Patent ID: 8877513

Claim:
A method of using a disposable pipette tip with a pipetting system, the method comprising the steps of: providing a disposable pipette tip comprising a barrel having a lower opening, through which liquid is aspirated into the barrel and dispensed from the barrel, an upper portion having an inside surface with a circular circumference and an upper end having a circular circumference and an inside diameter, the disposable pipette tip also comprising a collar having a continuous inner surface with a circular circumference in its relaxed state, an upper opening of the collar for receiving a tip mounting shaft on the pipetting system, and a lower end of the collar with a circular circumference in its relaxed state and an inside diameter that is larger than the inside diameter of the upper end of the barrel, and a circumferential shelf connecting the lower end of the collar to the upper end of the barrel; providing at least one tip mounting shaft on the pipetting system, the tip mounting shaft including an internal bore through which air is displaced in order to aspirate liquid sample into and dispense liquid sample from the pipette tip, said tip mourning shaft having a lower sealing section, an upper locking section, a stop located between the upper locking section and the lower sealing section, two or more outwardly extending lobes located above the stop and spaced circumferentially around the upper locking section, and recessed relief portions spanning circumferentially between the lobes and recessed relative to the lobes; inserting the mounting shaft into the tip collar so that the collar of the disposable pipette tip flexes and distorts outwardly as it engages the lobes cm the mounting, shaft and inwardly at the recessed relief portions on the mounting shaft between the lobes such that the collar is distorted out of round; continuing to insert the mounting shaft into the tip collar until the mounting shaft is fully inserted into the collar such that the stop on the mounting shaft engages the circumferential shelf on the disposable pipette tip; maintaining roundness of the circular circumference of the inside surface of the upper portion of the barrel when the mounting shaft is fully inserted into the tip collar; and sealing the inside surface of the upper portion of the barrel against the lower sealing section of the mounting shaft when the mounting shaft is fully inserted into the disposable pipette tip.