Lichrosorb-DIOL column

Liquid chromatography cleanup on a LiChrosorb Diol column has been further proposed for the offline purification of chloramphenicol residues from bovine muscle and eggs (32). An online approach based on reversed-phase principles has also been described for isolation of chloramphenicol residues from swine kidney by an automated column switching system (63). Use of a protein exclusion column (Hisep) has been also suggested in an online trace-enrichment method for the determination of chloramphenicol in animal tissues (52). By employing a column-switching system, all chloramphenicol that eluted from the protein exclusion column was trapped at the entry of a 5 m Supelcosil LC-18 preconcentration column, to be subsequently back-flashed into the analytical column. 

Analytical and preparative separation of proteins soluble in an organic phase (n-propanol) has been carried out on a LiChrosorb-Diol column. This type of chromatography has been termed normal phase (R8). It has been applied to the analysis of proteins in dialyzed fetal calf serum (R8) and in the separation of protected hydrophobic oligopeptides (Nl), but as yet, it has not been used in a clinical chemical application. 

Fig. 16. Chromatogram of blank human serum calibrator-NADH mixture. Lichrosorb-DIOL column, flow rate 1.1 ml/min, detection by absorbance at 280 nm (A) HSA and IgG, (B) NADH, and (C) uric acid.

In this method the sample is applied to the column in a less polar solvent and eluted with a gradient of increasing polarity. Different species of human leukocyte interferon were separated on a Lichrosorb diol column with a gradient of decreasing n-propanol concentration (Rubinstein et a/., 1979). The Lichrosorb NH2 column has been used in the normal-phase mode for resolving amino acid mixtures (Schuster, 1980). 

Loodability studies on a LIChrosorb DIOL column of 6 mm and 23.4 mm bore and 250 mm length, packed with 5 fim material, yielded maximum sample capacities of 0.1 mg of protein per g of packing, in conjunction with a 20% loss In plate number. A sample containing variously 25 mg of albumin (bovine), chymotryp-sinogen and lysozyme was separated on a large—bore LIChrosorb DIOL column in 5 minutes with high resolution. 

As the phase ratio V /V and the slope D2 for the TSK gel SW 3000 column were the best of the columns tested, this column provided the highest resolution. However, the quality of the LiChrosorb DIOL column would appear to be heavily underestimated In this study due to its exceptionally low plate number. 

Guard column 15 x 4.6 7 ixm diol Column 200 x 4.6 5 p,m Lichrosorb diol Column temperature 25... 

Of course, UV or fluorescence detection is not suitable for determining PEG impurity in APE. Differential R1 detection is typical. In Zeman s general method for the analysis of ethoxylates on a LiChrosorb DIOL column, the system is optimized for separate... 

Figure 3. Plot of the log of the retention time vs. solvent strength measured with Nile Red for 5 phenols at 50° and 138 bar (outlet). The percent methanol in carbon dioxide is indicated at top of figure. Column 4.6 x 200 mm, 5 /im Lichrosorb Diol. Flow 2.5 ml/min.

Hyoscyamine can be determined by fluorimetric technique as follows (100). A solution of hyoscyamine or an eluate of it from a LiChrosorb DIOL HPLC column is treated with 9,10-dimethoxy anthracene-2-sulfonate solution. The resulting derivative is determined fluorimetrically at 446 nm with excitation at 383 nm. 

Column Lichrosorb Diol 10 pm (150x3.2 mm ID) loaded with 0.1 M naphtalene-2-sulfonate in 0.1 M aqueous phosphate buffer (pH 2.1) by subsequently pumping 30 ml of phosphate buffer (pH 2.1) and 50 ml of the stationary phase through the column, followed by the mobile phase until no more droplets could be observed in the eluate (ca. 20 ml). Finally the column was recycled with 500 ml of mobile phase. Mobile phase chloroform - n-propanol (9 1) and chloroform - n-propanol (9 1) saturated with the stationary phase mixecf in a ratio (1 9), flow rate 0.1> ml/min, detection UV 254 nm. Peaks 1, tetrabutylammonium 2, tributylmethylammonium 3, tetrapropylanmonium 4, tripropylmethylanmonium. (reproduced with permission from ref. 21, by the courtesy of Acta Pharmaceutica Suecica). 

For the separation of fullerenes by HPLC the stainless steel columns with Alusorb N 200, li Bondapak 10 CIS, LiChrosorb Diol, LiChrosorb SI 60 with bonded diphenylsilyl groups were used [16]. For the semi-preparative separation of Ceo and C70 glass column (70x12 mm) packed by LiChrosorb SI 60 with deposited carbon layer prepared by modified method [15] was used [16]. 

The most convenient column for the separation of fullerenes and their oxides is the column packed by LiChrosorb Diol with eluent containing n-hexane and n-pentane. This... 

It is important to select column switching times carefully in order to produce an effective sample cleanup. The selection was made by characterizing the Lichrosorb-DIOL precolumn and conducting a switching time survey. As a general guide to the column switching time selection procedure, we describe next in some detail the methods we used for this assay. The details of course will vary from system to system. 

Column 300 x 0.32 5 p-m LiChrosorb Diol Mobile phase Carbon dioxide MeOH 91.5 8.5 Column temperature 80 Iiljection volume 0.2 Detector UV 254... 

Fig. 11.2.3. HPLC of leucocyte interferon. Chromatographic conditions column, Lichrosorb Diol (250x4.6 mm I.D.) mobile phase, 80% n-propanol/0.1 N sodium acetate, pH 7.5, elution was achieved with a linear gradient of decreasing propanol concentration as shown flow rate, 0.25 ml/min temperature, ambient detection, post-column fluorescence using fluram. Reproduced from Rubinstein et al. (1980), with...

Figure 2.5 Supercritical fluid chromatogram, with use of a miniaturized evaporative lightscattering detector, of an extract obtained from oat bran. Column 100 nun x 0.9 mm, packed with LiChrosorb Diol, 5 pm. Conditions temperature 22°C pressure 300 atm. Mobile phase carbon dioxide modified with 19 mol% methanol. Restrictor 45 mm x 9 pm at 90°C. Peaks TG = triacylglycerols MGDG = monogalactosyldiacylglycerols PC = phosphatidylcholines DGDG = digalactosyldiacylglycerols.

The most extensive comparison of commercial SEC columns for water soluble polymers was carried out by Pfannkoch et al. The packings examined were TSK gel SW 3000 and 2000, SynChropak GPC 300 and 100, Waters 1-125, -Bondage I, Shodex OH-Pak B 804 and LiChrosorb DIOL. All columns exhibited pronounced ion exclusion characteristics for citric acid, which were, however, reduced by increasing the ionic strength. Hydrophobic effects were smailest... 

Figure 7.8 Comparison of the chromatographic behavior between Acclaim Mixed-Mode HILIC-1 and LiChrosorb Diol. Separator columns Acclaim Mixed-Mode HILIC-1,5 pm ( ) and LiChrosorb Diol, 5 pm ( ) column...

The HPLC system used for the separation of nonpolar lipid classes consisted of a Hewlett Packard (Avondale, PA, USA) Model 1050 ternary gradient system (HPLC pump, autosampler, and UV/visible detector), and an Alltech-Varex Mark HI ELSD (Alltech Associates, Deerfield, IL). The column was a LiChrosorb DIOL, 5 jiun, (3 x 100 mm from Chrompack, Inc., Raritan, NJ), and the flow rate was 0.5 ml/min. The solvents were A, hexane/acetic acid, 1000/1, v/v and B, hexane/isopropanol, 100/1, v/v, (Both were mixed fresh daily to eliminate variability caused by evaporation and/or absorption of moisture). The linear gradient timetable was At 0 min, 100/0 at 8 min, 100/0 at 10 min, 75/25 at 40 min, 75/25 at 41 min, 100/0 at 60 min, 100/0 (%A/%B, respectively). 

This method has been demonstrated for analysis of ethoxylates of alcohols, alkylphenols, fatty acids, sorbitan esters, glycerides, alkanolamides, and other materials. The HPLC method typically gives higher results than the extraction method. This procedure is readily adaptable to ordinary reversed-phase columns with methanol/water or acetonitrile/water mobile phases, provided that ordinary optimization procedures are followed. If desired, the molecular weight distribution of the PEG can be determined by HPLC analysis of the original sample on a LiChrosorb Diol (Merck) column, with isocratic mobile phase of 105 95 10 1 n-hexane/2-propanol/water/acetic acid and refractive index detection (25). An occasional back-flush of the column with the same mobile phase is required. 

---