152
4 The Measurement Process in Chemistry
Box 4.4
Selected examples illustrating variety in preliminary operations
Sample
Analytes
Combination
Usual sample
type
treatment
State of Nature
aggregation of Of
Of
sample matrix analyte
Soil
Metals
S
I
I
• Leach ing
• Disaggregation
Pesticides
S
I
0
• Solvent extraction
Serum
Urea
L
B
0
• Dialysis
Enzymes
L
B
B
• Dilution
Lead
L
B
I
• Destruction of
organic matter
Drugs
L
B
0
• L-L andSP
extraction
Air
Metal traces
G(S)
I
I
• Ion exchange
(particulates)
• S- L extraction
Organic
G(S)
I
0
• L - L extraction
pollutants
PharmaVitamins
S(l)
OIl
B
• l eachi ng: H2O
ceutical
(water-solubles),
(vitamin
o. s. (fat-solubles)
complex)
Salts
S(l)
OIl
I
• Destruction of
organic matter
Excipients
S(l)
OIl
0
• L - L extraction
Animal
Metals
S
B
I
• Freeze-drying
tissue
Additives (human S
B
0
• leaching
consumption)
Proteins
S
B
B
• Leaching
Fresh
Ascorbic acid
l
B
B/O • None needed
orange
juice
Artificial
l
B
0
• l - L extraction
sweeteners
Metal traces
L
B
I
• Ion exchangel
elution
S solid, L liquid, G gas, SP solid-phase, I inorganic, 0 organic, B biological, o. s. organic solvent.