We used a high-resolution mid-IR tunable-laser absorption spectroscopy (TLAS) system with a single IV-VI laser operating near 5.2 microm to measure the level of exhaled nitric oxide (eNO) in human breath. A method of internal calibration using simultaneous eNO and exhaled CO2 measurements eliminated the need for system calibration with gas standards. The results observed from internally calibrating the instrument for eNO measurements were compared with measurements of eNO calibrated to gas standards and were found to be similar. Various parameters of the TLAS system for eNO breath testing were examined and include gas cell pressure, exhalation time, and ambient NO concentrations. A reduction in eNO from elevated concentrations (approximately 44 parts in 10(9)) to near-normal levels (<20 parts in 10(9)) from an asthmatic patient was observed after the patient had received treatment with an inhaled glucocorticoid anti-inflammatory medication. Such measurements can help in evaluating airway inflammation and in monitoring the effectiveness of anti-inflammatory therapies.

Although breath analysis was successfully implemented in a research feedlot, arrival rumen temperature, eN(2)O, eCO, and haptoglobin concentration were not accurate in predicting occurrence of BRD during a preconditioning program. However, these biomarkers might support the diagnosis of BRD.

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A tunable diode laser absorption spectroscopy (TDLAS) system equipped with a IV-VI mid-IR laser operating near 5.2>mu;m was used to measure exhaled nitric oxide (eNO) and carbon dioxide (CO(2)) simultaneously in human breath over a single exhalation. Breath was sampled in real time, and eNO levels were measured from seven volunteers, two steroid-naive asthmatics and five nonasthmatics. Measured CO(2) levels were used as an internal standard to verify correct breath collection and calculate eNO values. Calculated eNO concentrations agreed well with reported values for asthmatic and nonasthmatic individuals.

A high-resolution liquid-nitrogen-free mid-infrared tunable diode laser absorption spectroscopy (TDLAS) system was used to perform real-time measurement of acetaldehyde concentrations in human exhaled breath following ingestion of an alcoholic beverage. Acetaldehyde absorption features were measured near 5.79 mum (1727 cm(-1)) using a IV-VI semiconductor laser, a 100 m long path optical gas cell, and second- harmonic detection coupled with wavelength modulation. Acetaldehyde levels were measured with a minimum detection limit of 80 ppb for 5 s integration time. The variations in exhaled acetaldehyde levels over time were analyzed prior to and following ingestion of two different amounts of white wine. A method to calibrate acetaldehyde measurements internally using water vapor absorption lines was investigated to eliminate the need for system calibration with gas standards. The potential of a TDLAS system to be used as a noninvasive clinical tool for measurements of large volatile compounds with possible applications in cancer detection is demonstrated.