二安替比林甲烷分光光度法测定铝合金中钛

介绍了采用二安替比林甲烷光度法直接测定铝合金中钛含量的方法。试样经硝酸-氢氟酸快速分解,以硼酸中和过量氢氟酸,在1.2 mol/L盐酸-1.8 mol/L硫酸介质中显色,溶液中大量共存离子均不干扰测定。钛含量在0.40~10.0μg/mL范围内符合比尔定律,线性回归方程为A=0.0106+0.365ρ(μg/25 mL),r=0.9996。方法用于铝合金标准样品中钛的测定,结果与认定值吻合,相对标准偏差为2.5%~5.0%。     

电积分离铜-分光光度法测定铜浸出液中活性硅

铜浸出液中含有大量的铜离子,用硅钼蓝分光光度法测定活性硅时,铜离子的蓝色可严重干扰硅的测定。为了消除铜离子对硅测定的干扰,实验对铜浸出液进行了电积分离铜预处理,并主要考察了电流密度对分离铜的效果、硅钼蓝分光光度法不同波长下的吸光度情况、样品中和后盐酸加入量、电积分离铜后试液中各共存元素等因素对硅测定的影响。结果表明:电积分离铜最佳电流密度为5.0A/dm²;硅钼蓝分光光度法测定活性硅时,最佳测定波长为640nm;样品中和后盐酸(1+9)最佳加入量为6.00mL;分离铜后试液中各共存元素对硅测定无明显干扰。当硅质量浓度在0.05~3.00μg/mL时,硅质量浓度与吸光度符合比尔定律,校准曲线相关系数为0.9999,方法检出限为0.024μg/mL。取不同铜浸出液样品进行精密度考察,硅测定结果的相对标准偏差(RSD,n=12)在0.28%~0.50%之间。将实验方法应用于2个铜浸出液中硅的测定,测得结果与电感耦合等离子体原子发射光谱法(ICP-AES)基本一致。     

电解分离-电感耦合等离子体原子发射光谱法测定砷铜合金中磷

采用电解法分离铜后,电感耦合等离子体原子发射光谱法直接测定了砷铜合金中磷含量。实验结果表明:通过在1.0 mol/L硝酸电解液中加入过氧化氢,能有效抑制砷(在阴极沉积,使铜和磷得到很好分离且电解液中残留的铜含量维持在10.0μg/mL以下,对磷的测定不产生干扰。方法用于砷铜合金样品中磷的测定,回收率在99.5%~103.3%之间,相对标准偏差为0.20%~0.26%(n=11),本法与萃取比色法测定结果相符。     

火焰原子吸收光谱法测定云冈石窟风化岩石中钙铜铁锰

采用HF-HNO3-HClO4混酸消化样品,HNO3溶解盐类,火焰原子吸收光谱法直接测定试液中钙、铜、铁、锰的含量。对共存离子的干扰情况进行了考察,发现大量的Si对测定有干扰,在处理样品时通过生成SiF4除去;磷、铝、钛等元素对钙的化学干扰,通过加入释放剂SrCl2消除。背景吸收使用氘灯扣除。采用标准曲线法测定,Ca、Cu、Fe、Mn的校准曲线的线性范围分别为0.00~20.00μg/mL、0.00~6.00μg/mL、0.00~10.00μg/mL、0.00~6.00μg/mL,检出限分别为0.000 3μg/mL、0.001 3μg/mL、0.002 6μg/mL、0.006 9μg/mL。方法用于云冈石窟风化岩石中钙、铜、铁、锰的测定,相对标准偏差分别为2.8%、3.0%、1.4%、2.9%,加标回收率在96%~110%之间。     

13X分子筛微柱预富集-流动注射火焰原子吸收光谱法测定水中痕量铜

建立了13X分子筛微柱离子交换分离预富集-流动注射火焰原子吸收光谱法检测水中痕量铜的新分析方法。铜以自由离子的形式而非螯合的形式滞留在13X分子筛微柱上,然后用0.5 mL 10%(V/V)HNO3洗脱,通过原子吸收光谱法进行检测。并对流动注射的一些主要参数和各种干扰离子进行了研究。在最优条件下,富集2 min即进样体积为18 mL,测得的线性范围为0.002～0.150μg/mL,检出限为0.5μg/L(3σ,n=11),相对标准偏差(RSD)为1.1%(0.05μg/mL,n=11),富集系数为23.3,采样频率为30次/h。可以通过增加进样体积到36 mL,得到更低的检出限为0.28μg/L。将该方法用于各种水样中铜的分析,加标回收率符合分析要求。     

电感耦合等离子体原子发射光谱测定铜浸出渣中的锡

铜浸出渣含有较高含量的铜,碘量法测定锡时,铜离子干扰滴定结果的判定,影响结果的准确性。为了准确测定铜浸出渣中的锡,试验建立了采用过氧化钠消解铜浸出渣,选择Sn 189.925 nm为分析线,使用电感耦合等离子体原子发射光谱法(ICP-AES)测定铜浸出渣中的锡的方法。试验讨论了过氧化钠的影响,熔样的最佳温度,熔样时间,酸化介质及介质加入量,铜及其它共存元素干扰情况对锡测定结果的影响。结果表明:基体匹配可以消除钠盐背景干扰,最佳熔融温度为700℃;熔样时间为12 min;样品经50 mL热水提取后,加入35 mL盐酸进行酸化处理,铜及其它共存元素对锡测定结果无影响。锡在1～15μg/mL的校正曲线关系良好,相关系数为0.999 998,方法检出限为0.026μg/mL。取不同铜浸出渣样品进行精密度考察,锡测定结果的相对标准偏差(RSD,n=12)在0.38%～1.03%之间,加标回收率在99.42%～100.15%之间。     

电感耦合等离子体原子发射光谱法测定铜阳极泥中钡

铜阳极泥物料成分复杂,钡含量变化较大,现无相关检测标准。实验提出了碱性熔剂熔融-电感耦合等离子体原子发射光谱法(ICP-AES)测定铜阳极泥中钡含量的分析方法。确定的方法如下:准确称取0.2g试样,与4g 碳酸钠-碳酸钾熔剂混合完全,加入0.5mL消电离剂(15g/L氯化铯溶液),在(700±20)℃熔融30min,冷却,浸取,过滤,弃去滤液,将沉淀物溶解,定容。采用Ba 233.527nm作为分析线,建立了电感耦合等离子体原子发射光谱法测定铜阳极泥中钡的方法。通过元素干扰试验,检测10mg钡量,控制相对误差不大于±1%时,下列量(mg)的离子不干扰测定:Pb(II)(400),Cu(II)(350),Sb(V)(50),Bi(III)、Te(VI)(30),Ni(II)(10)。Ba的质量浓度在0.50~25μg/mL范围内与发射强度呈良好的线性关系,相关系数为0.99999;方法检出限为6.0μg/g。将方法用于铜阳极泥实际样品中钡的测定,结果的相对标准偏差(RSD,n=5)小于0.5%,回收率为94%~102%。     

萘相分光光度法测定原油中微量铜

以铬天青S为显色剂,采用萘相分光光度法测定原油中微量铜,并考察了样品灰化和测定条件。在650℃将样品灰化4.5 h以上,用HNO3溶解灰分中的铜,使干扰离子与铜分离。在650 nm波长处的表观摩尔吸光系数ε=7.93×104L.moL-1.cm-1,25 mL溶液中其线性范围为0~8μg。原油测定结果的相对标准偏差为1.90%,回收率为99.83%。     

罗丹明B—铜钨杂多酸—聚乙烯醇体系光度法测定铜

报道一个新的光度法测定铜.在聚乙烯醇存在下铜钨杂多酸络阴离子与罗丹明 B(RB)阳离子形成离子缔合物,在0.96mol/L 硫酸介质中缔合物的最大吸收位于570nm,表观摩尔吸光系数ε=1.53×10~6,铜量在0～0.5μg/25ml 范围内服从比尔定律,测定下限0.36ng/ml(n=12),对0.018μg/ml 铜测定11次的相对标准偏差为0.83%.缔合物至少稳定240h,缔合物的摩尔组成为 Cu:w:RB=1:12:5.考察了40多种共存离子的影响,大多数常见离子不干扰.本法已用于天然水、自来     

阻抑罗丹明6G褪色反应动力学光度法测定痕量钛(Ⅳ)

基于稀H2SO4介质中,痕量钛(Ⅳ)阻抑H2O2氧化罗丹明6G(Rh6G)的褪色反应,建立了测定痕量钛(Ⅳ)的催化动力学光度法。讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响。研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为57.77 kJ/mol。方法检出限为0.45μg/L,线性范围为0~24.0μg/L。在25 mL溶液中,测定0.6μg钛(Ⅳ)的相对标准偏差为2.10%(n=11)。结合溶剂萃取分离,实现了岩石样品中钛(Ⅳ)的测定,结果与认定值相符,相对标准偏差为     

Phaeochromocytoma with myocarditis managed with alpha-methyl-p-tyrosine

A case of bilateral phaeochromocytoma with catecholamine-induced myocarditis is described. The two operations needed allowed comparison of the use of alpha-methyl-p-tyrosine alone and in conjunction with adrenergic blocks in the management of the patient. The combination of both drugs was particularly successful in the relief of symptoms and reduction of catecholamine metabolism as monitored by 4-hydroxy-3-methoxymandelic acid (HMMA) excretion. As myocarditis is a potentially fatal complication, further investigation of the combined use of alpha-methyl-p-tyrosine and adrenergic blocking drugs is suggested in the pre-operative management of patients with phaeochromocytoma.     

Factors related with compliance with tuberculosis chemoprophylaxis

OBJECTIVES: To determine therapeutic tolerance and compliance level with antituberculous chemoprophylaxis. PATIENTS AND METHODS: 587 patients were proposed for antituberculous chemoprophylaxis with isoniazid from January 1995 to June 1996 in Murcia (Spain). RESULTS: 3.6% of the patients gave up treatment because of hepatic intolerance and 73% completed the prophylaxis. Non-compliance related factors were: social risk factors (odds ratio [OR] = 9.31), previous history of allergies (OR = 2.87), previous personal history of tuberculosis-related events (OR = 0.49) and interaction between sex and age. CONCLUSIONS: Support and intervention measures directed to risk groups of a social origin deem to be needed. Control measures and information provided to middle-aged males, with particular emphasis to the first weeks of prophylaxis, should also be implemented.     

Communication with parents of children with cancer

The authors summarize the results of recent work evidencing the existence of latent merozoites during the course of the erythrocytic cycle of the rodent Plasmodia. These merozoites, unlike the majority of merozoites released at schizogony, do not penetrate immediately into the erythrocytes and remain latent for a variable length of time. The merozoites of each of the species or subspecies show marked peculiarities which are responsible for the characteristics of their cycle. The presence of latent merozoites free in the blood, the asynchronous development, and the resistance to chloroquine, are three closely related factors. Knowing that the merozoite is so far drug resistant, and that latent merozoites can maintain the infection for any length of time, it appears important to take into account these purely biological data, when studying the drug resistance of the human falciparum malaria.     

Surgical outcome in patients with epilepsy with occult vascular malformations treated with lesionectomy

PURPOSE: This retrospective study reports the long-term surgical outcome of patients with medically refractory epilepsy and vascular malformations who were treated with lesionectomy. A detailed analysis of surgical failures had been performed in an attempt to define predictors of surgical success and failure. METHODS: Fifteen patients with medically intractable epilepsy and angiographically occult vascular malformations (AOVMs) were treated surgically with lesionectomy at Duke University Medical Center. Lesionectomy consisted of removal of the AOVM and surrounding hemosiderin-stained brain only, without the use of electrocorticography (ECoG) to guide resection. RESULTS: Eleven (73%) patients are seizure free after lesionectomy. Three showed no significant improvement, and one patient died, presumably after a seizure. Age of onset, duration of seizures, age at resection, and gender did not affect outcome. All patients with neocortical AOVMs in whom EEG findings correlated with the site of the lesion were seizure free after lesional resection. Treatment failures were associated with the presence of multiple intracranial lesions, poorly localized or diffuse EEG findings, discordant positron emission tomography (PET) imaging, or with a lesion in close proximity to the limbic system. CONCLUSIONS: Lesionectomy, with removal of surrounding hemosiderin-stained brain, can be considered the procedure of choice in carefully selected patients with epilepsy with occult vascular malformations.