A method of detecting a location of a surface of a sample in a container, the method comprising: coupling an input signal to one of a probe and an outer surface of the container; moving at least one of the container and the probe relative to one another such that the probe is directed into the container; detecting an output signal from the other of the probe and the outer surface of the container that is not coupled to the input signal; generating a processed signal as a function of the output signal; comparing the processed signal to a contact threshold; and determining that the probe has contacted the sample surface when the processed signal is at least equal to the contact threshold level, Z wherein the container has a cover/septum, and the method further comprises: (a) applying the input signal with a contact frequency f p to either the probe or an outer surface of the container and to the cover/septum; (b) comparing the processed signal to a first threshold level less than the contact threshold level and determining when the processed signal is greater than or equal to the first threshold level; (c) measuring a distance the at least one of the container and the probe has moved since it was detected that processed signal was greater than or equal to the first threshold level; (d) ceasing movement of the container and the probe relative to one another if the measured distance exceeds a safety distance and the processed signal has not been determined to be greater than or equal to the contact threshold; and(e) determining that the probe has contacted the sample surface when the processed signal is at least equal to the contact threshold level. coupling an input signal to one of a probe and an outer surface of the container; moving at least one of the container and the probe relative to one another such that the probe is directed into the container; detecting an output signal from the other of the probe and the outer surface of the container that is not coupled to the input signal; generating a processed signal as a function of the output signal; comparing the processed signal to a contact threshold; and determining that the probe has contacted the sample surface when the processed signal is at least equal to the contact threshold level, Z wherein the container has a cover/septum, and the method further comprises: (a) applying the input signal with a contact frequency f p to either the probe or an outer surface of the container and to the cover/septum; (b) comparing the processed signal to a first threshold level less than the contact threshold level and determining when the processed signal is greater than or equal to the first threshold level; (c) measuring a distance the at least one of the container and the probe has moved since it was detected that processed signal was greater than or equal to the first threshold level; (d) ceasing movement of the container and the probe relative to one another if the measured distance exceeds a safety distance and the processed signal has not been determined to be greater than or equal to the contact threshold; (a) applying the input signal with a contact frequency f p to either the probe or an outer surface of the container and to the cover/septum; (b) comparing the processed signal to a first threshold level less than the contact threshold level and determining when the processed signal is greater than or equal to the first threshold level; (c) measuring a distance the at least one of the container and the probe has moved since it was detected that processed signal was greater than or equal to the first threshold level; (d) ceasing movement of the container and the probe relative to one another if the measured distance exceeds a safety distance and the processed signal has not been determined to be greater than or equal to the contact threshold; and(e) determining that the probe has contacted the sample surface when the processed signal is at least equal to the contact threshold level.