🔬 Heavy metals in water — AAS
In short
Determination of heavy metals (Cu, Zn, Pb, Cd, Ni, Co) in water by flame atomic absorption spectrometry (FAAS). The test is performed according to PN-EN ISO 8288:2002; Linear range: 0.01–5 mg/L (depending on element). The procedure comprises 8 steps (about 1 h 31 min–2 h 2 min in total); it is used for: Drinking water quality control — heavy metals (Journal of Laws 2017, item 2294), Monitoring of surface and groundwater, Analysis of industrial wastewater (electroplating, metallurgy).
At a glance
- Standard: PN-EN ISO 8288:2002
- Category: Physicochemistry
- Procedure steps: 8
- Total time of stages: 1 h 31 min–2 h 2 min
- Limit of quantification Cu: 0.01 mg/L (FAAS)
- Limit of quantification Zn: 0.005 mg/L (FAAS)
- Limit of quantification Pb: 0.05 mg/L (FAAS)
Overview
Atomic absorption spectrometry (AAS) is one of the most widely used techniques for determining heavy metals in water samples. The PN-EN ISO 8288 standard specifies methods for determining cobalt, nickel, copper, zinc, cadmium, and lead in drinking water, surface water, groundwater, and wastewater using flame AAS (FAAS).
Heavy metals pose serious threats to human health and the environment. Lead causes neurological damage, cadmium is carcinogenic, and excess copper and zinc are toxic to aquatic organisms. Monitoring these metals is required by the Polish Minister of Health Regulation on drinking water quality (Journal of Laws 2017, item 2294) and EU Directive 2020/2184/EU.
FAAS is a relatively simple, fast, and cost-effective technique offering high accuracy and sensitivity at the ppb (parts per billion) level. Each element requires a separate hollow cathode lamp (HCL) emitting characteristic radiation.
Method principle
The method is based on the absorption of electromagnetic radiation by free atoms in the gaseous state. The sample in solution form is aspirated through a nebulizer into an acetylene-air (or acetylene-nitrous oxide) flame, where atomization occurs — decomposition of chemical compounds into free atoms.
Monochromatic radiation from a hollow cathode lamp (HCL) specific to the element being determined passes through the flame. Free atoms in the flame absorb radiation at a wavelength characteristic of the given element. The detector measures the attenuation of the radiation beam, and absorbance is proportional to the concentration of the metal being determined in the sample (Beer-Lambert law).
For each element, an optimal wavelength is used: Cu — 324.8 nm, Zn — 213.9 nm, Pb — 217.0 nm, Cd — 228.8 nm, Ni — 232.0 nm, Co — 240.7 nm.
Applications
- Drinking water quality control — heavy metals (Journal of Laws 2017, item 2294)
- Monitoring of surface and groundwater
- Analysis of industrial wastewater (electroplating, metallurgy)
- Control of municipal wastewater (water permits)
- Geochemical studies of groundwater
- Landfill monitoring (leachate)
Key parameters
| Parameter | Value |
|---|---|
| Limit of quantification Cu | 0.01 mg/L (FAAS) |
| Limit of quantification Zn | 0.005 mg/L (FAAS) |
| Limit of quantification Pb | 0.05 mg/L (FAAS) |
| Limit of quantification Cd | 0.005 mg/L (FAAS) |
| Limit of quantification Ni | 0.02 mg/L (FAAS) |
| Linear range | 0.01–5 mg/L (depending on element) |
| Repeatability | RSD < 2–5% |
Standard
- Standard number
- PN-EN ISO 8288:2002
- Title (PL)
- Jakość wody — Oznaczanie kobaltu, niklu, miedzi, cynku, kadmu i ołowiu — Metody płomieniowej absorpcyjnej spektrometrii atomowej
- Title (EN)
- Water quality — Determination of cobalt, nickel, copper, zinc, cadmium and lead — Flame atomic absorption spectrometric methods
Step-by-step procedure
-
Sample preparation
Acidify water sample immediately after sampling — add 1 mL concentrated HNO₃ per 100 mL sample. pH < 2. Store in PE/PP containers.
-
Digestion (if required)
For turbid samples or wastewater: acid digestion in open system (HNO₃ + HCl) or microwave (closed). Heat until clear solution is obtained.
-
Preparation of standard solutions
Prepare series of calibration solutions from certified standard solutions (e.g., 0; 0.1; 0.5; 1.0; 2.0 mg/L). Acid matrix identical to samples.
-
Setting spectrometer parameters
Install appropriate HCL lamp. Set wavelength, slit width, gas flows. Adjust burner position. Lamp warm-up time 10–15 min.
-
Instrument calibration
Measure series of calibration standards. Verify linearity of curve (R² > 0.999). Check sensitivity (characteristic absorbance).
-
Sample measurement
Aspirate samples into flame. Read absorbance. Between samples aspirate rinse solution (2% HNO₃). Blank sample every 10 samples.
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Quality control
Every 10 samples measure reference material (CRM) and control solution. Recovery 90–110%. Duplicate every 20 samples — RPD < 10%.
-
Calculations and reporting
Read concentration from calibration curve. Account for dilution, sample volume. Result in mg/L with measurement uncertainty.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Flame AAS spectrometer | Agilent 280FS AA, Shimadzu AA-7800, Thermo iCE 3500 | 80 000–250 000 PLN |
| Hollow cathode lamps (HCL) | Agilent, Heraeus, Photron — separate lamp for each element | 800–1 500 PLN/pc |
| Nebulizer and spray chamber | Standard set for FAAS (glass pneumatic nebulizer) | included with spectrometer |
| Acetylene cylinder | Dissolved acetylene, purity 2.6 | 200–400 PLN/cylinder |
| Air compressor | JUN-AIR or oil-free laboratory compressors | 5 000–15 000 PLN |
| Autosampler (optional) | Agilent SPS 4, Shimadzu ASC-7000 | 30 000–60 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Concentrated nitric acid (HNO₃) | 7697-37-2 | Suprapur/Ultrapur purity, for acidification and digestion of samples, 65% |
| Hydrochloric acid (HCl) | 7647-01-0 | Suprapur purity, for preparation of standard solutions, 30–37% |
| Metal standard solutions (1000 mg/L) | various | Certified CRM: Cu, Zn, Pb, Cd, Ni, Co — traceability to NIST/BAM |
| Ultrapure water | — | Type I according to ASTM, resistivity >18.2 MΩ·cm (Milli-Q or Hydrolab system) |
| Rinse solutions | — | 2% HNO₃ for rinsing sample introduction system |
Health and safety (OHS)
- Concentrated nitric acid — highly corrosive, causes burns. Nitrile gloves, goggles, fume hood
- Acetylene — flammable and explosive gas. Check gas installation tightness
- Heavy metal solutions (Pb, Cd) — toxic, collect as hazardous waste
- AAS flame — temperature ~2300°C, burn risk. Keep combustible materials away
- Lab coat, safety goggles and gloves mandatory
- Ventilation — exhaust above burner must be on during operation
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN ISO 8288:2002 — “Water quality — Determination of cobalt, nickel, copper, zinc, cadmium and lead — Flame atomic absorption spectrometric methods”.
How does this method work?
The method is based on the absorption of electromagnetic radiation by free atoms in the gaseous state. The sample in solution form is aspirated through a nebulizer into an acetylene-air (or acetylene-nitrous oxide) flame, where atomization occurs — decomposition of chemical compounds into free atoms.
What is the measuring range and accuracy?
Limit of quantification Cu: 0.01 mg/L (FAAS); Limit of quantification Zn: 0.005 mg/L (FAAS); Limit of quantification Pb: 0.05 mg/L (FAAS); Limit of quantification Cd: 0.005 mg/L (FAAS).
How long does the test take?
The times given for the individual stages add up to approximately 1 h 31 min–2 h 2 min. The procedure comprises 8 steps.
What equipment is required?
Flame AAS spectrometer, Hollow cathode lamps (HCL), Nebulizer and spray chamber, Acetylene cylinder, Air compressor, Autosampler (optional). Indicative cost of the core instrument (Flame AAS spectrometer): 80 000–250 000 PLN.
Where is this test used?
Drinking water quality control — heavy metals (Journal of Laws 2017, item 2294); Monitoring of surface and groundwater; Analysis of industrial wastewater (electroplating, metallurgy); Control of municipal wastewater (water permits); Geochemical studies of groundwater; Landfill monitoring (leachate).
What safety precautions apply?
Concentrated nitric acid — highly corrosive, causes burns. Nitrile gloves, goggles, fume hood; Acetylene — flammable and explosive gas. Check gas installation tightness; Heavy metal solutions (Pb, Cd) — toxic, collect as hazardous waste; AAS flame — temperature ~2300°C, burn risk. Keep combustible materials away; Lab coat, safety goggles and gloves mandatory; Ventilation — exhaust above burner must be on during operation.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN ISO 8288.