Introduction - Determination of Anions in Natural and Treated Waters - page 31

dispersive spectrometer fitted with an Si(Li) detector and multi-channel analyser supplied
by Link Analytical. The new system, which will be described later, known as the EXTRA
II, represents the first commercially available TXRF instrument.
The attractive features of TXRF can be summarised as follows:

• An inherent universal calibration curve is obtained as a smooth function of atomic
number
• The use of internal single-element standardisation eliminates the need for matrix-
matched external standards
• Only small sample volumes are required (5-50µL).
• The technique requires only a simple sample preparation methodology.

The attractive features of the TXRF technique outlined above suggest that TXRF has the
potential to become a very powerful analytical tool for trace-elemental determinations
applicable to a wide range of matrix types and may, indeed, compete with the inductively
coupled plasma mass spectrometry.
Various suppliers of energy-dispersive and energy-refection instruments are listed in
Table 1.7.

Table 1.7 Energy dispersive and total reflection X-ray fluorescence spectrometers

Supplier Model Type Sample

types

Computer Handling of
peak
overlaps

Element
range

Detector

Link
Analytical

XR
200/300

Energy
dispersive

Solid
and
liquid

Yes Filtered least

squares
technique

Atomic
numbers
15-55
(Mo-Ba)

10mm 2
155eV
resolution Si
(Li) detector

Pye
Instruments
(Philips)

PW
1404

Energy
dispersive
sequential

Solid
and
liquid

Yes Various

techniques

B-U Argon flow

scintillation

Seifert Extra

III

Energy
dispersive
and
multiple
total
reflection

Solid
and
liquid

Yes No correction

for matrix
effects
required
except for
those in the
range sodium
to phosphorus

All
elements
beyond
sodium

80mm 2
165eV Si
(Li) detector

Source: Own files

Philips PW 1404 energy-dispersive X-ray fluorescence spectrometer
The Philips PW 1404 is a powerful versatile sequential X-ray spectrometer system
developed from the PW 1400 series and incorporating many additional hardware and