高分辨连续光源石墨炉原子吸收光谱法测定原油中挥发性和非挥发性钒化合物

Amethodisproposedthatmakespossibledeterminingtotaland“thermallystable”vanadiumincrudeoilwithoutpriorseparation,andtocalculate“volatile”vanadiumbydifference.Thevolatilefractionisbelievedtobelargelyvanadylporphyrinecomplexes.Themethodisbasedontheunsurpassedbackgroundcorrectioncapabilityofhigh-resolutioncontinuumsourcegraphitefurnaceatomicabsorptionspectrometry(HR-CSGFAAS),whichallowspyrolysistemperaturesaslowas300◦Ctobeused.Thesampleswerepreparedasoil-in-wateremulsions,andaqueousstandardsemulsifiedinthesamewaywereusedforcalibration.Totalvanadiumhasbeendeterminedusingapyrolysistemperatureof400◦C,and“thermallystable”vanadiumusingapyrolysistemperatureof800◦C.Thecontentoftotalvanadiumin12Braziliancrudeoilsampleswasfoundtobebetweenlessthan0.04andabout30mgkg−1.Thevolatilefractionwasbetween5and51%ofthetotalcontent,andtherewasnocorrelationbetweenthetotalandthevolatilevanadiumcontent.Thelimitsofdetectionandquantificationwere0.04and0.12mgkg−1ofVincrudeoil,respectively,basedonamassof2gofoilin10mLofemulsion.Theprecisionwasbetterthan4%atthe3mgkg−1levelandbetterthan1.5%atthe30mgkg−1levelofVincrudeoil.