Fig. 4. Individual analysiswaspreparedforeachsensorinthearrayoftype1.Therootmeansquareerrorofcross-validation(RMSECV)foreachPLS-Rmodelusing asingle
sensor asavariable(graybar)wascomparedtotheRMSECVwhenallsensorswereanalyzed(whitebar).Errorbarsrepresenttwicethestandarddeviation frommea-
surements usingthreedifferentarrayspreparedwiththesameprocedure.Thesecomparisonsweretestedforthereferencechemicalandbiologicalparameters:(a)
Microtox®, (b)Algaetest,(c)BOD,(d)COD,and(e)TOC