Application Of Breath Analysis Research Articles

Selective low concentration ammonia sensing in a microfluidic lab-on-a-chip

In the medical community, there is a considerable interest in a diagnostic breath analyzer for ammonia that is selectively enough to measure in exhaled air and small enough for the small volumes available in such an application. An indirect measurement system for low gaseous ammonia concentrations has been miniaturized and integrated on a chip in order to reach this goal. The detection limit of the system was calculated to be 1.1 parts per billion (ppb). The response time was determined to be 1.6 min with a gas How of 50 ml/min. The required gas volume for one measurement is therefore sufficiently small, although sampling assistance is required for breath analysis. The selectivity of the system is sufficient to measure ammonia concentrations in the low-ppb range. The system is even sufficiently selective to be used in environments that contain elevated carbon dioxide levels, like exhaled air. The lower ammonia concentration expected in diagnostic breath analysis applications, 50 ppb, was demonstrated to be detectable.

On-line monitoring of breath by membrane extraction with sorbent interface coupled with CO 2 sensor

In order to establish a simple and reproducible sampling device and method, which is crucial for a wide application of breath analysis, the original membrane extraction with sorbent interface (MESI) system was improved by coupling with a palm-size CO 2 sensor. Variations in analyte concentrations due to mass losses and different breathing patterns were normalized by simultaneously measuring the partial pressure of CO 2 and the concentrations of target analytes in the breath sampled. Analyte concentrations can then be expressed normalized to CO 2 as in the alveolar air. The MESI system was applied to study light hydrocarbons such as methane and ethane, which are difficult to analyse by other methods. A systematic study of breakthrough, which relates to the sorbent capacity and is characteristic of the analytical efficiency, was performed through the effects of analyte concentration, trap temperature, sample humidity and extraction time on breakthrough. Continuous on-line monitoring of breath methane and ethane was carried out under the optimum operation conditions based on the breakthrough study.

Clinical application of breath analysis for dimethyl sulfide following ingestion of dl-methionine

After overnight-fasting, the concentration of dimethyl sulfide in expired alveolar gas (alv-DMS) was determined serially following ingestion of 2 g of DL-methionine in normal subjects and patients with liver diseases. Alv-DMS rose to a peak in 30 to 90 min, declined markedly within 3 h, and then decreased gradually. Half-disappearance times ( T 1 2 ) (mean ± S.E. min) in each experimental group were: normal ( N = 9) 61.7 ± 4.7, acute hepatitis ( N = 6) 62.5 ± 6.8, chronic hepatitis ( N = 10) 84.0 ± 13.0, and liver cirrhosis ( N = 13) 159.2 ± 30.4, respectively. Cirrhotics had a T 1 2 significantly longer than that of the other three groups: vs. normal P < 0.02, vs. acute hepatitis P < 0.05, and vs. chronic hepatitis P < 0.05. T 1 2 of alv-DMS following ingestion of dl-methionine seems to be of clinical interest.