Chemical and Physical Characterization of Donkey Abdominal Fat in Comparison with Cow, Pig and Sheep Fats

The objective of this research was to investigate the physicochemical properties of donkey fat. Results show that donkey fat contains 59.38 % unsaturated fatty acids, 38.37 % saturated fatty acids, and 0.21 % trans fatty acids. The sn-2 monoglyceride present in donkey fat contain 67.91 % unsaturated fatty acids and 30.97 % saturated fatty acids. Donkey fat is also characterized by a total tocopherol content of 8.59 mg/100 g fat (7.90 mg/100 g fat α-tocopherol, 0.51 mg/100 g fat β + γ-tocopherol, and 0.18 mg/100 g fat δ-tocopherol), 0.0032 mg/100 g fat cholesterol, an acid value of 0.091 KOH (mg/g), an iodine value of 76.47 g/100 g, a peroxide value of 0.68 mmol/kg, a saponification value of 193 mg/g, a refractive index of 1.4666, and a specific gravity of 0.9144. The complete melting temperature was 40 °C. The content of unsaturated fatty acids (total and sn-2) in donkey fat is higher than cow, pig and sheep, while the content of trans fatty acids is lower. The tocopherol content is also higher in donkey fat compared to cow, pig and sheep fat. Interestingly, the fat with such processing has nearly no cholesterol. Generally speaking, donkey fat could be a good animal fat for human consumption.     

Measurements of Diacylglycerols in Skeletal Muscle by Atmospheric Pressure Chemical Ionization Mass Spectrometry

Diacylglycerol (DAG) is an intermediate lipid involved in the synthesis of phospholipids and triglycerides. As signaling regulators, DAG activate novel protein kinase C leading to decreased response to insulin in skeletal muscle. Alteration of DAG contents correlates with development of metabolic dysregulation in obese and diabetic conditions. Recent advances in lipidomics using mass spectrometry allow expanded measurements of various lipid species. This study describes a rapid measurement of DAG species using the triple quadrupole mass spectrometry using atmospheric pressure chemical ionization in a positive ion mode. DAG in the cells and muscle tissues were separated depending on differences in chain lengths and degree of unsaturation. The limit of detection and quantification for DAG was 0.2 to 17 pmol for this method. When C2C12 cells were treated with palmitate or oleate, we found a 12-fold and 2-fold DAG increase respectively compared to the no-treatment control. In the muscles of obese db/db mice, DAG levels were elevated by 6-fold compared to those of wild-type skeletal muscles. The present analytical method provides a rapid and sensitive quantification of DAG molecular species from various biological samples and can be used to correlate the degree of metabolic dysregulation with lipotoxic metabolites.     

Determination of milk fat in chocolates by gas-liquid chromatography of triglycerides and fatty acids

The combination of two routine methods is proposed to determine the content of milk fat (MF) in chocolates, which is applicable even in the presence of lauric fats or others. The content of MF is obtained from the sum of C₄₀, C₄₂, and C₄₄ medium-chain triglycerides, determined by capillary gas-liquid chromatography (GLC). A new method, based on methyl esters of lauric acid and on minor acids situated between myristic and palmitic, is proposed. It enables detection and estimation of potential lauric fats, as well as the determination of the actual content of MF. The influence of other vegetable and animal fats is discussed. We analyzed 45 MF samples extracted from industrial milk powders and from pure or fractionated MF for chocolate manufacturing or pastry by GLC of triglycerides. We also analyzed by capillary GLC the methyl esters from 22 of those fats. Mixtures of these 22 MF samples with a cocoa butter also were used for chromatographic analyses of methyl esters and triglyceride. Results from the various analytical methods have been presented.     

高效液相色谱-串联质谱法同时检测蔬菜、水果中21种农药多残留

建立了以固相萃取/高效液相色谱-串联质谱(LC/MS/MS)同时测定蔬菜、水果中痕量21种农药残留量的方法.蔬菜、水果样品提取液经固相萃取后采用C18柱分离,以0.1%甲酸乙腈-0.1%甲酸水溶液为流动相,梯度洗脱,以保留时间和质荷比对分离出的组分予以定性确证,用峰面积进行定量.结果表明,21种农药的质量浓度与其峰面积在一定的范围内呈良好的线性关系,样品中最低检出质量分数为0.0005～0.003 mg/kg,样品的平均加标回收率为76.34%～119.33%.方法简便、快速、灵敏,适用于蔬菜、水果中这些农药的同时分析.     

Determination of Bile Acids in Piglet Bile by Solid Phase Extraction and Liquid Chromatography-Electrospray Tandem Mass Spectrometry

An LC/MS/MS‐based method was developed for the determination of individual bile acids (BA) and their conjugates in porcine bile samples. The C18‐based solid‐phase extraction (SPE) procedure was optimized so that all 19 target BA and their glycine and taurine conjugates were collected with high recoveries for standards (89.1–100.2 %). Following this, all 19 compounds were separated and quantified in a single 12 min chromatographic run. The method was validated in terms of linearity, sensitivity, accuracy, precision, and recovery. An LOD in the low ppb range with measured precisions in the range of 0.5–9.3 % was achieved. The recoveries for all of the 19 analytes in bile samples were all >80 %. The validated method was successfully applied to the profiling of BA and their conjugates in the bile from piglets treated with exogenous glucagon‐like peptide‐2 (GLP‐2) in a preclinical model of neonatal parenteral nutrition‐associated liver disease (PNALD). The method developed is rapid and could be easily implemented for routine analysis of BA and their conjugates in other biofluids or tissues.     

HPLC-DAD法同时测定抗风湿类中成药及保健品中非法添加的化学药物

建立了同时测定抗风湿类中成药及保健品中非法添加的对乙酰氨基酚、马来酸氯苯那敏、吡罗昔康、萘普生、双氯芬酸钠、布洛芬的含量测定方法。采用高效液相色谱法,二极管阵列检测器,色谱柱为Diamonsil C18(4.6 mm×250 mm,5μm),以乙睛为流动相A,0.02 mol·L-1NH4Ac-0.05%HAc为流动相B,梯度洗脱,流速为1.0 mL·min-1,柱温40℃,检测波长为260 nm,在21~23 min内波长变为225 nm。各化学成分在相应的浓度范围内与其对应峰面积呈良好的线性关系,相关系数大于0.999。方法平均回收率分别为93.7%~98.3%,RSD为1.43%~2.81%。方法简便,准确,重现性好,可作为抗风湿类中成药及保健品中非法添加的化学药物检测方法之一。     

气相色谱-负化学电离源-飞行时间质谱筛查和定量测定天然香精中3种农药残留

为了快速筛查和定量检测天然香精中的农药残留,建立了香精中3种农药的气相色谱-负化学电离源-飞行时间质谱(GC-NCI-TOFMS)分析方法。优化了样品萃取、净化条件以及气相色谱和飞行时间质谱分析条件。样品以V(正己烷)∶V(乙酸乙酯)=1∶1为溶液,超声萃取30 min,萃取液经弗罗里硅土固相萃取柱净化后,进行检测分析。根据特征离子的精确质量数、氯同位素离子峰簇、碎片离子丰度比、保留时间对目标物进行定性鉴定,内标法进行定量测定。3种农药的线性相关系数均大于0.998 6,相对标准偏差4.5%,检出限为0.14~0.21μg/kg,3种农药的加标回收率为87%~107%。该方法简单快速、准确性高、灵敏度好,适用于香精中农药残留的快速筛查和定量检测。     

20%氟·唑磷乳油复配制剂分析方法的研究

介绍了杀虫剂三唑磷和氟虫腈复配乳油制剂的液相色谱分析方法。选用Hypersil ODS250mm×4.0mm5 μm 不锈钢色谱柱、配置紫外检测器(VWD) 及自动进样器的HP 1100高效液相色谱仪,进行液相色谱分离和测定。该方法操作简便、快速、准确。结果表明三唑磷和锐劲特的标准偏差分别为0.106 6 和0.012 6,变异系数分别为0.565 8%和1 .228%,平均回收率分别为99.00%和99.80%,线性相关系数分别为0.999 9 和0.999 7。     

高效液相色谱法测定白蚁防治药土屏障中的吡虫啉和伊维菌素

建立了测定白蚁防治药土屏障中的吡虫啉和伊维菌素的高效液相色谱法。目标物通过甲醇提取后,经SPE小柱净化,超高效液相色谱分离测定,分别进行了两个添加水平的加标回收实验。吡虫啉平均回收率:粘土96.05%~99.28%,RSD为2.60%~3.26%;砂土82.16%~83.55%,RSD为2.00%~2.28%。伊维菌素平均回收率:粘土92.99%~110.56%,RSD为2.31%~4.69%;砂土101.63%~101.70%,RSD为2.59%~5.12%。该方法具有简单、灵敏度高、重现性好等优点。     

分散固相萃取-UHPLC-MS/MS法测定水中5种苯脲类除草剂

建立分散固相萃取-超高液相色谱串联质谱(UHPLC-MS/MS)同时测定环境水样中5种苯脲类除草剂(敌草隆、利谷隆、灭草隆、异丙隆、绿麦隆)残留的分析方法。考察了吸附剂的种类与数量、水样pH、吸附剂的种类和体积等条件对除草剂回收率的影响。在最佳实验条件下,5种苯脲类除草剂在0.01~5.0μg/L范围内呈良好的线性关系(0.999 3~0.9999),方法检出限为2.04~3.12 ng/L。对环境水样的加标回收率分别为78.2%~108.3%,相对标准偏差RSD分别为6.8%~11.2%。本方法操作简便快速、稳定性好、灵敏度高,能够满足环境水体中苯脲类除草剂残留的分析要求。     

原子荧光法测定地质调查样品中的砷、锑、铋、汞

确定了各元素的最佳分析条件,在王水介质中连续测定地质调查样品中的砷、锑、铋、汞。该方法快速简便,分析结果与国家一级标样标准值相符。     

Determination of Alcohol Ethoxylates derivatized with Naphthoyl Chloride,in Waste Water Treatment Plant Influent,Effluent and Sludge Samples by Liquid Chromatography Mass Spectrometry

A new analytical procedure for the determination of alcohol ethoxylates (AE) in environmental samples such as influents, effluents and sludge from waste water treatment plants (WWTPs) was developed. Although some work had been previously published on the detection of AE in water samples, this is the first paper that deals with AE in sludge. Alcohol ethoxylates were removed from water samples by sorption on polymeric discs followed by extraction with methanol. The methanol extracts were cleaned up with two alumina solid-phase extractions (SPE) at different conditions of solvent polarity, one before and the other after derivatization with naphthoyl chloride. A final polishing step was carried out on a Florisil SPE column. Liquid chromatography/mass spectrometry with electrospray ionization was used to quantify AE as naphthoyl derivatives. The detection limits for AE ethoxymers range from 0.07 to 0.005 μg/L in water samples. The method was applied to an Italian WWTP in order to follow the fate of AE during treatment, AE concentrations of 839 μg/L, 0.46 μg/L and 10.6 mg/kg were respectively found in the inlet, outlet and sludge samples. AE removals of each ethoxymer in the plant were in the range 99.6–100% and no difference was observed between high or low-mole ethoxymers and between AE with odd or even carbon chain lengths. An overall 99.7% removal was also determined on the mass balance of AE in the inlet, the outlet, and sludge of the plant.     

一次溶样原子吸收光谱法检测地质样品银、铜、铅、锌的方法研究

通过实验探讨了一次溶样原子吸收光谱法检测地质样品中银、铜、铅、锌的有关问题的方法研究,改变了原来的分别溶样定容即操作繁琐浪费资源又延长了周期,而是采用一次王水溶样定容,达到了降低成本、简便、快速、准确的宗旨。     

气相色谱法测定煤化工废水中酚类和脂肪酸的实验研究

建立了直接测定煤化工废水中酚类和短链脂肪酸的气相色谱分析方法,该法采用强极性毛细管柱,对脂肪酸和酚同时进行分析测定,用外标法进行定量计算。煤气化废水水样中各物质检出限在3 mg/L~10mg/L,标准曲线在考察质量浓度范围(0.01 g/L~10 g/L)内呈线性关系,相关系数在0.999 7以上,相对标准偏差≤7%。该方法无需复杂的前处理,操作简单易行,测定结果准确。     

多菌灵和菌核净二元混配制剂的分析方法研究

采用反相高效液相色谱外标法对多菌灵、菌核净分别进行定量。方法的标准偏差多菌灵为0.089,菌核净为0.066;变异系数多菌灵为0.45%,菌核净为0.93%;回收率多菌灵为99.63%～100.44%,菌核净为99.17%～100.98%。     

铅火试金富集—发射光谱法测定化探样品痕量金、铂和钯

试样用铅火试金富集铂组元素及金,加入1 mg银,在950℃熔融得到含贵金属的铅扣。铅扣与熔渣分离后在900℃灰吹得含铂、钯和金的银合金粒。把合金粒装入电极,以发射光谱法同时测定铂、钯和金的含量。     

化学原子化器AAS测定生活污水中痕量砷和铅的研究

一般原子吸收法对成分复杂样品中痕量As、Pb元素测定较为困难。微型化学原子化器-原子吸收光谱法因其特殊的机理和结构,通过对介质酸度、NaBH4、载气流速等影响因素的优化,可直接测定生活污水中的As和Pb。相较于一般氢化发生器优点在于快速,成本低,干扰性小,不需要用HCl和NaBH4作载流,NaBH4的消耗可以节省90%以上。     

Characterization of Differences in Flavor in Virgin Rapeseed Oils by Using Gas Chromatography–Mass Spectrometry,Electronic Nose,and Sensory Analysis

Flavor profiles of virgin rapeseed oils (VROs) are comparatively studied for the discrimination and authentication of various flavor types by using gas chromatography–mass spectrometry (GC‐MS), electronic nose (E‐nose), and sensory analysis. The relative odor activity values (ROAVs) of key odorants detected by GC‐MS and E‐nose data are visualized to discriminate VROs with various flavors by using multivariate analysis. The correlation of sensory data, ROAVs of key odorants, and E‐nose data is analyzed. Results show that 47 key odorants comprising aldehydes, isothiocyanates, nitriles, pyrazines, ketones, acids, and alcohols are identified based on their ROAVs. The VROs are divided into three groups and the flavor type of each group is determined, namely, green‐pungent, nutty, and oxidized oil flavor by the three techniques. The above flavor types are mainly attributed to the contributions of isothiocyanates, pyrazines, and aldehydes, respectively, according to the compounds' ROAVs. The correlation of the three techniques is investigated by partial least squares regression: GC‐MS data are confirmed to have good correlation with sensory data. Practical Applications: VROs are characterized by their intense flavor and consequently receiving growing interest among consumers. In this study, different flavor profiles of VROs were comparatively studied using GC‐MS, E‐nose, and sensory analysis. It is found that 47 volatile compounds including aldehydes, isothiocyanates, nitriles, pyrazines, ketones, acids, and alcohols were the key odorants to VRO flavors. The VROs were divided into three types by the three techniques, that is, green‐pungent, nutty, and oxidized oil flavor. The three flavor types were attributed to the contributions of isothiocyanates, pyrazines, and aldehydes, respectively, based on the compounds' ROAVs and GC‐MS was confirmed to have good correlation with sensory data. Although E‐nose cannot correlate all flavor types in the oils, this technique is rapid and low‐cost for VRO discrimination according to various aroma characteristics. GC‐MS and E‐nose can be regarded as potential techniques for flavor discrimination in VROs.     

固相微萃取-气相色谱串联两级质谱法测定水中10种藻类代谢产物

文中建立了固相微萃取-气相色谱串联两级质谱法测定地表水中的10种藻类代谢产物的含量,研究了萃取时间、萃取温度、萃取剂量、萃取纤维等预处理参数对嗅味物质含量的影响,同时对不同规格的色谱柱进行分离效果比较。结果表明,在萃取时间为25 min、萃取温度为65℃、氯化钠含量为1.7 g的测定条件下,采用50/30μm DVB/CAR/PDMS萃取头进行预处理,HP-5MS色谱柱进行分离,质谱检测器进行测定,可以使检测结果达到最优效果。方法的质量浓度均达到5.00～100.00 ng/L,工作曲线回归方程的相关系数R²>0.995;方法检出限(2S/N)为0.14～1.00 ng/L。在纯水加标量为20.00、50.00、80.00 ng/L时,平均回收率为92.0%～109.0%,精密度RSD为0.4%～8.9%,实际水样加标的平均回收率为83.9%～101.8%。该方法检测浓度数量级在纳克级,灵敏度较固相萃取-气相色谱-质谱法提高1 000倍,更适合地表水和饮用水中低浓度藻类代谢产物的检测要求。