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Filling and using a volumetric (or graduated) pipette Why do this? The use of a pipette is essential for delivering accurate volumes of liquid and carrying out volumetric analysis. It is important that the correct handling of the apparatus is carefully taught. The technique needs patience and regular practice by both the teacher and the student. The use of different types of pipette filler is described. Possible curriculum links: quantitative , analysis, Suitability Y7 Personal protective equipment and essential safety measures Wear eye protection. The level of eye protection required will depend on the chemicals used. Filling a pipette should only be carried out using a pipette filler to avoid any risk of ingestion of chemicals. Do not pipette by mouth. Fillers must be fitted to pipettes with care or the will be broken and may cause an injury. Regardless of the type of pipette filler, hold the pipette at the top and carefully insert it into the filler by pushing gently. This Practical Procedure should be read in conjunction with the following guidance: • Relevant Hazcards for the chemicals used • Handbook Section 10 Outline method and control measures Filling the pipette using a filler 1. Hold the pipette at the top and carefully insert it into the rubber bulb filler. 2. Pinch valve A and squeeze bulb to expel all the air inside. 3. Place the tip of the pipette in the solution and squeeze valve B. The liquid should rise up the pipette. Ensure the tip of the pipette remains in the liquid otherwise air bubbles are sucked up and liquid can be drawn into and contaminate the filler bulb (see Disposal). 4. Release valve B when the level of liquid is above the graduation mark on the pipette. 5. Gently squeeze valve C to lower the liquid level. Lower the liquid until the bottom of the meniscus is level with the graduation mark. View the graduation mark at eye level. 6. Carefully move the pipette to the intended receptacle (eg, conical flask) and firmly squeeze valve C to expel the liquid from the pipette.

PP 0007 02/14 ©CLEAPSS®, The Gardiner Building, Brunel Science Park, Kingston Lane, Uxbridge UB8 3PQ Page 1 of 2 Tel: 01895 251496; Fax: 01895 814372; E-mail: [email protected]; Web site: www.cleapss.org.uk Filling the pipette using a Pi-pump 1. Hold the pipette at the top and carefully insert it into the Pi-pump by pushing gently and rotating slightly. 2. Place the tip of the pipette in the solution. Use the thumbwheel to raise the level of liquid to above the graduation mark on the pipette. Ensure the tip of the pipette remains in the liquid otherwise air bubbles are sucked up and liquid can be drawn into and contaminate the filler (see Disposal). 3. View the graduation mark at eye level. Lower the liquid until the bottom of the meniscus is level with the graduation mark. 4. Carefully move the pipette to the intended receptacle (eg, conical flask) and expel the liquid using the release lever valve.

Filling the pipette using a syringe 1. Attach a syringe to the top of the pipette with silicone tubing. The syringe should be of greater volume than the volume of the pipette. 2. Place the tip of the pipette in the solution. Raise the barrel of the syringe to raise the level of liquid to above the graduation mark on the pipette. 3. Quickly remove the rubber tubing and syringe and place your forefinger (or thumb) over the top of the pipette. 4. View the graduation mark on the pipette at eye level. Adjust the pressure of the forefinger (or thumb) to lower the liquid until the bottom of the meniscus is level with the graduation mark. 5. Carefully move the pipette to the intended receptacle (eg, conical flask). Expel the liquid from the pipette by releasing your finger/thumb. Disposal If solutions have accidently been sucked into the filler, students should hand the filler to the teacher or technician for cleaning. The contaminated fillers should not be placed back in a storage drawer. The fillers can be rinsed in pure water to remove any reagents that might affect the materials. Rubber bulb fillers should be allowed to dry fully open (i.e. not depressed as in the image). Additional information The is a precision and delicate instrument and subject to National and International standards which are engraved on the glass. ‘B’ standard pipettes are sufficiently accurate for school work. Tags pipette, titration

PP 0007 02/14 ©CLEAPSS®, The Gardiner Building, Brunel Science Park, Kingston Lane, Uxbridge UB8 3PQ Page 2 of 2 Tel: 01895 251496; Fax: 01895 814372; E-mail: [email protected]; Web site: www.cleapss.org.uk