A sampler for taking samples from multiple sources has a fixed, non-moving needle at a sampling station. A sample vial is lifted from a tray at the sampling station. The needle pierces the septum of the vial and enters the sample as the vial is lifted toward the needle. The sample vial is also rotated as it is lifted, and a bar code reader makes a number of spaced apart, helical reads on a bar code label attached to the vial for label identification of the sample. The needle includes an inner, sample needle and an outer, gas-pressurization needle. The sample is withdrawn by the positive displacement of a syringe connected to the sample needle. The combination of the gas pressurization within the vial and the positive displacement of the syringe insures movement of the sample and accurate control of the volume removed independent of the viscosity of the sample. The vial tray mechanism for carrying the sample vials to and from the sample station includes a rotatable platter and four planetary trays carried by and rotatable on the platter. A clutch and brake drive permits the entire tray assembly to be rotated as a unit and also permits rotation of the planetary trays relative to the main platter so that any sample vial can be positioned at the sample station in any desired sequence with respect to the other sample vials.