Insights from analysis for harmful and potentially harmful constituents (HPHCs) in tobacco products.

A total of 20 commercial cigarette and 16 commercial smokeless tobacco products were assayed for 96 compounds listed as harmful and potentially harmful constituents (HPHCs) by the US Food and Drug Administration. For each product, a single lot was used for all testing. Both International Organization for Standardization and Health Canada smoking regimens were used for cigarette testing. For those HPHCs detected, measured levels were consistent with levels reported in the literature, however substantial assay variability (measured as average relative standard deviation) was found for most results. Using an abbreviated list of HPHCs, statistically significant differences for most of these HPHCs occurred when results were obtained 4-6months apart (i.e., temporal variability). The assay variability and temporal variability demonstrate the need for standardized analytical methods with defined repeatability and reproducibility for each HPHC using certified reference standards. Temporal variability also means that simple conventional comparisons, such as two-sample t-tests, are inappropriate for comparing products tested at different points in time from the same laboratory or from different laboratories. Until capable laboratories use standardized assays with established repeatability, reproducibility, and certified reference standards, the resulting HPHC data will be unreliable for product comparisons or other decision making in regulatory science.

A comprehensive evaluation of the toxicology of experimental cigarettes manufactured with banded papers.

CONTEXT: To comply with state requirements, cigarette manufacturers have added low-permeability bands to the cigarette paper. These bands can extinguish the cigarette when it is no longer being puffed by a smoker. OBJECTIVE: This study was conducted to evaluate the toxicology resulting from the addition of different types of bands to experimental cigarettes. MATERIALS AND METHODS: A battery of assays that are typically used in toxicology studies with cigarette smoke, namely smoke chemistry, in vitro mutagenicity and cytotoxicity, and inhalation studies with rats, were used to evaluate different band characteristics added to cigarette paper. RESULTS: Although differences in the amount of band material was associated with an increase in some metals measured in mainstream tobacco smoke, it was not dose responsive to any band design parameter (base paper permeability, band width, band spacing, band chalk amount, or citrate). Occasional, minor differences were produced by the different types of bands; overall, there was no increased toxicity. CONCLUSION: Although there were increases and decreases in some mainstream smoke constituents, the in vitro and in vivo testing performed demonstrated that low-permeability bands on cigarettes do not modify the toxicity of smoke inhaled by smokers.

An expanded cellular automata model for enantiomer separations using a ß-cyclodextrin stationary phase.

Chromatographic scale enantiomer separation has not been modeled using cellular automata (CA). CA uses easy to adjust equations to different enantiomers under various chromatographic conditions. Previous work has demonstrated that CA modeling can accurately predict the strength of one-to-one binding interactions between enantiomers and ß-cyclodextrin (CD) [1]. In this work, the model is expanded to a chromatographic scale grid environment in order to transform model output into HPLC chromatograms. The model accurately predicted the lack of chromatographic selectivity of mandelic enantiomers (1.05 published, 1.01 modeled) and the separation of brompheniramine enantiomers (1.13 published, 1.12 modeled) previously modeled in one-to-one interactions. By examining cyclohexylphenylglycolic acid (CHPGA) enantiomers, the model accurately predicted both the selectivity and resolution of the enantiomer peaks at varying chromatographic temperatures. Modeled changes in mobile phase pH agree with laboratory outcomes when examining peak resolution and selectivity. Changes in injection volume resulted in an increase in retention time of the modeled enantiomers as was observed in the published laboratory results.

A cellular automata model of enantiomer binding strengths to ß-cyclodextrin.

As yet, the analytical process of chromatographic enantiomer separation has not been modeled using cellular automata (CA). This approach uses mathematical systems that are easily adaptable to different enantiomer analytical binding interactions. A CA model of analyte to cyclodextrin (CD) interaction accurately (R(2)=0.9960) predicts one-to-one molecular binding strengths through correlation with experimental complex stability constants while exhibiting established chromatographic behavior (i.e. retention site dependency and band broadening). The model is expanded to enantiomer HPLC retention interactions with ß-CD that accurately predicts one-to-one binding strengths through the development of probabilistic rules and factors from chromatographic results. The proposed model predicts the strength of binding interactions and the degree of chromatographic separation (or lack thereof) of six enantiomer pairs that agree with published potential binding energies of enantiomer-(ß-CD) complexes and published experimental HPLC separations.