PRiME HLB前处理技术联合超高效液相色谱-三重四极杆质谱系统检测水产品中17种磺胺类药物残留

使用通过型固相萃取小柱PRi ME HLB处理水产品样品,建立了一种水产品中17种磺胺类药物的简单、快速的筛选分析方法。水产品样品经80%乙腈水溶液(含0.2%甲酸)提取,过PRi ME HLB固相萃取柱净化,浓缩后经C_(18)色谱柱梯度洗脱分离,超高效液相色谱-三重四极杆质谱系统进行定量分析。结果表明,17种磺胺类药物在1.0~50.0 ng·mL^(-1)线性关系良好,相关系数R^(2)>0.99;该方法检出限为2μg·kg^(-1);添加浓度为10μg·kg^(-1)时方法回收率在71.3%~118.4%,RSD值均小于20%。

Epidemic Regularity and Control Effect of Huanglongbing (HLB) in Different Management Approaches

In order to reveal the epidemic regularity of Huanglongbing （HLB） in different management approaches, different citrus production areas were selected between 2002 and 2012 to compare epidemic regularity of different types and control effects of different management approaches with plant incidence rate. All survey data in 11 years were used to build a mathematical model, and epidemic evolution and control effects were quantitatively analyzed. The results indicated that diffusion and prevalence of HLB generally increased linearly. In naturally growing citrus orchards without artificial control, the annual diseased plant rate was 11.11%, and the epidemic diffusion model was y1 = 12. 24x - 1.382 8 （ n =9, r =0. 976 9 ＊ ＊ ）. Under general prevention and control conditions, the annual diseased plant rate was 4.69%, the epidemic diffusion model was Y2 = 5. 449 8x - 1.603 5 （ n = 11, r =0. 974 9 ＊ ＊ ）, and the control effect was 43.93% （22.93% - 55.04% ）. In citrus orchards with integrated prevention and control, the epidemic diffusion model was Y3 = 0. 366 3x - 0. 342 2 （ n = 11, r = 0. 989 8 ＊ ＊ ）, the control effect was 96.15% （94.95% -97.40% ）, and the annual diseased plant rate was 0.31%. Thus, HLB is preventable and controllable as long as integrated prevention and control work is implemented well.

PRiME HLB固相萃取-超高效液相色谱-串联质谱法测定水产品中的孔雀石绿含量

目的:建立了水产品中显色孔雀石绿(MG)及隐色孔雀石绿(LMG)残留量的超高效液相色谱-串联质谱测定方法。方法:样品用1.5%甲酸乙腈提取,离心,提取液经过PRiME HLB通过式固相萃取柱净化,氮吹后复溶,UPLC-MS/MS测定,同位素内标法定量。结果:在浓度为0.5~10.0μg/L范围内线性关系均良好,相关系数均大于0.995,检测限为0.008~0.01μg/kg,定量限为0.02~0.04μg/kg,加标回收率为86.8%~110.5%,相对标准偏差为1.6%~5.8%。结论:该方法高效快捷、准确可靠,能够满足大批量水产品中孔雀石绿及隐色孔雀石绿的检测。

HLB固相萃取小柱应用于液相色谱-串联质谱法 测定兽药残留的性能研究

以国标GB 31658.17—2021《食品安全国家标准动物性食品中四环素类、磺胺类和喹诺酮类药物残留量的测定液相色谱-串联质谱法》为前处理方法,采用几种不同类型萃取柱进行样品加标回收试验,以液相色谱-串联质谱法对猪肉中的四环素类、磺胺类和喹诺酮类药物进行测定,外标法定量。结果表明,对于7种药物回收率最高的为单体比例为13/8的自制HLB萃取柱,3种不同添加质量浓度(10,20,50 ng/mL)的回收率为62.2%~101.4%,相对标准偏差(RSD)均小于7%,且高于其他商品化HLB萃取柱。研究表明,自制HLB固相萃取柱相较于其他商品柱有更好的性能,可以作为商品HLB小柱的替代品。

Curent Situation of “Candidatus Liberibacter asiaticus” in Guangdong,China,Where Citrus Huanglongbing Was First Described

Citrus Huanglongbing （HLB,yellow shoot disease） was first observed in the coastal Chaoshan Plain of Guangdong Province,China,in the late 19th century based on descriptions of yellow shoot symptoms. “Candidatus Liberibacter asiaticus”has been considered as a putative pathogen associated with HLB since 1994.Information about the curent prevalence of this bacterium is important for HLB control in Guangdong and also provides useful reference for HLB study elsewhere.In 2007,we collected HLB symptomatic citrus samples from 16 cultivars in 12 prefecture cities,mostly in the north and west regions of Guangdong,where major citrus fruits are currently produced.Among the 359 samples collected,241 （67.1%） were positive for “Ca.L.asiaticus”,distributed in 15 out of the 16 cultivars from all 12 cities,indicating the widespread prevalence of “Ca.L.asiaticus” in Guangdong Province.The detection rates varied from 16.7 to 100% depending on location and cultivar.Lower detection rates were found in newer citrus cultivation cities among the previously less popular but now promoted cultivars.In reviewing the citrus management and pest control practice,we believe that infected nursery stocks play a key role in the current spread of “Ca.L.asiaticus”.

Threshold Dynamics of a Vector-Borne Epidemic Model for Huanglongbing with Impulsive Control

In this paper, the basic reproduction number is calculated for Huanglongbing (HLB) model with impulses which is a vector-borne epidemic model with impulses. For controlling HLB, farmers’ experience is replanting of healthy plants and removing infected plants. To reflect the real world, we construct an impulsive control model which considers replanting of healthy plants and removing infected plants at one fixed time. By analyzing the model, we conclude that the disease-free equilibrium is globally asymptotically stable if the basic reproduction number Ro 1, and we prove that the HLB is permanence if the basic reproduction number Ro > 1.

Digital Gene Expression Analysis of Huanglongbing Affected Mandarins(Citrus reticulata Blanco)In Response to Thermotherapy

Huanglongbing(HLB),which is mainly associated with“Candidatus Liberibacter asiaticus”(CLas),is currently threatening citrus production around the world.This destructive century-old disease results in callose deposition in phloem plasmodesmata and starch overaccumulation in leaf chloroplasts.Heat treatment with high humidity has proven to be effective in eliminating the CLas titers in potted citrus trees.This study explored the curative mechanisms and impact of heat treatment(from 32 to 48°C with 75%±5%relative humidity,14h in light and 10h in dark for four days)on mandarin trees(Citrus reticulata Blanco)that were severely infected by CLas using Solexa/Illumina’s digital gene expression(DGE)profiling.A total of 838 differentially expressed genes(DEGs)were identified,of which 510 were downregulated.Proteinprotein interaction analysis of the DEGs indicated that the thermotherapy of HLB trees downregulated the circadian clock related genes in chloroplasts and upregulated the RNA-editing process in the mitochondria,characterized by 141 genes encoding pentatricopeptide repeatcontaining proteins(PPR)being all upregulated.Furthermore,the expression of phenylpropanoid and flavonoid biosynthesis genes,and auxininduced genes were suppressed.The defense response pathway of the thermotherapy treated diseased trees was apparently disrupted,as indicated by the downregulation of LRR receptor-like serine/threonine-protein kinase FLS2 gene.This study improves our understanding of the curative mechanisms of heat treatment on HLB trees and CLas biological regulation.Importantly,this provides new insights on the involvement of RNA modification by PPR genes and changes in the circadian clock after the heat stress treatment of CLas-infected citrus.

Beneficial horticultural responses from the application of solar thermotherapy to mature Huanglongbing-affected citrus trees

The detrimental effects of Huanglongbing(HLB)on citrus are well known and so is the need for effective methods to combat this disease.Solar thermotherapy(ST),one of the management methods to help alleviate some of the negative effects of HLB,is the process of heating trees to therapeutic temperatures by encompassing the tree within a plastic structure(Visqueen)to harness the sun’s natural energy.ST was applied to mature‘Valencia’citrus trees in three locations.Tree vigor,yield,and Candidatus Liberibacter asiaticus(Las)titer in leaves were monitored for two consecutive seasons post ST treatment,while fruit and juice quality were evaluated at the end of the second season.ST promoted an increase in canopy density in most groves tested and did not have a significant effect on fruit quantity,despite the prolonged exposure of the trees to increased temperatures.Moreover,Las titer was reduced in both leaves and juice processed from affected trees post ST.With respect to fruit quality,the ratio of total soluble solids to titratable acidity was higher post ST compared to controls as was the sucrose content of the juice in most treated groves,whereas limonin was higher in juice from control trees.Principal components analysis of aroma volatiles showed significant differences between juice from treated versus control trees with volatiles imparting top-note and freshness to orange juice,such as acetaldehyde,hexanal,Z-3-hexenol and linalool,being higher in juice fromtreated trees.Taste panels confirmed that flavor differences existed,ultimately showing that ST resulted in improved juice flavor in well-managed groves.Although the effects of ST on the trees appear temporary,such outcomes emphasize its utility when used as part of an integrated management strategy for HLB-affected citrus,imparting beneficial horticultural responses with minimal to positive effects on subsequent juice flavor.

不同HLB值的表面活性剂对LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)的影响

表面活性剂在材料制备中具有控制形貌和改善性能的重要作用,本工作试图建立一种表面活性剂的亲水亲脂平衡(HLB)值与材料之间的关系。采用水热法制备LiNi_(0.8)Co_(0.1)Mn_(0.1)(OH)_(2)选用不同HLB数的表面活性剂诱导和控制正极材料的形貌,获得优异的性能。为了改性三元层状材料,分别使用不同HLB值的脱水山梨糖醇单硬脂酸酯(Span60)、十二烷基苯磺酸钠(SDBS)、十六烷基三甲基溴化铵(CTAB)和十二烷基硫酸钠(SDS)作为表面活性剂。四组材料的首次放电比容量分别为184.1 mAh/g、199.4 mAh/g、179.1 mAh/g和139.1 mAh/g。

Global Dynamics of a New Huanglongbing Transmission Model with Quarantine Measures

An epidemic model which describes Huanglongbing transmission is proposed with the goal of investigating the effect of quarantine measures on the spread of diseases. First of all, the analytical formula for the basic reproduction number R0 is obtained by the means of next generation matrix, and the existence of disease-free equilibrium and endemic equilibrium is discussed. Then, the local stability and the global stability of equilibria are investigated by using Routh-Hurwitz criterion and Lyapunov function, respectively. Numerical simulations indicate that comprehensive quarantine measures can effectively control the spread of Huanglongbing. It provides a reliable tactic basis for preventing the epidemic outbreak.

Effects of Nutrients on Growth and Yield of Shatian Pomelo Trees with Huanglongbing

[Objectives]In order to effectively alleviate Huanglongbing of Shatian pomelo trees,a nutrient preparation was developed and its effect on the growth and yield of Shatian pomelo was explored.[Methods]A field experiment was carried out with four treatments:control group,nutrient solution group,agent group,and nutrient solution+agent group,and the liquids were infused into the fruit trees through the trunk using a hanging bag.[Results]Through field trials,it was found that the nutrient solution treatment of fruit trees significantly increased the leaf chlorophyll content and nitrogen content,which increased by 17%and 12%compared with the control group,respectively,reaching(70.80±1.57)and(5.53±0.1)mg/kg,respectively;and the combined application of the nutrient solution and powder agents greatly alleviated the symptoms of Huanglongbing in Shatian pomelo plants,and significantly improved the bacterial disease index,photosynthetic intensity and yield,which increased by 152%,158%and 213.53%respectively,reaching(371.00±7.22),(406.67±7.09)and 23.15 kg/hm^2.[Conclusions]The use of the nutrient solution and agents greatly alleviated the symptoms of Huanglongbing of Shatian pomelo plants,and significantly improved the chlorophyll content,nitrogen content,bacterial disease index and photosynthetic intensity.Meanwhile,the number of fruit per plant and the weight of single fruit were better than other treatment groups and the control group,the technical operation was simple and the effect was obvious.This provides a certain reference basis for the prevention and control measures of Huanglongbing in Shatian pomelo plants.

Prevention and Control Measures of Citrus Huanglongbing and Application Ideas of Repellent Plants

Citrus huanglongbing is the most infectious and destructive disease in citrus production in the world.The essential characteristics,transmission routes and severity,and diagnosis of citrus huanglongbing,as well as control methods and effects of Diaphorina citri are summarized,and the application ideas of repellent plants is put forward.

Field Identification and Prevention and Control Techniques of Citrus Huanglongbing of Orah Mandarin

In order to promote the development of Orah mandarin industry in Guangxi and reduce the harm of citrus huanglongbing to Orah mandarin,the pathogen,characteristics,occurrence regularity and field symptoms of citrus huanglongbing were summarized,and scientific prevention and control measures were put forward,such as strict implementation of quarantine system,cultivation and use of disease-free seedlings,strengthening field management,timely control of psyllid,timely removal of diseased trees,etc.

A Rapid Identification Method for Germplasm Materials Resistant to Citrus Huanglongbing Disease

[Objectives]This study was conducted to develop a rapid identification method for citrus germline materials resistant to Huanglongbing disease and lay a basis for accelerating citrus breeding for resistance to Huanglongbing and increasing the breeding efficiency.[Methods]Thirty-six citrus germplasms suspected to be resistant to citrus Huanglongbing disease were collected.The method of direct high grafting to citrus trees infected with Huanglongbing pathogen was adopted.The resistance of the test materials was identified and evaluated by field symptoms combined with quantitative PCR.It was defined as the top grafting identification method.[Results]The test materials that were grafted in spring started to germinate after one month,and three months late(June 5,2018)typical mottled yellowing on leaves was observed on KH-14 for the first time.After four months(July 5,2018)of top grafting,typical mottled yellowing occurred on 23 materials,and 11 materials showed no such symptom.After six months(September 4,2018)of top grafting,although the growth of KH-18,KH-12,KHY-4,KHY-5 and KHY-6 were normal,yellowing was observed on their leaves.Only KH-21 grew well,and showed no yellow shoots and yellowing leaves.It was identified as the material with resistance to Huanglongbing disease.Quantitative PCR tests on the above six materials showed that KH-21 was negative and other five were positive.Real-time fluorescence quantitative PCR test indicated that the average Huanglongbing bacteria amount in KH-21 was 1870.0 cell/μg DNA,and the average Huanglongbing bacteria amount in the control material was 372285.5 cell/μg DNA,indicating KH-21 was resistant to Huanglongbing bacteria.[Conclusions]The method for infecting bacteria by top grafting takes six months,can detect large amount of seedlings,and is time-saving,efficient,cost-saving and accurate.This method can quickly identify the resistance of citrus varieties to citrus Huanglongbing disease,and can be popularized and used in the identification of citrus Huanglongbing disease resistance.

P RIME HLB前处理/高效液相色谱-串联质谱法测定鸡蛋中氟虫腈及其代谢物

建立了鸡蛋中氟虫腈及其代谢物残留的液相色谱/串联质谱检测方法分析方法。样品经乙腈提取,PRIME HLB净化脂肪,采用电喷雾离子源负离子检测模式(ESI-)和多重反应监测(MRM)模式测定,外标法定量分析。结果表明:氟虫腈及其代谢物在0.1~20 ng/mL的范围内均具有良好的线性关系,相关系数(R2)不小于0.9997,在2、10和20μg/kg不同加标浓度下的平均加标回收率为99.92%~108.3%,相对标准偏差:1.96%~5.01%,方法检出限为0.008~0.023μg/kg。该方法快速、简便、灵敏,适用于鸡蛋中氟虫腈及其代谢物的快速测定。

PRiME HLB固相萃取-高效液相色谱-串联质谱法测定化妆品中的双酚A

建立了PRiME HLB固相萃取-高效液相色谱-串联质谱测定水状、膏霜状和精油状化妆品中的双酚A残留量的方法。化妆品基质采用5%氨水乙腈溶液提取,使用PRiME HLB固相萃取柱净化后,以Waters ACQUITY UPLC BEH C18(100 mm×Φ2.0 mm, 1.7μm)为色谱柱,甲醇-0.1%氟化铵水溶液为流动相,梯度洗脱。电喷雾离子源负离子扫描模式,多反应监测(MRM)进行检测。结果表明,双酚A在本方法下响应较好,在2~50 ng/mL范围内线性良好,相关系数大于0.99,各基质的平均加标回收率为92.5%~101.2%,相对标准偏差小于3.2%。该方法前处理快捷简便,定量准确可靠,能很好地检测化妆品中双酚A的残留量。

长春花感染柑橘黄龙病菌微波热处理防控效果

为探索黄龙病防治途径,开展微波热处理对黄龙病的防控效果研究。该研究搭建了微波热处理平台,对长春花微波热处理参数(转盘转速、单个磁控管的微波功率、磁控管数量)进行优化,并用优化后的参数组合对感病长春花进行热处理,处理后90 d内跟踪检测长春花叶片中黄龙病菌的浓度、淀粉和类黄酮的含量。结果表明,长春花微波热处理的最优参数组合为单个磁控管的微波功率150 W、3个磁控管、转速15 r/min;热处理90 d后,感病长春花叶片中的黄龙病菌Ct值(阈值循环数,该值低于32时为阳性)由阳性(17.01±0.97)转至近阴性(31.91±2.35),病菌浓度下降了99.98%,淀粉含量和类黄酮含量恢复至正常水平,植株的活性恢复较好。研究表明,微波热处理有效抑制植物体内的黄龙病菌,可为黄龙病的规模化防治提供新思路。

多粘类芽孢杆菌发酵液对脐橙果树内生菌的抑菌研究

目的:验证一种多粘芽孢杆菌发酵液对脐橙果树内生菌抑制特性,为筛选治理黄龙病的药物奠定基础。方法:纯化培养黄龙病果树内生菌,经16S rDNA鉴定菌属,选择和黄龙病菌有相关性的内生菌为药敏实验菌株,以青霉素G、四环素、利福平、链霉素、吡哌酸、氨苄西林和多粘类芽孢杆菌发酵液为对比抑菌药物,分析抑菌差异以便筛选合适的内生菌抑菌药物。结果:分离获得黄龙病菌的相关性内生菌6株,药敏实验发现链霉素对所有菌株无药敏,青霉素G、利福平、氨苄西林对细杆菌属具有高药敏性,四环素对代尔夫特菌属和不动杆菌属具有高药敏性,发酵液对代尔夫特菌属和伯克霍尔德菌属具有高的药敏性,其中,利福平对所有菌株均有药敏性,四环素仅对伯克霍尔德菌属无药敏性。结论:多粘类芽孢杆菌发酵液对黄龙病果树内生菌有优良的抑制效果。

界面结构和HLB乳化规则(Ⅰ)界面模型与稳定机理

以白油为乳化对象 ,TX,AEO系列表面活性剂为乳化剂 ,在不同的乳化剂配比 ( HLB值 )和用量下 ,考察各乳液体系的稳定特性 ,并把实验所覆盖的 HLB范围划分为 5个区域 ,采用多吸附层模型分析了各 HLB区油水界面吸附层结构特点及对乳液絮凝和聚并过程的影响 ,从而说明了 HLB规则在本实验体系中起作用的物理机制。

乳化剂的HLB值对搅打稀奶油搅打性能的机理研究

重点研究了乳化剂的HLB值对搅打稀奶油的脂肪部分附聚率与搅打性能之间的关系.结果表明:高HLB值乳化剂在促进脂肪球的部分附聚的能力比低HLB值乳化剂强.HLB值低于6时,则部分附聚速度缓慢且部分附聚率低于50%,形成的泡沫结构稳定性差;乳化剂的HLB值在6～8之间,部分附聚速度适中,能够获得60%左右的脂肪部分附聚率和形成较理想的泡沫结构; HLB值大于9时,部分附聚速度过快且部分附聚率高于80%,形成的泡沫结构粗糙且稳定性差.