Oxaliplatin represents a platinum-based cancerostatic drug that is widely used for the treatment of various types of cancer. There are two main platinum-containing impurities, impurity B and C, that can be formed as side products at very low concentrations. Their effect on biological systems can be like the oxaliplatin itself; however, this has not been fully investigated since there is a lack of methods for their determination in ultralow con-centrations. In our work, we present a method for ultra-trace determination of oxaliplatin impurities B and C, and oxaliplatin itself, using online sweeping preconcentration micellar electrokinetic chromatography coupled with inductively coupled plasma mass spectrometry (MEKC-ICP-MS). This is the first application of online pre-concentration with MEKC-ICP-MS to improve the detection limits of analytes. Under the optimal conditions, 25 mM sodium phosphate buffer at pH 2.15 with 175 mM SDS, and an injection time of 90 s at 50 mbar, baseline separation of all components within 6 min was achieved. The sweeping-MEKC-ICP-MS method was fully vali-dated in terms of linearity, limits of detection and quantification, trueness, precision, and reproducibility of migration times. Limits of detection of 2, 1, and 3 ng mL(-1) for impurity B, impurity C, and oxaliplatin, respectively, were obtained, which are 3,500-, 1,700-, and 2,100-fold lower than those for a MEKC-UV method also developed and validated as a part of this work. It also represents the detection of 98 femtograms of the impurity C (or 227 attomol of Pt) per injection. The sweeping-MEKC-ICP-MS method further benefits from a wide dynamic range up to six orders of magnitude (0.01-1,000 mu g mL(-1) for oxaliplatin) with coefficients of deter-mination greater than 0.9989. ICP-MS provides characteristic element/isotope-specific and structure-independent detection. ICP-MS helped identify the co-separated impurity B counter-ion that can be wrongly assigned as the platinum-based impurity B using standard UV detection. Finally, the validated sweeping-MEKC-ICP-MS method was applied to the analysis of oxaliplatin samples with variable impurities concentrations (0.06-1.0%). The trueness and precision ranged between 76 and 115% and 2-19%, respectively. This method allows the accurate determination of oxaliplatin impurities from 0.0003% levels; therefore, it could be used in routine pharmaceutical laboratories for quality control purposes.

The aim of our work was to develop a low-cost, portable device for the fast and easy determination of total protein content by using PDMS-based lab-in-a-syringe technology with removal of 3D-printed channels. We proposed two designs with a one-step PDMS curing and a two-step PDMS-curing fabrication procedure. The one-step PDMS microdevices were found to be the best in the view of preparation, repeatability, and stability of the reagent. This design was then applied for the determination of total protein content in biomedical products using the Bradford assay.

Introduction Capillary electrophoresis (CE) hyphenated to inductively coupled plasma mass spectrometry (ICPMS) as an element-specific detector represents an interesting and beneficial tool for many applications. Nowadays, CE-ICP-MS is used primarily for speciation analysis, metal-ligand interaction studies including metal-based nanoparticles, as recently reviewed [1]. However, CE-ICP-MS has the potential to touch also other fields by taking account of other advantages of CE, e.g. in chiral separations or in online preconcentration methodologies.

The aim of this study was to focus on the reduction of chiral selector concentration, sulfated-beta-cyclodextrin, in an attempt decrease the running costs associated with separating cetirizine enantiomers by capillary electrophoresis. The decrease in the concentration of chiral selector was achieved by adding D-glucose to the background electrolyte, which consisted of sodium borate. Optimal separation of cetirizine enantiomers was obtained in the electrolyte containing 500 mmol L-1 borate pH 9.5 with 1.0 mg mL(-1) sulfated-beta-cyclodextrin, and 1000 mmol L-1 D-glucose. This means a 15-fold reduction in the concentration of sulfated-beta-cyclodextrin. The mechanism of the separation in this electrolyte was investigated using direct injection mass spectrometry. The electrolyte of borate, D-glucose, and sulfated-beta-cyclodextrin forms a dual selector system, in which one selector is represented by the sulfated-beta-cyclodextrin and the second selector is represented by the D-glucose-borate complexes.

A novel simple isocratic HPLC method with UV detection for the determination of three compounds in spray solution (active component clotrimazole and two degradation products imidazole and (2-chlorophenyl)diphenylmethanol) using ibuprofen as an internal standard was developed and validated. The complications with different acido-basic properties of the analysed compounds in HPLC separation - while clotrimazole has pK(a) 4.7, imidazole has pK(a) 6.9 compared to relatively more acidic (2-chlorophenyl)diphenyl methanol - were finally overcome using a 3.5 mu m Zorbax (R) SB-Phenyl column (75 mm x 4.6 min i.d., Agilent Technologies).The optimal mobile phase for separation of clotrimazole, degradation products imidazole and (2-chlorophenyl)diphenylmethanol and ibuprofen as internal standard consists of a mixture of acetonitrile and water (65:35, v/v) with pH* conditioned by phosphoric acid to 3.5. At a flow rate of 0.5 ml min(-1) and detection at 210 nm, the total time of analysis was less than 6 min.The method was applied for routine analysis (batch analysis and stability tests) in commercial spray solution. (C) 2007 Elsevier B.V. All rights reserved.