The present invention is a system and method for providing a passive diffusion bag sampler that is suitable for obtaining concentrations of a variety of volatile organic compounds, wherein the passive diffusion bag sampler includes an outer protective rigid mesh tube, an inner polyethylene bag disposed inside the outer protective rigid mesh tube, a ring coupled to and disposed at either end of the outer protective rigid mesh tube, a cap also disposed at either end of the outer protective rigid mesh tube and inside the ring but over the inner polyethylene bag and forming a watertight seal, and a non-removable plug disposed in an aperture through each of the caps, wherein the passive diffusion bag sampler may be held and poured using a single hand because of the rigidity of the passive diffusion bag sampler.

In various examples, an apparatus, system, and method for focusing particles within a two-dimensional suspended fluidic flow are described. A fluid is passed through a two-dimensional channel. The fluid contains particles. An acoustic signal is provided through the fluid channel substantially perpendicular to the two-dimensional fluid flow to align the particles. Characteristics of the particles within the flow, including amount and/or distribution, are determined via optical techniques. Other apparatuses, systems, and methods are disclosed.