微波消解-EDTA滴定法测定红土镍矿中氧化镁含量

以盐酸、硝酸、氢氟酸溶解红土镍矿样品,加高氯酸冒烟除去硅和氟,采用六次甲基四胺-铜试剂消除共存离子干扰,在pH=10时,以铬黑T作指示剂,用Na2EDTA标准滴定溶液滴定钙和镁的合量;在pH=12时,以钙羧酸作指示剂,用Na2EDTA标准滴定溶液滴定钙的含量,用差减法求得镁的含量。氧化镁质量分数在5.0%~30.0%范围内,该方法加标回收率为99.4%~100.0%,重复性及再现性方程分别为r=0.005m+0.0899和R=0.0091m+0.3553。此方法适合于测定氧化镁含量在5.0%~30.0%的红土镍矿。     

原子吸收光谱法测定营养盐中钾、钙、铁、锌

营养盐试样用盐酸溶解,采用原子吸收光谱法测定钾、钙、铁、锌。对仪器条件及干扰进行了试验,方法的精密度为2.61%~4.66%,加标回收率为98.3%~101.4%。     

火焰原子吸收法测定油橄榄叶片中的微量元素

以采自四川大凉山的油橄榄叶片作试材,建立油橄榄叶片中钙、镁、铁、锌的测定方法。利用微波消解,火焰原子吸收光谱法分别测定了油橄榄叶片中钙、镁、铁、锌的含量。结果表明:油橄榄叶片(莱星)中钙、镁、铁、锌的含量分别为12.89 mg/g、0.678 4 mg/g、1.096 mg/g、0.148 4 mg/g,该方法的加标回收率为98%~103%,相对平均偏差(RSD)为0.5%~4.3%,准确度和精密度良好。为油橄榄的种植及叶片的开发利用提供了可靠基础。     

采用ICP-OES测定三氯化钌中的钙镁含量

介绍一种采用ICP-OES测定三氯化钌中杂质钙镁含量的方法。利用三氯化钌基体对钙、镁发射光谱信号强度的抑制作用,采用标准加入法克服基体效应测定钙、镁杂质含量,加标回收率为88.8%~101.0%,相对标准偏差为0.11%~1.20%。讨论了ICP-OES的检测条件和基体对测定结果的影响,并提出了消除影响的措施。     

原子吸收光度法分析临沧饮用水中钙、镁元素

分析云南省临沧农村地区饮用水的钙、镁离子浓度.在选定的最佳实验条件下采取火焰原子吸收法.所得钙镁离子的线性回归方程分别为Y=0.0659x+0.0403(R2=0.9965),Y=0.1242x+0.0014(R2=0.9981);钙、镁离子的加标回收率分别在97.1%~103.6%,95.3%~101.4%之间。结果表明:该地区饮用水的钙、镁元素最高浓度为160 mg/kg,属于软水。     

干、湿法消解-火焰原子吸收法测定多种食品中钙元素的含量

经干法灰化、湿式消解两种方法预处理,运用火焰原子吸收法测定多种食品中钙元素的含量。结果表明,钙元素在(1~10)μg·m L-1范围内,线性关系良好,相关系数为0.9932。所测13种食品中,虾皮的钙含量最高,为766.61mg/100g(湿法),香菇的钙含量最低,为5.16mg/100g(湿法)。干法灰化加标回收率在90.20%~103.20%,湿法消解加标回收率在90.50%~104.95%,两者相对标准偏差均小于4%。     

大量Li+存在的卤水体系中容量法测定Ca2+的分析方法研究

在Li 、Ca2 共存的相化学研究中,大量Li 的存在对配位滴定法测定Ca2 易产生较大干扰,致使卤水体系中钙的测定结果产生较大偏离。本文在进一步研究了用三乙醇胺作掩蔽剂消除Li 干扰的实验基础上,对高锂钙比(mLi∶mCa≥5)消除Li 的干扰,首次发现正丁醇-无水乙醇的混合液可有效掩蔽共存Li 的干扰。实验结果表明,该方法可使Ca2 分析结果相对误差不超过0.3%。样品加标回收率为99.90%~100.09%,相对标准偏差<0.2%。     

微波消解-ICP-OES法测定塑料中的钙

采用微波消解技术,电感耦合等离子体发射光谱法(ICP-OES)测定塑料中钙。实验中消解体系为6.0 m L浓硝酸和2.0 m L 30%过氧化氢,实验方法的检出限为2.85 mg/kg,精密度RSD5%,加标回收率为92.1%~108.9%。该方法样品用量少,溶样周期短,测试速度快,适用于塑料中钙含量的快速测定。     

北京中力恒优精细化工有限公司

<正>独家研发,生产、经销的下述产品一、PVC热稳定剂化工原料:1.甘油锌白色细粉,无异味总锌量:40%~42%单甘油钙总钙量:(27±0.5)%双甘油钙总钙量:(18%士0.5)%2.甘油镁总镁量:20%~21%3.新合成水滑石301,总镁量:24%~15%总锌量:10%~12%总铝量:4%~5%二、PVC无毒热稳定剂:结晶水:≤10%4-1.GPS钙锌热稳定剂,总锌量:(12%±0.5)%总钙量:(11%±0.5)%4-2.CZM钙锌镁热稳定剂,总锌量:8%~9%钙镁合量:(18±0.5)%     

火焰原子吸收光谱法测定芥蓝中钙、镁、铜和铁

火焰原子吸收法测定芥蓝中的钙、镁、铜和铁含量,相对标准偏差为1.45%~2.03%,回收率为96.8%~100.1%。结果表明芥蓝含有丰富的微量元素。     

硫酸钙在80℃下不同含量盐酸中的溶解性

采用硫酸钙在盐酸中溶解、结晶的方法制备硫酸钙晶须时,必须提高硫酸钙溶解、结晶效率。在80℃水浴条件下,质量分数为5%的盐酸对硫酸钙溶解效果最好,质量分数为10%的盐酸对硫酸钙溶解效果与5%相近。因此,选用5%~10%的盐酸作为溶剂制备硫酸钙晶须。     

Effect of pH, sulfate and sodium on the EDTA titration of calcium

The ethylenediaminetetraacetic acid (EDTA) titration method limits the measurement of calcium concentration to 50 mg/l in water. However, various acids and salt solutions are used in the investigation of the durability of concrete, and the adaptability of the EDTA titration method to determine the calcium in these solutions must be investigated. Hence, the purpose of this study was to investigate the interfering effects of hydrochloric acid, sulfuric acid, sodium chloride and sodium sulfate on measuring the calcium in the aqueous leaching solutions using the EDTA titration method. The calcium standard solutions were prepared using CaCl₂ with initial pH from −0.8 to 7 and calcium concentration up to 160 mg/l. Sulfuric acid and hydrochloric acid were used to prepare calcium solutions with lower pH. Salt solutions with 3% NaCl and 3% Na₂SO₄ were used to evaluate the interfering effects of salt elements such as sulfate and sodium on the EDTA titration. Results indicated that the EDTA titration method was reliable in measuring the calcium up to 160 mg/l, the maximum concentration investigated in this study, in hydrochloric acid with pH higher than zero and 3% sodium chloride solution. Sulfuric acid with pH higher than zero and 3% sodium sulfate solutions showed 3% to 4% less calcium in the solutions. Acid solutions with pH less than zero showed interference with calcium measurement.     

磷矿酸解液制备硫酸钙晶须工艺研究

首先以盐酸分解磷矿制备酸解液,再通过向酸解液中加入硫酸制备硫酸钙晶须。实验考察了加料时间、搅拌转速、硫酸浓度、硫酸根与钙离子物质的量比、氧化钙质量分数、反应温度对硫酸钙形貌及晶须长径比的影响。采用扫描电镜观察硫酸钙形貌并用Image-Pro-Plus对硫酸钙SEM图进行分析得到硫酸钙晶须的平均长径比。实验得到硫酸钙晶须的最佳制备工艺条件是：加料时间为20 min、搅拌转速为350 r/min、硫酸质量分数为40%、反应温度为70 ℃、硫酸根与钙离子物质的量比为0.2、氧化钙质量分数为5.5%,在此工艺条件下可以得到长径比达到98.84的硫酸钙晶须,且形貌均匀。     

含氟混合酸制取氟化钙的研究

六氟磷酸锂生产企业副产大量混合酸,其主要成分是氟化氢和氯化氢。介绍了利用六氟磷酸锂生产企业副产的含氟混合酸和氯化钙为原料制备氟化钙并副产盐酸的生产工艺,并对工艺条件进行了研究。较佳工艺条件：反应温度为60 ℃,氯化钙溶液质量分数为50%,氯化钙溶液与含氟混合酸采用双向加入法（取含氟混合酸应加量的20%作为底液,将氯化钙水溶液和剩余含氟混合酸以一定的滴加速度同时加入反应器中）。对较佳工艺条件进行了验证实验,所得氟化钙产品质量达到企业一级品标准的要求,副产的盐酸质量分数达到25%以上。工艺流程简单,生产易于控制。     

羟基乙烷磺酸钙的合成及表征

以β-巯基乙醇和H2O2溶液为原料合成了羟基乙烷磺酸（ITA）,用ITA和CaCO3为原料合成了目标产物羟基乙烷磺酸钙[Ca（HOCH2CH2SO3）2.2H2O],其结构经TGA,FT-IR1,H NMR和元素分析表征。利用热重分析研究了羟基乙烷磺酸钙的热分解过程,在动态空气气氛下,其热分解过程分为两个阶段。第一阶段（30~300℃）失重率为11.06%,失重主要由所含结晶水引起,结晶水的个数为2。第二阶段（300~650℃）失重率为46.16%,这一阶段是其主要分解过程。通过红外光谱确定了羟基乙烷磺酸钙的热分解产物为CaSO4。25℃羟基乙烷磺酸钙在水中的溶解度为120g.100g-1。     

高锰酸钾滴定法测定钙片中钙的含量

为了准确测定钙片中钙的含量,建立了高锰酸钾容量滴定法测定钙片中钙含量的方法。实验样品经湿法消化后,在酸性溶液中,钙与草酸生成草酸钙沉淀。沉淀洗涤后,加入硫酸溶解,将草酸游离出来,在70—80℃条件下,用高锰酸钾标准溶液滴定与钙等当量结合的钙含量。测定结果的回收率（R）在98．40％-109．74％。用高锰酸钾滴定法测定钙片中的钙含量,简单、快捷、准确、干扰小。     

二水偏硼酸钙的湿法改性及表征

以硼酸和氢氧化钙为原料,在常温常压下合成六水偏硼酸钙,对合成产物进行了化学成分、X射线衍射分析表征,结果表明产物为单一物相的六水偏硼酸钙(CaO·B2O3·6H2O).在140℃下烘干3h得到二水偏硼酸钙(CaO·B2O3·2H2O).以硬脂酸钠、油酸为改性剂对二水偏硼酸钙进行湿法改性,考察了硬脂酸钠、油酸的用量、改性时间、改性温度等因素对二水偏硼酸钙湿法改性的影响.对改性产物进行了红外光谱、活化指数和接触角表征.结果表明:在硬脂酸钠用量为5％,二水偏硼酸钙在60℃下改性反应60 min,改性产物的活化指数可达95.27％,接触角为106.3°,改性效果明显;在油酸用量为5％,二水偏硼酸钙在90℃下改性反应90 min,改性产物的活化指数可达到95.79％.     

Cholelithiasis in hamsters: Effects of cholic acid and calcium on gallstone formation

Dietary cholic acid (0.1%) and/or calcium (2.6% as calcium carbonate) were added to a semipurified diet containing cholesterol and ethynyl estradiol to determine whether the incidence of pigment and/or cholesterol gallstones would be changed. Male golden Syrian hamsters were fed the experimental diets for 96 days (Group 1, control; Group 3, cholic acid plus calcium) or only an average of 60 days (Group 2, 0.1% cholic acid). Animals in Group 2 became ill (weight loss, low food intake, diarrhea) possibly due to cholic acid (or deoxycholic acid) toxicity. Cholesterol gallstones and crystals were absent in all experimental groups. The incidence of pigment gallstones was: control, Group 1, 12/16; 0.1% cholic acid, Group 2, 3/13; and 0.1% cholic acid plus calcium, Group 3, 11/22. Cholic acid with or without calcium produced an elevation of both liver and plasma cholesterol: Group 2, 80.1 mg/g and 501 mg/dl; Group 3, 103.7 mg/g and 475 mg/dl vs Group 1, 65 mg/g and 209 mg/dl, respectively. The lithogenic indices of the bile were lower in Groups 2 and 3 compared to Group 1, controls, 0.45 and 0.58 vs 1.16, respectively. The extent of the portal tract pathology could not be correlated with the presence or absence of pigment gallstones or with the levels of lithocholic acid in the hamster bile. In summary, when semipurified diets were supplemented with ethynyl estradiol and cholic acid, with and without calcium supplementation, no cholesterol gallstones formed and the incidence of pigment gallstones was not altered.     

硝酸磷肥生产新工艺研究

结合中国中品位磷矿特点,提出一条新的制备优级品硝酸磷肥的工艺路线。重点解决了工艺中存在的两个关键问题,即酸解液的过滤和钙离子的去除。针对过滤环节选用磷石膏作为助滤剂来提高酸解液的过滤强度;针对除钙环节,采用两次除钙工艺,首先通过冷冻结晶的方法除掉大部分钙离子,再添加少量硫酸达到产品所需的除钙率。以湖北某磷矿为原料,对该工艺进行了系统研究。在硝酸用量为105%、硝酸质量分数为55％、结晶时间为 4 h、结晶终点温度为0 ℃的工艺条件下,一次除钙率达到73.17%,再加入硫酸进行二次除钙,除钙率达到85.25%,制得符合GB/T 10510-2007《硝酸磷肥、硝酸磷钾肥》的优级品硝酸磷肥。     

Effect of the composition ratio of pimelic acid/calcium stearate bicomponent nucleator and crystallization temperature on the production of β crystal form in isotactic polypropylene

The influence of the composition ratio of pimelic acid/calcium stearate bicomponent nucleator on the β crystal form content of isotactic polypropylene (iPP) had been studied at the crystallization temperature of 120°C and duration of 30 min. It was found that the β crystal form content increased continuously with increasing amount of calcium stearate at the constant amount of 0.15% pimelic acid. High β crystal form content polypropylene could be produced when the amount of calcium stearate was greater than 0.30% (the mass composition ratio of pimelic acid/calcium stearate was less than 1/2, the mole ratio was less than 1.89/1). It was shown that pimelic acid and calcium stearate could react to produce a high effective β nucleator (calcium pimelate) “in situ” during the melt‐mixing of iPP and the bicomponent nucleator. The influence of crystallization temperatures (100–140°C) on the β crystal form content of iPP had also been studied at the constant composition ratio of 0.15% pimelic acid/0.5% calcium stearate (the calcium pimelate produced in situ was 0.16%, which was calculated from stoichiometry). It was found that the β crystal form content increased continuously with increasing crystallization temperature and it maximized at 130°C. β Crystal form content decreased sharply at the crystallization temperature of 140°C. It was shown that β → α modification transformed between 130 and 140°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008