Identification and semi-quantitative analysis of parabens and UV filters in cosmetic products by direct-analysis-in-real-time mass spectrometry and gas chromatography with mass spectrometric detection.

A method based on direct-analysis-in-real-time mass spectrometry (DART-MS) for the qualitative and semi-quantitative analysis of eight organic UV filters and four parabens in twelve cosmetic products with substantially different formulations (as cream, milk, lotion, oil, lipstick) was developed. All tested substances could be identified unambiguously in the investigated samples without any sample pre-treatment. Direct analysis of cosmetic products allows semi-quantitative determination of parabens.

A remarkable cyclization of TADDOL-bisthioacetate under oxidative conditions.

Attempted oxidation of a TADDOL-derived bisthioacetate resulted in a rather unexpected and remarkable cyclization and deprotection reaction, giving a thiolane-1, 1-dioxide as the main product. Systematic in situ ESI-HRMS studies revealed a bicyclic, highly acid labile key intermediate of this reaction. Supported by force field calculations, the high sensitivity of this intermediate was judged to be due to the formation of a highly strained -configured bicyclo[3.

Investigations on the migration behavior of insulin and related synthetic analogues in CZE, MEKC and MEEKC employing different surfactants.

The retention/migration behavior of insulin and five synthetic insulin analogues in CZE, MEKC and MEEKC employing seven different detergents within the latter two techniques has been investigated. Substantial changes in separation selectivity in MEKC could be observed for several insulins when moving from SDS to cholate-based micellar systems. Customized separations could be achieved by using mixtures of SDS and deoxycholate.

Determination of organic UV filters in water by stir bar sorptive extraction and direct analysis in real-time mass spectrometry.

A screening method for analyzing environmental waters contaminated with UV filters using direct analysis in real-time mass spectrometry (DART-MS) was developed. To demonstrate the suitability of DART-MS a test set of seven organic UV filters, namely benzophenone-3 (BP-3), ethylhexyl dimethyl p-aminobenzoate (OD-PABA), 4-t-butyl-4'-methoxydibenzoylmethane (BM-DBM), homomethyl salicylate (HMS), 2-(ethylhexyl) salicylate (EHS), octocrylene (OC), and 4-methylbenzylidene camphor (4-MBC), was defined. In the first step, standard solutions of the analytes prepared in methanol were investigated in order to determine optimum parameters for the DART-MS.

Rapid identification of stabilisers in polypropylene using time-of-flight mass spectrometry and DART as ion source.

A method for analysing plastic samples without any sample pretreatment using direct analysis in real time mass spectrometry (DART-MS) was developed. DART-MS allows the direct, simple and rapid identification of polymer additives in plastic products. To demonstrate the suitability of DART-MS for the detection of a wide range of commonly employed stabilising agents, a test set of 21 stabilisers was selected.

Analysis of melamine in milk powder by CZE using UV detection and hyphenation with ESI quadrupole/TOF MS detection.

An easy to employ method for the determination of melamine in milk powder samples using CZE with either UV or MS detection is presented. The separation capabilities of CZE allowed keeping sample preparation rather simple. Before analysis, milk powder samples were dissolved in water, de-fatted with dichloromethane and diluted with ACN to precipitate the protein, filtrated and injected without further pretreatment.

Investigations on the migration behaviour of purines and pyrimidines in capillary electromigration techniques with UV detection and mass spectrometric detection.

Different approaches for the separation of a set of nucleosides and nucleobases using capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) are described. Several electrolyte compositions have been tested for this purpose. The addition of appropriate amounts of borate to the carrier electrolyte allowed manipulating migration orders in CZE and MEKC by selective complexation of the nucleosides.

Improved analysis of melamine-formaldehyde resins by capillary zone electrophoresis-mass spectrometry using ion-trap and quadrupole-time-of-flight mass spectrometers.

An improved method based on capillary zone electrophoresis (CZE) coupled to either ion-trap (IT) mass spectrometry (MS) or quadrupole-time-of-flight (Q-TOF) MS for the analysis of melamine-formaldehyde condensates is presented. Employing a formic acid-based electrolyte containing 50% acetonitrile (ACN) and MS detection up to 13 compounds could be determined in lab-made resins, synthesized by mixing formaldehyde and melamine in different ratios ranging from 1:1.5 to 1:4.

Microemulsion electrokinetic chromatography with on-line atmospheric pressure photoionization-mass spectrometric detection of medium polarity compounds.

In this paper, we present the determination of pharmaceuticals employing microemulsion electrokinetic chromatography (MEEKC) with atmospheric pressure photoionization-mass spectrometric (APPI-MS) detection. This recent hyphenated technique allows to overcome some disadvantages of MEEKC, namely its inherent incompatibility with MS detection. Important parameters like microemulsion (ME) composition, the composition of the sheath liquid and APPI-MS detection parameters have been investigated.

Microemulsion electrokinetic chromatography with on-line atmospheric pressure photoionization mass spectrometric detection.

In the present paper we report, for the first time, the successful on-line coupling of microemulsion electrokinetic chromatography (MEEKC) with mass spectrometric (MS) detection using an atmospheric pressure photoionization interface. Microemulsions (MEs) including mostly volatile ingredients and classical MEs based on nonvolatile buffer components and sodium dodecyl sulfate (SDS) as surfactant were compared with respect to their compatibility with MS detection. The investigations performed revealed that MEs with up to 3% SDS and buffers containing sodium borate can be employed without significant suppression of the MS signals.