多壁碳纳米管分散固相萃取-液相色谱串联质谱法测定大米中26种氨基甲酸酯类农药及其代谢产物残留量的分析方法。方法：大米样品水化后经酸化乙腈提取，多壁碳纳米管净化，C₁₈色谱柱分离，流动相采用2 mmol/L甲酸铵水和2 mmol/L甲酸铵甲醇进行梯度洗脱，电喷雾正离子(ESI⁺)模式电离，多反应监测模式检测，基质标准曲线外标法定量。结果：结果表明，26种农药在0.2～100 ng/mL范围内线性关系良好，相关系数均大于0.999，方法的检出限(S/N=3)为0.01～0.18μg/kg，定量限(S/N=10)为0.03～0.58μg/kg。在1、2μg/kg和20μg/kg 3个添加水平下，26种农药的回收率为87.4%～112.8%，相对标准偏差(n=6)为1.46%～7.22%。结论：该方法操作简便、灵敏度和精密度高、结果准确可靠，适用于大米中氨基甲酸酯类农药及其代谢产物残留量的检测。     

分散固相萃取-分散液液微萃取-气相色谱-质谱联用法测定中草药类保健食品中29种有机磷农药残留

目的建立测定中草药类保健食品中有机磷农药残留的分散固相萃取-分散液液微萃取-气相色谱-质谱联用法。方法样品经含0.5%甲酸的乙腈超声提取,上清液经含无水硫酸镁、N-丙基乙二胺(PSA)、C18的分散固相萃取管(d-SPE)净化后,采用分散液液微萃取(DLLME)步骤,用氯仿萃取、浓缩目标化合物。结果在最优条件下,线性范围为0.05~1.00μg/ml,线性相关系数在0.999以上,检出限(LOD)为0.3~3.0μg/kg,29种有机磷农药的平均加标回收率在70.3%~107.5%之间,相对标准偏差均10%。结论该方法具有简便快速、准确灵敏、萃取效率高等特点,可用于中草药类保健食品中有机磷农药残留的检测。     

微波辅助水蒸气萃取结合液液分散微萃取法萃取西红柿中三嗪类农药残留

目的 建立一种基于微波辅助水蒸气萃取结合液液分散微萃取用于西红柿中三嗪类农药残留的绿色萃取方法。方法 西红柿样品经微波辅助水蒸气萃取后,用液液微萃取法对萃取液进行净化和富集。之后采用液相色谱-串联质谱法对三嗪类农药进行定性和定量分析。结果 微波辅助水蒸气萃取结合液液微萃取的最佳萃取条件为：微波功率为200W,萃取剂为水蒸气并添加300μL乙腈,样品与石英砂比例为1:2,收集液体积为18mL;分散液液微萃取中的萃取剂为350μL的氯仿,分散剂为600μL的丙酮,并加入0.2gNaCl以增加三嗪类农药的回收率。在最佳的萃取条件下,6种三嗪类农药在1、50和500 μg/kg添加水平的回收率为62.1%~108.1%;日内和日间精密度分别在1.6% - 6.7%和4.8%- 10.3%之间(n=6), 方法定量限为2 μg/kg。结论 该方法快速、准确、灵敏, 适合测定西红柿中三嗪类农药残留。     

液相色谱-串联质谱法同时测定中草药保健食品中15种有机磷和氨基甲酸酯类农药残留

目的建立高效液相色谱-串联质谱法同时测定中草药保健食品中15种有机磷和氨基甲酸酯类农药残留。方法样品经乙腈提取后,高速离心,经分散型固相萃取小柱净化。采用Atlantis C_(18)(2.1 mm×100 mm,3μm)柱,以0.1%甲酸-乙腈为流动相,梯度洗脱分离。质谱采用正离子模式(electrospray ionization,ESI+),多反应监测模式(multiple reaction monitoring,MRM)进行检测,基质曲线外标法定量。结果该方法对15种农药残留的线性范围为0.001~0.1μg/mL,线性相关系数r≥0.993,加标回收率为82.7%~113.3%,相对标准偏差为2.7%~10.6%,检出限为0.8~24.6μg/kg。结论本方法操作简单、快捷,适用于中草药保健食品中15种有机磷和氨基甲酸酯类农药残留的同时检测,为保健食品质量控制提供依据。     

QuEChERS-高效液相色谱-串联质谱法测定牛奶中氨基甲酸酯类农药残留量

目的建立高效液相色谱-串联质谱法(high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS)测定牛奶中5种氨基甲酸酯类农药的方法。方法样品经乙腈提取、氮吹浓缩、QuEChERS净化,高效液相色谱-串联质谱法测定,采用外标法定量。结果5种氨基甲酸酯类农药在2.00-200μg/kg范围内线性关系良好(r>0.999);方法检出限为0.50~3.00μg/kg,定量限为1.50~10.00μg/kg;加标水平为0.010~0.050 mg/kg时,回收率为83.6%-108%,相对标准偏差为1.6%~15.6%。结论该方法简便快捷、灵敏度高,适用于牛奶中氨基甲酸酯类农药的检测。     

酶法水解麦胚制取持水剂的研究

采用响应面分析方法研究了酶法水解麦胚制取持水剂的生产工艺，并对产品应用于香肠中的抗氧化效果进行了试验。试验结果表明：酶法水解麦胚制取持水剂的优化工艺参数为：对１０％的麦胚乳４００ｍｌ，反应温度为４４．４℃，反应时间为４ｈ，酶与底物浓度比为８６０μ／ｇ。经优化工艺生产的持水剂的水分活度为０．８９６，所对应的水解度为２６．５％。应用于香肠可显著提高其货架寿命。     

Effect of treatment with non-alcoholic beverages of patients with gastritis and hyposecretion

A positive effect of use of non-alcoholic drink "Shirinskaia high-vitaminized treatment-board Water" in complex treatment of chronic gastritis with hyposecretion was revealed.     

遮盖山羊绒“亮丝”的媒介/活性染色工艺

针对变异山羊绒的"亮丝"现象,以及不同染料在羊绒纤维不同位置上染的差异性,采用酸性媒介染料和毛用活性染料复配染色。结果表明,与单一染料染色工艺相比,复配染色技术通过对关键染料和助剂的精准控制,优化染色工艺,覆盖"亮丝"的效果良好。染色产品和染色废液中的铬含量均符合相关标准。     

Decontamination of broilers with hydrogen peroxide stabilised with glycerol during processing

Experiments were conducted to assess the effects of different concentrations of hydrogen peroxide stabilised by glycerol solution in potable water on the bacteriological and organoleptic quality of freshly slaughtered broiler carcasses. Skin-pH and colour were measured 3.5 and 24 h after treatment and compared to untreated carcasses. Bacterial colonisation was determined 3.5 and 24 h and, 7 days after treatment, carcasses being stored at 1 degrees C. None of the concentrations used affected the appearance and "bloom" of the carcasses as could be measured by colorimeter and changing of the acidity. Mean microbial counts were significantly reduced (P<0.01) when treated and control broilers were compared. Average reductions of 0.3 up to1.4 log N for the mesophilic aerobic counts were achieved and from 0.4 up to 1.2 log N for Enterobacteriaceae. A 3% w/w solution made from a commercially available stock solution (Glyroxyl), which consists of 44% hydrogen peroxide, 44% demineralised water and 12% glycerol proved to lower colonisation more effectively than a 2% solution.     

Relationship of Physicochemical Characteristics with Sensory Profile of Cookies Enriched with Medicinal Herbs

In this work, a range of model cookies enriched with different quantities of medicinal herbs, applied in two forms (pulverized mixture and extract), were studied to compare and describe relationships between physicochemical and sensory data. Multivariate statistical methods were applied to estimate relationships in the analyzed data. Analysis of variance showed that the majority of analyzed parameters were highly significant in discriminating among the samples (p < 0.05), which supported the usefulness of their application in characterizing the quality profile of enriched cookies. Principal component analysis on physicochemical data revealed that cookies at the same enrichment level showed more similarities. Principal component analysis on sensory data exhibited a larger separation between the samples with increasing enrichment levels, especially in the case of pulverized herbal mixture. According to partial least squares regression, two significant partial least squares components explained 92.7% and predicted 78.0% variation in the data. The most important parameters in discriminating between the cookies enriched with medicinal herbs were lightness, red tonality, and hardness. The selected physicochemical parameters could be used in future studies to evaluate variously enriched cookies by establishing models and investigating the predictability of sensory quality.     

酸解-酶膜联用法检测谷氨酰胺

研究了谷氨酰胺在酸性条件下的水解特性后 ,建立了酸解 酶膜联用的谷氨酰胺定量分析方法。此方法的线性范围为 10～ 40mmol/L ,相关系数R =0 .999,分析误差为 0 .1mmol/L ,测量所需时间约为 30min。     

猪皮制革必须适应市场经济

本文讨论了猪皮制革的现状,分析其成因,在此基础上阐明了猪皮制革必须适应市场经济的观点,并提出了猪皮制革走出低谷的若干具体对策。     

Synthesis of 2-Deoxy-maltooligosaccharides with Phosphorylase and Their Degradation with Amylases

By reaction of phosphorylase with D-glucal and inorganic phosphate instead of the natural substrate α-D-glucosyl phosphate novel 2-deoxy-maltooligosaccharides could be synthesized. Their properties and characterization by NMR spectroscopy, mass spectrometry and HPLC are described. Under similar conditions, except a higher phosphate concentration, 2-deoxy-α-D-glucosyl phosphate is obtained. This can also serve for the enzymatic elongation of the primer with 2-deoxy-glucosyl residues. The unnatural 2-deoxy-maltooligomers could be applied successfully as substrates for the exo-cleaving enzymes glucoamylase and β-amylase.     

强度为Weibul分布,应力为其他分布的可靠度求解

运用应力—强度相干理论,推导出强度为Ｗｅｉｂｕｌ分布,应力为其他分布时可靠度求解表达式,并应用专用数学软件Ｍａｔｈｅｍａｔｉｃａ实现了数值的求解。文中给出若干求解实例,求解的过程简便、直观,有利于工程可靠性设计与分析借鉴     

压力棒隔距块在纺细号纱上的应用

介绍了前区压力棒隔距块的结构和作用原理,探讨了压力棒隔距块在纺细号纱上的应用及工艺配置和技术要点;对比试验表明细纱前区加压力棒隔距块后,加强了对纤维的控制,有利于成纱质量的改善,尤其在细号纱上作用明显,但也要注意上车工艺一致性的调整,同时加强操作管理,否则会影响成纱条干的CVb值和纱疵数量.