FprEN 15199-2:2020 (E) 511Produits pétroliers — Détermination de la répartition dans l’intervalle de distillation par méthode par chromatographie en phase gazeuse — Partie 2 : Distillats sévères et residualsMineralölerzeugnisse — Gaschromatographische Bestimmung des Siedeverlaufes — Teil 2: Schweröle und RückstandsölePetroleum products — Determination of boiling range distribution by gas chromatography method — Part 2: Heavy distillates and residual fuelsE0 00 202006Formal VoteCEN 1European StandardEuropean StandardEN 15199-2FprEN 15199-2:2020 0Falsch2 NENGaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin19 2Überschrift 2Überschrift 1 0 STD Version 2.9p50 1C:\Users\rro\Desktop\neu FAM\CEN 19 WG 9\EN 15199-2\EN_15199-2_ method new revision 09062020.docx CEN/TC 19

Date:  2025-12

prEN 15199-2:2026

CEN/TC 19

Secretariat:   NEN

Petroleum products — Determination of boiling range distribution by gas chromatography method — Part 2: Heavy distillates and residual fuels

Mineralölerzeugnisse — Gaschromatographische Bestimmung des Siedeverlaufes — Teil 2: Schweröle und Rückstandsöle

Produits pétroliers — Détermination de la répartition dans l'intervalle de distillation par méthode de chromatographie en phase gazeuse — Partie 2 : Fiouls lourds et fiouls résiduels

ICS:

Descriptors:

Contents Page

European foreword 3

1 Scope 4

2 Normative references 4

3 Terms and definitions 4

4 Principle 6

5 Reagents and materials 6

6 Apparatus 9

7 Sampling 11

8 Preparation of the apparatus 11

8.1 Gas chromatograph preparation 11

8.2 System performance check 11

9 Sample and reference material preparation 11

10 Calibration 12

11 Procedure 13

12 Visual inspection of the chromatograms 14

13 Calculation 15

14 Expression of results 15

15 Precision 15

15.1 General 15

15.2 Repeatability 15

15.3 Reproducibility 15

16 Test report 16

Annex A (normative) Calculation procedure 18

Annex B (normative) System performance check 21

Annex C (normative) Boiling points of n-alkanes 23

Annex D (informative) Additional guidance for the calculation algorithm 25

Bibliography 29

European foreword

This document (prEN 15199-2:2026) has been prepared by Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”, the secretariat of which is held by NEN.

This document is currently submitted to the CEN Enquiry.

This document will supersede EN 15199-2:2020.

The main change in this edition is the allowance of alternative carrier gasses.

EN 15199 consists of the following parts, under the general title Petroleum products — Determination of boiling range distribution by gas chromatography method:

— Part 1: Middle distillates and lubricating base oils;

— Part 2: Heavy distillates and residual fuels;

— Part 3: Crude oil;

— Part 4: Light fractions of crude oil.

This document specifies the determination of boiling range distribution of materials with initial boiling points (IBP) above 100 °C and final boiling points (FBP) above 750 °C. For testing materials with initial boiling points (IBP) above 100 °C and final boiling point (FBP) below 750 °C, Part 1 of the standard can be used. For testing materials with initial boiling points (IBP) below 100 °C and final boiling points (FBP) above 750 °C, such as crude oils, Part 3 is applicable. Part 4 describes the determination of boiling range distribution of hydrocarbons up to n-nonane in crude oil.

This document is a joint development between the EI [5], ASTM [4] and CEN.

This document specifies a method for the determination of the boiling range distribution of petroleum products by capillary gas chromatography using flame ionization detection. The document is applicable to materials having a vapour pressure low enough to permit sampling at ambient temperature, and which have a boiling range of at least 100 °C. The document is applicable to materials with initial boiling points (IBP) above 100 °C and final boiling points (FBP) above 750 °C, for example, heavy distillate fuels and residuals. The method is not applicable to bituminous samples.

The test method is not applicable for the analysis of petroleum or petroleum products containing low molecular weight components (for example naphthas, reformates, gasolines) or middle distillates like Diesel and Jet fuel.

Petroleum or petroleum products containing blending components, which contain hetero atoms (for example alcohols, ethers, acids, or esters) or residue, are not to be analysed by this test method.

NOTE For the purposes of this document, the terms “% (m/m)” and “% (V/V)” are used to represent respectively the mass fraction and the volume fraction.

WARNING — The use of this document can involve hazardous materials, operations and equipment. This document does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

EN ISO 3170, Hydrocarbon Liquids — Manual Sampling (ISO 3170)

EN ISO 3171, Petroleum liquids — Automatic pipeline sampling (ISO 3171)

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

initial boiling point

IBP

temperature corresponding to the retention time at which a net area (3.7) counts equal to 0,5 % of the total sample area (3.6) under the chromatogram is obtained (see Figure 1)

3.2

final boiling point

FBP

temperature corresponding to the retention time at which a net area (3.7) counts equal to 99,5 % of the total sample area (3.6) under the chromatogram is obtained (see Figure 1)

Key

Figure 1 — Typical chromatogram

3.3

area slice

area resulting from the integration of the chromatographic detector signal within a specified retention time interval

Note 1 to entry: In area slice mode peak detection parameters are bypassed and the detector signal integral is recorded as area slices of consecutive, fixed duration time interval.

3.4

corrected area slice

area slice (3.3) corrected for baseline offset by subtraction of the exactly corresponding area slice (3.3) in a previously recorded blank (non-sample) analysis

3.5

cumulative corrected area

accumulated sum of corrected area slices (3.4) from the beginning of the analysis through a given retention time, ignoring any non-sample area for example of solvent

3.6

total sample area

cumulative corrected area (3.5), from the initial area point to the final area point, where the chromatographic signal has returned to baseline after complete sample elution

3.7

net area

cumulative area counts for the sample minus the cumulative area count for the blank

3.8

recovery

ratio of the cumulative area count of the sample to that of the reference material (external standard) corrected for dilution and material weights combined with the percentage of light ends, if applicable

A test portion is introduced into a gas chromatographic column, which separates hydrocarbons in the order of increasing boiling point. The column temperature is raised at a linear reproducible rate and the area under the chromatogram is recorded throughout the analysis. Boiling points are assigned to the time-axis from a calibration curve, which is obtained by running a mixture of known n-alkanes covering the test portion boiling range, under the same conditions. From these data, the boiling range distribution is obtained. The recovery (3.8) at a specified temperature is determined by comparing the area under the chromatogram with that of a reference standard which has been completely eluted. The temperature at which the recovery was measured is recorded. If the found recovery is less than 100 %, the final boiling point (3.2) is reported as 720 °C or 750 °C at that recovery.

Several SIMDIS methods are standardized test methods and each one is dedicated to a certain boiling point range or product.

EN ISO 3924 [2] is limited to products having an initial boiling point greater than 55 °C, a final boiling point lower than 538 °C and having a vapour pressure sufficiently low to permit sampling at ambient temperature.

EN 15199-1 [1] is applicable to materials having a boiling range of at least 100 °C, an initial boiling points (IBP) above 100 °C and final boiling points (FBP) below 750 °C, for example, middle distillates and lubricating base stocks.

EN 15199-3 is applicable to crude oils. The boiling range distribution and recovery up to C₁₀₀ or C₁₂₀ can be determined.

Unless otherwise stated, only chemicals of recognized analytical quality shall be used.

5.1 Carrier gas, helium, nitrogen or hydrogen, of at least 99,999 % (V/V) purity. Any oxygen present is removed by a chemical resin filter.

WARNING — Follow the safety instructions from the filter supplier.

CAUTION — Helium and nitrogen are compressed gases under high pressure. Hydrogen is an extremely flammable gas under high pressure.

5.2 Hydrogen, grade suitable for flame ionization detectors.

5.3 Compressed air, suitable for flame ionization detectors.

5.4 Alkanes, n-alkanes of at least 98 % (m/m) purity from C₅ to C₁₀, C₁₂, C₁₄, C₁₆, C₁₈, C₂₀, C₂₄ and C₂₈.

NOTE The calibration mixture from EN ISO 3924 [2] is also suitable.

5.5 Polyethylene wax solution^[1].

5.6 Carbon disulfide (CS₂), with a minimum purity of 99,7 % (V/V).

WARNING — Extremely flammable and toxic.

CAUTION — It is recommended that all work with CS₂ is carried out in an explosion protected fume cupboard.

Cyclohexane (C₆H₁₂)—(>99 % pure) may be used in place of CS₂ for the preparation of the calibration mixture. However, the precision of this method is based on calibration mixtures, reference material and samples prepared with CS₂ only.

5.7 Calibration mixture

Dissolve 0,1 g of Polyethylene wax solution (5.5) in 7 ml CS₂ (5.6), warming gently if necessary. Prepare an equal volume mixture of alkanes (5.4) and add 10 µl to the Polyethylene wax solution.

NOTE 1 Commercially available alkane standards are suitable for column performance checks.

NOTE 2 The calibration mix is used to determine the column resolution, skewness of the C₂₀ peak, and retention time versus boiling point calibration curve.

5.8 Reference materials

5.8.1 A reference material has two functions:

— External Standard: to determine the recovery (3.8) of samples by comparing the total sample area (3.6) of the reference material with the total sample area (3.6) of the unknown sample.

— Boiling Point Distribution Standard: to check the proper functioning of the system by comparing the results with a known boiling point distribution on a routine basis. Typical example is given in (5.8.2).

5.8.2 Reference Material 5010, a reference sample that has been analysed by laboratories participating in the test method cooperative study. Consensus values for the boiling range distribution of this sample are given in Table 1.

5.8.3 Binary gravimetric blend, a binary distillate mixture with boiling points ranges that gives a baseline at the start, a baseline between the two peaks and an end time that is as close to the end of the chromatogram as possible (see Figure 2 and Clause B.3). This mixture is used to check the relative response of the two distillates and to check the baselines at the start, middle and end of the chromatogram.

Table 1 — Reference material 5010

Key

Figure 2 — Typical chromatogram of binary gravimetric blend distillate

6.1 Gas chromatograph, with the following performance characteristics.

6.1.1 Flame ionization detector, connected to the column so as to avoid any cold spots. The detector shall be capable of operating at a temperature at least equivalent to the maximum column temperature employed in the method.

6.1.2 Column temperature programmer, capable of linear programmed temperature operation over a range of 10 °C above ambient to 450 °C.

6.1.3 Sample inlet system, consisting of a programmable temperature vaporizer (PTV) or cold on-column (COC) injection port. The maximum temperature of the injection device shall be equal to, or higher than, the final oven temperature. The minimum temperature shall be low enough to prevent sample or solvent flashback, but high enough to allow sample focusing at the front of the column. Table 2 contains the typical operating conditions.

6.2 Column

6.2.1 The capillary column should sit just below the flame tip and it is recommended that the orifice of the jet should be 0,6 mm minimum to prevent frequent blocking with silicones.

6.2.2 Use a metal column with 0,53 mm internal diameter and coated with methyl silicone. Commercially available columns with film thickness (d_f) = 0,09 µm (for analysis up to C₁₂₀) and (d_f) = 0,17 µm (for analysis up to C₁₀₀) have been found to be satisfactory.

The column resolution, R, shall be at least 2 and not more than 4 (see Clause B.2).

6.2.3 Use some form of column bleed compensation to obtain a stable baseline. This may be carried out by subtraction of a column bleed profile previously obtained using exactly the same conditions as used for the sample analysis, by injecting the same volume, using solvent for the blank run and sample dilution from one batch taken at the same time, to avoid differences due to contamination.

Table 2 — Typical operating conditions for gas chromatograph

6.3 Carrier gas control

The chromatograph shall be able to deliver a constant carrier gas flow over the whole temperature range of the analysis.

6.4 Micro-syringe, of appropriate volume, e.g. 10 µl, for introduction of 1 µl of the calibration mixture and test portions. Plunger in needle syringes are not recommended due to excessive carry over of heavy ends to the following analysis.

6.5 Volumetric flask, 10 ml capacity.

6.6 Refrigerator, shall be of an explosion-protected design.

6.7 Analytical balance, capable of weighing to the nearest 0,1 mg.

Samples shall be taken as specified in EN ISO 3170 or EN ISO 3171 (see the requirements of national standards or regulations for the sampling of petroleum products for further information).

Store samples in either glass or metal containers. Plastic containers for sample storage shall not be used as prolonged contact with the sample can cause contamination of the sample due to possible leaching of the plasticizer.

8.1.1 Set up and operate the gas chromatograph (6.1) in accordance with the manufacturer’s instructions.

Typical operating conditions are shown in Table 2.

8.1.2 Deposits can form on the jet from combustion of decomposition products from the liquid stationary phase. These will affect the characteristics of the detector and shall be removed.

The following parameters are affected by deposits on the jet: increase in inlet pressure; FID difficult to light; increase in the CS2 response and an off specification reference material. To clean the jet, an ultrasonic cleaner with a suitable solvent, and a cleaning wire may be used.

Check the system performance at the intervals given and by the procedures specified in Annex B.

9.1 Mix the sample by shaking, warming prior to shaking where necessary.

9.2 Weigh approximately 0,1 g to 0,3 g of the sample to the nearest 0,1 mg, into a clean 10 ml volumetric flask (6.5) and add 5 ml to 7 ml CS₂ (5.6).

Shake the mixture to completely dissolve the test portion and then add CS₂ (5.6) to the mark. Immediately transfer the solution to auto test portion vials, seal, and store in a refrigerator until ready for use.

If the density of the sample is known, the test portion may be prepared on a mass/mass basis, and the following correction applied:

(1)

where

The density is quoted at 20 °C as a temperature approximately ambient in most laboratories. Appropriate adjustments should be made if the laboratory temperature is outside (20 ± 5) °C.

9.3 Sample preparation is important to calculate the recovery (3.8) of the sample. The sample may be prepared by weighing the sample in a 10 ml flask as specified. Using this procedure, it is not required to know or measure the density of the sample. Due to the low boiling point and the health restrictions of CS₂ it is preferred to prepare the sample by weight and correct for the density.

9.4 When the density is unknown and therefore no correction can be applied, the error in the recovery calculation is minor. Not correcting for density can result in a deviation of at most 1 % on the recovery (3.8) for the density range 700 kg/m³ to 1 000 kg/m³.

10.1 It is highly recommended to carry out the steps given in 10.2 to 10.4 each day before sample analysis. The first run of the day shall not be a blank, a reference material or a sample, due to the possible elution of extraneous components, which have built up in the injector, but it may be the calibration mixture (5.7).

10.2 Run the calibration mixture (5.7) as specified in Clause 11.

Take care to ensure the test portion volume chosen does not allow any peak to exceed the linear range of the detector, or overload the column. Determine the skewness according to Annex B System Performance (B4). A skew of > 3 indicates the sample is too concentrated and a skew of < 1 indicates an old column or dirty liner. As a guide, 1 µl of the calibration mixture (5.7) has been found to be suitable for columns with film thickness less than 0,17 µm.

10.3 Record the retention time of each component and plot the retention time versus the atmospheric boiling point for each component to obtain the calibration curve.

NOTE The atmospheric boiling points of the alkanes (5.4 and 5.5) are given in Annex C.

A typical chromatogram of the calibration mixture (5.7) is given in Figure 3 and a typical calibration curve is given in Figure 4.

10.4 Run the reference material (5.8.2) using the specified procedure in Clause 11. Calculate the boiling range distribution of the reference material by the procedures specified in Annex A and compare this with the consensus values for the reference material used.

If the results are not within the specified range, it is advised to carefully follow the manufacturer’s instructions regarding chromatographic problem solving and related diagnostics.

Key

Figure 3 — Typical chromatogram of calibration mixture

Key

Figure 4 — Typical calibration curve

11.1 Run a solvent (blank) baseline analysis before the first sample analysis, and then after every five samples. Using the data system, merge the blank baselines and the subsequent analyses and observe the last part of the chromatogram. The baseline shall look like example a in Figure 5.

NOTE It is good practice to follow each test portion with a CS₂ (5.6) blank to prevent carryover of heavy non-volatile material into the next analysis.

a) good baseline merging	b) bad baseline parallel (high FBP)	c) bad baseline crossing (low FBP)

Figure 5 — Baselines

The peak shape of the CS₂ and the identification of a constant baseline at the end of the run is critical to the analysis. Constant attention shall be given to all factors that influence the peak shape and the baseline stability, e.g. column substrate bleed, septum bleed, detector temperature control, constancy of carrier gas (5.1) flow, leaks and instrument drift. The peak shape of the CS₂ is influenced by the cleanliness of the liner and or the connection between the column and the liner (Figure 6). The baseline at the end of each analysis shall merge with the baseline of the blank run associated with it. Both signals shall merge to confirm integrity; if they do not, the analysis shall be repeated.

Key

Figure 6 — Solvent Peak Shape

11.2 Run the calibration and the reference sample according to Clause 10 under the same analysis circumstances, see Table 2.

11.3 Verify the system performance check as specified in Annex B, and when they passed the criteria, the system is ready for sample analysis.

11.4 It is recommended to repeat the calibration and or the reference sample at the end of the sample analysis sequence to monitor the instruments performance during the sequence.

Using the data system, expand the chromatogram of the secondary working standard or test portion, by 5 times. Merge the blank baseline and observe the following points:

The start of the area of interest is taken at a point on the baseline where the blank and the test portion baselines are merged. This is taken before the start of the test portion and after the end of the solvent.

The end of the area of interest of the test portion is taken at the retention time equivalent to the required temperature at which the recovery (3.8) is determined.

The end of the area of interest of the secondary working standard is taken at a point on the baseline where the blank and standard baselines are merged. This is taken before the end of the temperature programme.

The start of the test portion is determined as given in Clause A.5.

The end of the test portion is determined as given in Clause A.6.

Use the calculation protocol given in Annex A and the guidance in Annex D for the calculation of the results.

Report the tabulated results as follows:

a) report all temperatures to the nearest 1 °C;

b) report all percentages to the nearest 1 % (m/m);

c) report the 0,5 % (m/m) point as the initial boiling point (3.1), and the recovery (3.8) at selected final elution temperature (720 °C or 750 °C);

d) report intermediate percentages as required, at intervals of not less than 1 % (m/m).

The precision was determined by statistical examination of inter-laboratory study (ILS) results using EN ISO 4259:1995 [4] in a matrix of samples with properties in the range shown in Table 3.

Other carrier gasses for simulated distillation methods can result in a bias. The ILS on which this document is based, was inconclusive on whether the laboratories had used other gasses than helium. Nitrogen or hydrogen are allowed as carrier gas, but the precision in the clause cannot be applied.

The difference between two independent results obtained using this method for test material considered to be the same in the same laboratory, by the same operator using the same equipment within short intervals of time, in the normal and correct operation of the method that is expected to be exceeded with a probability of 5 % due to random variation, conforms to the value given in Table 3.

The difference between two independent results obtained using this method for test material considered to be the same in different laboratories, where different laboratory means a different operator, different equipment, different geographic location, and under different supervisory control, in the normal and correct operation of the that is expected to be exceeded with a probability of 5 % due to random variation, conforms to the value given in Table 3.

Table 3 — Precision values

The test report shall specify at least:

a) a reference to this document and its year of publication, i.e. prEN 15199-2:2026;

b) the type and complete identification of the material tested;

c) the result of the test (see Clause 14);

d) any deviation, by agreement or otherwise, from the standard procedures specified;

e) any unusual features observed;

f) the date of the test.

1. 
   (normative)
   
   Calculation procedure
   1. Application

The algorithm given in this Annex only applies for a slice width of 0,1 s to 0,2 s (10 Hz to 5 Hz). The chromatogram for the reference material (5.8), the sample, and the baseline shall be zeroed. The baseline chromatogram is subtracted from the Reference Material 5010 (5.8.2) and from the sample chromatogram in order to obtain the net area (3.7). An extended procedure is given as informative guidance in Annex D.

• 1. Starting conditions

The following data are required for the commencement of calculations:

a) sample data array (N data points);

b) reference material data array (N data points);

c) blank data array (N data points);

d) processed data file from calibration run with retention times of n-alkanes (5.4 and 5.5);

e) boiling points of n-alkanes (5.4 and 5.5) used in calibration run;

f) start sample time;

g) end sample time.

The data collection of the test portion or reference shall be identical to the used data points in the blank.

• 1. Zero sample or reference chromatogram

A.3.1 Subtract each blank slice area from the corresponding sample slice area.

A.3.2 Average the first twenty time slices from the subtracted slice areas.

A.3.3 Subtract the average slice area from each subtracted time slice to zero the chromatogram. Set negative numbers to zero.

• 1. Sample area

Calculate the total sample area (3.6) by summing each of the corrected area slices (3.4).

• 1. Start of sample elution time

By inspection of the chromatogram, select a start time for the area of interest, after the elution of the solvent, where the baseline merges with the blank. The time slice, after this point, where the average rate of change first exceeds 0,000 01 %/s of the total area is defined as the start of sample. Report this time and/or indicate it on the chromatogram.

• 1. End of sample elution time

The end of sample elution time is set by the user at 720 °C or 750 °C. It is the time equivalent to the temperature at which the recovery (3.8) is to be determined. This time shall be before the end of the temperature programme.

• 1. End of reference material elution time

By inspection of the chromatogram, select the end time for the area of interest, before the end of the temperature programme, where the baseline merges with the blank. The time slice, before this point, where the average rate of change first exceeds 0,000 01 %/s of the total area is defined as the end of external standard. Report this time and/or indicate it on the chromatogram.

• 1. Corrected sample or reference material area

Calculate the total corrected sample area by summing the area slices (3.3) from the start of sample to the end of sample.

• 1. Normalization

A.9.1 Determine the area/weight factor for the reference material by summing all the area slices (3.3) in the external standard and dividing by the weight of the external standard taken in 10 ml CS₂ (5.6).

A.9.2 Determine the area/weight of the sample by summing all the area slices (3.3) and dividing by the weight of the sample taken in 10 ml CS₂ (5.6).

A.9.3 Determine the % recovery (3.8) by:

(A.1)

where

A.9.4 To convert time slices to area percents, start with the time slice corresponding to the start of the sample and continue to the time slice corresponding to that set by the User and divide by the % recovery (3.8) determined in A.9.3.

• 1. Conversion of retention time to percent off
     1. Initial boiling point

Starting with the time slice corresponding to start of sample, add the normalized area percents until the total is equal to, or greater than, 0,5 %. Linearly interpolate to find the time corresponding to exactly 0,5 % of the total corrected sample area.

• • 1. Intermediate boiling points

For each percent off between 1 % and 99 %, find the retention time where the cumulative area percent is equal to or greater than the percent being determined. Use linear interpolation when the cumulative sum exceeds the percent being determined.

• 1. Conversion of retention times to boiling points

A.11.1 For each retention time determined in A.10.1 to A.10.2, find the pair of calibration retention times that bracket the percent off time of interest.

A.11.2 Calculate the boiling point corresponding to the percent off retention time, BPi, in °C, from the following Formula (A.2):

(A.2)

where

A report giving percent off at selected boiling point intervals may be calculated in an analogous manner.

Report all results in accordance with Clause 14.

1. 
   (normative)
   
   System performance check
   1. Frequency

This procedure may be carried out as part of the boiling range calibration (see Clause 10)

Carry out a run on the calibration mixture (5.7), using identical conditions and injection volumes to those used for the sample analysis, whenever:

a) the analytical system and conditions have been altered in any way since the last performance check was carried out, or

b) the results obtained for the secondary working standard fall outside the permitted limits.

Determine the characteristics specified in Clauses B.2 to B.4.

• 1. Column resolution

Determine the column resolution, R, using the C₅₀ and C₅₂ peaks (see Figure 3) and the following Formula (B.1):

(B.1)

where

Resolution as determined above shall be at least 2, but no greater than 4.

• 1. Detector response (gravimetric blend)

Use a binary gravimetric blend (5.8.3) distillate to determine the detector response. Since the most critical area of the chromatogram is where column bleeding occurs, the binary blend is also used as a recovery test. The binary blend shall have the following characteristics:

a) the lower boiling distillate shall not interfere with the solvent;

b) there shall be a baseline between distillates;

c) the higher boiling point distillate shall elute totally and as close to the end of the temperature programme as possible;

d) the ratio of the areas of the two distillates shall be constant, which is checked by measuring the % recovered at 400 °C which shall be: (32,4 ± 0,6) % (m/m).

If one of these criteria is not met, it is advised to carefully follow the manufacturer’s instructions regarding chromatographic problem solving and related diagnostics.

• 1. Skewing of peak

Determine the skewing of the peak as the ratio A/B as shown in Figure B.1, for the C20 peak, where;

A is the width of the leading part of the peak at 5 % of the peak height;

B is the width of the following part of the peak at 5 % of the peak height.

The ratio shall not be less than 1 nor greater than 3.

Key

Figure B.1 — Peak skewness

1. 
   (normative)
   
   Boiling points of n-alkanes

The boiling points of n-alkanes (5.4) used for construction of the calibration curve are given in Table C.1.

Table C.1 — Boiling points of n-alkanes

1. 
   (informative)
   
   Additional guidance for the calculation algorithm
   1. Zeroing of the reference material chromatogram

D.1.1 Examine the chromatogram obtained for Reference Material 5010 (5.8.2), and ensure, by visual inspection of the chromatogram in the data system, that the first 5 slices contain neither sample nor solvent elution.

D.1.2 Set up an array that contains slices obtained from the Reference Material 5010 chromatogram. Calculate the average of the first five area slices (3.3). Subtract the average slice area from each slice in the Reference Material 5010 chromatogram. Set negative numbers to zero.

D.1.3 Zero the blank baseline chromatogram by carrying out an analogous calculation as in D.1.2.

D.1.4 Subtract the blank baseline from the Reference Material 5010 chromatogram. Subtract each zeroed blank baseline slice from the corresponding zeroed Reference Material 5010 slice. If there are negative slices, set the slice values to zero.

D.1.5 Determine the end of elution time of Reference Material 5010.

Since it is a requirement that the sample chosen to obtain a response factor shall fully elute prior to the final elution time, the end of sample elution for this chromatogram should be determined as specified in EN 15199-1 [1], using the algorithm to determine the time the signal of the completely eluted sample returns to baseline.

D.1.6 Determine the area of the chromatogram for Reference Material 5010. Determine the end time of solvent elution. Sum all of the slices from the end of solvent elution to the end of sample elution. This is the area of the standard, A_STD.

D.1.7 Calculate the boiling point distribution of Reference Material 5010. The resulting corrected slices obtained for Reference Material 5010 are submitted to a calculation for boiling point distribution as in EN 15199-1 [1]. A comparison of the values obtained with the consensus values listed in Table 1 is made and all the boiling point values should fall within the specified windows. If this requirement is not met, correct any chromatographic problems prior to proceeding with sample analysis.

Typical problems found in this step are: contaminated solvent; problems in sample preparation; sample residue in the inlet or column, or both; quality of the baseline used, a partially blocked detector jet, or a combination thereof.

• 1. Zeroing of sample chromatograms

D.2.1 In the case of crude oil analysis or samples in which the solvent peak is not resolved from the sample components, ensure, by visual inspection of the chromatogram in the data system, that the first 5 slices contain neither sample nor solvent elution. If there is sample elution, decrease the number of slices for the averaging to 3.

D.2.2 Zero the sample chromatogram. Proceed in a manner analogous to that specified in D.1.2.

D.2.3 Zero the blank baseline chromatogram. Carry out an analogous calculation as in D.1.3.

• 1. Blank baseline subtraction from the sample chromatogram

Carry out an analogous calculation as in D.1.4.

• 1. Quenching correction

D.4.1 For crude oil samples, a quenching factor is used to correct for the diminished FID response when the CS₂ co-elutes with sample components. This factor is applied to the time segment corresponding to the elution of CS₂. In the interlaboratory study, the factor of 1,930 was applied. This value is determined from experiments made by dissolving butane, pentane, and hexane in toluene.

The solution is analysed by injecting it under conditions identical to sample analysis. The areas for the components are compared to the areas obtained by gradually adding weighed aliquots of CS₂ to the original solution. Samples that do not have components that co-elute with solvent, for example, residues or the Reference Material 5010, do not require the quenching correction.

D.4.2 Determine the quenching interval. Select the time that the solvent peak starts to elute. Determine when the solvent peak has eluted. Note the times of this interval in minutes.

D.4.3 Locate the slices of the quenching interval. For samples in which the solvent component co-elutes with the sample chromatogram (that is, crude oils), determine the quenching interval, QI, as specified in D.4.2. Find the closest slice corresponding to the beginning of elution of the solvent peak as well as the final slice corresponding to the end of elution of the solvent peak.

D.4.4 Correct the diminished response of the interval by multiplying each slice of this interval by the quenching factor, QF. Use the value as discussed in D.4.1.

• 1. Determination of the sample final elution time (t_FE)

Determine the time at which the oven reaches the isothermal portion of the temperature program. This is usually recognized as an inflection point in the baseline. This point is called the final elution time (t_FE). The conversion of this slice to temperature will yield the final elution temperature, T_FE. This conversion is carried out in D.9.4.

• 1. Determination of the sample area

The net sample area is obtained by adding all slices from time t = 0 to the final elution time, t_FE. This net area (3.7) is the A_SMP.

• 1. Response factor

Calculate the response factor, RF, as follows:

(D.1)

where

NOTE The mass term in Formula (D.1) is expressed as a fraction of the mass of solute and solvent.

• 1. Calculation of the percentage recovery

The percentage recovery, %RC, is defined as:

(D.2)

where

Since:

(D.3)

where

Substituting Formula (D.3) for the value of ME in Formula (D.2) yields:

(D.4)

Substituting Formula (D.1) in Formula (D.4) for the value of RF yields:

(D.5)

Determine whether the %recovery (3.8), (%RC) falls below the recovery threshold (Rt) limits set. If it is less than or equal to the recovery threshold (Rt), use the %recovery (%RC) determined by Formula (D.5). If the %recovery (3.8) is greater than the recovery threshold (Rt), then the recovery is set to 100 %. If the %recovery is larger than 102 % (standard deviation of the residue), repeat the analysis or determine the chromatographic problem.

• 1. Determination of the boiling point distribution

D.9.1 Multiply each slice of the sample chromatogram by the % recovery as established in Clause D.8. Divide each slice by the total area of the sample obtained in Clause D.6. This will express the slices in a percent scale.

D.9.2 Add the slices that will yield 0,5 %, 1 %, 2 %, ... % recovery. Determine, at 1 % intervals, the time of the slice yielding exactly 0,5 %, 1 %, 2 %, ...%recovery. Use an interpolation procedure to find the fractional slices required to yield exactly 0,5 %, 1 %, 2 %, ...% recovery.

D.9.3 Stop the calculation carried out in D.9.2 when obtaining a slice summation equal to the nearest whole integer of the % recovery.

D.9.4 Convert the retention times to boiling points as outlined in the algorithm in A.11.2. Use the boiling point temperatures listed in Table C.1. For each retention time obtained in D.9.2, find the corresponding temperature from the boiling point vs. retention time function as shown in Figure 4. Calculate the corresponding boiling points as determined in Clause A.10.

• 1. Calculation of cut point intervals

D.10.1 For the two temperatures that define the cut point interval, find the two corresponding slices.

D.10.2 Using the calibration curve, convert this temperature range to a time range.

D.10.3 Convert the time range to a slice number range by multiplying by 60 and dividing by the slice width in seconds.

D.10.4 Sum the normalized slices, starting with the initial slice of the cut and terminating with the last slice after the cut. This sum will be equal to the % mass of the cut.

D.10.5 The % recovery, % RC, determined at a temperature T_RC that is equal to or less than t_FE may be determined at a new temperature T_N by using the following Formula (D.6):

(D.6)

where

The use of this formula for values T_N > T_FE is not recommended.

Bibliography

[1] EN 15199-1, Petroleum products — Determination of boiling range distribution by gas chromatography method — Part 1: Middle distillates and lubricating base oils

[2] EN ISO 3924, Petroleum products — Determination of boiling range distribution — Gas chromatography method (ISO 3924)

[3] EN ISO 4259:1995,^[2] Petroleum products — Determination and application of precision data in relation to methods of test (ISO 4259:1992/Cor 1:1993)

[4] ASTM D7169, Standard test Method for Boiling Point Distribution of Samples with residues Such as Crude Oils and Atmospheric and Vacuum Residues by High Temperature Gas Chromatography

[5] IP 507, Petroleum products — Determination of boiling range distribution by gas chromatography method — Part 2: Heavy distillates and residual fuel

1. Polywax is the tradename of fully saturated homopolymers of ethylene supplied by Baker Hughes Holdings LLC. This information is given for the convenience of users of this document and does not constitute an endorsement by CEN of this (these) product(s). ↑

2. Replaced by EN ISO 4259:2006 and consequent revisions. ↑