bids are invited for ph 4.0 buffer tablet - analytical grade or proprietary buffer tablets, each capable of making 100 milli litres of buffer solution at ph 4.0 plus or minus 0.02 when dissolved in deionized or distilled water at 25 degree , typically contain potassium hydrogen phthalate or standard mixtures as per cpcb or is or bis references , ph 7.0 buffer tablet - analytical grade or proprietary buffer tablets, each making 100 milli litres solution at ph 7.0 plus or minus 0.02 at 25 degree, common constituents are mixtures of potassium dihydrogen phosphate and disodium hydrogen phosphate or certified proprietary blends, conforming to bis specifications for water analysis , ph 9.2 buffer tablet - analytical grade or proprietary tablets, producing 100 milli litres buffer solution at ph 9.0 plus or minus 0.02 at 25 degree, typically based on borax or certified mixtures to cpcb protocol, dissolved in deionized water , potassium chloride - analytical reagent grade or equivalent potassium chloride with a minimum purity of 99 percentage, supplied in airtight, moisture resistant hdpe or amber glass bottles, with batch number and expiry date clearly marked to preserve integrity, should comply with is or bis or apha or astm standards for water analysis and be certified for use in laboratory calibration and analysis , filter paper pore size 2 to 2.5 micro meter or equivalent to whatmann filter no.542 - circular discs, pore size 2 to 2.5 micrometers, made of refined cotton linters with 95 percentage cellulose, ash content 0.1 percentage, and wet strengthened, equivalent to whatman number 542 with the diameter of 90 millimeter or 125 millimeter , silica gel desiccant - granular or bead form with particle size 2 to 5 millimeters, pore size 2.0 to 2.5 nanometers, water adsorption capacity 27 percentage, ph 5 to 8 slurry, and loss on drying 5 percentage at 150 to 180 degree celcius , supplied in moisture proof sealed containers with batch certification , tissue paper - high abs