Ostermann Markus, Kettisch Peter, Becker Dorit, Vogl Jochen
Federal Institute for Materials Research and Testing (BAM), Unter den Eichen 87, 12205, Berlin, Germany.
Anal Bioanal Chem. 2003 Oct;377(4):779-83. doi: 10.1007/s00216-003-2127-3. Epub 2003 Aug 19.
Graz University of Technology has developed a new technique for digesting samples using the well-established high-pressure asher (HPA) from Anton Paar GmbH (Graz, Austria). The digestion is performed in semi-open vessels inside a pressurised autoclave. The new HPA equipment consists of a liner for the autoclave, special sample racks and 30-mL digestion vessels made of quartz, covered with PTFE stoppers. The Laboratory for Isotope Dilution and Nuclear Analysis of the Federal Institute for Materials Research and Testing (BAM, Berlin) tested this new equipment in order to assess its usability for the decomposition of larger sample amounts of gas oils for the measurement of sulfur. Several experiments were carried out using the new sample decomposition technique. In order to test the recovery of the new digestion method, a gas oil material with known sulfur content was chosen, quantified by the validated conventional closed vessel HPA digestion in combination with thermal ionisation mass spectrometry. Isotope dilution mass spectrometry has been applied as analytical method in this investigation. The gas oil was spiked with an isotopic spike material, which is enriched in (34)S, and was then wet digested in the HPA. The oxidized sulfur of the dried samples was reduced to H(2)S and precipitated as As(2)S(3). The sulfur was measured as arsenic monosulfide (AsS(+)). The mass content of sulfur in the gas oil tested is 453.5 mg kg(-1). Recovery tests for increasing masses of gas oils indicate that the recovery using the new measurement technique decreases with increasing mass of gas oil. Results were obtained for approximately 0.3 g sample weight and had less overlap with the result of the old HPA method within the stated uncertainties. At approximately 0.5 g sample weight the yield decreases to about 97% and at approximately 1.0 g sample weight to about 87%. In comparison with the conventional closed vessel HPA digestion, the new technique shows no clear advantages for the certification of the sulfur content in gas oil other than a more convenient handling. The total uncertainty of the sulfur mass fractions (k=2) is about 1.5%. Repeated determination of the oil samples show a relative standard deviation of about 0.8% and indicate that the analytical procedure is robust and reproducible. The demonstrated reproducibility allows the establishment of correction factors for the yield, which in turn enables higher sample masses for routine work. The blank level (0.26 x 10(-6) g) was within the range of the conventional closed HPA digestion procedure.(0.28 x 10(-6) g). Cross contamination could not be detected. In terms of trace metal analysis a good applicability and more advantages over the conventional closed vessel HPA digestion can be assumed.
格拉茨工业大学利用奥地利格拉茨安东帕有限公司成熟的高压灰化仪（HPA）开发了一种新的样品消解技术。消解在高压灭菌器内的半开放式容器中进行。新型HPA设备包括高压灭菌器的内胆、特殊样品架以及由石英制成的30毫升消解容器，容器配有聚四氟乙烯塞子。联邦材料研究与测试研究所（德国柏林材料测试研究院，BAM）的同位素稀释与核分析实验室对该新设备进行了测试，以评估其用于分解大量瓦斯油以测定硫含量的适用性。使用新的样品分解技术进行了多项实验。为测试新消解方法的回收率，选择了一种已知硫含量的瓦斯油材料，通过经验证的传统密闭容器HPA消解结合热电离质谱法进行定量分析。本研究采用同位素稀释质谱法作为分析方法。向瓦斯油中加入富含(34)S的同位素标样，然后在HPA中进行湿消解。干燥样品中的氧化硫被还原为H₂S，并沉淀为As₂S₃。硫以一硫化砷（AsS⁺）形式进行测定。所测试的瓦斯油中硫的质量含量为453.5毫克/千克。对增加瓦斯油质量的回收率测试表明，使用新测量技术的回收率随瓦斯油质量增加而降低。对于约0.3克的样品重量获得了结果，在规定的不确定度范围内与旧HPA方法的结果重叠较少。在约0.5克样品重量时，回收率降至约97%，在约1.0克样品重量时降至约87%。与传统密闭容器HPA消解相比，除了操作更方便外，新技术在瓦斯油硫含量认证方面没有明显优势。硫质量分数的总不确定度（k = 2）约为1.5%。对油样的重复测定显示相对标准偏差约为0.8%，表明分析程序稳健且可重复。所展示的可重复性允许建立回收率的校正因子，这反过来又能在常规工作中使用更高的样品质量。空白水平（0.26×10⁻⁶克）在传统密闭HPA消解程序的范围内（0.28×10⁻⁶克）。未检测到交叉污染。就痕量金属分析而言，可以假定该方法具有良好的适用性，并且比传统密闭容器HPA消解更具优势。
