جستجوی مقالات مرتبط با کلیدواژه "عناصر ضروری" در نشریات گروه "پزشکی"

Nowadays, tea is the most popular and frequently consumed beverages in the world after water. There are some beneficial trace elements in tea such as fluoride, caffeine and essential minerals, although there may be heavy metals in tea leaves which threat seriously human health. Therefore, the main objective of current study was to determine and monitor lead content in imported black and green tea leaves (Camellia sinensis L) and time of infusion and to compare the release of Pb from them by the time factor.

The mean content of lead in 450 brewed samples of green and black tea were determined in three different duration time of infusion (5, 10, and 15 minutes) by graphic atomic absorption spectrophotometer. Samples were prepared by wet digestion method due to international protocols AOAC by concentrated nitric and hydrochloric acid. Analysis of variance (ANOVA) was employed to detect significances among samples from different time of infusion in samples.

The results showed that in the brew of dry black and green tea samples, the amount of lead was less than the allowable limit of the dry tea sample (1ppm). Also the amount in the brewed tea in 15 minutes was higher than 10 minutes and it was higher than 5 minutes.

The amount of lead in the brewed tea was lower than in the dry samples. The best time to brew tea is 5 minutes, when the amount of lead is the lowest and the organoleptic properties have the best conditions in terms of flavor.

Background and Cereals are the most important components of a healthy diet. Rice is one of the most common consumed grains in the world and a staple food of people in everyday meals. This study aimed at introducing a novel analytical approach in investigation of harmful metals and necessary elements in some types of Iranian rice by using Laser Induced Breakdown Spectroscopy (LIBS) method. Six types of consumed rice produced in different parts of the country have been collected from the market in 2013. All types of rice have been analyzed for seven times using LIBSCAN100 system and then spectra recorded have been analyzed by Plasus Specieline software. In this study، necessary elements and harmful metals have been analyzed in all samples. The average concentrations of zinc، phosphorus، iron، potassium، calcium، fluorine، chromium (III)، and magnesium were 93. 660mg/kg، 87. 666mg/kg، 348mg/kg، 379. 166mg/kg، 343. 66 mg/kg، 22mg/kg، 24. 848mg/kg 1071. 833mg/kg، respectively. This average content for harmful metals were 6. 095mg/kg for lead، 0. 773mg/kg for mercury، 0. 963mg/kg for nickel، 2. 391mg/kg for chromium (VI)، and 0. 940mg/kg for arsenic. No samples were found with cadmium. The results indicate that، the concentration of magnesium was higher in necessary elements and that Isfahan Lenjan rice contained higher content of necessary elements. Chromium (VI) was the most common harmful metal among all samples. Furthermore، the local Tarom rice was found to be the safest in all samples. Laser Induced Breakdown Spectroscopy technique could be used as a fast، nondestructive، multi elemental analyzer that does not need initial preparation.