ICP-MS法快速测定餐用纸中金属污染物

建立等离子电感耦合质谱(ICP-MS)配合微波消解法检测餐用纸中铅、镉、砷、铬、镍、钡和锑的含量。样品经硝酸消解,微波程序升温法进行处理,ICP-MS同时测定其中7种金属污染物。结果表明:各元素的线性范围为0~100.0μg/L,标准曲线线性相关性良好,r≥0.999,7种元素方法检出限为0.003~0.243 mg/kg,加标回收率在90%~115%之间。样品前处理安全性高,消化过程方便易于控制,检测方法精密度高(RSD5%),实现了多元素同时快速测定,可用于食品接触用纸金属元素监测。     

混合基体改进剂-石墨炉原子吸收光谱法测定 速溶茶中的铅镉铬

目的以微波消解为前处理方式,建立一种石墨炉原子吸收光谱法测定速溶茶中微量重金属铅、铬、镉的实验方法。方法采用高压密闭微波消解仪对速溶茶进行消解,加入硝酸铵、硝酸钯等基体改进剂消除样品干扰,并优化仪器条件进行石墨炉原子法测定。结果测定速溶茶中铅、铬、镉的最佳基体改进剂分别为硝酸铵-硝酸钯混合基体改进剂、硝酸钯基体改进剂、硝酸铵-硝酸钯混合基体改进剂。在最佳实验条件下,铅、铬、镉的线性范围分别为0~80μg/L、0~40μg/L、0~2μg/L,检出限分别为0.3681μg/L、0.1268μg/L、0.0076μg/L,铅、镉、铬的标准曲线相关系数分别为0.9990、0.9978和0.9992,回收率均在98.64%~101.9%之间,样品测定相对标准偏差均小于5%。结论该方法简便、快速、准确,可作为速溶茶中铅、镉、铬快捷、可靠的检测方法。     

自动石墨消解-电感耦合等离子体质谱法监测干制水产品中的铅、砷、铝、铬、铁、铜

为建立同时检测干制水产品中铅、砷、铝、铬、铁、铜金属残留的电感耦合等离子体质谱(Inductively coupled plasma mass spectrometry,ICP-MS)方法。选择自动石墨消解仪对样品进行消解,消解完全后,利用ICP-MS对样液进行检测,内标法定量分析。结果显示:铅、砷、铝、铬、铁、铜元素浓度在0. 25～25μg/L范围内线性良好,相关系数(R2)均大于0. 990;检测限:铅0. 02μg/L、砷0. 08μg/L、铝0. 12μg/L、铬0. 10μg/L、铁0. 03μg/L、铜0. 05μg/L;加标回收率在84. 0%～108. 4%之间;方法重复性RSD(n=6)低于10%。该方法操作简单、准确度高、检测限低、重复性好,可以用于干制水产品中的金属元素检测。     

自动石墨消解-电感耦合等离子体质谱法同时测定发酵面制品中的铅、砷、镍、铝、铬

目的建立自动石墨消解-电感耦合等离子体质谱法同时检测发酵面制品中的铅、砷、镍、铝、铬元素。方法采用微波消解技术进行样品消化,电感耦合等离子体质谱仪对消化后的样品进行检测,内标法进行定量分析。结果 5种元素质量浓度在0.2~30μg/L范围内呈现良好的线性,相关系数(r2)均不低于0.995;检出限为铅6.1μg/kg、砷0.32μg/kg、镍5.4μg/kg、铝12.3μg/kg、铬2.4μg/kg;各元素加标回收率在85%~110%之间;重复性相对标准偏差在5.0%以内(n=6)。结论该方法前处理简单、检出限低、重复性好、检测结果准确,可用于发酵面制品中的铅、砷、镍、铝、铬的检测。     

电热消解-石墨炉原子吸收法测定白酒中铅含量的研究

为了更加方便、快速地检测批量白酒中铅的含量,建立了一种蒸发浓缩-电热消解-石墨炉原子吸收法测定白酒中铅的方法。试验结果表明,该方法在0~80.0μg/L范围内呈线性相关,相关系数为0.999 9,检出限为0.41μg/L,样品的加标回收率在90%~110%之间。该方法准确度、精密度良好,能够简便、快速、有效的测定白酒中的铅含量。     

微波消解-电感耦合等离子体质谱法测定坚果中钒、钴、钼含量

目的建立微波消解-电感耦合等离子体质谱法同时测定坚果中钒、钴、钼含量的检测方法。方法以纯硝酸体系作为消解液,用微波消解对样品进行前处理,采用电感耦合等离子体质谱仪同时对3个元素进行测定,内标法定量。结果 3个元素均在0~50μg/L范围内线性关系良好,线性相关系数大于0.999,钒、钴、钼的检出限(S/N=3)分别为1.80、1.00、5.40μg/kg。在2.00、20.0、40.0μg/L 3个加标水平下,3个元素的回收率在92%~109%之间,相对标准偏差为4.64%~7.55%。结论此方法前处理简便,检测时间短,且精密度高、准确性好,适用于检测坚果中钒、钴、钼等微量元素。     

电感耦合等离子体质谱法测定云南市售大米中4种有益元素

目的建立石墨湿法消解-电感耦合等离子体质谱法同时测定云南大米中4种有益元素含量的方法。方法以产自云南省12个州市共90件大米为实验对象,采用石墨湿法消解对样品进行前处理,电感耦合等离子体质谱法进行测定,内标法定量分析云南大米中锰(Mn)、铁(Fe)、铜(Cu)、锌(Zn)4种有益元素的含量。结果云南大米中锰、铁、铜、锌4种金属元素在0~100μg/L质量浓度范围内呈现良好的线性关系,相关系数均大于0.999。通过加标回收实验分析锰、铁、铜、锌4种金属元素的加标回收率依次为93.61%~100.37%、88.32%~105.47%、99.91%~101.78%、94.14%~102.89%,相对标准偏差依次为3.37%、1.02%、0.16%、1.18%,4种金属检出率均为100%。结论石墨湿法消解-电感耦合等离子体质谱法精密度好、准确度高,可同时测定大米中多种金属,适用于云南大米中锰、铁、铜、锌含量的测定。     

微波消解-电感耦合等离子体质谱法测定奶粉中的铬

本方法采用微波高压消化仪消解奶粉样品,以电感耦合等离子体质谱法(ICP-MS)测定奶粉中的铬元素含量,同时采用干灰化-原子吸收石墨炉法(国标法)测定样品,与本方法进行比较。实验表明样品浓度、积分时间与响应值呈正相关,当样品中铬的浓度大于10μg/L时,应采用0.1s的积分时间;当铬的浓度小于10μg/L时,应采用高于2.0s的积分时间。实验结果显示该方法与国标法的测定结果相吻合,测得相对标准偏差为0.92%~4.21%,回收率为95.6%~102.2%,在1.0~500μg/L范围内呈良好的线性关系(r=0.9999)。本方法具有操作简单、快速、灵敏度高、抗离子干扰能力强的优点,完全适用于快速准确测定奶粉中的铬元素含量。     

ICP-MS法同时测定云南野生牛肝菌中5种金属元素

建立微波消解-电感耦合等离子体质谱(Inductively coupled plasma-mass spectrometry,ICP-MS)法测定云南省6种常见野生牛肝菌中5种金属元素(总砷、铅、总汞、镉、铬)。采用HNO3和H2O2作为消解酸体系,样品采用微波消解进行前处理,通过ICP-MS法同时测定牛肝菌中5种金属元素的含量。结果表明,总汞在0~48μg/L范围内呈现良好的线性关系,铅、总砷、镉、铬在0~200μg/L范围内呈现良好的线性关系(r0.999),方法的检出限在0.001~0.01 mg/kg,平均回收率为95.22%~100.08%,精密度的RSD小于5%,重复性的RSD均小于2%。建立的方法具有简便、快速、准确度好等优点,可推荐用于食用菌中金属元素的定量测定,并为其质量监控提供参考。     

压力罐消解电感耦合等离子体质谱法同时测定动物肝脏中铬、砷、镉、铅

目的建立压力罐消解电感耦合等离子体质谱法(inductively coupled plasma-mass spectrometry,ICP-MS)同时测定动物肝脏中铬(Cr)、砷(As)、镉(Cd)、铅(Pb)的分析方法。方法采用压力罐消解技术用浓硝酸对样品进行消化,运用电感耦合等离子体质谱法同时测定猪肝、鸭肝、牛肝、羊肝、鸡肝中Cr、As、Cd、Pb 4种元素的含量。结果 4种微量元素线性范围良好,相关系数均大于0.999,各元素相对标准偏差(relative standard deviation,RSD)均小于5.0%(n=6),加标回收率92.0%~105.9%之间,方法检出限为0.00008~0.002μg/g,定量限为0.00024~0.006μg/g。用生物标准参考物质评价分析方法的准确度,测定结果与推荐值相符。结论此方法准确、快速,适用于动物肝脏中微量元素的测定。     

Natural pigments: carotenoids, anthocyanins, and betalains--characteristics, biosynthesis, processing, and stability

Pigments are present in all living matter and provide attractive colors and play basic roles in the development of organisms. Human beings, like most animals, come in contact with their surroundings through color, and things can or cannot be acceptable based on their color characteristics. This review presents the basic information about pigments focusing attention on the natural ones; it emphasizes the principal plant pigments: carotenoids, anthocyanins, and betalains. Special considerations are given to their salient characteristics; to their biosynthesis, taking into account the biochemical and molecular biology information generated in their elucidation; and to the processing and stability properties of these compounds as food colorants.     

卷烟中锂、铬、镍、铜、砷、硒、钼、镉、铊和铅含量分析

采用微波消解-电感耦合等离子体质谱法测定了41个牌号烤烟型卷烟和雪茄烟样品烟丝中的锂、铬、镍、铜、砷、硒、钼、镉、铊和铅含量,并按照类型和价位对卷烟中这10种有害元素含量进行了统计分析。结果发现:①卷烟中锂和铜的含量较高,铊的含量很低,铬、镍、镉、铅、砷、硒和钼7种元素的平均含量为0.55～4.42μg/g;②雪茄烟中铬、镍、砷、钼、镉、铊和铅的含量一般高于烤烟型卷烟,而硒元素的含量则相反,但差别较小;烤烟型卷烟中锂和铜的含量与雪茄烟没有显著差异;③高档卷烟中的锂、镍、镉、铊和铬含量较低,而砷、铅的含量较高;不同价位卷烟的铜、硒和钼含量差异不显著。     

Tyrosinase, Laccase, and Peroxidase in Mushrooms (Agaricus, Crimini, Oyster, and Shiitake)

Enzyme assays and electrophoresis were used to monitor the activity of tyrosinase, laccase, and peroxidase in Agaricus bisporus (common cultivated button mushrooms and Crimini mushrooms), Oyster, and Shiitake mushrooms. The three enzymes could be differentiated using specific substrates and inhibitors. Tyrosinase seemed to be the major phenol oxidase in the Agaricus strains, while Oyster and Shiitake mushrooms had much lower levels. Peroxidase activity was low or undetectable in all types examined. Control of enzymatic browning in different mushroom types may depend upon the distribution of different oxidases within any given type.     

Polyphenols, Anthocyanins, Ascorbic Acid, and Radical Scavenging Activity of Rubus, Ribes, and Aronia

ABSTRACT: Total polyphenols, total anthocyanins, and reduced ascorbic acid were evaluated in berries belonging to the genera Rubus, Ribes, and Aronia by means of spectrophotometric and high-performance liquid chromatography (HPLC) techniques. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the fruit extracts was tested. Total polyphenols ranged from 140.6 to 888.5 mg/100 g fresh weight (FW), total anthocyanins ranged from 22.0 to 460.5 mg/100 g FW, and reduced ascorbic acid ranged from 12.4 to 153.8 mg/ 100 g FW. The average EC50 values for Aronia melanocarpa, Ribes nigrum, Ribes rubrum, Rubus fruticosus, and Rubus idaeus were 1.8, 2.8, 5.3, 6.4, and 8.2 mg FW, respectively. The results indicate that the fruits tested are good sources of natural antioxidants.     

Hormones, metabolites, and reproduction in Holsteins, Jerseys, and their crosses

Holsteins (HH), Jerseys (JJ), and their crosses in first (n=157) and second (n=107) lactation were used to determine if reproduction, progesterone (P4), insulin-like growth factor 1 (IGF-1), insulin, nonesterified fatty acids (NEFA), and milk production differed between genetic groups. Thirty-four cows were Holstein-Jersey (HJ) crosses, 46 were Jersey-Holstein (JH) crosses, 48 were purebred Holsteins (HH), and 29 were purebred Jerseys (JJ) in first lactation, whereas the second-lactation animals included 23 HJ, 35 JH, 35 HH, and 14 JJ. Blood samples were collected weekly for the first 10 wk postpartum. Analyses were conducted using the MIXED, chi-square, and GLIMMIX procedures (SAS Institute Inc., Cary, NC). Seasons of calving were cold (November to May) and hot (June to October) and were combined with year to form 8 year-seasons. Days open and number of services were affected by genetic group. The HH were open 169±8 d, which was greater than HJ (143±9 d), JJ (132±10 d), and JH (127±8 d). The HH had 2.4±0.1 services per pregnancy, which was greater than JH (1.9±0.1), but not different from HJ (2.1±0.2) or JJ (2.1±0.2). Concentrations of NEFA were greater in lactation 2 (0.52±0.02 mEq/L) than in lactation 1 (0.45±0.02 mEq/L) and decreased over the 10-wk period. Concentrations of NEFA were greater in the cold season except in yr 3. Insulin in lactation 1 (0.81±0.03 ng/mL) was greater than in lactation 2 (0.72±0.03 ng/mL); insulin decreased to wk 2 then gradually increased. The HJ had the greatest insulin concentrations (0.87±0.04 ng/mL) and the JJ had the lowest (0.66±0.04 ng/mL), and IGF-1 gradually increased over the 10-wk period. Milk production (actual yield in the first 305 d, not adjusted for fat and protein) was affected by genetic group, lactation number, year-season, and wk 1 insulin. The HH produced 10,348±207 kg of milk, which was greater than the HJ (9,129±230 kg), the JH (9,384±190 kg), and the JJ (7,080±240 kg). Milk production in lactation 2 (9,676±163 kg) was greater than that in lactation 1 (8,294±160 kg). The JJ (10.3±4.7%) had the highest frequency of mastitis. The chance of getting mastitis for HH (1.1±0.9%) differed from that for HJ (9.4±4.1%), JH (8.1±3.4%), and JJ (10.3±4.7%). Genetic group affected hormones and metabolites, which may partially explain differences in reproductive measures and milk yield.     

Water-, oil-, and soil-repellent treatment of textiles,artificial leather,and leather

Several products are on the market to realize water-, oil-, and soil-repellent properties on textiles or textile-related materials. To make an adequate and fast rating of repellent properties of finished textiles, different drop tests according to AATCC and ISO standards are commonly used. For evaluation of the repellent properties of solid substrates against different liquids often contact angle measurements are performed. The aim of the work presented here is to determine and evaluate the repellent effects gained by the application of three different finishing agents on three different substrates, such as polyester fabric, artificial leather, and leather. The main questions are at that point: It is possible to gain similar repellent effects with the same finishing product applied on different substrates? Do the different testing methods lead to comparable results? Is there a relation to the repellency against everyday consumer products as red wine, ice tea, or coffee? This article should help the reader to evaluate different testing methods and the influence on common substrates.     

Capsicum--production, technology, chemistry, and quality. Part V. Impact on physiology, pharmacology, nutrition, and metabolism; structure, pungency, pain, and desensitization sequences

The spice Capsicum is the fruit of the cultivated species of the genus Capsicum (family, Solanaceae), C. annuum principally, and C. frutescens L. to a lesser extent. A third variety of C. annuum var. annuum fruits, the large-sized, fleshy bell capsicum is used as a fresh vegetable and valued for its aroma, color, and crisp texture, but with no pungency. This variety is not considered in this series of reviews covering primary processing, production, international trade, chemistry, and biochemistry of functional components--the red keto carotenoids, the aromatic volatiles and the pungent capsaicinoids in Parts I to III. The valid qualitative aspects correlating the specific components of capsicum and their sensory responses are critically covered in Part IV. In this the concluding part of the series of reviews, the significant preference of the spice for initially evoking an aversive response, its potent physiological and pharmacological effects, and the aspects of structure-activity relationships of the pungent stimuli of the capsaicinoids are reviewed. The beneficial effects particularly associated with long usage by some ethnic groups and its safe consumption levels, with a critical review of the studies on the gastrointestinal tract, the cardiovascular system, the sensory system, thermoregulation, nutritional impacts, and an overview of the five series is also detailed.     

Simultaneous and Direct Determination of As, Bi, Pb, Sb, and Se and Co, Cr, Cu, Fe, and Mn in Milk by Electrothermal Atomic Absorption Spectrometry

Tungsten permanent modifier with coinjection of Pd(NO₃)₂ and W–Ru permanent modifiers are proposed for the direct and simultaneous determination of As, Bi, Pb, Sb, and Se (group 1) and Co, Cr, Cu, Fe, and Mn (group 2), respectively, in milk by graphite furnace atomic absorption spectrometry. The performance of modifiers was evaluated by means of thermal behavior of analytes, sensitivity, atomic signal profile, repeatability, graphite tube lifetime, and background intensity. An air-assisted pyrolysis step was necessary to quantitative elimination of the organic matter. After methods optimization, 14 commercial milk samples were analyzed. The found concentrations of As, Bi, Pb, Sb, Se, Co, and Cr were lower than their limit of detection (2.13, 2.21, 1.49, 1.63, 2.05, 1.0, and 1.2 μg L⁻¹, respectively). Concentrations of Cu, Fe, and Mn were in the 1.58–5.74 μg L⁻¹, 9.79–49.3 μg L⁻¹, and 2.25–4.08 μg L⁻¹ intervals, respectively. The limits of detection for Cu, Fe, and Mn were 1.7, 5.3, and 2.0 μg L⁻¹, respectively. The accuracy of methods was checked after analysis of two milk standard materials. Results for Cr, Cu, Fe, Mn, Pb, and Mn were in agreement with certified values of SRMs at the 95% confidence level. Accuracy was also evaluated by addition–recovery tests and recoveries in the 86–127% range were obtained for all elements. The use of pretreat platform of graphite tubes with W or W–Ru allowed enlarging the lifetime of atomizer in 750 heating cycles.