310
8 Analytical Chemistry and Quality
As
Cd
Cr
Cu
Pb
Hg
True value
1
0.05
0.05
5
5
0.5
Laboratory
1
1200
0.04
0.01 1
5.1
4.8
0.485
2
< 0.01
0.03
<0.05
4.78
< 0.05
0.05
3
0.959
0.053
0.048
4.59
4.5
0.40
4
0.861
0.052
0.062
4.85
3.9
0.05
5
0.052
0.050
0.06
4.8
3.6
0.05
6
< 0.05
0.05
0.05
5.2
5
0.05
7
0.86
0.057
0.05
5.2
3.5
0.41
8
0.87
0.05
0.057
5.0
5.2
0.5
9
0.90
0.051
0.051
4.98
4.9
1.23
10
0.86
0.067
0.067
4.9
4.6
0.49
The most significant discrepancies from the values held as true are boldfaced. The greatest
divergences correspond to the determination of arsenic, the CMPs for which were more complicated and prone to error.
As in the example of Box 8.1, a need clearly exists to institute quality systems in these
analytical laboratories.
8.2 A Generic Approach to Quality
8.2.1 Integral Definition of Quality
Most people know what quality is and use this word properly in a general context. Providing an accurate definition for quality, however, is made difficult by
the many facets it encompasses, which call for a combined approach to its
meaning.
In basic terms, quality can be defined as the body of characteristics, properties,
attributes or abilities of an entity that make it better or worse than, or equal to,