Lanthanides are of increasing technological importance, but the techniques commonly used to determine them require equipment well beyond the means of small budgets, according to Metrohm UK.
However, ion chromatography applying non-suppressed conductivity or UV/VIS detection is a straightforward and less expensive alternative.
Lanthanides are commonly determined by atomic absorption spectroscopy, X-ray fluorescence, inductively coupled plasma-mass spectrometry (ICP-MS) or inductively coupled plasma-atomic emission spectroscopy (ICP-AES).
Sophisticated as they are, these techniques go along with high costs of instrumentation and require highly skilled operators.
The determination of trace levels of lanthanides by ion chromatography is achieved by using either direct non-suppressed conductivity detection or UV/VIS detection at 655nm after post-column reaction (PCR) with arsenazo III.
Conductivity detection under isocratic conditions results in overall analysis times of approximately 70 minutes.
A much faster way is the determination of lanthanides via gradient elution and subsequent spectrophotometric detection of the arsenazo III-lanthanide(III) complexes, which can be performed within just 22 minutes.
Other than the short analysis time, UV/VIS detection excels by its selectivity and sensitivity and does not suffer from interferences by ever-present impurities such as iron(III) or other transition metals.