Characteristic negative response of the helium ionization detector

Andrawes, Fikry F.; Gibson, E. K.

doi:10.1021/ac50056a018

Cited by 21 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bartlett et al (37) have described an electrochemical cell for detection of Hz which correlated well with results obtained by conventional GC/thermal conductivity devices. The more sensitive helium ionization detector has also been utilized in breath Hz analysis (28); however, the operational shortcomings of this device have been well documented (38,39) . A more recent analytical technique utilizing gas chromatography and a reduction gas detector has also been described (30,40) .…”

Section: Methodsmentioning

confidence: 99%

Breath Hydrogen Analysis

Ostrander,

Cohen,

Hopper

et al. 1983

J. pediatr. gastroenterol. nutr.

View full text Add to dashboard Cite

Summary:Hydrogen gas (H2) is a product of the fermentation of dietary carbohydrate (CHO) by bacteria in the lumen of the gastrointestinal tract in man. Thus, H2 is actually an exogenously produced gas, which either is passed as flatus, or diffuses into the body and is exhaled. In the adult, a fairly constant fraction is expired, providing a reliable indicator of total colonic H2 production. Breath H2 analysis currently represents a useful clinical means of testing adults and older children for the malabsorption of CHO. Noninvasive and easy procedures for the collection of expired air have encouraged their increasingly widespread use in pediatrics. Evidence to date suggests that breath H2 analysis may provide the best available method for estimating semiquantitatively the degree of CHO malabsorption. The association of the results of breath H2 analysis with other clinical measures of CHO digestion and absorption is expected, but discrepancies can also be anticipated based on the nature of this particular trace gas method. The interpretation of the results of breath H2 analysis in neonates and young infants remains especially problematic because of confounding variables which are difficult to control and are measured infrequently.

show abstract

Section: Methodsmentioning

confidence: 99%

Breath Hydrogen Analysis

Ostrander,

Cohen,

Hopper

et al. 1983

J. pediatr. gastroenterol. nutr.

View full text Add to dashboard Cite

show abstract

“…A major disadvantage of inhibitor-based elution schemes is the above mentioned dominant role of surface desorption kinetics on the efficiency of Con A affinity columns (12). We and others have previously pointed out the extreme sluggishness of this process for small monovalent eluities (3-5, [12][13][14]. The desorption of such species from immobilized Con A is very slow (approximately 1 s'1) compared to the rates observed for the desorption of small solutes from a reversed-phase column (>100 s'1) (15).…”

Section: Literature Citedmentioning

confidence: 98%

“…Research grade He was used as the carrier gas with the TCD, USD, and HID. In addition, for most analyses with the HID, the He carrier gas contained 25-30 ppmv Ne as a dopant (13). All gases and gas mixtures were supplied by Air Products and Chemicals, Inc. (Allentown, PA).…”

Section: Introductionmentioning

confidence: 99%

Calcium chabazite adsorbent for the gas chromatographic separation of trace argon-oxygen mixtures

Maroulis¹,

Coe²

1989

Anal. Chem.

View full text Add to dashboard Cite

Calcium chabazite used as a gas chromatographic packing provides a practical means for analyzing trace levels of a variety of permanent gases including oxygen and argon. An outstanding feature of properly activated calcium chabazite is its ability to resolve argon and oxygen at temperatures above 343 K. The level of dehydration achieved for this adsorbent has a direct Influence on its efficiency and ability to resolve Ar and 02. In addition, we found that treating the chabazite at elevated temperature in an oxidizing atmosphere improves the resolution and lowers the detectability limits for determining oxygen. Part-per-billion levels of Ne, Ar, 02, N2, CH4, and CO could be measured by using a calcium chabazite column, in combination with a helium ionization detector. The column efficiency and resolution of this adsorbent were measured as a function of corrected flow rate and column temperature for Ar-02 mixtures. Trace Ar and 02 were base-line-resolved In under 2 min by using a 6-ft column of this adsorbent at 343 K. Thus, calcium chabazite provides a practical adsorbent for analyzing a wide variety of gases with conventional instrumentation.

show abstract