78-6 Environmental
photoelectric colorimeter. A light source is directed through a filter (making it monochromatic),
th
en
pa
ssed
th
rough
th
e
sa
mple
ce
ll
an
d
on to th
e
ph
otoelectric
de
tector
. Th
e
ob
vious
ad
vantage
ov
er
th
e
co
mparator
is th
e
el
imination
of th
e
hu
man
fa
ctor
fo
r
id
entifying
va
riations
in co
lor
.
An
other
ad
aptation
is th
e
sp
ectrophotometer,
wh
ich
em
ploys
a di
ffraction
gr
ating
to se
lect
th
e
wa
velength
fo
r
a wi
de
va
riety
of us
es
. It is a ve
ry
ve
rsatile
in
strument
si
nce
bo
th
th
e
in
coming
an
d
ou
tgoing
wa
velengths
ar
e
se
lectable
. Ne
wer
mo
dels
in
corporate
co
mputer
ch
ips
fo
r
au
tomatic
pr
o-
gramming
an
d
da
ta
st
orage
.
Colorimetric tests include single analyte meters for chlorine and DO, and direct readout multianalyte
ph
otometers
fo
r
ma
ny ...