GB11901-89 Determination of Suspended Substance [PDF]

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Water quality-Determination of suspended substance-Gravimetric method



Water quality-Determination of suspended substance -Gravimetric method GB 11901-89 Approved on: 1989-12-25



Implemented on: 1990-07-01



1 Scope and Application This test method covers the determination of suspended substance in water. This test method is applicable to the determination of suspended substance in surface, underground waters, domestic and industrial wastes. 2 Definitions Suspended substance in water is defined as the sum of residue on the 0.45μm pored membrane when the sample being filtered through a glass filter, and that residue shall be dried to a constant weight at 103～105℃. 3 Reagents Distilled water or water with equivalent purity 4 Equipment and apparatus 4.1 Equipment normally used in laboratory and the following apparatus 4.2 Glass filters with Millipore membrane 4.3 CN－CA membrane, pore size: 0.45μm, grid diameter: Φ60mm 4.4 Vacuum pump or aspirator 4.5 Forceps, smooth-tipped 5 Sample collection and Storage 5.1 Sample collection For those polyethylene bottles or glass bottles that would be used later, use detergent to clean them, then rinse them by tap water and distilled water in turn, wash them with three portions of sample water again before sampling, plug them tightly after sampling 500-1000ml waters into them. Note: Non-homogenous floating particles or submerged flocculent materials shall be excluded from the samples because they are not suspended substance.



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Water quality-Determination of suspended substance-Gravimetric method



5.2 Storage of sample Sample analysis should begin as soon as possible. If preservation is unavoidable, the sample should be placed in a 4℃ refrigeration, and the storage time should not exceed 7 days. Note: To avoid the risk of destroy of the balance between solid substances and liquid substances, it is prohibited to add any protective material into the sample. 6 Procedure 6.1 Preparation of membrane Use forceps to move membrane into the weighted weighing bottle. Dry weighing bottle in an oven at 103～105℃ for at least half an hour. Cool filter in a desiccator to room temperature. When cool, weigh the weighing bottle. Repeat the above steps of drying, cooling and weighing until weight loss of the weighing bottle is less than 0.2mg. Remove the membrane into the membrane filter, place it on the membrane support dish in a correct way. Cover the membrane filter with accessorial funnel and fix it with clips. Apply suction to membrane with a small amount of distilled water and continue that process. 6.2 Sample Analysis procedure Mix sample well and pour into a graduated cylinder to the selected volume 100ml. Pour selected volume into filtration apparatus and apply suction until sample has completely passed through. Rinse graduated cylinder into filtration apparatus with three successive 10ml portions of distilled water, allowing complete drainage between each rinsing. Remove all traces of water by continuing to apply vacuum after sample has passed through. Use forceps to remove membrane now containing suspended solids with weighted weighing bottle. Dry weighing bottle in an oven at 103～105℃ for at least an hour. Cool filter in a desiccator to room temperature. When cool, weigh the weighing bottle. Repeat above steps of drying, cooling and weighing until weight loss of the weighing bottle is less than 0.4mg. －2－



Water quality-Determination of suspended substance-Gravimetric method



NOTE: For samples with extremely high solids concentrations, excessive moisture may be entrained with them, causing not only the established drying time being prolonged, but also the hardness to filter out, in such case, use a larger filter to ensure a representative sample volume can be filtered. Normally, the sample volume should be within 5-100mg suspended solids. 7 Calculations To determine the value of total suspended solids in mg/L, the following calculation should be used:



Where: C——Concentration of suspended substance in water，mg/L； A——Weight of suspended substance + membrane + weighing bottle，g； B——Weight of membrane + weighing bottle，g； V——Volume of sample filtered, mL.



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