Suddenly having problems attaching proteins to glass microscope slides, to make microarrays or biosensors? Check your tools! If you bought the slides after 2008, then you’ll find them much harder to work with than the pre-08 versions.

Chris Taitt and colleagues, who work at the Naval Research Laboratory, in Washington D.C., discovered that slides bought after 2008 are smoother and lower in magnesium than those purchased before that date.

It’s not a trivial difference: the researchers spotted a “dramatic reduction in biomolecule immobilization efficiency” (Analytical Chemistry, DOI:10.1021/ac902324r). Why the magnesium and roughness should affect the chemistry that’s used to attach proteins to slides, the researchers aren’t yet sure.

“This paper reminds scientists wondering why their analytical data is not as good as that obtained by their predecessors to confirm the quality of even the simplest of their starting materials,” another NRL scientist, Frances Ligler, tells Chemical and Engineering News, which runs this interesting story. The magazine asked slide-makers Thermo Fisher Scientific about the issue, but the company told them that they hadn’t changed their production process, and hadn’t received reports from customers of performance differences.