差示光度法测定硅钙中的硅

硅钙中硅的分析一般使用差减法,但该法测定的硅值往往比实际值高出2—4％。为了保证出厂结果真实,用差示光度法分析硅时,遇到一个很大的困难,即在常温条件下用硝氟酸溶解硅钙比硅铁和硅铬还困难。因此采取了两条措施:(1)制样的粒度必须在160目以上;(2)必须用相同粒度的硅钙标     

火焰原子吸收光谱法测定硅钙合金中硅

提出用N2O-C2H2火焰原子吸收光谱法测定硅钙合金中硅。在优化的实验条件下,硅质量浓度在0~50μg/mL范围内呈良好的线性关系,检出限为0.05μg/mL。方法达到了仪器分析的质量控制要求,具有良好的灵敏度,干扰少,重复性好。用于硅钙合金中硅的控制分析,相对标准偏差小于1.0%,结果与认定值相符。     

硅钙合金、硅钡合金中铝量的测定

本文介绍了一种硅钙合金、硅钡合金中铝量的测定方法。样品用硝酸溶解，氢氟酸挥硅，高氯酸冒烟，加入氯化钡溶液保持电解质平衡，用硼酸溶液去氟，强碱分离铁、锰、钒、铌等干扰元素，用过量的EDTA络合铝，通过调节酸度，用PAN作指示剂，用硫酸铜标准溶液返滴定来测定硅钙合金、硅钡合金中铝量。     

硅钙合金中含钙量变化规律的研究

一、前言硅钙合金的生产方法有二种:电热法和电硅热法。用电硅热法生产硅钙合金能耗低,且合金的有害杂质含量低。若将此法生产的硅钙合金折算成硅钙31牌号时,其夹杂含量是:S0.016％、P0.016％。而电热法生产的硅钙31的夹杂含量是:S0.08％、     

12.5MVA电炉硅钡与硅钙钡合金试验

介绍了12．5MVA硅铁电炉转炼硅钡和硅钙钡的试验情况，论述了硅钡、硅钙钡的炼原理和对试验中有关问题的看法。     

硅钙铁的试制和试用

本文对硅钙铁的试制和试用进行了工业规模初步研究,讨论了用电硅热法生产硅钙铁合金的原料、配料、操作、工艺中的一系列问题。试制出的含钙15—19％的硅钙铁用于炼钢连铸钢水脱氧合金化中,可等量代替国标Ca28Si60牌号的硅钙合金。提出了使用硅钙铁炼制某些钢种在经济上和技术上的可行性。     

矿热炉冶炼硅钙钡铝合金

硅钙钡铝合金为钡系合金中高级复合合金,是含钡合金中强脱氧,脱硫剂。它是特殊钢常用的终脱氧剂,使钢中的氧达到最低(4.3ppm);同时形成含钙、钡、铝等复杂夹杂物易从钢中上浮,纯洁钢液,提高钢的内在质量。目前生产方法有:(1)硅铝合金冶炼加入石灰、钡矿而成硅钙钡铝合金;(2)分层法冶炼硅钙钡合金加入铝土矿而成     

矿热炉冶炼高品位硅钙钡合金

在硅钙合金分层法冶炼基础上,加入钡矿用硅热法还原钡元素,制得高品位硅钙钡合金。冶炼中正确控制(CaO+BaO)/SiO_2、CaO/BaO 的比值等影响因素,可使冶炼操作顺行。硅钙钡合金在管20、管20g、18MnHP 钢中应用,脱氧率比用 Si_(20)Al)(50)合金提高30—40%,脱硫效率提高15—20%,夹杂物得到变性处理,其总量降低30—40%。     

硅钙钡及硅钡铁合金中钙、钡的测定

硅钙钡及硅钡铁合金中钙、钡的测定刘道平，陈先聪，周斌，汪绍红（重庆钢铁专科学校，重庆，６３００５０）硅钙钡及硅钡铁合金是炼钢中很好的脱氧剂，并且有很好的脱硫、磷能力，对冶炼含磷较低的不锈钢起重要作用。除此，还能改变钢中非金属夹杂物的物性，可球化或细化...     

X射线荧光光谱法分析硅钙复合脱氧剂中的硅、钙含量

采用X射线荧光光谱仪分析硅钙复合脱氧剂的硅、钙,以高炉渣、硅石、石灰石标样混合制备的标准样品作为校准样品,进行工作曲线的绘制,曲线适应硅钙复合脱氧剂的硅、钙的含量范围。灼烧后的样品用四硼酸锂做熔剂,高温熔融制样,消除粒度效应。将该方法与化学法进行对照,硅、钙的分析结果准确度能够满足要求,且快速、简便。     

高频燃烧红外吸收法测定石灰石和白云石中硫

采用GB/T 3286.7—2014中的两种方法分别对石灰石和白云石中硫进行测定,样品不经过预灼烧直接用高频燃烧红外吸收法测定(简称直接法)所得结果会明显低于其经预灼烧法处理后再测定(简称预灼烧法)的结果。考虑到预灼烧法操作较为繁琐,实验对直接法测定结果偏低的原因进行分析,并对直接法的助熔剂条件进行了改进,建立了不用对样品进行处理,直接用高频燃烧红外吸收法测定石灰石和白云石中硫的方法。收集直接法和预灼烧法对白云石标准样品测定时产生的粉尘,采用X射线荧光光谱法(XRF)对其成分进行半定量测定,同时采用高频燃烧红外吸收法对其中硫再次测定。结果表明,直接法所得粉尘中氧化钙的质量分数约为7%、氧化镁的质量分数约为4%,而预灼烧法的粉尘中氧化钙和氧化镁的质量分数均小于0.1%;直接法所得粉尘中硫的质量分数为0.012%,预灼烧法所得粉尘中硫的质量分数仅为0.002%。这说明直接法测定时硫释放率偏低的主要原因可能与样品中高含量的碳酸钙、碳酸镁相关,推测认为:直接法测定时产生的二氧化碳气流将碳酸钙、碳酸镁分解生成的部分碱性氧化物氧化钙、氧化镁细粉带入仪器的低温气路区,造成氧化钙或氧化镁与二氧化硫酸性气体重新反应,最终导致直接法测定硫的结果偏低。实验在国家标准方法(GB/T 3286.7—2014)的助熔剂条件基础上,加入三氧化钼粉酸性氧化物以有效避免样品中的高含量碳酸钙、碳酸镁对测定的影响。改进后的测定条件为:称取0.20 g样品与0.5 g三氧化钼粉在坩埚中混合,再加入0.3 g锡粒、0.5 g纯铁和1.5 g钨粒。实验方法应用于石灰石和白云石实际样品中0.01%～0.27%(质量分数)硫的测定,分析结果与重量法或燃烧-碘酸钾滴定法一致,相对标准偏差(RSD,n=8)为0.8%～2.6%。     

粗金粉中金和银的联合测定

运用传统的火试金法处理粗金粉样品,建立了重量法测定粗金粉中金量、火焰原子吸收光谱法测定银量的新方法。采用留铅灰吹的方法使样品中的金银富集在1~2 g的铅合粒中,用HNO₃溶解铅合粒,然后采用重量法测定金量,火焰原子吸收光谱法于波长328.1 nm测定银量。本方法有效地解决了粗金粉中金银不能联合测定的难题,银的方法检出限为0.003 1 μg/mL。将该法用于实际样品分析,测定结果与国标法测定结果一致,金的相对标准偏差≤0.07 %,银的相对标准偏差≤1.2 %,且金和银的银回收率分别为100 %和98 %~101 %之间。     

偏最小二乘-神经网络光度法同时测定钢中钨和钼

在钨(钼)-2,4 二氯苯基荧光酮-CTMAB显色体系中,用偏最小二乘法(PLS)与神经网络(NN)联用辅助分光光度法,不经分离,同时测定合金钢中钨和钼。经比较,结果优于PLS法和BP神经网络法。     

电感耦合等离子体原子发射光谱法测定非晶合金中高含量硼

采用电感耦合等离子体原子发射光谱法(ICP-AES)代替传统的化学分析方法,建立了快速测定非晶合金中的高含量硼的方法。对样品的处理方法和测试条件进行研究。结果表明:试样用王水溶解后,加入氢氟酸,继续在90℃水浴中加热溶解试样,试样溶解完全,实现了对难溶合金中B元素的快速测定。在选择硼的分析线为182.640 nm下测定,共存元素没有干扰,基体铁和钴的干扰采用基体匹配方法消除。通过回收试验及精密度试验,证明方法有较高准确度和精密度,分析周期比化学法短。     

氯金酸钠代替氯金酸测定矿石中金含量的研究

矿石中金含量的测定通常采用王水溶解,使其形成氯金酸后再用原子吸收法或容量法进行测定,但是氯金酸溶液稳定性容易受温度、酸度、浓度、外界条件和容器吸附等因素的影响。为了提高氯金酸溶液的稳定性可用碱金属使其生成相对稳定的氯金盐,但未真正实践应用。本文提出了一种以氯金酸钠代替氯金酸做标准溶液测定矿石中金含量的方法,应用本方法配制的标准溶液放置3～4个月未出现还原偏低现象。该方法采用活性炭吸附柱富集金,用王水溶解,再加入饱和氯化钠溶液制得氯金酸钠溶液。采用原子吸收法,在日立Z-2000原子吸收分光光度计上测定金的含量。实验结果表明：该测定方法可靠,误差较小,稳定性好;测定的绝对灵敏度可达0.025 μg/g,测定范围为0.04～1 000 μg/g,适合用于大批量地质矿石样品中金的测定。     

Improved the accuracy of 99mTc-MAG3 plasma clearance method: the problem of the calculated plasma volume and its modification

The 99mTc-MAG3 plasma clearance method (MPC method), reported by Oriuchi et al., is a simple and useful count-based gamma camera method for calculating the 99mTc-MAG3 plasma clearance (CLMAG). However, a discrepancy of CLMAG calculated by MPC method (MPC-CLMAG) from the tubular extraction rate (TER) calculated by Russell's single-sample clearance determination (Russell-TER) was noted. The calculated plasma volume is assumed to be the cause. Since the plasma volume is reported to have a linear correlation with body surface area, Dissmann's formula was applied to calculate the plasma volume. Then Dissmann's formula was replaced by Ogawa's formula in the MPC method, and the procedure was then called the modified MPC method. The CLMAG were obtained using MPC method, modified MPC method and the TER was obtained Russell's method in 95 patients with urological disorders. Then the MPC-CLMAG and modified MPC-CLMAG were compared with Russell-TER. Comparison of the MPC-CLMAG with the Russell-TER demonstrated a coefficient of correlation of 0.82, but dissociation of the slope of regression lines was found between males and females. The modified MPC-CLMAG improved the coefficient of correlation to 0.92, and diminished the dissociation of the slope of regression lines between males and females. We verified that the dissociation was due to the plasma volume calculated by Ogawa's formula. Ogawa's formula included hematocrit, body weight, body height and different coefficients for gender. The plasma volume calculated by Ogawa's formula were lower in males and higher in females than that calculated by Dissmann's formula. And marked discrepancy in the plasma volume in patients with a body surface area below 0.5 m2 was observed. So the MPC method might become more accurate by substituting Dissmann's formula for Ogawa's formula resolting in a method that is applicable to both males and females, children and adults in clinical use.     

空气-乙炔火焰原子吸收光谱法测定钐钴永磁合金中钙量

采用王水分解样品,在3%(V/V)的盐酸介质中,以标准加入法绘制校准曲线,建立了空气-乙炔火焰原子吸收光谱法(FAAS)测定钐钴永磁合金中钙的方法。分别在钐、钴单独存在以及共同存在的条件下考察了其对测定的影响,结果表明,若采用火焰原子吸收光谱法测定钐钴永磁合金中钙,钐钴基体对测定的基体效应不可忽略且情况复杂。因此,实验选择标准加入法来校正钐钴基体效应对测定的影响。方法检出限为13μg/g,方法测定下限为44μg/g。干扰试验表明,以标准加入法的校正模式进行钐钴永磁合金中钙量的测定,样品中共存元素铜、铁、锆对测定的干扰可忽略。方法应用于钐钴永磁合金中实际样品中质量分数为0.0065%钙的测定,测定值与国家标准方法GB/T 12690.15—2006(电感耦合等离子体原子发射光谱法)相符,测定结果的相对标准偏差(RSD,n=11)小于14%。方法可用于钐钴永磁合金样品中0.0050%~0.50%(质量分数)钙量的分析检测。     

Comparison between cell motion analyser, autosperm, and conventional semen analysis

With the aim of explaining some of the controversy on the value of computer-assisted methods of semen analysis, a study was conducted comparing the fully automated cell motion analyzer (CMA), the semi-computerized autosperm system (AS) and the conventional manual method. The CMA equipment gave higher values for sperm concentration than the mean of the three methods. Sperm concentration estimated with the conventional method was below the average of the three methods. The conventional method overestimated sperm motility, which was underestimated by CMA. The correlation between sperm velocity characteristics estimated by CMA and AS was significant, but only 18% of variability of one method could be explained by variability of the other. The reasons for the discrepancy between velocity measurements in the two methods are discussed in relation to possible shortcomings in sperm paths smoothing using the CMA method and the effect of technician training in the AS method. The AS method was found to provide more reproducible results which correlated better with those of the manual method as recommended by the World Health Organization.     

Comparison of three methods for determining aflatoxins in melon seeds

The suitability of 3 methods for determining aflatoxins in melon seeds was examined. The first 2 are the Contaminants Branch (CB) method and the Best Foods (BF) method, both official methods for determining aflatoxins in peanuts and peanut products. The third method, the modified CB method-Rapid Modification of the Cottonseed (CB-RCS-Mod) method, devised in this work, was derived by combining steps from the CB method and the Rapid Modification of the Cottonseed method. The CB method was superior to the other 2 methods for quantitation of aflatoxins. It gave better recoveries and cleaner extracts that exhibit less fluorescent interference for thin-layer chromatography (TLC) than the BF method. Also, its solvent efficiency was better than that of the CB-RCS-Mod method. With the CB method, recoveries from spiked samples were 85.0% for aflatoxin B1 and 90.0% for aflatoxin B2. Recoveries of G aflatoxins were more variable, averaging 90.0% for aflatoxin G1 and 72.5% for aflatoxin G2. Total aflatoxin recovery was 86.5% for the CB method. At a low aflatoxin contamination level (8 micrograms B1/kg sample), aflatoxin B1 was detectable by the CB method but not by the BF method. Detection of aflatoxins in BF method sample extracts by TLC was not improved by the use of chloroform-acetone-water (88 + 12 + 1), benzene-ethanol-water, or ether-methanol-water (96 + 3 + 1) in place of the standard chloroform-acetone (88 + 12) developer. Use of ether-methanol-water (96 + 3 + 1) for detecting aflatoxins by TLC in the CB method extracts increased interference compared with the standard chloroform-acetone (88 + 12) developer.     

煤气中粗苯含量的气相色谱分析方法研究

建立了一种新的测定煤气中粗苯的方法,用注射器直接取煤气样,用无水乙醇作吸收剂,用保留时间定性,用外标法乘以经验系数定量.与传统的活性碳吸附水蒸汽蒸出法相比,分析时间由5～6 h缩短到15～20min,具有进样量少、操作简便、结果准确等优点.