Estimation of chromatographic parameters on two silica-based columns connected in series under nonaqueous reversed phase liquid chromatographic conditions.

Empirical equations were produced to relate important chromatographic parameters on two silica-based columns serially linked, in isocratic nonaqueous RP HPLC, to retention times and peak widths of the separated compounds on the individual columns. These equations were derived because the experimental data seemed to deviate from the values expected, applying basic chromatographic theoretical equations. The chromatographic parameters studied were retention time, peak width, resolution, number of theoretical plates, capacity factor, and separation factor.

C(18) columns for the simultaneous determination of oxytetracycline and its related substances by reversed-phase high performance liquid chromatography and UV detection.

Simultaneous determination of oxytetracycline, 4-epioxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline on C(18) columns has been accomplished using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS RP-C(18) column (250 mm x 4.6 mm) and on a Waters C(18) Symmetry column (150 mm x 3.

Development and validation of a non-aqueous reversed-phase high-performance liquid chromatographic method for the determination of four chemical UV filters in suncare formulations.

A non-aqueous reversed-phase high performance liquid chromatographic method (RP-HPLC) with UV detection at 313 nm was developed and validated for simultaneous determination of methylene bis-benzotriazolyl tetramethylphenol (Tinosorb M) along with three other chemical UV filters, octocrylene (Eusolex OCR), octyl methoxycinnamate (Eusolex 2292) and octyl salicylate (Eusolex OS) in suncare products. An isocratic elution was performed on a Hypersil BDS RP-C18 column (250 mm x 4.6 mm), 5 microm particle size, using a mobile phase consisted of methanol-acetonitrile (90:10, v/v) with a flow-rate of 1.