Sampling and Analysis methods-GTR 2013-03-EtOH RCHO-03 2015-Comments-CA 17-03-2015-V2.docx
7.3. Sampling and analysis methods for ethanol (C2H5OH)
1) 7.3.1.Impinger and GC analysis of the liquid sample
2) Bag sampling and GC Analysis or photoacoustics measurement of diluted exhaust sample
3) Continuous diluted exhaust or bag sample and optical method
7.3.1.1. Sampling
Depending on the analytical method sample can be taken from the diluted exhaust from CVS or
from CVS bags.
From each phase of the test, a gas sample shall be taken from the corresponding diluted exhaust
bag and dilution air bag for analysis. A single composite dilution background sample can be
analysed instead.
The temperature of the diluted exhaust sample lines shall be more than 3 oC above the maximum
dew point of the diluted exhaust and less than 121oC.
7.3.1.2.. Gas chromatographic method
General description
The sample is introduced into a gas chromatograph (GC). The alcohols in the sample are separated
in a GC capillary column and subsequently detected and quantified by a flame ionization detector
(FID).
7.3.1.2.1. Sample transfer
Secondary sample storage media may be used to transfer samples from the test cell to the GC lab.
Good engineering judgement shall be used to avoid additional dilution when transferring the
sample from sample bags to secondary sample bags.
7.3.1.2.1.1 Secondary sample storage media.
Gas volumes shall be stored in sufficiently clean containers that minimally off-gas or allow
permeation of gases. Good engineering judgment shall be used to determine acceptable thresholds
of storage media cleanliness and permeation. In order to clean a container, it may be repeatedly
purged, evacuated and heated.
7.3.1.2.1.2. Sample storage
Secondary sample storage bags must be analysed within 24 hours and must be stored at room
temperature.
7.3.1.2.2. Sampling with impingers
7.3.1.2.2.1. For each phase of the test, two impingers are filled with 15 ml of deionized water and
connected in series and an additional pair of impingers is used for background sampling.
7.3.1.2.2.2. Impingers should be conditioned to ice bath temperature before the sampling collection
and keep them at that temperature during sample collection.
7.3.1.2.2.3. After sampling, the solution contained in each impinger is transferred to a vial and
sealed for storage and/ or transport before the analysis in the laboratory.
7.3.1.2.2.4. Samples shall be refrigerated at a temperature below 5 °C if immediate analysis is not
feasible samples must be analysed within 6 days.
7.3.1.2.2.5. Good engineering practice shall be used for sample volume and handling.
7.3.1.3. Instrumentation and apparatus
7.3.1.3.1. The sample may be injected directly into the GC or an appropriate preconcentrator
may be used. In case of preconcentration, this must be used for all necessary verifications and
quality checks.
7.3.1.3.2. A GC-column with an appropriate stationary phase of suitable length to achieve adequate
resolution of the C2H5OH peak shall be used for analysis. The column temperature profile and
carrier gas selection shall be taken into consideration when setting up the method selected to
achieve adequate C2H5OH peak resolution. The operator must aim for baseline separated peaks.
7.3.1.3.3. Good engineering judgment shall be used to zero the instrument and to correct for drift.
An example of good engineering judgement is described in §7.2.1.3.5.
7.3.1.4. Reagents and materials
Carrier gases:
- Nitrogen shall have a minimum purity of 99.998 percent.
- Helium shall have a minimum purity of 99.995 percent.
- Hydrogen shall have a minimum purity of 99.995 percent.
In case of sampling with impingers:
- Liquid standards of C2H5OH in pure water.
-C2H5OH 100%, analysis grade
7.3.1.5. Peak integration procedure
The peak integration procedure shall be performed as in §7.2.1.5.
7.3.1.6. Linearity
A multipoint calibration to confirm instrument linearity shall be performed according to §7.2.1.6.
7.3.1.7. Quality control
7.3.1.7.1. A nitrogen or air blank run shall be performed before running the calibration standard.
The ethanol concentration from the blank analysis must be below the LoD before the analysis may
proceed. A weekly blank run will provide a check on contamination of the complete system.
7.3.1.7.2. The calibration standard shall be analysed each day of analysis to generate the response
factors used to quantify the sample concentrations.
7.3.1.7.3. A quality control standard shall be analysed within 24 hours before the analysis of the
samples.
7.3.1.9. Calculations for GC 1/ from impingers and 2/diluted gas CVS
7.3.1.10. Limit of detection, limit of quantification
The limits of detection and of quantification shall be determined as in §7.2.1.9.
7.3.1.11. Interference verification
Interference and reducing interference error is described in §7.2.1.10.
7.4. SAMPLING AND ANALYSIS METHODS FOR
FORMALDEHYDE AND ACETALDEHYDE
7.4. Sampling and analysis for formaldehyde and acetaldehyde
1) Impinger or DNPH cartridges and HPLC analysis of the liquid sample
2) Continuous diluted exhaust or bag sample and optical method
7 4.1. Sampling
Depending on the analytical method sample can be taken from the diluted exhaust from CVS or
from CVS bags.
From each phase of the test, a gas sample shall be taken from the corresponding diluted exhaust
bag and dilution air bag for analysis. A single composite dilution background sample can be
analysed instead.
The temperature of the diluted exhaust sample lines shall be more than 3 oC above the maximum
dew point of the diluted exhaust and less than 121oC.
7.4.x. High performance liquid chromatography (HPLC)
7.4x.1. General description
Aldehydes are sampled with DNPH-impregnated cartridges. DNPH (2,4-dinitrophenylhydrazine)
carbonyls chemically react into their diphenylhydrazone derivatives. Elution of the cartridges is
done with acetonitrile. Analysis is carried out by high performance liquid chromatography (HPLC)
with ultraviolet (UV) detector at 360 nm or diodearray detector (DAD). Carbonyl masses ranging
between 0.02 to 200 µg are measured by this method.
7.4.1.2.1. Sampling by cartridges
7.4.1.2.1.1. DNPH-impregnated cartridges shall be sealed and refrigerated at a temperature less
than 4°C upon receipt from manufacturer until ready for use.
7.4.1.2.1.2.
7.4.1.2.1.3. The formaldehyde and acetaldehyde sampling system shall be of sufficient capacity so
as to collect samples of adequate size for analysis without significant impact on the volume of the
diluted exhaust passing through the CVS.
7.4.1.2.1.4. Good engineering practice shall be used to avoid sample breakthrough.
7.4.1.2.2. Sample storage
If samples are not analysed the same day as received, they must be refrigerated at a temperature
below 4°C. Refrigerated samples are stable for up to 30 days.
7.4.1.2.3. Sample preparation
Elute the cartridges by removing their caps, extract with acetonitrile and run the extract into glass
storage bottles. Transfer the solution from each cartridge to glass vials and seal with new septum
screw caps.
7.4.1.3. Instrumentation
- Liquid autosampler
- HPLC-UV or HPLC-DAD
7.4.1.4. Reagents
Reagents shall be:
(a) Acetonitrile, HPLC grade
(b) Water, HPLC grade
(c) 2,4 DNPH, purified; unpurified DNPH must be recrystallized twice from acetonitrile. The
recrystallized DNPH is checked for contaminants by injecting a diluted solution of DNPH in
contaminant free acetonitrile into the HPLC.
(d) Carbonyl/2,4-dinitrophenylhydrazone complexes may be purchased or prepared in the
laboratory. In-house standards must be recrystallized at least three times from 95 percent ethanol.
(e) Sulfuric acid, or perchloric acid, analytical reagent grade
(f) DNPH-impregnated cartridges
7.4.1.4.1. Stock solution and calibration standard
7.4.1.4.1.1. A stock calibration standard is prepared by diluting the target carbonyl/2,4-DNPH
complexes with acetonitrile. A typical stock calibration standard contains 3.0 µg/mL of each target
carbonyl compound.
7.4.1.4.1.2. Stock calibration standards of other concentrations may also be used.
7.4.1.4.1.3. A calibration standard is prepared when required by diluting the stock calibration
solution, making sure that the highest concentration of the standard is above the expected test level.
7.4.1.4.2. Control standard
A quality control standard, containing all target carbonyls/2,4 DNPH complexes within the typical
concentration range of real samples is analysed to monitor the precision of the analysis of each
target carbonyl.
7.4.1.4.2.1. The control standard may be purchased, prepared in the laboratory from a stock
solution different from the calibration standard, or prepared by batch mixing old samples, spiking
it with a stock solution of target compounds, and stirring for a minimum of 2 hours. If necessary,
the solution is filtered using filter paper to remove precipitation. All target compounds except
acrolein have been found to be stable in the control standard.
7.4.1.5. Procedure
7.4.1.5.1. Vials containing the field blank, calibration standard, control standard, and samples for
subsequent injection into the HPLC shall be prepared.
7.4.1.5.2. Columns, temperatures and solvent/eluents shall be chosen to achieve adequate peak
resolution. Columns of suitable polarity and length shall be used. The method shall specify column,
temperature, detector, sample volume, solvents and flow.
7.4.1.5.3. Good analytical judgment shall be used to evaluate the quality of the performance of the
instrument and all elements of the protocol to provide a robust method of analysis.
7.4.1.6. Linearity
A multipoint calibration to confirm instrument linearity shall be performed according to §7.2.1.6.
7.4.1.7. Quality control
7.4.1.7.1. Field blank
One cartridge shall be analysed as a field blank for each emission test. If the field blank shows a
peak greater than the limit of detection (LOD) in the region of interest, the source of the
contamination must be investigated and remedied.
7.4.1.7.2. Calibration run
The calibration standard shall be analysed each analysis day to generate the response factors used
to quantify the sample concentrations.
7.4.1.7.3. Control standard
A quality control standard shall be analysed at least once per 7 days.
7.4.1.8.
7.4.1.9. Limit of detection, limit of quantification
The LoD for the target analytes must be determined for:
(a) new instruments,
(b) after making instrument modifications which can affect the LoD, and
(c) at least once per year.
7.4.1.9.1. To perform the calculations, it is necessary to perform a multipoint calibration consisting
of at least four “low” concentration levels, each above the LoD, with at least five replicate
determinations of the lowest concentration standard.
7.4.1.9.1.2. The maximum allowable LoD of the hydrazine derivative is 0.0075 µg/mL.
7.4.1.9.1.3. The calculated laboratory LoD must be equal to or lower than the maximum allowable
LoD.
7.4.1.9.1.4. All peaks identified as target compounds that are equal to or exceed the maximum
allowable LoD must be reported.
7.4.1.9.1.5. For the purpose of calculating the total mass of all species, the concentrations of the
compounds below the LoD are considered to be zero.
.
Carbonyl mass emission calculation per test phase
Final mass calculation should be referred to Annex 7 paragraph 3.2.1(
7.4.1.10. Interference verification
To reduce interference error, proof of chemical identity may require periodic confirmations using
an alternate method and/or instrumentation, e.g., alternative HPLC columns or mobile phase
compositions