Matrix-assisted laser desorption/ionization, fast atom bombardment and plasma desorption mass spectrometry of polyethylene glycol esters of (2-benzothiazolon-3-yl)acetic acid
ABSTRACT Fast atom bombardment (FAB), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and plasma desorption (PD) mass spectra of newly synthesized polyethylene glycols (PEGs), (M(w) 600-4000 Da) chemically modified with biologically active (2-benzothiazolon-3-yl)acetyl end-groups are described (products 1-6). The spectra were also used for the determination of the molecular mass characteristics (number average (M(n)) and weight average (M(w)) molecular masses) of the initial and modified PEGs. As expected, M(n) and M(w) of the modified samples are higher than those of the non-modified samples. However, it is shown that molecular mass dispersity (determined by the comparison of the polydispersity indices (PDI = M(w)/M(n)) of both types of PEGs) essentially do not change during this modification. The FAB mass spectra, together with molecular species, show the presence of abundant [M + Na](+) ions of product 1 and [M + Na + H](+) species of 2 and 3, and [M + Na + 2H](+) of product 4. Two main series of fragment ions, derived from the cleavage of the ether bonds, are observed. The number fractions of the molecular adduct ions and fragment adduct ions, determined from the FAB and PD mass spectra of the modified PEGs, are compared. The MALDI-TOF mass spectra of compounds 1-6 show the presence of two series of polymers. The most abundant peaks are due to [M + Na](+) and [M + K](+) ions originating from the polymers, in which the two terminal hydroxyl groups of PEGs are esterified with (2-benzothiazolon-3-yl)acetic acid. The less abundant peaks are due to the monosubstituted polymers.
- SourceAvailable from: Maurizio S Montaudo
Article: Mass spectra of copolymersMass Spectrometry Reviews 01/2002; 21(2):108-44. DOI:10.1002/mas.10021 · 8.05 Impact Factor
- Analytical Chemistry 07/2002; 74(12):2743-8. DOI:10.1021/ac020214u · 5.83 Impact Factor
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ABSTRACT: The use of organometallic fragments as cationization reagents for matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of polystyrene (PS) and polypropene (PP) is reported. Reaction of [Ru(C5H5)(NCCH3)3][PF6] (1a) with PS samples of numerical mass average Mn 1430–135 000 in a ratio [Ru]/[PS]=1/1 to 3/1 favours effective ionization of the polymer by MALDI-MS techniques and leads to an increase in signal intensity over that obtained by use of Ag+ salts. PP samples of Mn 2700 and 6100 are ionized after reaction with the trinuclear ruthenium pentahydride derivative (RuC5Me5)3H5, thus affording the first observation of MALDI-MS signals for this polymer. Reactions of the cations [Ru(C5H5)(NCCH3)3]+ and [Ru(C5Me5)(NCCH3)3]+ with 1,3-diphenylpropane and of (RuC5Me5)3H5 with 1-eicosene were studied as models for the corresponding reactions with PS and PP, respectively.Journal of Organometallic Chemistry 12/2002; 663(1):213-220. DOI:10.1016/S0022-328X(02)01770-9 · 2.30 Impact Factor