QuEChERS前处理结合气相色谱电子捕获检测器检测果蔬中30种农药残留

目的 应用QuEchERS前处理法处理样品,建立了气相色谱-电子捕获检测器检测多种水果蔬菜中30种常见农药残留的分析方法。方法 用乙腈作为溶剂,分别采用无缓冲盐体系、醋酸缓冲盐体系和柠檬酸盐缓冲体系提取对蔬果中30种农药进行提取,用PSA进行净化后上机处理。结果 采用不加缓冲盐体系提取,经PSA净化的方法适用于本文所选30种农药的检测,将该方法用于黄瓜、西红柿、生菜、苔菜、包菜、胡萝卜、梨、草梅,苹果等蔬果中30种农残的检测,结果表明30种农药残留的回收率在75%-122%之间,相对标准偏差在1%-12%之间;结论 该方法准确、简单、快速、灵敏度高,可以满足日常农残快速筛选的检测要求。     

QuEChERS-液相串联质谱法快速测定蔬菜水果中氟吗啉和烯酰吗啉残留量

目的建立基于QuEChERS与液相串联质谱(liquidchromatographytandemmassspectrometry,LC-MS/MS)联用技术快速测定蔬菜水果中氟吗啉和烯酰吗啉残留量的分析方法。方法样品经乙腈提取后,用QuEChERS法净化, Symmetry C18色谱柱分离, LC-MS/MS外标法定量。结果方法学验证,该方法具有较高的灵敏度,氟吗啉和烯酰吗啉的检出限为0.05μg/kg,定量限为0.1μg/kg;在0.1～25μg/kg浓度范围,线性相关系数大于等于0.9963,回收率在82.4%～106.3%之间,相对标准偏差为1.5%～8.8%,该方法具有较好的回收率和良好的再现性,满足国家相关标准要求。结论该方法处理过程快速简便,灵敏度高、专属性强。     

混合辐照饲料喂养大鼠的骨髓多色性红细胞微核细胞率观察

本文用两组辐照饲料对Wistar大鼠进行了110天和150天喂养,观察其骨髓多色性红细胞(PCE)的微核效应。一组为混合辐照饲料组,辐照饲料占80％;另一组为辐照蔬菜组,辐照蔬菜占总饲料的3％,辐照剂量为2KGy,是实际需要的辐照剂量2倍以上。同时设有普通饲料的阴性对照组,和用环磷酰胺处理或给以全身整体照射的阳性对照组。微核测定采用Giemsa染色法、Harris苏本精复染法和荧光染色法,两批实验均表明,在本实验条件下,不论是喂养混合辐照饲料还是辐照蔬菜,都未见到大鼠骨髓PCE微核细胞率有所增高。     

高效液相色谱法同时测定蔬菜中多种磺酰脲类除草剂的残留量

建立高效液相色谱法同时测定蔬菜中8种磺酰脲类除草剂残留量的检测方法。样品经乙腈提取、凝胶渗透色谱净化、C18固相萃取柱净化后,采用高效液相色谱分离,二极管阵列检测器检测,外标法定量。本法简便、快速、定量准确、精密度高,适用于进出口蔬菜中多种磺酰脲类除草剂残留量的同时检测。     

Effects of Different Treatments on the Inactivation of Various Seedborne Viruses in Some Vegetables

In this study, we considered the efficacy of seed treatments for the inactivation of some seedborne viruses in tomato, pepper, melon, squash, bean and lettuce seeds, which are essential for human nutrition and seed production in our country. A total of 325 seed samples obtained from various farmers and foundations were tested by DAS-ELISA and RT-PCR procedures. Eight seed lots infected with Tomato mosaic tobamovirus (ToMV), Tobacco mosaic tobamovirus (TMV), Cucumber mosaic cucumovirus (CMV), Soybean mosaic potyvirus (SMV) and Lettuce mosaic potyvirus (LMV) were selected as research materials. Virus inactivation treatments were made by using acetic acid (CH₃COOH), hydrogen peroxide (H₂O₂), hydrochloric acid (HCl), sodium hypochlorite (NaClO), Triton X 100, dry heat, heated water, ozone (O₃), and UV (305 nm wavelength). The most effective treatments for reducing virus concentration were HCl, heated water (65 °C) and ozone (10 g m^?3). These treatments reduced concentrations of seed-borne viruses in ranges of 51%, 42%, and 32%, respectively. Other treatments were less effective and reduced virus concentrations in the range of 27%–12%. HCl and ozone treatments were the most effective and applicable methods because they did not have negative effect on seed germination.     

气相色谱内标法测定蔬菜中的乐果

目前,测定蔬菜中乐果农残主要使用外标法,仪器的重现性差,相对偏差达到10％左右,造成定量分析误差较大.产生重现性差的原因是PFD检测器测定乐果时信号的响应值有不断地增大的趋势,本文采用三唑磷为内标物,对仪器条件和处理方法进行了优化,较好地改善了测定方法的重现性,并且简化了处理方法,使样品前处理具有较好的可操作性和稳定性,方法的加标回收率达到92.2～105.0％.     

新型果蔬切丁机的设计

国内现有切丁机存在着结构复杂、生产效率低、切出10mm以上果蔬大丁形状不规整的问题,无法满足国内果蔬加工业的发展需求。提出采用离心切削法进行果蔬切片、圆盘刀切丝、横切刀切丁的三维切丁技术的新型果蔬切丁机方案。通过对果蔬的切丁成型分析,得到切10mm以上果蔬大丁形状不规整的原因。仿真分析得到切丁机推进器和横切刀之间的速比以及两者之间的中心位置布置的合理组合。对切丁机主要结构部件进行了设计,研制果蔬切丁机样机。性能试验表明:切出的(15×15×15)mm和(20×20×20)mm马铃薯立方块形状规整,其相对百分数均小于15%,达到了设计要求。     

Health risk from heavy metals via consumption of food crops in the vicinity of Dabaoshan mine, South China

Heavy metal contamination of soils resulting from mining and smelting is causing major concern due to the potential risk involved. This study was designed to investigate the heavy metal (Cu, Zn, Pb and Cd) concentrations in soils and food crops and estimate the potential health risks of metals to humans via consumption of polluted food crops grown at four villages around the Dabaoshan mine, South China. The heavy metal concentrations in paddy and garden soils exceeded the maximum allowable concentrations for Chinese agricultural soil. The paddy soil at Fandong village was heavily contaminated with Cu (703 mg kg^− 1), Zn (1100 mg kg^− 1), Pb (386 mg kg^− 1) and Cd (5.5 mg kg^− 1). Rice tended to accumulated higher Cd and Pb concentration in grain parts. The concentrations of Cd, Pb and Zn in vegetables exceeded the maximum permissible concentration in China. Taro grown at the four sampled villages accumulated high concentrations of Zn, Pb and Cd. Bio-accumulation factors for heavy metals in different vegetables showed a trend in the order: Cd > Zn > Cu > Pb. Bio-accumulation factors of heavy metals were significantly higher for leafy than for non-leafy vegetable. The target hazard quotient (THQ) of rice at four sites varied from 0.66-0.89 for Cu, 0.48-0.60 for Zn, 1.43-1.99 for Pb, and 2.61-6.25 for Cd. Estimated daily intake (EDI) and THQs for Cd and Pb of rice and vegetables exceeded the FAO/WHO permissible limit. Heavy metal contamination of food crops grown around the mine posed a great health risk to the local population through consumption of rice and vegetables.     

Heavy metal contamination of water, soil and produce within riverine communities of the Río Pilcomayo basin, Bolivia

The Río Pilcomayo heads on the Cerro Rico de Potosí precious metal-polymetallic tin deposits of Southern Bolivia. Mining of the Potosí deposits began in 1545 and has led to the severe contamination of the Pilcomayo's water and sediments for at least 200 km downstream of the mines. This investigation addresses the potential human health affects of metal and As contamination on four communities located along the upper Río Pilcomayo by examining the potential significance of human exposure pathways associated with soils, crops and water (including river, irrigation and drinking water supplies). The most significantly contaminated agricultural soils occur upstream at Mondragón where Cd, Pb and Zn concentrations exceed recommended guideline values for agricultural use. Further downstream the degree of contamination decreases, and metal concentrations are below Dutch, German and Canadian guideline values. Metal and As concentrations in agricultural products from the four communities were generally below existing guidelines for heavy metal content in commercially-sold vegetables. Thus, the consumption of contaminated produce does not appear to represent a significant exposure pathway. A possible exception is Pb in carrots, lettuce and beetroots from Sotomayor and Tuero Chico; 37% and 55% of the samples, respectively, exceeded recommended guidelines. Most communities obtain drinking water from sources other than the Río Pilcomayo. In general, dissolved concentrations of metals and As in drinking water from the four studied communities are below the WHO guideline values with the exception of Sb, which was high at Tasapampa. The inadvertent ingestion of contaminated water from irrigation canals and the Río Pilcomayo represents a potential exposure pathway, but its significance is thought to be minimal. Given the degree of soil contamination in the area, perhaps the most significant exposure pathway is the ingestion of contaminated soil particles, particularly particles attached to, and consumed with vegetables. The risks associated with this pathway can be reduced by thoroughly washing or peeling the vegetables prior to consumption. Other exposure pathways that are currently under investigation include the consumption of contaminated meat from livestock and poultry, which drink polluted waters and the ingestion of contaminated wind-blown dust.     

Evaluation of Zataria multiflora Boiss. essential oil activity against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes by propidium monoazide quantitative PCR in vegetables

Essential oils (EOs) have long been applied as flavoring agents in foods, and due to their content in antimicrobial compounds, they have potential as natural agents for food preservation. Recently, real-time PCR in combination with PMA has successfully been applied to discriminate between live Escherichia coli O157:H7 and dead bacteria killed by cumin, clove, oregano and cinnamon EOs. In this study, initial experiments were performed in order to elucidate the minimum bactericidal concentration of Zataria multiflora EOs on E. coli O157:H7, Salmonella enterica and Listeria monocytogenes. Thereafter PMA-qPCR was applied in order to selectively quantify life cells within a bacterial population treated with Z. multiflora EO. Inactivation was obtained at EO concentrations of 0.02, 0.035, 0.045 for L. monocytogenes, E. coli O157:H7 and S. enterica, respectively. L. monocytogenes were totally killed in 30 min while it took 1 h 30 min for the gram negative pathogens. As a conclusion Z. multiflora EO has potential as natural food additive or biopreservative since it was able to irreversibly inactivate the three pathogens tested, at lower concentrations than other EOs and short exposition times. In addition, the PMA-qPCR approach proved efficient to selectively detect live pathogenic bacteria in vegetables following inactivation with Z. multiflora EO.