Attograms, Zeptograms and Yoctograms

The measurement of the mass of a protein molecule, on the zeptogram (10-21 g) scale, is now possible, as can be read on New Scientist.com. Previously, in 2000, the mass of a cluster of gold atoms, near one attogram (10-18 g) was already measured. The next goal, a gigantic step, is to develop devices capable of weighing masses on the yoctogram (10-24 g) scale, meaning measuring the mass of a single hydrogen atom. The article is worth reading as is this one, published on PhysOrg.