the second lid 54 is removed to provide access to the opening 100 in the elution chamber 42 the pipette 124 is inserted into the opening 100 and the prepared sample of nucleic acid is withdrawn as shown in fig1 a multi channel pipette 126 may be used to access a plurality of samples from a plurality of cassettes 10 fig2 illustrates an alternative embodiment of the cassette 10 the cassette 10 a illustrated in fig2 differs from the cassette 10 illustrated in fig1 in that the assembly component 104 a includes a seal 130 the plungers 24 a 26 a 28 a and 30 a each include seals 132 134 136 and 138 respectively and the valves 32 a 34 a and 36 a have a different arrangement as discussed hereinafter fig2 illustrates the assembly component 104 a in more detail the assembly component 104 a includes a seal 130 the illustrated seal 130 is a double elastomer which extends along the circumference of the assembly component 104 a fig2 illustrates the plunger 24 a in more detail the plunger 24 a includes a seal 132 the illustrated seal 132 is also a double elastomer which extends along the circumference of the plunger 24 a it will be appreciated that each of plungers 26 a 28 a and 30 a may also have a similar arrangement fig2 and 24 illustrate.