电热鼓风干燥箱解脱–火焰原子吸收光谱法测定地质样品中金的含量

建立高海拔地区电热鼓风干燥箱解脱–火焰原子吸收光谱法测定地质样品中的金的方法。高海拔地区由于大气压低,水的沸点低,使得泡塑吸附金的解脱率不高。为了得到准确的分析结果,采用电热鼓风干燥箱代替水浴锅来解脱泡塑吸附金,优化后的解脱条件:解脱温度为105℃,解脱时间为30 min,在此条件下金的解脱率为91.19%。金的质量浓度在0.00~10.00μg/mL范围内与其吸光度呈良好的线性关系,相关系数r=0.999 6,方法检出限为0.012μg/mL。测定结果的相对标准偏差为2.15%(n=7),加标回收率为96.0%~102.5%。用该方法测定国家一级标准物质,测定结果与参考值相符。该方法准确、可靠,适用于高海拔地区地质样品中金的测定。     

阴离子交换树脂分离同位素稀释等离子体质谱法快速测定地质样品中的铼

建立了适合大批量低含量Re地质样品的测定方法,0.2 g样品通过HF,HNO3分解后在2 mol/L的HCl介质中用阴离子交换树脂进行振荡吸附,然后用HNO3(1+1)解脱,同位素稀释等离子体质谱法测定。     

预还原氢化物发生-原子荧光光谱法快速测定化探样品中的As、Sb、Bi、Hg

通过对化探样品进行王水密闭溶解,饱和的硫脲-抗坏血酸预还原,运用氢化物发生-原子荧光光谱法实现了地质样品中As、Sb、Bi、Hg元素的任意配对以及连续快速测定。实验确定了原子化器高度为14mm,最佳溶样时间为1h。在优化条件下,结果显示还原剂(硫脲-抗坏血酸)对Hg、Bi测定结果无影响,且Hg、Bi测定结果在预还原20min至48h内都很稳定,测定结果良好,Cu、Co、Ni、Au、Ag、Cd、As、Sb、Bi、Se、Ge等金属离子对预还原测定汞均无干扰,对比实验表明还原剂体系下汞荧光强度值基本不变。方法的检出限低、精密度好、准确度高、操作简便,有效避免了元素污染问题,可满足大批量地质样品分析测定的需要。     

预还原氢化物发生—原子荧光光谱法快速测定化探样品中的As,Sb,Bi,Hg

通过对化探样品进行王水密闭溶解,饱和的硫脲-抗坏血酸预还原,运用氢化物发生-原子荧光光谱法实现了地质样品中As、Sb、Bi、Hg元素的任意配对以及连续快速测定。实验确定了原子化器高度为14mm,最佳溶样时间为1h。在优化条件下,结果显示还原剂(硫脲-抗坏血酸)对Hg、Bi测定结果无影响,且Hg、Bi测定结果在预还原20min至48h内都很稳定,测定结果良好,Cu、Co、Ni、Au、Ag、Cd、As、Sb、Bi、Se、Ge等金属离子对预还原测定汞均无干扰,对比实验表明还原剂体系下汞荧光强度值基本不变。方法的检出限低、精密度好、准确度高、操作简便,有效避免了元素污染问题,可满足大批量地质样品分析测定的需要。     

地球化学样品中铷元素的方法选择研究

本文针易电离元素铷,采用原子吸收光谱法和电感耦合等离子体多元素测定的两种方法进行了探讨。三酸溶样的原子吸收法需要加入硫酸钾做电离抑制剂,操作繁杂但检出限更低,线性范围窄;四酸溶样的等离子体光谱法方法简便快速,适合大批量多元素快速测定。两种方法结合使用可实现大批量样品中铷的快捷、简单、准确检测。     

快速加热容量法测定土壤中有机质含量

建立快速容量法测定土壤中有机质的分析方法。采用恒温电热板控温加热替代油浴加热溶解样品,使用硫酸银作为催化剂,重铬酸钾–硫酸标准溶液作为氧化剂,使用硫酸亚铁铵溶液为滴定剂,测定土壤中有机质含量。优化后的分析条件:溶样温度为220℃,溶样时间为(5.5±0.5) min,催化剂用量为0.08 g。对3个国家一级标准物质进行分析,测定结果与推荐值相符,相对误差为–4.0%～0.0%,相对标准偏差为1.17%～3.66%(n=6)。该法可用于大批量土壤样品中有机碳含量的快速测定。     

王水回流溶样-火焰原子吸收光谱法测定地质样品中的金

建立王水回流溶样聚氨酯泡沫塑料吸附火焰原子吸收光谱法测定地质样品中金的分析方法。在传统法使用锥形瓶王水溶样的基础上,在磨口锥形瓶上增加回流装置,以长15 cm的玻璃管作为冷却回流管,加入30mL王水溶液(1+1)对样品进行消解,采用火焰原子吸收光谱法测定。金的质量浓度在0～4.00μg/mL范围内与吸光度呈良好的线性关系,相关系数为0.999 3,检出限为0.058μg/mL。金矿石标准物质测定结果的相对标准偏差为2.75～6.41%(n=6),相对误差为–5.00%～0.61%;5种不同矿区金矿石样品测定结果的相对标准偏差为2.02%～9.24%(n=9)。该方法样品消解完全,减少了王水的使用量和氮氧化物的排放,操作简便,结果准确可靠,适用于地质样品的批量分析。     

振荡抽滤-pH计指示电位滴定法快速测定土壤样品中阳离子交换总量

为了提高土壤中阳离子交换量(CEC)分析效率及分析准确度,采用乙酸铵或氯化铵-乙酸铵溶液对土壤样品进行处理,并采用振荡交换、抽滤分离的方式进行离子交换、铵离子清洗。土壤饱和吸附的铵离子用甲醛-CaCl2溶液交换后,采用氢氧化钠溶液滴定,并用pH计准确指示滴定终点,由此测定CEC含量。选用5个国家一级有效态标准物质进行验证,测定值与推荐值相符,相对标准偏差均小于7%,提高了CEC的分析效率与准确度,更加适用于大批量样品的测定。     

原子吸收光谱法测定金银样品前处理的讨论

讨论了在岩石、矿物及化学探矿样品中金、银的原子吸收光谱分析时,样品前处理应关注的一些问题实践经验表明要注意样品的加工过程和金银的赋存状态,以保证样品有足够的代表性;针对不同矿种类型,选择合适的样品前处理方法,尽量避免样品在处理过程中的挥发损失、包夹、共沉淀吸附等情况的发生;对单矿物金、银的连续测定,建议采用多次湿法酸处理来保证样品的分解,并根据其含量进行必要的分离富集或稀释,以满足测定的要求．     

凯氏定氮法测定土壤中水解性氮样品处理条件的三维响应曲面优化

利用三维响应曲面法优化LY/T 1228—2015测定土壤中水解性氮含量的实验条件。为了缩短反应时间,提高检测效率,使用三维响应曲面法对碱解蒸馏法的蒸馏条件进行优化,并据此建立凯氏定氮仪直接测定土壤中水解性氮含量的方法,优化后的实验条件:NaOH溶液的浓度为2.7 mol/L,蒸汽比率为100%,蒸馏时间为5 min。测定结果的相对标准偏差为1.76%～2.64%(n=5),优于碱解扩散法(2.66%～3.61%)。对3个国家一级标准物质进行测定,测定结果与推荐值相符。与标准方法相比,该方法成本低,可操作性强,特别适用于土壤环境质量评价、地区土壤抽样调查等大批量土壤样品分析。     

Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents

In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium and gold ions in the digested samples were pre-column derivatized with HNATR to form colored chelates. The Pd-HNATR, Pt-HNATR, Rh-HNATR and Au-HNATR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] with a buffer solution of 0.05 mol L(-1) phosphoric acid as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and travelling towards the analytical column. These chelates separation on the analytical column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] was satisfactory with 72% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of Triton X-100) as mobile phase. The palladium, platinum, rhodium and gold chelates were separated completely within 2.5 min. Compared to the routine chromatographic method, more then 80% of separation time was shortened. By on-line solid phase extraction system, a large volume of sample (10 mL) can be injected, and the sensitivity of the method was greatly improved. The detection limits (S/N=3, the sample injection volume is 10 mL) of palladium, platinum, rhodium and gold in the original samples reaches 1.4, 1.8, 2.0 and 1.2 ng L(-1), respectively. The relative standard deviations for five replicate samples were 2.4-3.6%. The standard recoveries were 88-95%. This method was applied to the determination of palladium, platinum, rhodium and gold in human urine, water and geological samples with good results.     

Determination of polycyclic aromatic hydrocarbons with molecular weight 302 in water samples by solid-phase nano-extraction and laser excited time-resolved Shpol'skii spectroscopy

Monitoring of high-molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) via simple and cost effective methods still remains a challenge. In this article, we combine solid-phase nano-extraction (SPNE) and 4.2 K laser-excited time resolved Shpol'skii spectroscopy (LETRSS) into a valuable alternative for the water analysis of dibenzo[a,l]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. In comparison to the original SPNE procedure, the present method improves PAH recoveries and reduces extraction time from 30 to 20 min per sample. Quantitative release of HMW-PAH into the Shpol'skii matrix (n-octane) is best accomplished with a mixture of 48 μL of methanol and 2 μL of 1-pentanethiol. Their migration into the 50 μL layer of n-octane provides highly resolved spectra with distinct fluorescence lifetimes for unambiguous isomer determination. Complete analysis takes less than 30 min per sample and consumes only 100 micro-liters of organic solvents. 500 μL of water are sufficient to obtain limits of detection ranging from 16 ng L(-1) (dibenzo[a,l]pyrene) to 55 ng L(-1) (dibenzo[a,i]pyrene), relative standard deviations better than 3% and analytical recoveries above 90%. Although a straightforward comparison to chromatographic methods is not possible because of the lack of analytical figures of merit on HMW-PAH, the excellent precision of measurements, limits of detection and overall recoveries makes SPNE-LETRSS an attractive approach to water analysis of HMW-PAH.     

低温焙烧-原子吸收法测定高含量辉锑矿中的金

采用先低温焙烧除硫后再高温焙烧,通过王水溶样,对辉锑矿矿样焙烧方法的对比表明,利用方法焙烧样品,矿样不结块,金可溶解完全.方法经国家一级标准物质分析验证,结果与标准值相符.对实际样品测定的方法精密度为1.44%～4.79%(RSD,n=5).加标回收率在95.5%～104.3%,方法快速、准确,适用于高含量辉锑矿中金的批量样品分析.     

响应面法优化巴旦木壳对废水中Pb、Cu和Cd的吸附及同时测定

研究废弃巴旦木壳对模拟废水中Pb、Cu和Cd的去除率。在单因素实验的基础上,采用响应面法对吸附剂投加量、吸附时间和pH值3因素进行优化。实验结果表明,Pb、Cu和Cd分别在最佳吸附吸附剂投加量0.4 g,吸附时间49.38 min,pH值为9.96;吸附剂投加量0.4 g,吸附时间49.91 min,pH值为10.13;吸附剂投加量0.4 g、吸附时间49.83 min、pH值为10.42的条件下,去除率分别为87.42%、73.49%和85.11%。采用偏最小二乘法(PLS)对Pb、Cu和Cd模拟混合试样吸附后的溶液测定的曲线进行拟合回归,计算得出吸附剂对Pb、Cu和Cd的去除率分别为83.2%、66.0%和83.3%。用PLS对吸附后的模拟废水样品进行计算分析,并间接得出巴旦木壳对Pb、Cd和Cu的去除率和建立Pb、Cd、Cu三组分同时测定的多元校正分析方法。     

Modification of catalytic adsorptive stripping voltammetric method of hexavalent chromium determination in the presence of DTPA and nitrate

The voltammetric procedure for determination of traces of Cr(VI) [Anal. Chim. Acta (1992) 262:103] was modified by changing the temperature of the measurements. It was found that at the temperature of 40 °C the time of decrease of the Cr(III) signal was shortened from 30 to 5 min. As a result the total analysis time was drastically shortened. The modified procedure does not show any disadvantage as compared to the original method. The results of Cr(VI) determination by the modified procedure are less affected by Cr(III) as compared to the original method. The detection limit of the method was 2.5 × 10^-11 mol L^-1 (1.2 ng L^-1). The validation of the modified procedure was performed by comparison of the results of analyses of tap and river water samples with those obtained using original procedure.     

Analysis of gallium arsenide by spark-source mass-spectrometry

A method has been developed for analysing gallium arsenide with a resistance of greater than 10(9)Omega by spark-source mass-spectrometry, without the need for pelleting, which introduces a prohibitively high level of contamination and lowers the detection limit for a given exposure. It uses a gold evaporation technique, whereby a thin layer of 99.999% pure gold is deposited on one surface of the GaAs electrodes, in a chamber mounted on the ion-source. No contamination, other than gold, is introduced into the sample at a level of 50 ng/g or greater. It is possible to detect carbon in the sample at the 1-2 mug/g level. The sample preparation time is less than 30 min, and more than one set of samples can be gold-coated at a time.     

Flow-through stripping chronopotentiometry for the monitoring of mercury in waste waters

A simple method for the determination of total mercury in waste waters is described. It makes use of a flow system incorporating a wall-jet cell equipped with a gold working electrode. The untreated sample is mixed on-line with the acidic carrier electrolyte which contains potassium permanganate and transforms the various species of mercury, especially elementary Hg, to Hg(II). The pre-treated solution enters the cell where mercury is deposited on the gold electrode. In the next step the deposit is stripped at constant current and the time corresponding to the dissolution of the deposit is obtained from the chronopotentiometric signal. The method enables it to determine and monitor Hg in the concentration range of 1 to 1000 μg/L in 5 min intervals. Received: 20 October 1997 / Revised: 23 December 1997 / Accepted: 30 December 1997     

Flow-through stripping chronopotentiometry for the monitoring of mercury in waste waters

A simple method for the determination of total mercury in waste waters is described. It makes use of a flow system incorporating a wall-jet cell equipped with a gold working electrode. The untreated sample is mixed on-line with the acidic carrier electrolyte which contains potassium permanganate and transforms the various species of mercury, especially elementary Hg, to Hg(II). The pre-treated solution enters the cell where mercury is deposited on the gold electrode. In the next step the deposit is stripped at constant current and the time corresponding to the dissolution of the deposit is obtained from the chronopotentiometric signal. The method enables it to determine and monitor Hg in the concentration range of 1 to 1000 μg/L in 5 min intervals. Received: 20 October 1997 / Revised: 23 December 1997 / Accepted: 30 December 1997     

Raman spectroscopic and density functional theory studies on a benzothiazole-2-thione derivative

The two tautomers of 7H-[1,3]dioxolo[4′,5′,4,5]benzo[1,2-d]thiazole-6-thione (DBTT) have been investigated by FT-IR and FT-Raman combined with density functional theory (DFT) calculations at the B3LYP level and 6-311+G** basis sets. On the basis of optimized structures, the harmonic force fields, vibrational frequencies and Raman intensities were calculated and scaled. The assignment of the fundamental vibrations for this molecule in its thione form was performed according to the potential energy distribution (PED) analysis. We have also discussed the adsorption behavior of DBTT on gold by means of SERS and DFT calculations at the same level. It revealed that the DBTT exhibited stable conformation of benzothiazole-2-thione (BTT) form both in solid and on gold surfaces; in addition, DBTT molecule is chemisorbed to the gold through both N and the exocyclic S atoms in its thione form and its molecular plane is perpendicular to the surface as BTT. The results show that the substituted groups in the phenyl ring have changed the characters such as the charge density in heterocyclic atoms and so on, but have little influence on the tautomeric preference of the BTT molecule and adsorption orientation on gold.     

Direct determination of benzo[a]pyrene in water samples by a gold nanoparticle-based solid phase extraction method and laser-excited time-resolved Shpol'skii spectrometry

The strong affinity between polycyclic aromatic hydrocarbons (PAH) and the surface of gold colloids is investigated to device an extraction method for water samples. Within the 20-100 nm particle diameter range, the 20 nm gold nanoparticles showed the best extraction efficiencies for all the studied analytes. The new approach is combined to laser-excited time-resolved Shpol'skii spectrometry for the direct analysis of benzo[a]pyrene in drinking water samples. For a 500 μL sample volume, the analytical figures of merit demonstrate precise and accurate analysis at the parts-per-trillion level. The extraction efficiencies are statistically equivalent to 100% with relative standard deviations lower than 2%. The average recoveries were varied from 87.5% to 96.5% for different concentration of analytes. The simplicity of the experimental procedure, the low analysis cost, and the excellent analytical figures of merit demonstrate the potential of this approach for routine analysis of drinking water samples.