1、Designation: E672 87 (Reapproved 2011)Standard Specification forDisposable Glass Micropipets1This standard is issued under the fixed designation E672; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This specification covers two different types of dispos-a
3、ble micropipets, calibrated “to contain,” used in measuringmicrolitre volumes of liquids.1.2 The values stated in SI units are to be regarded as thestandard.1.3 The following precautionary caveat pertains only toparagraph 9.1.1 of this specification. This standard does notpurport to address all of t
4、he safety concerns, if any, associatedwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory limitations prior touse.2. Referenced Documents2.1 ASTM Standards:2E438 Specification for Glasses
5、 in Laboratory Apparatus2.2 ISO Standard:3R-1769 Color Coding for Pipets3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 accuracythe closeness of agreement between thenominal value and the mean volume, obtained by applying thetest procedure specified in 9.4.1. It is quantified
6、by theinaccuracy of the mean (bias).3.1.2 disposable micropipetsuch micropipets will only beexpected to provide their specified performance during theiroriginal use or operation.NOTE 1The descriptions of “accuracy” and “repeatability” apply onlyin cases where the distributions are Gaussian.3.1.3 rep
7、eatabilitythe closeness of agreement between theindividual volumes obtained by applying the test procedurespecified in 9.4.2. It is quantified by the imprecision.4. Classification4.1 This specification covers two different pipet designs asfollows:4.1.1 Type IDisposable micropipets with calibration l
8、ineand color coding (see Fig. 1 and Table 1).4.1.2 Type IIDisposable micropipets void of markings(see Fig. 2 and Table 2).NOTE 2Type I pipets were originally specified by the Department ofDefense under MIL-P-36722.5. Materials and Manufacture5.1 The pipets made to these specifications shall be fabri
9、-cated from borosilicate glass, Type I, Class A or B or soda limeglass, Type II, in accordance with Specification E438.6. Dimensions and Permissible Variations6.1 DesignPipets shall be of one piece construction inaccordance with Table 1 and Table 2 for shape, dimensions,and permissible variations. A
10、ny cross-section of the pipet,taken in a plane perpendicular to the longitudinal axis, shall becircular.6.2 CapacityThe pipet capacity shall be stated on thepackage label, expressed as L(microlitre); this shall be knownas the stated capacity, V1, in making subsequent calculations.The expected deviat
11、ion from the stated capacity shall beexpressed as accuracy and coefficient of variation and shall betested for capacity as specified in 9.1. The unit, microlitre, L,may be considered as equivalent to 0.001 cm3.1This specification is under the jurisdiction of ASTM Committee E41 onLaboratory Apparatus
12、 and is the direct responsibility of Subcommittee E41.01 onApparatus.Current edition approved Dec. 1, 2011. Published December 2011. Originallyapproved in 1978. Last previous edition approved in 2006 as E672 87 (2006).DOI: 10.1520/E0672-87R11.2For referenced ASTM standards, visit the ASTM website, w
13、ww.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.
14、ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2.1 Accuracy (see 4.1)The accuracy shall be determinedas specified in 9.4 and shall be within the limits given in Table1 and Table 2.6.2.2 Coeffcient of Variation (see sectio
15、n 4.2)The coeffi-cient of variation shall be determined as specified in 9.4 andshall be within the limits given in Table 1 and Table 2.6.3 Capacity MarkPipets in Fig. 1 shall have a capacityline that is calibrated “to contain” a volume of liquid at 20C.The capacity line shall be 0.3 to 0.5 mm wide a
16、nd shallcompletely encircle the pipet in a plane perpendicular to itslongitudinal axis.6.4 Identification Markings:6.4.1 Type IThe pipets in Fig. 1 shall be identified forcapacity by a color code marking on each pipet consisting ofone or two color bands (see Table 1). For a code consisting ofone ban
17、d, the band shall be from 2 to 6 mm wide; for a codeconsisting of two bands, each band shall be 2 to 6 mm wide andseparated with a space of 2 to 6 mm. The color code band, orbands, shall completely encircle the pipet in a plane perpen-dicular to its longitudinal axis. The location of color band, orF
18、IG. 1 Type I PipetTABLE 1 Dimensions for Type I PipetStated Capacity,LColor CodeMinimum Di-ameter A, mmMinimum WallB, mmMaximum Volumetric DeviationAccuracy, %Coefficient ofVariation, %5 white 1.0 0.35 61.0 1.510 orange 1.0 0.25 60.5 1.020 black 1.1 0.25 60.5 1.025 2 white 1.1 0.25 60.5 1.050 green
19、1.3 0.20 60.5 1.0100 blue 1.6 0.20 60.5 1.0200 red 2.2 0.20 60.5 1.0FIG.2TypeIIPipetE672 87 (2011)2bands, shall be as specified in Fig. 1 with the selection of color,to designate capacity, according to ISO RecommendationR-1769.6.4.2 Type IIPipets in Fig. 2 are devoid of any markingsand shall be iden
20、tified for capacity on the package label.7. Workmanship, Finish and Appearance7.1 The pipets in Fig. 1 and Fig. 2 shall be free of defectsthat will detract from their appearance or may impair theirserviceability. The pipets shall be free of significant foreignmatter, loose or embedded lint or chips
21、that affect the bore, orstains when viewed under normal room lighting.7.2 The calibration line and color code on Type I pipets shallbe applied to the glass pipet at locations specified in Fig. 1. Thecalibration line shall be sufficiently deposited on the glass toenable the setting of a meniscus and
22、the color band shall besufficiently deposited on the glass to identify the pipet as to itsstated volume.8. Reading and Setting the Meniscus8.1 Reading a Liquid Meniscus (Type I only)For allpipets, the reading is made on the lowest point of the meniscus.In order that the lowest point may be observed,
23、 it is necessaryto place a shade of some dark material immediately below andbehind the meniscus, which renders the profile of the meniscusdark and clearly visible against a light background.8.1.1 Setting a Liquid MeniscusSetting of the meniscusshall be performed by one of the following methods. Wher
24、everpractical, the meniscus should descend to the position ofsetting.8.1.1.1 Method AThe position of the lowest point of themeniscus with reference to the graduation line is horizontallytangent to the plane of the upper edge of the graduation line.The position of the meniscus is obtained by having t
25、he eye inthe same plane of the upper edge of the graduation line.8.1.1.2 Method BThe position of the lowest point of themeniscus with reference to the graduation line is such that it isin the plane of the middle of the graduation line. This positionof the meniscus is obtained by making the setting i
26、n the centerof the ellipse formed by the graduation line on the front and theback of the tube as observed by having the eye slightly belowthe plane of the graduation line. The setting is accurate if, asthe eye is raised and the ellipse narrows, the lowest point of themeniscus remains midway between
27、the front and rear portionsof the graduation line. By this method it is possible to observethe approach of the meniscus from either above or below theline to its proper setting.8.2 Reading a Mercury Meniscus (Type I only)For allpipets, the reading is made at the highest point of the meniscus.In orde
28、r that the highest point may be observed, it is necessaryto place a shade of some light material immediately above andbehind the meniscus, which renders the profile of the meniscusdark and clearly visible against a light background.8.2.1 Setting a Mercury MeniscusSetting of the meniscusshall be perf
29、ormed by one of the following methods. Whereverpractical, the meniscus should descend to the position ofsetting.8.2.1.1 Method AThe position of the highest point of themeniscus with reference to the graduation line is horizontallytangent to the plane of the lower edge of the graduation line.The posi
30、tion of the meniscus is obtained by having the eye inthe same plane of the lower edge of the graduation line.8.2.1.2 Method BThe position of the highest point of themeniscus with reference to the graduation line is such that it isin the plane of the middle of the graduation line. This positionof the
31、 meniscus is obtained by making the setting in the centerof the ellipse formed by the graduation line on the front and theback of the tube as observed by having the eye slightly abovethe plane of the graduation line. The setting is accurate if, asthe eye is lowered and the ellipse narrows, the highe
32、st point ofthe meniscus remains midway between the front and rearportions of the graduation line. By this method it is possible toobserve the approach of the meniscus from either above orbelow the line to its proper setting.NOTE 3The difference between meniscus positions resulting from thealternativ
33、e methods of adjustment is the volume equivalent of one half thethickness of the graduation line. When working to the highest attainableaccuracy, the difference between the two methods of adjustment isunlikely to exceed 0.4 % volumetric error from stated capacity and acorrection can be calculated wh
34、ere necessary.9. Testing9.1 Capacity (Single Pipet):9.1.1 Type I (Using Mercury)Allow a dry pipet and acontainer of triple distilled mercury to stand at room tempera-ture of 20 to 25C for 2 h. Fill the pipet with mercury andadjust to the calibration line in accordance with 8.2 and 8.2.1.Discharge th
35、e mercury in the pipet into a clean tared dish, andreweigh the dish, together with the mercury content. Recordthe room temperature. From the recorded weight of theTABLE 2 Dimensions for Type II PipetStated Capacity,LMinimumLength A, mmMinimum Di-ameter B, mmMinimum WallC, mmMaximum Volumetric Deviat
36、ionAccuracy, %Coefficient ofVariation, %1 20 0.5 0.20 61.5 2.02 20 0.5 0.20 61.2 1.53 20 0.6 0.20 61.2 1.54 20 0.6 0.20 61.2 1.55 20 0.6 0.20 61.2 1.510 20 0.6 0.10 61.0 1.220 20 0.6 0.10 61.0 1.225 30 0.6 0.10 61.0 1.250 30 1.0 0.10 61.0 1.2100 50 1.3 0.10 61.0 1.2E672 87 (2011)3mercury discharged
37、into the dish and the recorded temperature,calculate the volume of mercury (representing the observedcapacity of the pipet) in accordance with 9.2 and Table X1.1.9.1.2 Type I (Using Water)Allow a dry pipet and acontainer of distilled water to stand at room temperature of 20to 25C for 2 h. Weigh the
38、dry pipet and record the weight. Fillthe same pipet with water and adjust to the calibration line inaccordance with 8.1 and 8.1.1. Then reweigh the pipet withwater content and record the weight. Record the room tem-perature. Subtract the recorded weight of the dry pipet from therecorded weight of th
39、e pipet filled with distilled water repre-senting the apparent mass of the contained water. Calculate thevolume, V, in accordance with 9.2 and Appendix X2.9.1.3 Type IIAllow a dry pipet and a container of distilledwater to stand at room temperature 20 to 25C for 2 h. Weighthe dry pipet and record th
40、e weight. Then fill the same pipetwith distilled water, by capillary attraction with specific care toremove all water from the exterior of the pipet with a dry clothor gauze. Then reweigh the pipet with water content, andrecord the weight. Record the room temperature. Subtract therecorded weight of
41、the dry pipet from the recorded weight ofthe pipet filled with distilled water representing the apparentmass of the contained water. Calculate the volume, V,inaccordance with 9.2 and Table X1.2.NOTE 4To accurately perform the test methods outlined in 9.1.1,9.1.2, and 9.1.3, the reliability of the we
42、ighing instrument used should beconfirmed against a known standard and the weighing instrument shouldpossess a minimum sensitivity that does not exceed the following:Stated Capacity Minimum Sensitivity1to5L 0.001mg10 to 200 L 0.01 mg9.2 CalculationsCalculate the volume, V, of a micropipetfrom the we
43、ighings, in air, using the following equation:V 5 W3 Z (1)where:W = apparent mass of liquid (mercury/water), weighed inair, andZ = apparent specific volume, (mercury/water).Values of Z for mercury and water are given in AppendixesX1 and X2, respectively.9.3 Capacity Deviation (Single Pipet)In accord
44、ance withthe methods outlined in 9.1.1, 9.1.2, and 9.1.3, using eithermercury or water, the capacity deviation is the differencebetween the stated capacity and the observed capacity of thepipet as follows:Capacity Deviation, % 5Vc2 V1! 3 100V1(2)Vc5Vt1 1 at 2 20C!where:Vt= observed volumetric capaci
45、ty at tC, L,Vc= corrected volumetric capacity at 20C,a = coefficient of cubical expansion of pipet glass;0.000010/C for Type I, Class A borosilicate;0.000015/C for Type I, Class B (noncorrosive boro-silicate); and 0.000025/C for Type II, (sodalime).V1= stated capacity of pipet, andt = temperature, C
46、.9.4 Capacity Deviation (Number of Pipets)Test a mini-mum of 30 Type I or Type II pipets, or both, taken at randomfrom a completed manufactured production lot, in accordancewith 9.1.1, 9.1.2,or9.1.3. Calculate the volumetric deviationfor the 30 pipets as follows:9.4.1 Accuracy:Accuracy, % 5100 x 2 V
47、1!V1(3)where:x = mean of sample measurements, andV1= stated capacity of pipet.9.4.2 Coeffcient of Variation:Coefficient of Variation, % 5100sx(4)s 5(x 2 x!2n 2 1where:x = individual sample measurement,x = mean of sample measurements, andn = number of pipets measured.10. Keywords10.1 disposable; glas
48、s; micropipetsE672 87 (2011)4APPENDIX(Nonmandatory Information)X1. Density and Z Factor TablesASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determinat
49、ion of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
