Maximum sample volume, relation

Figure 1. Curves Relating Maximum Sample Volume to Column Diameter for Columns of Different Length Packed with Particles 3 p in...

In a packed column the HETP depends on the particle diameter and is not related to the column radius. As a result, an expression for the optimum particle diameter is independently derived, and then the column radius determined from the extracolumn dispersion. This is not true for the open tubular column, as the HETP is determined by the column radius. It follows that a converse procedure must be employed. Firstly the optimum column radius is determined and then the maximum extra-column dispersion that the column can tolerate calculated. Thus, with open tubular columns, the chromatographic system, in particular the detector dispersion and the maximum sample volume, is dictated by the column design which, in turn, is governed by the nature of the separation. 

Employing equation (1), curves relating maximum sample volume to the capacity ratio of the first eluted peak for different separation ratios were calculated and constructed and the results are shown in Figure 2. 

Figure 2. Curves Relating Maximum Sample Volume to the Capacity Ratio of the First Peak for Different Separation Ratios...

What happens when the sample injection volume constraint is removed Calculations can be made from the data presented by Cooke et al. (25). For these calculations, the data required is that relating to the maximum sample volumes that can be injected on the various columns while a given number of theoretical plates is maintained. This data, shown in Table IV, was calculated by using eq 3 ... 

The concept of maximum sample volume as it relates to miniaturization can be illustrated as follows, assuming that both a conventional analytical column (4.6 mm I.D.) and a narrow-bore column (2 mm I.D.) have equal efficiency, length, and porosity. To switch a method from the analytical column to the narrow-bore column and still maintain optimum performance on the narrow-bore column, Eq. (8.1) may be rewritten as... 

It is seen from equation (15) that the maximum overload volume is linearly related to the (k ) value of the first eluted solute of the critical pair, the function (a-1) and the column dead volume, Consequently, the larger the column, either in length and/ or radius, the larger the sample volume can be, This assumes that the column is of such a size, that it can be efficiently packed with practical techniques and that the particle size of the packing is chosen such that the pump pressure available can provide the necessary mobile phase flow-rate. 

Although chromatography is a separation process, dilution occurs during the process of separation. The small sample volume that is injected onto the head of the column disperses in the mobile phase during passage through the column. The dilution factor can be expressed in terms of the maximum peak concentration, Cmax, and is related to the injected sample mass, ms, according to... 

From Fig. 3, it appears that the specific surface area of the disordered DWM materials remains very high till 800°C. Beyond this tenperature, for sample B for instance, its value decreases from 800 to 20 mVg if calcination ten rature is raised from 800 to 1000°C. Whatever the hydrothermal treatment conditions of the synthesis are, the thermal resistance of the materials is similar. Even at 1000°C, the recovered materials exhibit a type IV isotherm, characteristic of mesoporous compounds. A part of mesoporosity is thus maintained with quite a narrow pore size distribution, but the maximum adsorbed volume is sharply reduced. This is in accordance with the very broken appearance of the particles observed by SEM. Thermal stability of these disordered materials is, however, very superior to MCM-41, whose structure does not resist beyond 600°C. This behaviour can be related to the different preparation method that affords compounds with a different structure and also thicker walls. 

Rule 6. To obtain maximum sampling frequency the flow system should be designed to have minimum Sm and should be operated by injecting the smallest practical sample volume Sjj. FIA systems with minimum dispersion factor P1/2 will require the least volume of reagent solution and will yield maximum sampling frequency in relation to residence time of the zone continuously moving through the channel. 

The PSDs obtained from the ethane isotherms are shown in Fig. 3. The region of pore sizes studied by the ethane, from 6 to 20 A, can be divided into two main regions in this set of samples, above and below 13 A as the PSD evolves differently in these two regions. In the region of small pore sizes, the maximum is reached at the beginning of the reaction for the sample with 20 % bum-off, which also shifts to slightly smaller micropore sizes. As the reaction takes place, there is a continuous decrease in the pore volume related to the mean pore size. In the case of the region from 13 to 20 A the maximum is reached for the sample with 60% of bum-off and for a pore size of 17 A. 

This is a thermodynamic relation for ideal gases composed of non-interacting particles. R, the constant introduced to replace the product of Boltzmann s constant and Avogadro s number, is called the gas constant. Its value is 8.314472 J mol K . For a sample of gas particles free to move in some volume, the tendency to be in a state of maximum probability is related to the volume of the sample. 

Table 12-4 is a summary of liquid fuel speeifieations set by manufaeturers for effieient maehine operations. The water and sediment limit is set at 1% by maximum volume to prevent fouling of the fuel system and obstruetion of the fuel filters. Viseosity is limited to 20 eentistokes at the fuel nozzles to prevent elogging of the fuel lines. Also, it is advisable that the pour point be 20 °F (11 °C) below the minimum ambient temperature. Failure to meet this speeifieation ean be eorreeted by heating the fuel lines. Carbon residue should be less than 1% by weight based on 100% of the sample. The hydrogen eontent is related to the smoking tendeney of a fuel. Lower... 

To demonstrate the effect in more detail a series of experiments was carried out similar to that of volume overload, but in this case, the sample mass was increased in small increments. The retention distance of the front and the back of each peak was measured at the nominal points of inflection (0.6065 of the peak height) and the curves relating the retention data produced to the mass of sample added are shown in Figure 7. In Figure 7 the change in retention time with sample load is more obvious the maximum effect was to reduce the retention time of anthracene and the minimum effect was to the overloaded solute itself, benzene. Despite the reduction in retention time, the band width of anthracene is still little effected by the overloaded benzene. There is, however, a significant increase in the width of the naphthalene peak which... 

Fay and Lewis (1977) used spherical gas samples inside soap bubbles whose volumes ranged from 20 to 190 cm. Typically, a sphere was ignited with resistance wire, and the combustion process was then filmed with a high-speed camera. The fireball s maximum height and diameter, as well as the time needed to complete combustion, were evaluated. The fireball s thermal radiation was sensed by a radiation detector. Figure 6.3 relates fireball burning time and size to initial propane... 

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