A two-step method for loading a fluid sample into a disposable fluid analysis cartridge is described. First, capillary action may be used to initially draw a sample through a sample introduction port and into a sample collection reservoir provided in the fluid analysis cartridge. Once the fluid sample has been drawn into the sample collection reservoir by capillary action, a negative pressure may be applied to the cartridge to pull the sample from the sample collection reservoir and into a sample loading channel. A valve may be disposed between the sample collection reservoir and the sample loading channel to prevent backflow of sample into the sample collection reservoir and to retain sample in the sample loading channel.