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Contribution to the theory of the retention index system
JOUIWAJ,
01: CHHOMA-KJGRAI’HY
29
4465
CHROM.
CONTRIl3UTION
TO THE
I, RETENTION INDICES CHROMATOGRAPHY
THEORY USING
OF THE
RETENTION
INDEX
PROGIIAMMED-TEMP~IlrlTUliE
SYSTEM GAS
After esainining the relationship between retention indcs and column temperature under isothermal conclitions, we have shown in a recent publication that -the temperature-dependence of the retention index may generally be determined by an Antoine-type equation : I
stationary substance
phase
(1‘) _~+--L_
‘1’ + c
After further investigation, \ve have established exactly calculated from proh’ral7iiilecl-temperature following equation : 2,
(A
+
-ii.. f:
c. ly--T”
A great advantage not included in it.
&W
-2.~-~3dog ==A+-
of this equation
-7’
that tile retention indices can be gas cliroiiiatograpl~y data with the
;;:;;;-I r -
T,,
--]
is that tl;e data from normal
l~ydrocarbons
m-c
INTI
It is generally known that working without pure standard sul~stances, tile retention index system worked out by IiovLW is tile most important one among the qualitative evaluation methods of gas cliromatograpliy. The retention indices give a suitable foundation--beyond the application n-tentionecl -for other investigatior@J, ancl as a result of this recognition increasing interest has been manifested in recent years in some problems of the retention indes system. Among these questions, the application of the retention index system is most prominent in l~rogrammecl-tenlperature gas clironiatograpliy (PI‘GC). Although in this field the appmpriate equations of VAN DEN Door, AND KRA-w’, GUIOCHON”, 1~A13GOOD AND HARRIS” and GIDDINGS’, */. Cllro~?ratog., qcq 1970)
ag-32
L. DRDEY, J. TAKkS,
30
6.. SZALANCZY
among others, are available the differences in index experienced in some cases have stimulated the researchers working in this field to undertake further investigations. Also GOLOVNYA AND URALETZ~, in addition to suggesting a new equation for using isothermal retention indices under PTGC conditions, are dealing with index-influencing factors and also are comparing different methods of index conversion. In examining the relationship between retention index and column temperature under isothermal conditions, we recently demonstrated0 that the temperature dependence of the retention index may generally be determined by an Antoine-type equation : I st. ph. substance (“)
= A +
T _“t C
where I = the symbol for the retention indes T = column temperature in “K = constants of the Antoine-type ecln. (I). A, BandC The three constants of the equation depencl only on the quality of the substance and of the stationary phase and can easily be determined from esperirnental results”. Considering this information, we supposecl that relying on eqn. (I), the index values in PTGC may be exactly described. In this paper we report on the results reached so far, based on data in the literature‘+* and on our measurements. THEORY In our investigations we have been concerned only with cases in which the continuous temperature programming started simultaneously with the introduction of the sample and terminated only after the elution of the component examined; it may be described by a constant heating rate, /? (“C/min). In the case examined, the following relationship is applica’ble, using the average value of integration : 1r
st. ph.
I substance
(P-=C)
=
(A
+
+)
---yr
_
dl‘
(2)
7., ---
where Tr = retention temperature in “l(. T0 = initial temperature in “K. Solution of the integral calculus in the numerator yields :
Tr (A+ Arr
T
;
c
) dT
=
i- B lln (IT, -+- C) -
[AT AT,
I3 aIn (I’
+ -
(T,
-
J. Ckromatog.,46 (x970) 29-32
+
A (T,
side of eqn. (2)
C)] ‘V L= ‘I’0
B~ln (I‘, + C) = n (I’,. _
Cln(G + C) - In (1’, + C)] lB = A
on the right-hand
-
To)
+
r,)
+
13*lx1 ( F .
1 ;
) =
0
(3)
CONTRIBUTION
Thus
TO THE
THEORY
RETENTION
INDES
SYSTEM.
I.
31
for ecln. (2) WC may write:
st. ph. I su,,stT*Icc (PTGC) . c 2 -3
A +
’
f! *log
A (TT -. k’“) + 2.3 *u *log (-g-~-g) .,. = I r - T,, 7-r +
(T-C
c
-!---
---‘1’
r
Eqn.
OF THE
=
)
(4)
- T,,
(4) is suitable for the esact
calculation
of retention
indices in YTGC.
l;,SI’ERIM13X’I’AT.
Our measurements were made using gas cl~romatograplls (Carlo Erba Model C, D, GV and GI-452) with flame ionisation detectors in all cases. Carrier gas was N,, while ausiliary gases were H, and 0,. Stationary phases were squalane ; the silicone aclipate ; di-ethyloils, SE-30, DC-200, DC-550, DC-702 ; Apiezon I, ; di-ethyleneglycol eneglycol succinate; polyethylene glycol 1500 (PEG-1500) ; and polyethylene glycol 20 M. As an esample we present the calculation of benzene using PEG-1500 as stationary phase. The retention incles of benzene on PEG-1500 under isothermal conclitions is dependent on column temperature according to the following equation:
When the initial temperature, 7’, was S4OC, the retention temperature, TT was s)g”C. [p = 4.~“C/min]. The corresponding data are substituted into eqn. (4) and the following calculations are made. I
Y’EG-I~OO
Benzene
=
I
(WGC)
71s $-
-
2.3
* (-
2.3 * (-I 71s $_ _~__
1718
I
2.3 q+ ----_
718 -
I 71s We compared data in the literature shown in Table I.
x 032
I
240) *lcjg (~+$$-) -372 -- 357
032 240) slog ( r :zz -__L IS
I 032 240) alog 1.0113 15
2.3 - I 032 240 *o.dbqc) -=5
- zzz
)
&.
=.z
z.zzz
776 = 942
with that calculated
(6) by erln. (6). The results are ,J.
Chl’CJlll~tO&‘.,
40
(1970)
29-32
32
L. ERDEY,
.TABLE
I?. SZALnNCZY
I
COMPARISON Index
J. TAICACS,
OF Rl%TENTION INUES
DATA
units
Literature data
Calculated by eyn. (6)
944” 943b 943=
942 942 942 a VAN DEN b GIIXXNGS c GO~OVNYA
Divergence from calculated value
=: +I DOOL AND KRATZ (ref.4). (ref.7). AND URALETZ (ref.5).
SYMUoLS
I T
= =
To
= =
TV
A, BandC P st.
ph.
= = =
retention index column temperature initial temperature retention temperature constants of Antoine-type heating rate stationary phase
equation
REFERENCES
I E. KOVATS, Helv.
Chz’m. Acta, 41 (195s) 1915. L.ROHRSCHNEIDER,Z. Anal. Cl&em., 236 (1968) 149 . J.JONAS, J. JANAK AND M. ICRATOCHVIL, J.Gas Clwomatog., 4 (rgGG) 332. H.VAN DEN DOOL AND P.DEc. KRATZ, J. Chromatog., II (1gG3) .+G3. G. GWIOCHON, Anal. Gkem., 36 (1964) 6G1. H. W. HABGOOD AND W. E:.HARRIS, Anal. Chcm., 36 (IgG4) 6G3. J.C. GIDDINGS, in N. BRENNER, J. E. CALLEN AND M. D. WEISS (Editors), Gns C/I~VW~~~Jgraphy, Acaclemic Press, New York, rgGz, p. 57. S R,V.GOLOVNYA AND V.P.URALET%, J. Clwomatog., 3G (rg6S) 270. g J. TAKACS, M, ROCKENRAUER AND I. OLACSI, J. Chvomatog., 42 (1969) 19. 2 3 4 5 6 7
J.
Chvomatog..
46 (1970)
29-32
01: CHHOMA-KJGRAI’HY
29
4465
CHROM.
CONTRIl3UTION
TO THE
I, RETENTION INDICES CHROMATOGRAPHY
THEORY USING
OF THE
RETENTION
INDEX
PROGIIAMMED-TEMP~IlrlTUliE
SYSTEM GAS
After esainining the relationship between retention indcs and column temperature under isothermal conclitions, we have shown in a recent publication that -the temperature-dependence of the retention index may generally be determined by an Antoine-type equation : I
stationary substance
phase
(1‘) _~+--L_
‘1’ + c
After further investigation, \ve have established exactly calculated from proh’ral7iiilecl-temperature following equation : 2,
(A
+
-ii.. f:
c. ly--T”
A great advantage not included in it.
&W
-2.~-~3dog ==A+-
of this equation
-7’
that tile retention indices can be gas cliroiiiatograpl~y data with the
;;:;;;-I r -
T,,
--]
is that tl;e data from normal
l~ydrocarbons
m-c
INTI
It is generally known that working without pure standard sul~stances, tile retention index system worked out by IiovLW is tile most important one among the qualitative evaluation methods of gas cliromatograpliy. The retention indices give a suitable foundation--beyond the application n-tentionecl -for other investigatior@J, ancl as a result of this recognition increasing interest has been manifested in recent years in some problems of the retention indes system. Among these questions, the application of the retention index system is most prominent in l~rogrammecl-tenlperature gas clironiatograpliy (PI‘GC). Although in this field the appmpriate equations of VAN DEN Door, AND KRA-w’, GUIOCHON”, 1~A13GOOD AND HARRIS” and GIDDINGS’, */. Cllro~?ratog., qcq 1970)
ag-32
L. DRDEY, J. TAKkS,
30
6.. SZALANCZY
among others, are available the differences in index experienced in some cases have stimulated the researchers working in this field to undertake further investigations. Also GOLOVNYA AND URALETZ~, in addition to suggesting a new equation for using isothermal retention indices under PTGC conditions, are dealing with index-influencing factors and also are comparing different methods of index conversion. In examining the relationship between retention index and column temperature under isothermal conditions, we recently demonstrated0 that the temperature dependence of the retention index may generally be determined by an Antoine-type equation : I st. ph. substance (“)
= A +
T _“t C
where I = the symbol for the retention indes T = column temperature in “K = constants of the Antoine-type ecln. (I). A, BandC The three constants of the equation depencl only on the quality of the substance and of the stationary phase and can easily be determined from esperirnental results”. Considering this information, we supposecl that relying on eqn. (I), the index values in PTGC may be exactly described. In this paper we report on the results reached so far, based on data in the literature‘+* and on our measurements. THEORY In our investigations we have been concerned only with cases in which the continuous temperature programming started simultaneously with the introduction of the sample and terminated only after the elution of the component examined; it may be described by a constant heating rate, /? (“C/min). In the case examined, the following relationship is applica’ble, using the average value of integration : 1r
st. ph.
I substance
(P-=C)
=
(A
+
+)
---yr
_
dl‘
(2)
7., ---
where Tr = retention temperature in “l(. T0 = initial temperature in “K. Solution of the integral calculus in the numerator yields :
Tr (A+ Arr
T
;
c
) dT
=
i- B lln (IT, -+- C) -
[AT AT,
I3 aIn (I’
+ -
(T,
-
J. Ckromatog.,46 (x970) 29-32
+
A (T,
side of eqn. (2)
C)] ‘V L= ‘I’0
B~ln (I‘, + C) = n (I’,. _
Cln(G + C) - In (1’, + C)] lB = A
on the right-hand
-
To)
+
r,)
+
13*lx1 ( F .
1 ;
) =
0
(3)
CONTRIBUTION
Thus
TO THE
THEORY
RETENTION
INDES
SYSTEM.
I.
31
for ecln. (2) WC may write:
st. ph. I su,,stT*Icc (PTGC) . c 2 -3
A +
’
f! *log
A (TT -. k’“) + 2.3 *u *log (-g-~-g) .,. = I r - T,, 7-r +
(T-C
c
-!---
---‘1’
r
Eqn.
OF THE
=
)
(4)
- T,,
(4) is suitable for the esact
calculation
of retention
indices in YTGC.
l;,SI’ERIM13X’I’AT.
Our measurements were made using gas cl~romatograplls (Carlo Erba Model C, D, GV and GI-452) with flame ionisation detectors in all cases. Carrier gas was N,, while ausiliary gases were H, and 0,. Stationary phases were squalane ; the silicone aclipate ; di-ethyloils, SE-30, DC-200, DC-550, DC-702 ; Apiezon I, ; di-ethyleneglycol eneglycol succinate; polyethylene glycol 1500 (PEG-1500) ; and polyethylene glycol 20 M. As an esample we present the calculation of benzene using PEG-1500 as stationary phase. The retention incles of benzene on PEG-1500 under isothermal conclitions is dependent on column temperature according to the following equation:
When the initial temperature, 7’, was S4OC, the retention temperature, TT was s)g”C. [p = 4.~“C/min]. The corresponding data are substituted into eqn. (4) and the following calculations are made. I
Y’EG-I~OO
Benzene
=
I
(WGC)
71s $-
-
2.3
* (-
2.3 * (-I 71s $_ _~__
1718
I
2.3 q+ ----_
718 -
I 71s We compared data in the literature shown in Table I.
x 032
I
240) *lcjg (~+$$-) -372 -- 357
032 240) slog ( r :zz -__L IS
I 032 240) alog 1.0113 15
2.3 - I 032 240 *o.dbqc) -=5
- zzz
)
&.
=.z
z.zzz
776 = 942
with that calculated
(6) by erln. (6). The results are ,J.
Chl’CJlll~tO&‘.,
40
(1970)
29-32
32
L. ERDEY,
.TABLE
I?. SZALnNCZY
I
COMPARISON Index
J. TAICACS,
OF Rl%TENTION INUES
DATA
units
Literature data
Calculated by eyn. (6)
944” 943b 943=
942 942 942 a VAN DEN b GIIXXNGS c GO~OVNYA
Divergence from calculated value
=: +I DOOL AND KRATZ (ref.4). (ref.7). AND URALETZ (ref.5).
SYMUoLS
I T
= =
To
= =
TV
A, BandC P st.
ph.
= = =
retention index column temperature initial temperature retention temperature constants of Antoine-type heating rate stationary phase
equation
REFERENCES
I E. KOVATS, Helv.
Chz’m. Acta, 41 (195s) 1915. L.ROHRSCHNEIDER,Z. Anal. Cl&em., 236 (1968) 149 . J.JONAS, J. JANAK AND M. ICRATOCHVIL, J.Gas Clwomatog., 4 (rgGG) 332. H.VAN DEN DOOL AND P.DEc. KRATZ, J. Chromatog., II (1gG3) .+G3. G. GWIOCHON, Anal. Gkem., 36 (1964) 6G1. H. W. HABGOOD AND W. E:.HARRIS, Anal. Chcm., 36 (IgG4) 6G3. J.C. GIDDINGS, in N. BRENNER, J. E. CALLEN AND M. D. WEISS (Editors), Gns C/I~VW~~~Jgraphy, Acaclemic Press, New York, rgGz, p. 57. S R,V.GOLOVNYA AND V.P.URALET%, J. Clwomatog., 3G (rg6S) 270. g J. TAKACS, M, ROCKENRAUER AND I. OLACSI, J. Chvomatog., 42 (1969) 19. 2 3 4 5 6 7
J.
Chvomatog..
46 (1970)
29-32