Hello Peter
We use the following criteria (see table) for acceptability of our pipettes.
It has been around for a while, I don't know the origin of this set of
criteria,
it looks a bit tighter than the figures you mentioned,
and service and check interval is 3 months.
If it helps to relieve the tedium at all, I could send you my Excel file.
This does automatic lookup of water density,
and provides a continuous compact record (1 line per check, as many readings
as you like) of each pipette.
(see below: figures in red are calculated by cell formulae. Remainder are
typed in by the operator.)
Regards
Richard Scarff
Biochem Dept
Royal Perth Hospital
Western Australia
Pipette assessment:
* Accuracy and precision must fall within the following limits:
Volume (m L)
Accuracy (mL)
Precision (SD)
20
0.0196 - 0.0204
<0.0002
25
0.0246 - 0.0254
<0.0002
30
0.0296 - 0.0304
<0.0003
50
0.0495 - 0.0505
<0.0003
100
0.0993 - 0.1007
<0.0005
150
0.1490 - 0.1510
<0.0008
200
0.1986 - 0.2014
<0.0010
250
0.2480 - 0.2520
<0.0015
300
0.2970 - 0.3030
<0.0020
400
0.3960 - 0.4040
<0.0020
500
0.4960 - 0.5040
<0.0020
1000
0.9940 - 1.0060
<0.0050
5000
4.9700 - 5.0300
<0.0080
Gilson pipette D18214G "LIP3" (Variable, 1000uL)
File:
L:\Lipids\PIPCHECK\[LPGILSON.XLS]LIP1
password:
Standard protocol:use new tips for each weighing(New/Same), Touch side of
weighing container (T/NT). Note any variations in 'operator field, eg: rs
S,NT)
serial
Date
Operator
Temp oC nn.n
Setting
Corrected Average volume (uL)
SD (uL)
CV%
Pipette Error%
Weighings ... (max 50) ............ 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
21
21/09/2001
rs (nt, s)
22
1000
1010.72
0.0017
0.166
1.072359
NA P
1.0119
1.0090
1.0083
1.0089
1.0094
1.0065
1.0097
1.0101
1.0090
1.0070
1.0051
1.0079
1.0087
1.0075
22
21/09/2001
mc
22.1
1000
1002.71
0.0010
0.102
0.270601
a p
1.0001
0.9985
0.9997
1.0003
1.0000
1.0016
1.0016
1.0003
1.0018
1.0009
23
21/09/2001
mc
22.1
500
502.53
0.0011
0.229
0.505121
a p
0.5013
0.5011
0.5010
0.4993
0.5010
0.5011
0.5021
0.5033
0.5009
0.5030
-----Original Message-----
From: Galloway, Peter [mailto:[log in to unmask]]
Sent: Friday, 14 November 2003 07:43
To: [log in to unmask]
Subject: Re: Pipette checks
Please help me with my ignorance.
Is there a sensible regime for pipette checks in terms of the frequency of
checks and the required accuracy.
All I can find is a German standard DIN 12650 which suggests 3 monthly
checks and an error limit of 1.5 ul at 100ul and 10ul at 1000ul
This seems a lot of work. Is there a more reasonable standard which would be
acceptable to the majority ?
Peter Galloway
Royal Hospital for Sick Children
Glasgow
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