Documents\Palladium-contents. Pdf

Table 4. Physical and chemical properties of selected palladium compounds
Chemical name
Appearance 
Molecular
mass (g)
% Pd
Melting
point
(°C)
a
Solubility
in water
Solubility in 
other solvents
Relative
density
(g/cm
3
)
Reference
Bis(acetylacetonato)
palladium(II)
yellow
crystals
304.64
34.9
NAS (1977)
Bis(dibenzylidene-
acetone) palladium(0)
purple
powder
575.02
18.5
NAS (1977)
Diamminedinitro-
palladium(II)
yellow
232.5
45.8
slightly
soluble
soluble in ammonium
hydroxide
Degussa (1995)
Dichloro(1,5-cyclo-
octadiene) palladium(II)
yellow
crystals
285.51
37.3
NAS (1977)
Palladium(II) chloride
rust colour
powder
177.33
60
675 or
501
b
(dec.)
soluble
soluble in hydrochloric
acid, alcohol, acetone
4
Sax & Lewis (1987);
Budavari et al.
(1996)
Palladium(II) acetate
reddish-
brown
crystals
224.51
47.4 
200 
(dec.)
insoluble
soluble in hydrochloric
acid or potassium iodide
solution
Sax & Lewis (1987);
Budavari et al.
(1996)
Palladium(II) iodide
black powder
360.21
29.5
350 
(dec.)
insoluble
soluble in potassium
iodide solution
6 
Sax (1979); Sax &
Lewis (1987)
Palladium(II) oxide
black-green
or amber
solid
122.4
87
750
(dec.)
insoluble
soluble in dilute aqua
regia, 48% hydrobromic
acid
8.3
Sax (1979); Sax &
Lewis (1987)

---

Table 4 (contd).
Chemical name
Appearance 
Molecular
mass (g)
% Pd
Melting
point
(°C)
a
Solubility
in water
Solubility in 
other solvents
Relative
density
(g/cm
3
)
Reference
Palladium(II) acetate
trimer
gold brown
crystals
673.53
47.4
insoluble
soluble in acetic acid
NAS (1977)
Palladium(II) nitrate
brown salt
229.94
(anhydrous)
~46.2
dec.
soluble
soluble in dilute nitric
acid
Sax & Lewis (1987);
Budavari et al.
(1996)
Potassium
chloropalladate
cubic red
crystals
397.3
53.6
(dec.)
2.7
Sax (1979)
Potassium
tetrachloropalladate(II)
reddish-
brown
crystals
326.4
32.6
524
soluble
slightly soluble in hot
alcohol
2.7
Sax & Lewis (1987)
Sodium
tetrachloropalladate(II)
red brown
powder
294.21
37
NAS (1977)
Tetraammine-
palladium(II) chloride
yellow
245.4
43.4
soluble
Degussa (1995)
Tetraammine palladium
hydrogen carbonate
219.4
48.5
181 
(dec.)
soluble
(56.2
g/litre at
20 °C)
Johnson Matthey
(2000)
Tetrachloropalladic(II)
acid
dark brown
250.2
42.5
only stable in solution of
hydrochloric acid

---

Table 4 (contd).
Chemical name
Appearance 
Molecular
mass (g)
% Pd
Melting
point
(°C)
a
Solubility
in water
Solubility in 
other solvents
Relative
density
(g/cm
3
)
Reference
Tetrakis(triphenyl-
phosphine) palladium(0)
yellow
crystals
1155.58
9.2
insoluble
soluble in acetone,
chlorinated
hydrocarbons, benzene
NAS (1977)
trans-Diamminedichloro-
palladium(II)
orange
crystals
211.39
50.3
soluble 
(2.7
g/litre)
soluble in ammonium
hydroxide
NAS (1977)
trans-Dichlorobis-
(triphenylphosphine)
palladium(II)
yellow
crystals
701.91
15.2
NAS (1977)
a
dec. = decomposes.
b
From Sax (1979).

---

EHC 226: Palladium
22
Cellulose ion exchangers  (Kenawy  et al., 1987), 2,2
N
-dipyridyl-3-(4-
amino-5-mercapto)-1,2,4-triazolylhydrazone supported on silica gel
(Samara  & Kouimtzis, 1987) or automated on-line column  separation
systems  (Schuster & Schwarzer, 1996), were  used to preconcentrate
traces of palladium(II) from water samples.
For laboratories  engaged in analyses  of geological samples, the
fire assay fusion seems  to be the preferred method of dissolving and
concentrating palladium. Palladium metal can be preconcentrated using
either a  lead collection or a nickel sulfide collection. The sensitivity of
the nickel sulfide fire assay is limited by background palladium
introduced by the high amounts  of chemicals (e.g., nickel) employed
(McDonald et al., 1994).
With biological materials, homogeneous sampling is  difficult  and
often requires destructive methods, resulting in the loss of all informa-
tion about the palladium species. In many of the analytical procedures,
samples  have been ashed to destroy organic  materials  and then treated
with strong acids to yield solutions for palladium determination. Only
the total content of palladium and its isotopes can then be determined.
For the analysis  of palladium in urine, the untreated original sample is
usually   unsuitable.  Freeze-drying  or  a  wet ashing procedure with
subsequent  reduction  of  volume   is   necessary   for  most  analytical
methods. For complex matrices such as blood, removal of the organic
sample  matrix combined with dilution to reduce the content of total
dissolved solids is  recommended to avoid blockages of the sampling
cone and signal instabilities  when using inductively  coupled plasma
mass spectrometry (ICP-MS). Strong mineral acids are  most frequently
applied for matrix decomposition. For blood, serum and urine digestion,
ultraviolet (UV) photolysis has also been found to be useful.
2.3.2
Reference materials
The availability of certified reference materials  is  of great value for
laboratories  engaged in analytical chemistry. For palladium analysis,
there  are  only  few international standard  reference materials, which are
directly  traceable  to the Standard Reference Material (SRM) of the US
National Bureau of Standards (NBS). Single-element A A S standards
are offered at 1 mg/ml — for example, by Aldrich (1996) — or can be
prepared according to APHA et al. (1989). To our knowledge, 

---