ASTM E2977-14
(Practice)Standard Practice for Measuring and Reporting Performance of Fourier-Transform Nuclear Magnetic Resonance (FT-NMR) Spectrometers for Liquid Samples
Standard Practice for Measuring and Reporting Performance of Fourier-Transform Nuclear Magnetic Resonance (FT-NMR) Spectrometers for Liquid Samples
SIGNIFICANCE AND USE
4.1 This practice permits an analyst to compare the performance of an NMR spectrometer for a particular test on any given day with the instrument's prior performance for that test. The practice can also provide sufficient quantitative performance information for problem diagnosis and solving. If complete information about how a test is carried out is supplied and sufficient replicates are collected to substantiate statistical relevance, the tests in this practice can be used to establish the setting and meeting of relevant performance specifications. This practice is not necessarily meant for the comparison of different instruments with each other, even if the instruments are of the same type and model. This practice is not meant for the comparison of the performance of different instruments operated under conditions differing from those specified for a particular test.
SCOPE
1.1 This practice covers procedures for measuring and reporting the performance of Fourier-transform nuclear magnetic resonance spectrometers (FT-NMRs) using liquid samples.
1.2 This practice is not directly applicable to FT-NMR spectrometers outfitted to measure gaseous, anisotropically structured liquid, semi-solid, or solid samples; those set up to work with flowing sample streams; or those used to make hyperpolarization measurements.
1.3 This practice was expressly developed for FT-NMR spectrometers operating with proton resonance frequencies between 200 and 1200 MHz.
1.4 This practice is not directly applicable to continuous wave (scanning) NMR spectrometers.
1.5 This practice is not directly applicable to instruments using single-sideband detection.
1.6 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.7 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.
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Standards Content (Sample)
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Designation: E2977 − 14
StandardPractice for
Measuring and Reporting Performance of Fourier-Transform
Nuclear Magnetic Resonance (FT-NMR) Spectrometers for
Liquid Samples
This standard is issued under the fixed designation E2977; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Resolution Nuclear Magnetic Resonance (NMR) Spec-
troscopy
1.1 This practice covers procedures for measuring and
reporting the performance of Fourier-transform nuclear mag- 2.2 ISO Standard:
netic resonance spectrometers (FT-NMRs) using liquid ISOGuide31ReferenceMaterials—ContentsofCertificates
samples. and Labels
1.2 This practice is not directly applicable to FT-NMR
3. Terminology
spectrometers outfitted to measure gaseous, anisotropically
structured liquid, semi-solid, or solid samples; those set up to
3.1 Definitions—For definitions of terms used in this
work with flowing sample streams; or those used to make practice, refer to Terminology E131, Practice E386, and Refs
hyperpolarization measurements.
(1-4). Chemical shifts are usually given in the dimensionless
quantity, δ, commonly expressed in parts per million. For a
1.3 This practice was expressly developed for FT-NMR
given nucleus, the chemical shift scale is relative and is
spectrometers operating with proton resonance frequencies
commonly pegged to the resonance of an agreed upon refer-
between 200 and 1200 MHz.
ence material as described by Eq 1.
1.4 This practice is not directly applicable to continuous
δ 5 ~ν 2 ν ! ÷ν (1)
sample sample reference reference
wave (scanning) NMR spectrometers.
3.1.1 FrequenciesaregiveninHertz.Becausethenumerator
1.5 This practice is not directly applicable to instruments
is very small compared with the denominator, it is usually
using single-sideband detection.
convenient to express δ in parts per million.
1.6 Units—The values stated in SI units are to be regarded
3.1.2 Asthelocationofaresonanceisdeterminedinpartby
as the standard. No other units of measurement are included in
the ratio of the magnetic field to the radio frequency at which
this standard.
it is observed, chemical shifts and spectral regions are often
1.7 This standard does not purport to address all of the
designated as lower frequency (increased shielding) or higher
safety concerns, if any, associated with its use. It is the
frequency (decreased shielding) relative to a reference point.
responsibility of the user of this standard to establish appro-
Defined in this manner, chemical shifts are independent of
priate safety and health practices and determine the applica-
either the magnetic field or the radio frequency used. Coupling
bility of regulatory limitations prior to use.
constants,whichareindependentofthemagneticfieldorradio
frequency used, are expressed in Hertz.
2. Referenced Documents
3.1.3 nuclear magnetic resonance (NMR) tube camber,
2.1 ASTM Standards: n—maximum total deflection of any part of the outer wall of
E131Terminology Relating to Molecular Spectroscopy the tube held at the ends and rotated 360°; a measure of the
E386Practice for Data Presentation Relating to High- bow in the tube.
3.1.4 NMR tube concentricity, n—maximum variation in
wall thickness of the tube; a measure of how centered the tube
This test method is under the jurisdiction of ASTM Committee E13 on
inside diameter is relative to the tube outer diameter.
Molecular Spectroscopy and Separation Science and is the direct responsibility of
Subcommittee E13.15 on Analytical Data.
Current edition approved Aug. 1, 2014. Published September 2014. DOI:
10.1520/E2977-14.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 4th Floor, New York, NY 10036, http://www.ansi.org.
Standards volume information, refer to the standard’s Document Summary page on Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
the ASTM website. this standard.
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E2977 − 14
4. Significance and Use resonances of impurities observed in the spectrum of the
standard sample should not interfere with the resonances of
4.1 This practice permits an analyst to compare the perfor-
interest in the standard sample. This usually means that the
mance of an NMR spectrometer for a particular test on any
impurity peaks shall not appear within the region of the
givendaywiththeinstrument’spriorperformanceforthattest.
satellite peaks, particularly for resolution standard samples.
The practice can also provide sufficient quantitative perfor-
However, samples with higher water content may still be
mance information for problem diagnosis and solving. If
usable so long as the water signal does not interfere with the
completeinformationabouthowatestiscarriedoutissupplied
spectraltest.WatercontentmaybedeterminedbyKarlFischer
and sufficient replicates are collected to substantiate statistical
titration or by H NMR spectroscopy (protic water only). The
relevance, the tests in this practice can be used to establish the
purity of the analyte(s) shall be stated.
setting and meeting of relevant performance specifications.
5.4.2 Except as noted, the sample solvent should be deuter-
This practice is not necessarily meant for the comparison of
ated to provide a field/frequency lock for the spectrometer, of
different instruments with each other, even if the instruments
the highest purity commonly obtainable, and have an atom-
are of the same type and model. This practice is not meant for
percent deuteration of at least 99%. The solvent’s purity and
the comparison of the performance of different instruments
level of deuteration shall be stated.
operated under conditions differing from those specified for a
5.4.3 When used, chemical shift standards should be of the
particular test.
highest purity commonly available and added to the sample to
achieve a concentration approximately one tenth that of the
5. Test Samples
analyte. The purity and concentration of the chemical shift
5.1 Ingeneral,thetestsamplescalledforinthispracticeare
standard shall be stated.
commercially available materials made explicitly for the test-
5.5 Sample Preparation—Either a m/m method or a v/v
ingofNMRspectrometerperformance.Theparticularsamples
method may be used for sample preparation; however, care
chosen are those that have been widely accepted by the NMR
shall be taken to assure better than 1% accuracy in the
community of users and vendors for these purposes. However,
measurements. If a v/v method is used, the densities used for
in certain instances, especially with higher field instruments,
the liquid components shall be stated. Unless specified
the commonly accepted samples may exhibit characteristics
otherwise, any impurities in the final sample (including water)
that render them less than ideal for such uses.
shouldbelessthan10mol%oftheanalyteconcentration.The
5.2 Each sample shall be uniquely identifiable, and a cer-
final analyte concentration and its uncertainty shall be stated.
tificate containing information about the sample shall be
5.5.1 The sample should be sealed under nitrogen or argon
available (ISO Guide 31). In addition to the information
taking care that the final sample is near atmospheric pressure.
required elsewhere in this practice, the certificate shall list the
5.5.2 Each sample tube shall bear a label stating its content
manufacturer of the sample, the date of manufacture, the name
and reference identifier.
of the sample, and a reference number (for example, sample
5.5.3 For long-term storage, samples should be maintained
serial or lot number) (see Fig. 1).
inthedarktopreventphotolysis.Exceptasnoted,samplesmay
5.3 Sample Tubes—Although sample tubes with sizes rang-
be stored at room temperature. For long-term storage, samples
ing from about 1- to 25-mm outside diameter (OD) are used in
containing chloroform should be kept between −25 and 8°C
modern NMR spectrometers, the 5-mm OD tube remains the
unless the sample is known to have been deoxygenated.
most common size. To avoid detailing test procedures for all
possible tube sizes, this practice specifies tests for use with
6. Preliminary Experimental Procedures
5-mm OD sample tubes. Users requiring sample tubes of
6.1 To achieve consistent results, the following shall be
differing size should scale the quantities, dimensions, and
volumes given here to the requirements of their spectrometers completed before the performance measurement:
taking into account any specific recommendations of the 6.1.1 The sample temperature should be stabilized at ap-
instrument’s manufacturer.
proximately 25°C, controlled during the measurement (8.16),
5.3.1 The inside diameter of the sample container shall be and specified in the report.
stated along with tolerances from the manufacturer.
6.1.2 The magnetic field homogeneity shall be adjusted to
5.3.2 Thequalityofthetubeintermsofitsconcentricityand
the best achievable on the sample to be used (8.9 – 8.12).
camber shall be stated. The concentricity and camber of the
6.1.3 The observe radio frequency (rf) circuitry shall be
tube should be less than 60.025 mm and 60.013 mm,
well-tunedandmatchedtothesampletobeused.Ifdecoupling
respectively.
is used, the decoupling rf circuitry shall be tuned and matched
to the sample to be used.
5.4 Analytes, Solvents, and Chemical Shift Standards—
Analyte concentration is defined as a volume percentage (v/v) 6.1.4 The 90° pulse for the probe to be used should be
at 25°C, that is, the volume of the analyte divided by the total measuredandreported.Ifdecouplingisused,parameters,such
volume of the solution. as peak power in Hertz, mean power level in Hertz, and the
5.4.1 Unless otherwise specified, the chemical purity of decouplingmodulationpatternshallbemeasuredandreported.
each component for standard samples used to test sensitivity ThedecouplingpowerisdefinedinHertzasonedividedbythe
shall be ≥99.5 weight % and the purity of each component for durationofthedecouplingchannel360°pulseinsecondsatthe
all other standard samples shall be ≥99 weight %. The power level being used for decoupling.
E2977 − 14
FIG. 1 Example of a Certificate of Analysis for an NMR Test Sample
6.1.5 The T relaxation time of the specific sample reso- 6.1.6 For sensitivity tests in which the signal-to-noise ratio
nance of interest should be measured on each sample to assure
(S/N) is insufficient, signal averaging may be used. If multiple
thattheequilibrationperiodisadequate.As T relaxationtimes
transients are collected, the resulting sensitivity value shall be
are dependent on the specific resonance observed, sample
adjusted as described in 7.2.
concentration, sample temperature, magnetic field strength,
6.1.7 In cases in which the natural abundance of the
and the concentration of certain impurities (most notably
measuredisotopeislow,itmaybenecessarytocorrecttheS/N
dissolvedoxygen),basingtheequilibrationperiodonliterature
fortheactualabundanceofthemeasuredisotopeinthesample
T values is insufficient. Unless experimental conditions such
13 15
itself. Examples of this are S/N determinations for C, N,
as temperature or field strength are changed, the T need only
and Si.
be determined once for a sealed sample.
E2977 − 14
6.1.8 For both sensitivity and resolution tests, decoupling (14), and benzaldehyde (15). The total contribution from all
should not be used unless specified. impurities (excluding water) in the final sample shall be less
than 1 mol% of the ethylbenzene concentration. The peak
7. Reporting Results
heightofthesignalfromdissolvedwaterinthesampleshallbe
smallerthanthatofthemethyltriplet.Forveryhigh-sensitivity
7.1 General Tests—Results may be reported from determi-
nations made by single procedures. systems, a more dilute sample may be used. Sensitivity shall
then be converted to and clearly reported as “equivalent to
7.2 Signal Averaging—If signal averaging is used, the
0.1%(v/v)ethylbenzeneat25°C.”Thefinalconcentrationand
measured sensitivity value shall be adjusted by dividing by the
its uncertainty shall be specified.
square root of the number of transients.
8.1.2 Data Acquisition—The following data acquisition pa-
7.3 Tests for Establishing and Meeting Specifications—
rameters shall be used:
Specification-level test results shall be reported as the average
8.1.2.1 Spectral Region—The larger of 30-ppm or 11-kHz
along with the standard deviation of the results from ten
(forprotonfrequenciesbelow400MHz)widthcenteredonthe
replications of the specified test made with no intervening
methylene resonance of ethylbenzene.
adjustments. For specification results, actual analyte concen-
8.1.2.2 Equilibration Delay—At least five times the T
trations and their uncertainties and tube dimensions
relaxation time of the ethylbenzene methylene resonance
(specifically, either the internal diameter or the external diam-
reduced by the acquisition time.
eter and wall thickness) shall be reported.
8.1.2.3 Pulse Flip Angle—90°.
8. Specific Test Procedures
8.1.2.4 Data Acquisition Time—4to8s.
8.1 H Sensitivity—This practice describes the determina-
8.1.2.5 Number of Transients—One.
tion of the proton sensitivity of the NMR system.
8.1.2.6 Receiver Gain—Optimized to take advantage of the
8.1.1 Sample—The sample is 0.1% (v⁄v) ethylbenzene in
full dynamic range of the receiver.
deuterochloroform (chloroform-d) containing 0.003 to 0.1%
8.1.2.7 Spinning Rate—The measurement should be speci-
(v/v) tetramethylsilane (TMS). The density of ethylbenzene is
fied as spinning or nonspinning. If the sample is spinning, its
3 3
0.86702 g/cm at 20°C, 0.862 64 g/cm at 25°C, and 0.858 28
rate shall be specified.
3 3
g/cm at30°C (5).Thedensityofchloroform-dis1.5007g/cm
3 3 8.1.3 Data Processing—The following data processing pa-
at 20°C (6), 1.4999 g/cm at 25°C, and 1.4906 g/cm at 30°C
3 3
rameters shall be used:
(7).ThedensityofTMSis0.6386g/cm at20°C,0.6329g/cm
8.1.3.1 Multiply the time domain data by an exponentially
at 25°C, and 0.6274 g/cm at 30°C (8).The ethylbenzene shall
-LB·t·π
decaying function of the form e where LB (line broaden-
be99.95%pureandfreefromchlorinatedby-products,suchas
ing)=1Hzand t = time value for each acquired data point.
(2-chloroethyl)benzene (9) and (1-chloroethyl)benzene (in
chloroform-d—5.12 and 1.88 ppm) (10), and care
...
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