Pencil lead as a matrix for MALDI-ToF mass spectrometry of sensitive functional polymers

With the increase in complexity of functional polymers in recent years, MALDI-ToF has become an important tool for gaining precise information on polymer functionality, end groups, and, in special cases, molecular weights. Here we describe how pencil lead, deposited by simply drawing with a regular pencil onto conventional MALDI-ToF targets, can be used as a very attractive matrix for MALDI-ToF mass spectrometry of synthetic polymers. Highly sensitive polymers such as silyl hydride functional poly(styrene), poly(butadiene), and poly(isoprene) have been investigated using conventional MALDI-ToF matrices as well as pencil lead. In all cases, the use of pencil lead prevented oxidation of the highly sensitive silyl hydride end groups. It is shown that pencil lead represents an interesting alternative to the commonly used matrices in the range between 400 and 6000 g/mol due to the convenient way of deposition, its low cost, nontoxicity, and chemical inertness under sample preparation conditions.