DE2754252C2 - - Google Patents

Description

The invention relates to powders for chromatography, in particular the size exclusion chromatography, and the Zu Composition of the used in this chromatography Powder.

The US-PS 35 05 785 describes superficially porous Microspheroids having a mean diameter in the Range from 5 to 500 microns and have an undurch casual core and a variety of envelop the core the monolayers of colloidal inorganic Particles of mean size in the range of 0.005 to 1.0 μm exist. The US-PS 38 55 172 describes micro spheroids, which are porous throughout and have a mitt Larger particle diameter in the range of 0.5 to 20 microns respectively. They consist of colloidal inorganic refractory particles with a mean diameter in the Range of 0.005 to 1.0 μm.

The use of microspheres of this type for chromatography, especially size exclusion chromatography, is well known. In this application, porous microspheroids are used as filler for the separation zone of the chromatograph. They effect the separation of the components of a sample based on differences in the hydrodynamic size of the components. The molecular weight (MW) of the components can be calculated as a function of hydrodynamic size. A graphical representation of the molecular weight fraction eluted at a given retention volume (V _R ) for a given fill material shows that for a given pore volume in the fill, certain molecular weight fractions are completely excluded due to their large size and certain molecular weight fractions completely due to their small size to run. Between these two extremes lies a range of molecular weight fractions which are preferably retained or retarded by contact with the porous particles; Materials containing these molecular weight fractions can be fractionated by this particular filler.

The actual working relationship in size Final chromatography is the molecular weight calibration curve, which is usually a logarithmic graphic Representation of the molecular weight as a function of Retention or retention volume. Molecular weight Calibration curves characteristically have a essential linear part so that the molecular Weight of a retained fraction of a sample can be determined exactly when the retention volume for this particular molecular weight fraction in linea ren part of the molecular weight calibration curve occurs, and less accurate, if it is outside of this linear Area occurs. Have molecular weight calibration curves characteristically linear parts that extend across about two decades in the log. molecular weight scale for a single pore size. To one Calibration curve with a linear part, which is over more than two decades of the molecular weight scale usually one uses a chromatogra phische separation zone, the be of numerous columns be each of which has a different pore size. As in "Know More About Your Polymer", published in 1976 described by Waters Associates, Milford, Mass.,  combined to the extension of the linear range the molecular weight calibration curve in such a way that materials that cover a wide range of molecules large-size fractions contained, separated and nachge may be four or five columns, each because they have molecular weight calibration curves whose linear parts overlap one another.

Unfortunately, the expected linear molecular weight occurs do not open. The straight-line part of the molecular weight calibration curve for the combined particles be enlarged in this way, but the maximum only seem to be about three decades. This is common less than the molecular weight range found in nor can be found sample compositions.

The invention relates to a powder for Chromatographs, with which another area of Gerad achieved in his molecular weight calibration curve and the disadvantage of using multiple columns overlapping linear parts of the calibration curve is avoided. This powder contains a lot number of porous macroparticles that are chosen that a bimodal pore distribution is present, wherein the average pore size for each Ver division mode is such that the rectilinear portions of the Molecular weight calibration curves for each pore size in the bimodal distribution is essentially not over cut, and every distribution mode such a pore volume has that the above-mentioned rectilinear Parts are essentially parallel. The here ge needed phrase "mean pore size" refers to the volumetric mean pore size. To the maximum Range of the straight-line portion of the molecular weight To reach calibration curve, the pore sizes of the Types of bimodal distribution of about one order of magnitude apart. The term used here  "bimodal pore distribution" is not to be understood that the use of more than two types of part size distributions is excluded, as long as adjacent distributions are substantially parallel linear, non-intersecting parts of their Have calibration curves, wherein the average pore volumes each of the two adjacent distributions by approximately an order of magnitude are separated.

The macrotext suitable for the purposes of the invention For example, refractory particles may consist of Be silica or alumina, or they may consist of crosslinked polymer gels. In the before zugten embodiment, the macroparticles are refractory Macroparticles, mainly of silica consist, the component of the bimodal pore distribution ment with the smaller mean pore diameter 30 to 60%, preferably 40 to 60%, especially 40 to 55% of the total pore volume of macroparticles in the Powder makes up and a share of 45 to 55% especially is preferred while the rest of the entire pores volume through the component of the bimodal pore ver division with the larger average pore diameter is contributed. The powder can be from a lot number of macroparticles, each containing a has bimodal pore distribution, or it may look a variety of macroparticles with the same pores distribution in each particle in combination with a Variety of macroparticles with a different pore ver division.  

The invention will be described below with reference to FIGS Illustrations described.

Fig. 1 shows a representative calibration curve of the molecular weight as a function of the retention volume in the log. Scale.

FIG. 2 shows a calibration curve for a separation zone consisting of six different particles with different pore sizes . FIG .

Fig. 3 is a schematic representation of a liquid keitschromatographen with the injection point 12 for the carrier liquid, the separation zone 13 and the detector 14 and in particular shows separation zones consisting of 1 and 2 separate columns.

Fig. 4 shows a representative calibration curve for bimodal and polymodal powders.

Fig. 5 shows schematically partially cut away an embodiment of a completely porous macroparticle with bimodal pore distribution.

Fig. 6 shows schematically and partially cut away a second embodiment of a fully porous macroparticle with bimodal pore distribution.

Fig. 7 shows schematically and partially cut away an embodiment of a superficially porous macro particle with bimodal pore distribution.

FIG. 8 shows a mercury intrusion plot for particles as shown in FIG .

FIG. 9 shows a comparison of the calibration curve obtained using two of the particles having non-intersecting particle size distributions shown in FIG. 2 with a calibration curve using five of the particles shown in FIG. 2 and their particle size distributions all overlapped, was obtained.

Fig. 10 shows a calibration curve obtained by using the bimodal particles shown in Fig. 6.

For size exclusion chromatography, a chroma tograph as shown schematically in Fig. 3 is used. The material to be separated is sprayed at an injection point 12 into a carrier liquid flow and injected under pressure through a chromatographic separation zone 13 , consisting of the powder according to the invention, to a detector 14 . When passing through the separation zone, the materials in the support medium stir the filler in the separation zone, retaining them for a time characteristic of their molecular weight (MW) . After some time, after a larger volume of the carrier medium has passed through the chromatographic column, the material temporarily retained by the filler material is eluted from the column. The detector determines when each component of the material leaves the separation zone.

The output signal of the detector is a characteri stic peak, as shown schematically in Fig. 4 Darge is below.

As separation zones are for the size exclusion Matography in general uses columns with porous particles, as described in US-PS 35 05 785 and 38 55 172, or more recently with the macroporous microspheroids disclosed in US Patent application 6 39 111 (15.6.1976) be described ge are filled.

For the use of such fillers, a typical relationship of log. (MG) (a function of the hydrodynamic radius of the solute (solute hydrodynamic radius)) depending on the retention volume (V _R ) represented by the single solid line on the left side of Fig. 1. The limiting retention volume at point A is known as the total exclusion volume determined by the maximum pore size available for permeation through the solutes that are completely rejected from the eluate of the internal pore volume (internal porosity elute) at that return volume becomes. The dissolved substances corresponding to this molecular weight and a higher molecular weight are not fractionated by the system. The point B represents the volume of the species that completely penetrate the inner pores of the filling material, and is known as total permeation volume. Materials corresponding to this and a lower molecular weight can thus practically not be fractionated by this separation system. The difference between the holding volumes A and B represents a partial permeation of the solutes, and within this volume the separation takes place. The difference between the retention volume at B and the retention volume at A is a function of the total internal pore volume of the filling material. Between the retention volumes at A and B is an approximately linear range of the log of log. MG depending on the retention volume (points C to D) represented by the following equations:

V _R = C ₁ - C ₂ log. MG (1)

and

MG = D ₁ e - D ₂ V _R (2)

C ₂ is the slope of the rectilinear part of the calibration curve (in ml / decade MW ) , and C ₁ is the length of this straight-ligne part. To obtain information about the molecular weight from this calibration curve, experimental graphograms and the above equation 2 are used. D ₁ denotes the portion of this linear part of the calibration curve and D ₂ their inclination. These equations are well known to those skilled in the art and are widely used to characterize macromolecules.

The additive characteristics of two equal columns used in size-exclusion chromatography are well known. As shown in Fig. 1 Darge, the joining of two identical columns (same particles, same length) with identical calibration curves, which are represented by the two solid lines, equivalent to a doubling ment the length of a single column. As illustrated in the figure, by combining these two columns, the total available pore volume is increased, thereby increasing the range of retention volume between total permeation and total exclusion but maintaining the same molecular weight fraction range. As shown in Fig. 1, when two columns are joined, the range of the molecular weight fraction remains about 3,000 to 80,000, although the retention volume is doubled. The calibration curve for the combination of the two columns is shown by the dashed curve. The additive function that describes this relationship is

The polymer fractionation is usually carried out with Füllun gene, which have the widest possible pore size distribution. This is usually achieved by connecting several columns of different pore size and thereby forming a separation system that detects the molecular weight range of interest. Figure 2 shows a series of molecular weight calibration curves for six different chromatographic separation zones, each filled with porous silica particles of different pore sizes. The name and average pore volume for these six particles are listed in the following table.

designation Pore size (Å) 1 PMS-50 60 2 PMS-300 125 3 PMS-600 195 4 PMS-800 300 5 PMS-1500 750 6 PMS-4000 3500

These particles were prepared according to the methods described in US Pat 6 39 111 (15.6.1976) and in US-PS 37 82 075 prepared method described.  

The bar graphs on the right in FIG. 2 indicate the straight line region of each calibration curve. In order to achieve a linear combined calibration curve spanning a molecular weight range of 10³ to 10⁶, a combination of six columns would normally be used, each consisting of the individual particles corresponding to the six diagrams.

According to the invention, the relationship given in Equation 3 is exploited to improve the accuracy, versatility and suitability of the size exclusion process. This relation predicts a phenomenon not previously recognized, namely that in order to obtain a linear relationship of log. MG to retention volume a series of columns with significantly overlap the straight Molekulargewichtsfraktionierungsbe rich (ie straight parts) is not used to who should. Instead, columns having only two pore sizes chosen so that the rectilinear parts of the curve of molecular weight do not intersect depending on the retention volume should be used. As a result, a much larger linear range is obtained in the calibration curve. As representatively illustrated in Figure 4, a polymodal pore distribution in the separation zone gives a narrow rectilinear portion on the molecular weight oak curve, while a bimodal distribution gives a much larger linear portion. The calibration curve for the polymodal distribution does not encompass the total molecular weight distribution of the sample within its rectilinear range, whereas in the calibration curve for the bi-modal distribution.

The advantage of using chromatographic columns with bimodal pore distribution, whether connected to columns of uniform pore size or columns containing a physical mixture of particles having two pore sizes, is therefore evident from FIG . Molecular weight calibration curves of the type exhibited by the bimodal pore size distribution are particularly preferred when attempting to characterize a polymer having the type of molecular weight distribution shown below in the graph.

FIG. 9 shows a quantitative comparison of a polymodal pore size distribution with the system of the bimodal pore size distribution . This figure shows a polystyrene calibration curve for a polymodal and a bimodal separation zone. The group of columns to be det to gen hervorzubrin the polymodal distribution of the USAGE is filled with a filling material, which is designated in Fig. 2 having 1, 2, 4, 5 and 6. The individual columns have substantially overlapping calibration curves as in the usual mode. The approximately straight line region of the calibration curve (the dotted line is the straight line fit) of this combined set of wide pore distributions comprises only 2.5 molecular weight decades. In contrast, the bimodal distribution shown in Figure 9, obtained by joining columns of only two pore sizes (those of particles 1 and 5 in Figure 2), gives a straight line molecular weight calibration curve that spans more than four decades of the molecular weight.

To achieve these surprising and improved results, the individual calibration curves for the two pore sizes used in the bimodal distribution must not overlap. This is achieved by choosing Part chen with the appropriate pore size. The median pore sizes of the bimodal distribution should be about one order of magnitude apart. This bimodal path gives linear calibration curves covering up to five decades of the molecular weight range. With a trimodal arrangement of the same type, rectilinear parts of the calibration curve covering up to seven decades of the molecular weight range could be obtained. Apart from molecular weight calibration curves that do not overlap, the internal pore volume of the two distributions must be such that the rectilinear portions of the calibration curves are substantially parallel. The term "substantially paral lel" states that the shapes of the rectilinear parts of the calibration curves need not be exactly parallel, provided that some deviation from the straight-line speed can be accepted. For example, Fig. 9 shows that the intersecting polymodal calibration curve representing the prior art is far from being straightforward over the predicted range. When about 30 to 60%, preferably 40 to about 60%, more preferably about 40 to 55% and, most preferably, about 45 to 55% of the total pore volume of the macroparticles in each separation zone in the component of the bimodal pore distribution with the smaller mean Pore size are keep ent, while the remainder is attributable to the component with the larger average pore size, the straight-ling parts of the individual calibration curves are substantially parallel. Fig. 10 illustrates the deviation from the straightness in the calibration curve when the ratio of the pore volumes is 40:60. However, in the most preferred embodiment, each component of the bimodal pore distribution should account for about 50% of the total pore volume of the macroparticle in the separation zone to reduce the deviation from straightness in the calibration curve.

The best results are known to be obtained when filling materials with very narrow pore size distribution are used. The pore size distributions of each bimodal system should be 1.0 or less (2 σ ), as shown by the usual log normal graphs of mercury porosimetry. Areas of 0.5 (2 σ ) are preferred. Within these ranges, the pore size distribution is an insignificant factor in determining the D ₂ value of the calibration curve, and the internal volume of the particles is decisive in determining the D ₂ value of the calibration curve. When the pore size distribution is larger than the above values, the correlation of pore size distribution plus internal volume determines the slope of the calibration curve.

The applied according to the invention bimodal pore distribution can be achieved by one of two methods. The bimodal pore distribution can be adjusted by a variety of microparticles, all of which have a bimodal pore distribution. In this case, a single column as shown in the upper part of Fig. 3 may be used. However, the bimodal pore distribution can also be adjusted by using a plurality of macroparticles having a uniform pore distribution and a plurality of macro particles having a different pore distribution. Although particles with different pore size distributions can be mixed in one column, the filling of these columns is less convenient. It is best to use two or more columns, each filled with particles of a certain type.

Individual particles having the pore size desired to achieve the bimodal pore distribution may be prepared by the methods described in the aforementioned patents and patent applications. Polymer gels, alumina, and the broad range of refractory particles disclosed in these patents and patent applications may be used, but silica is the preferred material, particularly for chromatographic separations. Particles having a bimodal pore distribution may be either completely porous or superficially porous particulates. By the term "macroparticles" as used herein is meant the composite macroparticle (either completely or superficially porous) having a mean diameter in the range of about 0.5 to 500 microns. The completely porous particle is shown in FIG . This macroparticle 15 has an average diameter of about 0.5 to 500 microns. Preference is given to macroparticles having a mean diameter of about 5 to 50 microns. The macroparticle consists of a plurality of microparticles 16 each having a mean diameter in the range of about 0.005 to 1.0 μm, preferably about 0.005 to 0.5 μm. The individual microparticles in turn consist of a plurality of ultramicrogranules 17 having a mean diameter in the range of about 1.0 to 30.0 nm, preferably 2 to 20 nm. Micropores 18 are present between all microparticles and micropores 19 between all microparticles. In general, these particles may have any shape, but the spherical shape is preferred so that the macro particles are in fact macrobeads, the micro-microspheres microparticles and the ultra-micro particles are ultra-microspheres. The spherical shape of these materials improves their performance in chromatography columns.

Alternatively, as shown in Fig. 6, the wholly porous macroparticle 15 may be composed of a core 20 consisting of a plurality of ultramicrogranules 21 having a mean diameter in the range of about 1 to 30 nm, and a skin consisting of a plurality of microparticles 22 having a diameter in the range of about 0.1 to 1.0 microns, or preferably 0.1 to 0.5 microns exist. The completely porous Makroteil surfaces prepared by the methods known today have preferably a diameter in the range of about 0.5 to 50 microns.

An embodiment of a superficially porous macro particle is shown in Fig. 7. This macroparticle 22 has a diameter in the range of about 0.5 to 500 .mu.m, preferably from 5 to 50 .mu.m, and consists of an impermeable macrokernel 24 and a sheath of a plurality of same monolayers of coextensive colloidal inorganic microparticles 25 , which together are connected and surrounded the core. Each microparticle has a mean diameter ranging from about 0.005 to 1.0 μm, or preferably from 0.1 to 0.5 μm, and constitutes about 0.2 to 25% of the total volume of the macroparticle. The microparticle may be similar to the microparticle shown in FIG. 5, which consists entirely of ultramicrogels, or the microparticle shown in FIG. 7, which may consist of an impermeable microkernel 27 and a shell of a plurality of like monolayers of the same colloidal inorganic ultramicrogranules 28 standing, which are connected to the core and surround it.

In both cases, ie the fully porous and the superficially porous particles, the pores between the individual microparticles in the macroparticle are referred to as macropores 30 , which are a type of bimodal pore distribution, while the pores between the individual ultramicroparticles are referred to as micropores 31 , which represent the other type of bimodal pore distribution. According to the newer terminology, the pores of the size referred to here as "micropores" are referred to as "mesopores".

Example 1

The production of "pellicular" particles with bimodal pore size distribution will be described below. Such a construction is shown in FIG .

75 g of a chromatography support of superficially porous Silica (<37 μm) was treated with 800 ml of 0.5% cleaning solution for laboratory equipment gently stirred for 30 minutes. The Excess solution was removed by decantation, whereupon was washed with distilled water. These measures were repeated seven times. The resulting powder was then on a filtered coarse sintered glass filter and dried in air. The dry powder was then placed in a coarse sintered glass filtered and dried in air. The dry powder was then passed through into a coarse sintered glass funnel of 7.6 cm Knife and with 100 ml of a 0.5% solution of an anti statikmittels and mold release agent (poly (diethylaminoethyl ethyl methacrylate) acetate) for 5 minutes. The treated ones Beads were filtered off and then distilled twice with 200 ml washed water and in the funnel under reduced pressure Pressure dried.

The beads were then mixed with 100 ml of 10% silica sol, Herge prepared from ammonia-stabilized silica sol, 24 nm (Silica particles of about 140 Å particle size), (125 g 30% silica, ammonia stabilized silicon dioxide sol, 24 nm, with distilled water to 400 g ver thin). The mixture of pearls and silica sol was Stand in the funnel for 15 minutes with frequent gentle stirring calmly. The excess silica was then filtered off triggers and the received wet cake four times before careful slurrying with about 400 ml of tap water and fil washed. The cake was then dried in the oven Leave filters under vacuum in the air. This material  was then one hour at 150 ° C in a warming cabinet with air whirled through. A small sample was taken for measurement taken from the surface.

The treatment described above with the above Antistatic agent and mold release agent and the silica sol repeated three more times, leaving a crust from the pebbles sol ultramicroparticles of 140 Å particle size on top surface of the 2000 Å silica microparticle, originally the crust of the particles of chromatogrophy Carrier formed. The final particles were dried and heated for 2 hours at 650 ° C to the organic intermediate burn-out layer and the particles to a mechanical to sinter stable state. This sintered sample was then 2 hours in a large excess of 0.001 molar ammo ammonium hydroxide with frequent stirring. The part were then twice with a large excess of washed by decantation on a distilled water coarse sintered glass funnel, dried in air and 2 hours in a circulating air bath at 150 ° C heated. The final material was made with stainless steel sieves dry sieved, with 45 g of a fraction of a particle size of <38 microns were obtained.

The surface of the Pro. Obtained during the synthesis steps was measured by the nitrogen flow method. The the following results were obtained:  

The pore measurement in this sample by mercury porosimetry revealed three breakpoints in the mercury intrusion curve, one at about 10 microns, which is the penetration of mercury between the Single particle represents a break point at about 0.07 microns (700 Å), which is the macropores between the sol microparticles in the Represented crust of the original chromatography vehicle and a break point at about 0.006 μm (60 Å), which is the pores between the 140Å ultramicrosol particles following the method described here in many layers on the original chromatography carrier were applied. On the bimodal pore distribution accounted for the following volumes:  

Macropores (700 Å) 0.011 cc / g Macropores (60 Å) 0.014 cc / g

These values show that the final particles are the desired bimodal pore design with a size difference of about a decade between the two different pore sizes and had approximately equal pore volumes for each pore size.

example 2

Particles of the type shown in Figure 6 can be prepared as follows: 15 g of porous silica microspheres (PSM-40, pores of 47 Å) prepared according to Applicant's US Patents 3,782,075 and 3,855,172 have been designated 200 treated with 0.001 molar ammonium hydroxide, allowed to stand for 10 minutes with occasional stirring, and centrifuge in a 250 ml polyethylene bottle for 2 minutes (from the beginning) at about 2000 rpm. The clear supernatant was decanted. To the wet cake was added 100 ml of a 0.5% solution of the above antistatic agent adjusted to pH 7 with ammonium hydroxide. The system was cautiously slurried and then allowed to stand for 10 minutes with occasional gentle stirring. The resulting mixture was centrifuged for one minute in the manner described above. The excess solution of the antistatic agent was decanted. The wet cake was washed twice with 200 ml of distilled water (adjusted to pH 7 with ammonium hydroxide) by gentle slurrying, centrifuging for 1 minute and decanting.

To these treated particles was added 50 ml of one to pH 8 adjusted 5% (weight) silica sol mixture of 2000 Å given. (The sol can after the W. Stober, A. Fink and E. Bohn in J. Colloid, Inter. Sci. 26 (1968) 62 described Ver  be made). The mixture was carefully slurried and occasionally stirred for 10 minutes. This mixture was centrifuged in the manner described above and decane advantage. The excess sol was retained. The coated beads were then distilled twice with 200 ml Littered water (pH 7) by slurrying, centrifuging and Washed decanting. The at the second wash at this Treatment decanted liquid was clear. The wet cake was then on a 3 micron filter (polycarbonate disc membrane) filtered and 2 hours in a warming cabinet with air circulation dried at 150 ° C. The sample was then imbibed for one hour Muffle furnace fired at 700 ° C. A small part of this Material was examined under the scanning electron microscope. This was an excellent covering of the surface of the ur nascent beads with the silica sol of 2000 Å particle size detected. No uncovered spots were on the particles recognizable.

After the fired silica particles are heated overnight in 0.01 molar hydrochloric acid had been hydrolyzed and the acid had been removed by washing with distilled water, a second layer of 2000Å silica sol was applied to the PSM Particles applied in the manner described above. The Material was redone with the above antistatic agent and then with the Å sol (25 ml "fresh" sol plus recovered excess sol from the first treatment) treated in the manner described above. The test of this Material with the scanning electron microscope showed that the second coating was layered in the desired manner. Just very few bare spots were visible on the beads, and only very little bridging of particles was noted.

A third, fourth, fifth and sixth treatment of the beads was essentially in the same manner as above  described, performed to the desired crust of pebbles Sol particle of 2000 Å diameter on the particles trainee the. These treated beads were at 750 ° C for one hour burned and in the manner described above by treatment rehydrolyzed with dilute acid. The investigation of final beads with the scanning electron microscope gave good Covering, however, it was not possible to determine the exact thickness of the desired, superficially porous crust to recognize.

The results of measurements of pore volume by mercury intrusion shown in Fig. 8 show that the pore volume of the larger pores of these particles accounts for about 40% of the total pore volume and the volume of the smaller pores about 60% of the total pore volume. The calibration curve of log. Molecular weight as a function of the retention volume for an acid of these particles of 25 cm length and 0.62 cm internal diameter is dargestelllt in Fig. 10. Due to the difference in the internal volumes occurring in these distribution modes, there is some deviation from the straightness.

Claims (15)

1. Powder for chromatographic separations, from a Variety of separate porous macroparticles, each of which a mean diameter of 0.5 to 500 microns and a bimo dale pore size distribution, wherein the average pores sizes of the components of the bimodal distribution by about one Magnitude are different and on the component of the bimodal distribution with the smaller mean pore size 30 to 60% of the total pore volume and to the component of bimodal distribution with the larger average pore size 70 up to 40% of the total pore volume omitted. 2. Powder according to claim 1, characterized in that on the Component of the bimodal pore size distribution with the small average pore size 40 to 55% of the total pore volume and to the component of the bimodal distribution with the larger mean pore size 45 to 60% of the total pore volume omitted.   3. Powder according to claim 2, characterized in that on every component of the bimodal pore size distribution 45 to 55% account for the entire pore volume. 4. Powder according to claim 1, characterized in that the Macroparticles superficially porous macroparticles with a impermeable core and a sheath of a variety of same simple layers of touching and the core surrounding colloidal microparticles are a through have from 0.005 to 1.0 microns and 0.2 to 25% of the total Make out volume of macroparticle. 5. Powder according to claim 4, characterized in that the Microparticles have a diameter of 0.1 to 0.5 microns and the Macroparticles have a diameter of 5 to 50 microns. 6. Powder according to claim 5, characterized in that the Macroparticles mainly consist of silica and on the component of the bimodal pore size distribution with the smaller mean pore size 40 to 55% of the total pores volume and the component of the bimodal pore size ver division with the larger mean pore size 60 to 45% of the total pore volume omitted. 7. Powder according to claim 6, characterized in that on every component of the bimodal pore size distribution 45 to 55% the total pore volume omitted. 8. Powder according to claim 1, characterized in that the Macroparticles are completely porous and each macroparticle consists of a large number of microparticles, one through have from 0.005 to 1.0 microns.   9. Powder according to claim 7, characterized in that the Macroparticles have a diameter of 5 to 50 microns and the micro particles have a diameter of 0.005 to 0.5 microns. 10. Powder according to claim 9, characterized in that the Macroparticles mainly consist of silica and on the component of the bimodal pore size distribution with the smaller mean pore size 40 to 55% of the total pores volume and the component of the bimodal pore size ver division with the larger mean pore size 60 to 45% of the total pore volume omitted. 11. A powder according to claim 10, characterized in that on every component of the bimodal pore size distribution 45 to 55% the total pore volume omitted. 12. Powder according to claim 1, characterized in that the Macroparticles are completely porous and have a core of one Variety of ultramicrogels with a diameter of 1 to 30 nm and a shell of a plurality of microparticles with have a diameter of 0.1 to 1.0 microns. 13. A powder according to claim 12, characterized in that the Macroparticles have a diameter of 5 to 50 microns and the micro particles have a diameter of 0.1 to 0.5 microns. 14. A powder according to claim 13, characterized in that the Macroparticles consist of silica and on the compo of the bimodal distribution with the smaller mean Pore size 40 to 55% of the total pore volume and on the Component of the bimodal distribution with the larger pore size 60 to 45% of the total pore volume omitted.   15. Powder according to claim 14, characterized in that on every component of the bimodal pore size distribution 45 to 55% the total pore volume omitted.