Selective labeling for the identification and semi-quantification of lipid aldehydes in food products.

Lipid oxidation reactions in foods rich in healthy unsaturated fatty acids result in the formation of a wide range of oxidation products that can have adverse effects on food quality and safety. To improve the understanding of oxidation reactions and methods for their inhibition, detailed information on the type and levels of the oxidation products formed is required. Accurate measurement of lipid oxidation products, especially of the non-volatile aldehyde products, has so far been a challenge due to the low sensitivity and limited specificity of most analytical methods. Here, a novel normal-phase LC method that uses selective labeling of aldehydes and epoxides with 7-(diethylamino)coumarin-3-carbohydrazide (CHH) is described. Labeling of alkanals is quantitative within 10 h. For alkenals, conversion is only around 50% at 24 h reaction time. Detailed MS identification of all aldehydes and epoxides is possible by using high-resolution MS and data-dependent MS2 acquisition. Fluorescence detection was successfully used to quantify groups of oxidation products. Sensitivity was high enough to allow accurate quantification even in fresh mayonnaises, where levels of around only 0.3 g total aldehydes/kg oil were found. Individual species can be quantified by MS if suitable reference standards are available. If no standards can be used, semi-quantification using an average response factor is an option. Clearly, the novel derivatization method is suitable for monitoring secondary lipid oxidation products in the early stages of shelf life. This makes it an important tool for developing improved food products. Graphical abstract Selective labeling of low and high molecular weight lipid oxidation products with 7-(diethylamino) coumarin-3-carbohydrazide for identification and semi-quantification.

Hydroxyisohexyl 3-cyclohexene carboxaldehyde (lyral) in patch test preparations under varied storage conditions.

BACKGROUND: The common practice of preparing patch tests in advance has recently been called into question by researchers. It has been established that fragrance compounds are volatile and their testing efficacy may be affected by storage conditions and preparation. Allergens in fragrance mix I rapidly decrease in concentration after preapplication to test chambers. OBJECTIVES: This study aimed to investigate the volatility of hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) in petrolatum when stored in test chambers and to explore the correlation between vapor pressure and allergen loss in petrolatum during preparation and storage. METHODS: Standardized HICC in petrolatum was prepared and stored in IQ Chambers and Finn Chambers with covers at 5°C, 25°C, and 35°C, and concentration was analyzed at intervals for up to 9 days using gel permeation chromatography. RESULTS: Changes in HICC concentrations were not statistically significant at 8 hours at 5°C, 25°C, and 35°C. After 9 days, HICC concentrations were found to fall approximately 30% when stored at 35°C, 10% at 25°C, and less than 5% at 5°C. There was no significant difference between IQ and Finn chambers. CONCLUSIONS: Hydroxyisohexyl 3-cyclohexene carboxaldehyde concentrations are more stable in petrolatum than many other studied fragrance allergens, but HICC is still at risk for decreasing concentration when exposed to ambient air or heat for prolonged periods.

[Studies on GC fingerprint of volatile oil of Houttuynia cordata].

OBJECTIVE: To establish a GC fingerprint of the volatile oil of Houttuynia cordata. METHOD: The volatile oil was extracted from H. cordata by water stream distillation method, and analyzed by GC coupled with FID. RESULT: 12 bathes of samples collected from different regions were analyzed; the GC fingerprint of the volatile oil of H. cordata was subsequently established. CONCLUSION: The established GC fingerprint can be used for the identification of H. cordata.

Detection of 1,N(2)-propanodeoxyguanosine adducts in DNA of Fischer 344 rats by an adapted (32)P-post-labeling technique after per os application of crotonaldehyde.

Crotonaldehyde is an important industrial chemical to which humans and animals are ubiquitously exposed. The main intake occurs via food, tobacco smoke and possibly also via beverages. Estimation of intake via the different routes is difficult since the data available on exposure are inconsistent. Crotonaldehyde is genotoxic, mutagenic and carcinogenic and forms 1,N(2)-propanodeoxyguanosine adducts as the main DNA adducts. We have developed a (32)P-post-labeling method for these adducts based on nuclease P1 enrichment and polyethyleneimine-cellulose TLC which allows reliable detection with a detection limit of 3 adducts/10(9) nucleotides, a labeling efficiency of 80-90% and a recovery of 38%. Using this method we found crotonaldehyde adducts in different organs of Fischer 344 rats after a single gavage of high doses of 300 and 200 mg/kg body wt in the range 0.3-3.2 +/- 0.4 adducts/10(8) nucleotides and after repeated gavage of low doses of 10 and 1 mg/kg body wt (five times a week for 6 weeks) 6.2 +/- 0.2 and 2.0 +/- 0.4 adducts/10(8)nucleotides, but not in untreated animals nor in calf thymus DNA not treated with crotonaldehyde. In contrast to our results, Chung and co-workers found adducts in tissue of untreated Fischer 344 rats. This discrepancy could depend on the different methods used but also on differences in exposure of the animals via food or due to animal housing, etc.

Bovine serum albumin interacts with bacterial luciferase.

Bovine serum albumin (BSA) affects the amount of light obtained from bacterial luciferase by competing with luciferase for one of the luciferase substrates, the aldehyde. At low aldehyde concentrations BSA behaves as an inhibitor, but at high aldehyde concentrations BSA relieves substrate inhibition. BSA reversibly binds decanal with a Ksi = 3.36 mumol/l, approximately half the affinity of luciferase for decanal (KM = 1.5 mumol/l). BSA also increased the rate of intermediate II dark decay. The data suggest that this involves a direct protein-protein (BSA-luciferase) interaction.

An efficacy evaluation of a synergized glutaraldehyde-phenate solution in disinfecting respiratory therapy equipment contaminated during patient use.

Reusable, corrugated, expiratory limb ventilator tubing that had been in use for 24 hours, were randomly allocated to one of three groups: no treatment (N = 36); detergent wash (N = 83); or a detergent wash followed by a 10 minute immersion in a 1:16 dilution of synergized glutaraldehyde-phenate solution which was reused for 30 days. (Between 10 and 22 tubes were tested in each five day interval during this 30-day period.) Tubes were quantitatively and qualitatively cultured. There were significant differences in both the percent of contaminated tubes (no treatment = 92%, detergent wash = 72%, glutaraldehyde-phenate = 0 to 20%) and numbers of microorganisms per tube (no treatment = 3.2 x 10(6), detergent wash = 1.3 x 10(4), glutaraldehyde-phenate = 0 to 182) between groups. There was no apparent decrease in glutaraldehyde-phenate's efficacy throughout the 30-day reuse period, and in the final five days of the reuse period it was completely effective.

A collaborative study on a new quantitative suspension test, the in vitro test, for the evaluation of the bactericidal activity of chemical disinfectants.

In a collaborative study on a new quantitative suspension test for the evaluation of the bactericidal activity of chemical disinfectants, three laboratories performed the in vitro test on a phenol and an aldehyde standard in the critical use dilutions using Staphylococcus aureus and Pseudomonas aeruginosa as test organisms. The most striking finding was that the means of the germidical effect of one laboratory were significant lower than those of both others. Nevertheless the dispersion of the results did not differ among the laboratories. The differences could not be attributed to the subculture technique followed, nor to the daily inconstancy of the bacterial suspension resistance. The only feature that could explain the difference was the assessment of the microbiological work in itself. It should be stated, however, that the variance of the germicidal-effect values were rather low for this kind of microbiological work, so that differences between laboratories were significant even if the absolute values differed less than 1 unit.

Disinfection of anesthesia and respiratory therapy equipment with acid glutaraldehyde solution.

The dilution of acid glutaraldehyde solution and its effect on microbiological effectiveness were investigated using Sonacide and the Cidematic Decontamination System under normal use conditons at 18 hospitals over a 4-week period. The dilution of Sonacide was found to follow first-order kinetics and is described by the equation, ln C = ln Co-KT, where K is the apparent dilution-rate constant. The average dilution-rate constant under normal use conditions was 0.015/day. It takes an average of 47 days under normal hospital-use conditions to reduce its potency to half its original strength. The average glutaraldehyde concentration after 28 days' use was found to be approximately 66% of the initial concentration. The AOAC use-dilution test was employed to evaluate the microbiological effectiveness of the Sonacide samples collected weekly for four weeks. Results showed that all the Sonacide samples from 18 hospitals passed the AOAC use-dilution test for Pseudomonas aeruginosa (ATCC 15442). Based on this study, it is apparent that Sonacide can be used to disinfect various anesthesia and respiratory therapy equipment for up to 4 weeks in the Cidematic machine.