蔬菜搭配与微量元素

人们都想了解和掌握必需微量元素和宏量元素含量配合较为均衡的蔬菜。根据专家们的研究发现,在人们食用的蔬菜中,含人体必需宏量元素和微量元素适量同时较为均衡的蔬菜有20多种,它们是：白萝卜、胡萝卜、小白菜、小青菜、油菜、蕹菜、白茱苔、蒜苗、油角豆、马兰头、韭菜、苦瓜、芪椰菜、莴苣笋（茎）、山药、芦笋、蒜苔、藕、红辣椒、青辣椒等,这些蔬菜所含的人体必需微量元素如：Fe、Me、Zn、Cu、Se等和人体必需宏量元素如K、Na、Ca、Mg等都是中等量,并且含量都是比较均衡,为人们日常调配饮食,购买、     

《化学分析计量》投稿须知

<正>1报道范围分析测试技术,计量行业的法规、政策、标准,标准物质的研制及应用,分析、计量仪器的新产品、新技术、新方法,仪器检定、使用、维修经验,相关专业管理技术、文献综述、专题讲座、专题评论、发展动态及相关信息等。2投稿要求(1)文章重点突出,条理清楚,语句通顺,文字简练,数据可靠,结论恰当,避免重复、繁琐,不用口语、俗语等。全文包括图表在内字数一般在5 000~10 000字为宜。(2)题名应准确、简洁、鲜明,一般不超过20个汉字。作者单位包括全称、所在地、邮编。若作者出自多个单位,应按作者标注的顺序分别列出,在各自单位名称前加"1."",2."",3."。     

动能歧视-电感耦合等离子体质谱(ICP-MS)法测定凉皮中多种元素

为快速、准确定量凉皮中多元素含量,采用微波消解法对凉皮样品进行消解处理,优化了ICP-MS仪器参数条件,选择适合的内标元素,运用动能歧视技术(KED)降低质谱干扰,利用微波消解-电感耦合等离子体质谱(ICP-MS)法测定凉皮中K、Ca、Mg、Be、V、Cr、Ni、As、Se、Mo、Ag、Cd、Sn、Pb、B、Al、Mn、Fe、Co、Cu、Ba及Hg等22种元素含量,各元素相关系数均大于0.995。通过对方法的线性范围、检出限、准确性、稳定性、加标回收率的考察。结果表明,KED-ICP-MS法测定凉皮中各元素的相对标准偏差(RSD,n=6)在0.60%～8.1%,方法加标回收率(n=6)在74.1%～120%,标准曲线线性关系良好(R²=0.995～0.999)。方法具有简便、快速、灵敏、准确的特点,适用于凉皮中多元素的高通量检测。     

油页岩中微量元素赋存形态的研究

通过浮沉实验及脱灰实验对抚顺、龙口、茂名3种油页岩样中部分微量元素进行了赋存形态的研究。结果表明,浮沉实验所得微量元素的赋存状态结果与脱灰实验基本一致,抚顺、龙口、茂名3种油页岩中大部分微量元素以无机态赋存,但也有所区别,抚顺、龙口、茂名油页岩中的元素V、Mn、Zn、Sr、Mo、Ta以及抚顺油页岩中的Cr、Te,龙口油页岩中的Cd、Sn,茂名油页岩中的Cd、Sn、Pb,主要赋存于无机矿物中;茂名油页岩中的Cr、Te,抚顺油页岩中的Cd,龙口油页岩中的Pb有相对较多的比例富集于有机质部分;龙口、茂名油页岩中的元素Co,抚顺油页岩中的Co、Sn、Pb,更多地富集于黏土矿中,但也有少部分富集于有机质中。     

微波消解-高分辨电感耦合等离子体质谱(HR-ICP-MS)法测定原油中22种微量元素

准确测定原油中微量元素含量,对研究原油地球化学,揭示原油原产地信息,具有重要意义。本文采用HNO3微波消解原油样品,优化了样品质量、消解试剂、消解程序等微波消解条件,研究了原油中B、Mg、Al、P、Ti、Ca、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Ga、As、Sr、Mo、Cd、Sn、Ba、Pb共22种微量元素在低、中、高分辨率下的质谱干扰及校正方法,采用高分辨测定Ca,中分辨测定P、V、Cr、Mn、Fe、Ni、Cu、Cd、Co、Sr,低分辨率模式测定其余元素,建立微波消解-高分辨电感耦合等离子体质谱测定原油22种元素的方法。在优化的实验条件下,22种元素的线性相关系数均大于0.999,方法检出限为0.0002μg/g~0.07μg/g。选择原油多元素均质标准品（ConostanS-21）进行方法验证,B、Mg、Al、P、Ti、Ca、V、Cr、Mn、Fe、Ni、Cu、Zn、Mo、Cd、Sn、Ba、Pb元素测定结果的相对标准偏差为0.20%~2.80%,测定值与标准值基本一致;选择巴西原油、安哥拉原油、喀麦隆原油、尼日利亚原油进行Co、Ga、As、Sr元素加标回收试验,加标回收率为95.3%~104.3%,测定结果的相对标准偏差为0.2%~2.3%。选取巴西原油、安哥拉原油、喀麦隆原油、尼日利亚原油进行22种元素测定,分析了不同产地原油的元素含量差异。本方法能够应用于原油中多种微量元素的同时测定,灵敏度高,选择性好,检出限低,结果准确可靠,可为原油地球化学研究提供技术支持。     

电感耦合等离子体发射光谱法测定高纯稀散金属中杂质元素研究进展

综述了电感耦合等离子体发射光谱法测定高纯稀散金属中镓、铟、铊、锗、硒、碲、铼中杂质元素的研究进展,分析了样品测定过程与重点,分别对镓、铟、铊、锗、硒、碲、铼进行了介绍,重点讨论了基体的干扰和消除,并对测定高纯稀散金属中杂质元素的发展方向提出建议。     

电感耦合等离子体质谱法(ICP-MS)测定油品中铁、铜、铅、锡、砷、银、铬、镍、钒

用电感耦合等离子体质谱法(ICP-MS)测定油品中痕量元素铁、铜、铅、锡、砷、银、铬、镍、钒.油品于铂金坩埚中,在马弗炉内进行亚沸加热,首先蒸发除去有机物质直至仅剩余无机物残渣,然后在500℃灼烧灰化残渣,再加入硝酸、过氧化氢在电热板上加热浸取消解反应至完全,并煮沸分解过氧化氢,彻底消除了有机物对质谱测定的影响,试液组...     

生物质气化发电厂灰渣中微量元素的分布与富集规律

采用电感耦合等离子体发射光谱仪,研究了生物质气化发电厂灰渣中元素As、Al、Br、Ca、Cd、Cl、Cr、Cu、F、Fe、Ga、K、Mg、Mn、Na、Ni、P、Pb、S、Si、Sr、Ti、Zn在气化器底灰、淋洗器灰和旋风分离器灰中的质量分数,并分析了这些元素在不同粒径3种灰渣中的分布规律。结果表明,大部分极易挥发的元素,如卤族元素、碱金属元素主要在淋洗器中存在,表明了它们在飞灰颗粒中的富集。旋风分离器灰在灰渣中所占比例为10%左右,以粗灰为主,灰中Fe、Si、Ni、Pb、Zn、Cr、Cd为多;表明了此灰中重金属元素积累。在气化炉底灰中以K、S、Mn、Cu为主。元素随颗粒物粒径大小和元素性质的不同,呈现不同的富集规律。     

《化学分析计量》征稿启事

<正>《化学分析计量》由中国兵器工业集团第五三研究所主办,是全国性分析测试、化学计量专业技术刊物,中国科技核心期刊,中国学术期刊综合评价数据库统计源期刊,中国仪器仪表学会分析仪器分会会刊,中国石油和化工行业优秀期刊,中国兵器工业优秀期刊,华东地区优秀期刊,入选美国CA千种表。国内统一刊号:CN 37–1315/O6,国际标准刊号:ISSN 1008–6145。双月刊,大16开本。单月20日出版。征稿范围:分析测试技术,计量行业的法规、政策、标准,标准物质的研制及应用,分析、计量仪器的新产品、新技术、新方法,仪器检定、使用、维修经验,相关专业管理技术、文献综述、专题讲座、专题评论、发展动态及相关信息等。投稿要求:(1)文章重点突出,条理清楚,语句通顺,文字简练,数据可靠,结论恰当,避免重复、繁琐,不用口语、     

深情怀念中国科学院院士徐僖先生北大核心CSCD

徐僖先生是中国共产党党员,忠诚的爱国主义者,九三学社社员,杰出的科学家,中国科学院院士、英国皇家化学会会士,我国高分子材料学科的开拓者和奠基人之一,第三、五、六、七、八届全国人大代表,     

绿豆萌发过程中SOD的分离纯化及性质研究

制备不同萌发时期绿豆SOD(超氧化物歧化酶)粗酶液,筛选出酶比活力最高的时期,并运用热变性、硫酸铵分级、DEAE-Sepharose FF阴离子交换层析和Sephacryl S-100 HR分子筛层析分离纯化并作对比考察,提纯的SOD进行了理化性质研究。结果表明,绿豆种子萌发第3天时SOD的比活力最高,经纯化获得的SOD酶比活力为2256.4 U/mg,纯化倍数为3.9。绿豆中SOD为Cu/Zn SOD和Mn SOD,分子量为68KD,热稳定性高,在pH5-8条件下稳定,对高浓度SDS具有抗性。EDTA可以一定程度上抑制SOD活性,H2O2可以完全抑制SOD活性。     

Purification and Characterization of a Cu,Zn-SOD from Garlic (Allium sativum L.). Antioxidant Effect on Tumoral Cell Lines

Crude garlic extract contains one Mn-superoxide dismutase designated as SOD1 and two Cu,Zn superoxide dismutases as SOD2 and SOD3. The major isoform SOD2 was purified to homogeneity by Sephacryl S200-HR gel filtration, DEAE Sepharose ion exchange chromatography, and chromatofocusing using PBE 94. SOD2 was purified 82-fold with a specific activity of 4,960 U/mg protein. This enzyme was stable in a broad pH range from 5.0 to 10.0 and at various temperatures from 25 to 60°C. The native molecular mass of SOD2 estimated by high performance liquid chromatography on TSK gel G2000SW column was 39 kDa. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis showed a single band near 18 kDa, suggesting that native enzyme was homodimeric. The isoelectric point as determined by chromatofocusing was 5. Analysis of its N terminal amino acid sequence revealed high sequence homology with several other cytosolic Cu,Zn-SODs from plants. Exposure of cancer cell lines to garlic Cu,Zn-SOD2 led to a significant decrease in superoxide content with a concomitant rise in intracellular peroxides, indicating that the enzyme is active in mammalian cells and could, therefore, be used in pharmacological applications.     

Clone,Purification and Characterization of Thermostable Aminopeptidase ST1737 from Sulfolobus tokodaii

The aminopeptidase gene from thermophilic archaea Sulfolobustokodaii was cloned and expressed in Escherichia coli BL21 codon-plus(DE3). To overexpress the aminopeptidase, the vector pET32a was constructed, in which the target gene was fused with the genes of histidine-tag and thioredoxin(Trx). The expressed protein was purified using Ni²⁺-column affinity chromatography and ion exchange chromatography and cleft with enterokinase(EK) to obtain the purified aminopeptidase(ST1737). The biochemical and enzymic properties of the expressed ST1737 were characterized. The results show that its optimal pH and temperature are 8 and 80 ℃, respectively. The half-life of ST1737(0.2 mg/mL) is about 85 h at 90 ℃, indicating that the enzyme exhibits an excellent thermostability. The activity of ST1737 could still maintain over 85% after its treatment at 25 ℃ in different buffers with a pH range of from 6.0 to 10.5 for 24 h, demonstrating that ST1737 is stable in neutral or slight alkali environment. The enzyme shows a high activity for the substrates, such as unmodified peptide Asp-Ala, while the pNPC₈ shows an optimal esterase substrate specificity. These results indicate that the enzyme is a bifunctional enzyme, and different from the aminopeptidase reported before.     

Purification and Characterization of Superoxide Dismutase （SOD） from Camellia Pollen

A superoxide dismutase（ SOD ） was purified to homogeneity from fresh camellia pollen by means of ammonium sulfate precipitation and column chromatography with DEAE-cellulose（ DE52 ）, Sephadex G-100 and phenyl sepharose^TM 6 Fast Flow columns. Its specific activity could reach to 4034 U/mg protein and it was determined to be Cu/ Zn-SOD according to its different sensitivities to different inhibitors. The molecular weight of the SOD and its subunit were 69500 and 34700, respectively, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS- PAGE）, which implicates that the SOD in camellia pollen is a dimmer composed of two identical subunits. The isoelectric point of the enzyme was determined to be 4. 1 by isoelectric focusing electrophoresis and the N-terminal amino acid was identified to be Gly by the DNS-Cl method. Its α-Helix was also calculated to be approximately 21.8% according to the circular dichroism（CD） spectra.     

Purification and characterization of thermostableD-hydantoinase from thermophilicbacillus stearothermophilus SD-1

A thermostable D-hydantoinase of thermophilicBacillus stearothermophilus SD-1 was purified to homogeneity using an immuno-affinity chromatography. The affinity chromatography that employed polyclonal antibody immobilized on Sepharose 4B was simple to operate and gave a purification yield of 60% of enzyme activity. Molecular mass of the enzyme was determined to be about 133.9 kDa by gel filtration chromatography and the molecular mass of the subunit was 54 kDa on SDS-PAGE. Mass spectrometric analyses were also performed for the determination of the molecular mass of the native enzyme and its subunit. The apparent molecular masses were 51.1 and 102.1 kDa for the subunit and native enzyme, respectively. Based on the molecular masses determined by these two methods, it is suggested that the D-hydantoinase exists as a dimeric conformation in the cell. Isoelectric pH of the enzyme was observed to be 4.47. It was found that the enzyme requires one manganese ion per molecule of enzyme for the activity. The optimal pH and temperature for the catalytic activity were about 8.0 and 65‡C., respectively. The half-life of the enzyme was estimated to be 30 min at 80‡C., confirming that the enzyme purified is one of the most thermostable D-hydantoinase reported so far. Kinetic constants of the enzyme for different substrates were also determined.     

Zinc deficient bovine erythrocyte superoxide dismutase has low specific activity.

Zinc deficient bovine superoxide dismutase (Cu2E2SOD (E = empty)) was prepared and purified by high performance liquid chromatography (HPLC). Each peak was characterized as to protein, copper content and specific activity. The Cu2E2SOD peak fractionated by HPLC has a low specific activity at pH 7.8 (about 10% of the native enzyme (Cu2Zn2SOD)). With the addition of zinc ions, the specific activity of Cu2E2SOD was quantitatively restored to that of the native enzyme. This behavior implies that the zinc ion is very important for the appearance of enzyme activity.     

Purification and Characterization of an Ethanol-Tolerant β-Glucosidase from Sporidiobolus pararoseus and Its Potential for Hydrolysis of Wine Aroma Precursors

An extracellular ethanol-tolerant β-glucosidase from Sporidiobolus pararoseus was purified to homogeneity and characterized, and its potential use for the enhancement of wine aroma was investigated. The crude enzymatic extract was purified in four steps (concentration, dialysis, ultrafiltration, and chromatography) with a yield of around 40 % for total activity. The purified enzyme (designated Sp-βgl-P) showed a specific activity of approximately 20.0 U/mg, an estimated molecular mass of 63 kDa after sodium dodecyl sulfate polyacrylamide gel electrophoresis, and isoelectric point of 5.0 by isoelectric focusing. Sp-βgl-P has optimal activity at pH 4.0 and at 55 °C. It was stable in a broad pH range at low temperatures and it was tolerant to ethanol and glucose, indicating suitable properties for winemaking. The hydrolysis of glycosidic terpenes was analyzed by adding Sp-βgl-P directly to the wines. The released terpene compounds were evaluated by gas chromatography/mass spectrometry. The enzymatic treatment significantly increased the amount of free terpenes, suggesting that this enzyme could potentially be applicable in wine aroma improvement.     

Purification and characterization of thermostable d-hydantoinase from Bacillus thermocatenulatus GH-2

A thermostable D-hydantoinase was isolated from thermophilic Bacillus thermocatenulatus GH-2 and purified to homogeneity by using immunoaffinity chromatography. The molecular mass of the enzyme was determined to be about 230 kDa, and a value of 56 kDa was obtained as a molecular mass of the subunit on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, implying that oligomeric structure of the enzyme is tetrameric. Isoelectric pH of the enzyme was found to be approx 4.3. The enzyme required Mn2+ for the activity and exhibited its highest activity with phenylhydantoin as a substrate. The optimal pH and temperature for catalytic activity were about 7.5 and 65 degrees C, respectively. The half-life of the enzyme was estimated to be about 45 min at 80 degrees C.     

Purification and characterization of an alkaline protease prot 1 frombotrytis cinerea

Alkaline thiol protease named Prot 1 was isolated from a culture filtrate ofBotrytis cinerea. The enzyme was purified by ammonium sulfate fractionation, gel filtration, and ion-exchange chromatography. Thus, the enzyme was purified to homogeneity with specific activity of 30-fold higher than that of the crude broth. The purified alkaline protease has an apparent molecular mass of 43 kDa under denaturing conditions as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native molecular mass (45 kDa), determined by gel filtration, indicated that the alkaline protease has a monomeric form. The purified protease was biochemically characterized. The enzyme is active at alkaline pH and has a suitable and high thermostability. The optimal pH and temperature for activity were 9.0–10.0 and 60°C, respectively. This protease was stable between pH 5.0 and 12.0. The enzyme retained 85% of its activity by treatment at 50°C over 120 min; it maintained 50% of activity after 60 min of heating at 60°C. Furthermore, the protease retained almost complete activity after 4 wk storage at 25°C. The activity was significantly affected by thiol protease inhibitors, suggesting that the enzyme belongs to the alkaline thiol protease family. With the aim on industrial applications, we focused on studying the stability of the protease in several conditions. Prot 1 activity was not affected by ionic strength and different detergent additives, and, thus, the protease shows remarkable properties as a biodetergent catalyst.     

Purification of α-Amylase from Bacillus sp. GHA1 and its partial characterization

Bacillus sp. GHA1 was isolated from water samples and screened for the production of α-amylase. Maximum production of amylase by this strain occurs at 42 °C, pH 6.5 and 72 h after cultivation in production medium. The enzyme was purified through successive applications of ammonium sulfate precipitation, ion exchange and hydrophobic interaction chromatography, resulting in a single band with an apparent molecular weight of 66 kDa, as judged by SDS-PAGE. Calcium analysis of the purified enzyme revealed that it contained three metal ions per molecule. The new extracellular α-amylase is active in a wide range of pH with its maximum activity at pH values 5.5–8.0. The optimum temperature for enzyme activity is 57 °C and the presence of calcium has relatively low influence on its activity and thermostability. The Bacillus sp. GHA1 α-amylase with these properties may be suitable for use in detergent and food industries.