超高效液相色谱-串联质谱法测定食用油中的叔丁基对苯二酚

目的：建立一套稳定可靠的使用超高效液相色谱- 串联质谱(UPLC-MS/MS)测定食用油中的抗氧化剂叔丁基对苯二酚(TBHQ)的方法。方法：用乙腈振荡萃取样品中的TBHQ,以乙腈- 水为流动相洗脱,以反相C18 柱作为分离柱,以电喷雾离子源为接口,负离子模式扫描,选择监测(SRM)模式检测,外标法定量。结果：本方法的检出限为0.10mg/kg,在0.05～2.5μg/ml 浓度范围内呈良好线性,相关系数大于0.999,回收率83%～115%。结论：实验结果表明该方法灵敏度高,检出限低,确证能力强,分析时间短,能够准确的测定食用油中的抗氧化剂TBHQ 的含量。     

高效液相色谱指纹图谱法测定广西不同产地粉葛和葛根中9种特征成分

目的建立高效液相色谱指纹图谱法测定分析广西不同产地粉葛和葛根中9种特征成分的方法。方法利用高效液相色谱法(high performance liquid chromatography, HPLC)同时测定粉葛和葛根中葛根素、3’-羟基葛根素、大豆苷、黄豆黄苷、染料木苷、大豆苷元、染料木素、刺芒柄花素、鹰嘴豆芽素A等9种特征成分的含量,建立广西不同产地粉葛和葛根的指纹图谱,并利用相似度分析从整体上对广西粉葛和葛根药材的质量进行评价。结果测定了8批次样品中的9种特征成分的含量。粉葛样品共标定15个共有峰,指认其中7个峰,与共有模式之间的相似度均大于0.97;葛根样品共标定34个共有峰,指认其中7个峰,与共有模式之间的相似度均大于0.99。结论广西不同产地的粉葛和葛根之间所含的化学成分具有一定的共性和差异性,该方法适合用于葛根和粉葛的质量控制。     

适于检测谷氨酸含量的Warburg仪器标定新方法

针对味精生产厂家使用Warburg仪器检测发酵液谷氨酸含量的特点,对笔者已经发表的、便于众多反应瓶与众多检压计作任意搭配使用的快速标定这种仪器的方法进行简化。根据实测数据与简单运算结果,由计算机输出的最终标定结果是,检压计与反应瓶作任意搭配使用时的瓶、计总容积和三个常数,它们是检压计读数增加1mm表明受检液体放出CO_2的μl数,含有谷氨酸的mg数、受检每升发酵液含谷氨酸的克数。 用这种方法对带有N支检压计的仪器作标定,在确保准确度情况下,工作最小于用常规方法取得同样结果所用工作量的1/N,N可以是任何数。     

液相色谱双柱法和高效离子交换色谱法测定低聚半乳糖含量比较

目的:优化对比液相色谱双柱法和高效离子交换色谱法两种测定低聚半乳糖含量的方法,同时建立一种新的低聚半乳糖换算系数(K值)计算方法;方法:对现有上述两种测定低聚半乳糖含量的检测方法进行对比分析,筛选出分离效果更好的糖柱,并进一步优化色谱条件。结果:优化后的液相色谱双柱法对低聚半乳五糖到低聚半乳八糖的分离效果明显提升,提高了测定准确度,而高效离子交换色谱法操作更加简便;根据不同样品选用不同K值来计算低聚半乳糖含量的方式可进一步提升结果的精确性。结论:两种方法均可有效对低聚半乳糖含量进行检验分析,高效离子交换色谱法检测灵敏度较高,且已被AOAC等国际权威机构纳入标准检测方法,可作为低聚半乳糖含量测定的标准仲裁法;液相色谱双柱法测定低聚半乳糖更为简便快捷,经济适用,可用于生产企业日常产品检测。     

液相色谱双柱法和高效离子交换色谱法测定低聚半乳糖含量比较

目的:优化对比液相色谱双柱法和高效离子交换色谱法两种测定低聚半乳糖含量的方法,同时建立一种新的低聚半乳糖换算系数(K值)计算方法;方法:对现有上述两种测定低聚半乳糖含量的检测方法进行对比分析,筛选出分离效果更好的糖柱,并进一步优化色谱条件。结果:优化后的液相色谱双柱法对低聚半乳五糖到低聚半乳八糖的分离效果明显提升,提高了测定准确度,而高效离子交换色谱法操作更加简便;根据不同样品选用不同K值来计算低聚半乳糖含量的方式可进一步提升结果的精确性。结论:两种方法均可有效对低聚半乳糖含量进行检验分析,高效离子交换色谱法检测灵敏度较高,且已被AOAC等国际权威机构纳入标准检测方法,可作为低聚半乳糖含量测定的标准仲裁法;液相色谱双柱法测定低聚半乳糖更为简便快捷,经济适用,可用于生产企业日常产品检测。     

一种用于过滤布等效孔径测量的方法

利用液体压强随深度增加和冒泡试验法原理,设计出一种通过稳定冒泡现象测量过滤布等效孔径的方法.此法首次将样品垂直放置,气体和液体被分置于样品两侧,使样品上液体压强分布不同,而气体压强分布相同.气体压强将气泡顶出液体侧,气泡冒出的数量随液体深度的增加而减少直至消失.在样品上测得任意6点的孔径值,取平均值作为等效孔径,用不确...     

Photo-scanning colorimetry of wood and transparent wood coatings

Although conventional spectrophotometers are well-known to give very accurate and reproducible measuring results of the wood surface colour, the areal resolution of this method is limited due to the fixed aperture size. In this study, the applicability of a colour calibrated flatbed scanner for areal-resolved colorimetry was investigated. For this purpose, the colorimetric values of several wood species calculated from images of a colour calibrated photo-scanner were correlated with those obtained by a conventional spectrophotometer. Further, this method was used to evaluate the discoloration of earlywood and latewood of Siberian larch (Larix sibirica) during Xenon arc exposure as a demonstration of the potential application of this method. In addition, an investigation concerning the possibility of image analysis for the evaluation of the colour change as a consequence of the application of transparent coatings was done. Good correlation among the measured methods could be found by applying relative colour values ΔL* Δa*, Δb* and ΔE*, whereas absolute colour values L*, a* and b* obtained rather weak correlations. The investigation of the relative discoloration of earlywood and latewood of Siberian larch showed a higher amount of discoloration in the earlywood. The investigation concerning the colour change induced by the application of transparent coatings showed that it is possible to evaluate the discoloration by the coating for earlywood and latewood separately. This could be the basis for a more quantitative comparison of quality parameters of coatings like the visual contrast enhancement effect, known as wet-look or “Anfeuerung” of transparent coatings. It was concluded that when evaluating colour changes on wood the use of a calibrated photo-scanner is a valuable addition to conventional spectrophotometry.     

分光光度法快速测定发酵液中杆菌肽效价

建立使用分光光度法测定发酵液中杆菌肽的方法,发酵液经预处理后使用杆菌肽敏感菌(藤黄微球菌)浊度测定杆菌肽效价.藤黄微球菌液体培养3h后,加入待测样品,再培养3h后600nm下测定吸光度,通过杆菌肽浓度与液体培养基浊度之间的线性关系测定杆菌肽效价.此方法检测准确、操作简单,可快速测定发酵液中杆菌肽效价.     

高效液相色谱法测定红景天提取物中红景天苷的不确定度评定

目的 对红景天提取物中红景天苷含量进行不确定度评定,通过查找不确定度的来源和影响因素,为优化评定方法和提高检测准确性提供依据。方法 样品中的红景天苷用甲醇进行提取,在波长275nm下,用紫外检测器进行测定。通过分析影响不确定度因素的来源, 对不确定度进行量化分析, 从而得出扩展不确定度。结果 由各不确定度分量评定结果可以看出, 当置信水平为95%,包含因子k=2时,红景天提取物中红景天苷含量的扩展不确定度为± 0.40 g/100g。不确定度主要来源于标准曲线拟合、测量重复性和标准溶液配制。结论 高效液相色谱仪应定期进行校准与维护保养,定期检查紫外灯能量和自动进样器的定量准确性,选用高校准级别的容量瓶,高纯度的标准品。而且检测人员应熟练掌握样品的各项处理步骤, 以提高检测准确性。     

Development of a Hyperspectral Computer Vision System Based on Two Liquid Crystal Tuneable Filters for Fruit Inspection. Application to Detect Citrus Fruits Decay

Hyperspectral systems are characterised by offering the possibility of acquiring a large number of images at different consecutive wavebands. To ensure reliable and repeatable results using this kind of optical sensors, the intensity shown by the objects in the different spectral images must be independent from the differences in sensitivity of the system for the different wavelengths. The spectral efficiency of the acquisition devices and the spectral emission of the lighting system vary across the spectrum and the images, and therefore the results can reproduce these variations if the system is not properly calibrated and corrected. This is particularly complex, when several LCTF devices are used to obtain large spectral ranges. This work presents the development of a hyperspectral system based on two liquid crystal tuneable filters for the acquisition of images of spherical fruits. It also proposes a methodology for acquiring and segmenting images of citrus fruits aimed at detecting decay in citrus fruits that has been capable of correctly classifying 98 % of pixels as rotten or non-rotten and 95 % of fruit.     

ESTIMATION OF AMINO NITROGEN IN WORTS AND BEERS USING EITHER NINHYDRIN OR 2,4,6-TRINITROBENZENE-1-SULPHONIC ACID

Colorimetric methods of estimating amino nitrogen have been calibrated, taking either glycine or leucine as the standard, and used to measure the amino nitrogen contents of worts and beers. Comparison of the 2,4,6-trinitrobenzene-1-sulphonic acid method with the ninhydrin procedure shows that amino nitrogen values differing by up to 15–20% can be obtained for the same sample and moreover that worts behave differently from beers.     

Modelling of coupled heat and mass transfer during a contact baking process

A mathematical model of coupled heat and mass transfer of a contact baking process is developed. In the current model formulation, a local evaporation of water is described with a reaction-diffusion approach, where a simultaneous diffusion and evaporation of water takes place. The resulting coupled model equations (unsteady state heat transfer, liquid water and water vapour) were solved using the Finite Element Method (COMSOL Multi-physics® version 3.5). During the baking process, local temperatures and overall moisture loss were measured continuously. The model - predicting temperature, liquid water content in the product and water in the vapour phase - was calibrated and partially validated using data obtained during baking of a representative food model (a pancake batter) under controlled conditions on a specially designed experimental rig. The unknown parameters in the model equations were estimated using the standard least squares method by comparing the measured with the predicted temperature profile. Good agreement was achieved between model predictions and the experimental values.     

固相微萃取-气相色谱-质谱联用法检测物流过程中液态乳质量

目的建立固相微萃取-气相色谱-质谱联用法检测物流运输前后液态乳质量。方法利用顶空固相微萃取,结合气质联用技术和吹扫捕集法分析液态乳制品中挥发性成分,检测牛奶中的氯仿和脂质降解程度。结果液态乳制品样品中有7种挥发性成分具有指示作用,主要是醛和酮;使用顶空分析能够量化氯仿污染物,脂肪分解的程度可以通过测量游离脂肪酸来量化。结论脂肪酸酶解产物可作为液态乳制品物流过程质量控制的生物标志物,固相微萃取的灵敏度和重现性满足液态乳制品物流过程的质量控制的要求。     

Precipitation behaviour of caseinomacropeptides and their simultaneous determination with whey proteins by RP-HPLC

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method on polyvinylbenzene/divinylbenzene copolymer resin was applied for the quantitative determination of glycosylated and non-glycosylated caseinomacropeptides (CMP), in presence of the major whey proteins (α-lactalbumin and β-lactoglobulin). The peak profile of the CMP-fractions was calibrated using the response factor determined by amino acid analysis. By omitting any critical precipitation step (e.g. trichloroacetic acid, TCA) usually applied to remove whey proteins, the method allows the simultaneous determination of the major whey proteins and CMP—the complete native spectrum—in a single run. As a prerequisite for forthcoming kinetic studies of CMP release, the precipitation sensitivity of individual whey proteins or CMP fractions against TCA or perchloric acid (PCA) was studied systematically. All CMP fractions were partially precipitated even at low TCA concentrations, whereas PCA treatment resulted in negligible decrease of CMP solubility.     

固液混装罐头食品固体中心冷点温度预测

本文探索了固液混装罐头食品的传热特性。应用CS—2型温度信息处理机测定了固液混装罐头食品的固体和汤汁中心冷点温度值。编了计算机程序,计算传热过程的参数j,f值。建立一系列的固体和汤汁冷点处的传热方程和确立罐头食品的固液传热比方程,可预测固体中心温度值,百分误差在允许范围内。本文提出的方法是一种较理想的预测固体中心温度方法,可供制订合理杀菌工艺条件之用。     

高压液相色谱法测定可乐饮料中咖啡因的探讨

<正> 饮料中咖啡因的高压液相色谱法测定,国内目前尚未见报道。本人参考国外有关文献,利用国产仪器和填料,研究了样品不经化学处理,直接进样测定咖啡因的色谱条件和可行性,结果较为满意,平均回收率为100.05％,该法简单快速,灵敏度高,测定一个样品仅需     

ESTIMATION OF α-, β- AND ISO-α-ACIDS IN HOPS,HOP PRODUCTS AND BEER USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Methods are described in which high performance liquid chromatography (HPLC) is used to estimate α-, β- and iso-α-acids in hops, hop products and beer. The chromatography relies on an isocratic elution of components from a polythene ‘cartridge’ column, and the method is calibrated with the pure substances as primary standards. Using such a column over 1000 analyses have been carried out without any significant loss in resolution or precision. The procedures are sufficiently rapid for use in commercial transactions and for quality control purposes. For hops and hop extracts coefficients of variation (%) of 2·5 and 0·8 were obtained respectively for α-acids. Values of 0·9 and 0·3 were obtained for iso-α-acids in isomerised extracts and beers respectively. For some isomerised extracts it has been observed that peaks in addition to those given by the iso-α-acids are present on the chromatogram. The current method recommended by the EBC over estimates the iso-α-acid content since these other constituents are included in the analysis.     

钒钼黄分光光度法检测液态特殊食品中磷含量的优化

目的建立钒钼黄分光光度法检测低磷含量液态婴幼儿配方食品、液态特殊医学用途配方食品等特殊食品中磷含量的分析方法。方法试样经消解,磷在酸性条件下与钒钼酸铵生成黄色络合物钒钼黄,于440 nm测定试样溶液中钒钼黄的吸光度值,幵与标准系列比较定量。对3种基质液态特殊食品的磷含量进行测定。结果增大称样量能满足方法准确度和精密度要求;称样量为4 g时,回收率范围为92.4%～107.0%,相对标准偏差为0.8%～3.7%;方法定量限为30 mg/100 g。结论该方法能够准确测定液态配方食品中较低含量的磷,适合液态婴幼儿配方食品、液态特殊医学用途配方食品等特殊食品中磷含量的测定。     

甘蔗亚硫酸法糖厂产糖率的灰色关联度分析及预测

运用灰色系统理论,对甘蔗亚硫酸法糖厂产糖率的影响因素进行灰色关联度分析,得到了诸因素对产糖率的关联序,在此基础上,建立了产糖率预测的ＧＭ（１,Ｎ）模型,实验结果表明,模型有较高的精度。     

固相萃取富集-高效液相色谱法测定大花红景天中微量元素硒

研究了用固相萃取富集,二极管矩阵检测器检测,反相液相色谱法测定大花红景天中微量元素硒的方法。样品中硒用邻苯二胺显色剂作柱前衍生,WatersSep-park-C18固相萃取微柱富集硒的邻苯二胺络合物,然后用乙腈和甲醇为流动相,WatersμBondapakC18色谱柱为固定相分离,用二极管矩阵检测器检测。方法相对标准偏差为2·40%,标准回收率为98·67%。该方法用于大花红景天样品的分析,结果令人满意。