Fast and Accurate Exhaled Breath Ammonia Measurement

Solga, Steven F.; Mudalel, Matthew L.; Spacek, Lisa A.; Risby, Terence H.

doi:10.3791/51658

Cited by 14 publications

(11 citation statements)

References 15 publications

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“…In order to mimic exhaled breath, we prepared simulated breath composed of 76.3% nitrogen, 15.2% oxygen, 4% carbon dioxide, 3.1% water vapor, 0.83% argon, and small amounts of neon and helium by mixing air with carbon dioxide using an MFC. This composition is close to that of typical exhaled breath 48 . For ammonia-sensing measurements, the prepared exhaled air was first injected into the chamber, the baseline was checked, and an NH 3 stream at the desired concentration was introduced.…”

Section: Methodssupporting

confidence: 79%

Highly sensitive ammonia sensor for diagnostic purpose using reduced graphene oxide and conductive polymer

Park

2018

Sci Rep

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In this study, we fabricate ammonia sensors based on hybrid thin films of reduced graphene oxide (RGO) and conducting polymers using the Langmuir-Schaefer (LS) technique. The RGO is first prepared using hydrazine (Hy) and/or pyrrole (Py) as the reducing agents, and the resulting pyrrole-reduced RGO (Py-RGO) is then hybridized with polyaniline (PANI) and/or polypyrrole (PPy) by in-situ polymerization. The four different thin films of Hy-RGO, Py-RGO, Py-RGO/PANI, and Py-RGO/PPy are deposited on interdigitated microelectrodes by the LS techniques, and their structures are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results of ammonia sensing experiments indicate that the Py-RGO/PANI film exhibits the highest sensor response of these four films, and that it exhibits high reproducibility, high linearity of concentration dependency, and a very low detection limit (0.2 ppm) both in N2 and exhaled air environments. The current gas sensor, therefore, has potential for diagnostic purposes because it has the additional advantages of facile fabrication, ease of use at room temperature, and portability compared to conventional high-sensitivity ammonia sensors.

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Section: Methodssupporting

confidence: 79%

Highly sensitive ammonia sensor for diagnostic purpose using reduced graphene oxide and conductive polymer

Park

2018

Sci Rep

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“…Each breath was sampled continuously via a 50 cm long inlet line (Teflon) heated to 55 °C and the concentration of ammonia was determined with quartz enhanced photoacoustic spectrometry [7] as previously described [8, 14]. Plateau breath ammonia concentrations measured during the phase III portion of the exhalation profile were reported in parts per billion (ppb).…”

Section: Methodsmentioning

confidence: 99%

Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults

et al. 2015

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Blood ammonia is routinely used in clinical settings to assess systemic ammonia in hepatic encephalopathy and urea cycle disorders. Despite its drawbacks, blood measurement is often used as a comparator in breath studies because it is a standard clinical test. We sought to evaluate sources of measurement error and potential clinical utility of breath ammonia compared to blood ammonia. We measured breath ammonia in real time by quartz enhanced photoacoustic spectrometry and blood ammonia in 10 healthy and 10 cirrhotic participants. Each participant contributed 5 breath samples and blood for ammonia measurement within 1 h. We calculated the coefficient of variation (CV) for 5 breath ammonia values, reported medians of healthy and cirrhotic participants, and used scatterplots to display breath and blood ammonia. For healthy participants, mean age was 22 years (±4), 70% were men, and body mass index (BMI) was 27 (±5). For cirrhotic participants, mean age was 61 years (±8), 60% were men, and BMI was 31 (±7). Median blood ammonia for healthy participants was within normal range, 10 μmol L−1 (interquartile range (IQR), 3–18) versus 46 μmol L−1 (IQR, 23–66) for cirrhotic participants. Median breath ammonia was 379 pmol mL−1 CO2 (IQR, 265–765) for healthy versus 350 pmol mL−1 CO2 (IQR, 180–1013) for cirrhotic participants. CV was 17 ± 6%. There remains an important unmet need in the evaluation of systemic ammonia, and breath measurement continues to demonstrate promise to fulfill this need. Given the many differences between breath and blood ammonia measurement, we examined biological explanations for our findings in healthy and cirrhotic participants. We conclude that based upon these preliminary data breath may offer clinically important information this is not provided by blood ammonia.

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“…It is a colorless, irritating odor and highly toxic gas, therefore, the detection of ammonia is very important due to the potential threat to people’s health posed by ammonia [ 1 , 2 ]. Meanwhile, since ammonia is a byproduct of protein metabolism, the detection of ammonia can help clinicians assess diseases and state of health [ 3 , 4 ]. Due to the merits of non-invasion, quickness, convenience, and repeatability, exhaled ammonia detection has attracted more attention for early diagnosis of many diseases such as hepatic injury, kidney diseases, Helicobacter pylori infection and halitosis [ 5 , 6 , 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

A Reduced GO-Graphene Hybrid Gas Sensor for Ultra-Low Concentration Ammonia Detection

Wang

Lei

et al. 2018

Sensors

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A hybrid structure gas sensor of reduced graphene oxide (RGO) decorated graphene (RGO-Gr) is designed for ultra-low concentration ammonia detection. The resistance value of the RGO-Gr hybrid is the indicator of the ammonia concentration and controlled by effective charge transport from RGO to graphene after ammonia molecule adsorption. In this hybrid material, RGO is the adsorbing layer to catch ammonia molecules and graphene is the conductive layer to effectively enhance charge/electron transport. Compared to a RGO gas sensor, the signal-to-noise ratio (SNR) of the RGO-Gr is increased from 22 to 1008. Meanwhile, the response of the RGO-Gr gas sensor is better than that of either a pristine graphene or RGO gas sensor. It is found that the RGO reduction time is related to the content of functional groups that directly reflect on the gas sensing properties of the sensor. The RGO-Gr gas sensor with 10 min reduction time has the best gas sensing properties in this type of sensor. The highest sensitivity is 2.88% towards 0.5 ppm, and the ammonia gas detection limit is calculated to be 36 ppb.

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Fast and Accurate Exhaled Breath Ammonia Measurement

Cited by 14 publications

References 15 publications

Highly sensitive ammonia sensor for diagnostic purpose using reduced graphene oxide and conductive polymer

Highly sensitive ammonia sensor for diagnostic purpose using reduced graphene oxide and conductive polymer

Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults

A Reduced GO-Graphene Hybrid Gas Sensor for Ultra-Low Concentration Ammonia Detection

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