A Sensitive Isotope Selective Nondispersive Infrared Spectrometer for ¹³CO₂ and ¹²CO₂ Concentration Measurements in Breath Samples

Abstract

We present a nondispersive infrared spectrometer (NDIRS) for the measurement of the '3C0,/'2C0,-ratio in breath samples. A commercial NDIR spectrometer for CO, concentration measurements in industrial process control was modified using two separate optical channels for the 13C0, and "CO, detection. Cross interference due to overlapping absorption lines of both isotopic gases was successfully eliminated. The sensitivity of this device is & 0.4% of the '3C0,/'2C0,-ratio in a range of 2.5 to 5%of total CO,. This is sufficient for biomedical applications. Our spectrometer is small in size, cheap and simple to operateand thus a true alternative to isotope ratio mass spectrometers (IRMS). Several biomedical applications with breath samples were demonstrated and were compared in very good agreement with IRMS.

13C‐Methacetin metabolism in patients with cirrhosis: relation to disease severity, haemoglobin content and oxygen supply

“…The total amount of CO 2 and its 13 C/ 12 C ratio were analysed in each breath sample using isotope‐selective non‐dispersive infrared spectrometry (IRIS, Wagner Analysen Technik, Bremen, Germany). Exhaled peak 13 C dose per hour ( 13 C/h) and cumulative percentage 13 C dose recovered over 120 min (cumulative 13 C) were calculated according to a standard formula and expressed as percentage of total 13 C dose administered 4 …”

“…Exhaled peak 13 C dose per hour ( 13 C/h) and cumulative percentage 13 C dose recovered over 120 min (cumulative 13 C) were calculated according to a standard formula and expressed as percentage of total 13 C dose administered. 4 In 17 patients on day 1 transnasal oxygen inhalation (4 L/min) was started 15 min before methacetin administration and continued throughout the test procedure. On day 2 the methacetin breath test was repeated but no oxygen was administered.…”

Precision Trace Gas Analysis by FT-IR Spectroscopy. 2. The13C/12C Isotope Ratio of CO2

“…Recently isotope-selective nondispersive infrared (NDIR) spectrometers have been reported. − One such instrument has been designed primarily for analysis of CO 2 in exhaled breath for diagnostic purposes. For 500-mL breath samples, typically containing ∼4% CO 2 , δ 13 CO 2 is determined with a precision of ±0.4‰.…”

La spectroscopie infrarouge non dispersive : une alternative à la spectrométrie de masse isotopique. Cas du test respiratoire à l'urée 13C

“…En traversant la cellule, une partie de la lumière est absorbée, ceci provoque une augmentation de la température qui se traduit par une augmentation de la pression qui est détectée par le microphone condensateur. Pour chaque type de gaz à analyser, il faut une cellule remplie par le même gaz et un trajet optique diffé-rent [5].…”