⚗️ Determination of nicotine, propylene glycol and glycerol in liquids for electronic cigarettes (e-liquids) by gas chromatography with flame ionization detection — 0,1 g of sample diluted with 10 ml of isopropanol containing an internal standard (quinaldine, 1,3-butanediol, n-heptadecane or n-octadecane), capillary column (e.g. DB-ALC1), at least five calibration solutions, linear regression not forced through zero, result in mg/g with three significant figures, PN-EN ISO 20714

Physicochemistry PN-EN ISO 20714

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 20714:2022-05 (English version; scope in Polish on the card), in full (our translation): “This document describes an analytical method for the quantitative determination of nicotine, propylene glycol and glycerol in e-liquids by gas chromatography.” We read the text of the standard in the ISO 20714:2019 preview IN FULL (Clauses 1–11 with Table 1).

ACCORDING TO THE TEXT OF ISO 20714:2019. The standard was prepared by ISO/TC 126/SC 3 (vape and vapour products). There are no normative references (2). Definitions (3): e-liquid — liquid or gel consumable, with or without nicotine, intended for transformation into an aerosol and inhalation with an electronic nicotine delivery device; electronic nicotine delivery device — transforms an e-liquid into an inhalable aerosol. Principle (4): the sample is diluted with isopropanol containing internal standard(s) and analysed by capillary gas chromatography with flame ionization detection (GC-FID), quantified with the internal standard. Reagents (5): carrier gas — helium or hydrogen of high purity; hydrogen and air for the detector; isopropanol of at least 99 % purity; high-purity internal standards — quinaldine, 1,3-butanediol, n-heptadecane, n-octadecane (anethole and others — after assessment of purity and checking that they do not co-elute; the peak area of the internal standard in samples is monitored, and in case of inconsistency a sample without the internal standard is analysed to exclude a peak at the same time); dilution solution, e.g. 0,2 mg/ml quinaldine or 1 mg/ml 1,3-butanediol, n-heptadecane or n-octadecane in isopropanol; reference substances — nicotine of known purity of at least 98 % (or nicotine salicylate ≥ 98 %, purity can be verified according to ISO 13276), propylene glycol and glycerol of at least 99 % purity; at least five calibration solutions in the dilution solution covering the expected range (linear ranges in the collaborative study: nicotine 0,005–1,5 mg/ml, propylene glycol and glycerol 0,12–10 mg/ml), stored at 2–8 °C in the dark and brought to room temperature before use. Apparatus (6): gas chromatograph with FID; capillary column — DB-ALC1 (30 m × 0,32 mm, 1,8 µm film) has been found satisfactory, others (e.g. WAX) — if the peaks of solvent, internal standards, nicotine, propylene glycol, glycerol and other components are well resolved. Sampling (7): according to a suitable procedure. Procedure (8): bring the sample to room temperature before opening; weigh 0,1 g to the nearest 0,001 g, pipette 10 ml of dilution solution, seal immediately and mix, transfer to a vial; analyse as soon as possible, and if storage is inevitable keep at 2–8 °C in the dark. Example conditions for DB-ALC1: 100 °C for 1 min, 15 °C/min to 130 °C, 40 °C/min to 220 °C, 10 min; injector 250 °C, detector 275 °C; 1 µl, split 50:1; helium 1,8 ml/min, air 450 ml/min, hydrogen 40 ml/min; once optimized the same conditions for all standards and samples (note: a ramp of 5 °C/min instead of 40 °C/min or a DB-Wax column improves separation). Calibration (8.3): 1 µl of each solution, ratios of analyte peak areas to the internal standard, linear regression NOT forced through the origin; a calibration solution periodically in the sequence as a check. Calculation (9): w = c × V / m (mg/g), c — concentration from the curve (mg/ml), V — volume of dilution solution (normally 10 ml), m — mass of sample (g). Precision (10): collaborative study of 19 laboratories on 7 e-liquids of different content and flavours; r and R exceeded on average not more than once in 20 cases. Table 1 — nicotine: means 10,02; 9,92; 4,97; 5,62; 2,77; 15,12; 32,92 mg/g, r from 0,27 to 2,33 mg/g, R from 0,89 to 5,54 mg/g; propylene glycol: means from 178,4 to 862,1 mg/g, r from 9,0 to 46,5 mg/g, R from 23,5 to 90,5 mg/g; glycerol: means from 98,8 to 782,5 mg/g, r from 6,7 to 64,0 mg/g, R from 17,4 to 123,2 mg/g. Test report (11): nicotine, propylene glycol and glycerol content in mg/g (three significant figures), sampling method, method used, conditions that may affect the result.

STATUS (PKN catalogue cards as of 02.10.2026). The card of PN-EN ISO 20714:2022-05 (English version, published 31-05-2022, 18 pages, price group J) has no “Withdrawn” header: Food, Agriculture and Forestry Sector, KT 321 Electronic Nicotine Inhalers and Refill Liquids, ICS 65.160, “Introduces: EN ISO 20714:2021 [IDT], ISO 20714:2019 [IDT]”. The PKN search for “PN-EN ISO 20714” (02.10.2026) shows only this standard. The EVS catalogue (read 02.10.2026) lists ISO 20714:2019 as valid from 05.08.2019.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 02.10.2026). The number 20714 appears in 10 records at 7 laboratories: AB 411, AB 826, AB 907, AB 1488, AB 1745, AB 1755, AB 1758. In the current scopes on the PCA website (read 02.10.2026, issues from 19.09.2025 to 31.08.2026): “PN-EN ISO 20714:2022-05” is given by AB 411, AB 826, AB 907 and AB 1758; “ISO 20714:2019” together with “PN-EN ISO 20714:2022-05” — by AB 1488; only “ISO 20714:2019” — by AB 1745 and AB 1755 (AB 1755 also “ISO 20714” without a year). The “Laboratories” tab searches for entries STARTING WITH “PN-EN ISO 20714” and shows 4 laboratories (AB 411, AB 826, AB 907, AB 1758); the other three have entries starting with “ISO 20714” in the database, so they do not appear in this tab — checked with the tab query on the production server labcoda.pl on 02.10.2026.

WHAT THE LABORATORIES TEST (PCA entries). All — GC-FID. Nicotine only: e-cigarette liquids from 5,0 to 32,0 mg/g and from 5,1 to 41,0 mg/ml, next to an in-house procedure (AB 411); from 3,75 to 150,00 mg/g (AB 826); from 0,471 to 21,6 mg/g and “(0,555 – 25,4) mg/l” (as in the PCA document), next to an in-house procedure (AB 907); from 2,77 to 32,92 mg/g (AB 1758). Nicotine, propylene glycol and glycerol: “Tobacco products: nicotine liquid” — nicotine from 2 to 40 mg/ml and from 0,5 to 200 mg/g, glycerol and glycol from 100 to 1000 mg/ml and mg/g (AB 1488); nicotine from 2,00 to 40,0 mg/ml, glycerine and glycol from 100 to 1000 mg/ml (AB 1745); refill liquids in a flexible scope — nicotine, glycol, glycerine (AB 1755). AB 1755 also has an entry “Nicotine pouches — nicotine content from 3,00 to 20,0 mg/g” with ISO 20714:2019.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Test item: the standard concerns e-liquids — nicotine pouches (AB 1755) lie outside the scope of the standard, and its precision data come exclusively from e-liquids. Internal standard: a component of the liquid eluting at the time of the internal standard can increase its peak and thereby lower the results calculated from area ratios — the standard requires monitoring the internal standard peak area and, in case of inconsistency, analysing the sample without the internal standard. Calibration: the regression is not forced through zero; calibration solutions must cover the expected range — the linear ranges from the collaborative study (nicotine up to 1,5 mg/ml in solution, i.e. approx. 150 mg/g for 0,1 g in 10 ml) are not limits of the standard. Units: the result of the standard is in mg/g — conversion to mg/ml requires the density of the liquid, which the standard does not determine; the entry “mg/l” at AB 907 does not correspond to the units of the standard. Precision: the r and R limits depend on the level — for nicotine from 0,27 to 2,33 mg/g (r), so there is no single precision figure; the AB 1758 range from 2,77 to 32,92 mg/g coincides exactly with the lowest and highest mean of Table 1.

WHAT WE DO NOT STATE. We have the full text of the standard. We give no limits of quantification or detection — the standard does not specify them; nor do we give a sampling procedure (the standard refers to “a suitable procedure”).

Method principle

0,1 g of e-liquid is diluted with 10 ml of isopropanol containing an internal standard and analysed by GC-FID on a capillary column; the ratios of the peak areas of nicotine, propylene glycol and glycerol to the internal standard are converted with a linear calibration curve to mg/ml and then to mg/g of liquid (w = c·V/m).

Applications

• Liquids for electronic cigarettes (e-liquids) — nicotine, propylene glycol, glycerol; 7 laboratories in PCA scopes
• Checking the declared nicotine content of refill liquids
• Testing the composition of the carrier (propylene glycol, glycerol) in e-liquids

Key parameters

Standard

Standard number

PN-EN ISO 20714:2022-05 (wersja angielska; EN ISO 20714:2021 IDT, ISO 20714:2019 IDT)

Title (PL)

E-liquid — Oznaczanie zawartości nikotyny, glikolu propylenowego i gliceryny w płynach do uzupełniania papierosów elektronicznych — Metoda chromatografii gazowej

Title (EN)

E-liquid — Determination of nicotine, propylene glycol and glycerol in liquids used in electronic nicotine delivery devices — Gas chromatographic method

Step-by-step procedure

1. Solutions

   Dilution solution (isopropanol + internal standard); ≥ 5 calibration solutions of nicotine, glycol and glycerol; storage at 2–8 °C in the dark. PN-EN ISO 20714:2022-05 current (PKN cards as of 02.10.2026).

2. Sample

   Bring to room temperature before opening; 0,1 g (± 0,001 g) + 10 ml dilution solution, seal immediately, mix, transfer to a vial.

3. Chromatograph

   Conditions chosen so that the peaks of isopropanol, internal standard, nicotine, glycol, glycerol and other components are resolved; once optimized, unchanged for standards and samples.

4. Calibration and analysis

   1 µl each of calibration solutions and sample; area ratios to the internal standard; linear regression not forced through zero; check solution periodically in the sequence.

5. Result

   w = c × V / m in mg/g, three significant figures; repeatability assessment according to Table 1.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Nicotine is highly toxic, and isopropanol and hydrogen are flammable — the standard contains no safety warnings; the laboratory sets the handling rules according to the safety data sheets
• TECHNICAL NOTE: result in mg/g; monitor the internal standard peak (co-elution of flavour components); the standard covers e-liquids, not other nicotine products

Frequently asked questions