Comparison of 624-type Capillary Columns II

"Equivalent Columns" Deviation in the Quantitative Analysis

Abstract

The present paper is the continuation of our "equivalent column" study. 624-type columns were investigated in a capillary gas chromatograph with a flame ionization detector (FID). In the preceding work, we used a homemade test mixture containing mainly acidic type compounds, which we complemented in the current study with additional basic test compounds to give a more precise description of the behaviour of the stationary phases. The columns had the same dimensions (30 m × 0.32 mm × 1.0 μm; length, internal diameter and film thickness, respectively) but were purchased from different manufacturers or the same manufacturer but from different batches. In addition, also their pre-life was different. These circumstances influence the condition of the stationary phase, and therefore their separation ability. These factors imply the necessity of testing the column from time to time. To distinguish between the separation ability of the columns, we compared the chromatograms, the retention times and retention order of the molecules, as well as peak asymmetry factors. Besides these parameters, quantitative determination is also performed based on the results of separation. We used the effective carbon number (ECN) and the limit of quantitation (LoQ) to demonstrate these differences which are caused by the different stationary phase conditions.