procurement of standard solutions for chemical laboratory of ph-ivstps,sarni. , items , ph buffer standard solution (4.0 ph) certified reference material (crm) , ph buffer standard solution (7.0 ph) certified reference material (crm) , ph buffer standard solution (9.2 ph) certified reference material (crm) , conductivity 147 ?s/cm standard solution certified reference material (crm) , conductivity 1413 ?s/cm standard solution 250c certified reference material (crm) , conductivity 12.88 ?s/cm standard solution certified reference material (crm) , silica standard solution 1.00 mg/liter sio2 in h2o certified reference material (crm) , silica standard solution 0.50 mg/liter sio2 in h2o certified reference material (crm) , silica standard solution 0.10 mg/liter sio2 in h2o certified reference material (crm) , calcium standard solution (1000 mg/liter) certified reference material (crm) , magnesium standard solution (1 ppm) certified reference material (crm