An apparatus comprising: one or more reaction vessels each coupled to a respective electronic sensor for monitoring products in each of the one or more reaction vessels, the electronic sensor configured to generate an output signal related to a concentration or presence of a product, the output signal depending on a reference voltage; a fluidics system for sequentially delivering a plurality of electrolytes to the one or more reaction vessels one at a time, the fluidics system comprising: a plurality of electrolyte reservoirs configured to store the plurality of electrolytes ; a common passage configured to fluidicly connect the plurality of electrolyte reservoirs to the one or more reaction vessels ; and a wash solution reservoir fluidicly connected to the common passage via a branch passage ; wherein the branch passage includes a valve disposed between the wash solution reservoir and a junction with the common passage , the apparatus further comprising a reference electrode , characterized in that said reference electrode is disposed in the branch passage between the valve and the junction such that the reference electrode is in fluid and electrical contact with a wash solution disposed within the branch passage and in fluid communication with the one or more reaction vessels coupled to the respective electronic sensor and in electrical communication with the one or more reaction vessels via the wash solution and at least one of the plurality of electrolytes , the reference electrode further being configured to provide the reference voltage to each electronic sensor without the reference electrode being in fluid contact with any of the plurality of electrolytes . one or more reaction vessels each coupled to a respective electronic sensor for monitoring products in each of the one or more reaction vessels, the electronic sensor configured to generate an output signal related to a concentration or presence of a product, the output signal depending on a reference voltage; a fluidics system for sequentially delivering a plurality of electrolytes to the one or more reaction vessels one at a time, the fluidics system comprising: a plurality of electrolyte reservoirs configured to store the plurality of electrolytes ; a common passage configured to fluidicly connect the plurality of electrolyte reservoirs to the one or more reaction vessels ; and a wash solution reservoir fluidicly connected to the common passage via a branch passage ; wherein the branch passage includes a valve disposed between the wash solution reservoir and a junction with the common passage , the apparatus further comprising a plurality of electrolyte reservoirs configured to store the plurality of electrolytes ; a common passage configured to fluidicly connect the plurality of electrolyte reservoirs to the one or more reaction vessels ; and a wash solution reservoir fluidicly connected to the common passage via a branch passage ; wherein the branch passage includes a valve disposed between the wash solution reservoir and a junction with the common passage , the apparatus further comprising a reference electrode , characterized in that said reference electrode is disposed in the branch passage between the valve and the junction such that the reference electrode is in fluid and electrical contact with a wash solution disposed within the branch passage and in fluid communication with the one or more reaction vessels coupled to the respective electronic sensor and in electrical communication with the one or more reaction vessels via the wash solution and at least one of the plurality of electrolytes , the reference electrode further being configured to provide the reference voltage to each electronic sensor without the reference electrode being in fluid contact with any of the plurality of electrolytes . <EOS>