Gas-Liquid Chromatographic-Thermal Energy Analyzer Determination of N-Nitrosodimethylamine in Beer at Low Parts per Billion Level

1981 ◽  
Vol 64 (4) ◽  
pp. 933-938
Author(s):  
Nrisinha P Sen ◽  
Stephen Seaman
Keyword(s):  
Detection Limit ◽  
Thermal Energy ◽  
Atmospheric Pressure ◽  
Internal Standard ◽  
Sulfamic Acid ◽  
Energy Analyzer ◽  
Pressure Extraction ◽  
Acidic Conditions ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatographic (GLC) procedure is described for the determination of low ppb levels of N-nitrosodimethylamine (NDMA) in beer. The sample is treated with sulfamic acid under acidic conditions followed by alkalinization with dilute KOH, distillation at atmospheric pressure, extraction of NDMA from alkaline aqueous distillate with dichloromethane, concentration of dichloromethane extract by Kuderna-Danish concentrator, and, finally determination by a GLC-thermal energy analyzer technique with N-nitrosodipropylamine (NDPA) as an internal standard. The method gave results comparable with 2 other well established methods. Recoveries of added NDMA, N-nitrosodiethylamine, and NDPA at levels ranging from 0.08 to 10 ppb were 75-112, 86-115, and 85-109%, respectively. Five replicate analyses of a beer sample gave a mean NDMA concentration (corrected for recovery) of 2.21 ± 0.08 ppb (± SD). Minimum detection limit of the method is about 0.1 ppb.

Determination of /V-Nitrosodipropylamine in Trifluralin Emulsifiable Concentrates Using Minicolumn Cleanup and Gas Chromatography with Thermal Energy Analyzer

1988 ◽  
Vol 71 (2) ◽  
pp. 333-336
Author(s):  
Dave Wotherspoon ◽  
Ralph Hindle
Keyword(s):  
Gas Chromatography ◽  
Thermal Energy ◽  
Internal Standard ◽  
Energy Analyzer ◽  
Quick Method ◽  
Coefficients Of Variation ◽  
Significant Difference ◽  
Artifact Formation ◽  
And Control

Abstract A quick method for determining /V-nitrosodipropylamine (NDPA) levels in trifluralin emulsifiable concentrate formulations is described. At least 18 samples can be analyzed at one time in a minimum of fumehood space, with up to 90% savings on solvents and materials. A sample aliquot is mixed with a solution containing nitrosamine recovery standards, and nitrosamines are separated by minicolumn cleanup. Internal standard is added directly to the eluate containing the nitrosamines, and levels are determined by gas chromatography with thermal energy analyzer. Recoveries of spiked nitrosamines ranged from 98 to 102%. Coefficients of variation for samples containing 0.5 ppm NDPA are 13%. Minimum detectable limit, calculated as 3 times the noise, is 0.06 ppm. Comparison with the method formerly used by this laboratory shows no significant difference in the analytical results at 95% confidence limits, and control experiments were performed to ensure that there was no artifact formation of NDPA.

Gas-Liquid Chromatographic-Thermal Energy Analyzer Method for N-Nitrosodiethanolamine in Cosmetics

1981 ◽  
Vol 64 (6) ◽  
pp. 1474-1478
Author(s):  
Donald B Black ◽  
Robert C Lawrence ◽  
Edward G Lovering ◽  
James R Watson
Keyword(s):  
Thermal Energy ◽  
Room Temperature ◽  
Internal Standard ◽  
Ethylene Dichloride ◽  
Gas Liquid Chromatography ◽  
Energy Analyzer ◽  
Cosmetic Products ◽  
Aqueous Mixture ◽  
Aqueous Layer ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatography-thermal energy analyzer (GLC-TEA) method has been developed for the quantitation of N-nitrosodiethanolamine (NDELA) in a variety of cosmetic products. Samples are cleaned up by a preliminary shakeout of an aqueous mixture of the cosmetic with ethylene dichloride, followed by removal of other polar and nonpolar constituents from the aqueous layer with commercial extraction columns, separation cartridges, and selected solvents. Common transnitrosating 1,3-diol preservatives sometimes found in cosmetics were eliminated after conversion to less polar cyclic boronates. The isolated NDELA fraction was trimethylsilylated at room temperature and the product was subjected to GLC-TEA, with N, N’-dinitrosopiperazine (DNPiz) used as the internal standard. Recoveries of NDELA from spiked samples usually ranged from 60 to 90%. The limit of detectability was about 5-10 ppb. The identity of NDELA was confirmed by GLC-mass spectrometry.

Determination of N-Nitrosodimethylamine in Nonfat Dry Milk: Collaborative Study

1984 ◽  
Vol 67 (2) ◽  
pp. 232-236
Author(s):  
Nrisinha P Sen ◽  
Stephen Seaman ◽  
K Karpinsky ◽  
◽  
M Castegnaro ◽  
...  
Keyword(s):  
Thermal Energy ◽  
Collaborative Study ◽  
Sulfamic Acid ◽  
Complete Data ◽  
Energy Analyzer ◽  
Coefficients Of Variation ◽  
Dry Milk ◽  
Repeatability And Reproducibility ◽  
Nonfat Dry Milk

Abstract Ten laboratories participated in a collaborative study of a method for the determination of JV-nitrosodimethylamine (NDMA) in nonfat dry milk. NDMA is eluted with dichloromethane from a mixture of Celite, acidic sulfamic acid, and nonfat dry milk (all packed in a chromatography column), concentrated in a Kuderna-Danish concentrator, and finally analyzed by a GC-thermal energy analyzer technique. Ten samples were studied: 6 were naturally contaminated (NDMA levels 0.38- 3.56 ppb) and 4 were spiked with known levels (0.96 and 3.2 ppb) of NDMA. The coefficients of variation (CV) of the complete data for the naturally contaminated samples (excluding the 2 samples containing the lowest levels) were 8.5% and 22.5% for repeatability and reproducibility, respectively. The corresponding CVs for the spiked samples were 14.4% and 20.4%, respectively. The percent recoveries of the added NDMA in the spiked samples (at the 2 levels indicated above) were 101.6 ± 3.2 (omitting 1 outlier) and 95 ∓ 2.1, respectively. The method has been adopted official first action.

Determination of N-Nitrosodimethylamine Levels in Some Canadian 2,4-D Amine Formulations

1987 ◽  
Vol 70 (1) ◽  
pp. 49-51
Author(s):  
Ralph W Hindle ◽  
J Fred Armstrong ◽  
Adeline A Peake
Keyword(s):  
Thermal Energy ◽  
Internal Standard ◽  
Packing Material ◽  
Dichlorophenoxyacetic Acid ◽  
Energy Analyzer ◽  
Gas Chromatograph ◽  
Canadian Market ◽  
Sample Aliquot ◽  
2,4 Dichlorophenoxyacetic Acid

Abstract Levels of/V-nitrosodimethylamine (NDMA) were determined in 112 samples of 2,4-dichlorophenoxyacetic acid, (2,4-D), formulated as the dimethylamine salt, collected over a 2 year period from products on the Canadian market. A sample aliquot is partitioned with dichloromethane, and the co-extracted dimethylamine is removed by cleanup on a silica gel column. The eluates containing NDMA are concentrated, an internal standard of /V-nitrosodipropylamine is added, and nitrosamine levels are determined using a gas chromatograph interfaced with a thermal energy analyzer. Recoveries of NDMA and N-nitrosodiethylamine spiked into samples were 103 ± 16 and 96.3 ± 9.8%, respectively. Of the 112 samples analyzed, 92 were below 1 part per million (ppm) relative to the amount of 2,4-D in the samples, 16 were between 1 and 5 ppm, and 4 were greater than 5 ppm. The gas chromatographic column used is compared to a conventional packing material for volatile nitrosamine analysis. Formation of NDMA during cleanup and analysis was shown not to occur.

Sensitive Determination of Zearalenone and α-Zearalenol in Barley and Job's-Tears by Liquid Chromatography with Fluorescence Detection

1993 ◽  
Vol 76 (5) ◽  
pp. 1006-1009 ◽  
Author(s):  
Touicm Tanaka ◽  
Reiko Teshima ◽  
Hideharu Ikebuchi ◽  
Jun-Ichi Sawada ◽  
Tadao Terao ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Detection Limit ◽  
Fluorescence Detection ◽  
Reliable Method ◽  
Internal Standard ◽  
Reversed Phase ◽  
Job’S Tears ◽  
Sensitive Determination ◽  
Liquid Chromatographic

Abstract A sensitive and reliable method for liquid chromatographic (LC) determination of zearalenone and α-azearalenol in barley and Job's-tears was investigated. The method by which these toxins were determined involves addition of an internal standard (zearalenone 6'-oxime) to barley and Job's-tears samples. Extracts from grain samples were cleaned up by passage through chromatography on piperidinohydroxypropyl Sephadex LH-20 as a lipophilic gel. Individual toxins were resolved by LC on a reversed-phase (ODS) column with fluorescence detection. The detection limit is estimated to be 0.2 ng for zearalenone and α-zearalenol standards. Known amounts of zearalenone and α-azearalenol (25-1250 ng) were added to a barley sample (5 g). Average recoveries for α-zearalenol and zearalenone, respectively, ranged from 96 to 102% (mean CV, 3.6%) and from 96 to 103% (mean CV, 3.3%). This method is applicable to determination of α-zearalenol and zearalenone in barley and Job's-tears with satisfactory sensitivity and accuracy.

Gas-Liquid Chromatographic-Thermal Energy Analyzer Determination of N-Nitrosodimethylamine in Beer: Collaborative Study

1982 ◽  
Vol 65 (3) ◽  
pp. 720-729
Author(s):  
Nrisinha P Sen ◽  
Stephen Seaman ◽  
Mikelis Bickis ◽  
◽  
M Castegnaro ◽  
...  
Keyword(s):  
Thermal Energy ◽  
Collaborative Study ◽  
Variance Analysis ◽  
Energy Analyzer ◽  
Laboratory Sample ◽  
Coefficients Of Variation ◽  
Percent Recovery ◽  
Repeatability And Reproducibility ◽  
Liquid Chromatographic

Abstract The GLC/TEA method for N-nitrosodimethylamine (NDMA) in beer was studied collaboratively by 13 laboratories from 7 countries. Collaborators were asked to analyze a total of 10 randomly labeled samples of beer consisting of the following duplicates: a naturally contaminated commercial beer; a beer extremely low (ca 0.1 ppb) in NDMA; and the low NDMA beer spiked with 0.5,1.9, and 5.0 ppb NDMA. The pooled repeatability and reproducibility coefficients of variation (CV) for all samples were 17% and 27%, respectively. However, when data from 2 laboratories (outliers) were omitted, the corresponding CV values improved considerably (11% and 15%, respectively). Variance analysis showed the presence of a significant laboratory-sample interaction when all data were used for analysis, but this interaction disappeared when data from the 2 outlying laboratories were excluded. The pooled percent recovery of the overall method (omitting outliers) was 101.4 ± 3.5. All the laboratories detected NDMA in the low NDMA beer. The method was adopted official first action.

Liquid Chromatographic Determination of Sulfamoyldapsone in Swine Tissues

1987 ◽  
Vol 70 (6) ◽  
pp. 1031-1032
Author(s):  
Yuuko S Endoh ◽  
Ryozo Yamaoka ◽  
Nobuo Sasaki
Keyword(s):  
Detection Limit ◽  
Quantitative Determination ◽  
Chromatographic Determination ◽  
Alumina Column ◽  
Average Recovery ◽  
Diaminodiphenyl Sulfone ◽  
Alumina Column Chromatography ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method is described for the quantitative determination of sulfamoyldapsone (2-sulfamoyl-4,4'-diaminodiphenyl sulfone) in swine muscle, liver, kidney, and fat. Sulfamoyldapsone was extracted from tissues with acetonitrile saturated with n-hexane. The extract was washed with n-hexane saturated with acetonitrile, concentrated, and cleaned up by alumina column chromatography. Sulfamoyldapsone was separated on an ODS column by using acetonitrile-methanol-water (6 + 18 + 76) and was detected at 292 nm. Overall average recovery of sulfamoyldapsone added to tissues at levels of 0.1 and 0.5 /μg/g was 93.3% ± 6.0. Detection limit was 0.02 μg/g in these tissues.

scholarly journals Determination of Finasteride in Tablets by High Performance Liquid Chromatography

2007 ◽  
Vol 4 (1) ◽  
pp. 109-116 ◽  
Author(s):  
K. Basavaiah ◽  
B. C. Somashekar
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Calibration Graph ◽  
Official Method ◽  
Pharmaceutical Dosage Forms ◽  
Bulk Drug ◽  
Liquid Chromatographic

A rapid, highly sensitive high performance liquid chromatographic method has been developed for the determination of finasteride(FNS) in bulk drug and in tablets. FNS was eluted from a ODS C18reversed phase column at laboratory temperature (30 ± 2°C) with a mobile phase consisting of methanol and water (80+20) at a flow rate of 1 mL min-1with UV detection at 225 nm. The retention time was ∼ 6.1 min and each analysis took not more than 10 min. Quantitation was achieved by measurement of peak area without using any internal standard. Calibration graph was linear from 2.0 to 30 μg mL-1with limits of detection (LOD) and quantification (LOQ) being 0.2 and 0.6 μg mL-1, respectively. The method was validated according to the current ICH guidelines. Within-day co efficients of variation (CV) ranged from 0.31 to 0.69% and between-day CV were in the range 1.2-3.2%. Recovery of FNS from the pharmaceutical dosage forms ranged from 97.89 – 102.9 with CV of 1.41-4.13%. The developed method was compared with the official method for FNS determination in its tablet forms.

Determination of nitroaromatics in biosludges with a gas chromatograph/thermal energy analyzer

1983 ◽  
Vol 55 (6) ◽  
pp. 889-892 ◽  
Author(s):  
John H. Phillips ◽  
Robert J. Coraor ◽  
Steven R. Prescott
Keyword(s):  
Thermal Energy ◽  
Energy Analyzer ◽  
Gas Chromatograph
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