Infrared Carbon Dioxide Analyzer Research Articles

Determination of photochemically produced carbon dioxide in seawater

An analytical system was developed to determine photochemically produced carbon dioxide in marine waters. Our system was designed to measure low levels of carbon dioxide by maintaining a closed system to prevent atmospheric contamination during sample preparation, irradiation, and analysis. To detect low levels of photoproduced carbon dioxide in seawater, background dissolved inorganic carbon (DIC) was removed before irradiation. To strip out DIC, samples were acidified to pH 3.0 (converting DIC to carbon dioxide) and bubbled with low carbon dioxide air. The pH was then readjusted back to the original value, and the resulting low‐DIC seawater samples were transferred pneumatically to air‐tight quartz tubes for irradiation. During analysis, samples were pneumatically transferred to a sample loop, injected, and acidified. Carbon dioxide was then stripped out, dried, and carried to a nondispersive infrared carbon dioxide analyzer. Calibration was done with a series of low concentration aqueous carbonate standards (0.05 to 3 µmol L−1). The detection limit, defined as the concentration corresponding to three times the standard deviation of the experimental blank (i.e., DIC‐stripped seawater), was ~60 nmol L−1. Method precision was largely dependent on the agreement between multiple injections from the same tube (< ±2% relative standard deviation [RSD]) and the reproducibility between different tubes (±3% RSD). This method was used to measure carbon dioxide photoproduction in a variety of waters (e.g., estuarine, lake) including the first direct measurements in marine waters.

Accuracy and reliability of the self-inflating bulb to verify tracheal intubation in out-of-hospital cardiac arrest patients.

To determine the sensitivity and specificity of the self-inflating bulb (SIB) to verify tracheal intubation in out-of-hospital cardiac arrest patients. Sixty-five consecutive adult patients with out-of-hospital cardiac arrest were enrolled. Patients were provided chest compression and ventilation by either ba-valve-mask or the esophageal tracheal double-lumen airway by ambulance crews when they arrived at the authors' department. Immediately after intubation in the emergency department, the endotracheal tube position was tested by the SIB and end-tidal carbon dioxide (ETCO2) monitor using an infrared carbon dioxide analyzer. We observed the SIB reinflating for 10 s, and full reinflation within 4 s was defined as a positive result (tracheal intubation). Five esophageal intubations occurred, and the SIB correctly identified all esophageal intubations. Of the 65 tracheal intubations, the SIB correctly identified 47 tubes placed in the trachea (72.3%). Delayed but full reinflation occurred in one tracheal intubation during the 10-s observation period. Fifteen tracheal intubations had incomplete reinflation during the observation period, and two tracheal intubations did not achieve any reinflation. Thirty-nine tracheal intubations were identified by ETCO2 (60%). When the SIB test is combined with the ETCO2 detection, 59 tracheal intubations were identified with a 90.8% sensitivity. The authors found a high incidence of false-negative results of the SIB in out-of-hospital cardiac arrest patients. Because no single test for verifying endotracheal tube position is reliable, all available modalities should be tested and used in conjunction with proper clinical judgment to verify tracheal intubation in cases of out-of-hospital cardiac arrest.

End-tidal carbon dioxide concentration, carbon dioxide production, heart rate, and blood pressure as indicators of induced hyperthermia

In 4 spontaneously breathing, barbiturate-anesthetized dogs, hyperthermia was induced with 2,4-dinitrophenol while rectal temperature, heart rate, mean blood pressure, end-tidal carbon dioxide, and carbon dioxide production (milliliters per minute) were measured continuously. The latter was determined with a pneumotachygraph (to obtain respired volume) and an infrared carbon dioxide analyzer that measured inspired and expired carbon dioxide concentration. Of the five physiologic measurements, the increase in carbon dioxide production preceded the increase in rectal temperature by more than 120 seconds. End-tidal carbon dioxide was an unreliable indicator in the spontaneously breathing animal of approaching hyperthermia during spontaneous breathing due to a transient tachypnea, which decreased end-tidal carbon dioxide. The carbon dioxide production (milliliters per minute) increased immediately and reached three to five times the control value. Blood pressure and heart rate were insensitive indicators of approaching hyperthermia.

Oxygen and Carbon Dioxide Fluxes from Barley Shoots Depend on Nitrate Assimilation

A custom oxygen analyzer in conjunction with an infrared carbon dioxide analyzer and humidity sensors permitted simultaneous measurements of oxygen, carbon dioxide, and water vapor fluxes from the shoots of intact barley plants (Hordeum vulgare L. cv Steptoe). The oxygen analyzer is based on a calciazirconium sensor and can resolve concentration differences to within 2 microliters per liter against the normal background of 210,000 microliters per liter. In wild-type plants receiving ammonium as their sole nitrogen source or in nitrate reductase-deficient mutants, photosynthetic and respiratory fluxes of oxygen equaled those of carbon dioxide. By contrast, wild-type plants exposed to nitrate had unequal oxygen and carbon dioxide fluxes: oxygen evolution at high light exceeded carbon dioxide consumption by 26% and carbon dioxide evolution in the dark exceeded oxygen consumption by 25%. These results indicate that a substantial portion of photosynthetic electron transport or respiration generates reductant for nitrate assimilation rather than for carbon fixation or mitochondrial electron transport.

ESTIMATION OF ARTERIAL PCO2 DURING HIGH FREQUENCY JET VENTILATION: Studies in the Dog

The arterial to end-tidal PCO2 difference (PaCO2-PE'CO2) was measured in five anaesthetized dogs during controlled ventilation at 0.25 Hz (15 b.p.m.) and during high frequency jet ventilation at 1, 3 and 5 Hz. Because of the slow response of the infra-red carbon dioxide analyser, satisfactory recordings of end-tidal carbon dioxide could not be obtained at frequencies greater than 1 Hz. The interruption of high frequency jet ventilation by conventional ventilation resulted in approximately equal arterial and end-tidal PCO2 values during the first breath, and restoration of the normal arterial to end-tidal PCO2 difference by the third breath. It is concluded that, when high frequency jet ventilation at 1, 3 or 5 Hz is interrupted with normal tidal volumes at low frequencies, the arterial PCO2 can be estimated from recordings of the end-tidal PCO2.

ASSESSMENT OF THE HEWLETT-PACKARD HP47210A CAPNOMETER

The Hewlett-Packard HP47210A Capnometer, a "mainstream" infra-red carbon dioxide analyser, has a sensor in-line with the patient circuit. The calibration apparatus is included within the unit, and an internal microprocessor corrects for the presence of nitrous oxide and varying concentrations of oxygen. Maximum error was 0.37 kPa for carbon dioxide partial pressures less than 5.3 kPa, and less than 3.6% for partial pressures of carbon dioxide greater than 5.3 kPa.

Application of thermal analysis to the characterization of organic aerosol particles

A number of Los Angeles aerosol samples, collected on quartz filters, were analyzed by thermal (effluent gas) analysis. The method involves heating the sample at a predetermined termperature rate in oxygen. The evolved gases are passed over a copper oxide catalyst to assure their complete conversion to carbon dioxide, which is detected by a nondispersive infrared carbon dioxide analyzer. The output of the analysis is a thermogram, i.e., a CO 2 versus temperature plot. The thermograms of ambient samples show distinctive peaks that correspond to the volatilization, decomposition and combustion of different carbonaceous materials, such as volatile organics, higher molecular weight organic species, elemental carbon, and carbonates. The features of the thermograms are distinctly different for aged aerosols than for fresh source-dominated particles. Also, at the receptor site there are substantial differences between daytime and nighttime samples. Based on these results, aided by results on solvent treated samples, an empirical approach to differentiate primary and secondary organics will be described.

The effect of nitrous oxide on an infrared carbon dioxide analyser.

The effect of nitrous oxide on an infrared carbon dioxide analyser.

Measurement of alveolar carbon dioxide tension at maximal expiration as an estimate of arterial carbon dioxide tension in patients with airway obstruction.

Arterial and alveolar carbon dioxide tension at end-tidal and maximal expiration were measured simultaneously in 104 patients with chronic obstructive respiratory disease. Regardless of the degree of abnormality of distribution of ventilation, there was a consistent relationship between arterial and maximal expiratory carbon dioxide tension. Therefore, close approximation of arterial carbon dioxide tension was obtained from the measurement of carbon dioxide tension at maximal expiration by rapid infrared carbon dioxide analysis. An infrared carbon dioxide analyzer might be used at the bedside or in the laboratory for frequent monitoring of arterial carbon dioxide tension without repeated arterial punctures.

Photosynthesis, Respiration and Post‐illumination Fixation of CO2 by Corn Leaves as Influenced by Light and Oxygen Concentration

AbstractThe effect of oxygen concentration on the rate of CO2‐uptake in continuous and intermittent light was studied as well as the CO2‐fixation during a short dark period after light was turned off. In addition the dark respiration and the CO2‐compensation point of attached and detached corn leaves were determined. Leaves of 4 to 22‐day old plants were used as experimental material. A closed circuit system of an infrared carbon dioxide analyzer was employed to measure the rate of CO2‐exchange. It was found that in an atmosphere consisting of 100 % oxygen, there was about 50 per cent inhibition of the rate of CO2‐uptake in continuous and intermittent light compared to that in an atmosphere consisting of 21% oxygen. The same was true of the rate of CO2‐fixation in darkness during a short period after the light was turned off. Since the response to oxygen concentration of the CO2‐uptake in light and of the CO2‐fixation in darkness after the light was turned off were similar, it is concluded that the fixation of CO2 in the short dark period represents an over‐ shoot of photosynthesis. The rate of dark respiration was little affected by the oxygen concentration in the ranges used in the experiments. The carbon dioxide compensation point which has been observed in leaves of 4 to 14‐day old plants was not influenced by either oxygen concentration or light intensity. Since the changes in the rate of CO2‐uptake due to changes in the concentration of oxygen and light intensity had no effect on the CO2‐compensation point, it is concluded that a reabsorption of respiratory CO2 by photosynthesis could not account for the low value of this point. These results are interpreted as a further corroboration of the statement that the leaves of corn lack the process of photorespiration and that dark respiration is inhibited in light.It was observed that the rate of the CO2‐uptake gradually increased in plants which were from 4 to 22‐days old. The inhibitory effect of high concentration of oxygen on the rate of CO2‐uptake was relatively higher in old plants than in young ones.

Effect of Temperature, CO2 Concentration, and Light Intensity on Oxygen Inhibition of Photosynthesis in Wheat Leaves

The effect of 21% O(2) and 3% O(2) on the CO(2) exchange of detached wheat leaves was measured in a closed system with an infrared carbon dioxide analyzer. Temperature was varied between 2 degrees and 43 degrees , CO(2) concentration between 0.000% and 0.050% and light intensity between 40 ft-c and 1000 ft-c. In most conditions, the apparent rate of photosynthesis was inhibited in 21% O(2) compared to 3% O(2). The degree of inhibition increased with increasing temperature and decreasing CO(2) concentration. Light intensity did not alter the effect of O(2) except at light intensities or CO(2) concentrations near the compensation point. At high CO(2) concentrations and low temperature, O(2) inhibition of apparent photosynthesis was absent. At 3% O(2), wheat resembled tropical grasses in possessing a high rate of photosynthesis, a temperature optimum for photosynthesis above 30 degrees , and a CO(2) compensation point of less than 0.0005% CO(2). The effect of O(2) on apparent photosynthesis could be ascribed to a combination of stimulation of CO(2) production during photosynthesis, and inhibition of photosynthesis itself.

Photosynthesis, Photorespiration and Respiration of Detached Spruce Twigs as Influenced by Oxygen Concentration and Light Intensity

AbstractThe effects of oxygen concentration and light intensity on the rates of apparent photosynthesis, true photosynthesis, photorespiration and dark respiration of detached spruce twigs were determined by means of an infra‐red carbon dioxide analyzer (IRCA). A closed circuit system IRCA was filled with either 1 per cent of oxygen in nitrogen, air (21 % O2) or pure oxygen (100 % O2). Two light intensities 30 × 103 erg · cm −2· s−1 and 120 × 103 erg · cm−2· s−1 were applied.It has been found that the inhibitory effect of high concentration of oxygen on the apparent photosynthesis was mainly a result of a stimulation of the rate of CO2 production in light (photorespiration). In the atmosphere of 100 % O2, photorespiration accounts for 66–80 per cent of total CO2 uptake (true photosynthesis). Owing to a strong acceleration of photorespiration by high oxygen concentrations, the rate of true photosynthesis calculated as the sum of apparent photosynthesis and photorespiration was by several times less inhibited by oxygen than the rate of apparent photosynthesis. The rates of dark respiration were essentially unaffected by the oxygen concentrations used in the experiments. An increase in the intensity of light from 30 × 103 erg · cm−3· s−1 to 120 · 103 erg · cm−2· s−1 enhanced the rate of photorespiration in the atmospheres of 21 and 100 % oxygen but not in 1 % O2. The rate of apparent photosynthesis, however, was little affected by light intensity in an atmosphere of 1 % oxygen.

Measurement of inorganic carbon and photosynthesis in seawater by pCO2 and pH analysis

An infrared carbon dioxide analyzer was used to measure the pCO2 of air in equilibrium with seawater. From the pCO2 and pH of the seawater, the amount of bicarbonate plus carbonate ion could be calculated. These values were also obtained by acidifying the seawater and measuring the amount of carbon dioxide that was released. These methods provide accurate measurements of the concentrations of inorganic carbon which are available for photosynthesis by marine plants. For example, these techniques showed that Iridaea cordatum used bicarbonate ion rather than CO2 during photosynthesis at high pH.

Apparent Reassimilation of Respiratory Carbon Dioxide by Different Plant Species

AbstractDifferences among species in respiration rates in CO2‐free air, in light and dark, were studied using the standard leaf chamber technique and the infrared carbon dioxide analyzer. Photosynthesis, transpiration and respiration were measured. In all species studied, rates of respiration were considerably higher in dark than in light. This effect was assumed to be due to reassimilation of the respiratory CO2. A resistance analogy model was derived to account for the apparent differences in internal recycling of CO2 among species; the differences were correlated with differences in maximum photosynthetic rates in normal air and optimal conditions (P310) and with internal resistances to CO2 diffusion (rk). Species with high P310 and low rk appear to reassimilate all the endogenous CO2, whereas other species with lower P310 and higher rk appear to reassimilate only a part of their respiratory CO2.Experiments with the photosynthetic inhibitor, 3‐(3,4‐dichlorophcnyl)‐l,l‐dimethyl urea (DCMU), indicated that species with zero respiration in CO2‐free air and light release respiratory CO2 when photosynthesis is inhibited. It is concluded that the CO2 released in the presence of DCMU represents respiratory CO2 which recycles to photosynthesis under normal conditions.

FURTHER EVIDENCE ON THE EFFECTS OF LIGHT ON RESPIRATION DURING PHOTOSYNTHESIS

Chlorophyll-rich and chlorophyll-deficient leaves of soybean, peperomia, and corn were compared for the effects of previous illumination on the rate of carbon dioxide evolution in the subsequent dark period. An infrared carbon dioxide analyzer was used to measure these rates. It was found that the initial rate of carbon dioxide production in the dark was affected by previous illumination in proportion to the capacity of the leaves for photosynthesis. Light accelerated carbon dioxide production in green soybean and perperomia leaves, but inhibited it in green corn leaves.Using a Geiger tube to follow changes in the concentration of C14O2 around detached tobacco leaves, it was concluded that some recent product of photosynthesis was the substrate for the initial postillumination production of carbon dioxide. All above results indicated that there was a close relationship between the photosynthetic apparatus of the leaves and the production of carbon dioxide both during and immediately following a period of illumination.

Prolonged hyperventilation in man. Associated electrolyte changes and subjective symptoms.

There are a number of reports concerning the physiological effects of voluntary hyperventilation in the human.^1-7Hyperventilation has been said to be an extremely fatiguing activity. Accordingly, most of the previous studies on voluntary hyperventilators have been for relatively short periods of time. The purpose of this report is to point out our observations in 4 volunteers who hyperventilated for periods up to 4 hours and longer. Observations were made regarding (1) subjective symptoms and (2) changes in electrolytes. The fall of serum inorganic phosphorus concentration was so marked in our cases that we felt justified in reemphasizing this observation. <h3>Procedure</h3> By means of the Beckman Spinco infrared carbon dioxide analyzer, the alveolar CO₂was monitored via an intranasal catheter and maintained in the range of 2.0% to 2.5% (or approximately one-half the normal level for these subjects). The rate and amplitude of respiration were constantly adjusted to