Environmental Engineering Reference
In-Depth Information
TABLE 7.1
Example of XRF Excitation Conditions That Optimize Detection Limits and Minimize
Spectral Interferences for Different Elements
Primary X-Ray
Tube Voltage
(kV)
Primary X-Ray
Tube Current
(mA)
X-Ray Line
Detected
Secondary
Target
Analysis
Time (s)
Elements Quantiied
Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc
Ca
400
40
15
Kα
Cs, Ba, La, Ce
Al
2
O
3
200
100
6
Kα
Ca, Sc, Ti, V, Cr
Fe
400
40
15
Kα
Mn, Fe, Co, Ni, Cu, Zn
Kα
Ge
400
75
8
Ga, As, Se, Br, Rb,
Kα
Zr
200
100
6
Hf, Ta, W, Ir, Au, Hg, Tl, Pb
Lα
Zr
200
100
6
Zr, Nb, Mo
Kα
Ag
200
100
6
Sr, Y
Kα
Mo
200
100
6
U
Lα
Mo
200
100
6
Pd, Ag, Cd, In, Sn, Sb
Kα
BaF
2
200
100
6
Sm, Eu, Tb
Kα
Al
2
O
3
200
100
6
Laser ablation ICP-MS (Chin et al., 1999; Coedo et al., 2005; Durrant, 1999; Gligorovski et al.,
2008; Owega et al., 2002; Panne et al., 2001; Tan et al., 2002; Tanaka et al., 1998) is being eval-
uated as an alternative to hard acid digestion. A high-powered pulsed laser vaporizes a portion
of the ilter deposit for direct injection into the ICP-MS. This could be applied to only a portion
of the Telon-membrane ilter, leaving the remainder for additional characterization. The method
requires calibration standards, equivalence testing, and optimization with respect to reproducibility,
standardization, and detection limits.
7.4.5 i
on
c
HroMatograPHy
a
nalysis
For
a
nions
and
c
ations
Water-soluble inorganic ions are directly emitted by sources and form from directly emitted gases—
with nitrate (NO
3
−
), sulfate (SO
4
=
), and ammonium (NH
4
+
) contributing large quantities to PM
2.5
and PM
10
concentrations (Malm et al., 2002; Sisler and Malm, 1994). Ion chromatography (IC)
(e.g., Dionex ICS-3000, Sunnyvale, CA) sends a water-extracted sample through an ion exchange
column to separate the ions retention time for individual quantiication in a conductivity detector.
Prior to detection, the column efluent enters a suppressor column where chemical composition of
the component is altered, resulting in a matrix of low conductivity (Chow and Watson, 1999; Mulik
and Sawicki, 1978, 1979). The ions are identiied by their elution/retention times and quantiied by
the conductivity peak area. Peak areas are related to concentrations from standard solutions (e.g.,
ERA, Arvada, CO) for quantiication.
Chloride (Cl
−
), nitrate (NO
2
−
), NO
3
−
, phosphate (PO
4
≡
), and SO
4
=
are the commonly measured
anions using a guard column (AG14 column, Cat. No. 046134) plus an anion separator column
(AS14 column, 250 × 4 mm ID, Cat. No. 046129) with a strong basic anion exchange resin, and
an anion micro-membrane suppressor. The anion eluent consists of 0.0035 M sodium carbonate
(Na
2
CO
3
) and 0.001 M sodium bicarbonate (NaHCO
3
) prepared in DDW. Lithium (Li
+
), sodium
(Na
+
), ammonium (NH
4
+
), potassium (K
+
), magnesium (Mg
++
), and calcium (Ca
++
) are commonly
measured cations using a guard column (CG16 column, 5 × 50 mm, Cat. No. 057574) and a separator
column (CS16, 5 × 250 mm, Cat. No. 057573). The cation columns use a hydrophilic, high-capacity,
and carboxylate functionalized cation exchange resin. For cations, a micro-membrane suppressor, is
used to reduce background conductivity. The eluent is 30 Nm methanesulfonic acid (MSA).
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