Major Ions

• Two proficiency testing items (samples) on different concentration levels
• Two bottles (2 x 500 mL) per proficiency testing item; (cooperation partner UBA, real water samples: additionally 250 mL for DOC per sample)
• Natural samples: one ground water sample, one surface water sample (partly fortified)
  Details: UBA and Annual Programme 2026
• Synthetic samples (IFA): Concentration comparable to ground and surface water, more details can be found here.
  
• The specified standard deviations for proficiency assessment (z-score-criteria in %) and lower limits apply to synthetic samples in the year 2026 and are calculated from interlaboratory comparisons 2015-2025.
  The standard deviations are recalculated and updated at regular intervals.



Parameter	standard deviation for proficiency assessment based on the assigned value	Lower limit
Alkalinity KS 4.3 (as H+)	1.8 %	0.2 mmol/L
Ammonium (as NH4+)	11 %	0.01 mg/L
Boron	6.8 %	0.012 mg/L
Calcium	3.1 %	9 mg/L
Chloride	2.7 %	2 mg/L
Conductivity (25°C)	1.1 %	50 µS/cm
Free Cyanide 1)	14 %	0.01 mg/L
DOC (as C)	5.3 %	1 mg/L
Fluoride 4)	7.0 %	0.2 mg/L
Hydrogen carbonate	2.3 %	20 mg/L
KMnO4-Index (as O2) 2)	8.1 %	1 mg/L
Magnesium	3.5 %	1 mg/L
Total-N 3)	-	-
Nitrate (as NO3-)	2.9 %	2 mg/L
Nitrite (as NO2-)	5.4 %	0.01 mg/L
Orthophosphate (as PO43-)	8.7 %	0.015 mg/L
pH value 3)	-	-
Potassium	3.7 %	0.5 mg/L
Silicon 4)	4.6 %	0.9 mg/L
Sodium	3.0 %	1 mg/L
Sulphate (as SO42-)	3.0 %	3 mg/L
Total hardness	2.7 %	0.1 mmol/L
Total-P (as PO43-) 5)	8.2 %	0.015 mg/L


¹⁾ Easily liberatable cyanide EN ISO 14403-2:2012; ISO 6703-2:1984 (DIN 38405-D13) in round N183
²⁾ KMnO₄-Index (EN ISO 8467-H5) in rounds N182 and N184
³⁾ Total-N and pH value in N180 (natural samples)
⁴⁾ Total-Si (as Si) and fluoride in rounds N181 and N183
⁵⁾ Total-P (as PO₄^3-) (dissolved) after digestion (EN ISO 6878:2004)




Proficiency testing round	Registration deadline	Dispatch	Organisation	Proficiency testing item	Additional	Closing date
N180	20.01.2026 *)	03.02.2026	UBA	natural	Total-N, pH value	03.03.2026
N181	02.03.2026 *)	16.03.2026	IFA	synthetic	Si, F-	17.04.2026
N182	25.05.2026 *)	08.06.2026	IFA	synthetic	KMnO4-Index	03.07.2026
N183	24.08.2026 *)	07.09.2026	IFA	synthetic	Cyanide, Si, F-	02.10.2026
N184	02.11.2026 *)	16.11.2026	IFA	synthetic	KMnO4-Index	11.12.2026


^*) Registration after the registration deadline: on request


• Contact IFA: Uta Kachelmeier, Ing.
  Phone: +43(0) 1 47654 97306
• Contact UBA: Martha Schmid, MSc.
  Phone: +43(0) 1 31304 4334