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Quantitative chromatographic analysis using rectified radio frequency methods
AXALYTICA
QUANTITATIVE RECTIFIED PART
II.
CHIMICA
ACTA
CHROMATOGRAPHIC RADIO FREQUENCY
FLUORIDE,
CHLORIDE.
265
ANALYSIS USING METHODS
BROMIDE
.9ND
IODIDE
IWTRODUCTION
In ;in earlier publication 1 the quantitative analysis of mixtures of lithium, sodium and potassium ions by chromnto@aphic and radio-frequency techniques has been described. In this paper the method is cstendccl to the l1alidc ions. The tcchniquc is as follows. Fluoride, chloride, bromide and iodide present as their sodium salts are separated by paper chromatography using a new solvent mixture. The separated zones are cletectcd lq* the radio-frequency mcthocl of I~LAKE~. The bands arc then cut out and the salt present is extracted from the paper with a known volume of water. The impedances of the solutions so obtained arc tl1en measured and compared with those of standard solutions prepared in the same way. The impedance measurements arc made by means of UI,AKE’S conductimetric tub@. ESPERIIIENTAI,
Materials Tl~e analytical grade quality sodium salts were usccl, the fluoriclc and chloride being driecl and weighed directly. The bromide was standardised by the Mohr titration mctl1od3 and the iodide solution by titration with standard potassium ioclatc4. The solutions were made up with distilled water and contained the following amounts of haliclc ion per x00 ml: fluoride, 1.847 6; cllloride, 2.331 g; bromide, 1.516 g; iodide, I.g8g 6. Whatman No. 3 chromatography paper (cut in strips 2.6 x 60 cm) was foung satisfactory. The solvent consisted of a 4:2:x mixture (by volume) of acetone, pyriclinc and water, ancl the organic constituents were used without further purification. The chromatographic separation was carried out in large glass tubes which accommodated two chromatograms per tube. Method Tl1e solutions were placed on a pencil line 2.6 cm from the lower end of the paper by means of an A& micrometer syringe (Burrougl1s Wellcome and Co. London). The range covered was from 0.2-2 mg of halide ion. For each quantity, 20 chromatograms were prepared, 4 being of the mixed 11alides and ‘4 each of the individual halides to * Present address: Chemistry IDcpartment, University of Qucenshnd,
St. Lucia, Brisbane.
Anal. C/rim. Ada, 2d (1962) 265-268
266
J.
A.
RROOMHEAD,
N.
A.
GIBSON
provide the standards. The papers were suspcnclecl from hooks in the chromatography tubes and the ends immersed in the developing solvent to a depth of about I cm. After 24 11the solvent front had moved at least 44 cm up the paper. The slight colouration present in the pyridine of the solvent moved with the solvent front and so provided a permanent recd. of the distance moved. The chromatograms wcrc dried,
‘I’A
131.I’
1
.__. SltrurIicrrI
‘I,,
lirrur
.“_ I~lIIcJritlc l’lIl(Jritlc I~lIIcJrirlc ITI uoritlc lFluoriIlc I~lricwitlc I;IuoriIlc
2;
Clll(Jritk Cl~loritlc Chk’ritlc Chloritlc Clilorirlc Cliloritlc Cliloritlc
H 20
7.5 H‘!
1.73 .!.(I0
4 -’ I 3 .. I I .: I
0.1v
<
.5‘l
O.*=j.!
’ .3x I .7.! l .CJCJ
7’ ‘2
.‘) O.() 10. I Ij.0 IO.0 I ‘)..I ‘L..I .I.”
.-
7. I l.H 13.0 15.x IO.5
.
0.13 0.4.5 O..YIJ I .I 3 I .LO I .fIfj I .CJl 0.S’
’
0.77 I .o., ’ .‘I7 I .72 L *of->
I
4 I
0.7() I .“7
3.5 4.5 S-1 C’ I
Ic’tlith! Iotlitlc IotlitlI! I otliclc I t diclc
I cditlu - __.
‘J.5
0.52 O.S(’ I.13 I .#I”
.I2
lhunitlc I~rI’niiIlc lb’niitlc I~romitlc 1%oniidc I4rc~rnitlc 14rI~Iiiitl~!
I
0.20
3 .! I
._.
tllen conclitioncd for 30 inin in ;ui d.mosl~licrc of rclativc humidity itbOllt c~o”/~ to facilitate finding the bands dth the zone clctcrctor. Alter cutting out, the spots were CStrilctctl with 25 ml of clistillccl w;ltcr. ‘I’lic resulting solutions wcrc illlO\VCd to collie to tclnpcrnture in a COllStiLllt teinpcraturc bath (20 :I: o.:s’) and their impeclanccs then for tlic ioclitlc and bromide measured wit11 the concluctimetric tube. Tllc ITidilIgS solutions wcrc t:ikcn with iL gi~lVnliO~lcter (sensitivity 7.3 mm per ,tcA). For the more conccntratccl chloride ant1 fluoriclc solutions iL less scnsitivc microammetcr could hc cmployccl. The calibration curves were constructed by plotting the mctcr readings against quantity of ion prcscnt for the standards, and the unknowns then rend off from the graphs. The results obtninctl are given in Tnblc I.
QUASTITATIVE
CHIIOJXATOGI~APHIC
267
ANALYSIS
DISCUSSlOS
Consideration
of the results
leads to the following:rangc
of the nnnlyses:
171uoriClc
0.50~-1.00
~'hloridc
o.*jo-2.00
I
I3roniitlc
CJ._50-."."O
fJ
0.50--2.“O
3
Icxlitlc .._. ..-...
_-
.__
2
_ _
It is rcasonoblc that the fluoride and chloriclc analyses should lx the more accurate, since for a given volume they gave solutions of the grcntcr molarity. All other errors bcing equal, the greater the molarity the greater the meter readings, with consccluent tlic fluoride and cliloridc gave sliat-per bnncls on the incrcasetl accuracy I. Furtlicr, paper and so wcrc more rcaclily locntert. The following diagram (Fig. I) shows iL typical separation curve for npprosi~natel~ I-mg il~llOLlrltS ol each lialiclc ion.
CI’(1.3mg)
F ‘4, 60E Y L 40r”
I’ (1.0 mg) -.
I
5
10
15 Distanke
Fig.
x. Typical
‘I’llc bromitlc
ZUIIC &:tcctor
curve
20
I
25
trovelled
30
35
(cm)
of niisctl sodium fluoritlc, cllrolil~rto~r;r~,hic scpilration.
ctiloridc.
I
I
40
145 M&n t
brutiiitlc
ant1 iodirlc
after
ant! ioclitlc bilH~!S were clifficult to 1OCiltC wit11 CCrtilintv, p:u-ticulnrly tllc ioclidc biLlId, which did not form a lIeiLk. \Vllcn making impctlancc nlc:lSurcmcntS their solutions rcquircd the use of i1 more scnsitivc mctcr. ‘I’llis increnscd the difficulty in rcpcilting rcaclings as the more scnsitivc mctcr picked up rcndings arising from thi? “bnckgrouncl” of the paper itself. It was found tllat tllc p;lper over which tllc solvent llild trilVCl!Cd, itself g;LVC il rcacling of cn. 0.3 ,uA per cm per 25 ml. Conscclucntly, errors associated with them. cliffcrcnt bnntl lcngtlls lid cliffcrcnt “bi~ckground” Attempts to make a correction for the reading due to the “background” did not improve the accuracy, probably becnusc this reading was not uniform along the paper length. The llnlidc ion separations wcrc cnrricd out in tubes instencl of large tanks, since the path length rccluirecl for a scparntion was too great for the tanks available. Conseclucntly thcrc was not overall uniformity in the length travcllccl by the solvent front on cnch paper. This produced a g-cater variation in the band lengths of repeat chromntograms and tllercfore in the meter rcaclings of the solutions obtainccl. The technique employccl in the analysis of the halide. ions cliffcrccl slightly from that
268
J.
A. 13ROOMHEAD,
N. A. GIBSON
cmploycd in the earlier paper on the-alkali metals. In preparing the chromatograms a micromctcr syringe was used to deliver the small volumes; and in extracting the separated bands, a constant volume of water was usecl throughout. Both changes resulted in fcwcr operations, and hence a more rapid analysis. A new solvent mixture was employed in the chromatography and a sample of the type of separation curve obtained is shown in Fig. I. The Xp values of the peaks with this solvent have been determined as follows. _-__-__
-.
IOU ---.-Ii-
CI13rI-
KI
-.---
0
0.20 & 0.03 0.36 f 0.06 o.Gc) * o.oG __- _ ---_~-_
Each Xp clctcrmination is the mean of 5 values. The iocliclc band did not form a peak and instead the centrc of the 1,ancl was taken for the RF measurement. The usual spot test techniques Wei-c applied to identify the zones. ACKNOWI,ISIXEMEN’I
The authors wish to thank the Australian Atomic Energy Commission for a research grant. One of us (J.A.B.) also wishes to thank them for the awarcl of a scholnrship.
/\ new clcvclol~in~ solvent is tlcscrilwtl for the pnpcr C~llollli~tO~~il~‘hic scpariltion of sodium ion zones nrc locittd by the J~LAKI! Zone fluoride, cllloridc, IJromitlc, ant1 iotlitlc. ‘I’llc scpnr;ttd l>ctuctor. :uld the amount of hal itlc ions l)rcscnt dclcrrnincd by lIlC’iLSllrOlllL’Jlt of tllc ilnpcdimcc of their rcnpwtivc nc~i~co~ls cxtrncts.
l.Jnc mdthotlc cnt clkritc pour la wbpnration par chrorll;ltojir;l1,hic .yur papicr tics fluorurc, chlorurc, I)roniurc ct icdurc clc sodium. I.cs zones HfJnt locnlisdcs par lc cldtcctctrr clc aoncs J3LAKIS ct Ia tcncur cn Iialo~dnurcs prdscnts cst tlbtcrmin& par mc?iurc tic I’inipbtl;mcc tic Iciirs cxtraits nquc~ix rcspcctifs.
13cschrcihiing cincr p;rl~icrclirorlintc,&rnpliischcn Mctliodc zur ‘I’rcniiung uncl 13cstimmung Natriumfluoricl, -cllloricl, -1)romid und -jotlicl. I>cr Nnchwcis tier cinzclncn Zoncn gcschicht tlcr Rntlio-lFrcqucnz Mcthodc van 13Lh1<15.Die cinzclncn %oncn wcrdcn hcrausgcschnittcti, Wasscr cstrnhicrt untl tlcr Gclinlt an Salz tlurch hlcssu~~g rlcr lrnpcdnnzcn fcstfpstcllt.
von nnch niit
QUANTITATIVE RECTIFIED PART
II.
CHIMICA
ACTA
CHROMATOGRAPHIC RADIO FREQUENCY
FLUORIDE,
CHLORIDE.
265
ANALYSIS USING METHODS
BROMIDE
.9ND
IODIDE
IWTRODUCTION
In ;in earlier publication 1 the quantitative analysis of mixtures of lithium, sodium and potassium ions by chromnto@aphic and radio-frequency techniques has been described. In this paper the method is cstendccl to the l1alidc ions. The tcchniquc is as follows. Fluoride, chloride, bromide and iodide present as their sodium salts are separated by paper chromatography using a new solvent mixture. The separated zones are cletectcd lq* the radio-frequency mcthocl of I~LAKE~. The bands arc then cut out and the salt present is extracted from the paper with a known volume of water. The impedances of the solutions so obtained arc tl1en measured and compared with those of standard solutions prepared in the same way. The impedance measurements arc made by means of UI,AKE’S conductimetric tub@. ESPERIIIENTAI,
Materials Tl~e analytical grade quality sodium salts were usccl, the fluoriclc and chloride being driecl and weighed directly. The bromide was standardised by the Mohr titration mctl1od3 and the iodide solution by titration with standard potassium ioclatc4. The solutions were made up with distilled water and contained the following amounts of haliclc ion per x00 ml: fluoride, 1.847 6; cllloride, 2.331 g; bromide, 1.516 g; iodide, I.g8g 6. Whatman No. 3 chromatography paper (cut in strips 2.6 x 60 cm) was foung satisfactory. The solvent consisted of a 4:2:x mixture (by volume) of acetone, pyriclinc and water, ancl the organic constituents were used without further purification. The chromatographic separation was carried out in large glass tubes which accommodated two chromatograms per tube. Method Tl1e solutions were placed on a pencil line 2.6 cm from the lower end of the paper by means of an A& micrometer syringe (Burrougl1s Wellcome and Co. London). The range covered was from 0.2-2 mg of halide ion. For each quantity, 20 chromatograms were prepared, 4 being of the mixed 11alides and ‘4 each of the individual halides to * Present address: Chemistry IDcpartment, University of Qucenshnd,
St. Lucia, Brisbane.
Anal. C/rim. Ada, 2d (1962) 265-268
266
J.
A.
RROOMHEAD,
N.
A.
GIBSON
provide the standards. The papers were suspcnclecl from hooks in the chromatography tubes and the ends immersed in the developing solvent to a depth of about I cm. After 24 11the solvent front had moved at least 44 cm up the paper. The slight colouration present in the pyridine of the solvent moved with the solvent front and so provided a permanent recd. of the distance moved. The chromatograms wcrc dried,
‘I’A
131.I’
1
.__. SltrurIicrrI
‘I,,
lirrur
.“_ I~lIIcJritlc l’lIl(Jritlc I~lIIcJrirlc ITI uoritlc lFluoriIlc I~lricwitlc I;IuoriIlc
2;
Clll(Jritk Cl~loritlc Chk’ritlc Chloritlc Clilorirlc Cliloritlc Cliloritlc
H 20
7.5 H‘!
1.73 .!.(I0
4 -’ I 3 .. I I .: I
0.1v
<
.5‘l
O.*=j.!
’ .3x I .7.! l .CJCJ
7’ ‘2
.‘) O.() 10. I Ij.0 IO.0 I ‘)..I ‘L..I .I.”
.-
7. I l.H 13.0 15.x IO.5
.
0.13 0.4.5 O..YIJ I .I 3 I .LO I .fIfj I .CJl 0.S’
’
0.77 I .o., ’ .‘I7 I .72 L *of->
I
4 I
0.7() I .“7
3.5 4.5 S-1 C’ I
Ic’tlith! Iotlitlc IotlitlI! I otliclc I t diclc
I cditlu - __.
‘J.5
0.52 O.S(’ I.13 I .#I”
.I2
lhunitlc I~rI’niiIlc lb’niitlc I~romitlc 1%oniidc I4rc~rnitlc 14rI~Iiiitl~!
I
0.20
3 .! I
._.
tllen conclitioncd for 30 inin in ;ui d.mosl~licrc of rclativc humidity itbOllt c~o”/~ to facilitate finding the bands dth the zone clctcrctor. Alter cutting out, the spots were CStrilctctl with 25 ml of clistillccl w;ltcr. ‘I’lic resulting solutions wcrc illlO\VCd to collie to tclnpcrnture in a COllStiLllt teinpcraturc bath (20 :I: o.:s’) and their impeclanccs then for tlic ioclitlc and bromide measured wit11 the concluctimetric tube. Tllc ITidilIgS solutions wcrc t:ikcn with iL gi~lVnliO~lcter (sensitivity 7.3 mm per ,tcA). For the more conccntratccl chloride ant1 fluoriclc solutions iL less scnsitivc microammetcr could hc cmployccl. The calibration curves were constructed by plotting the mctcr readings against quantity of ion prcscnt for the standards, and the unknowns then rend off from the graphs. The results obtninctl are given in Tnblc I.
QUASTITATIVE
CHIIOJXATOGI~APHIC
267
ANALYSIS
DISCUSSlOS
Consideration
of the results
leads to the following:rangc
of the nnnlyses:
171uoriClc
0.50~-1.00
~'hloridc
o.*jo-2.00
I
I3roniitlc
CJ._50-."."O
fJ
0.50--2.“O
3
Icxlitlc .._. ..-...
_-
.__
2
_ _
It is rcasonoblc that the fluoride and chloriclc analyses should lx the more accurate, since for a given volume they gave solutions of the grcntcr molarity. All other errors bcing equal, the greater the molarity the greater the meter readings, with consccluent tlic fluoride and cliloridc gave sliat-per bnncls on the incrcasetl accuracy I. Furtlicr, paper and so wcrc more rcaclily locntert. The following diagram (Fig. I) shows iL typical separation curve for npprosi~natel~ I-mg il~llOLlrltS ol each lialiclc ion.
CI’(1.3mg)
F ‘4, 60E Y L 40r”
I’ (1.0 mg) -.
I
5
10
15 Distanke
Fig.
x. Typical
‘I’llc bromitlc
ZUIIC &:tcctor
curve
20
I
25
trovelled
30
35
(cm)
of niisctl sodium fluoritlc, cllrolil~rto~r;r~,hic scpilration.
ctiloridc.
I
I
40
145 M&n t
brutiiitlc
ant1 iodirlc
after
ant! ioclitlc bilH~!S were clifficult to 1OCiltC wit11 CCrtilintv, p:u-ticulnrly tllc ioclidc biLlId, which did not form a lIeiLk. \Vllcn making impctlancc nlc:lSurcmcntS their solutions rcquircd the use of i1 more scnsitivc mctcr. ‘I’llis increnscd the difficulty in rcpcilting rcaclings as the more scnsitivc mctcr picked up rcndings arising from thi? “bnckgrouncl” of the paper itself. It was found tllat tllc p;lper over which tllc solvent llild trilVCl!Cd, itself g;LVC il rcacling of cn. 0.3 ,uA per cm per 25 ml. Conscclucntly, errors associated with them. cliffcrcnt bnntl lcngtlls lid cliffcrcnt “bi~ckground” Attempts to make a correction for the reading due to the “background” did not improve the accuracy, probably becnusc this reading was not uniform along the paper length. The llnlidc ion separations wcrc cnrricd out in tubes instencl of large tanks, since the path length rccluirecl for a scparntion was too great for the tanks available. Conseclucntly thcrc was not overall uniformity in the length travcllccl by the solvent front on cnch paper. This produced a g-cater variation in the band lengths of repeat chromntograms and tllercfore in the meter rcaclings of the solutions obtainccl. The technique employccl in the analysis of the halide. ions cliffcrccl slightly from that
268
J.
A. 13ROOMHEAD,
N. A. GIBSON
cmploycd in the earlier paper on the-alkali metals. In preparing the chromatograms a micromctcr syringe was used to deliver the small volumes; and in extracting the separated bands, a constant volume of water was usecl throughout. Both changes resulted in fcwcr operations, and hence a more rapid analysis. A new solvent mixture was employed in the chromatography and a sample of the type of separation curve obtained is shown in Fig. I. The Xp values of the peaks with this solvent have been determined as follows. _-__-__
-.
IOU ---.-Ii-
CI13rI-
KI
-.---
0
0.20 & 0.03 0.36 f 0.06 o.Gc) * o.oG __- _ ---_~-_
Each Xp clctcrmination is the mean of 5 values. The iocliclc band did not form a peak and instead the centrc of the 1,ancl was taken for the RF measurement. The usual spot test techniques Wei-c applied to identify the zones. ACKNOWI,ISIXEMEN’I
The authors wish to thank the Australian Atomic Energy Commission for a research grant. One of us (J.A.B.) also wishes to thank them for the awarcl of a scholnrship.
/\ new clcvclol~in~ solvent is tlcscrilwtl for the pnpcr C~llollli~tO~~il~‘hic scpariltion of sodium ion zones nrc locittd by the J~LAKI! Zone fluoride, cllloridc, IJromitlc, ant1 iotlitlc. ‘I’llc scpnr;ttd l>ctuctor. :uld the amount of hal itlc ions l)rcscnt dclcrrnincd by lIlC’iLSllrOlllL’Jlt of tllc ilnpcdimcc of their rcnpwtivc nc~i~co~ls cxtrncts.
l.Jnc mdthotlc cnt clkritc pour la wbpnration par chrorll;ltojir;l1,hic .yur papicr tics fluorurc, chlorurc, I)roniurc ct icdurc clc sodium. I.cs zones HfJnt locnlisdcs par lc cldtcctctrr clc aoncs J3LAKIS ct Ia tcncur cn Iialo~dnurcs prdscnts cst tlbtcrmin& par mc?iurc tic I’inipbtl;mcc tic Iciirs cxtraits nquc~ix rcspcctifs.
13cschrcihiing cincr p;rl~icrclirorlintc,&rnpliischcn Mctliodc zur ‘I’rcniiung uncl 13cstimmung Natriumfluoricl, -cllloricl, -1)romid und -jotlicl. I>cr Nnchwcis tier cinzclncn Zoncn gcschicht tlcr Rntlio-lFrcqucnz Mcthodc van 13Lh1<15.Die cinzclncn %oncn wcrdcn hcrausgcschnittcti, Wasscr cstrnhicrt untl tlcr Gclinlt an Salz tlurch hlcssu~~g rlcr lrnpcdnnzcn fcstfpstcllt.
von nnch niit