D ATE PERFORMED: A UGUST UGUST 29, 2008
EXPERIMENT NO. 9: S PECTROPHOTOMETRIC DETERMINATION OF IRON IN A QUEOUS QUEOUS SOLUTIONS AS A AS A C COMPLEX OF 1,10PHENANTHROLINE EAMILLO J.G.S J.G.S.. R EAMILLO EPARTMENT OF C D EPARTMENT C HEMICAL E NGINEERING, COLLEGE OF E E NGINEERING NIVERSITY OF NIVERSITY OF THE THE P HILIPPINES, D ILIMAN , QUEZON C HILIPPINES U C ITY , P
R ECEIVED 8, 2008 ECEIVED SEPTEMBER 8,
ABSTRACT The experimen !im" # $eermine he %#n%enr!i#n #& !n 'n(n#)n Fe*II+ "#'i#n -. '"in/ ! "pe%r#ph##meer !n$ !pp.in/ he 0eer1L!m-er2" L!)3 Ir#n*II+ )!" re!%e$ )ih 4,451phen!nhr#ine # pr#$'%e he %#mpex ri"*4,451phen!nhr#ine+ir# ri"*4,451phen!nhr#ine+ir#n*II+3 n*II+3 Fi6e %#mpex "!n$!r$ "#'i#n" "#'i#n" )ere '"e$ # #-!in ! %!i-r!i#n %'r6e . 7 53489: *x+ ; 535<54, re!i6e # ! re!/en -!n(, )ih ! %#rre!i#n &!%#r #& R = 7 5388<93 U"in/ hi" %'r6e, he %#n%enr!i#n #& he 'n(n#)n Fe*II+ "#%( "#'i#n )!" $eermine$ !n$ )!" &#'n$ # h!6e !n !6er!/ !6er!/e e #& >3?4 >3?4 ppm #r :3:9E1 :3:9E15< 5< m#e"@ m#e"@i ier er )i )ih h ! "!n$! "!n$!r$ r$ $e6i! $e6i!i# i#n n #& 535>53 535>53 H#)e6er )hen p##e$ #/eher )ih he #her /r#'p"2 $!!, he "!n$!r$ $e6i!i#n in%re!"e" # 5345, )hi%h mi/h -e $'e # he #)er %#n%enr!i#n 6!'e" #& /r#'p 92" $!! "e3 Q1e" "h#)e$ h! he "!i$ $!! "e )!" n# !n #'ier !n$ )!" "i in%'$e$ in he %!%'!i#n"3 %!%'!i#n"3 Err#r" mi/h h!6e -een %!'"e$ -. he in%#n"i"en%ie" in%#n"i"en%ie" in he %'6ee h!n$in/ !" )e !" -. he imi!i#n" #& 0eer2" !), i(e i#n iner!%i#n", )hi%h )ere n# !(en in# !%%#'n3
INTRODUCTION Spectrophotometr !" o#e o$ the mo"t commo# !#"tr%m r%me#t&' tech# ch#!(%e (%e" !# (%&#t!t&t!)e &#&'"!", *here!# the co#ce#tr&t!o# o$ & "o'%t!o# !" +eterm!#e+ me&"%r!#- the r&+!&#t e#er- &"ore+ & chem!c&' chem!c&' ""tem ""tem co#t&!#!#co#t&!#!#- the &#&'te &#&'te or !t" +er!)&t!)e. It !" po""!'e to +eterm!#e the &#&' &#&'t te e co#ce co#ce#t #tr&t r&t!o !o# # *!th *!th &ppr &pprec ec!& !&' 'e e &cc% &cc%r& r&c c &#+ &#+ prec! prec!"! "!o# o#,, e"pe e"pec! c!&' &'' ' !$ !t" !t" +er!)&t!)e +er!)&t!)e !" &# !#te#"e' !#te#"e' co'ore+ co'ore+ comp'e/ comp'e/ *h!' *h!'e e the the re&c re&ct& t&#t #t" " &re &re !# the the $orm $orm o$ "o'%t! "o'%t!o#" o#" *h!ch *h!ch &re co'or' co'or'e"" e"" or o$ 'e""er 'e""er co'or !#te#"!t, %"!#& "pectrophotometer. "pectrophotometer. Chr!"t!&#, 2001
m&t!c m&t!c r&+!&t r&+!&t!o# !o# !" !''%"t !''%"tr&t r&te+ e+ the the Beer3 Beer3 4&m 4&mer ert5 t5" " 4&*: 4&*: A 6 &c, &c, *her *here e A !" the the &"or&#ce, & !" the *&)e'e#-th3+epe#+e#t &"orpt!)!t coe7!c!e#t, !" the p&th 'e#-th, &#+ c !" the &#&'te co#ce#tr&t!o#. The Beer3 4&mert5" '&* co%'+ e emp'oe+ to "et%p & c&'! c&'!r r&t &t!!o# c%r) c%r)e e thro thro%%-h h & "er! "er!e" e" o$ "t&#+&r+ "o'%t!o#", *h!ch c&# the# e %"e+ to +eterm +eterm!#e !#e the %##o* %##o*# # co#ce# co#ce#tr& tr&t!o t!o#. #. Soo-, 2001
The proce+%re !" %"e$%' e"pec!&'' !# the the (%&# (%&#t! t!t& t&t! t!)e )e +ete +eterm rm!# !#&t &t!o !o# # o$ tr&c tr&ce e met&'" met&'",, '!e '!e FeII. eII. Iro#II Iro#II re&+!' re&+!' re&ct" re&ct" *!th ,03phe#&#thro'!#e C 28;2 to $orm &# !#te#" !#te#"e' e'3co' 3co'ore ore+ + re+3or re+3or&#&#-e e comp'e comp'e/, /, tr!",03phe#&#thro'!#e!ro#II, tr!",03phe#&#thro'! #e!ro#II, &" -!)e# E)er mo'ec%'&r &#&'te !" c&p&'e o$ the re&ct!o#: &"or!#cert&!# ch&r&cter!"t!c Fe2<&( < =C28;2 *&)e'e *&)e'e#-t #-th" h" o$ e'ectr e'ectrom& om&-#e -#et!c t!c r&+!&t! r&+!&t!o# o# +epe#+!#- o# !t" $%#ct!o#&' -ro%p". I# th!" FeC28;2=2<&( proc proce" e"", ", the the e#er e#er- - o$ the the r&+! r&+!&t &t!o !o# # !" tr&#" tr&#"$err $erre+ e+ tempor tempor&r! &r!' ' to the mo'ec% mo'ec%'e, 'e, 1
re"%'t!#- to & +ecre&"e !# the r&+!&t!o# !#te#"!t. S!m!'&r', *he# )!"!'e '!-ht p&""e" thro%-h & co'ore+ "o'%t!o#, & $r&ct!o# o$ !t !" &"ore+ the "o'%t!o#> the %#&"ore+ '!-ht !" the# tr&#"m!tte+ &#+ c&# e (%&#t!t&t!)e' me&"%re+ Soo- et &', 991.
The &"or&#ce re&+!#-" $or the co'ore+ comp'e/ c&# the# e %"e+ to (%&#t!$ the !ro#II co#ce#tr&t!o# thro%-h the pre3ot&!#e+ c&'!r&t!o# c%r)e.
Th!" e/per!me#t &!m" to +eterm!#e the !ro#II co#ce#tr&t!o# !# &(%eo%" A "pectrophotometer m&e" %"e o$ "o'%t!o# "&mp'e" thro%-h the th!" co#cept !# or+er to +eterm!#e the "pectrophotometr!c &#&'"!" o$ !t" co'ore+ &"or&#ce o$ & cert&!# "o'%t!o# comp'e/ tr!",03phe#&#thro'!#e!ro#II me&"%r!#- the tr&#"m!tte+ '!-ht re'&t!)e to & &#+ +emo#"tr&te the pr!#c!p'e" !#)o')e+ !# '&# "o'%t!o# %"e+ !# the c&'!r&t!o#. the "pectrophotometr!c metho+ o$ &#&'"!". The e/per!me#t &'"o &!m" to +emo#"tr&te The '!#e&r re'&t!o#"h!p et*ee# the pert!#e#t c&'c%'&t!o#" !# c&'!r&t!o# &#+ &"or&#ce &#+ &#&'te co#ce#tr&t!o# &" &#&'"!", !''%"tr&te the Beer34&mert5" 4&*, *e'' &" p&th 'e#-th $or mo#ochro3 &" *e'' &" &cco%#t $or the po""!'e +e)!&t!o#" $rom &#+ '!m!t&t!o#" o$ the &$oreme#t!o#e+ '&*. DATA AND RESULTS GROUP I GROUP II A. Absorption Spectrum A. Absorption Spectrum ?&)e'e#-th &t m&/!m%m &"orpt!o# @m&/: ?&)e'e#-th &t m&/!m%m &"orpt!o# @m&/: 509.80 ! 509.80 ! B. Calibration Curve B. Calibration Curve Co#ce#tr&t!o# o$ *or!#- "t+ FeII Co#ce#tr&t!o# o$ *or!#- "t+ FeII "o'%t!o#: "5 ##! "o'%t!o#: "5 ##! Table 1.1 Absorbance Readings rom Table ".1 Absorbance Readings rom Calibration Calibration Vo'%me o$ Co#ce#tr&t!o# A"or&# Vo'%me o$ Co#ce#tr&t!o# A"or& ?or!#o$ St&#+&r+ ce ?or!#o$ St&#+&r+ #ce St&#+&r+ FeII, St&#+&r+ FeII, So'%t!o#, m' ppm So'%t!o#, m' ppm .00 0. 0.1 .00 0. 0.2 2.00 .0 0.2 2.00 .0 0.2 =.00 . 0.=20 =.00 . 0.== 1.00 2.0 0.12 1.00 2.0 0.1=0 .00 2. 0.2 .00 2. 0.8 C. Sample Anal!sis C. Sample Anal!sis Vo'%me o$ "toc "&mp'e "o'%t!o#: Vo'%me o$ "toc "&mp'e "o'%t!o#: 00 m' 00 m' Vo'%me o$ &'!(%ot $rom "toc "o'%t!o#: Vo'%me o$ &'!(%ot $rom "toc "o'%t!o#: 0 m' 0 m' Vo'%me o$ +!'%te+ %##o*# "o'%t!o#: Vo'%me o$ +!'%te+ %##o*# "o'%t!o#: 0 m' 0 m' Table 1." Absorbance Readings rom Table "." Absorbance Readings rom Samples Samples U##o*# S&mp'e A"or&#ce U##o*# S&mp'e A"or&#ce ;%mer ;%mer 0.81 0.88 2 0.81 2 0.201 = 0.8= = 0.90 #. Tabulated Results #. Tabulated Results 4!#e&r e(%&t!o# o$ the c&'!r&t!o# c%r)e: 4!#e&r e(%&t!o# o$ the c&'!r&t!o# c%r)e: $ % 0."0&" '() $ % 0."05* '() + 2
+ 0.009 Corre'&t!o# F&ctor R 2: R " % 0.9999 Table 1.$ Calculated Concentration o Samples U##o* Co#ce#tr&t! Co#ce#tr&t!o# o$ # o# o$ FeII, FeII !# Stoc S&mp'e ppm So'%t!o# m-4 mo'e" ppm 4 M .1E3 0.812 1.2 0 2 .1E3 0.812 1.2 0 1 .19E3 0.8= 1.8 0 A/ &.5"E*."0 05
0.0095 Corre'&t!o# F&ctor R 2: R " % 0.998& Table ".$ Calculated Concentration o Samples U##o* Co#ce#tr&t! Co#ce#tr&t!o# o$ # o# o$ FeII, FeII !# Stoc S&mp'e ppm So'%t!o# m-4 mo'e" ppm 4 M .8E3 0.89 1.= 0 2 8.18E3 0.91 1.= 0 1 .8E3 0.89 1.=9 0 A/ 8.0*E*.*9 05
%igure 1. Group I Calibration Curve& %igure ". Group II Calibration Curve& Grap' o t'e Absorbance vs Grap' o t'e Absorbance vs Concentration o t'e comple( tris)1*1+, Concentration o t'e comple( tris)1*1+, p'enant'roline-iron)II- at ma( / 0+.2+ p'enant'roline-iron)II- at ma( / 0+.2+ nm nm GROUP III GROUP I3 A. Absorption Spectrum A. Absorption Spectrum ?&)e'e#-th &t m&/!m%m &"orpt!o# @m&/: ?&)e'e#-th &t m&/!m%m &"orpt!o# @m&/: 510.00 ! 509.*0 ! B. Calibration Curve B. Calibration Curve Co#ce#tr&t!o# o$ *or!#- "t+ FeII Co#ce#tr&t!o# o$ *or!#- "t+ FeII "o'%t!o#: "5 ##! "o'%t!o#: "5 ##! Table $.1 Absorbance Readings rom Table 4.1 Absorbance Readings rom Calibration Calibration Vo'%me o$ Co#ce#tr&t!o# A"or&# Vo'%me o$ Co#ce#tr&t!o# A"or& ?or!#o$ St&#+&r+ ce ?or!#o$ St&#+&r+ #ce St&#+&r+ FeII, St&#+&r+ FeII, So'%t!o#, m' ppm So'%t!o#, m' ppm .00 0. 0. .00 0. 0.= 2.00 .0 0.29 2.00 .0 0.2= =.00 . 0.=2= =.00 . 0.=1 1.00 2.0 0.12 1.00 2.0 0.110 .00 2. 0.2 .00 2. 0.28 C. Sample Anal!sis C. Sample Anal!sis Vo'%me o$ "toc "&mp'e "o'%t!o#: Vo'%me o$ "toc "&mp'e "o'%t!o#: 3
00 m' 00 m' Vo'%me o$ &'!(%ot $rom "toc "o'%t!o#: Vo'%me o$ &'!(%ot $rom "toc "o'%t!o#: 0 m' 0 m' Vo'%me o$ +!'%te+ %##o*# "o'%t!o#: Vo'%me o$ +!'%te+ %##o*# "o'%t!o#: 0 m' 0 m' Table $." Absorbance Readings rom Table 4." Absorbance Readings rom Samples Samples U##o*# S&mp'e A"or&#ce U##o*# S&mp'e A"or&#ce ;%mer ;%mer 0.90 0.9 2 0.92 2 0.9= = 0.9 = 0.9 #. Tabulated Results #. Tabulated Results 4!#e&r e(%&t!o# o$ the c&'!r&t!o# c%r)e: 4!#e&r e(%&t!o# o$ the c&'!r&t!o# c%r)e: $ % 0."02* '() $ % 0.19* '() + + 0.0159 0.0501 Corre'&t!o# F&ctor R 2: R " % 0.999& Corre'&t!o# F&ctor R 2: R " % 0.995* Table $.$ Calculated Concentration o Table 4.$ Calculated Concentration o Samples Samples U##o* Co#ce#tr&t! Co#ce#tr&t!o# o$ U##o* Co#ce#tr&t! Co#ce#tr&t!o# o$ # o# o$ FeII, FeII !# Stoc # o# o$ FeII, FeII !# Stoc S&mp'e ppm So'%t!o# S&mp'e ppm So'%t!o# m-4 mo'e" m-4 mo'e" ppm 4 M ppm 4 M .E3 .E3 0.8 1.28 0 0.1 =.2 0 2 .E3 2 .E3 0.8 1.== 0 0.=1 =. 0 1 .E3 1 .E3 0.8 1.=0 0 0.1 =.2 0 A/ &.&1E A/ .*E*.20 05 2.&1 05
%igure $. Group III Calibration Curve& %igure 4. Group I3 Calibration Curve& Grap' o t'e Absorbance vs Grap' o t'e Absorbance vs Concentration o t'e comple( tris)1*1+, Concentration o t'e comple( tris)1*1+, p'enant'roline-iron)II- at ma( / 01+.++ p'enant'roline-iron)II- at ma( / 0+.4+ nm nm
DISCUSSION
to me&"%reme#t" ot&!#e+ mo#ochrom&t!c r&+!&t!o# "!#ce !t"
$rom '!#e&r 4
I# or+er $or & "pec!e" to e )!&'e $or "pectrophotometr!c +eterm!#&t!o#, !t m%"t e/h!!t r&+!&t!o# &"orpt!o#. o*e)er !# the &"e#ce o$ "%ch ch&r&cter!"t!c", & r&+!&t!o# &"or!#+er!)&t!)e m!-ht e %"e+. Chr!"t!&#, 2001 A(%eo%" !ro#II re&ct" re&+!' *!th ,03phe#&#thro'!#e to $orm & re'&t!)e' "t&'e re+3or&#-e tr!",03 phe#&#thro'!#e!ro#II comp'e/. The corre"po#+!#- pro+%ct3$&)ore+ re&ct!o# !" -!)e# the chem!c&' e(%&t!o#: F"3'4) 3 2C1"H8N" F'C1"H8N")2"3'4) The co'or !#te#"!t o$ the re+3or&#-e comp'e/ !" re'&t!)e' h!-h e)e# !# +!'%te "o'%t!o#", m&!#!t "%!t&'e $or "pectrophotometr!c &#&'"!" T*!--, 92. o*e)er, !# the "pectrophotometr!c +eterm!#&t!o# o$ the co#ce#tr&t!o# o$ !ro#II, mere &"or&#ce re&+!#-" *o%'+ e !#co#c'%"!)e *!tho%t the &pp'!c&t!o# o$ the Beer34&mert5" 4&*. Accor+!#- to the Beer34&mert5" 4&*, $or & mo#ochrom&t!c r&+!&t!o#, the &"or&#ce o$ & "o'%t!o# !" +!rect' proport!o#&' to the co#ce#tr&t!o# o$ the &"or!#- "pec!e" &#+ the p&th 'e#-th o$ the &"or!#- me+!%m *!th "ome proport!o#&'!t co#"t&#t &, c&''e+ the *&)e'e#-th3+epe#+e#t &"orpt!)!t coe7!c!e#t. The '&* !" e"t !''%"tr&te+ the e(%&t!o#: A 6 &c, *here A !" the &"or&#ce, &, the *&)e'e#-th3+epe#+e#t &"orpt!)!t coe7!c!e#t> , the p&th 'e#-th, &#+ c !" the &#&'te co#ce#tr&t!o#. A'tho%-h tr&#"m!tte+ '!-ht !" the o#e e!#- +!rect' me&"%re+ the "pectrophotometer5" +etector, Beer5" '&* !" e/pre""e+ !# term" o$ &"or&#ce !# or+er to pre"er)e the '!#e&r re'&t!o#"h!p et*ee# the '!-ht3+er!)e+ (%&#t!t &#+ the &#&'te co#ce#tr&t!o#, *h!ch *!'' pro)e to e )er %"e$%' !# the "ett!#-3%p o$ the c&'!r&t!o# c%r)e. A'tho%-h the Beer34&mert re'&t!o#"h!p o$ &"or&#ce &#+ co#ce#tr&t!o# !" )er %"e$%' !# +eterm!#!#- the %##o*# co#ce#tr&t!o# o$ "o'%t!o#" -!)e# the &"or&#ce re&+!#-" o$ & "pectrophotometer, !t h&", !# !t"e'$, & co%p'e o$ '!m!t&t!o#" Sooet &', 2001. The Beer34&mert5" '&* ho'+" tr%e o#' $or co#ce#tr&t!o#" 'o*er th&# 0.0 M. At co#ce#tr&t!o#" h!-her th&# 0.0 M, the &)er&-e +!"t&#ce" et*ee# !o#" or mo'ec%'e" &re 'e""e#e+ "%ch th&t e&ch p&rt!c'e &7ect"
e(%&t!o# +oe" #ot &cco%#t $or po'chrom&t!c '!-ht. Gr&t!#-" or 'ter" &re re(%!re+ to "et the r&+!&t!o# to & &#+ o$ *&)e'e#-th" #e&r the t&r-et *&)e'e#-th *here the '&* *o%'+ e &pp'!c&'e Soo- et &', 2001. I# the e/per!me#t, the !ro#II *&" #ot tre&te+ *!th ,03phe#&#thro'!#e &'o#e> & co%p'e o$ re&-e#t" *ere &++e+ e$ore &#+ &$ter to m&!#t&!# the #ece""&r co#+!t!o#" $or &# opt!m%m re&ct!o# ""tem. For the c&'!r&t!o# "et%p, "!/ +!7ere#t co#ce#tr&t!o#" o$ !ro# *ere prep&re+, "t&rt!#- *!th the re&-e#t '&#, the o#e *!th &'' the re&-e#t" e/cept the "pec!e" to e &#&'e+ &#+ !" &'"o #o*# &" the o#e *!th H0 ppm5 co#ce#tr&t!o#. The #e/t )e "o'%t!o#", #&me', 0., .0, ., 2.0, &#+ 2. ppm, *ere m&+e !# !#creme#t" o$ 0. ppm *!th re"pect to the re&-e#t '&c. E)e#' "p&ce+ !#creme#t" *ere %"e+ !# or+er to -et co#)e#!e#t )&'%e" !# the c&'!r&t!o# c%r)e &" *e'' &" to e#h&#ce the prec!"!o# o$ the e(%&t!o# $or the '!#e&r re-re""!o# to e %"e+. The "!/ "et%p" *ere the# tre&te+ *!th h+ro/'&m!#e h+roch'or!+e !# or+er to re+%ce &'' the FeIII !# the "o'%t!o# !#to the +e"!re+ &#&'te, FeII, &#+ eep them !# the FeII "t&te. The chem!c&' re&ct!o# !" -!)e# the $o''o*!#- e(%&t!o#: *F23 3 "NH"OHHC6 * F"3 3 N"O 3 *H3 3 H"O The "o'%t!o#, *h!ch or!-!#&'' h&" o#' FeII !# !t, m!-ht h&)e tr&ce" o$ FeIII "!#ce FeII h&" & te#+e#c to e o/!+!e+ !# the pre"e#ce o$ *&ter &#+ &c!+!c me+!&. Co#)er"!o# o$ )!rt%&'' &'' FeIII !#to FeII !" #ece""&r to $&c!'!t&te -oo+ comp'e/ $orm&t!o#. The #e/t "tep !# the "et%p prep&r&t!o# !" the &++!t!o# o$ e/ce"" ,03phe#&#thro'!#e. The FeII *&" the '!m!t!#- re&-e#t $or &'' the "t&#+&r+ "o'%t!o#"> o#' "m&'' $r&ct!o#" o$ the 2 ppm *or!#- "t&#+&r+ *&" %"e+, &" comp&re+ *!th the 0.20J *) co#ce#tr&t!o# o$ the ,03phe#&#thro'!#e $or the "t&#+&r+" . The $or*&r+ re&ct!o# *&" &""%me+ to h&)e procee+e+ comp'ete', 'e&)!#- #o FeII !o# eh!#+. Co#"e(%e#t', the tr!",03 phe#&#thro'!#e!ro#II comp'e/ co#ce#tr&t!o# *&" co#"!+ere+ e(%&' to the co#ce#tr&t!o# o$ the '!m!t!#- re&-e#t, FeII. Mo"t re&ct!o#" o$ the "&me &$oreme#t!o#e+ re&ct!o# ""tem" *!th &ppro/!m&te' e(%!mo'&r re&ct&#t" +o #ot -o !#to 5
the ch&r-e +!"tr!%t!o#, &#+ co#"e(%e#t', the &"orpt!o# o$ #e&r p&rt!c'e", re"%'t!#- to +e)!&t!o#" $rom !t" '!#e&r #&t%re Soo- et &', 2001. Mo'&r &"orpt!)!t o$ the &#&'te !" &'"o &'tere+ *he# p&rt!c'e" &#+ e'ectro'te" !#ter&ct e'ectro"t&t!c&'', 'e&+!#- to $%rther +ep&rt%re" $rom the '!#e&r #&t%re o$ the Beer5" '&*. Th!" occ%r" *he# the "o'%t!o# h&" & re'&t!)e' h!-h co#ce#tr&t!o# o$ !#ter$er!#"pec!e", e"pec!&'' e'ectro'te", "!#ce Beer5" 4&* +oe" #ot &cco%#t $or "pec!e" %#+er-o!#+!""oc!&t!o#, &""oc!&t!o#, &#+ re&ct!o# *!th the "o')e#t Soo- et &', 2001. A#other '!m!t&t!o# o$ Beer5" '&* !" th&t !t &pp'!e" o#'
comp'et!o#> the '!m!t!#- re&-e#t !" #ot comp'ete' tr&#"$orme+ !#to the pro+%ct. B%t "!#ce the L,03phe#&#thro'!#eNN *&" m%ch -re&ter th&# th&t o$LFeII, there *&" &# e/ce"" L,03phe#&#thro'!#e !# the "o'%t!o#. The 4e Ch&te'!er5" pr!#c!p'e e#"%re+ th&t the e/ce"" L,03phe#&#thro'!#e *o%'+ p%"h the $or*&r+ re&ct!o# $%rther, th%" co#)ert!#- &'' the FeII !#to tr!",03 phe#&#thro'!#e!ro#II ?h!tte# et &', 200.
The '&"t re&-e#t to e &++e+ *&" the &cet&te %7er *!th p 1. The re&ct!o# ""tem #ee+" to e %7ere+ *!th!# the "&!+ p r&#-e to $&c!'!t&te the $%'' co'or +e)e'opme#t o$ the comp'e/ &#+ #e%tr&'!e the < $rom the o$ the h+ro/!+e o$ !ro#, *h!ch co%'+ po""!' &$oreme#t!o#e+ re&ct!o# o$ Fe=< *!th 'e&+ to +e)!&t!o#" $rom the &ct%&' FeII h+ro/'&m!#e h+roch'or!+e. Moreo)er, the co#ce#tr&t!o#". %7er "o'%t!o# *o%'+ pre)e#t the $orm&t!o# the error" +%e to !#ter$er!#- co#t&m!#&#t" It !" there$ore #ece""&r to &++ e&ch $rom the e/per!me#t re&-e#t" &#+ )e""e'", re&-e#t &ccor+!#- to the "e(%e#ce me#t!o#e+ &#+ the &"or&#ce re&+!#-" *o%'+ &o)e to e#"%re the comp'ete re&ct!o# o$ corre"po#+ to the tr!",03 !ro#II *!th ,03phe#&#thro'!#e, to m!#!m!e phe#&#thro'!#e!ro#II co#ce#tr&t!o# *!th the po""!!'!t o$ !#ter$er!#- !o#" '!e !ro#III m!#!m&' 'o"" o$ &cc%r&c &#+ prec!"!o#. &#+ h+ro/!+e", &#+ to ot&!# opt!m%m comp'e/ &"or&#ce re&+!#-". The rem&!#!#- )e "o'%t!o#"5 &"or&#ce" *ere the# ot&!#e+ o#e &$ter A$ter &'' "o'%t!o#" h&)e ee# prep&re+, &#other %"!#- the "pectrophotometer, re'&t!)e the #e/t "tep *&" to c&'!r&te the to the '&# "o'%t!o#. "pectrophotometer &ccor+!#to the co#+!t!o#" #ece""&r $or the FeII The &"or&#ce re&+!#-" $rom the )e +eterm!#&t!o#. "o'%t!o#" *ere the# %"e+ to "et%p the c&'!r&t!o# c%r)e %"!#- '!#e&r re-re""!o#. A S!#ce the comp'e/ tr!",03 c&'!r&t!o# c%r)e !" #ee+e+ "!#ce the phe#&#thro'!#e!ro#II !" the &"or!#- &"orpt!)!t co#"t&#t !" #ot &'*&" & #o*# "pec!e", the "pectrophotometer *&" "et to & (%&#t!t, &#+ m& )&r $rom o#e "et%p to *&)e'e#-th r&#-e o$ =0 to 00 #mK& r&#-e &#other. A c&'!r&t!o# c%r)e o$ $ % 0.19* *here the re+ or&#-e comp'e/ c&# e/h!!t '() + 0.0501 *!th & corre'&t!o# $&ctor o$ R " &"orpt!o# o$ -ree# '!-ht. % 0.995* *&" ot&!#e+ p'ott!#- the &"or&#ce &-&!#"t the co#ce#tr&t!o#. I#tere"t!#-', the tr!",03 phe#&#thro'!#e!ro#II comp'e/ !" co'ore+ The c&'!r&t!o# c%r)e +er!)e+ $rom the re+ #ot ec&%"e the comp'e/ &"or" re+ e/per!me#t *&" & '!#e&r e(%&t!o# o$ the Beer3 r&+!&t!o#, %t ec&%"e !t &"or" !t" 4&mert5" '&*. The compo#e#t corre"po#+" comp'eme#t&r co'or, -ree#. The -ree# to the &"or&#ce, the "'ope m to the pro+%ct r&+!&t!o# !" the o#e th&t e/per!e#ce" o$ &"orpt!)!t &#+ p&th 'e#-th, &, &#+ the / m&/!m%m &"or&#ce ch&#-e *!th re"pect to compo#e#t to the co#ce#tr&t!o# c: co#ce#tr&t!o#, *h!'e the re+ r&+!&t!o# !" 6 m/ < &'mo"t %#&'tere+, re"%'t!#to !t" A 6 &c tr&#"m!""!o#. The tr&#"m!""!o# o$ re+ '!-ht &#+ the &"orpt!o# o$ -ree# '!-ht !" the o#e The c&'!r&t!o# c%r)e *&" the# %"e+ to th&t -!)e" the tr!",03 c&'c%'&te the co#ce#tr&t!o# o$ the %##o*# phe#&#thro'!#e!ro#II comp'e/ !t" "&mp'e" p'%--!#- !# the!r &"or&#ce +!"t!#ct!)e co'or. )&'%e !# the c&'!r&t!o# c%r)e. So')!#- $or , 6
U"!#- the mo"t co#ce#tr&te+ FeII "o'%t!o#, "pectr&' "c&##!#*&" the# emp'oe+ to +eterm!#e the '&m+& m&/ &#+ the &"e'!#e o$ the &"orpt!o# "pectr%m. The '&m+& m&/ corre"po#+" to the &"or&#ce *&)e'e#-th *!th m&/!m%m "e#"!t!)!t. The @m&/ corre"po#+" to the &"orpt!o# pe& o$ the "o'%t!o# *here!# the "e#"!t!)!t ch&#-e !# &"or&#ce per %#!t ch&#-e o$ co#ce#tr&t!o# !" h!-he"t. Moreo)er, the corre"po#+!#- &"orpt!o# c%r)e !" o$te# &t &t & m&/!m%m, *h!ch $&c!'!t&te" & -oo+ &+here#ce to the Beer34&mert5" '&* &#+ 'e"" %#cert&!#t +%e to prec!"e repro+%ct!o# $&!'%re" !# the *&)e'e#-th "ett!#- o$ the !#"tr%me#t Soo-, et &', 991. O# the other h&#+, the "pectr&' "c&##!#- !" #ot co#cer#e+ !# +eterm!#!#- the &"o'%te )&'%e $or & m&/!m%m> !t pert&!#" to & m&/!m%m )&'%e re'&t!)e to & re$ere#ce po!#t, the &"e'!#e, !# & "!m!'&r *& th&t &"or&#ce !" #ot &# &"o'%te (%&#t!t %t !" re'&t!)e to & re$ere#ce po!#t #o*# &" the '&#. ?he# the "pectrophotometer *&" "et to the @m&/, *h!ch, !# the $o%r e/per!me#t "et%p", $e'' et*ee# 09.10 0.00 #m, the c&'!r&t!o# proce+%re *&" e-%#. The r"t "tep *&" to c&'!r&te the "pectrophotometer &ccor+!#- to the '&# "o'%t!o# th&t *&" prep&re+. The prep&re+ '&# "o'%t!o# co#t&!#e+ &'' the re&-e#t" &#+ "o')e#t" e/cept $or the &#&'te, *h!ch !# th!" c&"e, *&" the FeII. A'' #ece""&r "tep" *ere &'"o per$orme+ o# the '&# "o'%t!o#, *h!ch *!'' e %"e+ to correct the "pectrophotometr!c me&"%reme#t". The c&'!r&t!o# *!th the '&# "o'%t!o# *o%'+ e'!m!#&te the h!-her co#ce#tr&t!o#", #-erpr!#t" o# the c%)ette +%r!#- '&# "o'%t!o# c&'!r&t!o# co%'+ !e'+ to & 'o*er &"or&#ce re&+!#- $or the "%ccee+!#- "t&#+&r+".
the co#ce#tr&t!o# o$ the three "o'%t!o#" $rom o#e %##o*# "&mp'e *&" $o%#+ to e 0.1, 0.=1, &#+ 0.1 ppm, re"pect!)e'. o*e)er, the"e co#ce#tr&t!o#" &re $or the +!'%te+ "o'%t!o#". I# or+er to +eterm!#e the co#ce#tr&t!o# o$ the "toc "o'%t!o#, the ot&!#e+ co#ce#tr&t!o# m%"t e m%'t!p'!e+ the +!'%t!o# $&ctor, *h!ch !# th!" c&"e, !" . To co#)ert th!" correcte+ ppm co#ce#tr&t!o# o$ the "toc "o'%t!o# !#to mo'&r!t, the co#ce#tr&t!o#" m%"t e +!)!+e+ 000 &#+ the mo'&r m&"" o$ FeII, *h!ch !" .81 -mo'. The reporte+ ppm )&'%e" $or the FeII %##o*# "toc "o'%t!o# *ere =.2, =., &#+ =.2, *!th &# &)er&-e o$ =. ppm. The mo'&r!t co%#terp&rt" ho*e)er *ere .E3 0, .E30, .E30 M re"pect!)e', *!th & me&# o$ .1E30 M. The re'&t!)e "t&#+&r+ +e)!&t!o# $or the "&!+ "et o$ +&t& *&" o#' &o%t 8.0 ppt *!th "t&#+&r+ +e)!&t!o# 0.0=0 "ee &tt&che+ c&'c%'&t!o# "heet, *h!ch me&#" & 'o* "c&tter!#- o$ the +&t& ot&!#e+. o*e)er, *he# poo'e+ to-ether *!th the +&t& o7 &'' $o%r -ro%p", the poo'e+ "t&#+&r+ +e)!&t!o# r!"e" to 0.08, pro&' ec&%"e -ro%p 15" co#ce#tr&t!o#" &re 'o*er th&# th&t ot&!#e+ &'' the other -ro%p". o*e)er, Q3 te"t +eterm!#e+ th&t the me&# o$ -ro%p 15" +&t& c&##ot e co#"!+ere+ &" &# o%t'!er. ≈
Po""!'e "o%rce" o$ error m!-ht e the pre"e#ce o$ #-erpr!#t" o# the "%r$&ce o$ the c%)ette +%r!#the c%)ette h&#+'!#-. A'tho%-h #-erpr!#t" !# the "t&#+&r+ "o'%t!o#" *!'' !e'+ h!-her &"or&#ce re&+!#-" &#+ co#"e(%e#t'
!# *&ter "&mp'e", !ro# +eterm!#&t!o# !# 'oo+ "&mp'e", &#+ &#&'"!" o$ met&' &#+ m!#er&' co#te#t !# $oo+ &#+ me+!c!#e". REFERENCES
Error" c&# &'"o re"%'t $rom the !#co#"!"te#c!e" o$ the "o'%t!o# )o'%me" %"e+, *h!ch c&# e ro%-ht &o%t &+he"!o# o$ "o'%t!o# mo'ec%'e" to the co#t&!#er"5 -'&"" "%r$&ce". A 'ot o$ '!(%!+ tr&#"$er *&" emp'oe+ !# the e/per!me#t, *h!ch co%'+ !e'+ to compo%#+e+ error. Error" !# the c&'!r&t!o# c%r)e c&# &'"o -re&t' &7ect the co#ce#tr&t!o# o$ the %##o*# "&mp'e". S!#ce &"or&#ce *&"
LSoo-, D.A., ?e"t, D.M., &#+ F.. o''er. A#&'t!c&' Chem!"tr: A# I#tro+%ct!o#. th e+. S&%#+er" Co''e-e P%'!"h!#-. USA. 991. L2Soo-, D.A, ?e"t, D.M., o''er, F.., &#+ S. R. Cro%ch. F%#+&me#t&'" o$ A#&'t!c&' Chem!"tr. 8th e+. Thom"o# Broo" Co'e, Thom"o# 4e&r#!#-, I#c. USA. 2001 L=T*!--, M. V. A(%&t!o# o$ Tr!",03 7
+er!)e+ $rom tr&#"m!tt&#ce, & )&'%e &"e+ o# the 'o-&r!thm!c re'&t!o#"h!p o$ '!-ht !#te#"!t, "'!-ht +!"crep&#c!e" c&# t&e !t" to'' o# the c&'!r&t!o# c%r)e, *h!ch c&# 'e&+ to po""!'e 'o"" o$ &cc%r&c &#+ prec!"!o#.
CONCLUSION AND RECOMMENDATION'S)
phe#&#thro'!#e!ro#II !# Ac!+ So'%t!o#. o%r#&' o$ Chem!c&' E+%c&t!o#. Vo'%me 19, ;%mer , M& 92 L1 Dem!rh&#, ;. &#+ E'm&'! F. T. Spectrophotometr!c Determ!#&t!o# o$ Iro#II *!th 3;!tro33&m!#o3,03 phe#&#thro'!#e. T%r Chem. 200= L?h!tte#, .?., D&)!", R.E., Pec, M.4., St&#'e, G.G. Chem!"tr. 8th e+. Thom"o# Broo"Co'e, CA, U.S.A. 200. pp. 32 LChr!"t!&#, G.D. A#&'t!c&' Chem!"tr. th e+. oh# ?!'e &#+ So#", I#c. U.S.A. 2001 L&rr!", D.C. Q%&#t!t&t!)e Chem!c&' A#&'"!". th e+. ?.. Freem&# &#+ Comp&#, ;e* or, U.S.A.
The co#ce#tr&t!o# o$ &# %##o*# FeII "&mp'e c&# e +eterm!#e+ thro%-h "pectrophotometr. I# the e/per!me#t, FeII *&" re&cte+ *!th ,03phe#&#thro'!#e to pro+%ce &# &"or!#- comp'e/ tr!",03 phe#&#thro'!#e. The +!7ere#t comp'e/ "t&#+&r+ "o'%t!o#" *ere the# %"e+ to come %p *!th & c&'!r&t!o# c%r)e re'&t!)e to the re&-e#t '&# *h!ch *&" "!m!'&r to the '!#e&r re'&t!o#"h!p o$ &"or&#ce &#+ co#ce#tr&t!o# &" -!)e# the Beer 4&mert5" 4&*: A 6 &c. APPENDIX The c&'!r&t!o# c%r)e ot&!#e+, 6 0.91 / 0.00 *!th & corre'&t!o# $&ctor o$ R 2 6 0.991, *&" %"e+ to c&'c%'&te the co#ce#tr&t!o# o$ the %##o*# "&mp'e &"e+ o# !t" &"or&#ce. C&'c%'&t!o#" "ho*e+ th&t the %##o*# FeII "toc "o'%t!o# h&" &# &)er&-e co#ce#tr&t!o# o$ =. ppm, or .1E3 0 M mo'e" per '!ter. The "t&#+&r+ +e)!&t!o# ot&!#e+ $or the -ro%p 1 "et%p *&" ro%-h' 0.0=0 %t *he# poo'e+ to-ether *!th &'' the other -ro%p", !#cre&"e+ to 0.08.
A. 7ORING EQUATIONS M V 6 M2 V 2 6 m/ < C&'!r&t!o# C%r)e, A 6 c See &tt&che+ +&t& "heet B. SAMPLE CALCULATIONS See &tt&che+ +&t& "heet &#+ e/ce' "heet
More "o'%t!o#" $or the "t&#+&r+ "&mp'e" *o%'+ -re&t' !#cre&"e the &cc%r&c o$ the c&'!r&t!o# c%r)e. M%'t!p'e !+e#t!c&' c%)ette" co%'+ !mpro)e the &"or&#ce re&+!#-" "!#ce repet!t!o# o$ the c%)ette !" pro#e to "cr&tch &#+ mo!"t%re %!'+3%p.
APPLICATIONS Spectrophotometr &#+ the Beer3 4&mert5" '&* &re %"e$%' co#cept" !# the +eterm!#&t!o# o$ the co#ce#tr&t!o# o$ co'ore+ "o'%t!o#", e"pec!&'' comp'e/e". The pro)!+e more &cc%r&te re"%'t" th&# )!"%&' &#+ m&#%&' t!tr&t!o# &#+ !" re'&t!)e' e&" to emp'o o#ce the "o'%t!o#" &re prep&re+. Spectrophotometr #+" & 'ot o$ &pp'!c&t!o#" !# !#+%"tr!e" &#+ me+!c!#e, '!e the &#&'"!" o$ tr&ce met&' !o#"
8
