prEN 16423

• Abstract:

  This European Standard specifies a method for the determination of the dissolved residual matter, also known as evaporation residue, in liquefied petroleum gases (LPG), by gas chromatography in the range of (10 to 600) mg/kg (ppm mass). ; This test method quantifies soluble organic compounds (hydrocarbon materials), sometimes called ‘evaporation residue’, which can be present in liquefied petroleum gases and which are substantially less volatile than the LPG product, i.e. with a boiling point between 174 °C and 522 °C (C10 to C40). Higher boiling materials, or materials that adhere permanently to the chromatographic column, will not be detected. ; WARNING - 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.

• Status: Not Published
• Publication Date: 22-Dec-2027
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Drafting Committee: CEN/TC 19/WG 23 - Specification of automotive LPG and related test method
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 10-Sep-2026
• Due Date: 10-Sep-2026
• Completion Date: 10-Sep-2026
• Ref Project: oSIST prEN 16423:2026 - Liquefied petroleum gases - Determination of dissolved residue - Gas chromatographic method using liquid, on-column injection

• Revises: EN 16423:2013 - Liquefied petroleum gases - Determination of dissolved residue - Gas chromatographic method using liquid, on-column injection
• Effective Date: 22-Oct-2025

prEN 16423 is a draft European Standard from CEN for determining dissolved residue, also called evaporation residue, in liquefied petroleum gases (LPG). It specifies a gas chromatographic method using liquid, on-column injection for soluble organic compounds in LPG in the range of 10 mg/kg to 600 mg/kg, and it is aimed at laboratories and other users who need a measured residue value for product control.

What does prEN 16423 specify?

prEN 16423 specifies a laboratory test method for dissolved residual matter in LPG by gas chromatography (GC). The method is intended for soluble organic compounds that are much less volatile than the LPG itself, roughly in the C10 to C40 boiling range, and it uses liquid, on-column injection so the sample stays in the liquid phase during injection.

The document is organized as a full test method. It covers scope, normative references, terms and definitions, principle, reagents and materials, apparatus, sampling, preparation of apparatus, test procedure, calculations, quality control, expression of results, precision, and test report.

Annex	What it covers
Annex A	Density calculation of the LPG and correction of the result
Annex B	Quality control monitoring
Annex C	Analysis of benzene, toluene and hydrocarbons C7 through C10
Annex D	Analysis of di-iso-propanolamine
Annex E	FID linearity check

The scope also makes clear what the method is meant to capture in practice: contamination that can enter LPG during production, transportation, or storage, and that is still detectable by GC under the method conditions.

What are the key requirements of prEN 16423?

prEN 16423 is built around a GC procedure that measures a small LPG aliquot, separates the residue on a column system, and quantifies it by an external standard. In practice, the reader needs to control sampling, injection, calibration, blank subtraction, and result correction carefully, because the result depends on both chromatographic behavior and sample density.

Sample handling and sampling

Clause 7 points users to EN ISO 4257:2001/AC for sampling unless commodity specifications or national rules say otherwise. This matters because the test result only represents the LPG sample if the sample was taken correctly and kept representative.

Apparatus and injection system

Clauses 6 and 8 require a GC with a large volume cold on-column injector, temperature-programmed oven, flame ionisation detector (FID), solvent vent, retention gap, pre-column, analytical column, column splitter, high pressure liquefied gas injector, and pressure station. In practice, this means the method depends on equipment that can keep LPG in liquid phase until it reaches the column and can vent the light matrix components before the residue is measured.

Calibration and validation

Clause 9.3 uses a one-point calibration at installation, after validation failures, and after relevant hardware or gas-supply changes. The method also requires a validation sample and a stable baseline before routine work, which matters because the instrument must be checked before results are accepted.

Test procedure and duplicate analysis

Clause 9.4 requires the sample cylinder to be pressurised, flushed, injected, and analysed in duplicate. If the duplicate results differ by more than 5 %, an extra analysis is made and the two closest results are averaged. This gives the user a practical repeat check on injection consistency and chromatographic stability.

Integration and quantification range

Clauses 9.2 and 10 require subtraction of the blank and integration of the residue area from C10 through C40. The method sums the area corresponding to the expected boiling range, so the user is not counting the LPG matrix itself, only the heavier residue fraction.

Density correction

Clause 10 and Annex A require correction when the calibration material and sample have different densities. Annex A explains how to calculate LPG density from composition, including conversion between mole fraction and mass fraction and use of EN ISO 8973. This matters because the injected mass changes with density, so the final mg/kg result needs correction when the sample and calibration matrix are not equivalent.

Quality control, precision, and reporting

Clause 11 requires validation samples after calibration and at least once when samples are analysed, while Annex B gives guidance for QC monitoring and control charts. Clause 13 gives repeatability and reproducibility statements derived from interlaboratory data, and Clause 14 requires the report to identify the standard used, the product, the result, any deviations, and the test date.

Annex C and Annex D extend the practical use of the method to specific contaminants: benzene, toluene, C7 to C10 hydrocarbons, and di-iso-propanolamine. Annex E provides a linearity check for the FID, which is useful after installation or major repair.

What terms does prEN 16423 define?

prEN 16423 uses several technical terms that shape how the method is applied.

• Dissolved residual matter / evaporation residue - soluble organic material in LPG that is less volatile than the LPG and is measured by the method.
• High pressure liquefied gas injector - a sample introduction device that injects LPG under pressure and at room temperature so the sample remains liquid during injection.
• Pressure station - a device that supplies high-pressure inert gas to the sample cylinder and helps keep the sample in liquid phase.
• Validation sample - a check sample used to confirm that the method is performing within acceptable limits.
• Quality control (QC) sample - a control material used to monitor ongoing performance of the instrument or test process.
• Response factor - the factor calculated from a calibration mixture and used to convert chromatographic area into dissolved residue content.
• Repeatability - the closeness of two results from the same laboratory under the same conditions over a short time.
• Reproducibility - the closeness of results from different laboratories under varying normal conditions.

Who uses prEN 16423?

prEN 16423 is used by laboratories that test LPG for residue content, especially where product quality or contamination tracing matters. The introduction links it to LPG end-use applications and to contamination arising during production, transportation, or storage.

Typical users include:

• LPG producers and suppliers
• quality control laboratories
• contract and third-party testing laboratories
• regulatory or conformity assessment laboratories
• buyers checking delivered product quality

The method is relevant when users need more than a simple residue number. It also gives a chromatographic fingerprint and boiling-range information, which can help trace the source of contamination.

What changed in prEN 16423 from the previous edition?

prEN 16423 will supersede EN 16423:2013. The foreword lists these significant changes:

• refreshed chromatograms
• clarification of the use of blank subtraction
• addition of calculation factors for DME
• addition of an informative Annex F presenting a faster and extended methodology

Which standards are used with prEN 16423?

prEN 16423 cites several standards that support the method or its data treatment.

• ISO 1998-1 - provides petroleum terminology used in the document.
• EN 589 - gives the LPG requirements context and is cited for terms and application context.
• EN ISO 4257:2001/AC - provides the sampling method for LPG.
• EN ISO 8973:1999/A1 - supports density calculation and mass-fraction conversion in Annex A.
• EN 27941 - is used in Annex A as a basis for LPG composition analysis when density is calculated from composition.
• EN ISO 4259:2006 and ASTM D 6300 - support the precision analysis behind Clause 13.
• EN ISO 4259-4 and ASTM D 6299 - support QC monitoring and control charting in Annex B.

What does the prEN 16423 document contain?

prEN 16423 contains a complete chromatographic test method, not just a principle statement. It includes equipment layouts, operating conditions, calibration steps, blank handling, duplicate analysis rules, density correction formulas, and reporting requirements.

The document also contains:

• Figure 1 to Figure 3 for column and pressure-station configurations
• Figure 4 and Figure 5 for chromatogram examples
• Table 1 for typical operating conditions
• Table 2 for repeatability and reproducibility examples
• Annex A calculation steps and worked density correction example
• Annex C and Annex D application examples for specific contaminants
• Annex E procedure for checking FID linearity

In practice, that means the document supports method setup, routine testing, troubleshooting, quality control, and result reporting for LPG residue analysis.

SLOVENSKI STANDARD
01-september-2026
Utekočinjeni naftni plini - Določanje raztopljenega ostanka - Metoda plinske
kromatografije z injiciranjem tekočine v kolono
Liquefied petroleum gases - Determination of dissolved residue - Gas chromatographic
method using liquid, on-column injection
Flüssiggas - Bestimmung gelöster Rückstände - Gaschromatographisches Prüfverfahren
durch Direkteinspritzung von Flüssigkeit auf die Säule
Gaz de pétrole liquéfié - Détermination des résidus dissous - Méthode par
chromatographie en phase gazeuse avec injection liquide on-column
Ta slovenski standard je istoveten z: prEN 16423
ICS:
75.160.20 Tekoča goriva Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2026
ICS Will supersede EN 16423:2013
English Version
Liquefied petroleum gases - Determination of dissolved
residue - Gas chromatographic method using liquid, on-
column injection
Gaz de pétrole liquéfié - Détermination des résidus Flüssiggas - Bestimmung gelöster Rückstände -
dissous - Méthode par chromatographie en phase Gaschromatographisches Prüfverfahren durch
gazeuse avec injection liquide on-column Direkteinspritzung von Flüssigkeit auf die Säule
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 19.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16423:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Reagents and materials . 6
5.1.1 Mineral oil in LPG calibration mixture . 6
5.1.2 Mineral oil in pentane calibration mixture. . 6
5.1.3 Mineral oil or local hydrocarbon fraction, boiling point range approximately C
to C . . 6
6 Apparatus . 6
7 Sampling . 10
8 Preparation of apparatus . 10
9 Test procedure . 11
9.1 Safety and hazards . 11
9.2 Summary of the method . 11
9.3 Calibration . 12
9.4 Procedure . 13
10 Calculations . 13
11 Quality control . 14
12 Expression of results . 15
13 Precision . 15
13.1 General . 15
13.2 Repeatability . 15
13.3 Reproducibility . 15
14 Test report . 15
Annex A (normative) Density calculation of the LPG and correction of the result . 17
A.1 General . 17
A.2 Inter conversion to LPG mass fraction according to EN ISO 8973 . 17
A.3 Density calculation according to EN ISO 8973 . 17
A.4 Example of a calculation . 18
Annex B (informative) Quality control monitoring . 20
Annex C (informative) Analysis of benzene, toluene and hydrocarbons C through C . 21
7 10
Annex D (informative) Analysis of di-iso-propanolamine . 23
Annex E (informative) FID linearity check . 24
Bibliography . 25
European foreword
This document (prEN 16423:2026) 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 16423:2013.
- Refreshed chromatograms
- Clarification of the use of blank subtraction
- Addition of the calculation factors for DME
- Addition of an informative Annex F that presents a faster and extended methodology
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
Introduction
Control over the residue content as spécifiéd in is of EN 589 [1] considerable importance in end-use
applications of Liquéfiéd Petroleum Gas (LPG). Dissolved residual matter, also known as evaporation
residue, in LPG is contamination which can occur during production, transportation or storage.
This standard has been developed as a potential replacement of the commonly used methods, as this
method of determination:
— is quicker and much more sensitive than manual methods, such as ASTM D 2158 [2] or EN 15471
[3], which are based on evaporation of (large) sample volumes followed by visual or gravimetric
estimation of residue content;
— provides enhanced sensitivity in measurements of heavier (evaporation) residues compared to
EN 15470 [4], with a quantification limit of 10 mg/kg total residue;
— gives both quantitative results and information about contaminant composition such as boiling
point range and fingérprint, which can be very useful in tracing the source of a particular
contaminant.
1 Scope
This document spécifiés a method for the determination of the dissolved residual matter, also known
as evaporation residue, in liquéfiéd petroleum gases (LPG), by gas chromatography in the range of (10
to 600) mg/kg (ppm mass).
This test method quantifiés soluble organic compounds (hydrocarbon materials), sometimes called
‘evaporation residue’, which can be present in liquéfiéd petroleum gases and which are substantially
less volatile than the LPG product, i.e. with a boiling point between 174 °C and 522 °C (C to C ). Higher
10 40
boiling materials, or materials that adhere permanently to the chromatographic column, will not be
detected.
WARNING This document 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 document to establish appropriate safety and health
practices and determine the applicability of regulatory limitations prior to use.
2 Normative references
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.
ISO 1998-1, Petroleum industry — Terminology — Part 1: Raw materials and products
EN 589, Automotive fuels - LPG - Requirements and test methods
EN ISO 4257:2001/AC, Liquefied petroleum gases - Method of sampling (ISO 4257:2001/Cor.1:2007)
3 Terms and definitions
For the purposes of this document, the following terms and définitions apply/ the terms and définitions
given in EN 589, ISO 1998-1 and the following apply.
— ISO Online browsing platform: available athttp://www.iso.org/obp
— IEC Electropedia: available athttp://www.electropedia.org/
3.1
high pressure liquefied gas injector
sample introduction device which injects liquéfiéd gas samples under pressure and at room temperature
directly onto the chromatographic column thereby maintaining the sample in liquid phase during the
injection process
3.2
pressure station
device that supplies high pressure inert gas to a suitable sample cylinder and therefore maintains sample
in the liquid phase during the injection procedure
4 Principle
A small quantity of LPG is directly transferred in liquid phase from the sample cylinder on to a GC column
using a high pressure liquéfiéd gas injector. The mixture is then analysed by capillary gas
chromatography and the dissolved residue content is quantifiéd by the external standard method.
5 Reagents and materials
IMPORTANT - Standards that are prepared in pentane, normally liquid at room temperature, shall be
stored under refrigeration and transferred to sample cylinders prior to use. Alternatively, they can be
stored in air tight cylinders
5.1 Mineral oil in LPG calibration mixture.
One of the following mixtures shall be selected for calibration:
5.1.1 Mineral oil in LPG calibration mixture
cértifiéd calibration mixture with about 50 mg/kg mineral oil in LPG.
5.1.2 Mineral oil in pentane calibration mixture.
Prepare a calibration standard of mineral oil in pentane. Record the exact weighed value to the nearest
mg of mineral oil and calculate the concentration in mg/kg. The concentration of the mineral oil shall
be close to the expected concentration of the contamination in the LPG sample.
5.1.3 Mineral oil or local hydrocarbon fraction, boiling point range approximately C to C .
10 40
Alternatively, a well characterised local hydrocarbon fraction, within the range C to C , can be used
10 40
to provide quantitative and qualitative comparison to the contaminant in the sample. Care should be
taken to ensure no more than 10% m/m% of the sample falls outside the C to C range.
10 40
5.2 Validation standard, mineral oil in pentane.
Prepare a validation standard of mineral oil in pentane. Record the exact weighed value to the nearest
mg of mineral oil and calculate the concentration in mg/kg. The concentration of the mineral oil shall
be close to the expected concentration of the contamination in the LPG sample.
5.3 n-Alkane retention time standard, mixture containing at least C and C in a concentration
10 40
of (nominally) 5 mg/l each, dissolved in pentane or heptane.
5.4 Solvent, GC grade pentane.
6 Apparatus
NOTE Successfully used columns and conditions are given in Table 1.
6.1 Gas chromatograph, equipped with a Large Volume Cold on Column Injector (LVOCI), linear
temperature programmable column oven, and a flamé ionisation detector (FID), with data acquisition
and processing system.
For checking the linearity of the FID one may use Annex E.
6.2 Solvent vent, controlled to allow venting the major part of the matrix.
6.3 Retention gap, uncoated stainless steel capillary.
6.4 Retaining pre-column, a column with a polydimethylsiloxane stationary phase.
6.5 Analytical column, a column with a polydimethylsiloxane stationary phase.
6.6 Column coupler, coupling device suitable for leak free coupling of the retention gap to the
retaining pre-column.
See Figure 1 for a schematic overview of the couplings inside the GC oven and the couplings to the
solvent vent valve.
Table 1 — Typical column configuration
Equipment part Typical operation conditions
35 °C for 3 min, 35 °C to 340 °C at 25 °C/min, 340 °C for
Oven program
10 min
Type: cool on-column
Inlet program
Temp: 55 °C for 3 min, 55 °C to 340 °C at 25 °C/min, 340
°C for 9 min
Air flow: 400 ml/min
Hydrogen flow: 40 ml/min
Detector settings Make up gas flow: 20 ml/min
Temperature: 350 °C
Data rate: 20 Hz
a
Retention gap: Sulfinért® ) stainless steel capillary
with inner diameter 0,53 mm and length of 5 m
Column
Retaining pre-column: 3 m HP-1, 0,53 mm, 2,65 µm
Analytical column: HP-1, 30 m, 0,32 mm, 0,25 µm
Sample flow: 2 ml/min
Pressure station Nitrogen pressure: 2 500 kPa
Nitrogen purge pressure: 500 kPa
Liquéfiéd gas injector Injection: 25 ms
a
Sulfinért ® is a stainless steel treatment system from Restek Co., 110 Benner Circle, Bellefonte, PA 16823,
USA. This information is given for the convenience of users of this European Standard and does not constitute
an endorsement by CEN of the product named. Equivalent products may be used if they can be shown to lead to
the same results.
6.7 Column splitter, suitable for leak-free coupling of the retaining pre-column to one side of the
analytical column and the deactivated capillary on the other side.
See Figure 1 for a schematic overview of the couplings inside the GC oven and the couplings to the
solvent vent valve.
Key
A solvent vent valve
B cool on-column inlet
C detector
D column splitter
E retention gap
F retaining pre-column
G analytical column
Figure 1 — Column overview
6.8 High pressure liquefied gas injector, a high pressure valve as in Figure 2, directly connected
to a needle which is inserted in the injection port of the GC, after which the valve is triggered in order
to introduce a representative aliquot into the GC system without sample discrimination.
Key
A eletrical attachment
B solenoid on
C valve spring
D spray tip
E pressurised fuel injection
F injector casing
G plunger
Figure 2
High pressure valve
6.9 Pressure station, ensuring a sample in liquid phase at a constant pressure, with a typical
configuration as in Figure 3 .
Key
A sample cylinder
B sample line in
C injection device
D cool on column inlet
E gas chromatograph
F sample line out
G rotometer
H vaporiser
I waste system
Figure 3 — Typical configuration of the pressure station
7 Sampling
Unless otherwise spécifiéd in the commodity spécification, samples shall be taken as described in
EN ISO 4257:2001/AC and/or in accordance with the requirements of national regulations for the
sampling of the product under test.
8 Preparation of apparatus
WARNING Take all the necessary safety measures and, in particular, earth the equipment in order to
eliminate the risks associated with static electricity.
8.1 Gas chromatograph: install and verify performance in accordance with the manufacturer’s
instructions. Typical operating conditions are shown in Table 1.
8.2 Pressure station: install in accordance with the manufacturer’s instructions. Purge sample and
check carefully for leaks. Connect the outlet to a waste system.
8.3 High pressure liquefied gas injector: install in accordance with the manufacturer’s
instructions.
8.4 Column configuration: install the columns as shown in Figure 1, using low dead volume
connections, and check for leaks.
9 Test procedure
9.1 Safety and hazards
9.1.1 There is a significant firé hazard from LPG, and since the boiling point of LPG can be as low as
-41 °C, there is a risk of freezing “burns”. Take appropriate safety precautions to prevent ignition or
firé, and wear suitable protective equipment to protect against skin contact with LPG.
9.1.2 An appropriate laboratory ventilation system shall be used.
9.1.3 An appropriate waste line shall be installed. The pressure station and injector shall be
connected to this line. The waste line shall exit outside the building. An appropriate waste facility shall
be available for liquid (pentane).
9.1.4 The pressure station, cylinder, injector and controller shall be grounded appropriately.
9.2 Summary of the method
a) A sample cylinder of LPG is pressurised on the pressure station to 2 500 kPa using nitrogen or
helium.
b) The injection system is flushéd with LPG in liquid phase at room temperature. The end of the
injection purge line is connected to a heated vaporiser which vaporises the LPG before transporting
it to a waste disposal system.
c) After flushing, the injection device is routed to the GC injector port and LPG (25 ms activation time
equivalent to 30 µl) is introduced via a high pressure valve and needle which is inserted into the
Cool On Column inlet.
d) The gas chromatograph is equipped with a solvent vent which routes most of the LPG light
components out of the analytical system and leaves behind the components of interest.
e) The dissolved residue to be determined is retained on the pre-column.
f) After venting, the light ends, the flow from the pre-column is switched to the analytical column and
a temperature program is started.
g) Dissolved residue contaminants are separated and
...