Removal of methyl orange from aqueous solution by Azolla filicoloides:Synthesis of Fe_3O_4 nano-particles and its surface modification by the extracted pectin of Azolla

The modified Fe₃O₄ nano-particles with the extracted pectin from the cell wall of Azolla filicoloides（FN-EP） can remove methyl orange as a water-soluble azo dye from waste water better than Azolla and the extracted pectin from Azolla（EPA）,alone.It could be due to more crowding the main functional groups of uptake after binding pectin with nano-particles.Thermodynamic studies showed that adsorption equilibrium constant（K_L） and maximum adsorption capacities(Q_max) were increased with decreasing temperature（exothermic）.The maximum uptake capacity(Q_max) of dye by FN-EP in a batch reactor was 0.533,0.498 and 0.446 mmol/g at 5,25 and 50℃,respectively.The enthalpy change（△H） and entropy change（△S） were -15.31 kJ/mol and -0.02434 kJ/mol K,respectively.     

高光谱成像的多种类柑橘病虫药害叶片检测方法研究

影响柑橘生长的病虫药害种类繁多,目前的检测方法大多针对单一病症,开发基于高光谱成像和机器学习的多种类柑橘病虫药害叶片快速精准检测方法,对果园精准施药和柑橘产业健康发展具有重要意义。以果园自然发病的柑橘叶片为研究对象,包括柑橘正常叶(50片)、溃疡病叶(50片)、煤烟病叶(103片)、缺素病叶(60片)、红蜘蛛叶(56片)和除草剂危害叶(85片),采集350～1 050 nm波段内的高光谱数据。分别利用一阶求导(1^stDer)、多元散射校正(MSC)和中值滤波(MF)方法对原始(Origin)高光谱数据进行预处理,对预处理后的高光谱数据采用主成分分析(PCA)和竞争性自适应重加权(CARS)算法提取特征波长,CARS降维得到的特征波长分别为10个、 5个、 12个和10个,4组PCA提取的特征波长均为7个,两种方法所得特征波长范围都集中在700～760 nm波段内。对全波段(FS)使用极限梯度提升树(XGBoost)算法,特征波长使用支持向量机(SVM)建立柑橘病叶多分类模型。采用XGBoost建立的检测识别模型有Origin-FS-XGBoost, 1^s...     

分散固相萃取结合超高效液相色谱-串联质谱法同时测定柑橘中春雷霉素与噻霉酮残留

建立了分散固相萃取结合超高效液相色谱-串联质谱(DSPE/UPLC-MS/MS)同时测定柑橘中春雷霉素和噻霉酮残留的分析方法。柑橘全果和果肉分别以含0.5%甲酸和含0.5%氨水的乙腈-水(7∶3,体积比)溶液提取,经十八烷基硅胶(C₁₈)净化上机,用Waters ACQUITY UPLC^? HSS T3色谱柱分离。以0.2%甲酸水-甲醇为流动相进行梯度洗脱,多反应离子监测模式(MRM)扫描,以基质匹配标准曲线外标法定量。结果显示:目标化合物在0.5～200μg/L质量浓度范围内线性关系良好(r²>0.999),检出限(LODs)为0.006～0.04μg/kg,定量下限(LOQs)为5～10μg/kg;加标回收率为73.4%～104%,相对标准偏差(RSD,n=6)为1.6%～9.6%。该方法易于操作,灵敏度高,适用于柑橘中春雷霉素和噻霉酮残留的同时检测。     

Properties of the Polycomplex of Apple Pectin with Benzimidazolyl-2-methylcarbamate Hydrochloride after Micronization

X-ray diffraction, microscopic, and sorption studies of benzimidazolyl-2-methylcarbamate hydrochloride (BMCHC) with various types of pectin showed that the structure of the mixtures depends on the composition, grinding conditions, and pectin type.     

Pectin recovery from model solutions using a laboratory-scale ceramic tubular UF membrane module

In this work the feasibility of the recovery of a commercial sample of citrus pectin from model solutions using a temperature- and pressure-controlled bench-top ultrafiltration (UF) plant equipped with a ceramic tubular, 20 kDa nominal molecular weight cut-off (NMWCO), UF membrane module, was assessed.     

Identification and determination of chemical constituents of Citrus reticulata semen through ultra high performance liquid chromatography combined with Q Exactive Orbitrap tandem mass spectrometry

Citrus reticulata semen, a traditional Chinese medicinal material, has desirable medicinal and dietary properties. In this study, a method combining ultra high performance liquid chromatography with Q Exactive Orbitrap tandem mass spectrometry was established and validated for the identification and analysis of the chemical components of C. reticulata semen for the first time. The evaluation of different retention times and fragmentation characteristics, as well as comparative analysis with the literature, resulted in the identification of 35 chemical constituents, including 21 flavonoids and 14 other compounds. The 21 flavonoids derived from C. reticulata semen were reported for the first time. Seven of the chemical components of C. reticulata semen were quantitatively analyzed using the developed method under the optimal conditions. The results showed that the content of limonin, hesperidin, nobiletin, synephrine, tangeretin, 3,5,6,7,8,3′,4′‐heptamethoxyflavone and 5‐hydroxide‐6,7,8,3′,4′‐pentamethoxyflavone in C. reticulata semen was 11.1666, 0.0404, 0.0092, 0.0255, 0.0087, 0.0010, and 0.0008 mg/g, respectively. This study demonstrated that the ultra high performance liquid chromatography Q Exactive Orbitrap mass spectrometry based method can be used to rapidly and reliably analyze the chemical constituents of C. reticulata semen. These results provide a scientific basis for further studies of C. reticulata semen.     

Stereoisomer separation of flavanones and flavanone‐7‐O‐glycosides by means of nanoliquid chromatography employing derivatized β‐cyclodextrins as mobile‐phase additive

A nanoliquid chromatographic method for the stereoisomer separation of some flavanone aglycones and 7‐O‐glycosides has been proposed employing a C18 capillary column and a chiral mobile‐phase additive such as cyclodextrin. The chiral separation of eriodictyol, naringenin, and hesperitin was obtained by addition of carboxymethyl‐β‐cyclodextrin to the mobile phase, whereas eriocitrin, naringin, narirutin, and hesperidin diastereoisomers were resolved by using sulfobutyl ether‐β‐cyclodextrin. The influence of the composition of the mobile phase, the length of the capillary column, and the flow rate on the chiral recognition were investigated. At optimum conditions, baseline separation for the selected aglycones and glycosylated forms were achieved with a mobile phase consisting of 50 mM sodium acetate buffer pH 3 and 30% methanol containing 20 mM of carboxymethyl‐β‐cyclodextrin and 10 mM of sulfobutyl ether‐β‐cyclodextrin, respectively. Precision, linearity, and sensitivity of the method were tested. Limits of detection and quantification for the studied flavanone glycosides were in the range 1.3‐2.5 and 7.5‐12.5 µg/mL, respectively. The method was used for the determination of the diastereomeric composition of the flavanone‐7‐O‐glycosides in Citrus juices after solid‐phase extraction procedure.     

Complexation in the Nitrolignin-Pectin-Copper Ion System

Potentiometric titration, spectrophotometry, and viscosimetry were used to study complexation of nitrolignin macromolecules, pectin, and their mixture with copper ions. The salt mechanism of formation of intramolecular polymer-metal complexes was established. Stability constants and extinction coefficients of the complexes were measured.     

超高效液相色谱-三重四极杆-离子阱质谱法检测柑橘中螺虫乙酯及其4种代谢产物

建立了超高效液相色谱-三重四极杆-离子阱质谱定量检测柑橘中螺虫乙酯及其4种代谢产物残留的分析方法。样品以QuEChERS技术为前处理方法进行净化、浓缩,在电喷雾电离（ESI）源、正离子模式下,采用MRM监测模式分析,以基质匹配外标法定量。螺虫乙酯及其4种代谢产物在2~1000 μg/L线性范围内具有良好的线性关系,相关系数（R²）>0.99;方法的检出限（LOD）为0.08~0.49 μg/kg,定量限（LOQ）为0.26~1.62 μg/kg;空白样品添加回收率为94.0%~98.7%,相对标准偏差为1.1%~5.3%。田间试验结果表明,在施药最高推荐量60 mg/kg （有效成分）下,柑橘果肉、果皮、全果样品中螺虫乙酯及其4种代谢产物残留总量分别为5.93~14.20、11.30~17.86和1.30~16.51 μg/kg,残留量均低于国家标准最大残留限量值1.00 mg/kg。该方法操作简便,快速准确,灵敏度高,分离效果好,能够有效降低基质干扰效应,准确度与精密度均能达到定量分析要求,适用于柑橘中螺虫乙酯及其代谢产物残留的定性定量检测。     

A covalently cross‐linked microporous polymer based micro‐solid phase extraction for online analysis of trace pesticide residues in citrus fruits

Covalently cross‐linked microporous polymers are a new class of highly cross‐linked porous network materials with large surface area and potential superiority in sample pretreatment. In this work, a covalently cross‐linked microporous polymer was well designed and synthesized by condensation of acylhydrazines in terephthalic dihydrazide with aldehyde groups in 1,3,5‐benzenetricarboxaldehyde. The adsorption mechanism was explored and discussed based on π‐π stacking interaction and steric effect. Then, a covalently cross‐linked microporous polymer was employed as the adsorbent of online micro‐solid‐phase extraction coupled with high‐performance liquid chromatography for the enrichment and analysis of trace pesticide residues in citrus fruits. The method was successfully applied to the online analysis of sugar orange and Huangdigan samples with the detection limits of 0.10–0.30 μg/kg. It was satisfactory that chlorpifos and triazophos in real sugar orange and Huangdigan samples could be actually found and quantified at concentrations of 0.20 and 0.51 mg/kg, respectively. The recoveries of sugar orange and Huangdigan samples were in the range of 70.0–103 and 74.0–119% with relative standard deviations of 0.4–9.7 and 0.5–9.2% (n = 3), respectively. The proposed method was accurate, reliable, and convenient for the online simultaneous analysis of trace pesticide residues in citrus fruits.