悬浮液进样-AAS法测定TSP中锌、铅和铁的含量

用浓硝酸和高氯酸混酸体系在超声波作用下消解滤膜,加入稳定剂琼脂,用超声波震荡15min制成悬浮液,用火焰原子吸收光谱法测定TSP中的锌、铅和铁的含量,并以传统浓HNO3-H2O2湿法消解-原子吸收光谱法的测定结果为参考对测定值进行t检验,结果表明:RSD≤3.27%(n=6),两种方法的相对误差<±0.85%,且两种方法无显著性差异,说明悬浮液进样法的测定结果准确、可靠。     

Correction model for CO detection in the coal combustion loss process in mines based on GWO-SVM

Accurate detection of CO gas is crucial to the prevention of coal combustion. Tuneable diode laser absorption spectroscopy (TDLAS) is a reliable method for CO detection during coal combustion. The influences of temperature and pressure cause changes in the line strength and linewidth of the index gases’ absorption spectra, leading to sizable measurement errors. To correct the distortion of the CO absorption spectrum caused by temperature and pressure fluctuation, a compensation model based on the grey wolf optimizer–support vector machine (GWO–SVM) was proposed. The results were compared with those of the single SVM, the back propagation neural network (BPNN), and multiple regression analysis (MRA). MRA was revealed to result in the lowest accuracy, which indicated that MRA is not ideal for compensation in TDLAS. The hyperparameter selection of the SVM had the disadvantages of randomness and blindness, which led to instability and large errors. The BPNN achieved better correction in the training stage, but severe overfitting occurred in the testing stage. The modified results revealed that the GWO–SVM model had higher accuracy and stability than the other models. It effectively inhibited the effects of temperature and pressure on the measured concentration and greatly improved the measurement accuracy. The equipment is thus suitable for CO gas detection with the aim to preventing coal combustion loss, and it can be further applied to loss prevention in other process fields.     

基于直接进样-超高效液相色谱串联质谱法的水中2甲4氯残留测定

针对目前水体中MCPA检测灵敏度不够,缺乏一种无需前处理、可直接上机、简单便捷方法的问题,以超高液相色谱串联质谱仪,建立了一种以电喷雾离子源ESI-为电离模式、MRM为监测模式、可直接进样测定水体中MCPA残留的方法。结果表明,最优方法条件为定量离子对199.0/140.9(m/z),流动相乙腈和水梯度洗脱,色谱柱Acquity UPLC HSS T3。在MCPA质量浓度为0.1~100μg/L范围内线性良好(R2=99.99%),检出限为0.006μg/L,定量限为0.018μg/L,是现有直接进样法的23~83倍,完全满足水体中MCPA的检测要求(<0.1μg/L)。在添加水平为1~100μg/L时,回收率为94.30%~105.60%,相对标准偏差为1.05%~3.61%,具有前处理简单、准确性高、精密度好、灵敏度高等优点。     

A simple formula for calculating the ionization potential of two-electron ions

The ionization potential of one-electron ions can be calculated from a well-known simple equation, but no such equation has been available for calculating the ionization potential of multi-electron ions. I report here an equation that accurately gives the ionization potential of helium-like (i.e., two-electron) ions as a function of the atomic number, the relative difference from experimental values being below 1% for all ions for which reliable experimental data were found (Z = 3–29). The equation also predicts the stability of the negative hydrogen ion (the hydride ion), H⁻, although with twice too large a value for the ionization potential.     

Wolfgang Priester: from the big bounce to the $\Lambda$-dominated universe

Wolfgang Priester (1924–2005) was one of Germany’s most versatile and quixotic astrophysicists, reinventing himself successively as a radio astronomer, space physicist and cosmologist, and making a lasting impact on each field. We focus in this personal account on his contributions to cosmology, where he will be most remembered for his association with quasars, his promotion of the idea of a nonsingular “big bounce” at the beginning of the current expansionary phase, and his recognition of the importance of dark energy (Einstein’s cosmological constant Λ) well before this became the standard paradigm in cosmology. In memoriam Wolfgang Priester, 22 April 1924 – 9 July 2005     

紫外荧光法和化学发光法同时测定油品中的痕量硫和氮含量

用紫外荧光法和化学发光法同时测定油品中的痕量硫和氮含量,确定了油品中硫和氮转化为SO2、NO的最佳条件;测定了试样中硫和氮含量,测定结果的相对标准偏差分别为0.92%、3.63%,回收率为92%～104%.     

芦苇和香蒲对重金属钼的吸收特性研究

研究了水生植物芦苇和香蒲对重金属钼的吸收特性.通过短期室内水培实验,对比考察了2种植物对重金属钼的耐毒性、动态去除率、吸收过程及富集情况,并对在不同浓度营养液中植物对重金属钼吸收的影响进行了分析.结果表明,2种植物钼中毒导致其茎叶发黄、蒸腾能力下降,在钼浓度为2～20 mg.L-1时,香蒲对重金属钼的耐毒性较芦苇强.香蒲对重金属钼的去除率高于芦苇,在钼浓度为2 mg.L-1时,香蒲和芦苇去除率分别为87%和62%.2种植物对重金属钼的吸收是一个动态平衡过程,且以被动吸收为主.香蒲对钼的富集量较芦苇高,且植物地上部重金属积累量大于根部,符合超积累植物特征之一.营养液浓度的增加不会提高植物对重金属钼的吸收量,反而会因离子竞争等因素使去除率有所下降.芦苇和香蒲对溶液中钼的吸收均具有显著效果,香蒲吸收效果较芦苇好.     

Biosorption of mercury by Macrocystis pyrifera and Undaria pinnatifida: Influence of zinc, cadmium and nickel

The article investigated the adsorption of Hg(II) on Macrocystis pyrifera and Undaria pinnatifida in monometallic system and in the presence of Zn(II), Cd(II) and Ni(II).     

甲醇衍生法测定环境水体中八种酸性除草剂

文章建立了一种测定环境水体中8种酸性除草剂残留量的分析方法。1 000 mL样品在pH<2的情况下由乙醚分三次萃取后,萃取液经脱水,K-D浓缩至约1 mL,转移到衍生瓶中。在衍生瓶中补加2 mL正己烷、1 mL甲醇、8滴浓硫酸,80℃水浴加热1 h,进行甲醇衍生化处理,衍生后的样品运用气相色谱-质谱联用-分段选择离子扫描技术测定,内标法定量。结果表明:8种除草剂在0.05～2.5μg/L范围内线性均良好;方法灵敏度高,检出限均低于或等于0.02μg/L;方法的准确度和精密度高,在0.10、0.50、1.00、1.50μg/L添加水平下所有除草剂的回收率均在82.07%～116.99%之间,相对标准偏差RSD≤7.68%;经实际样品检测,可用于测定环境水体中酸性类除草剂的残留量。     

流动注射在线富集原子吸收法测定痕量铅镉

在含铅、镉的试液中加入pH=5.72乙酸-乙酸钠缓冲溶液3.20 mL,泵的转速恒为5 mL/min,用自制的强酸性阳离子交换树脂柱对试液中的铅、镉在线富集150 s,1.50 mol/L HNO3溶液洗脱20 s,火焰原子吸收法测定铅、镉的含量。该方法的线性范围分别是0~80.0μg/L、0~40.0μg/L,检出限分别为3.0μg/L、1.0μg/L,富集倍数分别为40倍、35倍。用该方法测定地表水中铅、镉的含量,结果满意。