Simultaneous determination of lanthanum and europium by higher order derivative molecular absorption spectrophotometry

The identical properties of rare earth elements towards reaction with various chromogenic reagents in molecular absorption spectrophotometry (MAS) leads to a requirement for the development of procedures with greater selectivity. One way of solving this problem is by utilizing derivative spectroscopy, where the composite spectrum is transformed to the second or higher order derivative in wavelength domain. This paper reports the utilization of higher order derivative spectrophotometry for the simultaneous determination of lanthanum and europium. The developed procedure is simple, reliable and allows the determination of as low as 100 and 10 ppb of lanthanum and europium, respectively. Similar methodology can be adopted for the simultaneous determination of two or more of any closely related analytes by proper choice of derivative order in addition to selecting a suitable chromogenic reagent, pH and masking agents