2.7 Relationships among Analytical Properties
75
a highly sophisticated,expensive, operationally complex instrument such as a neutron activation detector.The techn ique of choice will be that resulting in the minimum possible cost; this
will depend strongly on the number of samples per day that the laboratory is expected to
process.
The figure above uses a log- log scale to represent costs (in an arbitrary currency) as a function of the number of analyses per day to be performed with each analytical technique.
As can be seen:
(a) The initial cost (1 sample/day) differs markedly among choices and is related to technical
com plexity.
(b) The way cost increases with increase in the number of samples per day also varies
strongly among techniques. Thus, only for distillation is the variation linear. Also, the cost
per sample remains constant over some ranges (e. g. it costs the same to analyse 10 or
100 samples by neutron activation). As a rule, the use of a sophisticated techn ique is only
justified when a large number of samples per day are to be processed.
In practice, the goal is to minimize costs in the throughput zone considered. Cost points allow one
to bound such lones. Thus, between 1 and 8 samples/day, distillation is the technique of choice
for our problem; from 8 to 200, the selective electrode is to be preferred; between 200 and 500,
the autoanalyser is the most cost-effective choice; finally, above 500 samples/day, neutron activation becomes the most inexpensive choice in the long run . The other cost points come into play
when the laboratory concerned has no access to a more affordable analytical technique.
2.6.3 Personnel-related Factors
The human factor is no doubt crucial to any activity involving personnel, as is
the case with laboratory operations. While not properties or attributes in a strict
sense, personnel-related factors are practical aspects of a high significance to the
analytical process. There are two broad types of factors, namely:
(a) Those related to the safety of the operator, laboratory staff and environment
(waste production), which have promoted major strategic changes in
modern laboratories and have a direct a impact on costs.
(b) Those related to the comfort of the laboratory staff, which should be aimed
at avoiding time-consuming tasks that might lead to stressing situations,
and at fostering creativity and competitivity via effective technical and
economically rewarding incentives.
2.7 Relationships among Analytical Properties
As noted in Sect. 2.1, it is a glaring error to deal with analytical properties in isolation. Such an approach is rather unrealistic. In fact, the properties are related
to one another in ways that can be as important as the properties themselves.
Some comment on such relationships is thus warranted at this point, where each
individual property has been described in some detail. Figure 2.14 shows a
75
a highly sophisticated,expensive, operationally complex instrument such as a neutron activation detector.The techn ique of choice will be that resulting in the minimum possible cost; this
will depend strongly on the number of samples per day that the laboratory is expected to
process.
The figure above uses a log- log scale to represent costs (in an arbitrary currency) as a function of the number of analyses per day to be performed with each analytical technique.
As can be seen:
(a) The initial cost (1 sample/day) differs markedly among choices and is related to technical
com plexity.
(b) The way cost increases with increase in the number of samples per day also varies
strongly among techniques. Thus, only for distillation is the variation linear. Also, the cost
per sample remains constant over some ranges (e. g. it costs the same to analyse 10 or
100 samples by neutron activation). As a rule, the use of a sophisticated techn ique is only
justified when a large number of samples per day are to be processed.
In practice, the goal is to minimize costs in the throughput zone considered. Cost points allow one
to bound such lones. Thus, between 1 and 8 samples/day, distillation is the technique of choice
for our problem; from 8 to 200, the selective electrode is to be preferred; between 200 and 500,
the autoanalyser is the most cost-effective choice; finally, above 500 samples/day, neutron activation becomes the most inexpensive choice in the long run . The other cost points come into play
when the laboratory concerned has no access to a more affordable analytical technique.
2.6.3 Personnel-related Factors
The human factor is no doubt crucial to any activity involving personnel, as is
the case with laboratory operations. While not properties or attributes in a strict
sense, personnel-related factors are practical aspects of a high significance to the
analytical process. There are two broad types of factors, namely:
(a) Those related to the safety of the operator, laboratory staff and environment
(waste production), which have promoted major strategic changes in
modern laboratories and have a direct a impact on costs.
(b) Those related to the comfort of the laboratory staff, which should be aimed
at avoiding time-consuming tasks that might lead to stressing situations,
and at fostering creativity and competitivity via effective technical and
economically rewarding incentives.
2.7 Relationships among Analytical Properties
As noted in Sect. 2.1, it is a glaring error to deal with analytical properties in isolation. Such an approach is rather unrealistic. In fact, the properties are related
to one another in ways that can be as important as the properties themselves.
Some comment on such relationships is thus warranted at this point, where each
individual property has been described in some detail. Figure 2.14 shows a