INDUSTRIAL AND ENGINEERING CHEMISTRY
720
Vol. 17, No. 11
tendency of material to slough off during blanching, This could account for the low result obtained in the case of the soft product produced by the 30-minute Carotene blanch. Alcohol-' Insoluble InTable I1 illustrates the great decrease Solids creaae of total solids which occurs during the ?/a. % blanching of carrots in water, the large 2530 .. apparent increases in carotene which are 7.5 2720 recorded on the basis of total solids, and 2.7 2600 the constancy of the carotene values when 2750 8.7 expressed on the basis of alcohol-insoluble solids. 2620 3.6 The relative constancy of the results 5.9 2680 when expressed on the wet basis indi2820 11.4 cates that as far as carrots are con2710 7.1 cerned, the loss of soluble solids is closely compensated by uptake of water. However, the use of the wet basis cannot be advocated until it is tested for the particular product under consideration.
Table II. Carotene Content of Processed Carrots (Calculated on the basis of dry weight snd of alcohol-insoluble iolida)
Treatment Rrw
Blanched 1 min. boiling water Blanched 3 min. boiling water Blanohed 6 min. boiling water Blanched 10 min. boilin water Blanche3 20 min. boiling water Blanched 30 min. boiling water Autoclaved at 10 for 12 minutes
in in in in in in lb.
Total Solids % 12.74
AlcoholInsoluble Solids, Wet Basis
Carotene, Wet Basis
%
Y/O.
Carotene, Dry Weight ?/a. 690
Increase
....
3.46
88
11.24
3.36
91
810
17.4
9.87
3.46
90
910
31.9
9.58
3.39
93
970
40.1
8.71
3.43
90
1030
49.4
7.84
3.35
90
1145
66.0
6.39
3.24
91
1430
107.2
13.52
3.83
104
770
11.6
the several periods of blanching listed, and that the expression of carotene on the basis of alcohol-insoluble solids gives relatively constant results, in contrast with progressively increasing results on the dry weight basis. The principal application for the use of the alcohol-insoluble solids reference base is in the expression of blanching losses, the process in which losses of soluble solids occur. The figures in Table I show that alcohol-insoluble solids in the carrot (Nantes variety) are substantially unaltered by blanching in boiling water, at least for the periods of time used. These figures were obtained by weighing the samples before blanching in boiling water, and grinding and analyzing them after without reweighing. In carving Out this operation, some difficulty was encountered because of the
A
LITERATURE CITED
(1) Bailey, G., and Dutton, H., F ~ u i Products t J.,24, 138, 142, 155 (1945). (2) Kertesa, Z. I., N. Y. State Agr. Expt. Station, Tech. Bull. 233 (1935). (3) Lee, F. A,, and DeFelice, D., Cunner, 94, No. 26, 11-13, 24 (1942). (4) M o w , J. C.,N. Y. State Agricultural Experiment Station, personal communication. (5) Zimmerman, W. I., Tressler, D. K., and Maynard, L. A., Food Rmsarch, 6, 57-68 (1941). APPBOVRD by the director of the New York State Agricultural Experiment Station for publication as Journal Paper NO. 620.
Multiple
Still
For Use in the Willard-Winter Separation of Fluorine H. V. CHURCHILL Aluminum Company of America, N e w Kenrington, Pa.
THE
determination of fluorine in a variety of materials has become increasingly important. The accepted method for isoIating or separating fluorine from organic or inorganic matrices (after ashing if necessary) is the Willard-Winter distillation of fluosilicic acid. I n many laboratories the volume of work is such that many distillations must be made daily. This problem of multiple distillations has been solved a t Aluminum Research Laboratories with the design and construction of a twelve-unit still. Figure 1 shows the parts and details of the apparatus. The apparatus is operated as follows in the analysis of samples which require a double distillation-i.e., a first distillation a t 165" C. and a second a t 135' C. Introduce known amounts of the samples into the Claissen
Basks, 2, wash down the necks and sides of the flasks with water,
and add enough water to make up the volume to 50 to 75 ml. Stopper the flasks and, with the aid of a small funnel connected to the inlet tube, cautiously add 35 ml. of concentrated sulfuric acid to each flask. Rinse out the funnel each time with a little water. After sulfuric acid has been added to all flasks, shake the flasks so that the sulfuric acid and water are thoroughly mixed. Connect the distillation flasks to the steam flask with rubber tubing. Close the steam inlet clamp, 5, on each of the steam generating Basks. Light the burners, 9, under all the flasks, using a high
flame for the steam generating flask and a low flame for the distillation flasks. Steam should be generated before the temperature of 165' C. is attained in the distillation flasks. As soon as 165' C. is reached in any flask, open clamp 5 on the steam inlet tube, close the clamp 4 on the steam release tube, and regulate flame 9 under the steam generating flask so that the pressure is not too great-that is, so the distillate as it come9 from the condenser 3, is cool. When 165' C. is reached in the remainder of the flasks, repeat the above procedure, at the same time lowering the flames under the distillation flasks so 89 t o maintain the desired temperature. The steam inlet tubes in all the flasks should be immersed to about the same depth. Temperatures and rate of distillation are controlled entirely by adjustment of the flame under each flask. As soon as enough distillate is collected from any sample (about 350 ml.), disconnect the rubber tubing from the steam inlet tube, close the steam inlet clamp, 5, turn out the flame under the distillation flask, and readjust the flame under the steam generating flask so as to maintain the correct pressure in the remaining samples. There is usually a sli ht lapse of time between completion of the various samples, so tkat when sufficient distillate has been collected in any receiver, the above procedure should be followed. However, when sufficient distillate has been collected from the last sample served by one steam generator, the rubber tube is disconnected and the steam release clamp opened to prevent formation of a vacuum in the steam generating flask. The flame under the distillation flask must have been turned out immediately
ANALYTICAL EDITION
November, 1945
Figure 1.
121
M u l tiple Fluorine Still blog No. 10-171)
:lamp POliliO" "Wt
(2ooQC.,of ~ u f f i c i mlength l that 130°C. mark i*above r l o w e r ) 0,
n10d
3-insh holrr for dean genwaIi09 Rarkr, amn9.d a, In pholograph
, glarlubing, 6 mm. in ovliide dimetar,
when sufficient distillate was collected. It is also necessary to have the steam release clamp, 4, on the steam generating flask open a t the start of the distillation since, if t h s were closed, together with the three steam inlet clamps, dangerous pressure might develop. Distill about 350 ml. of liquid from each sample and catch in a 400-ml. beaker, 14. Add a few drops of phenolphthalein, and make each distillate alkaline with sodium hydroxide pellets. Then evaporate the distdlates just under the boiling temperature (to avoid meehsnioal loss) to a volume of 10 t o 15 ml., and trabsfer them, with the aid of a little water, to the distillation flash, which have been thoroughly cleaned. Police the beakers with a rubber policeman, and tramfer the rinsings to the distillation flask. The total volume should be about 50 ml. Stopper the flasksand proceed ae before with the followingexceptions: Use perohloric acid instead of sulfuric acid, and maintain the temperature at 135 * 1' C. If the fluorine content is low, the distillates may be caught in two 100-ml. volumetric flasks, tsking a total of 200 ml. If the original sample volume was not more than 75 ml., most of the fluorine will be in the first 100-ml. portion. The reamn for doing this is t o concentrate the fluorine in the fist 100-ml. portion, so as t o obtain a determinable amount by thorium nitrate titration. However, both portions are analyzed, taking suitable aliquots. Often the entire eecond portion may be titrated. However, if the fluorine content is of sufficient concen-
".y"."y,
l"
."
""YY
and neiemw rubbertubing
-_"
I. -.""...I"".- -"" -. .".I-
l " _.I"~._. 1 . .
I
metric flask and then take an aliquot t o obtain a suitable portion for titration. This type of multiple still has been successfully operated for several y e m in Aluminum Company of American laboratories. The only modification of the original assembly which has been found desirable is the substitution of the currently available Claissen flsclks with side arms so constructed that the outlet tube is flush with the top of the side arm. One operator can readily d i d 1 24 samples in one laboratory working day, when two distillations are used on each samde. I n cases where only one distillation is required, 36 analyses for fluorine may be completed eaclb day. ACKNOWLEDGMENT
..
A&.linnmlerlment. . i* marl- nf ront.rihnt,innr. of R.. o .dy.e ._-_I" I_.I__ _.the .__ -.. .-. .. R.. .T. .. . and R. W.Bridges, of the staff of the Analytical Division of Aluminum Research Laboratories, who have cooperated closely with the author, not only in the development and use of the multiple still described in this paper but also in other phases of fluorine analysis
