Abstract: Disclosed is a sampling method and apparatus in which sampling is accompanied by the steps of inducing a sample to flow into an outer chamber and excluding the sample from an inner chamber by inducing a first pressure zone in the inner chamber such that a substantially discrete interface between the first pressure zone and sample is formed at an orifice between the outer chamber and inner chamber; sufficiently reducing the first pressure zone in the inner chamber to induce the sample to flow through the orifice between the outer chamber and inner chamber and into the inner chamber such that first pressure zone-sample interface is substantially undisturbed when it moves through the orifice between the outer chamber and inner chamber; inducing the sample to flow from the inner chamber into an inner tube having an orifice within the inner chamber which forms a pathway to a detector such that the first pressure zone-sample interface remains substantially undisturbed; inducing a second pressure zone in the inner c