傅里叶变换红外光谱法识别分析四种天然皮革材质

以国家部分标准皮革样品及市售皮革样品等天然皮革为样品,采用傅里叶变换红外光谱仪的衰减全反射附件--OMNI采样器,收集傅里叶变换红外吸收光谱,对光谱预处理后,提取红外光谱的特征信息,以2 925 cm-1和2 854 cm-1处的吸收峰面积比值为横坐标,1652 cm-1与1 552 cm-1处的吸收峰面积比为纵坐标,用Origin 7.0化学化工制图软件绘制二维分布图,对各种皮革样品进行识别分析.结果显示:猪皮革、牛皮革、马皮革的样品点分布效果好,而羊皮革的各样品点之间比较分散;猪皮革样品点明显区别于牛皮革、羊皮革和马皮革,马皮革样品点明显区别于牛皮革、羊皮革和猪皮革,而牛皮革和羊皮革的样品点分布有交叉.     

基于曲线拟合的形态相似鹅膏菌的傅里叶变换红外光谱研究

利用傅里叶变换红外光谱仪测试了形态相似的灰疣鹅膏菌、灰绒鹅膏菌和灰褶鹅膏菌的光谱,结果显示,它们的傅里叶变换红外光谱主要由蛋白质和多糖的振动吸收带组成,其蛋白质的吸收频率略有差。选择酰胺I带(中心频率1647cm-1)进行傅里叶自去卷积和曲线拟合处理后3种鹅膏菌中蛋白质在酰胺I带的吸收峰都由12个子峰叠加而成,其中在无序(1650cm-1)、α螺旋(1658cm-1)和β转角结构(1666cm-1)的振动吸收峰上,灰褶鹅膏菌吸收峰的面积百分比分别是20.98%、4.47%和17.14%,明显地区别于其它两种鹅膏菌(灰疣鹅膏菌:10.26%、12.58%和7.71%;灰绒鹅膏菌:14.33%、9.76%和8.83%)。在1683cm-1处的β转角吸收峰上,灰绒鹅膏菌吸收峰的面积百分比是1.92%,明显小于其它两种鹅膏菌(灰疣鹅膏菌:8.03%;灰褶鹅膏菌:6.65%)。研究表明:傅里叶变换红外光谱技术能提供大型真菌所含蛋白质二级结构信息。     

傅里叶变换红外光谱法对掺假橄榄油的快速鉴别

利用衰减全反射傅里叶红外光谱法对掺假橄榄油进行了快速鉴别研究。对掺入转基因大豆油、非转基因大豆油、花生油、玉米油、葵花籽油、调和油等的橄榄油采用160℃高温加热8h处理,通过观察样品加热前、后二阶导数光谱在988cm-1处特征吸收峰的吸光度变化,准确鉴别橄榄油是否掺假。该方法操作简便、前处理无需有机试剂,可作为市场筛查掺假橄榄油的快速鉴别方法。     

衰减全反射傅里叶变换红外光谱法同时测定叔丁醇和二叔丁基过氧化物

分别应用914 cm-1和875 cm-1处的甲基特征峰作为叔丁醇和二叔丁基过氧化物的定量分析峰,使用峰面积作为吸光度的评估方法,得到的标准曲线的相关系数(R2)分别是0.9987和0.9952,叔丁醇的加标回收率在95％～110％之间,应用衰减全反射傅里叶变换红外光谱法测定3个样品,计算结果的F值、t值和p值,数据表明衰减全反射傅里叶变换红外光谱法与气相色谱法的测定结果一致.     

涂石蜡大米傅立叶变换红外吸收光谱识别分析

针对11种未涂石蜡大米和18个涂不同量石蜡的大米样品,以石油醚提取的油脂为试样,采用傅立叶变换红外光谱仪,扫描样品的傅立叶变换红外吸收光谱,并对光谱进行预处理,提取红外特征信息,将2855与1746、1462与1163 cm-1处特征峰的面积比值为坐标,采用Origín 6.0软件作识别分类图.结果表明:特征峰的面积比值与所涂石蜡量成线性变化,大米油脂的特征峰面积比值在一定的区域分布,涂以0.05%以上石蜡的大米,其油脂特征峰面积比值与未涂石蜡米油脂的值有一定区别.     

模式识别法分析5种植物油脂

通过模式识别方法区分花生油、大豆油、米糠油、棕榈油和菜籽油。采用气相色谱法分析5种植物油脂的脂肪酸,用面积归一化法计算每个植物油脂样品的各脂肪酸相对含量。以每个植物油脂中9个脂肪酸的相对含量为变量,采用SPSS13.0软件的模式识别技术对119个植物油脂样品进行区分。由主成分分析图可知,花生油、大豆油、米糠油、棕榈油和菜籽油被清晰地分为5组。判别分析建立的判别方程能较好地实现样品的判别,自身验证和交互验证的准确率均为100%。另取每种植物油脂各5个样品(共25个)进行验证,识别准确率为100%。对调和有棕榈油的花生油进行主成分分析,在主成分分析图上,调和油的分布点在花生油分布区域与棕榈油分布区域之间。     

傅里叶变换红外光谱法检测火锅用牛油中固体石蜡

研究了傅里叶变换红外光谱法测定火锅用牛油中非法加入的固体石蜡,取市场贩卖的炼制凝固牛油1 g左右,用2 mol·L-1氢氧化钾乙醇溶液30 mL皂化,皂化完成后速冻皂化液,用自制小竹签挑取液面漂浮物于傅里叶变换红外光谱仪的固相样品测试台上,于450～3 500 cm-1波数范围内进行测定,在721cm-1波数处作定性检测.于空白的牛油样品中加入低至0.05%的固体石蜡即能检出明显的红外吸收谱图.     

傅里叶变换红外光谱法检测脑肿瘤

应用傅里叶变换红外光谱法检测了28例液氮冻存的离体脑肿瘤样本及其残留物(将脑肿瘤样本从ATR的ZnSe晶片上取下,样本在ZnSe晶片上沾染后留下的物质).结果发现,神经鞘瘤和神经上皮组织肿瘤(如星形细胞瘤等)的主要特征吸收峰存在明显差异,因此可从各个特征吸收峰的峰位、峰形及不同谱峰强度比的变化来初步鉴别脑肿瘤的性质,脑肿瘤组织样品残留物的红外光谱也可反映不同性质脑肿瘤的差异.与脂类糖蛋白以及核酸相关的谱带变化分析表明,通过特征峰强比(I1460cm-1/I1400cm-1,I1160cm-1/I1120cm-1和I1160cm-1/I1080cm-1)来鉴别肿瘤的性质与病理诊断结果的符合率超过85%.     

丁基黄药在CuO表面吸附的二维连续在线原位ATR-FTIR光谱研究

运用连续在线原位衰减全反射傅里叶变换红外光谱(ATR-FTIR)技术测定了纳米CuO表面对丁基黄药的吸附行为.在FTIR谱图中发现有峰的红移现象,吸收峰由1200 cm-1偏移到1193 cm-1,用超纯去离子水脱附,峰强度只有微小的变化,可判断丁基黄药在CuO表面发生了很强的化学吸附.通过对吸附行为进行二维(2D)红外光谱分析,分辨出吸附过程中光谱强度的变化顺序.二维异步相关光谱测定结果表明,1265 cm-1处振动吸收峰最先引起光谱强度的变化,1265 cm-1处吸收峰可归因为表面反应生成的双黄药和黄药分子聚集体的复合峰.根据1200 cm-1处黄药特征吸收峰强度的变化,进行吸附动力学模拟,得出CuO对丁基黄药的最大吸附量为529 mg·g-1,且吸附符合拟二级吸附动力学过程.     

红外光谱法对六氟磷酸锂的快速定量分析

本文建立了一种用傅里叶红外光谱(FT-IR)法快速定量分析LiPF6的方法。采用红外光谱(IR)法和X射线衍射(XRD)法对LiPF6样品进行了定性分析。选取LiPF6红外光谱847cm-1处的特征吸收峰为分析对象,利用吸光度峰面积积分法进行定量分析,由标准曲线可知,LiPF6的含量与其红外光谱特征峰的吸收强度有很好的线性关系,相关系数达0.9998,线性范围在0.04～25mg.mL-1,检出限可达0.02mg.mL-1。LiPF6样品定量测定的相对标准偏差(RSD)约为0.18%,回收率为96%～98%。     

Analysis of Peanut Oil Adulterated with Other Edible Oils by Spectrophotometry

Since peanut oil(PO) is more expensive than other seed oils, some PO is adulterated with other cheap seed oils, such as soybean oil, palm olein, cottonseed oil, corn oil and rapeseed oil. The conventional method for determining whether PO was adulterated is to detect the freezing point of oils. The proposed method for the determination of adulterants in PO was based on monitoring the change of absorbance when the sample was refrigerated. A special spectrophotometer was developed. A total of 10 kinds of POs from different suppliers were chosen and adulterated with other seed oils at the volume fraction levels ranging from 5% to 30%. A total of 150 samples were analyzed by the proposed method and the results were satisfactory.     

气相色谱-质谱法测定植物油中8种维生素E及其在芝麻油真伪鉴别方面的应用

建立了气相色谱-质谱（GC-MS）同时测定植物油中α-、β-、γ-、δ-生育酚和α-、β-、γ-、δ-生育三烯酚等8种维生素E的分析方法。植物油样品经甲醇超声提取、浓缩、定容,在分时段选择离子监测（SIM）模式下分离分析,采用外标法进行定量。结果表明,8种维生素E可实现基线分离;在0.01~1 mg/L范围内,所有目标物均呈良好线性关系,相关系数均大于0.99;检出限和定量限分别为0.03~0.25 mg/kg和0.10~0.83 mg/kg;在芝麻油中分别添加10、50和250 mg/kg 3个水平的8种维生素E进行加标试验,平均回收率为87.5%~107.4%,相对标准偏差（RSD）≤ 7.5%。所建立的方法简单、准确、可靠,且灵敏度高,可用于测定植物油中8种维生素E的含量。采用上述方法对芝麻油、大豆油、菜籽油、葵花籽油、花生油、玉米油和棕榈油等7种共75个植物油样品中维生素E的含量进行测定。结果显示,芝麻油与其他6种植物油中的8种维生素E的组成和含量均有显著差异性,因此该方法可作为芝麻油掺入其他植物油的特征鉴定指标。     

常压火焰离子化质谱技术对食用植物油快速分析的初探

建立了常压火焰离子化质谱(Ambient flame ionization mass spectrometry,AFI-MS)快速分析食用植物油(橄榄油、芝麻油、花生油和葵花籽油)的方法。AFI-MS检出食用植物油(橄榄油、芝麻油、花生油和葵花籽油)中的26种甘油三酯和11种甘油二脂。AFI-MS分析显示,不同的食用植物油(橄榄油、芝麻油、花生油和葵花籽油)得到的质谱图轮廓信息不同。通过对不同食用植物油的甘油三酯相对峰强度进行分析,可初步归纳出食用植物油的类型。AFI-MS分析食用植物油的操作简单,普通的打火机就可以作为离子源用于食用植物油的分析。这种便捷的离子化技术可以用于食用植物油的快速分析。     

Analysis of olive oil and seed oil triglycerides by capillary gas chromatography as a tool for the detection of the adulteration of olive oil

Individual triglyceride (TG) species of olive oil and several seed oils (corn, cottonseed, palm, peanut, soybean, and sunflower) are baseline separated on a WCOT TAP CB fused-silica capillary column by capillary gas chromatography (CGC) with a flame-ionization detector (FID) and either cold on-column or split injection. An adulteration of olive oil with a low content (< 5%) of these seed oils (except peanut oil) can be verified by the detection of the increasing levels of trilinolein or tripalmitin in olive oil in which these TG species are normally absent or present at very low levels (< 0.5%). An adulteration with over 20% peanut oil can be detected by the increasing levels of palmitodilinolein. TG species that can be coeluted with trilinolein in the reversed-phase high-performance liquid chromatographic (RP-HPLC) mode are baseline separated by the CGC technique, and their structures are identified by selective ion monitoring mass spectrometry. The following comparisons--the CGC-FID and RP-HPLC methods for detection of adulteration, cold on-column and split-injection modes for CGC-FID, and silylation or thin-layer chromatography pretreatment and simple dilution of one or more of the oil samples--are also presented. The normalized percentage area of the TG species is sufficient for the method limits used in this study. Mixtures of virgin olive oil with refined or residue olive oil could not be distinguished from the virgin type by the method used in this study.     

复热食用植物油结构变化的红外吸收光谱分析

利用衰减全反射(ATR)傅立叶红外光谱(FTIRS)法对市售优质品牌的8种植物油(转基因豆油、非转基因豆油、葵花籽油、花生油、玉米油、红花籽油、调和油、橄榄油)未加热及反复高温加热后的红外二阶导数光谱进行比较,发现复热食用油在反复高温加热下会使不饱和脂肪酸亚油酸、亚麻酸的含量降低,饱和脂肪酸棕榈酸和硬脂酸的含量增加;顺式脂肪酸的含量下降,反式脂肪酸的含量明显增加。确定以二阶导数光谱中3 009、988、966 cm-13处特征吸收峰的峰高判定是否为反复加热用油。此方法样品用量少、分析速度快,可从整体上了解油品的质量及成分,并可作为市场复热食用油的快速筛查方法,也可为地沟油检测方法的建立提供理论依据。     

Differentiation of vegetable oils by mass spectrometry combined with statistical analysis

The main triacylglycerol (TAG) composition of different plant oils (almond, avocado, corn germ, grape seed, linseed, mustard seed, olive, peanut, pumpkin seed, sesame seed, soybean, sunflower, walnut and wheat germ) were analyzed using two different mass spectrometric techniques: HPLC/APCI-MS (high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry) and MALDI-TOFMS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry).Linear discriminant analysis (LDA) as a multivariate mathematical statistical method was successfully used to distinguish different plant oils based on their relative TAG composition. With LDA analysis of either APCI-MS or MALDI-MS data, the classification among the almond, avocado, grape seed, linseed, mustard seed, olive, sesame seed and soybean oil samples was 100% correct. In both cases only 6 different oil samples from a total of 73 were not classified correctly.     

Reactive Extraction of Citric Acid Using Tri-n-octylamine in Nontoxic Natural Diluents: Part 1—Equilibrium Studies from Aqueous Solutions

Use of cheap, nontoxic, and selective solvents could economically provide a solution to the recovery of carboxylic acids produced by the bioroute. In this regard in the present paper, reactive extraction of citric acid was studied. Problems encompassing the recovery of the acid ([H₃A] _aq ^o ?=?0.1?C0.8) was solved by using tertiary amine (tri-n-octylamine, TOA) in natural diluents (rice bran oil, sunflower oil, soybean oil, and sesame oil). TOA was very effective in removal of acid providing distribution coefficient (D) as high as 18.51 (E%?=?95?%), 12.82 (E%?=?93?%), 15.09 (E%?=?94?%), and 16.28 (E%?=?94?%) when used with rice bran oil, sunflower oil, soybean oil, and sesame oil, respectively. Overall extraction constants and association numbers for TOA + rice bran oil, TOA + sunflower oil, TOA + soybean oil, and TOA + sesame oil were evaluated to be 35.48 (mol/l)^?1.46, 29.79 (mol/l)^?1.30, 33.79 (mol/l)^?1.51, and 37.64 (mol/l)^?1.65 and 1.46, 1.30, 1.51, and 1.65, respectively. Specific equilibrium complexation constants (K _E(n/m)) were also predicted using mathematical modeling.     

Analyses of Vegetable Oil Triglyceride Molecular Species by Reversed Phase High Performance Liquid Chromatography

Abstract

Triglyceride molecular species (TGMS) of 10 vegetable oils (olive, soybean, sunflower, corn, cottonseed, pumpkin seed, peanut, safflower, canola and palm oil) were separated and analyzed quantitatively by gradient, reversed phase high performance liquid chromatography with a flame ionization detector (FID). Identification of TGMS was made by comparison of experimental and calculated theoretical carbon numbers (TCN). The relationship between elution time and calculated TCN of each TGMS was linear. The FID response (area percent) was determined to be linear or proportional to weight percent. Nine of the oils showed significant differences between observed TGMS composition and     

Discriminating olive and non-olive oils using HPLC-CAD and chemometrics

This work presents a method for an efficient differentiation of olive oil and several types of vegetable oils using chemometric tools. Triacylglycerides (TAGs) profiles of 126 samples of different categories and varieties of olive oils, and types of edible oils, including corn, sunflower, peanut, soybean, rapeseed, canola, seed, sesame, grape seed, and some mixed oils, have been analyzed. High-performance liquid chromatography coupled to a charged aerosol detector was used to characterize TAGs. The complete chromatograms were evaluated by PCA, PLS-DA, and MCR in combination with suitable preprocessing. The chromatographic data show two clusters; one for olive oil samples and another for the non-olive oils. Commercial oil blends are located between the groups, depending on the concentration of olive oil in the sample. As a result, a good classification among olive oils and non-olive oils and a chemical justification of such classification was achieved.     

Determination of Organophosphorus Pesticides in Soybean Oil, Peanut Oil and Sesame Oil by Low-Temperature Extraction and GC-FPD

A low-temperature clean-up method for residue determination was developed and validated for 14 organophosphorus pesticides in soybean oil, peanut oil and sesame oil by gas chromatography with flame photometric detector (GC-FPD). A different matrix influenced the response and retention time of pesticides. Hence matrix-matched calibration standards were used to counteract the matrix effect. The pesticide responses in blank samples of soybean oil, peanut oil and sesame oil were within the linear range of 0.02–1 mg kg⁻¹ and the correlation coefficients were higher than 0.9989. Average recoveries obtained from different oil samples at three fortified levels were higher than 50% with relative standard deviations (RSDs) of less than 15%. The limit of detections (LODs) of studied pesticides ranged from 2 to 5 μg kg⁻¹. Thirty-nine commercial samples were analyzed, and the results were confirmed by gas chromatography–mass spectrometry (GC–MS) in selective ion monitoring (SIM) mode.