🍎 Determination of lead, cadmium, zinc, copper and iron in foodstuffs by AAS after microwave digestion — portion corresponding to 0.2–0.5 g dry matter, usually 5 ml nitric acid (at least 65 %) and 2 ml hydrogen peroxide 30 % in a closed vessel (about 100 ml, at least 1.4 MPa), power programme according to the oven manufacturer, solution made up to at least 25 ml; Pb and Cd in a graphite furnace with platform (283.3 nm and 228.8 nm), Zn, Cu and Fe in an air–acetylene flame (213.9 nm, 324.7 nm, 248.3 nm), with background correction and usually the standard addition method; the method is not for oils, fats and very fatty products, PN-EN 14084

Food chemistry PN-EN 14084

Overview

WHAT THE STANDARD COVERS. The scope on the PKN catalogue card of PN-EN 14084:2004 (Polish version) (our translation): “Specifies a method for the determination of lead, cadmium, zinc, copper and iron in foodstuffs by atomic absorption spectrometry after microwave digestion, which cannot be applied to oils, fats and other products with a very high fat content”. We read the text of the standard in the iTeh sample of SIST EN 14084:2003 (text of EN 14084:2003, English): from the title page through the contents, foreword and Clauses 1–5 up to and including the whole of Clause 6 (digestion, dilution, flame and graphite furnace measurement). Outside the sample remain Clauses 7–9 (calculation, precision, test report) and Annex A (results of the interlaboratory test).

ACCORDING TO THE TEXT OF EN 14084:2003 (Clauses 1–6). The standard was prepared by CEN/TC 275 “Food analysis — Horizontal methods” (secretariat DIN); CEN approved it on 18.12.2002. Scope (1): lead, cadmium, zinc, copper and iron in foodstuffs by AAS after microwave digestion; the method is for various types of foodstuffs, but not for oils, fats and other very fatty products; the interlaboratory test with 16 participating laboratories covered composite diets, cereals, fish, beef, milk and fungi; foodstuffs for which specific (vertical) standards exist are excluded — checking this is the analyst’s task. Normative reference (2): EN 13804 (performance criteria, general considerations and sample preparation). Principle (3): digestion in closed vessels in a microwave oven with a mixture of nitric acid and hydrogen peroxide, dilution with water, measurement by flame or graphite furnace technique. Reagents (4): the content of trace elements in reagents and water low enough not to affect the result; nitric acid at least 65 % (ρ ≈ 1.4 g/ml), diluted about 0.1 mol/l (7 ml to 1000 ml) and about 3 mol/l (200 ml to 1000 ml); hydrogen peroxide 30 %; standard solutions 1000 mg/l from metals (examples of preparation, certified ones recommended); calibration solutions in 0.1 mol/l acid within the linear range. Apparatus (5): glassware and plastic ware cleaned according to EN 13804; AAS spectrometer with background correction, graphite furnace with autosampler, burners and gas supply; lamps (e.g. hollow cathode) for each element; pyrolytically coated graphite tubes with platform for Pb and Cd; laboratory microwave oven (power check according to EN 13804) and vessels of typically 100 ml withstanding at least 1.4 MPa; 100 ml plastic bottles. Digestion (6.2): a portion corresponding to 0.2–0.5 g dry matter or as recommended by the oven manufacturer (at 50 % water at most 1 g, at 95 % water 2 g); one reagent blank in every batch; typically 5 ml nitric acid and 2 ml hydrogen peroxide or as recommended by the manufacturer; power-versus-time programme according to the manufacturer — usually a few minutes at low power first, then one or more stages at higher power, with a gradual transition to avoid sudden pressure peaks; Table 1 gives an example for one oven model (250 W 3 min, 630 W 5 min, 500 W 22 min, 0 W 15 min); the programme is to be valid with the full number of vessels — missing ones may be treated as blanks; with pressure control in only one vessel, the one with the highest expected pressure is monitored, usually the one with the largest dry-matter intake; too large a portion of an unknown sample may rupture the safety membrane — especially samples high in carbon (sugar, fat, ethanol). Dilution (6.3): cool the vessels thoroughly before opening, rinse the lid and walls with water, make up to a definite volume of at least 25 ml in a plastic bottle; treat the blank in the same way. Measurement (6.4): the technique is chosen according to concentration — Pb and Cd in foodstuffs usually in the graphite furnace, Zn, Cu and Fe usually in the flame; background correction always, unless shown to be unnecessary; with the standard addition method — measurement in the linear range, at least three points (including at least two additions), the highest standard 3–5 times the sample concentration, the lower one half of the highest. Flame (6.4.2): the sample solution is diluted 1 + 1 with 0.1 mol/l acid, standard solutions 1 + 1 with 3 mol/l acid — standards and samples must have the same acid concentration, because high acidity harms results and the instrument; Zn and Cu usually against an ordinary calibration curve, Fe strongly affected by the matrix — standard addition or a matrix-matched curve, with severe interferences a nitrous oxide–acetylene flame; Table 2: oxidising air–acetylene flame, Zn 213.9 nm, Cu 324.7 nm, Fe 248.3 nm. Graphite furnace (6.4.3): technique usually required for Pb and Cd, also useful e.g. for Cu; injection volume such that the background absorbance does not exceed about 0.5; at very low concentrations — multiple injections; new matrices — ashing and atomisation curves; matrix modifiers may be used after validation in the laboratory; Table 3 (example for one instrument model, injection 20 µl): Pb 283.3 nm — drying 130 °C, ashing 450 °C, atomisation 1900 °C, cleaning 2500 °C; Cd 228.8 nm — 130, 350, 1200, 2500 °C; always the standard addition method unless shown to be unnecessary; simplification — a matrix-matched curve (standard addition curve shifted parallel to the origin) for samples of the same matrix and sample mass.

STATUS (cards as of 03.10.2026). The PKN card of PN-EN 14084:2004 (Polish version, published 28-09-2004, 18 pages, price group J) has no “Withdrawn” header: Food, Agriculture and Forestry Sector, KT 235 Food Analysis, ICS 67.050, “Introduces: EN 14084:2003 [IDT]”, “Replaces: PN-EN 14084:2003 — English version”. In the PKN search (term “PN-EN 14084”, 03.10.2026) the English version PN-EN 14084:2003 has the description “Withdrawn and replaced by PN-EN 14084:2004 — Polish version”; its title in the result list speaks of the determination of “lithium, cadmium, zinc, copper and iron” — in the EN text and in the Polish title it is lead, not lithium. In the iTeh catalogue (read on 03.10.2026) EN 14084:2003 has the status “Published”, stage 90.93 “Decision to confirm” (review from 17.09.2024, completed on 30.09.2026), committee CEN/TC 275 (working group WG 10 “Trace elements (heavy metals)”). The same elements and chromium after dry ashing are described in a separate entry on PN-EN 14082 (a standard withdrawn on 13.02.2020; “Determination of lead, cadmium, zinc, copper, iron and chromium in foodstuffs by AAS after dry ashing”), and arsenic, cadmium, mercury and lead by ICP-MS in a separate entry on PN-EN 15763.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read on 03.10.2026). The number 14084 appears in 6 records at 4 laboratories: AB 452, AB 538, AB 618, AB 1375. In the current PCA documents (read on 03.10.2026, issues from 30.10.2025 to 24.09.2026) the number appears in 6 items of the same 4 laboratories (AB 452 and AB 618 2 each — the number written once next to two adjacent items; AB 538 and AB 1375 1 each). The form is “PN-EN 14084:2004” everywhere and always as the only reference document in the item. None of these items is suspended. The “Laboratories” tab (“PN-EN 14084”) shows the same 4 laboratories — checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). AB 452 — fruit, vegetables and products, beverages, juices and concentrates, food concentrates, cereals and cereal products, raw materials and alcoholic products, raw materials and products of the sugar industry, herbs and spices, vitamin and mineral preparations: cadmium (0.020–1.00) and lead (0.020–3.00) mg/l or mg/kg by ETAAS and zinc (0.20–1000), iron (0.50–1500) and copper (0.20–100) mg/l or mg/kg by FAAS. AB 538 — foodstuffs of plant origin, copper (5.0–100.0) mg/kg by FAAS. AB 618 — among others coffee and tea, food concentrates, meat, milk, beverages, fruit and vegetables, fish and seafood, confectionery, herbs and spices, foodstuffs for particular nutritional uses, cereals, frozen foods, ready meals and food supplements: lead (0.025–2.0) mg/kg and cadmium (0.0025–5.0) mg/kg by ETAAS. AB 1375 — herbs, tea, confectionery, cereal products and milk powder: zinc (20–1000), copper (3–1000) and iron (40–1000) mg/kg by FAAS. The division of techniques in the scopes agrees with the standard: Pb and Cd in the graphite furnace, Zn, Cu and Fe in the flame.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the matrix: oils, fats and very fatty products are outside the scope (1), and samples high in sugar, fat or ethanol risk a sudden pressure peak and rupture of the membrane (6.2) — loss of part of the solution leaves no trace in the result. With acidity: standards and samples with different acid concentrations give a different flame signal for the same content (6.4.2). With iron: strong matrix effect — without standard addition or a matrix-matched curve the result is biased (6.4.2). With lead and cadmium: the standard requires the standard addition method always, unless shown to be unnecessary; a matrix-matched curve is valid only for samples of the same matrix and sample mass (6.4.3). With the oven programme: the programme is valid with the full number of vessels (6.2) — a different number of vessels without blanks in the free positions means different digestion conditions. With background: background correction is always used, unless shown to be unnecessary (6.4).

WHAT WE DO NOT GIVE. We did not read Clauses 7–9 and Annex A, so we do not give the calculation formula, precision data or interlaboratory test results. Nor do we give maximum levels of lead and cadmium in foodstuffs — we did not read the texts of regulations for this entry.

Method principle

A portion of food corresponding to 0.2–0.5 g dry matter is digested in a closed vessel in a laboratory microwave oven (usually 5 ml nitric acid and 2 ml hydrogen peroxide, power programme according to the oven manufacturer, with a gradual increase in power). After cooling, the solution is made up with water to at least 25 ml and measured by atomic absorption spectrometry with background correction: lead and cadmium usually in a graphite furnace with platform, by the standard addition method, and zinc, copper and iron in an air–acetylene flame, with the same acid concentration in standards and samples.

Applications

• Foodstuffs of various types — lead, cadmium, zinc, copper and iron; validation on composite diets, cereals, fish, beef, milk and fungi (1)
• Outside the scope: oils, fats, very fatty products and foodstuffs covered by specific standards (1)
• Fruit, vegetables, beverages, cereals, herbs, tea, coffee, meat, milk, fish, confectionery, food supplements — ETAAS (Pb, Cd) and FAAS (Zn, Cu, Fe) in the accreditation scopes of 4 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 14084:2004

Title (PL)

Artykuły żywnościowe — Oznaczanie pierwiastków śladowych — Oznaczanie zawartości ołowiu, kadmu, cynku, miedzi i żelaza metodą atomowej spektrometrii absorpcyjnej (AAS) po mineralizacji mikrofalowej

Title (EN)

Foodstuffs — Determination of trace elements — Determination of lead, cadmium, zinc, copper and iron by atomic absorption spectrometry (AAS) after microwave digestion

Step-by-step procedure

1. Sample

   Homogenisation according to EN 13804; if necessary drying without affecting the element content, e.g. freeze-drying. PN-EN 14084:2004 current (PKN card as of 03.10.2026).

2. Digestion

   Portion corresponding to 0.2–0.5 g dry matter, usually 5 ml HNO3 and 2 ml H2O2; closed vessel, power programme according to the oven manufacturer, full number of vessels; a blank in every batch.

3. Dilution

   Cool thoroughly before opening; rinse the lid and walls, make up with water to at least 25 ml in a plastic bottle.

4. Zn, Cu, Fe — flame

   Sample 1 + 1 with 0.1 mol/l acid, standards 1 + 1 with 3 mol/l acid; Fe by standard addition or a matrix-matched curve.

5. Pb, Cd — graphite furnace

   Tubes with platform, background correction, standard addition method (at least 3 points); we do not give the calculations.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Too large a portion of an unknown sample, especially one high in sugar, fat or ethanol, may rupture the safety membrane of the vessel (6.2)
• Pressure vessels are opened only after thorough cooling (6.3)
• The standard warns that its use may involve hazardous materials, operations and equipment, and that safety practices are established by the user (3)

Frequently asked questions