Chromatography cellulose phases

Fig.4.38. Separation of carboxylic acids by ion-pair chromatography. Stationary phase N,N-dimethyl-protriptyline, 0.036 M, pH 9.0 (30% on cellulose). Mobile phase cyclohexane-chloroform-1-pentanol (15 4 1). Mobile phase speed 2 mm/sec. Column 300 X 2.7 mm I.D. Peaks B benzilic acid (0.7 nmole) P = phenylbutyric acid (1.1 nmoles) S = salicylic acid (1.4 nmoles).

In thin-layer chromatography cellulose can also be put in as a stationary phase Alumina and silica geP " and mfactures... 

Carbamates. Many examples of cellulose derivatives as chiral stationary phases (CSPs) in liquid chromatography and capillary electrophoresis have been reported in the literature [43,44]. Chankvetadze et al. [43] used cellulose chlorophenyl carbamates as liquid chromatography stationary phases to resolve enantiomers of several chiral drugs including sedatives... 

The competitive adsorption isotherms were determined experimentally for the separation of chiral epoxide enantiomers at 25 °C by the adsorption-desorption method [37]. A mass balance allows the knowledge of the concentration of each component retained in the particle, q, in equilibrium with the feed concentration, < In fact includes both the adsorbed phase concentration and the concentration in the fluid inside pores. This overall retained concentration is used to be consistent with the models presented for the SMB simulations based on homogeneous particles. The bed porosity was taken as = 0.4 since the total porosity was measured as Ej = 0.67 and the particle porosity of microcrystalline cellulose triacetate is p = 0.45 [38]. This procedure provides one point of the adsorption isotherm for each component (Cp q. The determination of the complete isotherm will require a set of experiments using different feed concentrations. To support the measured isotherms, a dynamic method of frontal chromatography is implemented based on the analysis of the response curves to a step change in feed concentration (adsorption) followed by the desorption of the column with pure eluent. It is well known that often the selectivity factor decreases with the increase of the concentration of chiral species and therefore the linear -i- Langmuir competitive isotherm was used ... 

Chapter 3 through Chapter 8 deal with the basic aspects of the practical uses of PLC. Chapter 3 describes sorbent materials and precoated layers for normal or straight phase (adsorption) chromatography (silica gel and aluminum oxide 60) and partition chromatography (silica gel, aluminum oxide 150, and cellulose), and precoated layers for reversed-phase chromatography (RP-18 or C-18). Properties of the bulk sorbents and precoated layers, a survey of commercial products, and examples of substance classes that can be separated are given. 

Hasegawa, M., Isogai, A., and Onabe, F., Size-exclusion chromatography of cellulose and chitin using lithium chloride-N,N-dimethylacetamide as a mobile phase, J. Chromatogr., 635, 334, 1993. 

Although the interest in, and application of layer chromatography has historically resulted from the development of PC, it was soon replaced by thin-layer chromatography (TLC). In PC, only one stationary phase matrix is available (cellulose), at variance to TLC (silica, polyamide, ion-exchange resins, cellulose). Using a silica-gel plate, separation of a sample can be accomplished in approximately 1 h as compared with many hours on paper. The plate size is much smaller than the necessary paper size. Also, more samples can be spotted... 

The TLC process is an off-line process. A number of samples are chromatographed simultaneously, side-by-side. HPTLC is fast (5 min), allows simultaneous separation and can be carried out with the same carrier materials as HPLC. Silica gel and chemically bonded silica gel sorbents are used predominantly in HPTLC other stationary phases are cellulose-based [393]. Separation mechanisms are either NPC (normal-phase chromatography), RPC (reversed-phase chromatography) or IEC (ion-exchange chromatography). RPC on hydrophobic layers is not as widely used in TLC as it is in column chromatography. The resolution capabilities of TLC using silica gel absorbent as compared to C S reversed-phase absorbent have been compared for 18 commercially available plasticisers, and 52 amine and 36 phenolic AOs [394]. 

This method was used, for example, for the solid-phase immunoassay of thyroxine (affinity chromatography). Various activation methods (CDI, periodate, and cyanogen bromide procedures) were compared with each other for coupling antibodies to magnetizable cellulose/iron oxide solid-phase particles. 211]... 

Ichihara, H., Fukushima, T., Imai, K. (1999).. Enantiomeric determination of d- and L-lactate in rat serum using high-performance liquid chromatography with a cellulose-type chiral stationary phase and fluorescence detection. Anal. Biochem. 269, 379-385. 

Tanaka, M., Yamazaki, H. (1996). Direct determination of pantoprazole enantiomers in human serum by reverse-phase high-performance liquid chromatography using a cellulose-based chiral stationary phase and column-switching system as a sample cleanup procedure. Anal. Chem. 68, 1513-16. 

In another study, the authors reported a comparative study of the enantiomeric resolution of miconazole and the other two chiral drugs by high performance liquid chromatography on various cellulose chiral columns in the normal phase mode [79], The chiral resolution of the three drugs on the columns containing different cellulose derivatives namely Chiralcel OD, OJ, OB, OK, OC, and OE in normal phase mode was described. The mobile phase used was hexane-isopropanol-diethylamine (425 74 1). The flow rates of the mobile phase used were 0.5, 1, and 1.5 mL/min. The values of the separation factor (a) of the resolved enantiomers of econazole, miconazole, and sulconazole on chiral phases were ranged from 1.07 to 2.5 while the values of resolution factors (Rs) varied from 0.17 to 3.9. The chiral recognition mechanisms between the analytes and the chiral selectors are discussed. 

In this study, Ali and Aboul-Enein [80] used cellulose tr is (3,5-d ich Ioropheny 1 carbamate) chiral stationary phase for the enantioseparation of miconazole and other clinically used drugs by high performance liquid chromatography. The mobile... 

Okamoto et al [85] performed the optical resolution of primaquine and other racemic drugs by high performance liquid chromatography using cellulose and amylose tris-(phenylcarbamate) derivatives as chiral stationary phases. Primaquine and other compounds were effectively resolved by cellulose and/or amylose derivatives having substituents such as methyl, tertiary butyl, or halogen, on the phenyl groups. 

Thin layer chromatography was carried out on 20x20cm glass plates coated 0.25mm thick with a suitable support and dried overnight. Silica gel G, silica gel H and cellulose were examined as the solid phases for chromatography of methanearsonate, arsenite and arsenate. Several sprays for the visualization of the arsenicals on plates were tested. Three of the more successful reagents and the colour produced with final product are shown in Table 13.2. 

Paper chromatography and thin-layer chromatography (TLC) constitute the planar methods mentioned above. Paper chromatography makes use of a sheet of paper having the consistency of filter paper (cellulose) for the stationary phase. Since such paper is hydrophilic, the stationary phase is actually a thin film of water unintentionally adsorbed on the surface of the paper. Thus, paper chromatography represents a form of partition chromatography only. The mobile phase is always a liquid. 

---