A device for measuring human breath ammonia was developed based on a single use, disposable, inkjet printed ammonia sensor fabricated using polyaniline nanoparticles. The device was optimized for sampling ammonia in human breath samples by addressing issues such as variations in breath sample volume, flow rate, sources of oral ammonia, temperature and humidity. The resulting system was capable of measuring ammonia in breath from 40 to 2993 ppbv (r(2 )= 0.99, n = 3) as correlated with photoacoustic laser spectroscopy and correlation in normal human breath samples yielded a slope of 0.93 and a Pearson correlation coefficient of 0.9705 (p < 0.05, n = 11). Measurement of ammonia in the breath of patients with end-stage kidney disease demonstrated its significant reduction following dialysis, while also correlating well with blood urea nitrogen (BUN) (r = 0.61, p < 0.01, n = 96). Excellent intraindividual correlations were demonstrated between breath ammonia and BUN (0.86 to 0.96), which demonstrates the possibility of using low cost point of care breath ammonia systems as a noninvasive means of monitoring kidney dysfunction and treatment.

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Photoacoustic laser spectroscopy was used as a technique to measure real-time levels of ammonia in exhaled human breath in a small, locally recruited, normal healthy population (n = 30). This yielded an average level of breath ammonia of 265 ppb, ranging from 29 to 688 ppb. Although average levels were marginally higher in male volunteers, this was not statistically significant. In addition, no correlation could be found between age, body mass index, or breath carbon dioxide levels. Monitoring of the daily routine of two individuals showed a consistent decrease in oral breath ammonia concentrations by the early afternoon (post-prandial), but was followed by a gradual increase towards late afternoon. However, in a comparison of oral and nasal breath in two volunteers, nasal breath ammonia levels were found to be significantly lower than oral levels. In addition, the daily variation was only seen in oral rather than nasal measurements which may indicate that significant background levels are predominantly of oral origin and that nasal sampling is the preferred route to eradicate this background in future studies. These results provide a healthy human breath ammonia baseline upon which other studies may be compared.

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