Determining Element Contents in Seawater

This analytical procedure is designed to measure the concentration of various metals in seawater samples; including arsenic, barium, cadmium, cobalt, manganese, copper, iron, nickel, lead, strontium and zinc.

The MGA-1000 Graphite Furnace AA Spectrometer is used to determine the dissolved forms of the elements in samples with as much as 50% salinity (including water from estuaries and oceans).

The measurement ranges of the procedure cover all of the specified maximum allowable concentration levels and enable accurate determination of the elements within the naturally occurring range of concentrations.

As a result of the advanced Zeeman background correction system of the MGA-1000, the procedure does not require extensive sample preparation, and the calibration procedure is simplified.

Measurement Method

This technique works by measuring the absorption of light at the resonant wavelength when radiation from a spectral lamp traverses atomic vapor, which is formed in the electrically heated graphite furnace of the spectrometer during the thermal decomposition of the injected sample.

The integrated absorption signal indicates the elements’ concentrations, which are calculated with the use of a preset calibration graph.

Measurement Range

The table below lists the measurement ranges (with dilution).

Element Measurement range,
μg/L
As 2.5 – 2000
Ba 20 – 20000
Cd 0.2 – 200
Co 2 – 2000
Cu 2 – 2000
Fe 5 – 2000
Mn 5 – 2000
Ni 2 – 2000
Pb 2 – 2000
Sr 50 – 20000
Zn 5 – 2000

 

Equipment and Reagents

When carrying out measurements, the below reagents and equipment are used:

  • MGA-1000 graphite furnace atomic absorption spectrometer
  • Calibration standard solution of analyzed elements
  • Deionized or bidistilled water
  • A high purity grade of concentrated nitric acid
  • Lanthanum nitrate, puriss. p.a.
  • Magnesium matrix modifier for GFAAS
  • Palladium matrix modifier for GFAAS
  • Ammonium nitrate, 99.999% trace metals basis

Measurement Procedures

Prior to analysis, the sample needs to be filtered and acidified. An aliquot of the prepared sample must be injected into the graphite furnace of the spectrometer. Measurements are undertaken in line with the pre-determined analytical procedure for each specific element.

The majority of the elements require the use of an appropriate matrix modifier in order for analysis to be carried out. Included within the delivery set, the dedicated software collects and processes measurement data.

This information has been sourced, reviewed and adapted from materials provided by Lumex Instruments.

For more information on this source, please visit Lumex Instruments.

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