A new approach is proposed to determine component number in mixture. In this procedure, base vectors of measurement matrix are extracted by two methods respectively. The discrepancy between subspaces spanned by two sets of base vectors is measured. Examples in this note show that the proposed procedure can correctly determine the number of components for systems even with very similar spectral profiles. It is applied in the study of the self-association behavior of alcohol in CCI4. In this procedure, base vectors of measurement vectors are extracted by two methods respectively. The discrepancy between subspaces spanned by two sets of base vectors is measured. Examples in this note show that the proposed procedure is able to determine the number of components for systems even with very similar spectral profiles. It is applied in the study of the self-association behavior of alcohol in CCI4.