scholarly journals The Determination of the Mean Degree of Paraformaldehyde by Gas Chromatography and Titration Method

1965 ◽  
Vol 68 (3) ◽  
pp. 477-480 ◽  
Author(s):  
Morio TSUGE ◽  
Shigeyuki TANAKA
Keyword(s):  
Gas Chromatography ◽  
Titration Method ◽  
The Mean

scholarly journals Solid-Phase Extraction and Gas Chromatography with Mass Spectrometric Determination of Capsaicin and Some of Its Analogues from Chili Peppers (Capsicum spp.)

1999 ◽  
Vol 82 (6) ◽  
pp. 1399-1405 ◽  
Author(s):  
Philemon Manirakiza ◽  
Adrian Covaci ◽  
Paul Schepens
Keyword(s):  
Gas Chromatography ◽  
Quantitative Determination ◽  
Solid Phase ◽  
Accurate Method ◽  
Mass Spectrometric ◽  
Phase Extraction ◽  
Capsicum Spp ◽  
The Mean ◽  
Chili Peppers

Abstract A rapid and accurate method has been developed for the quantitative determination of capsaicin and its most important analogues, dihydrocapsaicin and nordihydrocapsaicin in chili peppers. These components were extracted with methylene chlo ride and separated from interfering substances with activated charcoal. Further cleanup on Florisil cartridges and elution with ethyl acetate were performed before gas chromatographic with mass spectrometric quantitation. The concentrations found were 440 ± 64 μg/g capsaicin, 81 ± 10 μg/g dihydrocapsaicin, and 11 ± 2 μg/g nordihydrocapsaicin. The mean recovery values for triplicate analysis were between 85-94%.

Gas Chromatographic Determination of Deoxynivalenol in Wheat with Electron Capture Detection: Collaborative Study

1986 ◽  
Vol 69 (5) ◽  
pp. 899-901 ◽  
Author(s):  
George M Ware ◽  
Octave J Francis ◽  
Allen S Carman ◽  
Shia S Kuan ◽  
◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Electron Capture ◽  
Collaborative Study ◽  
Control Sample ◽  
Chromatographic Determination ◽  
Electron Capture Detection ◽  
Average Recovery ◽  
Repeatability And Reproducibility ◽  
The Mean

Abstract Ten laboratories participated in a collaborative study of a method for the determination of deoxynivalenol in wheat by gas chromatography with electron capture detection. Each laboratory analyzed 6 samples in duplicate. Each collaborator received samples spiked at the 100.3, 501.3, and 1002.6 ng/g levels; a control sample; and 2 naturally contaminated samples. The average recovery (outliers excluded) for the spiked samples was 92.2%. The mean repeatability and reproducibility, respectively, were 32.2 and 41.3% for the spiked samples and 30.9 and 47.6% for the naturally contaminated samples. The method was adopted official first action.

Gas Chromatographic/Nitrogen-Phosphorus Detection Method for Determination of Ethylene Thiourea in Finished Drinking Waters: Collaborative Study

1993 ◽  
Vol 76 (5) ◽  
pp. 1113-1120 ◽  
Author(s):  
James E Longbottom ◽  
Kenneth W Edgell ◽  
Elizabeth J Erb ◽  
Viorica Lopez-Avila ◽  
◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Drinking Water ◽  
Drinking Waters ◽  
Relative Standard ◽  
The Mean ◽  
Ethylene Thiourea ◽  
Standard Deviations ◽  
Nitrogen Phosphorus Detector ◽  
Nitrogen Phosphorus

Abstract A joint U.S. Environmental Protection Agency (USEPA)-AOAC interlaboratory method validation study was conducted on USEPA National Pesticide Survey (NPS) Method 6, "Determination of Ethylene Thiourea (ETU) in Finished Drinking Water by Gas Chromatography with a Nitrogen-Phosphorus Detector." The purpose of the study was to determine and compare the mean recoveries and precision for determination of ETU in reagent water and finished drinking waters. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with ETU at 6 concentrations levels, prepared as 3 Youden pairs. In the method, the test water is extracted by passing the sample through an absorbent matrix type tube. ETU is recovered from the tube with methylene chloride, the extract is solvent-exchanged to ethyl acetate, and an aliquot of each extract is analyzed by gas chromatography using a nitrogen-phosphorus detector. Twelve laboratories participated in the study. Data were analyzed using a USEPA computer program, which measured recovery and precision for ETU and compared the performance of the method between the 2 water types. Over the concentration range tested, the mean percent recoveries of ETU were 82-92% in reagent water and 85-98% in finished drinking water. The range of the betweenlaboratory relative standard deviations (RSDR) for the 6 concentrations was 5-24% in reagent water, but was only 4-9% in finished drinking water. The range of the within-laboratory relative standard deviations (RSDr) was 6-14% for reagent water and 6- 10% for finished drinking water. Results for the 2 water matrixes showed no statistically significant differences. The method has been adopted first action by AOAC International for determination of ETU in finished drinking waters.

Headspace single-drop microextraction coupled with gas chromatography electron capture detection of butanone derivative for determination of iodine in milk powder and urine

2013 ◽  
Vol 67 (10) ◽  
Author(s):  
Meihua Hu ◽  
Haiying Chen ◽  
Yong Jiang ◽  
Huifang Zhu
Keyword(s):  
Gas Chromatography ◽  
Detection Method ◽  
Milk Powder ◽  
Electron Capture Detection ◽  
Interference Effects ◽  
Single Drop ◽  
Acidic Media ◽  
Single Drop Microextraction ◽  
The Mean

AbstractA new detection method using headspace single-drop microextraction (HS-SDME) coupled to gas chromatography (GC) was established to determine the iodine in milk powder and urine. The derivative from the reaction between iodine and butanone in the acidic media was extracted into a micro-drop then determined by GC-ECD. With the optimisation of HS-SDME and derivatisation, the calibration curve showed good linearity within the range of 0.004–0.1 μg mL−1 (0.004–0.1 μg g−1) (R 2 = 0.9991), and the limits of detection for milk powder and urine were 0.0018 μg g−1 and 0.36 μg L−1, respectively. The mean recoveries of milk powder and urine were 90.0–107 % and 89.4–101 % with mean RSD of 1.7–3.4 % and 2.7–3.3 %, respectively. This detection method affords a number of advantages, such as being simple, rapid, and inexpensive, with low organic solvent consumption, and is remarkably free from interference effects, rendering it an efficient method for the determination of iodine in milk powder and urine samples.

scholarly journals Determination of Glyphosate and Aminomethylphosphonic Acid in Crops by Capillary Gas Chromatography with Mass-Selective Detection: Collaborative Study

2001 ◽  
Vol 84 (3) ◽  
pp. 823-846 ◽  
Author(s):  
Philip L Alferness ◽  
Lawrence A Wiebe ◽  
L Anderson ◽  
O Bennett ◽  
M Bosch ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Capillary Gas Chromatography ◽  
Collaborative Study ◽  
Selective Detection ◽  
Aminomethylphosphonic Acid ◽  
Relative Standard ◽  
The Mean

Abstract A collaborative study was conducted to validate a method for the determination of glyphosate and aminomethylphosphonic acid (AMPA) in crops. The analytes are extracted from crops with water, and the crude extracts are then subjected to a cation exchange cleanup. The analytes are derivatized by the direct addition of the aqueous extract into a mixture of heptafluorobutanol and trifluoroacetic anhydride. The derivatized analytes are quantitated by capillary gas chromatography with mass-selective detection (MSD). The collaborative study involved 13 laboratories located in 5 countries 12 laboratories returned valid data sets. The crops tested were field corn grain, soya forage, and walnut nutmeat at concentrations of 0.050, 0.40, and 2.0 mg/kg. The study used a split-level pair replication scheme with blindly coded laboratory samples. Twelve materials were analyzed, including 1 control and 3 split-level pairs for each matrix, 1 pair at each nominal concentration. For glyphosate, the mean recovery was 91%, the average intralaboratory variance, the repeatability relative standard deviation (RSDr), was 11%, and the interlaboratory variance, the reproducibility relative standard deviation (RSDR), was 16%. For AMPA, the mean recovery was 87%, the RSDr was 16%, and the RSDR was 25% at mg/kg levels.

Capillary Gas Chromatographic Determination of Some Chlorobiphenyls in Eel Fat: Interlaboratory Study

1985 ◽  
Vol 68 (4) ◽  
pp. 756-759
Author(s):  
Louis G M Th Tuinstra ◽  
Arie H Roos ◽  
Geziena A Werdmuller
Keyword(s):  
Gas Chromatography ◽  
Standard Deviation ◽  
Coefficient Of Variation ◽  
Capillary Gas Chromatography ◽  
Chromatographic Determination ◽  
Interlaboratory Study ◽  
Analytical Results ◽  
The Mean

Abstract A method for determination of 6 individual chlorobiphenyls in eel fat, based on saponification of the sample and determination with capillary gas chromatography, was studied collaboratively. Eleven laboratories submitted analytical results in duplicate for 6 individual chlorobiphenyls on 2 naturally contaminated eel fat samples. The reproducibility coefficient of variation was about 14% at the 1 mg/kg level for each chlorobiphenyl compound and about 23% at the 0.1 mg/kg level. For each compound, the mean recovery was about 90% with a standard deviation varying from 7 to 9%.

scholarly journals Accurate Estimation of Bicarbonate and Acetic Acid Concentrations with Wider Ranges in Anaerobic Media Using Classical FOS/TAC Titration Method

2021 ◽  
Vol 11 (24) ◽  
pp. 11843
Author(s):  
Xiaojun Liu ◽  
Laura André ◽  
Maël Mercier-Huat ◽  
Jean-Marie Grosmaître ◽  
André Pauss ◽  
...  
Keyword(s):  
Sodium Acetate ◽  
Fatty Acid Content ◽  
Total Alkalinity ◽  
Accurate Estimation ◽  
Acid Base ◽  
Titration Method ◽  
Simulation And Experiment ◽  
The Mean ◽  
Anaerobic Media

The determination of a volatile fatty acid content (FOS) and total alkalinity (TAC) can be carried out using Nordmann’s FOS/TAC titration method developed in the 1970s. This two-point titration (pH = 5 and 4.4) can be simply implemented and is widely employed by both the academic and industrial worlds. However, the present study proves that Nordmann’s method is only valid in limited ranges, since the titration of one FOS and TAC has an impact on the determination of the other, especially in extreme conditions. The present work develops a numerical tool with Scilab simulating the acid–base equilibria of titration. The program is efficient in predicting the experimental equivalent volumes obtained from Nordmann’s method with different combinations of sodium acetate and sodium bicarbonate contents. The mean absolute percentage errors (MAPE) between the simulation and experiment are below 7%. Two new formulas are developed, considering both equivalent volumes at pH = 5 and 4.4 to calibrate FOS and TAC values. The proposed formulas show their good performance in predicting various combinations of FOS and TAC contents in an anaerobic digestate at TAC ranging from 0 to 20,000 mg CaCO3·L−1 and FOS ranging from 0 to 31,000 mg HAc·L−1.

Detection of Circulating Tissue Factor and Factor VII in a Normal Population

1996 ◽  
Vol 75 (05) ◽  
pp. 772-777 ◽  
Author(s):  
Sybille Albrecht ◽  
Matthias Kotzsch ◽  
Gabriele Siegert ◽  
Thomas Luther ◽  
Heinz Großmann ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Normal Population ◽  
Mean Value ◽  
Factor Vii ◽  
Significant Difference ◽  
Age Dependent ◽  
The Mean ◽  
Highly Correlated ◽  
And Gender

SummaryThe plasma tissue factor (TF) concentration was correlated to factor VII concentration (FVIIag) and factor VII activity (FVIIc) in 498 healthy volunteers ranging in age from 17 to 64 years. Immunoassays using monoclonal antibodies (mAbs) were developed for the determination of TF and FVIIag in plasma. The mAbs and the test systems were characterized. The mean value of the TF concentration was 172 ± 135 pg/ml. TF showed no age- and gender-related differences. For the total population, FVIIc, determined by a clotting test, was 110 ± 15% and the factor VIlag was 0.77 ± 0.19 μg/ml. FVII activity was significantly increased with age, whereas the concentration demonstrated no correlation to age in this population. FVII concentration is highly correlated with the activity as measured by clotting assay using rabbit thromboplastin. The ratio between FVIIc and FVIIag was not age-dependent, but demonstrated a significant difference between men and women. Between TF and FVII we could not detect a correlation.

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