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1、BRITISH STANDARD BS 6018:1991 Method of test for Accuracy and precision of mechanical handpipettes of capacity 0.05 mL and above Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 This British Standard, having been prepared under t
2、he direction of the Laboratory Apparatus Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 20 December 1991 BSI 07-1999 First published January 1981 Second edition December 1991 The following BSI references relate to the work on this standa
3、rd: Committee reference LBC/27 Draft for comment 91/52111 DC ISBN 0 580 20229 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Laboratory Apparatus Standards Policy Committee (LBC/-) to Technical Committee LBC/27, upon which the followi
4、ng bodies were represented: Association of Clinical Biochemists British Glass Manufacturers Confederation British Laboratory Ware Association Department of Trade and Industry (Laboratory of the Government Chemist) Department of Trade and Industry (National Weights and Measures Laboratory) Institute
5、of Medical Laboratory Sciences Medical Sterile Products Association South Western Regional Health Authority Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 BSI 07-1999i Co
6、ntents Page Committees responsibleInside front cover Forewordii 0Introduction1 1Scope1 2Definitions1 3Apparatus1 4Reagent1 5Conditions of test1 6Procedure1 7Calculation and interpretation of results2 8Test report3 Table 1 Variation of the apparent density in air of distilled or deionized water with
7、temperature3 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 ii BSI 07-1999 Foreword This British Standard has been prepared under the direction of the Laboratory Apparatus Standards P
8、olicy Committee. It supersedes BS 6018:1981, which is withdrawn. This edition of the standard incorporates changes made as a result of experience gained in use of the 1981 edition and in the preparation of BS 7532, which covers handpipettes of capacity less than 0.05 mL and which was issued in 1986
9、as DD 154. The first edition was prepared, at the request of the Association of Clinical Biochemists, because of concern over the lack of a standard test method by which the accuracy and precision of mechanical handpipettes could be determined. This standard describes such a test method suitable for
10、 use both by users and by manufacturers of mechanical handpipettes. During the course of preparation of the test method a wide range of manufacturers sales literature has been examined and it has been noted that most manufacturers publish a figure for the accuracy, only, of their product. In a few c
11、ases coefficients of variation or precision are also mentioned. It is the view of the responsible committee that all manufacturers should publish figures indicating both the accuracy and the repeatability of their pipettes (see clause 7). It would be expected that such figures would vary with the si
12、ze of the pipette. To assist the user in comparing mechanical handpipettes, equations are provided in 7.2, 7.3 and 7.4 for the calculation of accuracy, standard deviation and coefficient of variation. A British Standard does not purport to include all the necessary provisions of a contract. Users of
13、 British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and a back
14、 cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 BSI 0
15、7-19991 0 Introduction In this test method the mechanical handpipette is tested under conditions as close as possible to those in which it is normally used. It is important to stress that the method described here tests pipette plus operator plus technique, for one pipette may seemingly perform diff
16、erently: a) with various operators; or b) with the same operator but under various conditions. Warmth transmitted by the hand to the mechanical handpipette during normal use may affect the performance of some pipettes. In order that any variation due to this might be seen it is recommended that the
17、instrument be neither pre-conditioned (warmed) before, nor isolated from handwarming during testing. 1 Scope This British Standard describes a method of test for determining the accuracy and precision of the volume delivered by mechanical handpipettes of capacity 0.05 mL1)and above in the temperatur
18、e range 16 C to 25 C. NOTE 1The method applicable to handpipettes of less than 0.05 mL capacity is described in BS 7532. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard, the following defin
19、itions apply. 2.1 mechanical handpipette a hand-held semi-automatic pipette with a detachable tip, used for transferring and dispensing a measured volume of liquid by displacement with or without an interface 2.2 accuracy (of a mechanical handpipette) the closeness of agreement between the nominal v
20、olume and the mean volume obtained by testing in accordance with this British Standard NOTEIt is quantified by the inaccuracy of the mean, expressed as a percentage error. 2.3 repeatability (of a mechanical handpipette) the closeness of agreement between the results of successive measurements of the
21、 same volume and carried out subject to all of the following conditions: a) the same method of measurement; b) the same observer; c) the same measuring instrument; d) the same location; e) the same conditions of use; f) repetition over a short period of time NOTERepeatability is expressed as the coe
22、fficient of variation (in %). 3 Apparatus 3.1 Analytical balance, capable of being read to 0.1 mg with a repeatability of 0.2 mg. NOTEA balance which tares rapidly is an advantage. 3.2 Water container, of 250 mL capacity. 3.3 Weighing vessel, having a capacity of between 4 and 10 times the volume of
23、 liquid that is to be weighed into it during the procedure. NOTEIt is important, especially for testing the smallest sizes of mechanical handpipettes that the ratio of height to diameter of the weighing vessel be as large as possible, and at least 3 : 1. 3.4 Stop watch or timer, accurate to 1 s. 3.5
24、 Thermometer, accurate to 0.1 C. NOTEA 0 C to 40.5 C, 100 mm immersion type thermometer, complying with BS 593 is suitable. 4 Reagent 4.1 Water, freshly distilled or deionized complying with grade 3 of BS 3978. 5 Conditions of test 5.1 Test room The test shall be carried out in a room with a stable
25、environment, with a relative humidity maintained at or above 45 % and at a temperature between 16 C and 25 C. 5.2 Cycle time The cycle time (see clause 6) shall be kept to a minimum and shall never exceed 60 s. 6 Procedure 6.1 Place the instruments to be tested in the test room 1 h before the test,
26、to enable them to reach equilibrium temperature. This shall be in the range 16 C to 25 C. 1) The millilitre is used for consistency throughout this standard, although it is recognized that some manufacturers employ other units of volume, such as the microlitre. Licensed Copy: sheffieldun sheffieldun
27、, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 2 BSI 07-1999 6.2 Do not alter the setting of an adjustable pipette during the weighing cycle. If using an adjustable pipette, set the capacity to the required value. NOTEHandpipettes of adjustable capacity should be t
28、ested at the manufacturers recommended maximum and minimum capacity values and at two or more intermediate capacity values, one of which should be below the mid-point of the range. 6.3 Pour not less than 200 mL of the water (4.1), previously kept in the test environment long enough to reach equilibr
29、ium temperature, into the water container (3.2) and note the temperature. 6.4 Place the weighing vessel (3.3) on the balance pan and record its mass. If the facility is available tare the balance. 6.5 Prepare the mechanical handpipette for the weighing cycle, fitting the tip recommended or supplied
30、by the manufacturer if appropriate, and filling and expelling water at least five times. After the final expulsion immerse the tip 2 mm to 3 mm into the water remaining in the container (3.2). 6.6 Fill the mechanical handpipette. After an interval of 5 2 s withdraw the tip of the mechnical handpipet
31、te from the water. Remove excess water from the outside of the tip by touching the wall of the container with the tip, allowing it to drain as recommended by the manufacturer. Expel the contents of the mechanical handpipette into the weighing vessel (3.3), with the tip of the pipette against the ves
32、sel wall and just above the surface of the water. Remove the tip of the pipette from the vessel and note the mass of the vessel and its contents. Carry out this weighing cycle 10 times. If the tare facility is available, use it after recording the value of each dose mass. NOTEA different weighing ve
33、ssel may be used for each weighing if desired, or the same vessel may be used for 10 successive weighings. 6.7 Record the final temperature of the water in the container (3.2) and calculate the mean test temperature. 7 Calculation and interpretation of results 7.1 Calculation of dose volumes 7.1.1 O
34、btain by subtraction 10 values for the mass of the dose dispensed by the mechanical handpipette. 7.1.2 Convert each dose mass to dose volume, x (in mL), by dividing it by the apparent density in air of water (in g/mL) at the mean test temperature (see Table 1). 7.1.3 Add the 10 volumes together and
35、divide their sum by 10 to obtain the mean volume delivered(in mL). 7.2 Accuracy Calculate the error (A) of the handpipette, expressed as a percentage, from the equation: where Compare this value with the manufacturers published information. 7.3 Standard deviation Calculate the standard deviation (S)
36、 of the volume delivered from the equation: where Compare this value with the manufacturers published information. 7.4 Coefficient of variation Calculate the coefficient of variation (Cv) expressed as a percentage from the equation: where Compare this value with the manufacturers published informati
37、on. NOTEThe above calculations take no account of any expansion or contraction of the materials from which the instrument is made when it is tested at a temperature different from that at which it was calibrated. However, experience has shown that these factors may be ignored for instruments calibra
38、ted at 20 C and tested within the range 16 C to 25 C. x (1) v is the nominal volume of the handpipette (in mL); is the mean volume delivered by the handpipette (see 7.1.3) (in mL). (2) x is the individual sample measurement (in mL); is the mean volume delivered by the handpipette (in mL) (see 7.1.3)
39、; n is the total number of measurements taken (10 on the procedure above). S is the standard deviation determined in 7.3; is the mean volume delivered by the handpipette (in mL) (see 7.1.3). x x C v 100S x -= x Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrol
40、led Copy, (c) BSI BS 6018:1991 BSI 07-19993 8 Test report The test report shall include the following: a) identification of the pipette; b) the method of test, e.g. “In accordance with BS 6018”, and the date of test; c) the nominal volume at which the test was carried out (see clause 6); d) the mean
41、 temperature at which the test was carried out; e) the accuracy (see 7.2); f) the standard deviation (see 7.3); g) the coefficient of variation (see 7.4). Table 1 Variation of the apparent density in air of distilled or deionized water with temperature TemperatureDensityTemperatureDensity C 16 17 18
42、 19 20 g/mL 0.99789 0.99772 0.99754 0.99735 0.99715 C 21 22 23 24 25 g/mL 0.99694 0.99672 0.99649 0.99624 0.99599 NOTEThese density values take account of the conventional values of the result of weighing in air in International Recommendation No. 33 (IR 33) published by the International Organizati
43、on of Legal Metrology (OIML). Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 BSI 07-1999 Publication(s) referred
44、 to BS 593, Specification for laboratory thermometers. BS 3978, Specification for water for laboratory use. BS 7532, Method of test for accuracy and precision of mechanical handpipettes of capacity less than 50 L down to and including 10 L. International Recommendation No. 33, International Organiza
45、tion of Legal Metrology, London 19792). 2) Available from Technology Reports Centre, Department of Trade and Industry, Station Square House, St Mary Cray, Orpington, Kent. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:36:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6018:1991 BSI 389
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