title: An infrared spectroscopy method to detect ammonia in gastric juice.
abstract: Ammonia in gastric juice is considered a potential biomarker for Helicobacter pylori infection and as a factor contributing to gastric mucosal injury. High ammonia concentrations are also found in patients with chronic renal failure, peptic ulcer disease, and chronic gastritis. Rapid and specific methods for ammonia detection are urgently required by the medical community. Here we present a method to detect ammonia directly in gastric juice based on Fourier transform infrared spectroscopy. The ammonia dissolved in biological liquid samples as ammonium ion was released in air as a gas by the shifting of the pH equilibrium of the ammonium/ammonia reaction and was detected in line by a Fourier transform infrared spectroscopy system equipped with a gas cell for the quantification. The method developed provided high sensitivity and selectivity in ammonia detection both in pure standard solutions and in a simulated gastric juice matrix over the range of diagnostic concentrations tested. Preliminary analyses were also performed on real gastric juice samples from patients with gastric mucosal injury and with symptoms of H. pylori infection, and the results were in agreement with the clinicopathology information. The whole analysis, performed in less than 10 min, can be directly applied on the sample without extraction procedures and it ensures high specificity of detection because of the ammonia fingerprint absorption bands in the infrared spectrum. This method could be easily used with endoscopy instrumentation to provide information in real time and would enable the endoscopist to improve and integrate gastroscopic examinations.
authors.affiliation: Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135, Turin, Italy. a.giovannozzi@inrim.it.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Giovannozzi
authors.affiliation: Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135, Turin, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pennecchi
authors.affiliation: NISO Biomed S.r.l., Via Ippolito Nievo 25, 10153, Turin, Italy.
authors.forename: Paul
authors.initials: P
authors.lastname: Muller
authors.affiliation: NISO Biomed S.r.l., Via Ippolito Nievo 25, 10153, Turin, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Balma Tivola
authors.affiliation: NISO Biomed S.r.l., Via Ippolito Nievo 25, 10153, Turin, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Roncari
authors.affiliation: Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135, Turin, Italy.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Rossi
mesh_terms: D000641:Ammonia / Q000032:analysis*; D000643:Ammonium Chloride / Q000032:analysis; D002138:Calibration; D016022:Case-Control Studies; D002446:Celiac Disease / Q000378:metabolism / Q000473:pathology; D002849:Chromatography, Gas / Q000295:instrumentation; D005750:Gastric Juice / Q000737:chemistry*; D005773:Gastroscopy; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori / Q000378:metabolism / Q000472:pathogenicity; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012015:Reference Standards; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation / Q000379:methods*; D013276:Stomach Ulcer / Q000175:diagnosis* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology
chemical_list: D000643:Ammonium Chloride; D000641:Ammonia
keywords: Ammonia; Fourier transform infrared spectroscopy; Gastric juice; Gastric mucosal injury; Helicobacter pylori