果蔬农药残留快速检测技术的研究与前景分析

近些年来,由于农业生产片面追求产量,化肥和农药的施用量不断增加。由于我国的农业生产大都是小规模的农户分散生产,量小面大,不好监管,致使高毒农药的使用屡禁不止,农产品中的农药残留问题日益严重。为此,阐述了国内外水果蔬菜农药残留快速检测技术的研究和应用状况,并简要介绍了直接光谱分析法、免疫分析法、生物传感器法和酶抑制率法的检测原理。结合我国农业生产分散经营的现状,通过各种方法的对比分析得出结论:直接光谱分析和酶抑制率法比较适合在我国发展应用。     

氨基葡萄糖硫酸盐的制备及其性质

以甲壳素的浓盐酸水解产物氨基葡萄糖盐酸盐为原料 ,通过阴离子交换层析法制备氨基葡萄糖硫酸盐 ,并对其的部分性质进行研究。采用本方法制备的氨基葡萄糖硫酸盐产物的氨基葡萄糖含量为 71.6 0 % ,硫酸根含量为 18.2 5 % ,氯离子含量为 0 .0 38%。经纸层析鉴定 ,以吡啶、乙酸乙酯、水和冰醋酸按体积比 5∶5∶3∶1组成的溶剂系统进行展层 ,氨基葡萄糖硫酸盐的Rf 值为 0 .36。将氨基葡萄糖硫酸盐产物的晶体重新溶解于 2 0℃水中时 ,它的比旋光度随时间的延长而下降 ,1.5h后趋于稳定 ,从 92 .1°降低至 5 6 .7°。对它的红外光谱鉴定表明 ,在波数为 330 3.9、14 15 .6、12 15 .6、1181.2、1118.7、10 93.7和 10 34.4cm-1处有特征吸收峰。通过对氨基葡萄糖硫酸盐产物的元素分析 ,碳、氢、氮和硫的含量分别为 2 9.6 3%、6 .34%、5 .39%和 6 .5 6 %。     

光声光谱技术在植物叶子结构与功能分析中的应用

用光声光谱技术测试了黄杨叶片,分析了其层状结构与功能的关系,探索了这一原位测试技术在植物学研究中应用的前景。     

农药微乳剂热力学稳定性微观机制研究

 利用冷冻断裂电镜研究方法研究了表观稳定的农药微乳剂的微观结构 ,并通过光散射技术测定了O/W型微乳剂分散质点的流体力学半径 ,同时还测定了相关样品的主要表观指标。试验结果表明 ,随着微乳体系中表面活性剂 /水 (w/w)比值的减小 ,微乳剂分散质点流体力学半径变大 ,直至成为双连续结构 ,并依此提出了一种农药微乳剂热力学稳定的可能机制。这一发现使得从微观机制上解释农药微乳剂的热力学稳定性 ,指导热力学稳定的农药微乳剂的研究开发 ,并从根本上解决农药水基化制剂热贮稳定性这一关键技术问题成为可能。     

树形对适收期黄花梨糖度VIS/NIR光谱检测的影响研究

针对树体的光通透性影响果实糖分的积累,不同树形的果实品质存在差异的问题,研究了树形对适收期黄花梨糖度可见/近红外光谱检测模型的影响。采集了适收期前后6个批次、不同树形(开心形和棚架形)的黄花梨果实480个进行实验,两类树形果实糖度差异显著(p0.05),采用同一树形黄花梨建立的模型预测均方根误差(RMSEP)分别为0.69°Brix、0.64°Brix,相对分析误差RPD分别为2.08、1.97;单一树形全部样品建立的模型对不同树形样品的RMSEP分别为1.31°Brix、1.07°Brix,RPD分别为1.14、1.36;2类树形联合模型RMSEP为0.59°Brix,RPD为2.38。结果表明,树形对适收期黄花梨糖度预测模型的精度和稳健性均有较大影响,对进一步研究近红外光谱技术在田间水果采收期品质及最佳采收期检测的应用有一定的参考价值。     

大豆油脂肪酸近红外模型的建立和品质鉴定

本文介绍了一种利用BRUKER MATRIX-I仪器快速检测和监控大豆油新鲜度及脂肪酸组分的新的检测方法。选择310份大豆油样品,新鲜度指标酸价(AV)、过氧化值(POV)和脂肪酸组分分别采用国标的方法检测,并结合近红外光谱进行定量模型的建立和验证。结果表明:新鲜度指标酸价、过氧化值及5种特征脂肪酸模型决定系数R2均接近1,其中酸价、过氧化值及亚油酸的模型决定系数R2>0.9,校正均方差(RMSECV)与预测均方差(RMSECP)数值接近,且两者均较理想。同时能够根据脂肪酸组分含量,对大豆油进行掺假鉴别,表明利用近红外光谱模型能够较好地监控大豆油的质量,从而保证原料的稳定性和安全性。     

NIRS technology for fast authentication of green asparagus grown under organic and conventional production systems

This study sought to evaluate the ability of near-infrared reflectance spectroscopy (NIRS) to classify intact green asparagus as a function of growing method (organic vs. conventional) during postharvest refrigerated storage, and as a function of harvest month and postharvest cold storage duration. It also sought to identify the portion of the spear best suited for this purpose. A total of 300 green asparagus spears (Asparagus officinalis L., cv ‘Grande’), were sampled after 7, 14, 21 and 28 d of refrigerated storage (2 °C, 95% RH) and at commercial harvest time. Three commercially available spectrophotometers were evaluated for this purpose: a scanning monochromator (scanning range 400–2500 nm), a diode-array Vis/NIR spectrophotometer (range 400–1700 nm) and a handheld MEMS spectrophotometer (range 1600–2400 nm). Models constructed using partial least squares 2-discriminant analysis (PLS2-DA) correctly classified 91% of samples by growing method using the diode array instrument, between 86% and 91% using the scanning monochromator and between 82% and 84% using the handheld spectrometer. The tip and the middle portion of the spear proved to be the most suitable for this purpose employing the MEMS instrument. Using similar models, the diode array instrument correctly classified 100% of samples by harvest month, compared with between 97% and 98% using the scanning monochromator and between 87% and 96% using the handheld instrument. Models also correctly classified between 66% and 97% of samples by postharvest storage time, depending on the instrument used. The results indicate good performance of the prediction models, particularly for predicting harvest month and growing method, determination of the latter being of considerable importance for the authentication of organic asparagus at industrial level.     

木材电热远红外线干燥内部温度的实验研究

用电热远红外线干燥大量木材,发现木材内部温度高于外部温度的现象,并作了初步分析:(1)在特定条件下,木材干燥内温高于外温的快慢时间,取决于木材的含水率与厚度,厚度、含水率大者则慢,反之则快。(2)随树种材质而不同,材质致密者慢,疏松者快。(3)木材内外温差的大小,则与上述条件相反。远红外线干燥木材,主要是木材纤维素、木素和水分等强烈地吸收远红外线电磁波,其吸收率可达90％以上;辐射、吸收、再辐射、再吸收,如此循环,促进了木材含水率与干燥温度均内高外低,方向一致,达到了同步干燥目的。蒸发木材中水分1kg耗电1kwh。     

Studies on the Microscopic Mechanism of the Thermodynamic Stability of Pesticide Microemulsion

The cryo-fracture electron microscope was used to study the micro-structure of pesticide microemuisions. The hydromechanical radius (Rh) and the distribution (fRh) of pesticide microemulsions were determined by photo-correlation spectroscopy. This study showed that the Rh was significantly greater when the ratio of surfactants to water (w/w) decreased to 20/31 from 27/26, and a bicontinuous structure was formed when the ratio dropped to 15/36. These results explained the relationship between pesticide properties and the microscopic structure, and provided a good method for studying the microscopic structure of pesticide formulations.