Semi-quantitative (SQX) analysis of UltraCarry method for SPEX LPC Standard 1

The UltraCarry preparation method concentrates any aqueous liquid sample on a specially designed absorbent pad that is mounted on a Mylar film, which is stretched across a rigid plastic disk. This unusual sample holder (Figure 1) allows the Rigaku ZSX Primus II WDXRF spectrometer to do a standard water type analysis in only a few minutes and attain values at the ppb level, which rival the competitive ICP analysis method for sensitivity- while offering a reduced preparation time, sample quantity, and waste.

unusual sample holder allows the Rigaku to do a standard water type analysis in only a few minutes
Figure 1

SPEX LPC Standard 1 is an aqueous liquid sample that contains 20 ppm concentrations of a full suite of elemental components, along with a few spiked addition elements at 100 ppm and 5 ppm. 500 microliters of liquid sample was deposited and then dried (60°C for 45 min.) on the UltraCarry holder. The sample was then run through the "standardless" SQX analysis software on the Rigaku ZSX Primus II Spectrometer under a vacuum atmosphere. The resulting semi-quantitative spectral scan (Figure 2) and results (Chart 1) from the sample are shown below.

resulting semi-quantitative spectral scan
Figure 2

Element
SPEX LPC1
standard value (ppm)
Rigaku SQX
analyzed value (ppm)
Calculated
LLD (ppb)
Na 20.0 18.5 76
P 100.0 90.8 56
K 100.0 116.0 12
V 100.0 18.8 34
Cr 20.0 19.1 26
Mn 20.0 20.6 16
Fe 20.0 19.3 18
Co 20.0 19.7 17
Ni 20.0 20.3 20
Cu 20.0 18.2 19
Zn 20.0 17.8 18
As 20.0 19.2 16
Se 20.0 17.8 24
Sr 20.0 19.0 25
Mo 20.0 18.4 27
Ag 5.0 3.4 152
Cd 20.0 22.3 182
Sn 20.0 22.5 40
Sb 20.0 21.5 43
Ba 20.0 17.5 105
Tl 20.0 20.1 81
Pb 20.0 17.4 76

Chart 1: SQX analysis with UltraCarry
SPEX LPC Standard 1 (100 s count time)
RoHS/WEEE hazardous element suite highlighted in blue.

The Lower Limits of Detection (LLD) for this standard are calculated, based on a 100-second count time per element and a power signature of 2.5 kW, and reported in ppb units. As the data states, the sensitivity-increasing UltraCarry method for analyzing aqueous liquids allows a standard like SPEX LPC 1 to be reported at levels that rival ICP techniques.