Analysis of phthalate esters contamination in drinking water samples

Phthalate esters are widely used as plasticizer. They can migrate from plastic materials to the environment. Exposure to some of these compounds may increase the risk of getting cancer. Phthalate esters: dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) were extracted simultaneously using a solid-phase extraction and compared with liquid-liquid extraction and analyzed by a gas chromatograph. The optimum condition method was successfully applied to the analysis of phthalate esters contamination in bottled drinking water samples. The concentration of DMP, DEP and DBP in drinking water samples were below allowable levels, while the DEHP concentration in three samples was found to be greater than the regulatory, maximum admissible concentration.Key words: Phthalate esters, drinking water, sample extraction, gas chromatography

Thai jute seed oil: a potential polyunsaturated fatty acid source

This study examined lipid and fatty acid compositions of different varieties of jute (Po-kra-jao, Corchorus olitorius L.) seed grown in Thailand. Four different jute seeds (Nonn-Soong, Keaw-Yai, Cuba and Khonkaen) harvested from northeastern Thailand were ground, their lipid was extracted with chloroform: methanol (2:1, v/v), and lipid composition was determined by Iatroscan (TLC/FID). Fatty acid composition was analyzed using GLC with standard methods. Triacylglycerol was a predominant lipid in jute seed oil, ranging from 70% to 74%, and other two minor components were phytosterol (12% to 28%) and diacylglycerol (0% to 9%). The ratio of saturates: monounsaturates: polyunsaturates, was approximately 2: 3: 4. Most predominant polyunsaturated fatty acid (PUFA) was linoleic acid (18:2n-6), accounting for 40-67% of total fatty acid. Nonn-Soong had the highest amount of PUFA (67.7%), followed by Khonkaen (44.53%), Keaw-Yai (41.14%), and Cuba (40.19%). Another PUFA found was α-linolenic acid (18:3n-3), accounting for about 1% of total fatty acid. The results indicated that jute seed oil was a potential edible PUFA source. The oils obtained from different kinds of jute seeds had significantly different lipid and fatty acid compositions

Interactions with Combined Chemical Cues Inform Harvester Ant Foragers' Decisions to Leave the Nest in Search of Food

Social insect colonies operate without central control or any global assessment of what needs to be done by workers. Colony organization arises from the responses of individuals to local cues. Red harvester ants (Pogonomyrmex barbatus) regulate foraging using interactions between returning and outgoing foragers. The rate at which foragers return with seeds, a measure of food availability, sets the rate at which outgoing foragers leave the nest on foraging trips. We used mimics to test whether outgoing foragers inside the nest respond to the odor of food, oleic acid, the odor of the forager itself, cuticular hydrocarbons, or a combination of both with increased foraging activity. We compared foraging activity, the rate at which foragers passed a line on a trail, before and after the addition of mimics. The combination of both odors, those of food and of foragers, is required to stimulate foraging. The addition of blank mimics, mimics coated with food odor alone, or mimics coated with forager odor alone did not increase foraging activity. We compared the rates at which foragers inside the nest interacted with other ants, blank mimics, and mimics coated with a combination of food and forager odor. Foragers inside the nest interacted more with mimics coated with combined forager/seed odors than with blank mimics, and these interactions had the same effect as those with other foragers. Outgoing foragers inside the nest entrance are stimulated to leave the nest in search of food by interacting with foragers returning with seeds. By using the combined odors of forager cuticular hydrocarbons and of seeds, the colony captures precise information, on the timescale of seconds, about the current availability of food