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changes occur if the test is made immediately through a flow cell than if the water is exposed to <br /> air for a long period of time prior to measurements. <br /> B.12.4. Apparatus <br /> • Flow-through cell <br /> • Stoppers, fittings, valves, and tubing, as required <br /> • Conductivity, pH, and temp meters, or combination probe. <br /> B.12.4.1. Procedure <br /> • Connect the pump outlet to the inlet of the flow cell. <br /> • Insert the calibrated electrodes) into the flow cell and connect tubing to the outlet of the <br /> flow cell. <br /> • Turn on the pump and follow procedure for purging well. <br /> • Monitor parameters until within allowed ranges. Log the readings. <br /> • Take samples if scheduled. <br /> • Turn off the pump and disconnect the tubing. <br /> B.12.4.2. Procedure Bias <br /> The flow rate through the cell shall not be more than 1 liter per minute (L/m). If flow rates <br /> exceed 1 L/m, streaming potentials could occur. Streaming potentials are caused by the static <br /> charge effect of water moving through small openings. These potentials can cause erroneous <br /> pH readings. If necessary, reduce the flow rate or stop pumping to take readings. Note that <br /> Low-Flow Sampling Protocols may dictate even lower flow rates. To reduce the effect of <br /> temperature changes on the readings, the cell assembly, electrodes, and hoses should be <br /> insulated or kept out of direct sunlight. <br /> B.12.4.3. Quality Assurance <br /> The use of a closed flow-through cell should be noted on the sample documentation form or in <br /> the Field Log Book. <br /> Equipment blanks should be collected if equipment is field cleaned and re-used on-site or if <br /> necessary to document that low-level contaminants were not introduced by pumps, bailers or <br /> other sampling equipment <br /> B.13. Standard Practice for the Collection and Preservation of Liquid Samples <br /> B.13.1. Scope <br /> This procedure addresses the collection and preservation of liquid samples, including general <br /> collection procedures, collection of organics, and guidelines for sample preservation. Many <br /> factors should be considered during the sample collection phase: bottle type, bottle size, <br /> preservation, holding time, and order of sample collection. <br /> B.13.2. Terminology <br /> Meniscus— Is the curve of the upper surface of a liquid in a container. <br /> Daub &Associates, Inc. Page B-29 Natural Soda LLC 2022 SAP <br />