supply and delivery crm chemicals to 31 dist . labs of twad board supply and delivery crm ( certified reference materials ) chemicals to 31 dist . labs of twad board , supply and delivery of the following certified reference materials- chemicals to 31 district laboratories of twad board . including packing , transportation charges , loading , unloading , stacking charges and transit insurance charges etc complete . , buffer solution - ph 7 . 0 , 100 ml ( 1x 31 nos . ) , buffer solution - ph 4 . 0 , 100 ml ( 1x 31 nos . ) , buffer solution - ph 9 . 2 , 100 ml ( 1x 31 nos . ) , sodium carbonate volumetric standard , 80 g ( 1x 31 nos . ) , sulphuric acid 1 n , 1000 ml ( 1x 31 nos . ) , calcium carbonate volumetric standard , 50 g ( 1x 31 nos . ) , sodium chloride volumetric standard , 80 g ( 1x 31 nos . ) , fluoride standard solution , 500 ml ( 1x 31 nos . ) , sulfate standard solution , 500 ml ( 1x 31 nos . ) , nitrate standard solution , 500 ml ( 1x 31 nos . ) , potassium chloride 0 . 147 ms/cm , 30 ml ( 1x 31 nos . ) , silver nitrate solution 0 . 1 n , 500 ml ( 1x 31 nos . ) , hydrochloric acid 1 n , 500 ml ( 1x 31 nos . )