差示扫描量热法及其发展趋势

差示扫描量热仪可以测定多种热力学和动力学参数,如比热容、反应热、转变热、相图、反应速率、结晶速率、高聚物结晶度及样品纯度等。该仪器具有使用温度范围宽(-175~500℃)、分辨率高和试样用量少的优点。本文论述了差示扫描量热仪的特点、目前我国与差示扫描量热法相关的标准以及方法的未来发展趋势。未来在聚合物的结晶性研究和相变材料的热焓变化测量方面,差示扫描量热法(differential scanning calorimetry,DSC)会有更广泛的应用。在物质的鉴别方面,熔点的精确测量也会起到很重要的辅助作用。未来期待温度范围更宽的DSC仪器的出现,同时,红外-气相-差式扫描联用技术及热重-差式扫描量热联用仪器的更进一步发展会使得联用技术在未来得到更多的重视。     

差示扫描量热法测定谷氨酸纯度

目的:研究差示扫描量热法(DSC)测定谷氨酸纯度的可行性。方法:以铟和锌校正仪器,考察样品粒径、试验气氛、升温速率和样品质量等因素对DSC测定结果的影响,并在最佳条件下测定谷氨酸纯度;比较DSC法和中国药典2015版滴定法的测定结果。结果:当称样量为3 mg,升温速率为40℃/min时,DSC测得谷氨酸纯度为99.74%,精密度为0.07%。滴定法测得谷氨酸纯度为99.72%。结论:DSC法准确度高、操作简便,可用于谷氨酸的纯度测定。     

差示扫描量热法及其在猪肉凝胶机理探索中的应用

通过差示扫描量热法研究不同压力水平下凝胶的形成过程,初步探索凝胶形成机理。结果表明,凝胶的主要成分为肌球蛋白,200MPa蛋白质已经变性,400MPa蛋白质聚集,600MPa蛋白质凝胶形成。本研究结果能够为超高压诱导猪肉凝胶品质控制提供理论依据。     

差示扫描量热法测定番茄红素的纯度

差示扫描量热法（differential scanning calorimetry，简称DSC）是法定的药物纯度测试手段之一，可以快速、方便、准确地测定高纯度化工、医药产品。本文应用此项技术对纯化出的番茄红素晶体进行了纯度测定。并将测定结果与HPLC法和分光光度法做了比较，结果表明DSC法具有较高的准确度。     

应用差示扫描量热法测定胶原蛋白热滞活性

采用酶法从猪皮中制备胶原蛋白,并对其纯度进行了鉴定。在此基础上,利用差示扫描量热法对制备的胶原蛋白进行热滞活性的测定,考察了保留温度(-0.18、-0.088、0.013、0.13、0.23℃)、胶原蛋白浓度(0.1、0.5、1、2.5、5、10、15、20、50 mg/ml)及升降温速率(0.5、1、2.5、5、10℃/min)对热滞活性的影响。结果表明:所制备猪皮胶原蛋白为典型的Ⅰ型胶原蛋白,纯度较高,其分子量约为330 kD;当胶原蛋白浓度为20 mg/mL,保留温度为0.12℃,升降温速率为10℃/min时胶原蛋白热滞活性最高,为0.61℃。测定胶原蛋白热滞活性时保留温度的选取至关重要,而升降温速率对热滞活性无显著影响。     

差示扫描量热法对金枪鱼鱼油热氧化动力学研究

利用差示扫描量热法(DSC)研究了金枪鱼鱼油的热氧化动力学.通过对DSC曲线的分析表明,金枪鱼鱼油的酰基甘油组成复杂,脂肪酸种类比较多.用Flynn-Wall-Ozawa法和Kissinger法计算金枪鱼鱼油的热氧化反应动力学参数,两种计算方法得到的动力学参数具有一致性.     

差示扫描量热法测定奶粉的热稳定性

以差示扫描量热法对全脂奶粉、脱脂奶粉、全脂甜奶粉及中老年奶粉的热稳定性进行了研究,运用Ozawa和Kissinger方程求得各种奶粉的活化能,比较了这几种不同成分的奶粉的热稳定性,分析了奶粉成分对奶粉热稳定性的影响。结果表明,热稳定从高到低的顺序依次为脱脂奶粉、全脂奶粉、中老年奶粉、全脂甜奶粉,并且牛乳脂肪、植物油、蔗糖会降低奶粉的热稳定性。     

差示扫描量热法检测富锌涂料中的锌含量

介绍了富锌涂料的防腐原理及分类。富锌涂料中含锌量的多少直接影响涂料的质量。差示扫描量热法的分析原理．用该方法测定富锌涂料中锌粉含量的优点。     

差示扫描量热法和质量平衡法测定林丹的纯度

目的通过差示扫描量热法(differential scanning calorimetry,DSC)和质量平衡法(mass balance,MB)2种不同方法对林丹(γ-丙体六六六)纯度标准物质进行纯度分析的研究。方法基于Van’t Hoff原理,即物质的熔融曲线来算出杂质含量,利用DSC法对林丹进行纯度分析;采用气相色谱面积归一化法测量林丹的主成分纯度值,顶空-气相色谱法测量溶剂残留,卡尔费休测定水分和灼烧法测定灼烧残渣来最终确定林丹纯度。结果 DSC法测定林丹纯度为99.92%,不确定度为0.05%,质量平衡法测得林丹纯度为99.74%,不确定度为0.02%。结论 2种不同原理的方法对林丹纯度的测量有较好的一致性。DSC法方法简单,可操作性强,所需样品量较小,对仪器精度要求较高,相对不确定度较大。质量平衡法适用于所有有机纯物质的纯度分析,考察因素较多,分析较全面,且不确定度相对较小,方法准确度高。     

差示扫描量热法测定钛合金的相变温度

采用差示扫描量热法测定了四种不同钛合金TC27、TA15、TC4、TB6的β相变温度。四种不同钛合金的测试曲线体现出类似的规律,TG线一直保持不变说明升温过程中没有发生氧化反应,在500℃前由于释放残余应力呈现放热现象,而在后向吸热方向偏移,这个过程发生了相变。通过对DSC曲线求一阶导数,其峰值即为β相变温度。通过对比四种不同钛合金差示扫描量热法和金相法的测试结果,两者相当接近,因此差示扫描量热法也是一种有效的测试钛合金β相变温度的方法。     

Glass Transition Temperatures Determined using a Temperature-Cycling Differential Scanning Calorimeter

Glass transition temperatures, T_g, of polystyrene, polyvinylpyrrolidone, polydextrose, gelatin, corn flakes, pasta, and aqueous glucose/glycine solutions were determined using a differential scanning calorimeter which cycled the temperature while the net temperature increased at a constant rate. Operating conditions of the modulated differential scanning calorimeter^(tm) (MDSC^(tm)) for optimizing the endothermic baseline shift associated with the glass transition were a scan rate of 5°C/min with an amplitude of ± 1°C over a modulation period of 60 or 100 sec. The MDSC successfully separated the glass transition from other irreversible thermal changes in simple food ingredients. While the MDSC did not distinctly determine T_g of complex food systems at low moisture contents, glass transitions were observed for solutions and food systems at higher moisture contents. T_g values from MDSC were reproducible and similar to those from standard DSC.     

Subzero Glass Transition of Waxy Maize Starch Studied by Differential Scanning Calorimetry

A mixture of waxy maize starch and water (1:2, w/w) was heated in a differential scanning calorimeter (DSC) pan to different temperatures to obtain different degrees of gelatinization. Each pan was then quenched to ‐30°C and rescanned, and the subzero glass transition temperature (T_g′) of the content was determined. A three‐phase model of a starch granule—a mobile amorphous phase, a rigid amorphous phase, and a crystalline phase—was used to interpret results and explain the glass transitions in starch. Waxy maize starch had an onset gelatinization temperature (T_o) of 61.5°C, peak temperature (T_p) of 70.3°C, and completion temperature (T_c) of 81.7°C. The T_g′ was clearly noted after the starch and water mixture was heated to T_p and T_c, but was small and barely observable when the mixture was heated up to T_o and immediately cooled to ‐30°C. When the starch and water mixture was heated to 55°C, which was 6°C below the T_o, and held for 2 h, a T_g′ was observed. Moreover, T_g′ began to appear and was observable if the starch and water mixture was heated to 10°C below gelatinization onset temperature (51°C) and annealed for 2 h without any gelatinization. Further holding at ‐7°C showed a clear subzero glass transition of annealed native starch granules.     

南极磷虾抗冻蛋白热滞活性的差示扫描量热法评价

本研究采用差示扫描量热（differential scanning calorimetry,DSC）法评价了南极磷虾抗冻蛋白的热滞活性 （thermal hysteresis activity,THA）并进行了优化实验。以纯化的南极磷虾抗冻蛋白为研究对象,采用DSC法研究 了样品的升降温速率、样品质量浓度、冰晶含量、缓冲体系等对南极磷虾抗冻蛋白THA的影响。结果表明,南极磷 虾抗冻蛋白分子质量约为76 kDa,THA为1.76 ℃。通过优化实验确定以DSC法评价南极磷虾抗冻蛋白的THA升降温 速率为1.00 ℃/min,样品质量浓度为1.0 mg/mL,冰晶含量为10%～15%之间;不同的缓冲体系对THA也有较大的影 响。因此,DSC法可以用于南极磷虾抗冻蛋白的THA评价,重要参数经过优化后能够有效地评价抗冻蛋白的THA。     

用差示扫描量热法测定调温针织物的热性能

介绍了差示扫描量热法（DSC）的原理、用途及用法,测定了罗纹空气层织物的相变温度和相变焓,得到了其DSC曲线图。结果表明该织物具有良好的温度调节功能。     

Differential Scanning Calorimetry of Beef/Kappa-Carrageenan Mixtures

The thermal properties of kappa-carrageenan (KC) and/or beef under various ionic conditions were evaluated using Differential Scanning Calorimetry (DSC). The single endotherm observed for 2% aqueous KC (Tmax at 53°C) shifted to 54–59°C with addition of 1–3% NaCl and 0.35% sodium tripolyphosphate. Three endotherms were observed for post-rigor bovine semimembranosus meat (Tmax at 57, 66 and 80°C). Addition of salt/phosphate to beef had greater effects on Tmax than did 2% KC. On rescanning following 24 hr refrigerated storage, beef samples showed no thermal response, while KC treatments and beef/KC mixtures showed single endotherms at 53–63 and 69–76°C, respectively, indicating a wide shift in melting temperature of KC both in the presence of meat and at higher ionic strength.     

Measurement of Food Thermal Conductivity Using Differential Scanning Calorimetry

To measure thermal conductivity of foods, an attachment to a differential scanning calorimeter was constructed. A needle probe with a 40 gauge type-T thermocouple was used to measure the temperature of a cylindrical food sample. The DSC heating pan temperature was maintained at 40°C, and then raised to 50°C. The average thermal conductivities of rutabagas, radish, parsnip, turnip, potato, green apple, and carrot were 0.447, 0.499, 0.392, 0.480, 0.552, 0.405, and 0.564 W/m°C, respectively, for a temperature range between 40–50°C. The DSC method was reliable, precise, and a relatively rapid technique for determining thermal conductivity of foods.     

State Diagram of Freeze-dried Garlic Powder by Differential Scanning Calorimetry and Cooling Curve Methods

ABSTRACT: The state diagram of freeze-dried garlic powder was developed using freezing curve, glass transition line, and maximal-freeze-concentration condition. Freezing points of garlic powder were measured by differential scanning calorimetry (DSC) and the cooling curve method, whereas glass transitions were measured by DSC. The freezing curve and glass transition line were modeled using the Clausius-Clapeyron equation, adjusted with unfreezable water, and the Gordon-Taylor model, respectively. Maximal-freeze-concentrated condition was found as X '_s (characteristic water content) = 0.82 [ X '_g (characteristic solids content) = 0.18] with the characteristic temperature of glass formation being T '_m (characteristic glass transition) =−38.6°C and T '_m (characteristic end point of freezing) =−26.0°C. Other characteristic glass transitions T "_g and T ‴_g equal to −29.3°C and −48.6°C, respectively.     

差示扫描量热法对DHA、EPA甘油酯的热氧化动力学研究

利用差示扫描量热法(DSC)对DHA和EPA甘油酯的热氧化动力学进行了研究。通过对DSC曲线的分析表明:DHA和EPA甘油酯的酰基甘油组成较复杂,而脂肪酸种类较少。用Ozawa法和Kissinger法计算DHA和EPA甘油酯的热氧化反应动力学参数,两种计算方法得到的动力学参数具有一致性。     

Apparent Specific Heat of Chicken Breast Patties and their Constituent Proteins by Differential Scanning Calorimetry

Chicken breast meat yielded three endothermic transitions, with peak transition temperatures of 53,70, and 79°C. Comparison with the purified protein fractions indicated that these transitions corresponded to denaturation of myofibrillar (53°C) and sarcoplasmic (70 and 79°C) proteins. The apparent specific heat profile of chicken breast meat was successfully modeled as a weighted average of the apparent specific heat of the constituent proteins. The specific heats of sarcoplasmic protein, myofibrillar protein, and chicken breast meat were strongly influenced by temperature; however, the specific heat of stromal protein was nearly constant across the temperature range considered (i.e., 10 to 100°C).     

合浦珠母贝珍珠层的差示扫描量热分析

采用差示扫描量热仪对合浦珠母贝珍珠层进行了初步研究,发现珍珠层文石相变成方解石时表现为445℃左右的放热峰,与合成文石相变时呈现吸热峰明显不同.珍珠层文石这种异常的热相变特征可能是由纳米级文石储存的过剩焓引起的.