Metal-organic frameworks for the sorption of acetone and isopropanol in exhaled breath of diabetics prior to quantitation by gas chromatography.

A method is described for non-invasive glucose monitoring of diabetics by means of breath analysis. The metal-organic frameworks (MOFs) ZIF-7, UiO-66 and MOF-5 were chosen as sorbents in packed tubes for sampling and preconcentration of acetone and isopropanol which are established diabetes biomarkers. The MOF UiO-66 was found to be the most appropriate sorbent. Following thermal desorption, acetone and isopropanol where quantified by GC. The method has low limits of detection (0.79-0.84 µg·L-1) and wide linear ranges (5-2000 µg·L-1). It is assumed that the good performance of UiO-66 as a sorbent results from its large surface area and unique porous structure, and from van der Waals interactions. The relative standard deviation for six replicate cycles of sampling and preconcentration using one 50 mg UiO-66 packed tube ranged between 2.3 and 6.7% for intra-day assays, and from 2.7 to 4.3% for inter-day assays. A tube packed with 50 mg of UiO-66 packed tube can be used in over 120 cycles of adsorption/desorption without significant loss of collection efficiency. The GC method has been applied for the analysis of diabetic breath samples, and the recoveries from spiked samples ranged from 89.1 to 107.6%. Graphical abstract Schematic presentation of metal-organic frameworks as sorbents combined with thermal desorption-gas chromatography for the determination of acetone and isopropanol in exhaled breath of diabetics.

A gate-opening controlled metal-organic framework for selective solid-phase microextraction of aldehydes from exhaled breath of lung cancer patients.

A stainless steel fiber was coated with a gate-opening controlled metal-organic framework ZIF-7 via a sol-gel method and applied to the solid-phase microextraction of aldehydes (hexanal, heptanal, octanal, nonanal, decanal) from exhaled breath by lung cancer patients. The effects of temperature and time on the sorption and desorption were optimized. Under optimum condition, the modified fiber displays enrichment factors (typically ranging from 300 to 10,000), low limits of detection (0.61-0.84 µg L-1), and wide linear ranges of hexanal, heptanal (5-500 µg L-1) and octanal, nonanal, decanal (10-1000 µg L-1). The high extraction capability for aldehydes is thought to result from (a) the combined effects of the large surface area and the unique porous structure of the ZIF-7, (b) the hydrophobicity and gate-opening effect of the sorbent, (c) the high selectivity of the window, and (d) the presence of unsaturated metal-coordination sites. The coated fiber is thermally stable and can be re-used >150 times. The relative standard deviation (RSD) for six replicate extractions using a single fiber ranged from 1.4-15.3% for intra-day and 2.4-16.1% for inter-day. The fiber-to-fiber reproducibility for three fibers prepared in parallel was in the range of 2.4-12.6% (RSD). The method was applied to the extraction of aldehydes from real samples and to the quantitation by gas chromatography. Recoveries from spiked samples ranged from 84 to 113%. Graphical abstract A metal-organic framework ZIF-7 coated stainless steel fiber was prepared via sol-gel method. The self-made fiber was applied in the solid phase microextraction of aldehydes from exhaled breath of lung cancer patients.