Impact of reader antenna polarisation, distance, inlay design, conveyor speed, tag location and orientation on the coupling of UHF RFID as applied to modified atmosphere packaged meat

Undetected RFID tags make the potential benefits of RFID unattainable. This study aimed to determine the most significant factors that affect RFID and particularly its application to the traceability of meat. Experimental parameters included five RFID tag inlays, two levels of conveyor speeds, five variations of beef sample and an empty container, 12 tags per test sample, three distances and two types of reader antenna polarisations. Tag detection rates were determined in three replicates per combination of test parameters. A GLM ANOVA was carried out on tag detection rate. In decreasing order of significance in terms of the effect on mean tag detection rate were distance, sample, inlay design, conveyor speed and reader antenna polarisation. Interaction of these factors also proved significant, in decreasing order of importance were reader antenna * inlay, sample type * distance, inlay * distance, sample type * inlay, sample type * reader antenna, distance * speed, sample type * speed and finally sample type * distance * speed. Linearly polarised antenna preformed better overall at detecting tags, with 63% mean detection rate compared with circularly polarised antenna with 57% mean detection rate. Varying the tag inlay resulted in mean detection rates of between 62% and 88%. Ideal transponder location on package was reader antenna polarisation dependent, but generally tags facing reader antennas exhibited better detection rate. Results revealed that the under side of the package was the most un-detectable transponder location, considering the placement of reader antennas on top, left and right sides of the sample. Conveyor speed also proved significant with a variation from 0.5 to 1.0 m/s resulting in an average detection rate ranging from 62% to 57%, respectively. Circularly polarised antennas are believed to perform better in cases of random tag orientation on products. It can be concluded that RFID systems implementation in the meat supply chain requires a holistic approach where distances, polarisations, inlay type, meat composition and conveyor speed need to be considered.     

超高效液相色谱-串联质谱法同时测定海藻肥中的甘露醇和甜菜碱

建立了超高效液相色谱-串联质谱法同时检测海藻肥中甘露醇和甜菜碱的新方法。使用Waters BEH C18色谱柱,流动相为乙腈和5 mM乙酸铵溶液,流速为0.3 mL/min,柱温为35 ℃。采用正负离子同时扫描的方式测定,甘露醇和甜菜碱m/z为89和59.2;母离子的m/z分别为181和118,结果以外标法进行计算。结果表明,甘露醇和甜菜碱在本方法中的线性范围分别为5-50 和0.05-0.5 mg/L,当S/N为3时检出限分别为0.18和0.083 mg/L。两种物质分别在3个水平进行加标回收实验,甜菜碱的平均加标回收率在80.3-109.44%之间;甘露醇的平均加标回收率在85.52-106.55%之间,满足实际应用需求。     

凝胶渗透色谱净化—气相色谱法测定奶油中有机氯农药残留

作者采用凝胶渗透色谱（GPC）对奶油中8种有机氯农药进行样品前处理,气相色谱—电子捕获检测器进行测定,以保留时间定性,峰面积定量。在10~800 ng/mL浓度范围内,8种有机氯农药的线性良好,相关系数在0.9981~0.9996,回收率在92.4%～117.0%,RSD在1.83%～7.92%,方法检出限为0.65~2.33 μg/kg,满足奶油中有机氯农药残留检测要求。     

UPLC-MS/MS法检测稻米及土壤中扑草净除草剂的残留量

建立检测稻米及土壤中扑草净的UPLC-MS/MS方法。稻米和土壤样品经乙腈和混合液提取,甲醇/二氯甲烷溶解,PSA固相萃取柱净化,氮气吹干后经UPLC-MS/MS测定,外标法定量。建立了水稻及土壤中提取扑草净残留量的液相色谱-质谱/质谱测定方法。扑草净在稻米及土壤中的最低检测质量分数分别为0.01mg/kg;最小检出量5×10~11g;稻米添加回收率为82.7%~105.3%,土壤中添加回收率为79.6%~103.3%;稻米的RSD为2.6%~3.6%,土壤的RSD为3.2%~5.2%。建立方法准确、快速、灵敏度高,能够满足扑草净残留量分析的要求。     

超高压高效液相色谱法测定茶酒中茶氨酸含量

[目的]研究茶酒中茶氨酸含量的分析方法。[方法]以邻苯二甲醛(OPA)为衍生剂,采用超高压高效液相色谱测定茶酒中的茶氨酸。[结果]检测茶氨酸的线性范围为0.1~100.0μg/m L,线性方程可拟合为Y=53.57X-41.664,相关系数r为0.999 59,该方法的最低检出限达到0.05μg/g(以S/N=3计)。样品中茶氨酸的含量为0.25 mg/kg,加标试验的回收率在99.6%~100.1%。[结论]该方法快速、简单、定量准确,可在茶氨酸的测定分析中推广应用。     

超高压技术在天然产物萃取中的应用

论述了超高压技术在中药制剂萃取、果蔬饮料加工、微生物有效成分萃取、烟草香味成分萃取及在胸腺肽、乌头注射液等萃取中的应用,其萃取效果明显优于传统方法,可在常温下进行,避免了高温对有效成分的破坏,提高得率,减少能耗,降低成本,绿色环保,是一种具有广阔应用前景的新技术。     

超干种子老化方法比较研究

本试验种用谷子、绿豆，经４０℃及４５℃，湿度ＲＨ＝９５％－１００％老化６天及５天。然后测各含水量的５项活力指标。经生物统计表明：谷子４０℃，４５℃二处理间差异显著，且４０℃高温老化６天时间，在不同含水量的组合上，除含水量０．８５％外，其余二因子组合均优于４５℃老化６天的不同含水量处理，且有０．０１显著差异。绿豆老化温度亦以４０℃较好，种子含水量老化结合谷子和绿豆均以５．８％处理效果最好，二种作物经     

UPLC-MS/MS法同时测定牛奶中替米考星、地塞米松、氟苯尼考和氯霉素残留

试验旨在建立一种同时测定牛奶中替米考星（tilmicosin）、地塞米松（dexamethasone）、氟苯尼考（florfenicol）和氯霉素（chloramphenicol）的超高效液相色谱-串联质谱（ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS）法。牛奶样品经乙腈提取后,将提取液通过Oasis PRiME HLB固相萃取小柱净化,净化后的样液经氮吹浓缩后,用样品稀释液溶解并用正己烷进一步除去脂肪获得待分析样品,进行UPLC-MS/MS分析。采用CAPCELL PAK C18 MGⅢ-H色谱柱（2 mm×100 mm,3 μm）进行液相色谱分离,以甲醇（A）-含0.01%甲酸的0.1 mmol/L甲酸铵溶液（B）为流动相进行梯度洗脱：0~1.0 min,90%至60% B;1.0~3.0 min,60%至30% B;3.0~4.4 min,30%至20% B;4.4~4.5 min,20%~90% B;4.5~6.0 min,90% B。在多反应监测（multiple reaction monitoring,MRM）模式下进行质谱测定,以基质匹配标准溶液外标法定量。结果显示,替米考星、地塞米松、氟苯尼考和氯霉素在1.0~100.0 μg/L范围内均具有良好的线性关系（r>0.999）。方法的最低检测限（limits of detection,LODs）为0.1~0.2 μg/kg,定量限（limits of quantity,LOQs）为0.2~0.5 μg/kg,当4种化合物在牛奶中的添加水平为0.5、5.0和25.0 μg/kg时,回收率为78.6%~94.7%,相对标准偏差（relative standard deviations,RSDs）为2.4%~10.1%。本试验建立的UPLC-MS/MS方法简便、灵敏、准确,适用于牛奶中替米考星、地塞米松、氟苯尼考和氯霉素的同时测定。     

不同超干方法与几种蔬菜种子储藏效应的研究

 采用硅胶干燥、真空冷冻干燥、低温低湿干燥以及加温干燥4 种方法将6 种蔬菜种子的含水量降到5 %以下, 在常温储存条件下保存10 年后进行的发芽试验表明其发芽率与10 年前比较没有明显变化, , 唯加温干燥的种子降低了萌发时抵抗逆境的活力, 种子生活力均未降低。     

Light‐induced reduction of FE3+ as related to causes of chlorosis in cotton

In growth chambers, cotton (Gossypium hirsutum L. genetic selection ‘M8') was grown in a synthetic growth medium under four light regimes: low pressure sodium (LPS), LPS + Incandescent (Inc), cool white fluorescent (CWF) and CWF + Inc lamps at 22 C under LPS lamps. Less chlorosis developed at 26 C than at 22 C and less under LPS + Inc than under LPS lamps. All plants were green under CWF and CWF + Inc light. Green and chlorotic plant tissue contained about the same concentrations of Fe. The proposed hypothesis was that chlorotic tissue’ contained less Fe²⁺ than green tissue. Chlorotic leaves treated with FeSO₄ turned a green color. Enough CWF + Inc light passed through an intact leaf to reduce Fe³⁺ to Fe²⁺ in vitro. Also in vitro, Fe³⁺ was reduced by CWF, by Inc, but not by LPS light. The amount of Fe³⁺ reduced during an illumination period was directly proportional to the quantity of light used. In vitro, citrate and malate enhanced Fe³⁺ reduction, whereas phosphate, pyrophosphate, OH^‐, Cu²⁺, Ni²⁺, Mn²⁺, Zn²⁺, and F^‐ all inhibited Fe³⁺ reduction by light. Orthophosphate was about 8 times as effective as organic P in decreasing Fe³⁺ reduction. Citrate largely alleviated the inhibitory effects of Pi and pH (up to pH 6). The data also provide a possible explanation of a role for many of the elements known to induce or aggravate Fe chlorosis (inhibit Fe³⁺ reduction). Quantity and quality of light apparently play key roles in plant growth as related to reduction of Fe³⁺ to Fe²⁺ in plant tops.