Electrochemical measuring

In a method for analyzing fluid samples using an electrochemical measuring apparatus having an analyzing device with an inlet port and an outlet port, said outlet port connecting with an outlet tube, said inlet port connecting to an inlet tube having a sample-receiving end, and said inlet tube connecting at a junction along its length to one end of a fluid supply tube having two ends, said one end and an opposite end, which fluid supply tube is connected at its opposite end to at least one fluid source and which fluid supply tube initially is filled with fluid calibrant, the improvement comprising, a method for isolating the fluid calibrant in the fluid supply tube from fluid drawn proximally through the inlet tube past the junction and to the analyzing device by creating and maintaining an air bubble in the fluid supply tube at the junction by drawing a segment of air from said inlet tube into said fluid supply tube to isolate the fluid calibrant in the fluid supply tube from the junction,

• putting the sample-receiving end of the inlet tube in contact with a fluid sample,
• and exerting a force to draw the fluid sample proximally through the inlet tube.

In an electrochemical measuring apparatus having an analyzing device with an inlet port and an outlet port, said outlet port connecting to an outlet tube, said inlet port connecting to an inlet tube having a sample fluid receiving end, and said inlet tube connecting at a junction along its length to one end of a fluid supply tube having two ends, said one end and an opposite end, which fluid supply tube is connected at its opposite end to at least one fluid source containing a fluid, a method comprising,

• causing said fluid from said supply source to flow through said fluid supply tube to said junction and causing said fluid to flow simultaneously in a proximal direction and a distal direction within the inlet tube from the junction, and
• causing a fluid sample to flow through the inlet tube past the junction and into the analyzing module.

In a method for analyzing fluid samples using an electrochemical measuring apparatus having an analyzing device with an inlet port and an outlet port, said outlet port connecting with an outlet tube, said inlet port connecting to an inlet tube having a sample-receiving end, and said inlet tube connecting at a valveless junction along its length to one end of a fluid supply tube having two ends, said one end and an opposite end, which fluid supply tube is connected at its opposite end to at least one fluid source, and said device having a first peristaltic pump disposed at a point along the length of the fluid supply tube and a second peristaltic pump disposed at a point along the length of the outlet tube, the improvement comprising, a method for introducing intermittently spaced air bubbles into the fluid at the valveless junction as the fluid passes from the fluid supply tube through the valveless junction and proximally through the inlet tube, said last mentioned method comprising,

• operating said second peristaltic pump to create a continuous proximal drawing force in said inlet tube, and
• operating said first peristaltic pump intermittently to introduce into said inlet tube segments of fluid, said segments being spaced apart by air in the inlet tube.