Theophylline capillary

Hieda et al. determined theophylline, theobromine, and caffeine in human plasma and urine by gradient capillary HPLC with frit fast atom bombardment (FAB) mass spectrometry with 7-ethyl theophylline as the internal standard.64... 

L Steinmann, J Caslavska, W Thormann. Feasibility study of a drug immunoassay based on micellar electrokinetic capillary chromatography with laser-induced fluorescence detection—determination of theophyllin in serum. Electrophoresis 16 1912-1916, 1995. 

Chiem, N., Harrison, D.J., Microchip-based capillary electrophoresis for immunoassays analysis of monoclonal antibodies and theophylline. Anal. Chem. 1997, 69, 373-378. 

Q. Xun Dang, L. Xia Yan, Z.-Pei Sun, and D.-Kui Ling, Separation and simultaneous determination of the active ingredients in theophylline tablets by micellar electrokinetic capillary chromatography, J. Chromatogr., 630 363 (1993). 

An MECC immunoassay for serum theophylline was achieved on the cyclic CE microstructure, one to two orders of magnitude faster ( 30 sec) than the comparable separation using conventional fused silica capillaries, with higher efficiency and at no expense to accuracy or precision. The glass channels were not coated for these experiments, but they were rinsed with... 

Except for theophyllin, the solubilities are similar at a dissolution temperature (Td) and a dissolution pressure (Pd) of 65°C and 250bar, respectively, the mole fractions are of 2.5e-4 for anthracene, 5e-4 for caffeine and 6.5e-4 for salicylic acid. Theophyllin is an order of magnitude lower, with a value of 0.2e-4. The mole fractions allow one to estimate the maximum production rate for the experimental set up. Assuming a recovery of produced particles of 100%, and no dilution required for processing, the production rates are 1.0, 1.2, 0.5 and 0.04 g/h for caffeine, salicylic acid, anthracene and theophyllin, respectively (conditions Pd = 220bar, Td=65°C, capillary =1.5cm x 75pm flow rate of liquid C02=11.2ml/min)... 

Floberg et al. applied glass capillary gas chromatography for the analysis of theophylline and caffeine in plasma. The alkaloids were analyzed as such, or after derivatization. 

EP Lai, E Dabek-Zlotorynska. Separation of theophylline, caffeine and related drugs by normal-phase capillary electrochromatography. Electrophoresis 20 2366-2372, 1999. 

Cai LS, Wu CY, Mei SR, Zeng ZR (2004) Molecularly imprinted polymer theophylline retention and molecular recognition properties in capillary electrochromatography. Wuhan Univ J Natl Sci 9(3) 359-365... 

Epinephrine and isoproterenol (via cAMP mechanisms) and theophylline (via cAMP or block of adenosine receptors) inhibit the release of mediators from mast cells and basophils and cause bronchodilation. Diphenhydramine competitively blocks histamine actions at H, receptors, actions that would otherwise cause bronchoconstriction and increased capillary permeability. Dexamethasone has multiple cellular effects, including inhibition of IgE-producing clone proliferation, block of T helper cell function, and anti-inflammatory actions. Most of the actions of glucocorticoids result from decreases in the synthesis of cytokines (eg, interleukins, platelet activating factor) or eicosanoids (leukotrienes, prostaglandins). 

Illustrated in Figure 3 is a likely over-all mechanistic role of theophylline in asthma. Extrinsic or immediate hypersensitivity-type asthma begins with an antigen -antibody complex at mast cells and results in the release of chemical mediators which affect cells in airways. Smooth muscle cells contract, capillaries leak, and secretory cells hypersecrete to give a triad of bronchospasm, edema and Increased mucous, respectively. Shown is the two-enzyme... 

MEKC has been implemented in both microchip-based SCCE separations and capillary-based SCCE separations. Figure 24.21a shows a microchip-based SCCE separation using MEKC of FITC-labeled amino acids. The same chip was also used to resolve FITC-labeled components of human urine using MEKC in addition to performing an MEKC-based immunoassay of serum theophylline levels. MEKC using capillary-based SCCE has resulted in separations with as many as 100 million theoretical plates in 15 h of run time. A separation of L-phenylalanine and L-phenylalanine-ring-D5 is... 

Hieda, Y Kashimura, S. Hara, K. Kageura, M. [Development of the method for analysis of theophylline and its related compounds using capillary hi -performance liquid chromatography/fast atom bombardment-mass spectrometry]. Nippon Hoigaku Zasshi, 1994, 48, 253—262... 

Fig. 3 Hydrophilic interaction CEC separation of basic drugs spiked in human serum. Colunm fused-silica capillary, 27 cm (20 cm packed with 5 p.m, 300 A PolySULFOETHYL A particles). Mobile phase 80% v/v acetonitrile in 100 mM TEAP buffer. TEAP buffer at pH 2.8. Applied voltage 10 kV. Injection 0.5 psi for 90 sec. Temperature 25°C. Detection UV at 214 nm. Concentration of drugs 40 p,g/ml. Solutes 1, amo-barbital 2, phenobarbital 3, barbital 4, caffeine 5, sulfanilamide 6, theophylline 7, 2,4-dimethylquinoline 8, propranolol. Source From Determination of basic pharmaceuticals in human serum by hydrophilic interaction capilary electrochromatography, in Electrophoresis.

Fig. 4 Effect of the separation buffer type on stacking at a sample loading of 12% of the capillary volume. Top Borate buffer 210 mM, pH 8.6 bottom triethanolamine 160 mM, tricine 50 mM, pH 8.6 containing 10% acetonitrile. Separation of a mixture of weakly cationic and weakly anionic compounds in the same run doxepin (D, 50 mg/L), A -acetylprocainamide (N, 50 mg/L), quinine (Q, 20 mg/L), theophylline (T, 50 mg/L) and iothalamic acid (I, 20 mg/L) at 14 kV, 254 nm (M = Electro-osmotic flow).

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