傅里叶变换红外光谱结合化学计量学方法对白酒基酒的快速定性和定量分析

白酒基酒等级的准确评判对白酒的质量控制至关重要,是白酒分级储存和勾兑的重要依据。目前白酒基酒分级是在生产车间班组工人初步分级基础上,通过专业评酒人员的人工感官审评结合气相色谱法测定主要酯类物质含量最终确定白酒基酒的等级。人工感官审评和气相色谱分析方法繁琐,耗时费力,很难实现实时快速检测。红外光谱技术具有快速分析、无损检测及灵敏度高和重现性好等优点,在食品品质检测领域得到广泛应用。运用傅里叶变换红外光谱(FTIR)和衰减全反射(ATR)技术结合化学计量学方法对不同等级白酒基酒及其主要酯类化合物进行快速定性和定量分析。采用线性判别(LDA)和误差反向传播人工神经网络(BPANN)分析模型对不同等级白酒基酒进行判别,线性判别分析训练集和测试集总体识别率均达到100%,BPANN分析训练集和测试集总体识别率均在95%以上。采用区间偏最小二乘法(siPLS)对四种主要酯类化合物进行定量分析,己酸乙酯、乳酸乙酯、乙酸乙酯和丁酸乙酯含量的训练集模型相关系数分别为0.986 4,0.991 5,0.970 2和0.951 4,测试集模型的相关系数分别为0.982 4,0.961 9,0.905 2和0.808 0。结果表明,傅里叶变换红外光谱技术结合化学计量学方法能有效实现不同等级白酒基酒的准确判别,同时基酒中主要酯类化合物的快速检测定量模型效果良好,能满足白酒生产中的分析检测要求,为白酒基酒等级的快速判别提供一种客观而准确的分析方法,有效提升白酒的智能化生产水平。     

基于移动窗口相关系数光谱法的白酒品牌快速判别技术研究

为满足白酒品牌判别领域快速检测的迫切需求,提出了一种以紫外光谱为输入,移动窗口相关系数法为手段的白酒品牌快速判别新方法。研究以海之蓝酒作为对象品牌,实验结果显示各批次海之蓝酒在实验波长区间存在较高的吻合一致性,基于紫外光谱原始谱图的相关系数值和基于移动窗口光谱计算所得的相关系数值均达到0.99以上。由于其他洋河系列白酒与海之蓝酒均属于洋河酒厂生产,原料来源、生产制备工艺等存在较高的相似性,此时若仅使用紫外光谱原始谱图数据结合相似度算法进行品牌判别,则定量化的判别区分存在一定困难。移动窗口法可有效提高谱图细节差异,突出光谱在特征谱段的形状、强度、变化趋势差异,提高实验谱图在细节结构差异辨认分析能力。经过研究筛选,发现以移动窗口相关系数结合紫外光谱特征谱段(270～295 nm)可提高洋河系列酒间的谱图差异,实现这种有较高相似性白酒品牌的判别区分。此外,市售六种其他品牌白酒及乙醇作为对照组,进一步论证了该方案的可行性。该研究的创新之处在于提出了一种移动窗口相关系数光谱法进行白酒品牌快速判别分析的新思路,该方法同时具备速度快,操作简便等优点,具有较高的实际应用潜在价值,并可为其他食品的质量安全判别分析研究提供借鉴。     

离子色谱-串联质谱法检测酒类产品中10种有机酸

建立了一种离子色谱-串联质谱(IC-MS/MS)测定白酒、黄酒、干红葡萄酒3种酒类样品中10种有机酸含量的方法。白酒样品氮吹后,经去离子水稀释,用IC-MS/MS分析检测;干红葡萄酒样品和黄酒样品,对比不同固相萃取小柱净化能力,最终选择石墨化炭黑固相萃取小柱进行净化,经去离子水稀释,用IC-MS/MS分析检测。选用高容量、强亲水性的Dionex IonPac^TM AS11-HC型阴离子分析柱进行分离,以淋洗液自动发生器在线产生的KOH水溶液为淋洗液,进行梯度淋洗。淋洗液经抑制器抑制后直接进入电喷雾电离串联质谱(ESI-MS/MS),采用负离子模式电离,多反应监测(MRM)模式检测,外标法定量。在该实验条件下:草酸、富马酸、马来酸、苹果酸、酒石酸、柠檬酸、奎尼酸和乌头酸在0.05~2 mg/L范围内线性关系良好;琥珀酸在0.05~5 mg/L范围内线性关系良好;乳酸在0.05~10 mg/L范围内线性关系良好(相关系数r²>0.99)。10种有机酸的检出限(S/N=3)在1.0~8.0 μg/L范围内,定量限(S/N=10)在3.5~26.5 μg/L范围内,在3个不同浓度的添加水平下,平均回收率在83.0%~112.1%之间,相对标准偏差≤9.1%,满足检测要求。该方法前处理简单,不使用有机溶剂,不需进行衍生化处理,测定快速、准确,灵敏度高,适用于3种酒类样品中10种有机酸的定量分析,为酒类食品的风味及品质测定提供方法支持。     

Investigating Lignin-Derived Monomers and Oligomers in Low-Molecular-Weight Fractions Separated from Depolymerized Black Liquor Retentate by Membrane Filtration

Base-catalyzed depolymerization of black liquor retentate (BLR) from the kraft pulping process, followed by ultrafiltration, has been suggested as a means of obtaining low-molecular-weight (LMW) compounds. The chemical complexity of BLR, which consists of a mixture of softwood and hardwood lignin that has undergone several kinds of treatment, leads to a complex mixture of LMW compounds, making the separation of components for the formation of value-added chemicals more difficult. Identifying the phenolic compounds in the LMW fractions obtained under different depolymerization conditions is essential for the upgrading process. In this study, a state-of-the-art nontargeted analysis method using ultra-high-performance supercritical fluid chromatography coupled to high-resolution multiple-stage tandem mass spectrometry (UHPSFC/HRMSⁿ) combined with a Kendrick mass defect-based classification model was applied to analyze the monomers and oligomers in the LMW fractions separated from BLR samples depolymerized at 170–210 °C. The most common phenolic compound types were dimers, followed by monomers. A second round of depolymerization yielded low amounts of monomers and dimers, while a high number of trimers were formed, thought to be the result of repolymerization.     

应用多级液液微萃取结合气质联用定量白酒中的角鲨烯

将多级液液微萃取与气相色谱-质谱联用技术相结合建立了白酒中微量角鲨烯的快速定量方法。将白酒稀释后,用戊烷-乙醚混合溶剂(1∶3,体积比)进行多级微萃取,有机相浓缩后气质联用分析。结果显示,角鲨烯在0.62~159.88μg/L范围内具有良好的线性关系,相关系数为0.995 5,角鲨烯的检出限为0.17μg/L,当加标浓度为2,20,40μg/L时回收率分别为78.1%,85.0%和103.5%,相对标准偏差(RSD)分别为12.1%,8.9%和7.0%。该方法具有简便快速、准确灵敏、萃取效率高、有机溶剂消耗少等优点,适合白酒中痕量角鲨烯的定量分析。     

衰减全反射-紫外/可见光谱技术应用

本文对衰减全反射法(ATR)的光学测定原理、衰减全反射-紫外/可见光谱方法(ATR-UV)的特点以及它们在一些典型的工业过程溶液,如高浓度和含有大量固体颗粒和微乳液聚合等体系检测的应用进行了综述。ATR-UV光谱技术适宜实时地反馈工业过程溶液的组分改变和浓度变化,从而帮助我们了解该过程的进展。这些优良的特性能帮助我们开发在线的传感器,因此可用于监测许多典型的工业过程溶液。其方法简单、迅速,一般无需对试样进行预处理或稀释。ATR-UV作为光谱学测定的重要波段,其技术开发将在化工过程检测方面具有重要的意义。     

猪毛水解母液中氨基酸的反相高效液相色谱分析

A new method for separation and quantification of amino acids by pre-column derivatization withphenylisothiocyanate(PITC ) and reversed-phase HPLC is described. Seventeen amino acids were separatedin 30 min at room temperature.The method has been successfully applied to the determination of amino acidcomposition in the solution which was prepared by hydrolyzing pig hair and extration of cystine.     

纸浆卡伯值的可见分光光度法在线测量

卡伯 (Kappa)值是纸浆质量的重要指标 ,而纸浆中的木素含量决定了纸浆的卡伯值。该文研究了用可见分光光度法在线测量酸法制浆过程蒸煮液中溶出的木素含量去预测纸浆中木素含量和纸浆卡伯值的方法 ;确定了合适的可见光光谱测量波段 (460～580nm) ;建立了纸浆卡伯值与蒸煮液吸光度 (A)的相关方程。结果显示卡伯值与A之间有良好的线性关系 ,为实现蒸煮过程纸浆卡伯值的在线测量提供了依据。     

Cure characteristics and properties of NBR composites filled with co‐precipitates of black liquor and montmorillonite

Acrylonitrile‐butadiene rubber (NBR) composites filled with co‐precipitates of black liquor and montmorillonite (CLM) were prepared by mechanical mixing on a two‐roll mill. The cure characteristics, mechanical properties, thermal properties, and thermo‐oxidative aging properties of NBR/CLM composites were evaluated. Scanning electron microscopy and transmission electron microscopy showed that the filler particles were well dispersed in the NBR/CLM composites. The scorch time and optimum cure time increase with increasing filler loading. A remarkable enhancement in tensile strength, elongation at break, 300% modulus, and shore “A” hardness was also observed. When the loading of CLM was 40 parts per hundred rubbers, it showed about seven times increase in tensile strength, about 1.8 times increase in elongation at break, about three times increase in 300% modulus, and about 1.3 times increase in shore A hardness, respectively, as compared with those of pure cured NBR. Thermal properties and thermal oxidative aging properties, in general, were also improved with loading of this novel filler. Copyright © 2011 John Wiley & Sons, Ltd.