analysis of food contaminants i. definition and
TRANSCRIPT
AN
ALY
SIS
OF
FOO
D C
ON
TAM
INA
NTS
I. D
efin
itio
nan
dCl
assi
fica
tion
of F
ood
Cont
amin
ants
II. C
hrom
atog
raph
ic T
echn
ique
s
III.
Ana
lysi
s of
Spe
cifi
c Co
ntam
inan
ts
-Pes
tici
de A
naly
sis
-M
ycot
oxin
s-A
flat
oxin
s
-Im
mun
oass
ays
-Foo
d A
ddit
ives
I. D
efin
itio
nan
dCl
assi
fica
tion
Cont
amin
ants
are
unde
sire
dno
nnut
rien
tsu
bsta
nces
that
find
thei
rwa
yin
tofo
ods
and
food
raw
mat
eria
ls.
They
all
have
in c
omm
onth
epo
tent
ial
for
hum
anto
xici
ty,r
angi
ngfr
omac
ute
pois
onin
gto
accu
mul
atio
ndi
seas
esdu
eto
prol
onge
dex
posu
res.
The
irpr
esen
ce
in t
hefo
odch
ain
is s
urel
ya
risk
fac
tor
for
hum
anhe
alth
. Fo
odco
ntam
inan
tsar
eof
ve
rydi
vers
ech
arac
ter
in t
heir
com
posi
tion
s, a
ndm
aybe
cla
ssif
ied
as f
ollo
ws: A
. Phy
sica
lcon
tam
inan
tsB.
Bio
logi
calc
onta
min
ants
c. C
hem
ical
Cont
amin
ants
A. P
hysi
calc
onta
min
ants
■Ex
trane
ous
mat
eria
ls:A
nyfo
reig
nm
atte
r(s
and
, soi
l, gl
ass,
rust
etc.
)ass
ocia
ted
with
obje
ctio
nabl
eco
nditi
ons
of
proc
essi
ng, s
tora
geor
dist
ribut
ion
■Fi
lth: A
nym
atte
rcon
tribu
ted
byan
imal
ssu
chas
rode
nts,
inse
cts,
bird
set
c.•
1. L
ight
filth
: ole
ophi
lican
d“fl
oats
”•
2. H
eavy
filth
:sep
arat
edby
sedi
men
tatio
n
ME
TH
OD
S fo
rQ
uant
ifyin
gPh
ysic
alC
onta
min
ants
:
1.M
icro
scop
y2.
Phy
sica
lSep
arat
ions
: on
basi
sof d
iffer
ence
sin
parti
cle
size
(sie
ving
), in
den
sity
(flo
tatio
nof
inse
ctsa
ndin
sect
frag
men
ts)
3. C
hem
ical
Ana
lyse
sof “
indi
cato
rs”:
i.e. u
ricac
idco
nten
tm
easu
resi
nsec
torb
irdex
crem
ent.
4.A
utom
ated
met
hods
:ELI
SA b
ased
on d
etec
ting
inse
ctpr
otei
n “m
yosi
n” in
pla
ntfo
odsa
mpl
es.
DA
L:D
efec
tact
ion
leve
ls: C
urre
ntm
axim
umle
vels
of
unav
oida
ble
defe
ctst
hatp
rese
ntno
hea
lthha
zard
B. B
iolo
gica
lC
onta
min
ants
:M
icro
orga
nsim
stha
tinv
ade
food
com
mod
ities
can
be
iden
tifie
dan
dqu
antif
ied
bym
akin
gus
eof
con
vent
iona
lmic
robi
olog
ical
anal
yses
C. C
hem
ical
Con
tam
inan
ts:
1. H
eavy
met
als
and
radi
oact
ive
met
al
cont
amin
ants
(Env
ironm
enta
lpo
lluta
nts
tobe
det
erm
ined
by e
ither
atom
ic a
bsor
ptio
nsp
ectro
scop
y an
d/or
mea
sure
men
t of
ra
dioa
ctiv
ity)
2.To
xins
pro
duce
d by
mic
roor
gani
sms:
a-Ba
cter
ial
toxi
ns:
Myc
olog
ical
de
tect
ions
fo
llowe
d by
bio
logi
cal
test
s
(bri
ne s
hrim
p la
rvae
) or
sp
ecif
ic r
apid
tox
in
test
s ba
sed
on i
mm
unoc
hem
ical
m
etho
ds.
b-M
ycot
oxin
s(to
xic
met
abol
ites
of
mou
lds)
:M
ycot
oxin
cont
amin
atio
n is
at
pp
mle
vels
.~m
g/kg
; m
g/to
n an
d is
not
hom
ogen
ous
thro
ugho
ut t
he f
ood,
wh
ich
is a
n im
port
ant
pro
blem
for
che
mic
al a
naly
ses.
3. C
hem
ical
s us
ed in
agr
icul
tura
l pr
acti
ces
a.Pe
stic
ides
:Cu
rren
tly
ther
ear
em
ore
than
300
Chem
ical
sus
edto
ki
ll pe
sts(
inse
ctic
ides
-he
rbic
ides
-fun
gici
des)
b.
Ani
mal
dru
gs(h
orm
ones
and
ant
ibio
tics
) fo
r ra
isin
g th
e pr
oduc
tivi
ty a
nim
als,
inc
reas
ing
the
ra
tio
of l
ean
mea
t to
fat
ty m
eat,
thu
s bo
th t
he
quan
tity
an
d th
e qu
alit
y of
th
e m
eat
bein
g im
prov
ed.
The
se s
houl
d be
giv
en m
uch
prio
r to
sl
augh
ter,
th
is
peri
od
bein
g ca
lled
the
"w
ithd
rawa
l tim
e", w
hich
sho
uld
cove
r s
uffi
cien
tti
me
for
all t
ypes
of
exc
reti
ons
of t
he c
hem
ical
fr
om t
he a
nim
al b
ody.
4. M
igra
tion
fro
m p
acka
ging
mat
eria
ls:
mon
omer
s of
the
pol
ymer
s us
ed f
or f
ood
pack
agin
g (li
ke v
inyl
m
onom
er o
f PV
C).
In g
ener
al,
the
poly
mer
s ar
e in
ert
and
do n
ot m
igra
te,
wher
eas
mon
omer
s do
. Th
e vi
nyl
mon
omer
can
be
anal
yzed
by
GC u
sing
he
adsp
ace
tech
niqu
e af
ter
susp
ensi
on
in
dim
ethy
lace
tam
ide.
5.
Food
A
ddit
ives
: Th
ese
chem
ical
swh
ich
are
inte
ntio
nally
add
ed t
o fo
ods
duri
ng p
roce
ssin
gar
em
ade
upof
ve
rydi
vers
egr
oups
of
chem
ical
com
poun
ds,
each
requ
irin
gsp
ecif
icty
pes
of
anal
ysis
.
II. C
hrom
atog
raph
ic T
echn
ique
s
Ana
lysi
s of
al
mos
t al
l co
ntam
inan
ts
invo
lve
met
hods
tha
t m
ake
use
of
chro
mat
ogra
phic
se
para
tion
s.Th
e fi
rst
deve
lope
r of
thi
s ty
pe o
f m
etho
ds
was
Russ
ian
scie
ntis
t,
Tswe
lt,
who
part
itio
ned
plan
t pi
gmen
ts i
n 19
03.
All
type
s of
chr
omat
ogra
phy
invo
lve
two
phas
es,
one
stat
iona
ry a
nd t
he o
ther
mob
ile, s
epar
atio
ns
bein
g ba
sed
on t
he d
iffe
renc
es in
the
vol
atili
ty,
pola
rity
, m
olec
ular
si
ze,
elec
tric
al
char
ge,
solu
bilit
ies
and/
or
affi
niti
es o
f co
nsti
tuen
ts i
n th
e re
spec
tive
tw
o ph
ases
. Th
ere
are
five
di
ffer
ent
te
chni
ques
in
volv
ed
for
thes
e se
para
tion
s, t
he m
ain
two
bein
g th
e fo
llowi
ng:
1. A
dsor
btio
nor
dis
plac
emen
t ch
rom
atog
raph
y:
Her
e, t
he c
olum
n is
pac
ked
with
an
iner
t fi
lling
. Fi
rst
the
sam
ple
solu
tion
(i.e.
with
sol
utes
A+B
in s
elec
ted
solv
ent)
is
give
n to
the
col
umn,
whe
re c
ompo
nent
s ar
e ad
sorb
ed b
y no
ncov
alen
tbo
nds-
nonp
olar
in
acti
on.T
hen
the
fres
h
solv
ent
(mob
ile p
hase
) is
giv
en o
nto
the
colu
mn,
whi
ch
disp
lace
s so
me
of t
he s
olut
es o
f sa
mpl
e so
luti
on (
A+B
), le
avin
g th
em f
ree
to m
igra
te d
own
the
colu
mn.
Sepa
rati
on
of
solu
te
mol
ecul
es
occu
r by
eq
uilib
rati
on
betw
een
adso
rbed
sta
te a
nd s
olut
ion.
Thi
ste
chni
que
is e
ffec
tive
prim
arily
for
sep
arat
ion
of n
onpo
lar
com
poun
ds a
ccor
ding
to
the
ir f
unct
iona
l gro
ups
and
MW
.
2. P
arti
tion
chr
omat
ogra
phy:
Effe
ctiv
e fo
r fr
acti
onat
ing
mai
nly
hydr
ophi
lic
com
pone
nts
of d
iffe
ring
pol
arit
ies.
Her
e, t
he i
nert
pa
ckin
g is
coa
ted
with
a f
ilm o
f hi
gh-b
oilin
g liq
uid
that
is
stro
ngly
ads
orbe
d by
the
par
ticl
e su
rfac
e,
the
adso
rben
t co
nsti
tuti
ng t
he s
tati
onar
y ph
ase.
A
fter
giv
ing
firs
t th
e fr
esh
solv
ent
as t
he m
obile
ph
ase,
and
the
sam
ple
solu
tion
, so
me
mor
e m
obile
ph
ase
(sol
vent
) is
pa
ssed
th
roug
h th
e co
lum
n,
redi
stri
buti
ng t
he c
ompo
nent
s of
sam
ple
in t
he t
wo
phas
es,
the
mob
ile
elut
ing
solv
ent
and
the
stat
iona
ry a
dsob
ent
on t
he p
acki
ng m
ater
ial.H
ighe
r ho
mol
ogue
s m
igra
te b
efor
e sh
orte
r m
olec
ules
.
The
othe
r th
ree
chro
mat
ogra
phic
tech
niqu
es a
re
“siz
e-ex
clus
ion”
,“af
fini
ty”a
nd “i
on-e
xcha
nge”
ch
rom
atog
raph
y.
Rfva
lue:
A p
aram
eter
tha
t m
easu
res
how
far
a su
bsta
nce
mov
es w
ith
resp
ect
to h
ow f
ar t
he
solv
ent
mov
es a
t th
e sa
me
tim
e.
Rete
ntio
n ti
me,
RT,
is a
sim
ilar
conc
ept
in G
C an
d H
PLC.
Typ
es o
f Chr
omat
ogra
phy
Sta
tion
ary
phas
eM
obile
pha
seN
AM
EP
hysi
cal p
rinc
iple
Solid
Gas
Gas
-sol
idAd
sorb
tion
Solid
Liqu
idTh
in la
yer
colu
mn
pape
r
Adso
rbtio
n+p
artit
ion
Liqu
idLi
quid
HPL
Cpa
rtiti
on
Liqu
idG
asG
as-li
quid
part
ition
Para
met
ers
for
sele
ctio
n of
the
sta
tion
ary
and
mob
ile
phas
es:
For
Stat
iona
ryPh
ase:
Ads
orbt
ivity
(↓)
For
Mob
ile P
hase
:Polar
ity↑
(Al s
ilica
te (F
ulle
r's
eart
h)Pe
trol
eum
eth
er (3
0-50
°C)
Mg
silic
ate
(Flo
risi
l)CC
l4A
l oxi
des
Chlo
rina
ted
Hyd
roca
rbon
sSi
lica
gel
Ethe
r M
gOA
ceto
neN
a 2CO
3Be
nzen
e A
lcoh
ols
Wat
erA
cids
(org
anic
-inor
gani
c)[B
ase+
acid
+wat
er] m
ixtu
res
You
can
mix
any
of
the
solv
ents
giv
en u
nder
the
el
uotr
opic
seri
es
ti
ll yo
u re
ach
the
desi
red
po
lari
ty in
ord
er t
o in
crea
se o
r de
crea
se t
he R
for
RT
(ret
enti
on
tim
e)
for
the
anal
yzed
so
lute
co
mpo
nent
.
Hin
ts
for
Sele
ctio
n of
St
atio
nary
an
d M
obile
ph
ases
:
1. If
you
hav
e a
very
pol
ar s
olut
e m
olec
ule,
it w
ill
be h
eld
mor
e st
rong
ly o
n a
hydr
ophi
lic a
dsor
bent
.
Ther
efor
e, u
se a
wea
k ad
sorb
ent,
but
st
rong
er e
luti
on s
olve
nt (m
obile
).If
the
sol
ute
has
weak
aff
init
y f
or a
dsor
bent
, us
e st
rong
ads
orbe
nt(o
f hi
gh a
ctiv
ity
leve
l*)
and
weak
elu
ent
.
*Act
ivit
y Le
vel o
f St
atio
nary
pha
se is
als
o im
port
ant.
A
lum
ina(
Al 2O
3) h
as 5
act
ivit
y gr
ades
:Gr
ade
I: 0
% H
2O;
Grad
e II
: 3%
H2O
; Gr
ade
III:
6%
H
2O;
Gra
de I
V: 1
0% H
2O;
Grad
e V:
12%
H2O
-mos
t ac
tive
.
Sum
mar
y:N
orm
al P
hase
•Sta
tion
ary
phas
e→Po
lar
•Mob
ile p
hase
→N
on-p
olar
•Fir
st t
o el
ute→
leas
t po
lar
com
pone
nts
•Las
tto
elut
e: m
ost
pola
rsRe
vers
ed P
hase
•Sta
tion
ary
phas
e→N
on-p
olar
•M
obile
pha
se→
Pola
r•F
irst
to
elut
e→m
ost-
non
pola
rs•L
ast
to e
lute
→le
ast
pola
rs(n
on p
olar
)
III.
Ana
lysi
s of
Spe
cifi
c Co
ntam
inan
ts:
EXA
MPL
E 1:
Pes
tici
de A
naly
sis
Firs
t of
all,
che
ck w
hat
type
s of
pes
tici
des
are
allo
wed
and
are
used
for
you
r sa
mpl
efo
odco
mm
odit
yin
res
pect
ive
food
legi
slat
ion.
Then
sta
rt w
ith
a m
ulti
resi
due
scre
enin
g te
st
type
of
anal
ysis
(i.e
. En
zym
atic
acet
ylch
olin
este
rase
test
fo
ral
lor
gano
phos
phou
spe
stic
ides
) an
d fo
rpo
siti
vesa
mpl
es,
conc
lude
wit
h of
fici
alan
alyt
ical
met
hod(
eit
her
one
of
the
mul
tire
sidu
e(M
RM)
orsi
ngle
resi
due(
SRM
) m
etho
d)fo
r th
e sp
ecif
ic p
esti
cide
ide
ntif
ied.
St
eps
in
anal
yses
:1.
Sam
ple
prep
arat
ion:
D
isca
rdin
g in
edib
les
and
hom
ogen
izat
ion
2. E
xtra
ctio
n fr
om s
ampl
e m
atri
x: O
rgan
och
loro
pest
icid
es
are
non
pola
r,
thus
re
quir
e
fat
solu
ble
solv
ents
, bu
t O
rgan
opho
spha
tes
requ
ire
mor
e po
lar
wate
r so
lubl
e-so
lven
ts.
For
gen
eral
scr
eeni
ng p
urpo
ses,
yo
u ca
n us
e ac
eton
itri
le,
whic
h ex
trac
ts b
oth.
3. I
sola
tion
and
cle
an-u
p:Re
mov
al o
f in
terf
erin
g c
o-ex
trac
tive
s,
pref
erab
ly
by
co
lum
n ch
rom
atog
raph
y (p
arti
tion
ing)
or
liqui
d-liq
uid
extr
acti
on i
n se
para
tory
funn
el.
This
can
be
done
by
tran
sfer
ring
pest
icid
esto
petr
oleu
met
her
and
then
puri
fyin
gth
epe
t-et
her
extr
act
on
a Fl
uori
sil
colu
mn,
to
be
follo
wed
byst
epwi
seel
utio
nof
chlo
rous
and
phos
phor
ous
pest
icid
eswi
thdi
ffer
ent
solv
ent
syst
ems.
4.
Sepa
rati
on:C
ompo
nent
sof
pu
rifi
edex
trac
rtar
ese
para
ted
bydi
ffer
enti
alpa
rtit
ioni
ngbe
twee
na
mob
ile a
nda
stat
iona
ryph
ase(
Chro
mot
ogra
phy)
5.D
etec
tion
and
Qua
ntif
icat
ion
: A
phy
sica
lpa
ram
eter
of s
epar
ated
com
pone
nts
in m
obile
pha
seis
mea
sure
das
it
pass
esth
roug
ha
dete
ctor
, th
em
easu
red
sign
albe
ing
rela
ted
toco
ncen
trat
ion
For
TLC,
Al
oxid
e pl
ates
ar
e us
ed
whic
h ar
e sp
otte
d wi
th s
ampl
e fr
om m
icro
syri
nge
or c
apill
ary
tube
s.
The
deve
lopm
ent
tank
sh
ould
be
pr
e-sa
tura
ted
with
the
dev
elop
ing
solv
ent,
(i.e
.ace
tone
: he
ptan
e)
Aft
er
deve
lopm
ent
of
the
spot
ted
plat
e,
for
visu
alis
atio
nof
ch
lori
nate
d pe
stic
ides
,sp
ray
with
A
gNO
3so
luti
on,
then
dry
and
obs
erve
und
er U
V lig
ht.
For
visu
aliz
atio
n of
org
anop
hosp
hate
s, s
pray
wi
th a
dye
sol
utio
n (T
BPP
in a
ceto
ne).
Pest
icid
es
occu
r as
bl
uish
-pur
ple
spot
s ag
ains
t ye
llow
back
grou
nd. I
dent
ific
atio
n is
don
e ac
cord
ing
to
R fva
lues
and
qua
ntif
icat
ion
is b
y GC
(Ele
ctro
n ca
ptur
e de
tect
or
for
chlo
rim
ated
pest
icid
es;
AFD
io
niza
tion
for
org
anop
hosp
hate
s). F
or %
Rec
over
y,
inte
rnal
st
anda
rd
is
adde
d to
sa
mpl
e pr
ior
to
extr
acti
on s
tep.
EXA
MPL
E 2:
Myc
otox
ins-
Afl
atox
ins
Diffe
rent
ana
lytica
l met
hods
hav
e be
en d
evelop
ed f
or
diff
eren
t myc
otox
ins
and
even
for
the
sam
e myc
otox
inin diff
eren
t fo
od ty
pes
(mat
rix
diff
eren
tiat
ion)
. A
gene
ral pr
oced
ure
for
aflato
xins
is a
s fo
llows
:
•Folllo
wing
aque
ous
met
hano
l ex
trac
tion
of
aflato
xins
from
sa
mple
mat
rix,
af
lato
xins
are
part
itione
d to
met
hylene
chloride
in
a se
para
tory
funn
el(li
quid-l
iquid
extr
action
) us
ing
thes
e tw
o im
miscible
solven
t sy
stem
s.
•Lat
er,
clea
n-up
from
inte
rfer
ing
subs
tanc
es
like
pigm
ents
is
realized
wi
th
silic
a ge
l co
lumn
chro
mat
ogra
phy.
•T
hen
TLC
silic
agel
plat
es a
re u
sed
for
iden
tifica
tion
s of
iso
late
d to
xins
. M
obile
pha
se is
[CHCl
3 :
met
hano
l:
acet
one]
.
Visu
alizat
ion
is
done
un
der
UV
light
be
caus
e af
lato
xins
B1 a
ndB2
give
blue
fluo
resc
ense
, wh
erea
sG1
and
G2 g
ive
gree
nfluo
resc
eenc
e.
hexa
ne
wate
r
Befo
re e
xtrac
tion
hexa
ne
wate
r
Afte
r extr
actio
n
•For
co
nfirmat
ion
of
iden
tify
of
individu
al
aflato
xins
, tw
o dimen
sion
al TL
C de
velopm
ent
can
be
applied,
wh
ere
afte
r de
velopm
ent
in
firs
t so
lven
t, y
ou r
otat
e plat
e90
°C,
and
deve
lop
again
in s
ame
solven
t.
TLC
met
hods
are
sem
i-qu
antita
tive
bec
ause
the
y ar
e ba
sed
on m
atch
ing
inte
nsity
of f
luor
esce
nce
of
sample
extr
act
with
tho
se of
aflat
oxin
stan
dard
so
lution
s of
diffe
rent
con
cent
ration
s.
If
a Den
sito
met
er
is
used
, it
can
conv
ert
fluo
resc
ence
inte
nsity
of
sp
ots
(450
nm)
into
pe
aks.
For
optimum
quan
tifica
tion
, HPL
C us
ing
fluo
resc
ence
det
ecto
r is r
equire
d.
-Im
mun
oass
ays
Ant
ibod
ies
are
able
to
mak
e a
sign
ific
ant
cont
ribu
tion
to
cha
ract
eris
atio
nan
d qu
alit
y as
sess
men
t of
agr
i-foo
d m
ater
ials
. The
uni
que
prop
erti
es o
f an
tibo
dies
incl
ude
a po
tent
ial
for
extr
aord
inar
y di
vers
ity
of r
ecog
niti
on,
high
aff
init
y an
d sp
ecif
ity
towa
rds
the
targ
et,
and
a st
abili
ty a
nd r
obus
tnes
s we
ll-su
ited
to
in v
itro
(an
d ev
en 'i
n fi
eld'
) app
licat
ions
.
Imm
unoa
ssay
s ha
ve b
een
reco
gnis
edfo
r a
num
ber
of
prop
erti
es:
-per
form
ance
-spe
cifi
ty,
sens
itiv
ity,
pre
cisi
on,
accu
racy
an
d re
prod
uvib
ility
,-h
igh
rate
s of
sam
ple
thro
ugh-
put,
-dea
ling
with
ana
lyte
sdi
ffic
ult
to h
andl
e by
alt
erna
tive
pr
oced
ures
,-s
impl
icit
y
Mod
ern,
non
-isot
opic
met
hods
suc
h as
the
en
zym
e-lin
ked
imm
unos
orbe
ntas
say
(ELI
SA) h
ave
basi
c, c
ompa
rati
vely
che
ap e
quip
men
t re
quir
emen
ts.
Man
y of
the
app
licat
ions
of
imm
unoa
ssay
s in
the
ag
ri-f
ood
area
hav
e be
en r
elat
ed t
o fo
od s
afet
y.
Of
the
hapt
enic
com
poud
s, m
uch
inte
rest
has
be
en d
evot
ed t
o th
e m
ycot
oxin
s, t
he s
econ
dary
m
etab
olit
e m
old
prod
ucts
tha
t ca
n be
fou
nd a
s co
ntam
inan
ts in
foo
d an
d fe
ed a
nd w
hich
can
hav
e po
tent
tox
ic b
ioac
tivi
ties
in a
nim
als
and
man
.
Espe
cial
lyfo
rth
e tr
icho
thec
enes
, an
d th
e fu
mos
ins,
and
man
y ot
her
sim
ilar
low
mol
ecul
ar
weig
ht
mat
eria
ls,
incl
udin
g pe
stic
ides
, ph
ycot
oxin
san
d ve
teri
nary
dr
ugs,
im
mun
oche
mic
alm
etho
dsof
fer
a ve
rygo
odan
alys
isal
tern
ativ
e.
Als
o, f
orsp
ecif
icat
ion
of a
sam
ple
of m
eat,
im
mun
oass
ay
prov
ides
a
rapi
d,
sim
ple
and
obje
ctiv
e pr
oced
ure
that
is d
iffi
cult
to
repr
oduc
e wi
th a
lter
nati
ve m
etho
ds o
f an
alys
is.
EXA
MPL
E 3:
Fo
od
Add
itiv
es
(ie:C
olor
ants
-Foo
d dy
es)
Food
color
ants
are
eithe
r wa
ter
solubl
e [T
hese
being
ca
lled
(-N=N
-)“a
zody
es”
or "
coal t
ar d
yes”
], o
r o
il so
luble
like
the
natu
ral ca
rote
nes.
The
ir Q
ualit
ative
analys
is i
nvolve
eith
rer
dyeing
with
white
def
atte
d wo
ol (to
see
if
any
add
ed c
olor
ant
ispr
esen
t or
not
)or
for
iden
tifica
tion
of ind
ivid
ual dy
es,
pape
r o
r th
inlaye
rch
romat
ogra
phy
is p
erfo
rmed
. Fo
rth
isse
cond
purp
ose,
the
sample
solution
is s
pott
edto
geth
erwi
thst
anda
rdso
lution
sof
Ora
nge
S an
dAmar
anth
dyes
.
Aft
er d
evelop
men
tin 4
diffe
rent
deve
loping
solven
tsy
stem
s,
the
sample
spot
sob
serv
edin e
ach
are
tobe
co
ded
for
their
resp
ective
RF va
lues
obta
ined
afte
rde
veloping
in ea
chof
th
ere
spec
tive
solven
tsy
stem
sde
scribe
din n
ext
slid
e. C
oding
is a
s fo
llows
:
The
4 fo
llowi
ngdi
ffer
ent
solv
ent
syst
ems
are
used
for
the
deve
lopm
ents
:
1.Tri
sodi
umci
trat
e/H
2O/N
H4O
H2.
T-bu
tano
l/pr
opio
nic
acid
/wat
er3.
T.S.
cit
rate
/he
xane
/H2O
4.
Met
hyl p
ropa
nol/
wate
r/et
hano
l/N
H4O
H
Each
sam
ple
will
have
a fo
ur-le
tter
edco
de(s
eene
xtsl
ide)
:
Exam
ple:
ACD
D m
eean
sth
edy
ein
sam
ple
was
A
in s
olve
nt1,
C in
sol
vent
2, a
ndD
in s
olve
nts
3 an
d4
For
RF:
A)T
he s
pots
abo
ve o
rang
e S
B)Sa
me
Rfwi
th o
rang
e S,
abo
ve A
C)Be
low
oran
ge S
, abo
ve A
mar
anth
D)S
ame
Rfwi
th A
mar
anth
, abo
ve B
E)Be
low
amar
anth
Follo
wing
pro
per
iden
tifi
cati
ons
of t
he d
ye(s
) in
th
e f
ood
sam
ple,
the
ind
ivid
ual
dye
has
to b
e ex
trac
ted
and
stud
ied
for
quan
tita
tive
ev
alua
tion
s, u
sing
a
visi
ble
spec
trop
hoto
met
er,
by m
easu
ring
its
abs
orba
nce
valu
e at
its
pea
k va
lue
of
the
stan
dard
dyes
’ssp
ectr
um
and
com
pari
ng i
t to
tha
t of
sta
ndar
d dy
e so
luti
ons
on a
cal
ibra
tion
cur
ve p
repa
red
for
this
pur
pose
.