pipettes are instruments used to transfer liquid from one container to another they can transfer any volume and are usually used for volumes equal or less than 20 milliliters just in case you need to transfer more than 20 milliliters automatic pipettes are used pipettes could either be a glass pipette or an automatic pipette a glass pipette has parts the tip the stem and the mouth classification of pipettes according to type includes transfer pipette measuring pipette or graduated pipette micro pipette and automatic pipette transfer pipettes are designed to dispense one volume without further subdivisions pipettes classified as transfer pipettes are hostile fallen and volume trick pipette austral fallen pipettes has bulb like enlargement near the tip and are commonly used in dispensing viscous fluid or liquid volume trick pipettes has bulb like enlargement also at the middle of the stem and are usually used for delivering and transferring aqueous solution measuring or graduated pipettes are capable of dispensing several different volumes and has graduation lines along the stem pipettes classified as measuring pipettes or graduated pipettes are more serologic and micropipette more pipettes have no graduation marks to the tip and are calibrated between two marks serologic pipettes have graduation marks up to the tip and are calibrated up to the tip microp pets are pipettes which transfers liquid which are less than one milliliter examples of micrope pets are saul lee hellege pipette lang levy pipette rbc and wbc pipette and kirk and overflow pipette another classification of pipette as to type is automatic pipettes automatic pipettes from the term automatic imply that the mechanism of aspir rating and dispensing of fluid is inherited to the pipette it can be further classified according to mechanism and classification includes air displacement positive displacement and dispenser slash deliver pipette air displacement pipettes rely on piston for suction creation to draw the sample into a disposable tip and it uses disposable tip that is changed every after use positive displacement pipettes operates by moving the piston in the pipette tip or barrel much like a hypodermic needle and do not require a different tip each use [Music] how to use pipettes or perform the pending technique the pipette is held upright not an angle when using pipet the tip must be immersed in the intended transfer liquid to a level that will allow the tip to remain in solution after the volume of liquid has entered the pipet without touching the vessel wall by using a pipette bulb or similar equipment or instrument a slight suction is applied to the opposite end until the liquid enters the pipe head and the meniscus is brought above the desired graduation line and suction is then stopped speaking of meniscus meniscus could be lower or upper lower meniscus is used or to be followed if you are to transfer or deliver an aqueous and colorless liquid or fluid whereas an upper meniscus is used or to be followed if you are to transfer or deliver a viscous and a liquid or fluid with color first step on using pipette squeeze pipette bulb and touch it to the mouth of the pipet then hold the pipet by the upper third of the tube and keep the tip from touching anything then place the other end of the pipette in liquid to be transferred and slowly release pressure on bulb after that draw liquid up past desired level quickly replacing bulb with index finger let liquid drain until bottom of meniscus lines up with desired level on pipette then touch tip of pipette to inside a beaker to remove any adhering drops or you can wipe the tip of pipet with a laboratory tissue of any adhering liquid once removed transfer the liquid to the receiving vessel by touching the tip to inside a vessel and letting the liquid drain out of pipette in transferring liquid from pipette to receiving vessel the pipette should be held in a vertical position and the tip against the side of the receiving vessel and pipette contents are allowed to drain into the vessel the amount of liquid to be transferred will depend on how much volume of the liquid is needed or required [Music] you