电感耦合等离子发射光谱法同时测定茶叶中的七种微量元素

茶叶中微量元素的测定比较常见的有分光光度法,原子吸收光谱法和离子选择电极法等, [1]这些方法往往灵敏度较低,对于多元素的测定需要几种方法联用、费时费力.本文采用电感耦合等离子发射光谱法(ICP)同时测定了茶叶中的七种微量元素,具有灵敏度高、线性范围宽、元素之间相互干扰少,稳定性好等优点.分析速度快、多种元素同时测定只需 1 min左右,方法的相对标准偏差小于2.6%.     

白酒中多种金属元素同时测定-ICP-AES法

首先简要介绍了白酒中金属元素检测的意义，然后通过实验说明了采用等离子发射光谱法(ICP-AES)同时测定白酒中的多种金属元素是非常有效和准确的。     

ICP—AES测定卷烟烟气中钾、钠金属离子

建立了全谱直读电感耦合等离子发射光谱法(ICP–AES),同时测定了其中卷烟烟气中钾钠离子的含量。研究了元素分析标准曲线、精准度、回收率以及不同种类烟草样品中两种离子的含量差别。结果表明,在选定的波长下测定,元素间也没有干扰.该方法快速,准确可靠,加标回收率为95~98%,相对标准偏差RSD均小于4%,适用于对卷烟主流烟气的检测。     

电感耦合等离子原子发射光谱法在皮革检测中的应用

分析了电感耦合等离子原子发射光谱法在分析检测中的优点,并进一步指出了它在皮革中的应用前景。     

电感耦合等离子发射光谱法同时测定连云港产草莓中的铅铬镉铜

采用干法、湿法及微波消解分别处理5个品种草莓样品,全谱直读电感耦合等离子体原子发射光谱法(ICP-AES)同时测定试样中铅、铬、镉、铜微量元素含量并与国标限量进行比较,同时对方法学进行考察。结果表明,5种草莓品种的重金属含量在国标限量范围内,干法、湿法、微波-ICP-AES的加标回收率分别为85.3%～104.5%、94.3%～104.6%、99.8%～106.3%,除个别值外,RSD均小于20%。可以得出结论,干法、湿法、微波-ICP-AES均适合草莓铅、铬、镉、铜含量的测定,方法简便、准确,精密度好,可用于草莓中铅、铬、镉、铜的快速检测;5种品种草莓中的重金属含量未超标。     

废水中六价铬含量的常用测试方法研究

采用等离子发射光谱法(ICP)、分光光度法等不同方法测定了不同溶液中的Cr6+含量,并通过相对误差和加标回收率2种标准对比了各种方法的测试精度.结果表明:ICP测试简单、准确,但成本高,适用于测试结果要求高,特别是微量及痕量测试时使用;分光光度法测试精度较高,可作为快速测试方法使用,其中DPC法在铬含量0.5～2.0mg/L时较准确,过氧化钠和EDTA法在铬含量10 mg/L左右误差较小;测试废液中的铬含量时可采用分光光度法进行初步测试,而后再根据浓度范围选择适宜的方法直接进行测试,或稀释后测试.     

电感耦合等离子发射光谱法测定乳制品中的铝含量

目的建立电感耦合等离子发射光谱法测定乳制品中铝的分析方法,并进一步优化样品前处理方法。方法采用微波消解法处理牛奶和乳扇样品,电感耦合等离子发射光谱测定样品中的铝含量,并进行了连续测定7次的精密度实验和加标回收准确度实验。结果铝元素在0～10 mg/L范围内线性关系良好,方法的检出限是0.6 mg/kg,定量限是1.8 mg/kg,其精密度为5.09%～6.05%,加标回收率94%～101.92%。通过测定市售乳制品发现,牛奶中铝含量正常,乳扇中铝含量偏高。结论本方法简便准确,为研究乳制品中金属元素含量提供一定参考。     

燕麦片中微量元素的测定

应用电感耦合等离子发射光谱(ICP-AES)法测定燕麦片中七种微量元素,取得了满意结果,为研究燕麦片的食用价值提供了一定的科学依据。     

等离子光谱法间接测定微量氯的研究

研究了采用电感耦合等离子原子发射光谱(ICP-AES)法测定混凝土外加剂中微量氯的方法.在待测液中加入过量的Ag 标准溶液,通过测定与Cl-定量反应后剩余的Ag 量从而换算出Cl-的含量,对影响其光谱测量的各种因素进行了较为详细的研究,确定了实验的最佳测定条件.结果表明,方法的回收率为94.6%～105.7%,RSD小于4.03%.该法准确、快速、简便,应用于混凝土外加剂中氯元素的测定,结果满意.     

电感耦合等离子体发射光谱法检测废水中重金属离子的研究

电感耦合等离子体发射光谱法是一种检测金属离子种类和含量的先进分析测试技术,具有灵敏度高,干扰少,重现性好,分析效率高等特点。本文针对华南地区大鹏湾地表水和生活污水建立了电感耦合等离子体光谱测定重金属离子的检测方法。结果表明：铁、锰、铜、锌、镍、铬、镉、铅等金属元素在0.001～1.00 mg/L范围内线性相关性好,所有元素的拟合度r>0.995,该方法检出限范围是0.001～0.011 mg/L,相对标准偏差（RSD）为0.32%～4.09%。该方法操作简便,准确度和精密度较高,可用于地表水和污水中相关金属元素浓度的测定。     

Lead, chromium, tin, iron and cadmium in foods in welded cans

The levels of lead, chromium, tin, iron and cadmium in fruit and vegetables in welded tinplate cans were determined by atomic absorption spectrophotometry. The levels found were compared with those in foods in soldered tinplate cans and fresh foods. The results show that the lead levels in foods in welded cans were much lower than those in similar foods in soldered cans. Foods in unlacquered welded cans contain much more lead, chromium and tin than foods in lacquered welded cans. The cadmium and iron levels in canned fruit and vegetables in welded cans were similar to those found in the corresponding fresh foods.     

Effect of soil moisture stress from flowering to grain maturity on functional properties of Sri Lankan rice flour

Functional properties of flour from rice variety BG 250 (short‐season) and BG 359 (long‐season) exposed to soil water stress from flowering to grain maturity were investigated. Protein content was reduced in both varieties but lipid was reduced only in BG 359 in response to soil moisture stress. AAM content decreased in BG 250 but unaffected in BG 359. Water stress increased swelling power, onset of pasting, peak viscosity, granular breakdown, gel hardness, and cohesiveness in both varieties. Gelatinization temperatures in both varieties were unaffected by water stress, while gelatinization enthalpy was increased in BG 359 but unchanged in BG 250. A double endotherm (type I and type II) appeared in AM–lipid complex in all the flour samples. Type I AM–lipid complex was reduced in BG 359 in response to water stress. Only a single endotherm appeared in the re‐formed AM–lipid complex in gelatinized starch. The magnitude of the ΔH of re‐formed AM–lipid complex was reduced in BG 359 in response to soil moisture stress, but unaffected in BG 250. Water stress decreased AP retrogradation in BG 359 while it was unaffected in BG 250.     

Raising chickens for increased egg consumption in a rural highland Bolivian population

In highland Bolivia a three-year nutrition-sensitive agricultural intervention was carried out with rural families in which chicken rearing was promoted in order to increase egg consumption. Here we report on the impact of the intervention on participants’ diets. The non-randomized intervention took place in 21 rural communities in the province of Tapacarí in the department of Cochabamba, Bolivia. Intervention communities had staggered start times, with two communities starting in 2013, three communities starting in 2014 and sixteen communities starting in 2015. Twenty-four hour dietary recall data were collected from all individuals in 22 households in two communities in February/March 2013, 33 households in three communities in February/March 2014, and 66 households in fourteen communities in February/March 2015. We tested for changes from 2013 to 2014 to 2015 in consumption of 10 food groups in children under 6 years, adult men and adult women. By endline, egg production was established in ~80% of the intervention households. From baseline to endline egg consumption increased to approximately one-half egg/person/day: in children from 7 to 33 g/day, in women from 6 to 33 g/day, and in men from 6 to 39 g/day. Despite the increased intake in eggs, intake of most nutrients did not change. Higher egg consumption would be required to produce observable average increases in nutrient intake.     

Distribution of hydrophilic and lipophilic antibacterial drugs in skim milk,cream, and casein

This study determined the distribution of drugs to different milk fractions according to their physicochemical properties. Hydrophilic drugs tend to concentrate in skim milk, whereas lipophilic drugs tend to concentrate in cream. The concentration of a drug in casein is related to its degree of binding to milk proteins. Thus, we aimed to determine whether withdrawal time in whole milk differs from that in cream, casein, and skim milk. Amoxicillin and tylosin were selected as prototype hydrophilic and lipophilic drugs, respectively. The study was conducted in vitro and in vivo to determine whether in vitro conditions reflect the distribution of drugs in the different milk fractions in vivo. The in vivo study was conducted using a crossover design on 6 healthy Holstein dairy cattle. First, amoxicillin (i.m., single dose, 14 mg/kg) was administered to cows. Following a 1-wk washout period, tylosin (i.m., single dose, 15 mg/kg) was administered. Concentrations of amoxicillin and tylosin in milk and milk fractions were measured using HPLC-UV. In the in vitro study, 0.04 to 400 μg/g of amoxicillin and 0.05 to 50 μg/g of tylosin were spiked to drug-free milk and the concentrations in milk and milk fractions were measured. In addition, the percentage of total protein in milk and milk fractions was determined. Amoxicillin accumulated more in skim milk than in cream and casein, both in vitro (92%) and in vivo (73%, skim milk-to-whole milk ratio). The distribution of tylosin in whole and skim milk was similar to that of amoxicillin in the in vitro study, in contrast to the accumulation of tylosin in cream seen in vivo. However, the accumulation ratio of tylosin in cream was lower than expected. By either method, tylosin was less concentrated in casein than in skim milk and cream. The percentage of total protein was similar in skim milk and whole milk and higher than in cream. Thus, amoxicillin accumulates less in cream and casein, suggesting that these fractions would pose a lower risk to the consumer. Tylosin was still present at the maximum residue limit (50 μg/kg) 24 h after injection in the casein fraction and 48 h after injection in the cream fraction.     

Evaluation of the importance of the digestibility of neutral detergent fiber from forage: effects on dry matter intake and milk yield of dairy cows

Effects of the digestibility of neutral detergent fiber (NDF) from forage on performance of dairy cows were evaluated statistically using treatment means for 13 sets of forage comparisons reported in the literature. All comparisons reported significant differences in NDF digestibilities of forages in situ or in vitro. Treatment means were blocked by study or by additional factorial treatment within a study to remove variation among experiments. The statistical model included random effect of block, fixed factorial effect of NDF digestibility (high or low), and dietary NDF concentration as a covariate. Enhanced NDF digestibility of forage significantly increased dry matter intake (DMI) and milk yield. A one-unit increase in NDF digestibility in vitro or in situ was associated with a 0.17-kg increase in DMI and a 0.25-kg increase in 4% fat-corrected milk. Differences in NDF digestibility between treatments were greater when measured in vitro or in situ than when measured in vivo. Digestibility of NDF in vitro or in situ might be a better indicator of DMI than NDF digestibility in vivo because forages with high in vitro or in situ NDF digestibilities might have shorter rumen retention times, allowing greater DMI at the expense of NDF digestibility in vivo. Digestibility of NDF is an important parameter of forage quality.     

广州秋季市售生蚝微生物污染状况调查

目的是了解广州秋季市售生蚝微生物污染状况。按照GB／T4789—2003《食品卫生微生物学检验》对样品进行微生物检测,结果发现秋季市售生蚝的微生物污染状况比较严重,菌落总数和大肠菌群指标均出现严重超标,超标率分别达到68％和78％,即使在温度偏低的11月份超标现象仍较严重。所检样品中,弧菌超标更为严重,3个月弧菌的检出率则高达90％。结论是广州市售生蚝的微生物污染状况严重,建议消费者不要生食或使用未煮熟的生蚝。     

Physiological levels of androstenedione and testosterone in some edible tissues from calves, bulls and heifers

The physiological levels of androstenedione and testosterone in muscle, kidney and fat of calves, bulls and heifers were determined by RIA. The androstenedione showed the highest levels in fat and the lowest in muscle tissues. Testosterone showed the same distribution only in male animals, whereas in females the highest levels were in kidney. In fat tissue androstenedione was constantly higher than testosterone in all examined animals. In muscle tissue androstenedione levels were higher than those of testosterone in all female animals and in male calves, whereas testosterone was higher in bulls. Testosterone was the main androgen in kidney tissue in both young and adult animals, irrespective of sex.     

Amino-acid composition of maturing wheat

Amino-acids were determined in hydrolysates of two wheat varieties harvested at various stages of maturity, and in flours milled from the wheat samples. During maturation, the concentration in protein of lysine, aspartic acid, glycine. alanine and valine decreased; and concentrations of glutamic acid and proline increased. Milling of wheat into flour reduced the concentrations of lysine, arginine, aspartic acid, threonine, glycine and alanine. Concentrations of glutaniic acid and proline were higher in flour than in wheat proteins. Concentrations of cationic side-chains in amino-acids were higher in wheat than in flour, and in both decreased with maturity. Total carboxyl and amide groups were higher in flour than in wheat, and their concentrations increased as the wheat matured. About 84% of the dicarboxylic acids were in amide form. Small changes were observed in concentrations of amino-acid residues with hydroxylic or hydrophobic groups, and in cystine.     

Effect of elevated accumulation of iron in ferritin on the antioxidants content in soybean sprouts

Cultivation of soybean sprouts in abiotic stress conditions, resulted from the presence of 5–25?mM FeSO₄ in the culture media, causes a strong overexpression of ferritin. Accumulation of ferritin iron in sprouted seeds germinated in the 20?mM solution of FeSO₄ was 67 times higher than in sprouts germinated in distilled water. The cultivation conditions also influence on another antioxidant content—mainly β-carotene content, which increased 28 times (in sprouts cultured in 10?mM FeSO₄ solution) in comparison to the content in dry seeds. Obtained in stress conditions sprouted seeds contain less tocochromanoles than raw seeds. However, their total tocochromanol content was higher than in sprouted seeds cultured in distilled water in every examined concentration of Fe²⁺. A total antioxidant activity is increased only during culturing in 0–10?mM media, and it is positively correlated to the total phenolic compounds content (r?=?0.8498). We concluded that germination in high abiotic stress also causes the increase in different antioxidants content, not only in ferritin, which is directly involved in the process of iron detoxification.     

Evaluation of arterial digital blood flow in dairy cows with claw horn disruption lesions using Doppler ultrasonography

Vascular changes play an important role in the pathogenesis of claw horn disruption lesions in cattle. The aim of the study was to measure arterial blood flow in the hind limbs of German Holstein cows with claw horn disruption lesions. A 10-MHz linear transducer was used to assess blood flow in the interdigital artery in the dorsal pastern region in the hind limbs of 11 non-lame and 33 lame German Holstein cows in which lameness was scored clinically. Qualitative and quantitative blood flow parameters were compared in affected limbs and unaffected contralateral hind limbs in lame cows and in the hind limbs of lame cows and non-lame cows. A pulsed-wave Doppler signal suitable for analysis was obtained in 78 of 88 limbs (33 affected and contralateral limbs, 22 limbs of control cows). Blood flow curve types 1 and 2 were predominant in the hind limbs of lame cows. Vessel diameter, end-diastolic velocity, and blood flow rate were significantly greater in lame cows than in non-lame cows and were numerically greater in moderately lame cows than in mildly lame cows. The differences in the qualitative and quantitative parameters between lame and non-lame cows were most likely caused by inflammation of the pododerm. The role of weight distribution between the paired hind limbs and the existence of claw horn disruption appeared to have an effect on the differences in local circulation in the affected and unaffected contralateral hind limbs in lame cows.