Study on the precision of the activated charcoal solvent desorption procedure - Correlation of desorption efficiencies

1981 ◽  
Vol 46 (6) ◽  
pp. 1332-1347 ◽  
Author(s):  
Martin Koval
Keyword(s):  
Activated Charcoal ◽  
Carbon Disulphide ◽  
Internal Standard ◽  
Standard Addition ◽  
Published Data ◽  
Single Factor ◽  
Gas Chromatograph ◽  
Model Compounds ◽  
Single Factor Analysis ◽  
Acceptable Agreement

The described method uses activated charcoal sampling tubes for air sampling. Adsorbed compounds are eluted by the static desorption procedure with 1 ml of carbon disulphide, 0.5 ml of the supernatant is filtered off and, after internal standard addition, analysed on a gas chromatograph. Using synthetic calibration mixtures of model organic compounds with air, cumulative sampling and desorption efficiencies for 24 substances were determined for concentration ranges and sample volumes according to current Czechoslovak hygienic standards. Experimental results were treated with the single factor analysis of variance and the precision of the described procedure was estimated for the studied model compounds on the basis of residual sums of squares. Calculated values of cumulative sampling and desorption efficiencies and their precisions were compared with available published data and an acceptable agreement was found. In addition to that, cumulative sampling and desorption efficiencies were also found to be significantly correlated to molar volumes and other related molecular properties for some types of compounds.

Flame ionization detector response to coeluting hydrocarbons and carbon disulphide and its application to the determination of the sum of C6-C11 alkanes and cycloalkanes in air

1983 ◽  
Vol 48 (3) ◽  
pp. 722-734
Author(s):  
Martin Koval
Keyword(s):  
Carbon Disulphide ◽  
Internal Standard ◽  
Calibration Procedure ◽  
Detector Response ◽  
Column Temperature ◽  
Flame Ionization ◽  
Other Substances ◽  
Flame Ionisation Detector ◽  
Ionisation Detector

The flame ionisation detector response to C6-C11 aliphatic hydrocarbon solutions in carbon disulphide in the concentration range between 1.3-9.5 mg ml-1 retained lineary despite the excess of solvent entering the detector simultaneously with the analyte. Pure carbon disulphide exhibited a small positive detector response which did not interfere in calibration procedure and which, under certain GC conditions, inverted to negative values. This response was not proportional to the injected volume and was strongly influenced by the column temperature and/or bleed. On the basis of these findings, a method compatible with the widely used charcoal tube carbon disulphide desorption procedure was developed and evaluated. It consists of static desorption of the sum of aliphatic alkanes and cycloalkanes from the activated charcoal after which an internal standard is added to the supernatant eluate. The resulting carbon disulphide solution is analysed on a highly polar stationary phase 1,2,3-tris(2-cyanoethoxy)propane where the solvent and the analyte coelute in a single peak, the height of which is practically proportional to the sum of alkanes and cycloalkanes present. This also makes determinations of other substances present in the sample more simple. The field test of the proposed method yielded values comparable in precision and accuracy with a control infrared spectrophotometric method.

scholarly journals Significance of pepsinogen in screening for gastric intestinal metaplasia in Guangdong, China

2021 ◽  
Vol 49 (2) ◽  
pp. 030006052199049
Author(s):  
Xujuan Liu ◽  
Min Zhang ◽  
Riyu Luo ◽  
Keran Mo ◽  
Xingxiang He
Keyword(s):  
Logistic Regression ◽  
Intestinal Metaplasia ◽  
Single Factor ◽  
Antibody Testing ◽  
Cross Sectional ◽  
Gastric Intestinal Metaplasia ◽  
Risk Detection ◽  
Tree Models ◽  
Single Factor Analysis ◽  
Serological Biomarkers

Objective Diagnosis of gastric intestinal metaplasia (GIM) relies on gastroscopy and histopathologic biopsy, but their application in screening for GIM is limited. We aimed to identify serological biomarkers of GIM via screening in Guangdong, China. Methods Cross-sectional field and questionnaire data, demographic information, past medical history, and other relevant data were collected. Blood samples were collected for pepsinogen (PG)I, PGII, gastrin-17, and Helicobacter pylori antibody testing, and gastroscopy and histopathologic biopsy were performed. Single factor and logistic regression analyses were used to evaluate the correlation between these indicators and GIM, and decision tree models were used to determine the cut-off points between indicators. Results Of 443 participants enrolled, 87 (19.6%) were diagnosed with GIM. Single factor analysis showed that pepsin indicators (PGI, PGII, and PGI/PGII ratio) and the factors Mandarin as native language, urban residency, hyperlipidemia, and age were associated with GIM. Logistic regression analysis showed that PGI and age were associated with GIM. Conclusions Age is an important factor for predicting GIM progression; age >60 years increased its risk. Detection of GIM was higher in individuals with PGI levels >127.20 ng/mL, which could be used as a threshold indicating the need to perform gastroscopy and histopathologic biopsy.

scholarly journals Improving Strength and Quality of Epitendinous Repairs

Hand ◽  
2018 ◽  
Vol 15 (4) ◽  
pp. 495-501
Author(s):  
Angel Farinas ◽  
Michael Stephanides ◽  
Steven Schneeberger ◽  
Alonda Pollins ◽  
Nancy Cardwell ◽  
...  
Keyword(s):  
Factor Analysis ◽  
Analysis Of Variance ◽  
Statistical Significance ◽  
Single Factor ◽  
Single Thread ◽  
A2 Pulley ◽  
Suture Thread ◽  
Single Factor Analysis ◽  
Single Suture

Background: Epitendinous sutures not only join the 2 severed tendon edges but also supply strength and support to the repair. Multiple techniques have been described, but none of them include another thread of suture. This could potentially increase the strength of the repair without affecting gliding. Methods: Caprine tendons were harvested, transected, and sutured with 6-0 Prolene. Four groups were created: single thread running (SR), single thread locking (SL), double thread running (DR), and double thread locking (DL). An Instron 5542 was used to pull the repaired tendons apart, and the energy at the break was calculated (gf/mm). For gliding resistance, we harvested a human A2 pulley. A pre- and postrepair value was obtained, and a ratio was elaborated. A single-factor analysis of variance and independent sample t tests were performed. Results: The SR group had a mean energy at break of 9339.71 ± 1630.212 gf/mm; the SL group, 9629.96 ± 1476.45 gf/mm; and the DR group, 9600.221 ± 976.087 gf/mm, with no statistical significance. The DL group was significantly higher at 14 740.664 ± 2596.586 gf/mm ( P < .05). When comparing SR with DL for gliding, SR had less than half of the resistance than DL (0.018 ± 0.004 and 0.049 ± 0.015 N/mm, respectively), with statistical significance ( P < .05). Conclusion: Using a single suture thread for running epitendinous repair is no different than locking with a single thread or using an extra thread in a running fashion. Performing a double suture thread with a locking technique is significantly stronger than the previously mentioned repairs, with the disadvantage of more resistance at the pulley.

scholarly journals Conversion of sulphur compounds into light gas oil: I. Kinetics of the conversion of model compounds

2002 ◽  
Vol 56 (2) ◽  
pp. 68-75
Author(s):  
Jasna Jankovic ◽  
Dejan Skala
Keyword(s):  
Chemical Industry ◽  
Heterocyclic Compounds ◽  
Published Data ◽  
Gas Oil ◽  
Model Compounds ◽  
Sulphur Compounds ◽  
Middle Fraction ◽  
Light Gas Oil ◽  
Reactor Calculation ◽  
Kinetics Of

The problem of sulfur compounds conversion, particularly heterocyclic compounds, from the middle fraction of crude oil (light gas oil) was analyzed and will be published in several articles in the Chemical Industry Journal. Published data in the literature, covering the conversion of tiophene, benzothiophene and dibenzothiophene are presented in the first paper of this series with the goal of comparing and critically analyzing their usage for reactor calculation.

Silicon Carbide Ceramic Turning Process Design and Parameter Analysis

2014 ◽  
Vol 800-801 ◽  
pp. 203-207
Author(s):  
Zhen Bo Wang ◽  
Liang Zhang ◽  
Shu Zhi Li
Keyword(s):  
Silicon Carbide ◽  
Process Design ◽  
Numerical Control ◽  
Parameter Analysis ◽  
Machining Process ◽  
Analysis Method ◽  
Single Factor ◽  
Turning Process ◽  
Silicon Carbide Ceramic ◽  
Single Factor Analysis

This article mainly aims at the problem of silicon carbide ceramic mechanical turning difficult processing,by adopting the method of the numerical control turning processing.Design a special fixtures and a NC machining process to accomplish the manufacture of silicon carbide plate.And through the single factor analysis method to process parameters were analyzed.

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