Asphaltenes are still problematic fractions and their composition is not fully unveiled as it relates to the original crude oil and the precipitation method. In this work, the composition of asphaltenes precipitated with n-heptane and n-pentane from ten crude oils from the Sergipe-Alagoas Basin were assessed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) using five ionization procedures (electrospray ionization (ESI), ESI(+) with formic acid, ESI(-) with ammonium hydroxide, and ESI(-) with tetramethylammonium hydroxide, and atmospheric pressure photoionization (APPI), APPI(+) and APPI(-)) in combination with a 7.2 T LTQFT Ultra Thermo Fisher spectrometer. The purpose was to evaluate compositional differences between C5- and C7-asphaltenes according to the adopted ionization methodologies. Asphaltenes were compared as a function of heteroatomic composition and aromaticity. Chemometrics strategies were employed to evaluate the heteroatom classes of higher variation among the groups. Ions that were shared by the asphaltenes and the crude oils and between the ionization methods were also evaluated for similarity. Results showed that n-heptane asphaltenes are more aromatic than n-pentane asphaltenes, which in turn were found to be more acidic and to display a higher heteroatomic complexity. Principal component analysis and the evaluation of shared ions showed that APPI(-) is able to detected asphaltene ions directly from the whole crude oil. It was also found that the use of different ionization methods with and without additives is fundamental to obtain more comprehensive chemical profiles in terms of classes and their constituents for crude oils and their asphaltenes and that the specific n-alkane used to precipitate asphaltenes leads to different chemical profiles.