CEN/TC 19

Date:  2025-12

prEN 15199‑1:2026

CEN/TC 19

Secretariat:   NEN

Petroleum products — Determination of boiling range distribution by gas chromatography method — Part 1: Middle distillates and lubricating base oils

Mineralölerzeugnisse — Gaschromatographische Bestimmung des Siedeverlaufes — Teil 1: Mitteldestillate und Grundöle

Produits pétroliers — Détermination de la répartition dans l’intervalle de distillation par méthode de chromatographie en phase gazeuse — Partie 1 : Distillats moyens et huiles lubrifiantes

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 10

8 Preparation of the apparatus 10

8.1 Gas chromatograph preparation 10

8.2 System performance check 11

9 Sample preparation 11

10 Calibration 11

11 Procedure 13

12 Visual inspection of the chromatograms 14

13 Calculation 14

14 Expression of results 14

15 Precision 14

15.1 General 14

15.2 Repeatability 15

15.3 Reproducibility 15

16 Test report 16

Annex A (normative) Calculation procedure 17

Annex B (normative) System performance check 22

Annex C (normative) Boiling points of n-alkanes 24

Bibliography 25

European foreword

This document (prEN 15199‑1:2026) 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 15199‑1:2020.

The main changes in this edition are:

— the allowance of alternative carrier gasses (see 5.1 and 15.1);

— the alignment of the requirement regarding column resolution in the text and with ASTM D6352.

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) below 750 °C. For testing materials with initial boiling points (IBP) above 100 °C and final boiling point (FBP) above 750 °C, Part 2 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 can be used. Part 4 describes the determination of boiling range distribution of hydrocarbons up to n-nonane in crude oil.

This document is based on (and kept aligned with) IP Test Method IP 480 [4] and ASTM Test Method ASTM D6352 [3].

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 a boiling range of at least 100 °C. The document is applicable to distillates with initial boiling points (IBP) above 100 °C and final boiling points (FBP) below 750 °C, for example, middle distillates and lubricating base stocks.

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

Petroleum or petroleum products containing blending components which contain heteroatoms (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 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)

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 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

Key

Figure 1 — Typical chromatogram

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 obtained by running a mixture of known n-alkanes, covering the sample boiling range, under the same conditions. From these data, the boiling range distribution is obtained.

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

EN ISO 3924 [1] 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 15199‑2 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.

EN 15199‑3 is applicable to crude oils. The boiling range distribution and recovery (3.8) 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 [1] is also suitable.

5.5 Polyethylene wax solution^[1].

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

WARNING — Extremely flammable and toxic by inhalation.

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 of samples by comparing the total sample area (3.6) of the reference material with the total sample area (3.5) 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. A 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.

Key

Figure 2 — Typical chromatogram of binary gravimetric blend distillate

Table 1 — Reference material 5010

6.1 Gas chromatograph, with the following performance characteristics.

6.1.1 Flame ionization detector, connected to the column 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, 0,53 µm internal diameter coated with methyl silicone. Commercially available columns with film thickness (df) = 0,09 µm (for analysis up to C120) and (df) = 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 gas chromatograph (6.1) 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. 5 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 should 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.

Make a mass concentration of 2 % to 3 % solution of the sample in CS₂ (5.6). Transfer to an autosampler vial and immediately cap.

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 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.

Key

Figure 3 — Typical chromatogram of calibration mixture

Key

Figure 4 — Typical calibration curve

10.4 Run the Reference Material 5010 (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.

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.

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.

NOTE Users are encouraged to use in addition blank validation or rejection criteria proposed by simulated distillation software.

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 reference or sample, 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 sample baselines are merged. This is taken before the start of the sample and after the end of the solvent.

The end of the area of interest is taken at a point on the baseline where the blank and the sample baselines are merged. This is taken after the end of the sample and at or before the end of run.

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

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

Use the calculation protocol given in Annex A 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 99,5 % (m/m) point as the final boiling point (3.2);

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 [2] in a matrix of samples with properties in the range shown in Table 3, using helium as a carrier gas.

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 labs had used other gasses than helium. nitrogen or hydrogen are allowed as carrier gas, but the precision in this clause cannot be applied.

Table 3 — Range of results

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 4.

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 4.

Table 4 — Precision values

The test report shall specify at least:

a) a reference to this document and its year of publication, i.e. prEN 15199‑1:2026;

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 procedures specified;

e) any unusual features observed;

f) the date of the test.

1. 
   (normative)
   
   Calculation procedure
   1. Starting conditions
      1. Sample data array, N area slices

The data shall be collected at a minimum sampling frequency of 5 Hz to 10 Hz (slice width is 0,2 s to 0,1 s). In addition, the slice width shall be such that no sample or solvent elutes in the first 10 to 20 slices, respectively.

• • 1. Blank data array, N area slices

The slice width for the blank and sample runs shall be identical. A blank is not necessary if electronic baseline compensation is used (see Clause A.2).

The analysis conditions for blank and sample shall be identical through the point where sample analysis is terminated.

The number of slices in the blank array shall be equal to or greater than the number of slices in the sample chromatogram. If the number of slices in the blank array is greater than the number of slices in the sample array, then drop the extra slices in the blank array. This situation could occur if a blank run extended beyond the point where the sample analysis was terminated.

• • 1. Retention times of n-paraffins

The retention time of each n-paraffin in the calibration mixture shall be obtained from a processed (peak) data file from the analysis of the calibration mixture, run under identical conditions as the samples and blank.

• • 1. Boiling points of n-paraffins

The boiling point of each n-paraffin in the calibration mixture (to the nearest whole °C) should be obtained from Table C.1.

• • 1. Solvent exclusion time

The solvent exclusion time is that time when the signal has returned to baseline after elution of the solvent. This parameter is used to exclude area due to the solvent used, if any. If a solvent is used, the detector signal shall return to baseline before any sample components start to elute.

• 1. Subtraction of the blank from the sample

Subtract each blank area slice (3.3) from the exactly corresponding sample area slice. This corrects the sample area slice from the blank.

If the data was acquired on an instrument using automatic baseline compensation, this clause may be skipped. In this case, the zeroed sample data array contains the corrected area slices (3.4) to be used in subsequent calculations.

IMPORTANT — Automatic baseline compensation is available on many instruments and is allowed by this test method. However, automatic baseline compensation may not give the same results as slice-by-slice blank subtraction. On some instruments using automatic baseline compensation, the compensated baseline has been observed to exhibit an anomalous feature at or near the point in the chromatogram where the programmed oven temperature reaches maximum and is held for some period of time. The anomalous feature appears as a slow rise in baseline, followed by a relatively sharp decrease, followed by a level baseline. While the magnitudes of the anomalies observed have been very small (only a few picoamperes), the slope of the sharp decrease can be sufficient to meet the criterion for determining the end of sample elution. In such an event, this false triggering of the end of sample criterion will result in erroneously high values for the FBP. If false triggering occurs and cannot be eliminated, the user should disable automatic baseline compensation and perform blank subtractions as specified in this annex.

• 1. Zero data slices

A.3.1 Calculate the average of the first 10 to 20 (5 Hz to 10 Hz) area slices (3.3) of the blank-subtracted data array.

A.3.2 Subtract the average slice area (A.3.1) from each area slice (3.3) in the blank-subtracted data array. Set negative numbers to zero.

• 1. Total chromatogram area

A.4.1 Calculate the total sample area (3.6) by starting at the first slice (or the solvent exclusion time if a solvent is used), sum all of the area slices (3.3) through the last slice.

A.4.2 Designate this sum as the total chromatogram area (Atc).

• 1. Start of sample elution time

A.5.1 Start at the slice corresponding to the solvent exclusion time (or the first slice if no solvent was used) and work towards the end of the data array, determine where the rate of change per second between two consecutive slices first exceeds 0,000 01 % of the total chromatogram area (see A.4.2).

A.5.1.1 For determining the start of sample elution, the rate of change is calculated by subtracting the area of a slice from the area of the immediately following slice and dividing by the slice width (ws) in seconds.

A.5.1.2 If the requirement in Formula (A.1) is valid, with S_N being the area of the Nth slice, take slice N + 1 as the start of sample slice (see Clause A.2).

(A.1)

A.5.2 Report this retention time corresponding to the start of sample elution.

This may be done by printing the retention time and/or indicating it on the chromatogram.

• 1. End of sample elution time

A.6.1 Start at the last slice in the data array and working toward the start of sample, determine where the rate of change per second between two consecutive slices first exceeds 0,000 01 % of the total chromatogram area (see A.4.2).

A.6.1.1 For determining the end of sample elution, the rate of change is calculated by subtracting the area of a slice from the area of the immediately preceding slice and dividing by the slice width (ws) in seconds.

A.6.1.2 If the requirement in Formula (A.2) is valid, take slice N − 1 as the end of sample slice.

(A.2)

A.6.2 Report this retention time corresponding to the end of sample elution.

This may be done by printing the retention time and/or indicating it on the chromatogram.

Determination of the start and end of sample elution time is done by slope detection. As the slope can differ according to sample properties, the sensitivity levels can require adjustment, but this should not be done during an analysis. Where possible, the use of set start and end of sample elution times is recommended.

• 1. Total corrected sample area

A.7.1 Sum the corrected area slices (3.4) from the start of sample slice (A.5.1.2) to the end of sample slice (A.6.1.2).

A.7.2 Designate this sum as the total corrected sample area and save it for subsequent calculations.

• 1. Normalization to area percentage

A.8.1 Begin at the start of sample slice (A.5.1.2) and continue to the end of sample slice (A.6.1.2), divide each corrected area slice (3.4) by the total corrected sample area (A.7.2) and multiply by 100.

A.8.2 Record these normalized area percentages in an array for subsequent calculations.

• 1. Retention time corresponding 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 % (see A.9.4). 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 (see A.9.4). Use linear interpolation when the cumulative sum exceeds the percent being determined.

• • 1. Final boiling point

Find the retention time where the cumulative area percent is equal to, or greater than, 99,5 % (see A.9.4). Use linear interpolation to find the time corresponding to exactly 99,5 % of the total corrected sample area.

• • 1. Overall procedure

A.9.4.1 For each X, where X = 0,5, 1, 2, ..., 98 and 99,5, find the retention time corresponding to X percent off.

A.9.4.2 Begin with the start of sample slice and working toward the end of sample slice, determine the slice (designated N + 1 in the equations) at which the cumulative area percent first equals or exceeds X.

NOTE The cumulative area percent of a given slice is the sum of the normalized area percents from the start of sample slice through the given slice.

A.9.4.3 For the slice (N + 1) determined above, the following inequality should hold:

(A.3)

where

A.9.4.4 Calculate the fraction (f) of the (non-cumulative) normalized area percent (A) in slice (N + 1) needed to give exactly X percent off as follows:

(A.4)

A.9.4.5 The retention time corresponding to X percent off (RTX) is the retention time of the fractional slice (N + f) and is calculated as follows:

(A.5)

• 1. Conversion of retention times to boiling points

A.10.1 For each retention time determined in A.9.1 to A.9.4, calculate the boiling point equivalent to that retention time. Find the pair of calibration compound retention times that are closest to and bracket the percent off retention time of interest.

A.10.2 Calculate the boiling point corresponding to the percent off retention time, BPi, in °C, from the following Formula (A.6):

(A.6)

where

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

1. 
   (normative)
   
   System performance check
   1. Frequency

This procedure may be 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 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 and should have the following specifications for the gravimetric blend: 32,4 % ± 0,6 % (m/m) at 400 °C.

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

Bibliography

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

[2] 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)

[3] ASTM D6352, Standard test Method for Boiling Range Distribution of Petroleum Distillates in Boiling Range from 174 °C to 700 °C by Gas Chromatography

[4] IP 480, Petroleum products — Determination of boiling range distribution by gas chromatography method — Part 1: Middle distillates and lubricating base oils

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. ↑