bids are invited for certified reference material sor -1 ph buffer solution - potassium hydrogen phthalate of ph-4 at 25 deg. c - standard for ph analysis 2 ph buffer solution - potassium hydrogen phthalate/disodium hydrogen phosphate of ph-7.0 at 25 deg. c - standard for ph analysis 3 ph buffer solution - boric acid/potassium chloride/sodium hydoxide of ph-10 at 25 deg. c - standard for ph analysis 4 standard for sulphide s-2 content analysis - potassium dichromate volumetric standard, secondary reference material for redox titration, traceable to nist 5 standard for sulphide s-2 content analysis - sodium sulphide nona hydrate - sulphide s-2 content 6 standard for total suspended solid tss, celite-545, particle size 0.02-0.1 mm 7 standard for total suspended solid tss, sigmacell cellulose type 20 8 standard for chemical oxygen demand cod - 100 ppm ,packing size 9 standard for chemical oxygen demand cod - 200 ppm, packing size 10 standard for chemical oxygen demand cod - potassium hydrogen phthalate 11 standard for biological oxygen demand - glucose 12 standard for biological oxygen demand -glutamic acid 13 standard for biological oxygen demand - analogue en 1899 standard solution 210 mg/l 14 standard for oil and grease stearic acid 15 standard for oil and grease - hexadecane analytical standard, 5ml 16 standard for phenol analysis , certified reference material crm , 1gm 17 iron standard solution -1000 mg/l fe, fe(no3)2 in hno3 0.5 mol/l 18 silicon standard solution - 1000 mg/l si, (nh4)2sif6 in h2o 19 zinc standard solution -1000 mg/l zn, zn(no3)2 in hno3 0.5 mol/l 20 water standard at 0.01% for coulometric karl fischer titration total quantity : 78