Chang Samuel Hsu

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT17.alpha.(H)-21.beta.(H)-hopane as a conserved internal marker for estimating the biodegradation of crude oilRoger C. Prince, David L. Elmendorf, James R. Lute, Chang S. Hsu, Copper E. Haith, James D. Senius, Gary J. Dechert, Gregory S. Douglas, and Eric L. ButlerCite this: Environ. Sci. Technol. 1994, 28, 1, 142–145Publication Date (Print):January 1, 1994Publication History Published online1 May 2002Published inissue 1 January 1994https://pubs.acs.org/doi/10.1021/es00050a019https://doi.org/10.1021/es00050a019research-articleACS PublicationsRequest reuse permissionsArticle Views1295Altmetric-Citations357LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of C60 and C70 clustersD. M. Cox, S. Behal, M. Disko, S. M. Gorun, M. Greaney, C. S. Hsu, E. B. Kollin, J. Millar, J. Robbins, and Cite this: J. Am. Chem. Soc. 1991, 113, 8, 2940–2944Publication Date (Print):April 1, 1991Publication History Published online1 May 2002Published inissue 1 April 1991https://pubs.acs.org/doi/10.1021/ja00008a023https://doi.org/10.1021/ja00008a023research-articleACS PublicationsRequest reuse permissionsArticle Views1432Altmetric-Citations251LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The presence of naphthenic acids in crude oils is of concern in the petroleum industry due to their corrosivity to refinery units. It is desirable to determine the ring type and carbon number distributions because the corrosivity of naphthenic acids is dependent on the sizes and structures. The characterization of naphthenic acids is also of interest to geochemical studies, particularly migration and biodegradation, and to refinery wastewater treatment for environmental compliance. We have evaluated chemical ionization, liquid secondary ion mass spectrometry (fast ion bombardment), atmospheric pressure chemical ionization (APCI), and electrospray ionization in both positive and negative ion modes for the determination of molecular distribution of acids without derivatization. Negative-ion APCI using acetonitrile as a mobile phase yields the cleanest spectra with good sensitivity among the ionization techniques evaluated. The selectivity of negative-ion APCI for naphthenic acids has also been demonstrated by comparing results for a whole crude oil with those for the isolated acid fraction. APCI also holds a great potential for on-line liquid chromatography−mass spectrometric (LC/MS) to separate acids by high-performance liquid chromatography (HPLC) followed by mass spectrometric characterization of acids.