聚苯胺修饰钨丝针型复合微PH传感器的研究及在水果测试中的应用

由电聚合法将聚苯胺修饰的钨丝电极作为ｐＨ敏感电极,把Ａｇ－ＡｇＣｌ体系填入针型塑料管内构成参比电极,把经聚苯胺修饰的钨丝电极安置入该针型参比电极内构成复合针型微ｐＨ传感器,在ｐＨ２￣１２范围内,该传感器呈现Ｎｅｒｎｓｔ响应,斜率为５５ｍＶ／ｐｈ,响应时间〈１ｍｉｎ,该传感器成功地应用于水果内微区ｐＨ的测定。     

聚苯胺修饰钨丝针型pH传感器的研究及在河鲫鱼测试中的应用

将聚苯胺修饰的钨丝电极为工作电极 ,Ag/ Ag-Cl电极为参比电极构成针型 p H传感器。该传感器在 p H2～1 2范围内呈现 Nernst响应 ,响应时间小于 1 min。该传感器成功地应用于河鲫鱼由活体到腐败过程中 p H值的变化测定。     

食用盐水溶液pH值的测定

为了消除碘缺乏病 ,使加入食用盐中的碘更加稳定 ,让全国人民吃到合格的碘盐 ,有些生产厂采取加入碱性物质使盐 ｐＨ值控制在一定范围。本方法探讨了食用盐水溶液ｐＨ值的测定 ,更好地指导生产。1　试验方法1 1　原理用电位法测定食用盐水溶液 ｐＨ值 ,是以玻璃电极作指示电剂 ,饱和甘汞电极作参比电报。1 2　仪器、设备1 2 1　ＰＨＳ - 3Ｃ型酸度计或其它型号的酸度计 ,测量范围 0～ 14ｐＨ ,分度值为 0 1ｐＨ单位。1 2 2　指示电极 :玻璃电极。1 2 3　参比电极 :饱和甘汞电极。1 2 4　实验用玻璃水银温度计。1 3　试剂和溶液本方法所…     

pH对油菜幼苗细胞膜及细胞保护系统的影响

皖油９号种子在ｐＨ３－１１的溶液中培养４ｄ的测定结果表明，ｐＨ５－８的缓冲液培养的油菜幼苗细胞膜透性低，ＭＤＡ含量较低，ＳＯＤ，ＰＯＤ，ＣＡＴ活性高，组织可溶性蛋白质含量高；ｐＨ大于５或大于８时，ＭＤＡ含量升高，细胞膜透性增大，ＳＯＤ，ＰＯＤ，ＣＡＴ活性及可溶性蛋白质含量下降。     

玉米原料细菌酒精发酵的研究

对运动发酵单胞菌ＺｙｍｏｍｏｎａｓｍｏｂｉｌｉｓＡＴＣＣ３１８２１的试验表明：该菌株最适发酵糖浓度为１５０～２００ｇ／Ｌ，ｐＨ为７左右。以玉米粉为原料，该菌株在发酵速率及淀粉出酒率等方面均比Ｋ字酵母优越。玉米粉在糖化３０ｍｉｎ，添加ＣＡＸ２０ｇ／Ｌ３５℃发酵４０ｈ后，酒精度达７２ｇ／Ｌ残糖（还原糖）４．２ｇ／Ｌ淀粉利用率９１．５％；淀粉出酒率４８．５％（按无水酒精计）。     

无花果曲霉（NRRL 3135）与黑曲霉（AsN 70）植酸酶产酶条件的研究

本文重点进行了无花果曲霉（Ａｓｐ．ｆｉｃｕｕｍＮＲＲＬ３１３５）和黑曲霉（Ａｓｐｎｉｇｅｒ７０）用固体培养法生产植酸酶的对比研究。结果表明：ＮＲＲＬ３１３５与ＡｓＮ７０均可以麸皮为主要原料，ＮＲＲＬ３１３５用缓冲液（ｐＨ４．８）控制ｐＨ，在３０℃±１℃培养８～９，产酶水平为５．２ｕ／ｇ干基；ＡｓＮ７０在不需要缓冲液控制ｐＨ的情况下，３０℃±１℃培养５～６天，其产酶水平可达４５．０ｕ／ｇ干基。     

钨丝聚苯胺修饰的pH传感器在河鲫鱼分析中的应用(英文)

钨丝聚苯胺修饰的为工作电极,Ag/AgCl为参比电极所构成的pH传感器,在pH2～12范围内呈现Nernst响应,时间小于1min。该传感器从河鲫鱼由活体到一步步腐败的过程中其pH值的变化得到了很好的分析。     

短小杆菌酶促合成二肽甜味剂Aspartame

研究多种因素对短小杆菌酶催化Ｌ－天冬氨酸（Ｌ－Ａｓｐ）和Ｌ－苯丙氨酸甲酯（Ｌ－ＰｈｅＯＭｅ）合成二肽甜味剂Ａｓｐａｒｔａｍｅ能力的影响。结果表明，反应最适ｐＨ为６．０，最适温度为４０℃，反应１０ｈ，催化能力为０．４７５ｇＡＰＭ／ｇ菌体，产率８０．５％，收率８１．０５％。     

酶处理纤维时需仔细选择溶液pH

通过分析ｐＨ对酶作用的影响,酶作用于纤维时的特殊性以及部分纤维的吸酸试验,认为纤维微环境ｐＨ与溶液ｐＨ有所不同,用酶处理纤维时,应使纤维微环境ｐＨ达到酶的最适ｐＨ才能最大限度发挥酶的效率,而纤维微环境ｐＨ不易测定,只能通过大量试验以确定溶液的最佳ｐＨ,使微环境中,ｐＨ达到酶的最达ｐＨ。     

里氏木霉利用麦糟生产纤维素酶

利用里氏木霉（Ｔｒｉｃｈｏｄｅｒｍａｒｅｓｅｉ）,以啤酒厂的废糟为原料,添加适量麸皮和稻草粉为培养基进行固态发酵,采用固体种曲混合接种,在４８ｈ翻曲,经１４４ｈ发酵后ＦＰＡ酶活达到３５７Ｕ／ｇ。以补加３％麸皮的酒糟水为培养基,调起始ｐＨ６．５培养９２ｈ的液体种子接种,ＦＰＡ酶活为１７８Ｕ／ｇ。     

L-半胱氨酸聚合膜亚硝酸盐安培传感器的制备及在食品检测中的应用

将L- 半胱氨酸通过循环伏安法电聚合到玻碳电极表面,制备了一种聚合物薄膜修饰电极,构建了一种新型NO2 安培传感器。实验结果表明,NO2 在该传感器上表现出良好的安培响应。其稳态电流与NO2 的浓度在1.0 × 10-6～4.4 × 10-5mol/L 范围内呈现良好的线性关系,检测限为1.0 × 10-7mol/L。此传感器具有灵敏度高、检测限低、抗干扰能力强等优点,应用于食品中NO2 含量的测量,结果满意。     

Rapid detection of pork meat freshness by using L-cysteine-modified gold electrode

In this research, a simple and rapid glucose sensor was developed and applied in the detection of meat glucose. The gold electrode was modified using L-cysteine and nanogold solution, and a polyglutamate–glucose oxidase (GOx) complex was prepared and dropped on the modified electrode; the electrostatic binding between the L-cysteine on the electrode surface and the polyglutamate moiety of the complex resulted in the formation of a GOx-attached electrode. Glucose in meat was detected, and the enzyme electrode showed a quick response. The optimum operating conditions for this sensor were determined as follows: 0.1 M citrate buffer pH 5.0 was found to be suitable for this experiment, and the temperature was kept between 25 and 30 °C which is the suitable range for the GOx activity. A linear relationship was found between 0.1 and 0.9 mM/mL. High pressure liquid chromatography (HPLC) was also used to detect pork meat glucose, and total volatile basic nitrogen (TVBN) production was as well detected as a quality index of pork meat freshness. The results showed that the developed sensor was fast and reliable method for the detection of glucose in meat.     

Biosensors fob food industry

Novel biosensor systems were constructed for food industry. In order to determine fish freshness, a multifunctional enzyme sensor system was developed by combining a double membrane consisting of a 5'‐nucleotidase membrane and a nucleoside phosphorylase‐xanthine oxidase membrane with an oxygen electrode. Each nucleotide concentration was determined as the current decreased. One assay was completed within 20 min. Good comparative results were observed between the KI values determined by the sensor proposed and by the conventional method. An enzyme sensor for meat freshness consisted of a monoamine oxidase‐collagen membrane and an oxygen electrode. The response time of the electrode was 4 min. A linear relationship was observed between the amine (tyramine) concentration in the range 50–200 μM and the difference in current. Monoamine in meat extract was determined by the enzyme sensor. Micro‐glutamate sensor was constructed using silicon fabrication technology. Calibration curve for glutamate sensor was obtained in a glutamate concentration range between 5–50 mM. Moreover, an immuno sensor based on piezoelectric crystal was applied to the determination of toxic bacterium C. albicans. The frequency shift is correlated with C. albicans concentration in the range 10⁶ 5×10⁸ cell/ml.     

联苯三唑醇分子印迹电化学传感器的制备及识别性能研究

以联苯三唑醇为模板分子,通过电聚合邻苯二胺,在玻碳电极表面制备了对模板分子具有特异识别的分子印迹电化学传感器。实验选用铁氰化钾(K3[Fe(CN)6])作为电活性探针,采用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了该传感器的电化学特性,并且优化了制备条件,研究了印迹传感器对模板分子及其结构类似物的选择性响应。结果表明:在最佳聚合条件下,p H=7.2,模板分子:功能单体=1:4(c/c),聚合圈数15圈,洗脱时间为13 min,洗脱剂:0.5 mol/L硫酸:乙腈=1:9(V/V),连续洗脱10次之后,相对标准偏差为5.2%,且传感器性能无衰减现象。该分子印迹电化学传感器灵敏度高,抗干扰能力强,对联苯三唑醇及其结构类似物具有良好的选择性响应,可以对结构类似物分别进行测定,为快速检测食品中联苯三唑醇奠定了基础。     

磁性印迹固相萃取-印迹电化学传感器联用技术快速检测肉制品中的红霉素

本文旨在构建一种简便、快捷的肉制品中痕量红霉素磁性分子印迹固相萃取-印迹电化学传感器联用的分析方法。采用新型表面印迹技术,制备出对ERY具有高选择性与灵敏性的红霉素磁性分子印迹聚合物（MMIP）,再分别以MMIP作为固相萃取剂及电化学传感元构建印迹固相萃取-印迹电化学传感器（MMISPE-MMIP-sensor）联用技术快速检测系统。采用循环伏安（CV）及差分脉冲伏安（DPV）等方法对其电学性能进行探讨,通过红外光谱、扫描电镜（SEM）和透射电镜（TEM）对其结构和形态进行表征。实验考察了缓冲溶液pH和孵化时间对印迹电极的影响。结果表明,最佳缓冲溶液pH为7.5,富集时间为10 min。在最优实验条件下,该印迹电极的响应电流△I_R与ERY浓度的负对数（-logC_[ERY]）在1.0×10?10~1.0×10?5 mol/L范围内呈良好的线性关系,相关系数为0.991,最低检出限为1.0×10?10 mol/L。以AZI、STM、ROX三种结构类似物为干扰物,研究该印迹电极对ERY的吸附选择性。结果显示,该印迹电极只对红霉素分子具有特异识别作用而呈现最大响应值（0.72 mA）。重现性和稳定性实验结果显示该电极具有良好的重现性和稳定性。联用检测结果显示通过磁固相萃取和印迹电化学双预浓缩过程将样品中ERY富集浓度提高了9~12倍。     

Potentiometric Determination of Aluminum in Foods, Pharmaceuticals, and Alloys by AlMCM-41-Modified Carbon Paste Electrode

A new chemically modified electrode is constructed by incorporating AlMCM-41 into carbon paste matrix (AlMCM-41-MCPE) and used as a sensitive sensor for detection of aluminum in aqueous and nonaqueous solutions. The rapid exchange kinetics in the membrane results in a near-Nernstian behavior of the modified electrode and makes it a suitable potentiometric sensor for detection of aluminum. A linear response in concentration range from 1.0?×?10^?6 to 1.0?×?10^?1 mol/L (0.027 μg/mL–2.7 mg/mL) was obtained with a detection limit of 4.6?×?10^?7 mol/L for the potentiometric detection of aluminum. Selectivity coefficients of a number of interfering cations have been estimated. The interference from many of the investigated ions is negligible. The AlMCM-41-MCPE is suitable for use in aqueous solution of pH 2–6 and in partially nonaqueous medium. The modified electrode exhibited a fast response time (~8 s), good stability, and an extended lifetime. The developed sensor was used successfully for the determination of Al³⁺ in some alloys, drugs, and food products.     

Microbial Sensors for the Detection of Fish Freshness

A microbial sensor system consisting of immobilized living spoilage-causing bacterium, Alteromonas putrefaciens, and an oxygen electrode was prepared and applied to the continuous determination of fish freshness. Fish freshness was expressed as a ratio of A/B, where A is the current decrease of the microbial sensor obtained by the application of l0–50 μL fish extract and B is the current decrease by the equivalent volume of culture medium. Freshness of bluefin tuna and yellowtail meats stored in ice for up to 2 weeks was determined by both the proposed and the conventional K value enzyme sensor method. Good comparative results were obtained. One assay could be completed within 13 min.     

A biosensing method for detection of caffeine in coffee

A specific inhibition of 3′,5′‐cyclic phosphodiesterase (CPDE) from bovine heart by methylxanthines was used in combination with a pH electrode to develop a new biosensing method for the detection of caffeine in coffee. The potential response changes of the sensor were proportional to the concentration of caffeine in the range 0–4 mg ml⁻¹. The response time was about 2–4 min. The standard deviation of five measurements of a 0.2 mg ml⁻¹ caffeine solution was ±7.1 µg ml⁻¹. The electrode gave a detection limit of 0.6 mg l⁻¹ caffeine. The concentration of caffeine in espresso coffee was analysed. This model gave excellent correlation between observed and predicted caffeine values. This electrode exhibits advantages such as fast response, short conditioning time and low cost of the instrumentation used. We also expected to be able to perform the detection of caffeine in food and clinical analysis. © 1999 Society of Chemical Industry