EPA-NERL: 200.8:  Metals in Waters by ICP/MS

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
Determination of Trace Elements in Waters by Inductively Coupled Plasma - Mass Spectrometry
Current Revision
Revision 5.4, 1994
Inductively Coupled Plasma - Mass Spectrometry
Method Subcategory
Method Source
  Methods for the Determination of Metals in Environmental Samples, Supplement 1 (EPA/600/R-94/111)
Brief Method Summary
Except for the determination of dissolved analytes aqueous samples are acid preserved prior to sample processing. For the analysis of dissolved analytes, an acidified portion the filtrate is analyzed directly. For the determination of total-recoverable analytes in aqueous samples containing particulate material as well as solid type samples, samples are subjected to acid pretreatment with nitric and hydrochloric acids and gentle refluxing prior to analysis. The method involves multi-element determination by inductively coupled plasma-mass spectrometry. Sample solutions are pneumatically nebulized into a radio-frequency plasma where ionization occurs. The ions are extracted from the plasma through a differentially pumped vacuum interface and separated on the basis of their mass-to-charge ratio by a quadruple mass spectrometer. Separated ions are detected by an electron multiplier or Faraday detector and the ion information processed by a data handling system. Isobaric and polyatomic interferences relating to the technique must be recognized and corrected. Instrument drift and matrix effects must be corrected with the use of internal standards.
Scope and Application
This method determines 21 elements as dissolved elements in ground waters, surface waters, and drinking water, and total recoverable elements in these waters as well as wastewaters, sludges, and soils samples. Total-recoverable determination data should be reported as "total" (dissolved + suspended fractions) metal data. Organometalic compounds (such as arsenic compounds) are only determined as "total metals" and not as the individual organometalic compounds.
Applicable Concentration Range
The analytical range depends on the type of detector utilized (electron multiplier or Faraday cup) and extends from the laboratory determined MDL to the upper limit of the linear dynamic range.
(1) Isobaric elemental interferences caused by isotopes of different elements which form singly or doubly charged ions of the same nominal mass-to-charge ratio and cannot be resolved by the mass spectrometer in use.
(2) Signals from relatively abundant isotopes can coalesce at the wings of relatively less abundant isotopes leading to loss of resolution and poorer quantitation.
(3) Isobaric polyatomic ion interferences are caused by ions consisting of more than one atom with the same nominal charge-to-mass ratio of the isotope of interest.
(4) Physical interferences that hinder transport of the sample into the plasma (e.g., viscosity effects, high levels of solids).
(5) Memory interferences (carry-over) of isotopes from previous sample runs.
Quality Control Requirements
Calibration Blanks (CBs), Laboratory Reagent Blanks (LRBs), Laboratory Duplicates (LDs), Laboratory Fortified Sample Matrix (LFM), Quality Control Samples (QCSs)
Sample Handling
For dissolved elements, filter aqueous sample through a 0.45-um pore membrane filter. Adjust the pH of the filtrate to < 2 with HNO3. For total recoverable elements, adjust the pH of the aqueous sample to < 2 with HNO3.
Maximum Holding Time
6 months (All metals except Hg - 28 days)
Relative Cost
$201 to $400
Sample Preparation Methods