Wet chemical analysis and spectrometry - method catalogue


ICP-OES:

Inductively Coupled Plasma with Optical Emission Spectrometry

Principle: The analyte solution is sprayed as an aerosol into an argon plasma. At temperatures of 6500 K the elements are atomized and/or ionized. The temperature is high enough to excite atoms and ions electronically so that they emit light. The resulting spectrum consisting of many emission lines is split up by an Echelle optics. The intensity of the emission lines is proportional to the concentration of the analyte.

Application:Simultaneous determination of main, minor and trace elements

determination limit:0,01 - 1 µg/L  (depends on element)


Accuracy:0,2 - 1 % relative standard deviation

Instruments:iCAP6500 DUO (Thermo Fisher Scientific GmbH)
IRIS Intrepid II XUV (Thermo Fisher Scientific GmbH)


ICP-MS:

Inductively coupled plasma mass spectrometry

Principle:The elements are ionized in the plasma flame of an argon plasma and analyzed by a high resolution mass spectrometer. Methods of sample introduction into the flame are a nebulizer for liquid samples or laser ablation for solid samples. In laser ablation the sample is vaporized by pulsed laser shots and swept into the plasma by a gas flow. This enables a localized and spatially resolved analysis of solids.

Application:Simultaneous determination of main, minor and trace of most elements in water based liquids (except H, C, N, O, noble gases); laterally and spatially resolved analysis of solids, depth profiles of solids, investigations on layered materials, e.g. trace analysis in carbon nanotubes and fullerenes, trace element analysis in copper plated microelectronic structures

Determination limit10E-9 - 10E-7 M in liquid samples, ng - mg/g range for solids (depends on element and matric)

Accuracy:0,5 - 5 % relative standard deviation

Instruments:Element XR (Thermo Fisher Scientific GmbH)


AAS-GF

Atomic Absorption Spectrometry with graphite furnace

Principle:The analyte solution is dropped into an electrically heated graphite furnace. At temperatures between 2000 and 2800 K the sample is vaporized and atomized. Light of a certain wavelength is passed through the furnace and is adsorbed by the atomized analyte element. The required wavelength that can be adsorbed by the atomized element is emited from a hollow-cathode lamp made from the element that has to be analyzed.The AAS 6 vario (see  under devices) works with a deuterium lamp for background correction.

Application:Single element analysis of minor and trace components for most of the metals, e.g. Pd in Ag-based cover-material of superconductors, trace element analysis in thin layer materials, fullerenes and carbon nano tubes.

Determination limit:0.01 - 100 µg/L (*)
(depends on element)
(*) concentration of analyte in solution

Accuracy:about 0.5 - 5 %

Instruments:AAS 6 vario (Analytik Jena AG) graphite furnace


Titrimetry

Principle:In a titrimetry increments of a reagent solution -the titrant- are added to the analyte until their reaction is completed. From the quantity of titrant required, the quantity of analyte in the unknown sample can be calculated. The  requirements for a titrimetry reaction are to have a large constant equilibrium and to proceed rapidly. The most common titrations are based on acid-base, oxidation-reduction, complex formation or precipitation reactions. The equivalence point occurs when the quantity of added titrant comes  to the exact amount necessary for stoichiometric reaction with the analyte. Actually measured is the end point, which is marked by a sudden change of a physical property, e.g. the electrochemical potential, conductivity, pH, the color of an indicator (spectrophotometric titrimetry) etc..

Application:Precise main component analysis of metals (except alkali metals), precise determination of stoichiometries and oxidation numbers, determination of concentrations of acids and bases

Determination limit:about 0.5 mg
Accuracy:about 0.1 - 1 %

Instruments:Automatic titration system DL 77 (Mettler Toledo) with several electrodes and phototrodes


UV/VIS-Spectrophotometry

Principle:The analyte forms by a reaction with an organic agent  a colored complex. The light absorption of the colored solution is measured  at a certain wavelength in the visible or UV spectral range. The absorption is proportional to the concentration of the analyte.

Application:wide application range from main and minor component analysis and also trace analysis of numerous transition metals, e.g. Fe, Co, Ni, Ti, e.g. Determination of Fe in numerous alloys e.g. hard magnetic alloys (Fe-Nd-B based) and soft magnetic alloys (Fe-Si-B), in steel, and numerous intermetallic compounds

Determination limit:between 5 and 50 µg/g


Accuracy:about 0.5 - 2 %

Instruments:UV-VIS spectrophotometer Specord 250 (Analytik Jena AG)