The development and proliferation of quasi-1D nanomaterials has evolved far more rapidly than the measurement science necessary to characterize these once exotic species. As a result, there exists a grand challenge to develop methods that address the separation and quantitative characterization of purity, physical dimensions and composition (both intrinsic and surface functional species) in high aspect nano-objects. Among commercially available instruments for separation, asymmetric flow field flow fractionation (A4F) is perhaps one of the most broadly adaptable fractionation methods for nanoscale-to-microscale particles. A4F, hyphenated with online detectors (i.e. UV-Vis, MALS, DLS, etc.), provides reliable size information and fractionation in complex populations and without a stationary phase. The advantages offered by tandem separation and characterization methods by field flow fraction, are mainly due to their non-disruptive nature, fast throughput, and in-situ analysis. Here we discuss using A4F as a size and surface coverage characterization technique for gold nanorods (AuNRs) and introduce preliminary results for the separation and size characterization of single wall carbon nanotubes (SWNTs).