微波加热测定硅酸盐矿石样品的烧失量

分别以微波加热和传统加热两种方法测定某些标准样品和管理样品的烧失量。通过试验表明，微波加热法取代传统加热法测定样品的烧失量，不仅有较高的准确度和精密度，还可以大大缩短测定时间，提高测定效率，节能效果也十分显著。     

粉煤灰烧失量测定方法探讨

按照标准GB/T 1596–2005中方法检测粉煤灰烧失量,发现存在检测结果为负值的现象,为了解释该现象,完善针对该类粉煤灰烧失量的检测方法,以及给出该检测方法的适用条件,分别按照标准GB/T 176-2008和GB6730.8–1986对灼烧[(950±25)℃]前后粉煤灰中硫化物和亚铁含量进行测定,同时对灼烧后粉煤灰的颜色不同进行分析。结果表明,粉煤灰中亚铁是引起粉煤灰烧失量为负值的主要原因,亚铁含量与灼烧后粉煤灰颜色有一定相关性,对于灼烧后为红棕色的粉煤灰,应对灼烧前粉煤灰中亚铁含量进行测定,视其对烧失量的影响程度,决定是否对烧失量进行校正。     

热重分析法测定矿产品中的吸附水及烧失减量

采用热重分析法(TGA)测量矿产品中的吸附水及烧失减量,验证了方法的准确性及精密度。对多种矿产品样品采用TGA法和常规马弗炉加热法进行测量,对比结果表明,这两种方法没有显著性差异。TGA法具有方便快捷、准确可靠等优点,是矿产品吸附水及烧失减量检验的首选。     

浅析铝土矿烧失量的差异在X-射线荧光光谱分析中造成的影响刘静,马慧侠,彭展,白万里

本文探讨了一水铝土矿与三水铝土矿烧失量的差异在X-射线荧光光谱分析中造成的影响。采用试验的方式考察了硼酸锂熔融制样过程中铝土矿的烧失量损失情况;运用理论计算分析了烧失量的损失对测量结果的影响。试验与理论分析结果表明：当采用一水铝土矿绘制工作曲线来测量三水铝土矿样品时,将导致三水铝土矿中各组分测量结果偏高;烧失量的差异对主量元素测量结果影响较大,而对微量元素测量结果影响较小;待测物质的烧失量与基准物质烧失量差异越大,测量结果的偏差也就越大。     

太湖沉积物中酮的提取、分离及GC-MS测定

用索氏抽提法提取了太湖沉积物中的可溶性有机质,用不同极性溶剂在硅胶／氧化铝柱上分离了饱和烃,芳烃,酮馏分。利用ＧＣ－ＭＳ对酮组份进行了分析。沉积物中检出了一系列呈等间距分布的正构烷基－２－酮：Ｃ１４至Ｃ３３,主峰为Ｃ２９,具有强烈的奇碳数优势。     

环己酮氨肟化反应中失活TS-1催化剂上沉积物的物化表征

在液相环己酮氨肟化反应中,有机物在钛硅分子筛催化剂（TS-1）上的沉积是造成失活的原因之一。采用傅里叶变换红外光谱、热重-差热、色谱-质谱联用、X-射线衍射、固体核磁共振、N2物理吸附和扫描电镜等分析手段,对失活TS-1的骨架结构及表面沉积物分子的结构和物化性质进行了表征。结果表明,引起催化剂失活的沉积物富集在分子筛的孔道内,主要有环己酮的氧化或还原产物、环己酮的二聚物、环己酮肟深度反应产物、叔丁基环己酮等可溶性沉积物以及它们缩聚而成的不溶性沉积物,其量可占失活催化剂总质量的5.0%。TPO烧炭时靠近Ti中心处的沉积物可以在较低温度下脱除,而孔道内的其他沉积物需要在较高温度下脱除,650℃沉积的炭可完全脱除。失活催化剂经700℃煅烧再生后,催化活性可恢复到新鲜催化剂的水平。     

元素分析仪测定土壤、沉积物样品碳氮含量的影响因素及数据校正

使用元素分析仪进行土壤、沉积物样品碳、氮含量检测时,样品前处理过程(烘干和酸化)、包样质量以及参考标准品等因素均会对检测结果造成影响. 试验结果表明:酸化导致氮百分质量的测定结果降低2.6%~40.0%,碳百分质量的测定受包样质量的影响较大,使用的校正标准与被测样品越相似,校正结果越准确.     

重铬酸钾滴定法测定海洋沉积物中氧化亚铁的不确定度评定

根据GB/T 14506.14—2010,建立重铬酸钾滴定法测定海洋沉积物中氧化亚铁含量的不确定度评定方法.按照数学模型,计算出重铬酸钾滴定法测定海洋沉积物中氧化亚铁的含量.分析在测定过程中影响不确定度的各因素,包括基准物质的摩尔质量、纯度、称量过程、标准溶液配制过程、滴定过程的温度、玻璃量具体积、测量重复性等,对这些...     

湖泊沉积物中镉的测定及环境意义研究

建立了氢化物发生-原子荧光光谱法测定湖泊沉积物中镉的分析方法.优化了沉积物中镉的提取条件和测定条件,研究了Cu元素对测定镉的干扰及消除方法.以武汉市涨渡湖为例,通过对总镉和有效态镉的测定揭示了涨渡湖近百年来镉的各形态垂直分布特征.结果表明:自上世纪50年代以来,涨渡湖沉积物中的总镉由深层到表层呈上升趋势,有效态镉变化不大但其含量维持在较高水平.镉的潜在风险性较大.     

三种消解方法在测定近海沉积物中Pb、 Cu、 Cd、 Hg及As的应用

常压湿式消解、高压微波消解、常压微波消解3种方法被应用于近海沉积物中Pb、 Cu、 Cd、 Hg、 As 5种重金属元素的分析. 以近海海洋沉积物标准物质为样品经3种方法消解后, 通过石墨炉原子吸收法测定Pb、 Cu、 Cd和氢化物发生原子荧光法同时测定Hg、 As. 结果表明, 样品经常压湿式消解, 其Pb、 Cu、 Cd回收率在80%～123%内而Hg、 As回收率低;经高压微波消解, 标样中Pb、 Cu、 Cd、 As回收率在84%～117%内, 对Hg测定回收率偏低;常压微波消解更适合于Cu、 Cd、 Hg、 As的消解, 其回收率在95%～121%之间而Pb回收率低于42.4%. 常压湿式消解与常压微波消解被用于大亚湾人工渔礁区沉积物样品的处理, 有较好的测定结果.     

Characterisation and quantification of organic phosphorus and organic nitrogen components in aquatic systems: a review

This review provides a critical assessment of knowledge regarding the determination of organic phosphorus (OP) and organic nitrogen (ON) in aquatic systems, with an emphasis on biogeochemical considerations and analytical challenges. A general background on organic phosphorus and organic nitrogen precedes a discussion of sample collection, extraction, treatment/conditioning and preconcentration of organic phosphorus/nitrogen from sediments, including suspended particulate matter, and waters, including sediment porewaters. This is followed by sections on the determination of organic phosphorus/nitrogen components. Key techniques covered for organic phosphorus components are molecular spectrometry, atomic spectrometry and enzymatic methods. For nitrogen the focus is on the measurement of total organic nitrogen concentrations by carbon hydrogen nitrogen analysis and high temperature combustion, and organic nitrogen components by gas chromatography, high-performance liquid chromatography, gel electrophoresis, mass spectrometry, nuclear magnetic resonance spectrometry, X-ray techniques and enzymatic methods. Finally future trends and needs are discussed and recommendations made.     

Micro-focused ultrasonic solid-liquid extraction (muFUSLE) combined with HPLC and fluorescence detection for PAHs determination in sediments: optimization and linking with the analytical minimalism concept

Analytical minimalism is a concept that deals with the optimization of all stages of an analytical procedure so that it becomes less time, cost, sample, reagent and energy consuming. The guide-lines provided in the USEPA extraction method 3550B recommend the use of focused ultrasound (FU), i.e., probe sonication, for the solid–liquid extraction of Polycyclic Aromatic Hydrocarbons, PAHs, but ignore the principle of analytical minimalism. The problems related with the dead sonication zones, often present when high volumes are sonicated with probe, are also not addressed. In this work, we demonstrate that successful extraction and quantification of PAHs from sediments can be done with low sample mass (0.125 g), low reagent volume (4 ml), short sonication time (3 min) and low sonication amplitude (40%). Two variables are here particularly taken into account for total extraction: (i) the design of the extraction vessel and (ii) the solvent used to carry out the extraction. Results showed PAHs recoveries (EPA priority list) ranged between 77 and 101%, accounting for more than 95% for most of the PAHs here studied, as compared with the values obtained after soxhlet extraction. Taking into account the results reported in this work we recommend a revision of the EPA guidelines for PAHs extraction from solid matrices with focused ultrasound, so that these match the analytical minimalism concept.     

Spatial trends of petroleum hydrocarbons in water and sediments

Seasonal changes in petroleum hydrocarbons in water and streambed sediment from selected oil-related areas of Ondo State, Nigeria have been examined using gravimetric and infrared methods. The highest and lowest total petroleum hydrocarbon concentrations (TPH) in water (sediments in brackets) gravimetrically were 3.49 mg L⁻¹ (199.3) mg kg⁻¹ and 0.003 mg L⁻¹ (81.0) mg kg⁻¹ while the concentrations found by IR were 24.0 mg L⁻¹ (135.0 mg kg⁻¹) and 14.0 mg L⁻¹ (33.0 mg kg⁻¹) respectively. The two seasons were positively correlated (α = 0.01) by both methods. The TPH level was well correlated with the sediment organic carbon (OC) during both seasons. The characteristic carbonyl (C=O) vibrations at 1650 cm⁻¹ and 1700 cm⁻¹ indicate oxidation of the oil residue. The study recommends further investigation into the type of organics present to evaluate their toxicity and appropriate remediation.      

Investigation on spontaneous ignition of two kinds of organic material with water

A systematic investigation was performed to elucidate the cause of spontaneous ignition of Refuse Derived Fuel (RDF) and Meat Bone Meal (MBM). Heat generation in both RDF and MBM with addition of water liquid and vapor at room temperature was determined by isothermal calorimetry. Compared with water liquid, the heat of wetting by sorption of water vapor at 80% relative humidity and 25 °C was larger, which can raise the temperature of RDF and MBM more than 30 and 56 °C, respectively. Heat generation due to fermentation occurred and the temperature of RDF and MBM reached or exceeded 80 °C after 5 days for RDF and 4 days for MBM at 100% RH. The spontaneous ignition for RDF and MBM results from heat of wetting and fermentation at room temperature and a further exothermic reaction at higher temperature.     

Geochemical variability of copper and iron in Oman Margin sediments

An analysis of the geochemical distribution of selected trace metals among various geochemical phases of the sediments in the Oman Margin was carried out using a sequential extraction technique. The present study showed that most Cu in abyssal sediment is associated with only oxidisable mainly organic and sulphide bound metals with insignificant bound to exchangeable, carbonates, easily/moderately reducible fraction. The preservation of Cu in the sediments indicates the importance of primary production and upwelling in the overlying waters and an organic flux in the sedimentary deposition of open-ocean environments. The early diagenetically formed oxidisable mainly organic and sulphide fraction are not degraded and results in a pronounced association of Cu with organic fraction in the sediments of the Oman continental margin. The strong correlation between Cu, TOC and Fe oxides associated with the oxidisable fraction in one of the core indicates that it is likely to be the presence of sulphides.     

The simultaneous spectrophotometric determination of iron and of copper using I,IO-phenanthroline

The use of n-octanol as extracting solvent has been employed in a new procedure whereby 1, 10-phenanthroline provides a simultaneous separation and spectrophotometric determination of both iron and copper when present together. The method depends upon the extraction of the Cu(I) complex into the water-immiscible alcohol phase leaving the Fe(II) complex in the aqueous phase. The separation of the two phase system in one extraction to give a quantitative partition of copper and iron is a feature of the method. The Cu(I) complex with 1, 10-phenanthroline was previously thought to be inoperative using any known water-immiscible organic solvent. The corresponding use of 2,2'-dipyridine as a substitute for 1, 10-phenan-throline was investigated and found to be inadequate. The new procedure is the first disclosure that the ferroin functional group may serve as a Cu(I) specific in substitution for the cuproine functional group of such ligands as cuproine⁵, neo-cuproine8 and bathocuproine7. The new procedure has been demonstrated to give a high degree of precision and at the same time providing simplicity in manipulation.     

On-line two-dimensional liquid chromatography-tandem mass spectrometric determination of estrogens in sediments

The development of an on-line system for the simultaneous determination of α-estradiol, β-estradiol, estrone and 17α-ethynylestradiol in river sediments is described. The analytes were extracted from sediments by microwave-assisted extraction. A crude extract was directly analysed by a heart-cutting two dimensional high-performance liquid chromatography-ion trap-tandem mass spectrometry with an atmospheric pressure photoionization source operating in the positive mode. The method shows excellent performance in terms of accuracy, precision, and sensitivity. The accuracy of each estrogen was in the range of 98.8-107.1%. Intra-batch and inter-batch precisions were in the range of 6.2-7.0% and 8.3-9.5%, respectively. The limits of detection ranged from 90 to 250 pg g(-1). A significant reduction in the total analysis time and a reduction in sample manipulation are the main advantages of the proposed method. Finally, the method was applied on real sediment samples.     

Surfactant-mediated extraction of iron and its spectrophotometric determination in rocks, minerals, soils, stream sediments and water samples

An extraction spectrophotometric method for iron determination in rocks, minerals, soils, stream sediments and water samples has been developed. At pH 3-4, iron (III) forms a 1:2:1 ternary complex with thiocyanate and cetyltrimethylammonium bromide (Fe/SCN/CTAB) which is extracted into ethyl acetate. The readily formed purple complex is suitable for extraction spectrophotometric determination of iron in rocks and related materials from submicrogram to milligram levels. The method is free from any interference due to commonly associated ions present in the matrices of rock samples. The present method is at least fourfold more sensitive (ε=3.2×10⁴ l mol⁻¹ cm⁻¹) than the conventional thiocyanate method and, in addition to the enhanced sensitivity and selectivity, it has got definite advantages over the corresponding binary thiocyanate system in terms of substantial improvement in the stability of the complex formed and broadening of Beer's law adherence range (0-6.0 mg/l). The method has been applied to a number of geological and hydrogeochemical samples for the determination of iron and the results obtained have been found to be favourably comparable with those obtained from the standard methods.