Simultaneous Determination of Calcium and Magnesium in Water Using Artificial Neural Network Spectro-Photometric Method

A new analytical method using Back-Propagation （BP） artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is established. By condition experiment, the optimum analytical conditions for calcium, magnesium and Arsenazo （Ⅲ） color reactions are obtained. Levenberg- Marquart （L-M） algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2 （nodes）. The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of kt take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%, respectively. The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water, 103.2% and 96.6% in the Yellow River water （Lijin district of Shandong Province）, and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao. It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions. The comparative experiments do not show any obvious differ- ence between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium. This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca^2＋ and Mg^2＋ in tap water and natural water.

Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials——Flame atomic absorption spectrometric method for determination of calcium oxide content

1 Scope This standard specifics the determination of calcium oxide coutent by flame atomic absorption spectrometric method.

Determination of magnesium and aluminum content as principal components in pyrotechnic compositions used for fireworks and firecrackers based on inductively coupled plasma optical emission spectrometric approach （ICP-OES）

Inductively coupled plasma optical emission spectrometric approach（ICP-OES）is used to determine the magnesium and aluminum content as principal components in pyrotechnic compositions used for fireworks and firecrackers. Elements of magnesium and aluminum are commonly found in aluminum powder or magnesium-aluminum alloy powder in pyrotechnic compositions in fireworks and firecrackers. Statistical analysis shows that the magnesium content in pyrotechnics is between 8% to 30% and the aluminum content is between 8% to 35%（roughly）.Concept of this method： suppose the weight of the sample is 400rag,constant volume is IL and the concentlation of magnesium and aluminum is between 12mg/L to 160mg/L in sample solution, the determination scope of the method for magnesium and aluminum content would be between 3% to 40%.Further experiments proved that the fitting correlation coefficient of the magnesium calibration curve is 0.9999 or higher, recovery is 101.01% -101.96%.The fitting correlation coefficient of the aluminum calibration curve is 0.9999 or higher, recovery is 99.36%-103.07%. The allowable differential value is 0.4% between two single tests under repeatable conditions. This method can completely satisfy the requirements of the fireworks and firecrackers industry with high accuracy and good precision.

Novel mechanism for the modification of Al_2O_3-based inclusions in ultra-low carbon Al-killed steel considering the effects of magnesium and calcium

Many researchers have explored the inclusion modification mechanism to improve non-metallic inclusion modifications in steelmaking. In this study, two types of industrial trials on inclusion modifications in liquid steel were conducted using ultra-low-carbon Al-killed steel with different Mg and Ca contents to verify the effects of Ca and Mg contents on the modification mechanism of Al_2O_3-based inclusions during secondary refining. The results showed that Al_2O_3-based inclusions can be modified into liquid calcium aluminate or a multi-component inclusion with the addition of a suitable amount of Ca. In addition, [Mg] in liquid steel can further reduce CaO in liquid calcium aluminate to drive its evolution into CaO–MgO–Al_2O_3 multi-component inclusions. Thermodynamic analysis confirmed that the reaction between [Mg] and CaO in liquid calcium aluminate occurs when the MgO content of liquid calcium aluminate is less than 3 wt% and the temperature is higher than 1843 K.

Chemical Analysis Method for Carbon Bearing Refractory Products——Determination of Magnesium Oxide Content by CyDTA Volumetric Method

This standard specifies the method summary, reagents, apparatus, sampling, procedure, test results calculation and permissible tolerance of the determination of magnesium oxide by CyDTA volumetric method.

The role of Ca,Al and Zn on room temperature ductility and grain boundary cohesion of magnesium

It is know from literature that small additions(<1 wt%)of Ca,Al and Zn significantly improve the intrinsic ductility of Mg.The exact role of each element,both qualitatively and quantitatively,and their combined effects,however,are poorly understood.Here we achieved a much clearer view on the quantitative role of each element with respect to ductility improvement and on the collaborative effect,particularly of Ca and Zn in Mg.Some of our findings and conclusions are in disagreement with data and interpretation found in literature.Four different alloys,namely,Mg-0.1 Ca,Mg-0.1 Ca-1 Al,Mg-0.05 Ca-1 Al,Mg-0.1 Ca-2 Al-1 Zn(all are in wt%)were selected for this investigation.All alloys were treated such that approx.similar grain sizes and textures were obtained.This largely excludes the effect of extrinsic factors on ductility.EBSD-guided slip trace analyses reveal that the addition of Ca eases activation of prismatic and pyramidal II slip systems.Using in-situ deformation experiments in SEM and atom probe tomography observations of grain boundaries direct evidence is given for the individual and synergetic effects of Ca and Zn on grain boundary cohesion as an important contribution to improve the ductility of these alloys.We conclude that Ca reduces the slip anisotropy and ameliorates ductility,however,the weak grain boundary cohesion in the Mg-0.1 wt%Ca alloy limits the material’s tensile ductility.The addition of Zn alters the Ca segregation at the grain boundaries and helps to retain their cohesive strength,an effect which thus enables higher ductility and strength.The further addition of Al primarily improves the strength.The results show that the balanced influence of reduced slip anisotropy on the one hand and increased grain boundary cohesion on the other hand allow to design a high strength high ductility rare-earth free Mg alloy.

阿托伐他汀钙体外质量一致性评价及含量快速测定

建立超高效液相色谱法(UPLC)快速测定阿托伐他汀钙的含量测定方法,并对市售药品进行分析评价。用Waters Acquity BEH C18(2.1 mm×100 mm, 1.7μm);以乙腈-20 mmol·L^(-1)醋酸铵溶液52∶48为流动相;检测波长为238 nm;流速为每分钟0.35 mL;进样体积2μL。阿托伐他汀钙和阿托伐他汀钙杂质D的线性关系、精密度、稳定性、重复性良好;加样回收率分别为100.50%和105.09%,RSD分别为2.20%和1.70%(n=6)。本方法检测时间短、准确度高、操作简单、重复性好,可为阿托伐他汀钙片的质量评价提供理论依据。

UPLC法快速测定苯磺酸氨氯地平、格列美脲和阿托伐他汀钙中的含量

建立超高效液相色谱法(UPLC)快速测定三高药物苯磺酸氨氯地平、格列美脲和阿托伐他汀钙的含量测定方法。用Waters Acquity BEH C_(18)(2.1 mm×100 mm,1.7μm),以乙腈-20 mmol·L^(-1)醋酸铵溶液52∶48为流动相;检测波长为238 nm;流速为0.32 mL·min^(-1)。苯磺酸氨氯地平、阿托伐他汀钙和格列美脲的线性关系、精密度、稳定性、重复性良好;加样回收率的平均值分别为101.20%、99.79%、100.26%,RSD分别为1.69%、1.07%、1.85%(n=6)。本方法准确度高、操作简单、出峰时间短,可为三者的质量评价提供理论依据。

高效液相色谱法同时测定口服五维赖氨酸葡萄糖中6种成分含量

目的建立同时测定口服五维赖氨酸葡萄糖中6种成分含量的高效液相色谱法。方法色谱柱为Alltima C_(18)柱(250 mm×4.6 mm,5μm),流动相为5 mmol/L庚烷磺酸钠溶液(用20%磷酸水溶液调pH至2.5)-乙腈(梯度洗脱),流速为1.0 mL/min,检测波长为200 nm(泛酸钙、盐酸赖氨酸),261 nm(烟酰胺、维生素B2、维生素B1),290 nm(维生素B6),柱温为40℃,进样量为20μL。结果泛酸钙、烟酰胺、维生素B6、盐酸赖氨酸、维生素B2、维生素B1质量浓度分别在1.174~23.49μg/mL、4.220~84.40μg/mL、0.5207~10.41μg/mL、20.88~417.7μg/mL、0.4278~8.555μg/mL、1.676~33.52μg/mL范围内与峰面积线性关系良好(r=0.9999);精密度、稳定性、重复性试验结果的RSD均小于2.0%;平均加样回收率分别为101.02%,99.78%,100.30%,100.32%,95.61%,99.26%,RSD分别为0.99%,0.60%,0.57%,1.85%,1.69%,0.71%(n=6)。结论该方法简便,结果准确可靠,可用于同时测定口服五维赖氨酸葡萄糖中6种成分的含量。

核磁共振磷谱法测定磷酸氢钙咀嚼片中药物含量

目的建立一种高精密度和高专属性的核磁共振磷谱定量方法(31P-qNMR),用于检测磷酸氢钙咀嚼片中含磷药物的含量。方法使用六甲基磷酸酰胺作为内标,采集磷酸氢钙咀嚼片剂溶液的磷谱数据。研究磷酸氢钙在浓度范围1.0~9.0 mg/ml内的线性关系,并进行加样回收率和重复性实验。结果磷酸氢钙与内标的峰面积比在1.0~9.0 mg/ml范围内显示出良好的线性关系,回归方程为A=0.0043+0.1836C。低、中、高3种浓度的加样回收率分别为98.0%、98.1%、98.4%,相对标准偏差(RSD)分别为0.31%、0.68%、0.62%(n=9)。测定得到的磷酸氢钙咀嚼片中磷酸氢钙的平均含量为98.1%。结论成功建立了一种精密度高且专属性强的磷酸氢钙咀嚼片含量检测方法。该方法无需自身对照物,前处理过程简便,检测速度快,为含磷药品质量控制提供了新的技术支撑。

电感耦合等离子体发射光谱法快速测定白云石、石灰石中高含量氧化钙

建立电感耦合等离子体发射光谱法测定白云石、石灰石中高含量氧化钙。样品经10 mL盐酸溶液(1∶1)、1.5 mL浓硝酸溶解后,设定测试功率为1 150 W,分析谱线波长为373.6 nm,氩气流量为0.7 L/min,辅助气流量为0.5L/min,氩气压力为0.2 MPa,观测高度为13 mm,泵转速为50 r/min,采用等离子体原子发射光谱法进行测定。钙的质量浓度在0~10.0μg/L范围内与信号强度线性良好,相关系数为0.999 9,方法检出限为3.2μg/L。采用所建方法分别测定白云石和石灰石标准样品,测定结果的相对标准偏差分别为0.28%~0.31%、0.19%~0.25%(n=6),测定平均值与标准值的相对误差分别为0.20%~0.48%、0.18%~0.22%。分别用所建方法与GB/T 3286.1—2012方法测定白云石、石灰石样品,测定结果的相对误差分别为0.26%~0.29%、0.34%~0.48%。该方法满足白云石、石灰石中高含量氧化钙的测定要求。

碳酸钙D_(3)颗粒(Ⅱ)中维生素D_(3)含量测定的不确定度评定

目的建立测定碳酸钙D_(3)颗粒(Ⅱ)中维生素D_(3)含量不确定度的评定方法。方法采用《国家药品标准》WS1-XG-033-2021中维生素D_(3)含量测定方法进行测定,同时依据《测量不确定度评定与表示》JJF 1059.1-2012中的相关规定,建立测定维生素D_(3)的不确定度数学模型,并对不确定度来源进行分析和评定。结果维生素D_(3)含量的不确定度来源主要有对照品纯度(PR),对照品称量(MR),对照品溶液制备(VR),对照品溶液测定(AR),样品称量(MS),供试品溶液制备(VS),样品平均装量(W),样品溶液测定(AS),高效液相色谱仪(I)及方法偏倚(B)。高效液相色谱外标法测定碳酸钙D_(3)颗粒(Ⅱ)中维生素D_(3)含量的合成不确定度为0.0228,扩展不确定度为3.22%(k=2,置信概率为95%)。方法偏倚引入的相对标准不确定度为1.83×10^(-2),为潜在风险点。结论所建立的方法适用于高效液相色谱外标法测定碳酸钙D_(3)颗粒(Ⅱ)中维生素D_(3)含量测定的不确定度评定,但测定方法回收率较低。建议对该方法进行影响因素试验考察,以改进检验方法,提高平均回收率。

高效液相色谱法测定碘佛醇注射液中乙二胺四醋酸二钠钙的含量

目的建立碘佛醇注射液中乙二胺四醋酸二钠钙含量的测定方法。方法采用高效液相色谱法测定碘佛醇注射液中乙二胺四醋酸二钠钙的含量,色谱柱为phenomenex GeminiNX-C18110Å(4.6 mm×25 cm,5μm);等度洗脱;流动相为0.4%四丁基氢氧化铵(用磷酸调节pH至6.50)-乙腈(3∶1);检测波长:260 nm;流速:1 ml·min^(-1);柱温:40℃,进样体积:20μl。结果乙二胺四醋酸二钠钙在0.32~23.63μg·ml^(-1)浓度范围内与峰面积线性关系良好(相关系数1.0000),平均回收率为99.12%,RSD为0.34%(n=6)。结论本方法简便,易于操作,准确性和重复性良好,可用于碘佛醇注射液中乙二胺四醋酸二钠钙的含量测定。

在线分析仪在盐水系统中的应用

介绍了盐水系统2035系列在线分析仪的原理、分析步骤以及优化改进措施,并论证了仪器的可靠性。

采用综合评价模型优化樱桃番茄的灌溉与钙镁肥组合

【目的】钙、镁肥效果既互相影响又受灌溉量影响。尝试用综合评价模型优化包括钙、镁和水等多因子的配施方案,为樱桃番茄高效生产提供指导。【方法】水、氮、钾、钙、镁五元二次正交旋转组合设计(1/2实施)微区试验在陕西杨凌大棚内进行,供试樱桃番茄品种为‘粉妹1号’,共36个处理。测定樱桃番茄生长、产量、品质、水肥利用率等共21个指标。采用Pearson相关性分析、组合评价方法对指标进行分级、综合评价,构建樱桃番茄综合评分对5个因子水平的响应模型。【结果】构建了包含14个指标的樱桃番茄综合评价体系;组合赋权确定了各指标最终权重,其中产量权重(0.2324)最大,净光合速率权重(0.0183)最小,这表明产量是对试验因子变化最敏感的指标。通过整体差异综合评价,发现樱桃番茄的综合评分随灌水量和氮肥水平的增加呈先增加后降低的趋势,灌水量0水平与–2和+2水平处理之间的差异显著大于氮肥水平之间的差异,随钙肥水平的增加略呈先增加后降低的趋势,而随钾和镁肥水平的增加几乎无显著变化。采用降维分析,当水、氮和钾处于0水平(适当水平)时,樱桃番茄的综合评分以钙和镁为0水平附近时最高;考虑5个因子的交互作用,基于整体差异组合的综合评分最优区间为:灌水量56.26~59.03 L/株、N 6.05~7.03 g/株、K2O 5.97~6.50 g/株、CaO 2.92~3.30 g/株、MgO 0.58~0.64 g/株。【结论】采用综合评价模型可以兼顾生长、产量、品质和资源利用率,提出最优的水肥组合方案。本试验提出的樱桃番茄适宜施肥区间验证了该方法的可行性。

离子色谱法测定异甘草酸镁注射液中镁离子和钠离子的含量

目的建立用离子色谱法同时测定异甘草酸镁注射液中镁离子和钠离子含量的方法。方法用阳离子交换离子色谱法,色谱柱为Dionex IonPac^(TM)CS12A RFIC^(TM)分析柱(250 mm×4 mm,8μm)和CG12A保护柱(50 mm×4 mm),淋洗液为20 mmol·L^(-1)的甲烷磺酸溶液,流速为1.0 mL·min^(-1),抑制器为Dionex CERS 500(4 mm),抑制电流为59 mA,电导检测器,柱温为30℃,进样体积为25μL。结果镁离子、钠离子质量浓度分别在0.5~10、10~100μg·mL^(-1)的范围内与其峰面积线性关系良好,相关系数分别为0.9999、0.9998;平均加样回收率分别为100.29%、101.39%(n=9),RSD值均为1.09%(n=9);精密度、重复性、稳定性实验的RSD值均小于2%(n=6)。结论所建立的离子色谱法可同时测定异甘草酸镁注射液中镁离子和钠离子的含量。

钙镁水滑石对双季稻产量及稻米镉积累的影响

为研究不同用量钙镁水滑石对镉污染稻田土壤特性、双季稻产量与稻米镉积累的影响,探讨镉污染双季稻田钙镁水滑石的最佳施用方式。2021年,以早稻品种“湘早籼45号”和“陆两优996”,晚稻品种“创两优669”和“玉针香”为试验材料,在湖南省郴州市良田镇重度镉污染稻田(全镉含量1.16 mg/kg)开展大田试验,比较研究钙镁水滑石(0,CK;早稻基施3000 kg/hm^(2),T1;早稻基施1500 kg/hm^(2),T2;早稻基施750 kg/hm^(2)+晚稻基施750 kg/hm^(2),T3)4个处理下土壤特性、双季稻产量构成与植株镉积累情况。结果表明:(1)钙镁水滑石可提高土壤pH与碱解氮、速效钾、速效磷含量,早稻成熟期分别提高0~3.06%,4.30%~13.80%,6.67%~40.00%,25.53%~30.47%;晚稻成熟期分别提高1.56%~4.07%,11.79%~14.50%,15.79%~31.58%,3.73%~17.17%;增幅表现为T1>T2>T3。(2)施用钙镁水滑石可降低土壤有效镉含量,早、晚稻成熟期各降低5.26%~42.86%,18.19%~36.84%;降幅表现为T1>T2>T3。(3)糙米镉含量和成熟期植株地上部镉积累量以T1最低,T2、T3次之,CK最高,“湘早籼45号”分别降低33.33%~44.44%,4.89%~20.76%;“陆两优996”分别降低30.00%~60.00%,6.00%~30.98%;“玉针香”分别降低27.78%~50.00%,15.93%~34.07%;“创两优669”分别降低26.67%~60.00%,12.58%~28.56%。(4)钙镁水滑石使早、晚稻产量分别提高4.11%~10.79%,1.69%~11.29%。“湘早籼45号”、“创两优669”和“玉针香”产量以T1处理最高,陆两优996产量以T2处理最高,除玉针香外,各品种T1和T2处理产量差异不显著。可见,较大的钙镁水滑石施用量对水稻的增产、降镉效果较好,但综合考虑处理间水稻产量与镉含量差异的显著性及钙镁水滑石成本,以钙镁水滑石1500 kg/hm^(2)较为适宜。

数据评价在鸡蛋壳钙镁含量测定实验中的应用

数据评价是定量分析的重要内容。以蛋壳中钙镁含量的测定实验为例,对同种方法同一样品单次测量的数据和同一样品用不同方法测量的数据进行了评价。样品分别采用酸碱滴定法和配位滴定法测定,在用G检验法剔除单次测量可疑数据之后,样品的钙镁总含量分别为83.22%和92.57%(以CaCO_(3)的质量分数表示)。然后通过F-t联合检验法得出两种滴定方法所得结果存在显著性差异。通过该实验,学生加深了对数据处理在实际体系中运用的理解。

EDTA滴定法测定芎芷石膏汤中钙离子含量

目的建立乙二胺四乙酸二钠(EDTA)络合滴定法测定芎芷石膏汤中钙离子含量。方法芎芷石膏汤样品经无水乙醇脱色处理后,单因素结合正交试验对影响钙离子滴定反应的钙离子浓度、滴定pH值、稀盐酸加入量、指示剂加入量、掩蔽剂5个因素进行考察。以钙标准溶液EDTA用量对其浓度作线性回归,并对测定方法进行精密度、稳定性、重复性、加样回收率试验。在优化条件下测定3批芎芷石膏汤样品中钙离子含量。结果确定最佳测定条件为取样0.1 g,滴定pH值为13,稀盐酸加入量为2.0 ml,指示剂加入量为0.15 g,不加掩蔽剂。该测定方法下,钙离子浓度在0.60~2.98 mmol/L范围内呈现良好的线性关系,回归方程为y=10.05x-0.0498,r=0.9999。精密度、稳定性、重复性试验均RSD<3%,平均加样回收率为100.54%,RSD为0.72%(n=6)。以上均符合定量分析要求。3批芎芷石膏汤样品中钙离子含量分别为40.29,41.22,39.90 mg/g。结论优选的EDTA络合滴定法操作简便、准确可靠,可用于芎芷石膏汤中钙离子含量的测定。

EDTA滴定法测定硅钙合金中钙含量的不确定度评定

介绍了EDTA滴定法测定硅钙合金中钙含量的操作过程,分析了测定过程中不确定度的主要来源,对各不确定度分量进行了量化计算,得出合成标准不确定度、扩展不确定度及测定结果的置信区间.数据表明,EDTA滴定法测定硅钙合金中钙含量不确定度主要因素是EDTA标准滴定溶液的浓度、EDTA标准滴定溶液的用量、试液重复性测量以及量取试液的体积.当钙质量分数为31.20%时,其标准扩展不确定度为0.31%(k=2).