Determination of methyltin species in sediments using a pervaporation-gas chromatographic approach

Use of multiple headspace solid-phase microextraction and pervaporation for the determination of off-flavours in wine

The occurrence of off-flavours in wines and especially the so-called "cork taint defect" represents one of the most serious problem in wine industry in which 2,4,6-trichloroanisole has been blamed as the main responsible. The development of analytical methods for haloanisoles determination in wine/cork represent a challenge, mainly due to food matrix complexity and low taste and odour (T&O) threshold levels which are generally beyond the sensitivity of the analytical systems. In this work, a method based on the combined use of the recently developed multiple headspace solid-phase microextraction (MHS-SPME) and gas chromatography-ion-trap mass spectrometry has been optimised for the determination of haloanisoles in wines. This powerful analytical methodology is compared with several analytical approaches based on pervaporation, an innovative membrane-based technique similar to dynamic headspace. Analytical features of the methods assayed reveal their suitability for the appraisal of haloanisoles in this matrix in which threshold odor concentrations are in the range 4-40 ng l(-1). The analytical approaches have been applied to the analysis of haloanisoles in different Spanish white and red wines, in which spiking experiments showed good recoveries for the methodologies assayed.

Analysis of anisoles in wines using pervaporation coupled to gas chromatography–mass spectrometry

Two procedures for the determination of 2,4,6-trichloroanisole, 2,6-dichloroanisole and 2,4,6-tribromoanisole in tainted wines have been developed. Both methods are based on pervaporation (PV) of the analytes and final determination by gas chromatography-ion-trap tandem mass spectrometry (GC-MS). In the Approach A, pervaporation was directly coupled to the GC-MS system (PV-GC-MS/MS) and in Approach B a solid-phase cryogenic trap-thermal desorption (CT-TD) device was connected to the pervaporator (PV-CT-TD-GC-MS/MS). Results show that last coupling present better sensitivity as well as precision. Detection limits (DLs) for 2,4,6-trichloroanisole were estimated to be 25.8 and 4.2 ng l(-1) for Approaches A and B, respectively, when 10 ml of sample was analysed. Linear range of the calibration curves ranged from quantification limit to 15 ng for PV-GC-MS/MS and from quantification limit to 2 ng for PV-CT-TD-GC-MS/MS. Due to the low threshold odour concentration of these compounds in wine, Approach B is proposed as a reliable method for analytical quality control of this product.

Determination of flavour and off-flavour compounds in orange juice by on-line coupling of a pervaporation unit to gas chromatography–mass spectrometry

A method for the analysis of several volatiles compounds responsible for orange juice flavour (ethyl butanoate, limonene, linalool, alpha-pinene, geranial, neral and alpha-terpineol) has been developed. The isolation of this compounds was carried out by pervaporation (PV) followed by on-line gas chromatography-mass spectrometry (GC-MS). The coupling PV-GC-MS has been successfully applied to fresh hand-squeezed orange juices and frozen concentrated ones in order to establish differences in their flavour profile. Method has been validated with recovery spike experiments which showed its applicability for a wide range of concentrations.