An apparatus and method that allow multiple samples of a liquid in a primary container to be taken with minimal danger of contaminating the liquid in the container during the sampling process are disclosed. Low or zero plasticizer content eliminates any significant occurrence of problems such as increased stiffness and longitudinal shrinkage. The stimulation circuit is configured to deliver electrical stimulation pulses through the first and second pairs of electrodes. The handle can actuate the pump either using a piston or a lever motion.