ASTM E2603-08

Standard Practice for Calibration of Fixed-Cell Differential Scanning Calorimeters

SIGNIFICANCE AND USE
Fixed-cell differential scanning calorimeters are used to determine the transition temperatures and energetics of materials in solution. For this information to be accepted with confidence in an absolute sense, temperature and heat calibration of the apparatus or comparison of the resulting data to that of known standard materials is required.  
This practice is useful in calibrating the temperature and heat flow axes of fixed-cell differential scanning calorimeters.
SCOPE
1.1 1.1 This practice covers the calibration of fixed-cell differential scanning calorimeters over the temperature range from –10 to +120°C.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7.

General Information

• Status: Historical
• Publication Date: 31-Aug-2008
• ICS: 17.200.10 - Heat. Calorimetry
• Technical Committee: E37 - Thermal Measurements
• Drafting Committee: E37.09 - Microcalorimetry

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2603 − 08
StandardPractice for
Calibration of Fixed-Cell Differential Scanning Calorimeters
This standard is issued under the fixed designation E2603; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope perature scan rate capabilities, provision for electrical calibra-
tion of heat flow, and a smaller range of temperature over
1.1 This practice covers the calibration of fixed-cell differ-
which they operate. The larger sample cells, and their lack of
ential scanning calorimeters over the temperature range from
disposability, make inapplicable the calibration methods of
–10 to +120°C.
Practices E967 and E968.
1.2 The values stated in SI units are to be regarded as
4.2 This practice consists of heating the calibration mate-
standard. No other units of measurement are included in this
rialsinaqueoussolutionatacontrolledratethrougharegionof
standard.
known thermal transition. The difference in heat flow between
1.3 This standard does not purport to address all of the
the calibration material and a reference material, both relative
safety concerns, if any, associated with its use. It is the
to a heat reservoir, is monitored and continuously recorded. A
responsibility of the user of this standard to establish appro-
transition is marked by the absorption or release of energy by
priate safety and health practices and determine the applica-
the specimen resulting in a corresponding peak in the resulting
bility of regulatory limitations prior to use. Specific precau-
curve.
tionary statements are given in Section 7.
4.3 The fixed-cell calorimeters typically, if not always, have
2. Referenced Documents electrical heating facilities for calibration of the heat-flow axis.
Despitetheuseofresistanceheatingforcalibration,achemical
2.1 ASTM Standards:
calibration serves to verify the correct operation of the calibra-
E473 Terminology Relating to Thermal Analysis and Rhe-
tion mechanism and the calorimeter. The thermal denaturation
ology
of chicken egg white lysozyme is used in this practice for
E967 Test Method for Temperature Calibration of Differen-
verification of the proper functioning of the instrument’s
tial Scanning Calorimeters and Differential Thermal Ana-
systems.The accuracy with which the denaturation enthalpy of
lyzers
chicken egg white lysozyme is currently known, 65%, is such
E968 Practice for Heat Flow Calibration of Differential
thatitshouldberarethatacalorimeterprovidesavalueoutside
Scanning Calorimeters
that established in the literature for this reference material.
E1142 Terminology Relating to Thermophysical Properties
5. Significance and Use
3. Terminology
5.1 Fixed-cell differential scanning calorimeters are used to
3.1 Specific technical terms used in this practice are defined
determine the transition temperatures and energetics of mate-
in Terminologies E473 and E1142.
rials in solution. For this information to be accepted with
confidence in an absolute sense, temperature and heat calibra-
4. Summary of Practice
tion of the apparatus or comparison of the resulting data to that
4.1 This practice covers calibration of fixed-cell differential
of known standard materials is required.
scanning calorimeters. These calorimeters differ from another
5.2 This practice is useful in calibrating the temperature and
category of differential scanning calorimeter in that the former
heat flow axes of fixed-cell differential scanning calorimeters.
have generally larger sample volumes, slower maximum tem-
6. Apparatus
This practice is under the jurisdiction of ASTM Committee E37 on Thermal
6.1 Apparatus shall be:
Measurements and is the direct responsibility of Subcommittee E37.09 on Biologi-
6.1.1 Differential Scanning Calorimeter (DSC), capable of
cal Calorimetry.
heating a test specimen and a reference material at a controlled
Current edition approved Sept. 1, 2008. Published October 2008. DOI: 10.1520/
E2603-08.
rate and of automatically recording the differential heat flow
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
between the sample and the reference material to the required
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
sensitivity and precision.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.1.2 DSC Test Chamber, composed of:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2603 − 08
TABLE 1 Melting Temperature of Calibration Material
6.1.2.1 Adevice(s) to provide uniform controlled heating or
cooling of a specimen and reference to a constant temperature
NOTE 1—The uncertainties for the temperatures are ±0.1 K.
or at a constant rate within the applicable temperature range of
Melting Tempera-
this method.
Calibration Material ture
°C K
6.1.2.2 Atemperature sensor to provide an indication of the
1,2-ditridecanoyl-sn-glycero-3-phosphocholine (DTPC) 13.25 286.4
specimen temperature to 60.01 K.
1,2-ditetradecanoyl-sn-glycero-3-phosphocholine (DMPC) 23.75 296.9
6.1.2.3 Differential sensors to detect a heat flow (power)
1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC) 41.45 314.6
1,2-dioctadecanoyl-sn-glycero-3-phosphocholine (DSPC) 54.85 328.0
difference between the specimen and reference with a sensi-
1,2-dieicosanoyl-sn-glycero-3-phosphocholine (DAPC) 65.05 338.2
tivity of 60.1 µW.
1,2-didocosanoyl-sn-glycero-3-phosphocholine (DBPC) 73.35 346.5
6.1.3 A temperature controller, capable of executing a 1,2-ditetracosanoyl-sn-glycero-3-phosphocholine (DLPC) 80.55 353.7
specific temperature program by operating the furnace(s)
between selected temperature limits at a rate of temperature
change of 0.01 K/min to 1 K/min constant to 60.001 K/min or
The solutions are heated in a hot water bath to 5 K above the
at an isothermal temperature constant to 60.001 K.
transition temperatures. A vortex mixer is used to shake the
6.1.4 A data collection device, to provide a means of
solutionsattheirrespectivetemperaturesuntilthelipidappears
acquiring, storing, and displaying measured or calculated
to have been completely suspended. The solutions may be
signals,orboth.TheminimumoutputsignalsrequiredforDSC
stored in a refrigerator until use for up to a week.
are heat flow, temperature, and time.
6.1.5 Containers, that are inert to the specimen and refer-
8.2 Chicken egg white lysozyme with purity of at least 95%
ence materials and that are of suitable structural shape and
mass percent.
integrity to contain the specimen and reference in accordance
8.2.1 Weighed amounts of the lysozyme and of a 0.1 M HCl
with the specific requirements of this test method. These
– glycine buffer at pH = (2.4 6 0.1) are combined to obtain a
containers are not designed as consumables.They are either an
solution of approximately 3 mass percent.
integral part of the instrument, whether or not user-removable
8.2.2 The concentration of lysozyme in this solution is
for replacement or, in some implementations, are removable
calculated from UV absorbance at a wavelength of 280 nm,
and reusable. Container volumes generally range from 0.1 ml
usinga1cm cell and the optical density of 2.65 fora1mg
-1
to 1 ml, depending on the instrument’s manufacture.
mL solution.
8.2.2.1 Fill a 1 cm optical cell with buffer solution and
6.2 Analytical Balance, capable of weighing to the nearest
another 1 cm cell with the lysozyme solution. Follow the
0.1 mg, for preparation of solutions.
instrument’s directions for establishing baseline, and if needed,
6.3 UV spectrophotometer or UV/Vis spectrophotometer,
calibration of the absorbance scale. Insert both of the filled
capableofscanningtheUVspectruminaregionabout280nm.
cells in the UVspectrometer if the spectrometer is a dual beam
6.4 Reagents:
instrument. Scan through the 280 nm region and note the
6.4.1 Phosphatidylcholines, 1,2-ditridecanoyl-sn-glycero-3- absorbance at 280 nm. If the spectrometer is a single beam
phosphocholine (DTPC) CAS Number 71242-28-9 and 1,2- instrument, the buffer is measured first, then the lysozyme
ditetracosanoyl-sn-glycero-3-phosphocholine (DLPC) CAS
solution is measured and the difference in the recorded absor-
Number 91742-11-9 are the minimum required. bances is used to calculate the concentration. Concentration is
6.4.2 Aqueous buffer solutions, 0.01 Molar, pH 7 aqueous
calculated as:
solution of Na2HPO4 – NaH2PO4 and 0.1 Molar, pH (2.4 6
c 5 A/ 2.65mLmg
~ !
0.1) aqueous solution of HCl + glycine.
where:
6.4.3 Chicken egg white lysozyme.
A = absorbance, and
7. Precautions -1.
c = concentration in mg mL
7.1 This practice assumes linear temperature indication. NOTE 1—Different concentrations may be used between 1 and 10 mass
percent, the concentration used shall be included in the report.
Care must be taken in the application of this practice to ensure
that calibration points are taken sufficiently close together so
9. Procedure
that linear temperature indication may be approximated.
9.1 Two Point Temperature Calibration:
8. Calibration Materials
9.1.1 Determine the apparent transition temperature for
8.1 Phosphatidylcholines: 1,2-ditridecanoyl-sn-glycero-3- each calibration material, as described in Table 1.
phosphocholine (DTPC) CAS Number 71242-28-9; and 1,2- 9.1.1.1 Fill the clean specimen cell with the phosphatidyl-
ditetracosanoyl-sn-glycero-3-phosphocholine (DLPC) CAS cholinesuspension,accordingtotheusualmethodspecifiedfor
Number 91742-11-9. Purities are to be 0.99 or better. Addi- the instrument. Fill the reference cell with buffer solution that
tional calibration materials are listed in Table 1. was used to prepare the phosphatidylcholine suspension.
8.1.1 Aqueous suspensions of the phosphatidylcholines are 9.1.1.2 Equilibrate the calorimeter approximately 10 K to
prepared as follows. Weighed amounts of a 0.01 Molar, pH 7 15 K below the expected transition temperature from Table 1.
solution of the buffer Na HPO – NaH2PO and DTPC are 9.1.1.3 Heat each calibration material at the desired scan
2 4 4
combined so to give a solution of 1 mass p
...