A clinical tester has been described that includes a probe to aspirate a fluid. The expressions are further derived from reducing error of curve fitting HETP empirical data of various columns by using the defined HETP to obtain expressions for the vapor-side and liquid-side mass transfer coefficients and mass transfer area. The wager cancellation link may also be enabled for certain events occurring at certain venues. One bidirectional port pair of the optical switch is set into a loop back configuration, without setting the remaining bidirectional port pairs into the loop back configuration. By providing a portable hand sanitizing station that may be removably mounted to a supporting structure, the present invention provides a hand sanitizer apparatus that may be quickly and easily deployed in the field to provide a temporary hand sanitizing station capable of dispensing a significant quantity of hand sanitizer.