Direct temperature-controlled trapping system and its use for the gas chromatographic determination of organic vapor released from human skin

Real time monitoring of generation and decomposition of degradation products in lithium oxygen batteries during discharge/charge cycles by an online cold trap pre-concentrator-gas chromatography/mass spectroscopy system

Degradation products of lithium oxygen batteries with a tetraethylene glycol dimethyl ether (TEGDME) electrolyte solution during discharge/charge cycles were monitored by an online cold trap pre-concentrator-gas chromatography/mass spectroscopy system in real time. A total of 37 peaks were detected and 27 of them were assigned to specific molecules. Degradation compounds were generated and decomposed in very complex manners during discharge/charge cycles. Most molecules were generated during charge as a result of the degradation of TEGDME by active oxygen species and/or electrochemical oxidation. These molecules generated during charge were decomposed during discharge by active oxygen species.

Skin ethanol gas measurement system with a biochemical gas sensor and gas concentrator toward monitoring of blood volatile compounds

We developed a biochemical gas sensor (bio-sniffer) using the enzymatic reaction of alcohol dehydrogenase (ADH) to target ethanol in skin gas. By introducing a gas concentrator using liquid nitrogen, we constructed a highly sensitive system for skin gas measurements. The ethanol bio-sniffer was built from an optical-fiber probe employing an ADH enzyme membrane, an UV-LED light source for excitation, and a photomultiplier tube. Ethanol was measured by detecting the autofluorescence of the coenzyme NADH due to the enzymatic reaction of ADH. We established a system for measuring concentrated gases by connecting the sensor with a gas concentrator and introducing concentrated skin gas to the sensing surface. This suppressed diffusion of the concentrated gases to achieve maximum fluorescence intensity by optimizing the measurement system. The calibration curve from obtained peak values showed ethanol gas can be measured over 1-3100 ppb, which included skin gas concentrations during alcohol consumption. Finally, when applied to measurements of ethanol in skin gas following alcohol consumption, the output was found to be dependent on concentration, similarly to using standard gases. Consecutive measurements were possible using periodic sampling with 6-min intervals for 180 min of monitoring. Skin ethanol concentrations rose from 20 min after consuming the alcohol, exhibited a peak value of 25 ppb skin gas ethanol at around 60 min, and gradually declined. Thus, the system can be used for non-invasive percutaneous evaluation of human volatile organic chemicals in blood.

Transcutaneous Blood VOC Imaging System (Skin-Gas Cam) with Real-Time Bio-Fluorometric Device on Rounded Skin Surface

A skin-gas cam that allows continuous imaging of transcutaneous blood volatile organic compounds (VOCs) emanated from human skin was developed. The skin-gas cam is able to reveal the relationship between the local skin conditions and transcutaneous blood VOCs in the field of volatile metabolomics (volatolomics). A ring-type ultraviolet (UV) light-emitting diode was mounted around a camera lens as an excitation light source, which enabled the simultaneous excitation and imaging of fluorescence. A nicotinamide adenine dinucleotide (NAD)-dependent alcohol dehydrogenase (ADH) was used to detect ethanol as a model sample. When gaseous ethanol was applied to an ADH-immobilized mesh that was wetted with an oxidized NAD solution placed in front of the camera, a reduced form of NAD (NADH) was produced through an ADH-mediated reaction. NADH emits fluorescence by UV excitation, and thus, the concentration distribution of ethanol was visualized by measuring the distribution of the fluorescence light intensity from NADH on the ADH-immobilized mesh surface. In this study, a new gas application method that mimicked the release mechanism of transcutaneous gas for quantification of the transcutaneous gas concentration was evaluated. Also, spatiotemporal changes of transcutaneous ethanol for various body parts were measured. As a result, we revealed a relationship between local skin conditions and VOCs that could not be observed previously. In particular, we demonstrated the facile measurement of transdermal gases from around the ear where capillaries are densely distributed below a thin stratum corneum.

Development of a new measurement system to detect selectively volatile organic compounds derived from the human body

A new concept expired gas measurement system used double cold-trap method was developed. The system could detect selectively volatile organic compound (VOC) derived from the human body. The gas chromatography (GC) profiles of healthy volunteer's expired gas collected by our system were analyzed. As a result, 60 VOCs were detected from the healthy volunteer's expired gas. We examined 14 VOCs among them further, which could be converted to the concentration from the GC profiles. The concentration of almost VOCs decreased when the subjects inspired purified air compared with the atmosphere. On the other hand, isoprene was almost the same. It was strongly suggested that these VOCs were derived from the human body because the concentration of these VOCs in the atmosphere were nearly zero. Expired gas of two sleep apnea syndrome (SAS) patients were analyzed as preliminary study. As a result of the study, the concentration of some VOCs contained in the expired gas of the SAS patients showed higher value than a healthy controls.

Acetone concentration in gas emanating from tails of diabetic rats

This study investigated the effects of diabetic rats induced by streptozotocin (STZ) on acetone concentration emanating from the tail of a rat. Experiments were carried out with male Wistar rats (9 weeks of age, 220 - 250 g body weight). Glucose concentration in the blood was 10.8 ± 0.7 mmol/l for the control group and 39.6 ± 2.4 mmol/l for the diabetic group. β-Hydroxybutyrate concentration in blood was 218 ± 52 µmol/l for the control group and 1439 ± 101 µmol/l for the diabetic group. Both glucose and β-hydroxybutyrate concentrations in the blood of the diabetic group were significantly higher than those of the control group (p < 0.001). Skin gas acetone concentration emanated from rat tail was 124 ± 46 ppb for control and 1134 ± 417 ppb for diabetic. Skin gas acetone concentration emitted from the tail of a rat with diabetes was significantly higher than that from a rat in the control group (p < 0.001). The result indicates that skin acetone emanating from a rat tail is a useful parameter to use for insulin-dependent diabetes (type I).

Relationship between skin acetone and blood beta-hydroxybutyrate concentrations in diabetes

BACKGROUND

Acetone is emitted from the skin and acetone concentrations correlate with blood beta-hydroxybutyrate.

METHODS

Skin acetone concentrations of 63 patients with diabetes and 32 control subjects were measured by cold trapping followed by gas chromatography.

RESULTS

Skin acetone concentrations of patients with diabetes (188+/-17 ppb; mean+/-SE) were significantly higher than those of the control subjects (87+/-10 ppb, p<0.01). There was no significant difference in skin acetone concentrations among patients with diabetes with regard to mode of treatment. Skin acetone concentrations were correlated with blood beta-hydroxybutyrate (r=0.669, p<0.01), blood glucose (r=0.608, p<0.01), and HbA1c (r=0.292, p<0.05) in patients with diabetes. Skin acetone concentration was high (940 ppb) in a patient with diabetic ketoacidosis, and it fell to 80 ppb after insulin therapy.

CONCLUSION

Measurement of skin acetone can be used as a screening test for ketoacidosis provided the analytical methods and tools become simpler. Moreover, it could become a marker of diabetic control and of ketone production in diabetes and other ketogenic conditions.

Identification of Ammonia in Gas Emanated from Human Skin and Its Correlation with That in Blood

Identifying and measuring the ammonia gas that emanates from human skin, which we called skin gas, has been achieved using a modified gas chromatographic system with a nitrogen-selective detector (flame-thermoionic detector: FTD). The skin gas is collected with a home-made sampling probe or bag, which is used to cover the skin surface of a subject's wrist, or a finger, for 5 min. It was proved that ammonia was present in skin gas for healthy persons and patients with hepatic disease. The average amounts of ammonia were 1.7 +/- 0.4 and 2.7 +/- 0.8 ng/cm2; furthermore, there was a significant difference between them (p < 0.05). In addition, the ammonia levels present in skin gas were correlated with that in blood (r = 0.64, p < 0.05).

Preparation of a New Type of Fiber Adsorbent Attached with Silica Microparticles

A new type of fiber adsorbent attached with silica microparticles was prepared. The silica microparticles were formed by the polymerization of silica oligomers on glass fibers, which were woven into a glass filter. The surface of the silica microparticles was chemically modified by bonding C18-ligands. SEM images indicated that the diameter of the uniform and spherical silica microparticles fixed on glass fibers was on the order of micrometers. It was confirmed that the glass filter adsorbent was effective for the adsorptive removal of toluene of low concentrations.

Exhalation behavior of four organic substrates and water absorbed by human skin

The simultaneous measurement of several volatile organic compounds and water released from the human skin can be achieved successfully by using a modified gas chromatographic system. After the thumb of each subject was dipped in aqueous solution containing acetone, diethyl ether, ethanol, and toluene, it was dried in the air. Then the thumb attached to the sampling probe for measuring the released gases. It is found that 90% of all these chemical substrates were desorbed after 20 min. The initial exhalation rate factor for each chemical substrate was determined in every subject. Correlation factors of the linear relationships between the initial exhalation rate for hydrophilic substrates (acetone and ethanol) and the total amount of water (TAW) released from the skin were 0.94 and 0.92, respectively. However, the rate of hydrophobic toluene was not dependent on the TAW. Therefore, the exhalation rate of substrates is greatly influenced by both their hydrophilicity and TAW. Additionally, an interesting personal specific character among the 6 subjects was observed on plotting the exhalation rate of organic substrates and water during the elapsed time. With the released water mostly due to insensible perspiration, the exhalation rate of all simultaneous organic substrates decreased monotonically over the elapsed time. On the contrary, when subjects sweated emotionally, the exhalation rate of organic substrates showed some variation, namely a higher of exhalation rate compared to the case of mostly due to insensible perspiration. Therefore, emotionally-induced sweating can enhance the release of organic substrates.