Development and validation of an improved method for the determination of chloropropanols in paperboard food packaging by GC-MS.

The objective of this study was to develop an improved analytical method for the determination of 3-chloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in paper-type food packaging. The established method includes aqueous extraction, matrix spiking of a deuterated surrogate internal standard (3-MCPD-d5), clean-up using Extrelut solid-phase extraction, derivatisation using a silylation reagent, and GC-MS analysis of the chloropropanols as their corresponding trimethyl silyl ethers. The new method is applicable to food-grade packaging samples using European Commission standard aqueous extraction and aqueous food stimulant migration tests. In this improved method, the derivatisation procedure was optimised; the cost and time of the analysis were reduced by using 10 times less sample, solvents and reagents than in previously described methods. Overall the validation data demonstrate that the method is precise and reliable. The limit of detection (LOD) of the aqueous extract was 0.010 mg kg(-1) (w/w) for both 3-MCPD and 1,3-DCP. Analytical precision had a relative standard deviation (RSD) of 3.36% for 3-MCPD and an RSD of 7.65% for 1,3-DCP. The new method was satisfactorily applied to the analysis of over 100 commercial paperboard packaging samples. The data are being used to guide the product development of a next generation of wet-strength resins with reduced chloropropanol content, and also for risk assessments to calculate the virtual safe dose (VSD).

Influence of emulsifier structure on lipid bioaccessibility in oil-water nanoemulsions.

The influence of several nonionic surfactants (Tween-20, Tween-40, Tween-60, Span-20, Span-60, or Span-80) and anionic surfactants (sodium lauryl sulfate, sodium stearoyl lactylate, and sodium stearyl fumarate) showed drastic differences in the rank order of lipase activity/lipid bioaccessibility. The biophysical composition of the oil and water interface has a clear impact on the bioaccessibility of fatty acids (FA) by altering the interactions of lipase at the oil-water interface. It was found that the bioaccessibility was positively correlated with the hydrophilic/lipophilic balance (HLB) of the surfactant and inversely correlated to the surfactant aliphatic chain length. Furthermore, the induction time in the jejunum increased as the HLB value increased and decreased with increasing aliphatic chain length. The rate of lipolysis slowed in the jejunum with increasing HLB and with increasing aliphatic chain length.

Automated, microprocessor controlled short path thermal desorption system for analysis of volatiles in foods.

An automated short path thermal desorption system gas chromatograph (GC) accessory was constructed to facilitate the unattended analysis of up to twelve individual samples. The system is personal computer controlled, operates directly on the GC with little or no modification, and was tested in both direct thermal and purge and trap thermal desorption mode. The apparatus was evaluated for overall performance, ruggedness, baseline blanks, efficiency, and precision. Mechanical performance was flawless and a clean baseline was obtained under high sensitivity GC-FID conditions. Linearity and precision was evaluated by quantifying butylated hydroxy toluene standards, safranal in saffron spice, and cinnamic aldehyde in cookies.

Determination of allicin, S-allylcysteine and volatile metabolites of garlic in breath, plasma or simulated gastric fluids.

Various components of garlic and aged garlic extract, including allicin, S-allylcysteine (SAC) and volatile metabolites of allicin were determined in breath, plasma and simulated gastric fluids by HPLC, gas chromatography (GC) or HPLC- and GC-mass spectrometry (MS). Data indicate that allicin decomposes in stomach acid to release allyl sulfides, disulfides and other volatiles that are postulated to be metabolized by glutathione and/or S-adenosylmethionine to form allyl methyl sulfide. SAC can be absorbed by the body and can be determined in plasma by HPLC or HPLC-MS using atmospheric pressure chemical ionization (APCI)-MS.

Direct thermal desorption-gas chromatography and gas chromatography-mass spectrometry profiling of hop (Humulus lupulus L.) essential oils in support of varietal characterization.

The use of direct thermal desorption-gas chromatography-mass spectrometry (DTD-GC-MS) and DTD-GC-flame ionization detection (DTD-GC-FID) for characterization of hop essential oils is described. Four hop varieties (Nugget, Galena, Willamette, and Cluster) from the Yakima valley (Yakima, WA) 1998 harvest were analyzed by DTD-GC-MS and DTD-GC-FID methodology. Approximately 1 g of hops was needed for the analysis. Hop samples were prepared for GC-MS and/or GC-FID profiling in approximately 20 min. More than 100 volatile compounds have been identified and quantified for each hop variety. The results were found to be in good agreement with conventional steam distillation-extraction (SDE) data. A calibration curve for determination of essential oil content in hops by DTD-GC-FID has been generated. Quantitation of hop oil content by DTD-GC-FID was shown to be in good agreement with conventional SDE data. The recovery of key oil components valuable for varietal identification was demonstrated to be highly reproducible and characteristic of each variety analyzed when DTD-GC-FID was used for analysis.

The determination of metabolites of garlic preparations in breath and human plasma.

Gas Chromatography-Mass Spectrometry (GC-MS) was the major technique used to determine various metabolites after consumption of dehydrated granular garlic and an enteric-coated garlic preparation, in breath, plasma, and simulated gastric fluids. A special short-path thermal desorption device was used as an introduction technique for the gas chromatograph for the determination of volatiles. These garlic preparations release allicin, which decomposes in stomach acid or with time in the intestine to release allyl sulfides, disulfides and other volatiles, some of which are postulated to be metabolized by glutathione and/or S-adenosylmethionine to form allyl methyl sulfide, the main sulfur containing volatile metabolite. S-Allylcysteine, a non-volatile bioactive component of aged garlic preparations, was determined in human plasma and urine by HPLC-MS using the negative ion atmospheric pressure chemical ionization mode (APcI)- MS. The technique of selected ion monitoring was used for quantitation. A synthetic internal standard of deuterated S-allylcysteine was added to the plasma or urine to ensure recovery and to obtain reliable quantitative data.

Pathway of terpene excretion by the appendix of Sauromatum guttatum.

Electron microscopy of the cells of the thermogenic appendix of Sauromatum guttatum has revealed a fusion event between pocket-like structures of the rough endoplasmic reticulum (rER) and the plasma membrane. As a result of the fusion event, many regions of the plasma membrane have paired unit membranes (four leaflets instead of two). The fusion allows the transfer of osmiophilic material from the rER pockets to the plasma membrane, where the osmiophilic material is confined to bilayer, pocket-like structures. A clear correlation is found between the presence of the osmiophilic compound and sesquiterpenes. Prior to heat production, the rER- and plasma-membrane pockets are electron dense, and sesquiterpenes are detectable only in tissue extracts. On the day of heat production, electron-translucent pockets are subsequently found and the stored sesquiterpenes are released to the atmosphere. Three sesquiterpenes have been identified by gas chromatography-mass spectrometry as alpha-copaene and beta- and alpha-caryophyllene.

Glycation of lysozyme in a restricted water environment.

Fast atom bombardment mass spectrometry (FAB) was used to determine the glycation sites of lysozyme in a restricted water environment. A 30-day incubation at 25 degrees C, and 65% relative humidity (R.H.) resulted in glycation at lysine-1 while a much shorter (3-day) incubation at 50 degrees C and 65% R.H. resulted in diglycation at lysine-1 as well as glycation at lysine-13 and lysine-33.

The effect of anti-promoters and calcium antagonists on V-79 Chinese hamster lung fibroblasts exposed to phorbol myristate acetate.

The effect of calcium antagonists and representative compounds from several classes of anti-promoters including anti-inflammatory sterols, protease inhibitors, retinoids and cyclic nucleotides on metabolic cooperation in cells treated with phorbol-12-myristate-13-acetate (PMA) was determined. Each compound was tested for its effect on metabolic cooperation and also for its ability to reverse or modify the inhibitory properties of PMA on intercellular communication at noncytotoxic exposure concentrations. Of all the compounds tested only cyclic AMP was able to antagonize the inhibitory effect of PMA. trans-Retinoic acid inhibited metabolic cooperation slightly at high exposure concentrations and acted synergistically with PMA to strongly inhibit intercellular communication in a dose-dependent manner.

The effect of some experimental parameters on the inhibition of metabolic cooperation by phorbol myristate acetate.

The effect of cell density, PMA exposure time, concentration, pre-exposure and binding activity on the recovery of V 79 HGPRT- Chinese hamster cells in the metabolic cooperation assay was determined. A PMA exposure interval of only 1 min resulted in maximum recovery of HGPRT- cells. PMA began to inhibit metabolic cooperation at a dose as low as 0.1 ng/ml final media concentration. The recovery of HGPRT- cells varied according to cell density in the presence or absence of PMA, although the magnitude of this effect was much greater in untreated cells. Pre-exposure of cells to PMA increased the recovery of both post-PMA-treated and non-treated HGPRT- cells in a dose-dependent manner. [3H]PMA was rapidly bound to or taken up by V 79 cells. These results suggest that the inhibitory effect of PMA on metabolic cooperation in V 79 cells involves receptor binding.

Inhibition of metabolic cooperation by cigarette smoke condensate and its fractions in V-79 Chinese hamster lung fibroblasts.

This study was performed to determine the usefulness of the intercellular metabolic cooperation assay for analysis of a complex mixture and to compare the results obtained with previously conducted in vivo tumor promoter assays. One hundred 2R1 cigarettes were smoked according to Federal Trade Commission guidelines and the resulting condensate was separated into a water/methanol-soluble fraction (which was further partitioned into acidic and basic components) and an organic solvent-soluble fraction (which was then chromatographed on silicic acid with petroleum ether, benzene/petroleum ether, benzene, ether, and methanol). The following fractions were positive in the metabolic cooperation assay (in decreasing order of activity): organic solvent-soluble, acidic, whole condensate, and water/methanol-soluble fractions as well as the ether, benzene, and benzene/petroleum ether eluates. The basic fraction and the petroleum ether and methanol eluates were negative. In general, the metabolic cooperation assay results were comparable to previously published results obtained on mouse skin.