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A method for the determination of volatile organic compounds (VOCs) at sub-trace levels in breath samples based on a multibed sorption trap for the collection and concentration of VOCs, a comprehensive multidimensional gas chromatograph (GCxGC) for the separation of complex mixtures, and a time-of-flight mass spectrometer detector is designed and developed. The good performance of the trap tube device developed for the concentration together with the high sensitivity and separation power of the GCxGC results in a powerful system. In the analysis of samples, more than 100 different compounds are detected of which between 65 and 85 are clearly identified. A total of approximately 250 different compounds are observed in all the samples evaluated of which 142 are identified. A preliminary study to evaluate breath biomarkers for active smoking is performed. The levels of previously described biomarkers are found to be strongly time-dependent with amounts found approximately 1 h after smoking returning to the levels found in nonsmoking volunteers. However, 2,5-dimethylfuran, 2-methylfuran, and furan are found to be effective biomarkers given that they were only found in samples taken from smokers and could still be detected more than 2 h after smoking.

Thermal infrared (TIR) data are usually acquired at 1 a coarser spatial resolution (CR) than visible and near infrared 2 (VNIR). Several disaggregation methods have been recently devel-3 oped to enhance the TIR spatial resolution using VNIR data. These 4 approaches are based on the retrieval of a relation between TIR 5 and VNIR data at CR, or training of a neural network, to be 6 applied at the fine resolution afterward. In this work, different 7 disaggregation methods are applied to the combination of two 8 different sensors in the experimental test site of Barrax, Spain. 9 The main objective is to test the feasibility of these techniques 10 when applied to satellites provided with no TIR bands. Landsat 11 and moderate imaging spectroradiometer (MODIS) images were 12 used for this work. Land surface temperature (LST) from MODIS 13 images was disaggregated to the Landsat spatial resolution using 14 Landsat VNIR data. Landsat LST was used for the validation 15 and comparison of the different techniques. Best results were 16 obtained by the method based on a linear regression between 17 normalized difference vegetation index (NDVI) and LST. An aver-18 age RMSE = ±1.9 K was observed between disaggregated and 19 Landsat LST from four different dates in a study area of 120 km 2. 20 Index Terms-Image enhancement, image resolution, remote 21 sensing, temperature. 22 I. INTRODUCTION 23 T IME series of fine spatial and temporal resolution images 24 are key inputs in numerous studies, e.g., water resources 25 management [1], [2]. However, there is a limitation in the exist-26 ing satellites since revisit time for fine spatial resolution sensors 27 is typically poor, while those with a high revisit frequency are 28 characterized by a coarse spatial resolution. This is especially 29 true when focusing on the thermal infrared (TIR) since spa-30 tial resolution for the TIR bands is always coarser than that for 31 the visible and near infrared (VNIR) bands onboard the same 32 sensor [2]. 33 Disaggregation methods allow downscaling the TIR coarse 34 resolution (CR) to finer resolutions. In [3], a review of land 35 Manuscript

The combination of a tandem column ensemble and an on-line microsorption trap is used for the analysis of organic compounds in human breath samples. The four-bed sorption trap uses a series of discreet sorption beds containing three grades of graphitized carbon and a carbon molecular sieve to quantitatively remove most organic compounds from 0.8-L breath samples. The trap is then heated to 300 degrees C in approximately 1.5 s and maintained at this temperature for 10 s. The resulting vapor plug width is in the range 0.7-1.3 s for the compounds found in the breath samples. The separation is performed with a 15-m-long, 0.25-mm-i.d. capillary using a 0.5-microm-thick film of nonpolar dimethyl polysiloxane coupled in series to a polar column, either trifluoropropylmethyl polysiloxane or poly(ethylene glycol). Both column combinations are successful in separating the early-eluting compounds acetone, isoprene, pentane, methyl alcohol, and ethyl alcohol, which are all common in breath samples. The poly(ethylene glycol) combination gave better separation but showed relatively fast deterioration for repeated analysis of wet samples. Breath samples were obtained under different conditions (smoker, nonsmoker, gum chewer), and 25 compounds were identified in the various samples. Many additional peaks are observed but not identified. Analytical curves (log-log) of peak area versus sample volume for test compounds are linear in the range 80-800 cm3. Detection limits (3sigma) for several volatile compounds in 800-cm3 samples are in the 1-5 ppb range.

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