V O L U M E 28, NO. 7, J U L Y 1 9 5 6
1091
Figure 21. Dumb-waiter and contaminated apparatus hood Figure 22.
Decontamination room
foot of usable floor space was $80. The total cost per square foot of usable floor space for the same area was 5210. ACKNOWLEDGMENT
The successful completion of a project of this magnitude would have been impossible without the full cooperation of many of the Chemical Processing Plant personnel. The authors especially acknowledge aid given by the following: Engineering Design Section, Instruments Section, Operations Section, Maintenance Section, Shift Control Lahoboratory, and the Central Facilities Shops.
Final credit is due the Blaw-Knox Co., Pittsburgh, Pa., for building design and construction superviBion, the J. F. Pritchard Construction Co., Kansas City, Mo., for building construction, and the Engineering Branch, Idaho Operations Office, Atomic Energy Commission, for over-all supervision and li$son. R E C E W ~for D review September 6. 1955. Aocepted February 13. 1956. Presented before the Nuolear Engineering and Science Congress, Cleveland, Ohio, December 1 2 t o lo, 1955. Work performed under contrmt No. AT(10-1)-205 with the Idaho Operatioar Office, U. S. Atomic Energy COmmi%SiOn.
Use of Paper Chromatography for Differential Analysis of Phosphate EDITHA KARL-KROUPA Research Department, Monranto Chemical Co., Dayton 7, O h i o
Several procedures for differential analysis of mixtures of condensed phosphates were developed on the basis of Ebel’s technique of ascending paper ohromatography. A new quantitative method has been developed for mixtures containing ortho-, pym-, and triphosphates (tripolyphosphates), as well as rings (trimeta- plus tetrametaphosphates), and long-chain phosphates. In addition to a one-dimensional chromatogram, this technique involves a two-dimensional ohromatogram in which the second solvent advances in the opposite direction of the first solvent (180’ apart). This proocdure and the Ebel technique, in which the solvents are run at right angles to each other, have been put on a routine basis suitable for use in oontrol laboratories. A special colorimetric prooedure employing an extraction step makes possible the rapid quantitative evaluation o f the chromatographic fractions. .4nalyses are described for oommercial sodium triphosphate, built detergents without the use of any previous treatment of the sample, and surface waters. IIydrolysis during the ohromatographio run was investigated and small correction factors are recommended for the most precise results.
T4,
HOUGH excellent contributions have recently been made to
the general analytical problem of phosphate mixtures (8, 6, 9,11, 13, 17, 18,80, 81),there is still a need for a reasonnbly quick procedure which uses easily available equipment and reagents and is sufficiently accurate for a quantitative assay of the commercial phosphates and phosphate-containing products. Paper Chromatography for the differentid andyais of inorganic phosphorus compounds has been primarily developed by two groups of investigators-one in Canada and one in France. The Canadian investigators have worked aut a quantitative procedure (4, 81) based on descending chromatography using considerably longer separation times than are employed here. The French group has emphasized qualitative measurements by ascending solvent fronts (5). They have also developed a regular two-dimensional technique which separates ring and chain phosphates into two distinct groups (6, 6). The semiquantitative techniques described by Ebel have been developed into a reasonably precise quantitative procedure by the use of sample hands (containing larger sample weights) in.stead of spots and very short run8 to minimize errors due to hydrolysis. The precision of this procedure appears to he as good as that obtained with descending chromatography ( 4 , 81); use of a hydrolysis correction improves the accuracy. The
ANALYTICAL CHEMISTRY
1092
the chromatographic paper. This means that volumes up to 0.075 ml. can be applied on one spot, without exceeding the convenient diameter of the sample spot of about 3/8 inch. PRETREATMENT O F CHROUATOQRAPHIC SOLVEKTS. Because better patterns are obtained with solvent that has been used in a couple of runs, a pretreatment of the solvent is carried out by simulating two runs, using corresponding areas of the chromatographic paper and following the procedure described later. The solvent can be used by replenishing the volume after every three EXPERIMEIVTAL or four runs Kith fresh untreated solvent. The filter paper is cut into sheets 9 inches wide PROCEDURE. Equipment and Materials. Rectangular batter\jar., ahout . . by 6 or 9 inches high, depending on the analysis for which it is 12 by 8 by 0 inches. being prepared. Contamination, even with traces of phosphates, Cylindrical jars (1-gallon pickle jars), about 6 inches in diammust be avoided. The starting lines and spots for sample :inti eter with 3l/?-inch ouenina: about 11 inches hieh and fitted with reference material are marked, as indicated later, with an ordiPrtri dish covers. nary graphite pencil, and the sheets are stored lying flat ill a dristMicropipets, 50 pl. with subdivisions for I0 pl. free cabinet. Screw control for micropipets. Immediately before the c.hromat,ographic analysis is s m t e d , Plat'inum wire, about 0.02 inch in diameter. the prepared sheet is folded into a cylinder and clipped together Chromatographic spray bottle. with platinum wire about 11/2inches long, in such a \vay that the Ultraviolet lamp, long wave, xhich can be arranged to cover edges do not touch. The sample solution and the reference solu:in area 9 by 9 inches. tion are applied on the proper starting spots nlth the micropipet, \Vater bath, consisting of a hot plate with several 600-ml. and the spots are allowed to dry for a few minutes. glass beakers and glass beads. The cylinder is then inserted into a rectangular battery jar Safety aspirator, such as a Propipctte from 1T-ill Carp. Ivhich contains a beaker with some of t,he chromatographic solvent Electrophotometer, wit,h a light path of 10 to 20 mm., and a red to be used in the subsequent separation, and the jar is covered filter with it,s maximum a t 620 to 650 mp, &th a well-fitted glass plate. If more than one sheet is stored Filter Paper, Schleicher & Schuell, 589, orange ribbon, special in the jar a t the same time, the sample spots on one sheet must paper for paper chromatography. not touch the other sheet. The cylindrically rolled sheet is exReagents. EBEL'S CHROX~TOGRAPHIC SoLvEs-rs ( 5 , 6). Acid posed to the vapor for 45 minuter, without getting drops or spots solvent is made by mixing 750 ml. of isopropyl alcohol. a solution of t'he solvent on the paper. of 50 grams of trichloroacetic acid in 250 ml. of water, and 2.5 ml. After this pretreatment the paper cylinder is transferred withof concentrated ammonia. Basic solvent is made by mixing 400 out delay, starting line or staiting spot down, to a cylindrical nil. of isopropyl alcohol, 200 nil. of isobutyl alcohol, 390 nil. of jar (I-gallon) which contains 150 ml. of the chromatographic. iyater, and 10 ml. of concentrated ammonia. solvent. This jar is covered immediately vith the fitted Pet1.i CHROXITOGRAPHIC Y . This is made according to Hanes dish. The sheet is inserted carefully to avoid splashing or waveng 5 ml. of 60% perchloric acid, 1 ml. and Isherwood (10) b j like movement of the solvent which rould cause an uneven startof concentrated hydrochloric acid, and 1 gram of ammonium ing level for the ascending run. The upright edges must not heptaniolybdate tetrahydrate and diluting to 100 nil. with distouch each other. The 150-ml. volume of chromatographic soltilled miter. inch high: the sample and vent in the jar forms a layer about REBGESTSFOR EXTRACTIOS ASD HYDROLYSIS. .immoiiia and reference spots, which in all cases are applied 1 inch h o v e the sulfuric acid, both about, 8iV. bottom edge of the sheet, are thus not immersed in the solvent. REAGESTSFOR COLORIMETRIC DETERMISATIOS OF PHOSPHORL-b This prevents mashing out of the sample and contamination of ~ ' E Z T O X I D E . The following are required: a 10% aqueous soluthe chromatographic solvent. The jar must not be moved, and tion of ammonium heptamolybdate tetrahydrate; a mixture of must be kept covered during the run. equal volumes of isobutyl alcohol and benzene; 2% sulfuric acid \Then the run is complete, the sheet is easily removed by grasp(by volume) in aldehyde-free absolute methanol; a solution of ing the tn-0 upper corners and folding them slightly over each 25% stannous chloride in concentrated hydrochloric acid, preother so that the cylinder is deformed to a cone. The excess pared according to Martin and Doty ( I d ) : 1 S sulfuric acid; and chromatographic solvent is rrmoved from the paper by touching reducing agent. This latter soliition is not stable for more than the bottom of the upright cylinder to a paper towel or absorbent 1 day and is prepared as needed by adding 0.5 ml. of stannous tissue several times. chloride solution to 100 ml. of 1 S sulfuric acid. The sheet cylinder is left stantling on the towel for about 10 Reference Standards. Reagent grade chemicals Jvei'e used minutes, then transferred to a drying oven a t 50" C. for 10 more to prepare the standards listed beloiv, except for sodium triminutes. The platinum clip is removed, the sheet is bent flat and phosphate hexahydrate, a lahoratory preparation purified by sprayed evenly over the whole area with the chromatographic fractional recrystallizations ( 1 7 ) ; sodium trimetaphosphate, a spray solution. Drops of liquid must not form on the paper. lahoratorj- preparation purified by t x o recrystallizations and The sprayed sheet is dried for 10 minutes in the oven a t 50" C., dried at 110' C. ( 1 4 ) ; and sodium tetrametaphosphate tetrathen placed under the ultraviolet lamp and irradiated until the hydixte, a laboratory preparation (8 or 1 ) followed by rwrystalblue zones appear. If the sheet has been covered evenly by the lization. irradiation, this operation is complete after the reference spots ~'YROPHOSPHATE S~.asna~u, (d). This contained about 1 y of are clearly visible. phosphorus per pl., and \vas made by dissolving about 0.7 gram The zones should be marked with pencil soon after they have of tetrasodium pyrophosphate dccahydrate in 100 nil. of water. become visible in such a way as to exclude reference spots defiORTHO-, PYRO-, TRI-, TRI.\IETAl'HOSP€IATE S T A Z D A R D , ( B ) . nitell- but to include the rntire paper area which carries the This standard contained :tljoiit 0.4 y of each phosphoriis species respective fraction. hloderate1)- curved lines are as satisfactory per pl.-i.e.j about 1.6 y of total phosphorus per p l . It [vas prcas straight lines. If two fractions of the pattern are located close pared by dissolving 0.4 gram of monopotassium orthophosphate, together, the pencil mark must follow the line of the weakest color 0.7 gram of tetrasodium pyrophosphate decahydrak, 0.,5 gram of intensity. JVhen band chromatograms obtained in an acidic onesodium t,riphosphate hexahydrate, and 0.35 gram of sodium tridirectional run are analyzed, the separating line between the metaphosphate [(NaP03)BJin 250 ml. of xater. and triphosphate fractions is drawn as close as possible to ORTHO-, PYRO-, TRI-, TRIMETA-,T E T R A ~ ~ E T A P H O h P H - I T E : pyrothe pyro band, because the correction value (given later) was STASDARD, (C). This standard contained about 0.4 y of each determined empirically under these conditions. The ortho fracphosphorus species per pl,! or about 2.0 y of total phosphorus per tion is marked symmetrically to the colored zone and any paper pl. It was prepared like standard B , except that 0.4 gram of area left over between the pyro and ortho bands can be dissodium tetrametaphosphatr tetrahydrate [(SaP03)44H?O] was carded (only minute amounts of phosphorus which fall xithin the added. error of the colorimetric det,erinination are located on this area General Technique. S . u r P m U-EIGHT. The capacity of the after a 21/r-hour run). In a two-directional band chromatogram chromatographic paper for short runs is 10 y of total phosphorus for ring phosphates the line Tvhich separates rings from chains is per spot. The most convenient volume for one spot iL*about 5 drawn half-way betxeen the ring band and the chain bands. If a MI., which yields spots on the paper about 3/8 inch in diameter. fraction is too weak to show up, an area is marked in the position The sample solution should therefore contain 2 y of total phosindicated by the reference spots. phorus or a little less per p l . More dilute sample solutions can be For the short-cut elution (described later) it is essential to used by repeatedly applying 5-pl. droplets on the same spot, with square inch or better. An area match the paper areas within complete drying after each addition. I n qualitative analysis, the of about 3 square inches of the phosphate-free blank area is also point, of the micropipet must tourh the paper exactly on the marked on every sheet for quantitative analysis. This area is center mark of the sample spot each time. Up to 15 subsequent treated like the other frartion.? to obtain a reagent blank. applications may be rarrietl out \vithout destroying the trxture of
elapsed time for a quantitative assay is considerably shorter than that considered necessary by previous investigators. These analyses are applicable to mass-production techniques because common glass jars are employed in place of the elaborate and well-sealed chromatographic chambers usually needed foi clear-ciit separation in deqcending chromatography (4,21 ).
-
I,
Y
V O L U M E 2 8 , NO. 7, J U L Y 1 9 5 6
1w3 flask. The contents are mixed and the volume is made up to the mark with sulfuric acid-methanol. The blue solution is carefully
T h i y must be small enough to permit efficie'nt rinsing with relatively 8mdl volumes, because the colored solution has a volume of only 25 ml. The absorbance of the reagent blank is deducted from the other readings to give a net absorbance for every fraction. The total abrrorbmce for the analysis is determined by adding the net ab-
.by"t h i total absorbance for the respective andysis. SPECIFIC APPLICATIONS
Qualitative Identification of Ring and Short-Chain Phosphates. In the qualitative tw-directional separation described byEbel(6,6) the R, values were found to vary considerably with the experimental conditions, especially in the basic solvent. As a result, positive qualitative identificat.ion of unknowns is not always possible if the conditions are not oontrolled precisely. This difficulty has been solved by adding pyrophosphate as an internal standard, and using a mixture of readily-axailable known phosphates as comparison standards in the acid run. Pyrophosphate a8 the internal standard reproducibly established the borderline between the ring-plus-orthophosphate and the chain-phosphate areas. The comparison standmds are applied after the hssio run to the area which is free of unknowns but has been penetrated by the basic solvent. The R , values of orthw, pyro-, and triphosphate are obtained from the comparison standards on the same sheet and are used to prepase a calibration curve for identification of higher chain phosphates. This technique has been used to identify ion exchange fractions up to heptaphosphate from a glassy sodium phosphate and has proved suecessful in assaying condensed phsaphates in a wide variety of mixtures with different substances.
rxgure
I.
Iwo-(1Ir~cc.onalcnromarograrn Ior
yUaL'La-
tive identifieation of ring and chain phosphates
SHORT-CUT PROCEDURE WITHOUT ELUTION STEP. The paper areas far the single fractions m e matched t o within square inch, using some paper from the paper blank area if necessary. Wide zone8 can be handled as two or three fractions. Each fraction, as well as a %square inch reagent blank, is cut into pieces (about '/$ inch long and I/g inch wide) and transferred to 25-ml. flasks. After 1 ml. of 8N ammonia and i ml. of distilled water have been added, the flasks are swirled and allowed to stand for 5 to 10 minutes. Then 3 ml. of 8N sulfuric acid is added-1 ml. to be equivalent to the ammonia already added and 2 mi. to make the solution strongly acidic for hydrolysis. All the flasks containing the fractions of one analysis must be handled as a group to ensire similar treatment. Hmnoiysrs AND C o ~ o nDEVELOPMENT.The 25-ml. flasks, containine all the Dhomhate in 8. strone acidio solution. are placed i n d water b i t h i t the boil for 20 minutes. Though the orthophosphate fraction does not require any hydrolysis, it is included in the procedure to ensure uniform treatment. This 20-minute period is sufficient to hvdrolvze all condensed Dhosohates mesent in this solution Afte; the flasks have cooled, exactly 10 ml. of the benzeneisobutyl alcohol mixture is added to each, followed by 2 ml. of 10% ammonium molybdate solution. The volume is made up to the 25-ml. mark with distilled water and the Dhosohomolvhdate complex is extracted by vigorous shaking ?or at least-20 seconds. After the layers have separated, exactly 5 ml. of the supernatant organic layer is transferred into another 25-ml. volumetric flask and diluted with about 10 ml. of the sulfuric acid-methanol. Then 1 ml. of reducing agent is pipetted into the
.
PnoCmmE. For every sample two sheets (9 by 9 inches) are marked with two lines 1 inch from tw-o adjoining edges. The crossing point of these lines is the starting point in one corner. Each sheet is coiled into a cylinder and fastened with a platinum clip. A 2.~1. spot of reference standard A , which contains only pyrophosphate, is placed exactly on the starting point of one sheet. This sheet is dried, and then 5.~1. drops of the sample solution are added on the starting points of each of the two sheets. The sheets are run in basic solvent for 8 to 9 hours, during which time the phosphate species migrate a t their respective speeds along the pencil line psrdlel to the upright edge, which becomes the startine line far the second run. After the paper is dried, the platinum a i p is removed, snd the cylinder is infolded. The height of the solvent front i s measured, and the upper third of t,hnt, nnrt,ionof the ahent. _..__ ~ which ~ .has . been ~ oenetrated hv the solvent is marked as reference area. In this area, one or cwo reference soots are marked 1 inoh a m r t on the starting line for the second .
"
~~~~~
~
~
~
~
~
~
marked reference spots.' A separation in acid solvent'is run for 8 to 9 hours, and the pattern is developed. h photograph of such a developed pattern is shown in Figure 1. (The spot marked 8s "accumulated impurities from basic solvent front" consists of fluorescent material and shows up highly exaggerated in the figure.) QUALITATIVE EVALUATION. On the sheet containing reference standard A , a line is drawn through the center of the pyro spot (Figure 1). The ring and chain phosphates are identified by the aid of the reference spots; their locations are clearly shown in Figure 1. Tetraphosphate is fouhd very close to the trimeta level and pentaphosphate near the tetrameta level. For the positive identification of the slower moving hem- and heptaphosphates, a calibration curve is prepared by plotting the logarithms of the R, values-i.e., (distance moved by spot in acid Bolvent)/(distance moved by acid-solvent front) ZIS. the chain length for the ortho-, pyro-, and triphosphate-s found from the reference are&. From an extrapolation of this line, the numbers of phosphorus atoms corresponding to the logarithms of the R, values of the unknown species artre determined. The second sheet is required for recognia-
~
ANALYTICAL CHEMISTRY
1094 ing any pyrophosphate t o be found in the sample itself and for eliminating errom from incidental contamination such as fingerprints. Typical R, values obtained on solutions containing a mixture of phosphates are shown in Tahle I. The two sets of RJ values given for the acid solvent illustrate the variations to be expected from one experiment t o another. A plot of log RJ us. n, for the &&-phosphates in the aoid solvent gives a straight line, as found by Grunze and Thilo (9). SEMIQUANTITATIVE EvALuAnoN. The spots are cu%o w and mrtlysed according to the general procedure for quantitative evaluation. Because the sample weight is in the range of only 10 y of phosphorus, the reading errors of the colorimetric procedure give deviations of several per cent. Quantitative Assay of Commercial Alkali Triphosphates. A sample of 1.5 grams is dissolved in 250 ml. of distilled water and well mixed. By one-direotional chromatography in acid solvent, percentages for ortho-, pyrq-, and long-chain phosphate are Obtained. The analysis for ring phosphate is separately acCOmplished by running a two-directional separation, first in basic solvent then in acid solvent. ONE-D1RECnoN.u RUN. A sheet 9 b 2 6 inphes is laid 0ut.into the areas for blank and sample (the soli pencilled lines m Figure 2). Droplets of 5 PI. of the sample solution are applied on each z mark on the starting line; 5-MI.droplets of reference standard B m e applied st RI and Rz. Each half of the sheet represents one analysis with a common blank area of paper between. The chromatogram is run in acid hours a t room temperature. The triphosphate solvent for 2>/% fraction is cut t o include any trimetaphosphate present, a8 indicated by the trimetaphosphate reference spots (next to the starting line on Figure 2). The quantitative analysis of the
_. -..--.._ _._-_ , ~,.. ~, ..-~ triphosphate on typical sheet for one-directional quantitative m n _ _ _ I
Right half marked with dotted cuftinz linea
-
Table I.
R, Values of Phosphates Solvents
,
(Room temperature) Phoaphhata Lipeoiea Ortho howhate Pyropgosphste Triphosphate Tetraphosphate PentaDhosDhate Heaaphosphhte Heptaphoaphate Trimetaphosphate Tetrametaphosphate
Chain Length
ni BUiO
1
mivent 0.28
3 4 5
0.18 0.15 0.13
(no)
2
5
.. 7
..
0.20
"0 . 1 1
I'
Acid Solvent 0.68 0.73 0.42 0.48 0.21 0.33
::::
20:
0.09 0.06 91
"
chromatogram is carried out as described previously. To correct for hydrolysis of tri hos hate on the paper during the run, 0.3% of the phosphorus &um!as triphosphate is added far each hour of the run. The same figure is deducted from the percentage found for the pyro fraction to correct for the hydrolysis products having migrated into this area. T W O - D I ~ C T I O NRUN, A L A sheet 9 by 6 inches is prepared and marked as shown in Figure 3. Droplets of 5 @I. of sample solution and of reference standard B are placed a t x and a t RI, Rs, and Ra, respectively. The chromatogram is run in basic solvent a t 2 5 O C.for 4to5 hours. Thesheetisremovedfromthejar,dried, bent flat, and the strip carrying the reference spot R, is cut off along the dashed line in Figure 3. The reference strip is sprayed and developed. By the aid of the reference strip, the upper level of the highest phosphate fraction (trimetaphosphate) is marked on the unsprayed main sheet. The sheet is then cut a/+ inch above this level, coiled into the cylinder again, and inserted upside down without any pretreatment period for the acid solvent run, which is extended over l'/* hours. When the pattern ia developed, the trimeta area appears as a band, clearly separated from the other phosphates and located near the edge of the sheet cut off prior to the second run. The percentage of total phosphorus as ring phosphate is determined as previously described. RESULTS. Typical data found in using this procedure are summarized in Table 11. The first sample analyzed was a m k ture of highly purified a l l d i ortho-, pyrc-, and triphosphates. The result8 of four determinations show that the accuracy and reproducibility of this chromatographic procedure are ahVWS better than 1%of the total phosphorus. The second analylysis in
Tahle 11. Results of Differentia1 Analyses of Phosphates % Phosphorus Found Specie8 present I I1 I1 35.5 35. 35.03 34 4 Orthwhoaphate 34.7 35.7 35., 35.43 Pyrophosphate 29.' 29.8 29.9 Triphosphate 29.53 1.0 0.5 1.0 Sodium triphosphate, hexs- Orthophosphate 14 1.5 Pyrophosphate 1.2 hydrate. rearystailired b 97.5 98.2 97.6 Triphosphate 0.0 0.0 Commeroisl sodium tri- Orthophosphate 3.8 3.7 phosphate, high temp- PyroDhosDhhte 94.0 94.0 Triphosphate erature nse 0.8 0.8 Long-chain phosphate Trimetnphowhate 0.9 0.8 Commercial sodium tri- Orthwhomhhte 10.9 10.4 phosp+&te,low tempera- Fmophosphhte 87.2 87.2 Tri- trimetaphoaphate ture *mea 1.4 1.1 Long-chain Dhosphate 0.1 0.3 Erperimentsl sodium tri- Oitlio~hosphhte 3.2 3.5 Pyrophosphate phosphate 95.3 96.5 Triphoaphate 0.0 0.0 Lon=-chain phosphate Trimetaphosphate 0.3 0.3 Experimental sodium tri- Orthwhowhate 4.5 4.7 Pyrophosphate phosphate 94.2 94.0 Triphosphate 0.3 0.3 Long-chain phosphate Trimetaohosohsts . . * The ortho and pmo content of the NsrP1010.6HI0and NaiP10i used 8 8 atarti determined by ion exchange technique (24). ,The figures given m column 3 &re 08 weights and eaaot a8887 of the starting ma,tensls. b Figures in oolumn 3 were obtained by ,on exchange (24); Beukenkamp, Rieman. ana LmdenD&llm slso describe an ion eaehanse procedure. (*)0 Not analysed for trimetaphosphate. Ph"."h.'. .."lllll"l
~
sample Pure phosphate miaturea
^
^
V O L U M E 2 8 , NO. 7, J U L Y 1 9 5 6
1095
Table I1 demonstrates that the paper chromatographic procedure gives the same results as chromatography in an ion exchange column. The other analyses are examples of the application of this method to commercial and experimental samples of sodium triphosphate. Triphosphate and trimetaphosphate cannot be separated in a short one-directional chromatographic run in the acidic solvent. The triphosphate fraction always shows some trailing effect which interferes with a clear separation even in a 5-hour run.
R,
Figure 3. Sheet for quantitative determination of ring phosphates by twodirectional separation of sample bands
All trimetaphosphate is definitely included in the triphosphate area if this zone is cut just below the level of the triphosphatetrimetaphosphate reference spot pair a t the margin of the sheet (Figure 2 ) . Any tetraphosphate present would also fall on this area. If a short-chain glass is being assayed by this procedure, it must be kept in mind that (1) tetraphosphate as well as trimetaphosphate is included in the value for triphosphate, and ( 2 ) pentaphosphate as well as tetranietaphosphate will show up in
Table IV.
both the triphosphate and the nonmoving fraction (hexaphosphate and longer chains). The correct way to analyze for those phosphate species is to use extended separations, in which hydrolysis correction values are employed for each species. Results of the two-dimensional procedure for the determination of ring phosphates are shown in Table 111. The solutions were obtained by diluting a trimetaphosphate standard, which was found to contain 90 5 7 , phosphorus as trimetaphosphate by chromatographic analysis, with varying amounts of triphosphate, free of any trimetaphosphate. If more than a trac.e of nonmoving, long-chain phosphate is found in the one-directional chromatographic run, the whole paper area down to the starting area must be included for the determination of total phosphorus in the tiyo-directional chromatogram. In this case, it is recommended not to let the solvent front in the basic run rise higher than 5 inches above the starting line. This brings the short-chain phosphates in the second run very close to the starting line of the first run, back to the area where the long-chain phosphates are located. Any tetrametaphosphate present migrates slower than trimetaphosphate in the basic run, and also slightly slower than the trimetaphosphate in the acid run. Because these two rune are in opposite directions, both ring phosphates are located in the same area after the two runs. Separation could be accomplished hy running a third separation in acid solvent after cutting off the chain phosphate fractions.
Table 111. Determination of Trimetaphosphate in Presence of Triphosphate and Minor Amounts of Ortho- and Pyrophosphate % Phosphorus as Trimetaphosphate Calcd. from composition of Found materials used 52.0 51.4 27.0 27.6 14.3 7.1 I.6 3.7 3.7 2.4 1.9 1.2 0.95
‘2.3
Differential Phosphate Analyses of Detergent Formulations
% Phosphorus of Total Phosphorus Phosphate Phosphates I n detergent % Species alone mixture Sodium triphosphate hexahydrate, Orthophosphate 0.4 0.2 32.3;tetrasodium pyrophosphate, Pyrophosphate 31.5 31.4 12.4; sodium carbonate mono- Triphosphate 67.5 68.0 hydrate, 12.3; sodium silicate, No. Long-chain phosphate 0 5 0.4 9 b , 38.5; Sterox CDC, 4.5. Sodium triphosphate hexahydrate, Orthophosphate 0.4 0.4 0.4 31.1; tetrasodium pyrophosphate, Pyrophosphate 38.1 37.8 36.9 16.1’sodium sulfate 12.3. sodium Triphosphate 60.9 61.3 62.3 silicAte, No. 9 b, 2O.i; Sahtomerse Long-chain phosphate 0.6 0.4 0.4 No. 3C. 17.7; minor ingredients (including brightening agent and sodium carboxymethylcellulose), 2.3. Sodium triphosphate 40. sodium orthophosphate 0.2 0.5 0.4 carbonate, 25; sodium ’silicate, N Pyrophosphate 7.2 7.5 7.3 Brande, 20; Sterox CDC. 14; Triphosphate 92.0 92.3 92.6 brightening agent plus perfume Long-chain phosphate 0.2 0.0 0.0 plus sodium carboxymethvlcellulose. 1. Sodium triuhosohate. 20: tetraso- Orthoohosohate 0.2 0.9 0.9 51.7 50.8 Pyrophosphate 51.4 48.0 Triphosphate 47.7 47.6 Long-chain phosphate 0.2 0.2 0.0 Detergent Formulation,
I’
IIa
IIId
IVd,f
lose, 1. Ortho and pyro content of the SarPaOio.6HzO and h’arPnO7 used as starting materials were determined by ion exchange technique ( 2 5 ) . Long-chain phosphate content of the N a r P ~ Owas ~ determined b y paper chromatography. Figures given under “Phosphates alone” are calculated from weights and assays of starting materials. b E. I. d u Pont de Nemours & Co. C Monsanto Chemical Co. d Sodium triphosphate used as starting material was assayed by paper chromatographic technique. Philadelphia Quartz Co. I Sample of pyrophosphate used as starting material not assayed for ortho content. High value for ortho found in detergent mixture indicates t h a t pyrophosphate contained a small amount of orthophosphate. a
1096 100
ANALYTICAL CHEMISTRY
+.-
. ..7..-.,"..-,,drolysis of tion of the phosphomolybdate complex between aqueous and triphosp1i:tte. nonaqueous phayes seems to be replaced by a distribution aniorig The procedures recommended here keep the separating rriiis t Iiree phases: cellulose, aqueous phase, and organic solvent misin the ac-id solvent as short a3 possible. I t was found that after t ire. The effect is a deficiencl- of phosphorus in the organic sol2l/. hokirs a t 25' C., complete separation of ortho-, pyro-, tri-, vent phase, which amounts to a definite percentage of the phosarid long-chain phosphates is accomplished (Figure 5 ) . The rephor~isfor every unit of cellulose surface present. These conispective zones can easily be cut and the corrertion values for pyroplications are circumvented in routine work by attributing equal and triphoyphate are relatively sm:tll ( < l fi), so that a slight piper areas to all phosphate zones, carrying along all of the fract1evi:Ltion iii room temperature during the ruii does not cause an tions of one analysis in a group to provide equal degrees of macera:ipgrrcaisble error in the corrrction. tion of the paper, and determining only the ratios of each fraction to the total. Microgram quantities of phosphorus in each fracLITERATURE CITED tion cannot be measured as accurately when the paper is present Bell. R. S . . Audrieth. L. F., Hill, 0. F., t n d . Eng. Cheni. 44, during the extraction as they can be in the procedure which in568 (19521. . ~ . cliides a separate elution of the phosphate from the paper prior B e u k e n k a m p . J.. Rienian, W., 111, Lindenhaurn, P.. .%SAL. t o the extraction of the phosphoniolybdate complex. CHEM. 26, 505 (1954). S:itisfactory separation of the chain phosphates can be obBrovkina. I. d.,Zhur. Obshchei Khim. 22, 1917 (1952). C r o w t h e r , J., ANAL.CHEM.26, 1383 (1954). t:iiiied only in acid chromatographic solvent mixtures. Partial E b e l , J. P., Bull. SOC. chim. France 20, 991. 998 (1953). hydrolysis of the condensed phosphates occurs, therefore, during Ebel, J . P., M i k r o c h i m . Acta 1954, 679. u chromatographic separation; the resulting hydrolysis products Green, J.,I n d . Eng. Chem. 42, 1542 (1950). are located on the chromatographic sheet according to the reGriffith. E. J.. J . Am. Chem. SOC.76, 5892 (1954). G r u n a e , H., Thilo, E., Sitz. ber. deut. A k a d . Wiss. Bediu. t
