1、Designation: E 2402 05Standard Test Method forMass Loss and Residue Measurement Validation ofThermogravimetric Analyzers1This standard is issued under the fixed designation E 2402; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method provides procedures for validating massloss and residue measurements by thermogravimetric analy
3、zers(TGA) and analytical methods based upon the measurement ofmass loss or residue content. Performance parameters deter-mined include mass loss and residue repeatability (precision),detection limit, quantitation limit, linearity and bias.1.2 Validation of apparatus performance and analyticalmethods
4、 is requested or required for quality initiatives or whereresults may be used for legal purposes.1.3 SI units are the standard.1.4 There is no ISO standard equivalent to this method.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theres
5、ponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 473 Terminolog
6、y Relating to Thermal AnalysisE 1142 Terminology Relating to Thermophysical PropertiesE 1582 Practice for Calibration of Temperature Scale forThermogravimetryE 1970 Practice for Statistical Treatment of Thermoanalyti-cal DataE 2040 Method for Mass Scale Calibration of Thermogravi-metric AnalyzersE 2
7、161 Terminology Relating to Performance Validation inThermal Analysis2.2 Other Standard:United States Food and Drug Administration, Q2B Valida-tion of Analytical Procedures: Methodology, 62 FR27464, May 19, 199733. Terminology3.1 Technical terms used in this standard are defined inPractice E 177 and
8、 in Terminologies E 473, E 1142, andE 2161.3.2 Definitions of Terms Specific to This Standard:3.2.1 highly volatile mattermaterials (such as moisture,plasticizer, residual solvent, etc.) that boil at temperaturesbelow 200 C.3.2.2 medium volatile mattermaterials (such as oil andpolymer degradation pr
9、oducts) that boil in the temperaturerange between 200 and 400 C.3.2.3 residuematerial remaining (such as metal compo-nents, filler content or inert reinforcing materials) after morevolatile components are vaporized.3.2.4 mass loss plateaua region of a thermogravimetriccurve with a relatively constan
10、t mass (that is, accompanied bya minima in the first derivative of mass with respect to time).4. Summary of Test Method4.1 Mass is the primary dependent parameter and tempera-ture is the primary independent parameter measured by TGA.4.2 Mass loss and residue measurements are validated bytheir direct
11、 measurement using thermogravimetric apparatusover a specified temperature range using reference materials ofknown volatiles content as an analyte.4.3 Alternatively, validation of a TGA method based uponmass loss and residue measurements may be performed usinga specific test specimen as the analyte.
12、4.4 The mass loss of three or more specimens (nominallyrepresenting the maximum, midpoint and minimum of therange of the test method) is measured at least in triplicate. Afourth blank specimen, containing no analyte, is also measuredat least in triplicate.NOTE 1Repeatability is determined by perform
13、ing a sufficient num-ber of determinations to calculate statistically valid estimates of the1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on ThermalAnalysis and Rheology Methods.Current edition approved
14、 Jan. 1, 2005. Published February 2005.2For referenced ASTM standards, visit the ASTM website, www.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 FDA, 5
15、600 Fishers Lane, Rockville, MD 20857.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.standard deviation or relative standard deviation of the measurements.4.4.1 Mass loss and residue linearity and bias are deter-mined from the best-
16、fit straight-line correlation of the resultsfrom measurements of the three or more specimens.4.4.2 Mass loss and residue detection limit and quantitationlimit are determined from the standard deviation of the blankspecimen measurements.4.4.3 Mass loss and residue repeatability are determinedfrom the
17、 repeatability measurements of the three or moreanalyte-containing specimens.5. Significance and Use5.1 This method may be used to validate the performance ofa specific TGA apparatus.5.2 This method may be used to validate the performance ofa specific method based upon a TGA mass loss or residuemeas
18、urement.5.3 This method may be used to determine the repeatabilityof a specific apparatus, operator or laboratory.5.4 This method may be used for specification and regula-tory compliance purposes.6. Interferences6.1 This method depends upon distinctive thermal stabilityranges of the measured compone
19、nts as a principle of the test.For this reason, impurities or other materials that have nowell-defined thermally stable range, or the thermal stability ofwhich are the same as other components, may create interfer-ences.7. Apparatus7.1 Thermogravimetric Analyzer (TGA)The essential in-strumentation r
20、equired to provide minimum thermogravimetrycapability for this method includes:7.1.1 A thermobalance composed of:7.1.1.1 A furnace to provide uniform controlled heating of aspecimen to a constant temperature of 400 C and at a constantrate between 5 and 25 C/min.7.1.1.2 A temperature sensor to provid
21、e an indication of thespecimen/furnace temperature to 6 0.1 C.7.1.1.3 A continuous recording balance with a minimumcapacity of 100 mg and a sensitivity of 6 10 g to measure thespecimen mass.7.1.1.4 A means of maintaining the specimen/containerunder a controlled atmosphere using an inert gas of 99.9+
22、 %purity at a purge rate of 50 to 100 6 5 mL/min.NOTE 2Excessive purge rates should be avoided as they may intro-duce interferences due to turbulence effects and temperature gradients.7.1.2 A temperature controller capable of executing a spe-cific temperature program by operating the furnace between
23、selected temperature limits at a rate of temperature change of5 to 25 C/min to within 6 0.5 C/min.7.1.3 A recording device capable of recording and display-ing any fraction of the specimen mass signal (TGA curve)including the signal noise as a function of any fraction oftemperature including noise.7
24、.1.4 Containers (pans, crucibles, etc.) that are inert to thespecimen and that will remain gravimetrically stable up to450 C.7.2 Graduated micropipettes with a capacity of 20 to 40 Lmeasurable to within 6 1 L.8. Reagents and Materials8.1 Mass Loss Reference Materials, preferably certified formass lo
25、ss covering a range of 2, 50, and 98 % mass loss overthe temperature range of 25 to 200 C.NOTE 3Materials with other mass loss values may be used but shallbe reported.8.2 Nitrogen (or other inert purge gas) of 99.9+ % purity.9. Hazards9.1 During the course of these experiments, organic vaporsare evo
26、lved from the specimen and will exhaust from theinstrument.Aventilation system shall be used to ensure that theoperator is not exposed to these vapors.9.2 Review the Material Safety Data Sheets (MSDS) for thecomponents of the Mass Loss Reference Materials for addi-tional safety information.10. Calib
27、ration and Standardization10.1 After turning the power on, allow the instrument toequilibrate for at least one hour prior to any measurement.10.2 Perform any cleaning and calibration procedures de-scribed by the manufacturer in the apparatus OperatorsManual.10.3 If not previously established, perfor
28、m temperature andmass calibrations according to Practices E 1582 and E 2040,respectively, using the same purge gas, purge flow rate andheating rate (here 10 C/min) to be used for validation experi-ments.11. Procedure for Determining Mass Loss and ResidueMeasurement Repeatability, Detection Limit,Qua
29、ntitation Limit, Linearity and Bias11.1 This process involves characterizing, in triplicate,specimens with no mass loss and at least three or more testspecimens taken to represent the low, medium and highextremes of the range over which performance is to bevalidated.NOTE 4The details of this procedu
30、re are written using mass lossreference materials as an analyte, and with a generic set of experimentalconditions. For validation of a specific mass loss method, specimens of theanalyte should be prepared to represent the range of the intended testmethod, and steps 11.2 to 11.20 replaced with the sp
31、ecific mass lossprocedure (that is, sample size, heating rate, purge gas, purge flow rate,etc.).11.2 Prepare at least 150 mg quantities of each of thereference specimens covering the mass loss range of the test.Nominal mass values might be 2, 50, and 98 mass loss %.NOTE 5Most thermoanalytical method
32、s cover 1.5 to 2 decades ofrange. The mass values selected should approximate the anticipated range.Other masses losses and mass ranges may be used but shall be reported.11.3 Tare the empty sample pan.E240205211.4 Using a micropipette, load 20 to 40 L 6 1Loflargest mass loss specimen (for example, t
33、he 98 mass loss %reference material) onto the sample container. Close theapparatus in preparation for conducting the experiment. Weighand record the test specimen mass as Mo(1). Purge the samplechamber with dry nitrogen (or other inert gas) at a flow rate of50 to 100 mL/min 6 10 % throughout the exp
34、eriment.NOTE 6Other specimen volumes may be used but shall be reported.11.5 Heat the test specimen at 10 C/min from 25 to 400 Cand record the thermal curve.NOTE 7Other heating rates may be used but shall be reported. Higherrates, however, may reduce the resolution between high volatility andmedium v
35、olatility component leading to poorer detection and quantitationlimits.11.6 Cool the test specimen to 25 C. The thermal curveneed not be recorded.11.7 Select a point on the mass loss thermal curve from 11.5before and another on the mass loss plateau immediately afterthe first mass loss. These temper
36、ature points are identified at T1and T2, respectively. Record the masses at these two points asM1(1) and M2(1) (see Fig. 1).NOTE 8The valley of the first derivative curve may be useful inidentifying T2the point of maximum resolution between the lower (highvolatility) and higher temperature (medium v
37、olatility) mass loss regions.NOTE 9It is common to select T1to be ambient temperature andM1(1) to be Mo(1)11.8 Determine the mass loss between M1(1) and M2(1) asmass loss DMmax(1) according to Eq 2.11.9 Repeat steps 11.3 through 11.8 for the medium massloss test specimen from step 11.2. Use the same
38、 measurementlimits (T1and T2) determined in step 11.7. Record this massloss DMmid(1).11.10 Repeat steps 11.3 through 11.8 for the low mass losstest specimen from step 11.2 Use the same measurement limits(T1and T2) determined in step 11.7. Record the mass lossDMmin(1).11.11 Repeat steps 11.3 through
39、11.8 for an empty containerin which no test specimen is used. This is the blank determi-nation. Use the same measurement limits (T1and T2) deter-mined in step 11.7 (Fig. 2). Record the mass remaining (Mr(1)in mg.NOTE 10Observe and record the sign of the value for Mr. It may bepositive (apparent weig
40、ht gain) or negative (apparent mass loss).11.12 Repeat steps 11.3 through 11.8 two more times for thelarge mass loss specimen. Record these values as mass lossesDMmax(2) and DMmax(3).11.13 Repeat steps 11.3 through 11.8 two more times for themedium mass loss specimen. Record these values as massloss
41、es DMmid(2) and DMmid(3).11.14 Repeat steps 11.3 through 11.8 two more times for thelow mass loss specimen. Record these values as mass lossesDMmin(2) and DMmin(3).11.15 Repeat steps 11.3 through 11.7 two more times for theblank (no test specimen) case. Record these values as residueMr(2) and Mr(3).
42、11.16 Calculate the means (Mrand DM), and standarddeviations (s) for the mass losses, respectively, from thereplicate determinations made on each of the three blank andFIG. 1 Determination of Mass Loss for Medium Mass Loss MaterialE2402053mass loss specimens (see Practice E 1970). Record thesevalues
43、 as Mr, DMmax, DMmid, DMmin, sr, smax, smid, and smin.11.17 Using the standard deviation for the mass loss of theblank (sr) from 11.16, determine and report the mass loss andresidue detection limit (DL) and quantitation limit (QL) usingEq 3 and Eq 4, respectively.11.18 Calculate the pooled relative
44、standard deviation forthe mass loss from the smax, smid, and sminobtained in 11.16(see Practice E 1970). Report this value as the mass lossrepeatability value (r) in mass %.11.19 Using the known mass loss values from step 11.2 asthe independent (X) values and the mean values for mass lossfrom step 1
45、1.16 as the dependent (Y) values, determine theleast squares best-fit values for the slope (m) and intercept (b)(see Practice E 1970).11.20 Calculate the linearity (L) from the values in 11.19using Eq 5.11.21 Report the measurement bias as M, in mg. Themeasurement bias may be expressed as mass % for
46、 comparisonpurposes to the other validation parameters using Eq 6.12. Calculation12.1 When performing these calculations, retain all avail-able decimal places in the measured values and in intermediatecalculated values. The final result should be rounded to threesignificant figures.12.2 Residue is c
47、alculated by Eq 1.R 5 M23 100%/Mo(1)where:R = residue, mass %,M2= mass at the higher temperature, mg, andMo= mass at the beginning of the experiment, mg.12.3 Mass loss is calculated using Eq 2.DM 5 M12 M2! 3 100%/Mo(2)where:DM = mass loss, mass %, andM1= mass at the lower temperature, mg.12.4 Mass l
48、oss detection limit is calculated using Eq 3.DL 5 3.3 sr(3)where:DL = mass loss detection limit, mg, andsr= blank mass loss standard deviation, mg,12.5 Mass loss quantitation limit is calculated using Eq 4:QL 5 10 sr(4)where:QL = mass loss quantitation limit, mg.12.6 Linearity is calculated using Eq
49、 5.L 5F? largest dY ?m 3 Xmax1 bG100 % (5)where:L = linearity, mass %,m = slope, dimensionless, (from 11.19),b = intercept, mass %, (from 11.19),Mo= original mass of the sample, mg, and|largest dY| = absolute value of the largest deviation fromthe best-fit straight line.12.7 Bias (Bias) for the residue and mass loss measurementsare equal in magnitude but are opposite in sign. Bias, Mr,isFIG. 2 Blank Determination of ResidueE2402054measured in mg. Bias may be calculated in %, relative to theinitial mass loss, using Eq 6.Bias mass loss!
