{
    "abstract": "99M Tc (V)-d,l-HM-PAO complex is well-known radiopharmaceutical for regional cerebral blood flow imaging. The proposed modifications in exametazime, hexamethylpropyleneamine oxime (HM-PAO) (4,8-diaza-3,6,6,9-tetramethylundecane-2,10-dione bisoxime) synthesis, for reduction of intermediary reactant diiminebisoxime (DI) (4,8-diaza-3,6,6,9-tetramethylundecane-3,8-diene-2,10-dione bisoxime) concerned two reductants (NaBH(4) and KBH(4)), two solvents (ethanol and 2-propanol), and three mole ratios of reactant/reductants (1:1, 1:1.5, and 1:2). The simultaneous analysis of diastereo-enantiomeric HM-PAO content, as well as the content of starting DI, in different reduction mixtures were performed using chiral ligand-exchange chromatography (CLEC). The separation of the samples of investigated reduction mixtures, obtained in the second step of HM-PAO synthesis, has been accomplished by using an achiral sorbent (RP-18) and a chiral mobile phase (CMP) containing copper(II) complex with N,N-dimethyl-l-phenylalanine (l-DM-PhA) as initial complex for CLEC. With 12 different reduction conditions, the obtained ratios of diastereoisomers d,l-HM-PAO: meso-HM-PAO varied from 69.2:30.8 to 15.9:84.1, in comparison to the reduction in routine synthesis of HM-PAO which gives an equal mixture of diastereoisomers. The ternary mixed complexes formation recorded spectrophotometrically on addition of HM-PAO or DI to the mobile phase with binary complex Cu(l-DM-PhA)(2), due to the evidence of bathochromic shift of 46nm for lambda(max) with significant difference in absorptivity contributes to separation mechanism.",
    "authors": [
        {
            "affiliation": "Department of Radioisotopes, Vinca Institute of Nuclear Science, P.O. Box 522, Belgrade, Yugoslavia.",
            "firstname": "N",
            "initials": "N",
            "lastname": "Nikoli\u0107"
        },
        {
            "affiliation": null,
            "firstname": "D",
            "initials": "D",
            "lastname": "Veselinovi\u0107"
        },
        {
            "affiliation": null,
            "firstname": "S",
            "initials": "S",
            "lastname": "Vladimirov"
        },
        {
            "affiliation": null,
            "firstname": "K",
            "initials": "K",
            "lastname": "Karljikovi\u0107-Raji\u0107"
        },
        {
            "affiliation": null,
            "firstname": "H",
            "initials": "H",
            "lastname": "Lingeman"
        }
    ],
    "conclusions": null,
    "copyrights": null,
    "doi": "10.1016/S0731-7085(03)00551-X",
    "journal": "Journal of pharmaceutical and biomedical analysis",
    "keywords": [],
    "methods": null,
    "publication_date": "2004-03-12",
    "pubmed_id": "15013142",
    "results": null,
    "title": "Chiral ligand-exchange chromatography as the screening method for proposed modifications in exametazime synthesis to enhance diastereoselectivity.",
    "xml": "<Element 'PubmedArticle' at 0x788503e14bd0>"
}