Characterization of Calcium Hydroxide-Celite Mixtures for Chromatography WALTER A. ROT"
AND ARTHUR
L. LEROSEN, Louisiana State University, Baton Rouge, La.
The chromatographic properties of mixtures of calcium hydroxide and Celite , have been studied. The dependence of the rate of movement of a zone relative to the solvent is similar to that previously found for silicic acid-Celite mixtures. The flow rate of the developer on the composition of the mixture shows a different dependence from that observed in the silicic acid-Celite system.
I
N A previous paper (1) the results of a study of the chromato-
graphic properties of mixtures of silicic acid and Celite (manufactured by Johns-Manville Co.) were reported. In this article the results of a different system, calcium hydroxideCelite, are presented. This system was selected in order to discover whether any or all of the relations found in the first system applied generally to other systems: Calcium hydroxide is different from silicic acid in properties and was therefore considered a suitable substance for the comparison. The terms evaluated were: S , 2'50, V,,and R. Solvent used was commercial benzene; adsorbed solute was lycopene (CaoHd, prepared from tomatoes. Several kinds of calcium hydroxide were tested (Table I ) ; on the basis of these data the reagent grade product of J. T. Baker was selected as most suitable for this work [optimum values ( I ) : V,, 10 to 50 mm. per minute; R, 0.1 to 0.31. In Table I1 the results of the experimental studies are given. The data for 2'50 and V , are shown graphically in Figure 1 and a plot of (1 - R )/ R is shown in Figure 2. There is a striking difference in the dependence of flow rate on volume fraction adsorbent in the two systems, silicic acidCelite and calcium hydroxide-Celite; in the former a linear relation was found between the loglo of either V , or 2'50 and the volume fraction while in this case 7'60 and l / V o give nearly linear relations to volume fraction. This difference is probably related t o the fact that silicic acid shows little tendency to settle or pack under pressure in a column after it has been packed by tapping the column walls, whereas lime can be easily compressed by 1
pressing the top of the column similarly packed. The two cases of silicic acid and calcium hydroxide probably represent the extreme variations of the dependence of flow properties on composition of mixtures. The dependence of R1 for lycopene on the volume per cent adsorbent in the mixture is in agreement with the prediction of the very simple theoretical considerations given in the earlier
4.0
3.0
L. 2.0
L
1 .o
0
0
0.2
0.4
0.6
0.8
1 .o
VOLUME FRACTION OF CALCIUM HYDROXIDE
-
Present address, Standard Oil Company of Indiana, Baton Rouge, La.
Figure 2. Plot of (1 R ) / R against Volume Fraction of Calcium Hydroxide in a Calcium HydroxideCelite Mixture
100
Table I. 80
Chromatographic Characteristics of Five Lime Samples Rl
'
Adsorbent and Source Mississippi Lime Co., St. Genevieve, Mo. Dolomitic hydrated lime, Kelly Island Lime Co. Mississip i Lime and Material Batesville marble lime, Batesville White Lime Co. Calcium hydroxide, J. T. Baker Chemical Co.
60
X
P >
' 2
&.
40
TM
S
Vc
Benzene Lycopene
1.64
84.3
l5,2
0,381
1.69
397.2
3.7
0.178
1.58
154.5
9.5
0 142
1.59
309.1
3.4
0.173
1.52
94.4
11.5
0.230
Table 11. Characteristics of Lime (Baker)-Celite Mixtures
20
Lime Fraction in Mixture Weight, Volume, 0
0
0.2 0.4 0.6 0.8 VOLUME FRACTION OF CALCIUM HYDROXIDE
1 .o
Figure 1. Plot of Tho, :>, and 1/Vc x lo3, 0 , against Volume Fraction of Calcium Hydroxide in a Calcium HydroxideCelite hlixture 1092
Mg.
MI.
1.00 0.90 0.80 0.50 0.20 0.00
1.00 0.83 0.69. 0.36 0.12 0.00
S 1.52 1.53 1.53 1.53 1.38 1.35
Ri
Tho
Vc
l/Vc
Lycopene Benzene
94.4 86.2 75.5 33.7 12.8 3.6
11.5 13.0 14.9 31.9 98.0 355.0
0,087
0.230 0.261 0.327 0,490 0.725 1.000
0,077 0 067 0,031 0 010 0,003
V O L U M E 2 0 , NO. 11, N O V E M B E R 1 9 4 8
1093
communication-there is a linear relation between the quantity (1 - R )/ R and volume fraction of adsorbent. The quantity S was practically constant until a high fraction of Celite was present in the mixture; it therefore showed no consistent variation with composition and v-as not plotted.
LITERATURE CITED (1) LeRosen. 4 . L., J . Am. Chem. Soc., 67,1683 (1946).
RECEIVED March 3, 1948. Part of a thesis submitted b y Walter A. Roth t o t h e Graduate sohoo1 of Louisiana State University in partial fulfillment of the requirements for the master's degree.
Rate of Movement of a Chromatographic Zone as a Function of Temperature ARTHUR L. LEKOSEN AND CHARLES -4.RIVET, JR., Louisiana State C'nicersity, Baton Rouge, La. In order to use the term R (ratio of movement of zone on column to movement of solvent in column) for study of the behavior of substances in the chromatographic column, i t is necessary to know how this quantity depends on the variables in the system. Some data are available for all important variables except temperature. For this variable only a qualitative statement is on record that changes i n zone sequence will take place with changing temperature. In the present work three systems have been studied
T
HE factors affecting the rate of movement of a single chromatographic zone in a system consisting of only one adsorbent and one solvent have been investigated quantitatively by several workers. LeRosen ( 4 ) has developed an empirical equation expressing R for the leading edge of a zone as a function of initial concentration and initial volume. For the trailing edge of a zone R was found to be independent of both initial concentration and volume. Weil-Malherbe (6) has developed similar equations for Vt (the volume of filtrate collected before the solute first appears in the filtrate) as a function of quantity
A
z 0
0.30
k t 0
and the variation of R for the leading edge of the zone is recorded graphically as a function of temperature. All the R-temperature curves show a flat region a t about 20" to 35" C. and two out of the three show rapidly increasing values of R with temperature outside this region. No special control of temperature is necessary for these systems in the region 20' to 35" C., but since other systems maldiffer from these, i t is desirable to report the temperature a t which a given R determination is made.
of adsorbent, initial volume, and quantity of solute. Austin and Shipton (1) have shown that R is independent of the rate of filtration. Strain ( 5 ) has indicated that the adsorption sequence of certain organic compounds is dependent to some extent on temperature. This adsorption sequence is directly proportional to the rates of movement of the individual compounds. This study was undertaken primarily to determine the part temperature plays as an uncertainty factor in ordinary chromatographic work, particularly in standardization of adsorbents and studies of rates of movement of chromatographic zones. The system, o-nitroaniline-silicic acid-benzene, was chosen for study. The results are given in Figure 1. Fortunately for this system, temperature had relatively little effect on R over the range 20" to 35" C. It could be concluded therefore that any measurement of R a t ordinary room temperature would be fairly reliable (all other variables being held constant) and no special precautions need be taken for controlling the temperature. The question as to whether or not the behaviar shown in Figure 1 was characteristic of all systems led to the selection of two other systems having R values ranging from 0.1 to 0.3 a t room temperature. Data for the systems o-nitroaniline-silicic acidchloroform and lycopene-calcium hydroxide-benzene are given in Figure 1. All three systems show the least change in R with temperature over the range 20 to 35 C. and consequently any room temperature measurement of R for these systems would be fairly reliable. The temperature, however, should be stated when R values are given for other systems. O
%".20t3 6
DISCUSSION
" I
Figure 1. Relation between Ri (Leading Edge of Zone) and Temperature
I t has been shown (3) that R is identical with the fraction of the total time spent in solution by a solute molecule as it moves down the column. If T , is defined as the average time a solute particle spends in solution between successive adsorptions and To as the average time the particle spends on the adsorbent, then R is given by T 8 / (T , T,). Although it is not now possible to describe exactly the behavior of T , and Ta as functions of temperature, the following can be said with reasonable certainty.
o-Nitroaniline-ailicic acid-benzene. o-Nitroanilingsilicic %d-chloroform. 8. Lycopene-calcium hydroxide-benzene. Each point represents average of 5 to 10 determinations of RI on a single column
For a region of relatively small change in R with temperature, one of the following must be true for the fraction, T a / (T. Tal. Case 1. The relative ratesof change of the numerator and the
IO'
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