Description of the thermal energy analyzer (TEA) for trace determination of volatile and nonvolatile N-nitroso compounds

Abstract Three methods, the mineral oil distillation (MOD), the dry column (DC), and a low temperature vacuum distillation (LTVD), for the determination of iV-nitrosopyrrolidine in dry-cured and pump-cured bacon were compared. Each method uses the thermal energy analyzer for the determinative step. The coefficients of variation for repeatability were 10.3% (MOD), 7.2% (DC), and 9.1% (LTVD) for the dry-cured bacon study and 8.7% (MOD), 8.5% (DC), and 7.1% (LTVD) for the pump-cured bacon study. The pooled coefficients of variation for between-method reproducibility were 11.8% for the drycured bacon and 10.8% for the pump-cured bacon. The pooled coefficients of variation for repeatability were 9.0% for the dry-cured bacon and 8.2% for the pump-cured bacon. These values compare favorably with the values from previous collaborative or validation studies of the individual methods, and the methods can be considered to be equivalent

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

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/71.2.333 ◽

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.

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Determination of Diethanolamine in Shampoo Products Containing Fatty Acid Diethanolamides by Liquid Chromatography with a Thermal Energy Analyzer

Journal of AOAC International ◽

10.1093/jaoac/88.2.592 ◽

2005 ◽

Vol 88 (2) ◽

pp. 592-594 ◽

Cited By ~ 4

Author(s):

Hardy J Chou

Keyword(s):

Acetic Acid ◽

Liquid Chromatography ◽

Fatty Acid ◽

Thermal Energy ◽

Sodium Nitrite ◽

Room Temperature ◽

Energy Analyzer

Abstract A liquid chromatography (LC) method using a thermal energy analyzer (TEA) is described for the determination of diethanolamine (DEA) in shampoo products containing fatty acid diethanolamides. DEA was converted to N-nitrosodiethanolamine (NDELA) by dissolving a portion of the product in 6M acetic acid and mixing with sodium nitrite for 1 h at room temperature. The reaction mixture was dried, dissolved in acetone, and analyzed for NDELA by LC-TEA. The recovery of DEA from 2 shampoo products at fortification levels of 25, 250, and 1000 ppm ranged from 70 to 105%. Twenty shampoo products were analyzed by this method, and 19 were found to contain DEA at levels ranging from 140 to 15 200 ppm.

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

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/67.2.232 ◽

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.

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