Column supplier

Table 4.5 illustrates the chemical resistance of a series of columns materials across a range of organic solvents and chemical solutions. This list is not exhaustive and any detailed information regarding the column s compatibility to a particular solution should be provided by the column supplier. 

For proof of cleanabUity column suppliers need to provide data of how the equipment performs under bacterial challenge. An example of bacterial challenge is expressed in the next paragraph. 

Column 1 Suppose you want to use colunms from Waters, because Waters is your main column supplier. In this fictitious example, you have a completely unknown sample and for the overnight run using the column switch you would like to test quite different columns, so you need a variety of Waters columns. 

SEC column suppliers and dealers provide application data obtained from standard systems, using their columns, in their catalogues, so that one can know the capabilities of their columns. 

The authors are grateful to Mr. Hiroo Wada for his aid in the preparation of this chapter. The authors wish to thank the research groups of the SEC column suppliers and the dealers for their help in summarizing this chapter. 

To determine the elution (retention) volume Vr that corresponds to a certain molecular mass, the column must be calibrated with a standard mixture of known molar mass distribution. These standard, high-purity mixtures are available from various column suppliers. Remember that molecule size can change in different solvents and that different solutes (even with comparable molecular masses) can show differing molecular structure and size in the same solvent. In both cases, the retention volume obtained gives an incorrect molar mass. 

Analysis of specific components or classes of components in refinery gases can be accomplished with single-column analyses. However, combinations of columns and valving are required for more complete analyses. The various aspects of hydrocarbon gas analysis have been discussed by Thompson (61). Applicable columns for these applications can also be found in column supplier catalogs and the reviews by Mindrup (62) and Leibrand (63). 

If one observes difficulties with the reproducibility of a method, one should not, however, immediately blame the column manufacturer. If the method in question is a new method, i.e., a method that has not yet been used on many different columns, it is not impossible that the column-to-column differences observed are simply related to the age and use of these columns. Often, a brand new column wiU give different results compared to an old, much used column. In order to test this, it is worthwhile to check whether the two columns in question have been prepared from the same batch of packing material. This information may be contained in the Certificate of Analysis that came with the column, or it can be obtained from the manufacturer. If the batch of packing material in both columns is identical, the selectivity of the separation must be identical. If the selectivity is different, one can be sure that the differences are due to the age and use of the older column. This difficult situation is not the fault of the column manufacturer, and cannot be resolved by the column supplier. There is no other choice but to redevelop the separation from scratch. Unfortunately, many reproducibility problems are of this type. If, on the other hand, the new column is from a different batch of packing material than the older column, then one should inquire whether the manufacturer can supply a new column from the old batch of packing. This is usually possible, unless the old column really is several years old. 

The field of aqueous SEC is of growing interest and also represents an area of active development by several companies, with Polymer Laboratories included. In this area, contrary to the organic SEC scenario, a variety of polymer chemistries are employed in the preparation of the column packing materials. This fact alone makes the practice of aqueous SEC more difficult than its organic counterpart and requires the suppliers of such columns to offer a good level of technical support to the column user. This chapter outlines the characteristics and applications of PL aquagel-OH aqueous SEC columns. 

Because Dow is a global company and many different Dow sites would rely on these columns it was very important for the supplier to be able to guarantee column availability to all Dow locations. 

Polymer Laboratories was able to guarantee column supply by making up the gel in large batches and keeping packed columns in stock. This simple procedure has resulted in our never being without columns over the 10 years that they have been our supplier. 

For routine separations, there are about a dozen useful phases for capillary columns. The best general-purpose columns are the dimethylpolysiloxane (DB-1 or equivalent) and the 5% phenyl, 95% dimethylpolysiloxane (DB-5 or equivalent). These relatively nonpolar columns are recommended because they provide adequate resolution and are less prone to bleed than the more polar phases. If a DB-1, DB-5, or equivalent capillary column does not give the necessary resolution, try a more polar phase such as DB-23, CP-Sil88, or Carbowax 20M, providing the maximum operating temperature of the column is high enough for the sample of interest. See Appendix 3 for fused silica capillary columns from various suppliers. 

Ensure that the actual instrument configuration conforms to what is written under Experimental supplier, models, modifications, consumables (HPLC or GC columns, gaskets, etc.), and software for the main instrument, peripherals (injectors, integrators, computers, printers, plotters, etc.), and ancillary equipment (vortexer, dispensers, balances, centrifuges, filters, tubing, etc.). 

The 1000 A column did not show any resolution between 312 nm and 57 nm particle sizes. Shown in Fig.2 are the calibration curves for the 2000 A and 3000 A columns and for their combination. The 57 nm particle standard appears to have been erroneously characterized by the supplier. This was subsequently confirmed by electron microscopy. The 2000 X column exhibited a sharp upturn in its calibration curve close to the exclusion limit. It is to be noted that while data points corresponding to 312 and 275 nm diameter particles appear on individual column calibration curves, they are not indicated for the calibration curve of the combination. This is because these larger diameter particles were completely retained in the packed colimms, generating no detector response. The percentage recovery for these particles from individual columns was considerably less than 100 resulting in their complete retention when the columns were combined in series. 

Parameters that should be tested in HPLC method development are flow rate, column temperature, batch and supplier of the column, injection volume, mobile phase composition and buffer pH, and detection wavelength [2], For GC/GLC methods, one should investigate the effects of column temperature, mobile phase flow rate, and column lots or suppliers [38], For capillary electrophoresis, changes in temperature, buffer pH, ionic strength, buffer concentrations, detector wavelength, rinse times, and capillaries lots and supplier should be studied [35, 36], Typical variation such as extraction time, and stability of the analytical solution should be also evaluated [37],... 

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