Guard column cartridge

Because the instability of the N-oxide metabolite, which was subjected to decomposition during sample preparation (solvent evaporation during offline SPE), online SPE LC/MS became the method of choice for the application. Hsieh et al. (2004) built a system with two TFC cartridges and one analytical column, and another system with two TFC cartridges and two analytical columns for GLP quantitative bioanalysis of drug candidates. A Turbo C18 (50 x 1.0 mm, 5 /.mi, Cohesive Technologies), an Xterra MS C18 (30 x 2.0 mm, 2.5 /mi), and a guard column were used. Protein precipitation preceded injection. The cycle times for the two systems were 0.8 and 0.4 min. 

Bonded-phase silica and ion-exchange resins in plastic cartridges and mini-columns are very useful for off-line prepurification of samples, especially those for preparative chromatography, when appropriate pre- or guard columns may not be available for on-line clean-up of a sample. 

Aspirin and salicylic acid were eluted with a mobile phase of aqueous acetonitrile, acidified to pH 2.6, using orthophosphoric acid, at a flow rate of 1.5 ml/min. A UVA is detector was employed with a wavelength of 295 nm, 0.1 aufs sensitivity and a response time of 0.5sec. A 25 cm x 4 mm Lichrocart Cl 8 cartridge column with a guard column of the same material was used and the column temperature was maintained at 40 °C. 

Figure 3.6—HPLC column and guard column. Zorbax - column assembly and its exploded view. The removable precolumn (Guard cartridge) which is not expensive, prevents clogging of the analytical column while extending its lifetime and preserving its performance (reproduced by permission of RTI).

Orlando and Bonato [73] presented a practical and selective HPLC method for the separation and quantification of omeprazole enantiomers in human plasma. Ci8 solid-phase extraction cartridges were used to extract the enantiomers from plasma samples and the chiral separation was carried out on a Chiralpak AD column protected with a CN guard column, using ethanol-hexane (70 30) as the mobile phase, at a flow-rate of 0.5 ml/min. The detection was carried out at 302 nm. The method is linear in the range of 10-1000 ng/ml for each enantiomer, with a quantification limit of 5 ng/ml. Precision and accuracy, demonstrated by within-day and between-day assays, were lower than 10%. 

Plugged frit, pre-filter, guard column plugged inlet frit Backflush column/cartridge. Replace frit, pre-filter, guard column replace endfitting or frit assembly. 

Guard column 25x4 mm cartridge packed with LiChrospher 60 RP select B, 5 pm (Merck)... 

Guard column Taxsil guard cartridge (0335-CS) (MetaChem)... 

Fig. 11.3.1. HPLC separation of fatty acids. Chromatographic conditions column, Radial-Pak Cjg cartridge (5 jam) (100x8 mm I.D.) attached to a guard column (49x4.6 mm I.D.) dry packed with 37-SO /am C]g Corasil reversed phase material mobile phases, methanol-water-acetic acid (89 11 0.2) (A), methanol-water-acetic acid (80 20 0.2) (B) flow rates, 1.0 ml/min (A), 2.0 ml/min (B) detection, UV at 214 nm. Peaks 1, eicosapentaenoic acid (20 5, 2 aracUdonic acid (20 4,...

Measurements may be made directly with the extracts from filters, bulk collectors, particle collectors, solution bubblers, or diffusion tubes, or following concentration on solid cartridges or guard columns. Usually, air is first passed through the collected material and is then extracted into solutions for analysis. 

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