ANALYSIS OF METALS IN CONDENSATES AND NAPHTHA BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

condensates and naphtha are petroleum samples with largely gasoline-ra nge components (C-5-C-10), Metal organic complexes are source inherite d components of oils which are associated with the polar components an d asphaltenes of oils, Because of the very low levels of biomarkers su ch as hopanes and steranes in condensates, they present a special corr elation problem, Geochemically significant metals, such as V and Ni, c an be measured In some condensates using conventional Meinhardt-Scott chamber inductively coupled plasma mass spectrometry (ICP-MS), In orde r to increase the sensitivity and the range of condensates which can b e analysed, the Cetac U-6000 AT Ultrasonic nebuliser-desolvation syste m was tested, The Cetac system improved the sensitivity for V and Ni b y a factor of about 40. Valuable information for relating these diffic ult samples to each other and to heavier oils in a basin can thus be s upplied to exploration geochemists. The influence of organic matrix on the analytical signal was investigated, Matrix effects are more prono unced for the Cetac system than for the conventional ICP-MS system, Fo r both systems, the use of an In internal standard was found to be nec essary for compensating for differences in nebulisation and combustion behaviour caused by variations in the nature of the sample, The use o f ICP-MS for the analysis of toxic metals such as Bg and Pb in condens ates and naphthas is also discussed, The results are compared with tho se obtained using electrothermal atomic absorption spectrometry and co ld vapour atomic absorption spectrometry in an interlaboratory study o f naphthas, conventional Meinhardt-Scott chamber ICP-MS provided good accuracy and precision of analysis compared with the other techniques during this study, Volatile species such as Et4Pb and Me2Hg were lost in the desolvation unit when using the Cetac system. Volatilisation ef fects were nut observed when using the conventional Meinhardt-Scott ch amber ICP-MS system.