Method development column testing during

Columns for a particular laboratory can be chosen based on some set of internal criteria. One of the criteria to select a column should be such that the column is stable for a certain number of column volumes (efficiency, tailing factor, and retention time criteria for predefined probe analytes) at the recommended maximum and minimum pH at a particular maximum temperature. This would allow the chromatographer to employ such phases with a significant degree of confidence and ensure the robustness of the stationary phase during method development and for release and stability testing. 

Some degradation products are either very polar or very nonpolar in nature this may present an issue in chromatography, where they may not be retained or strongly adsorbed on the column, respectively. One may also want to double check the reference standard for its purity, moisture content, and/or salt/ acid-base ratio for calculation. An analytical chemist must remember to explore all possibilities if mass balance issue is observed (either during method development, validation and/or stability testing). 

The exploratory practical work in the laboratory begins during method development after conclusion of the preliminary theoretical work on a separation problem. First, one specifies the possible influencing factors that are to be tested, e.g. six columns with different types of stationary phases, ideally with identical dimensions, the solvents acetonitrile and methanol, the column temperatures (15 °C and 45 °C), and if necessary, the influence of the pH (e.g., 2,7, and 9). Handbooks that have already been published on the strategic changes of chromatographic parameters can afford valuable assistance [3, 4] and should always be consulted to save time. 

PQ should be performed on a daily basis or whenever the instrument is used. The test frequency not only depends on the stability of the equipment but on everything in the system that may contribute to the results. For a liquid chromatograph, this may be the chromatographic column or a detector s lamp. The test criteria and frequency should be determined during the development and validation of the analytical method. 

A reversed-phase liquid chromatographic method was developed for simultaneous determination of carboxylic acids, phenolic compounds, and SA in white wines (84). The diluted samples are injected into a Spherisorb ODS-2 column with a gradient of sulphuric acid (pH 2.5)/methanol as mobile phase. A diode array detector is used, set at 210 nm for carboxylic acids and altered to 278 nm, during the run, for phenolics and SA. The identification of compounds is based on retention time and UV spectra. Some cleanup methods (Sep-Pak C18 and an ion-exchange column) were tested and did not improve the results. The analysis was considered simple, with no sample preparation. Application of this method was illustrated by analyses of Brazilian Welchriesling wines (84). 

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