trace analysis of oxytetracycline and tetracycline residues in pasteurized milk supplied in Tehran: a one-year study [April 2011-March 2012]

Tetracyclines [TCs] are broad-spectrum antibiotics that are widely used in veterinary medicine. The presence of TCs residues in milk is a public health concern all over the world. This study aimed to determine TCs residuals in pasteurized milk marketed by some dairy companies in Tehran from April 2011 to March 2012. 432 pasteurized milk samples were purchased from supermarkets supplying the milk products of 12 major dairy companies in Tehran [3 samples from each company every month], and they were stored at -20 0C until analysis. Oxytetracycline [OTC] and Tetracycline [TC] residues in each sample were extracted by a liquid - liquid phase procedure and quantitated using a high performance liquid chromatographic [HPLC] method. Chromatographic conditions included a mobile phase as oxalic acid buffer- acetonitril [80: 20] with a flow rate of 1mL/min and UVdetection at 355 nm. TCs residuals in most milk samples were lower than 100 ppb, maximum residue level [MRL]; however, in seven samples [1.62%] the total residues of OTC and TC were more than MRL. In the latter milk samples, the median total TCs residue was 625 ppb, ranging between 274 and 1270 ppb. Because of the presence of TC residues above the MRL level in a limited number of milk samples, it is concluded that more studies and supervision of health authorities are needed in this field

[Determination of corrosion and sedimentation potential in drinking water distribution system of Khorramabad city by corrosion indices and weight loss method]

According to the standard, drinking water must not be corrosive. Corrosive water solve primery materials of pipes, joints and valves in municipal water distribution systems and home plumbing systems and cause a lot of health, aesthetic and economic problems in water distribution systems. Thus, determination of corrosion potential of drinking water using methods which are feasible and reliable is necessary, and corrosion should be controlled in drinking water for water sanitation and health promotion among citizens. This research was carried out to determine water corrosivity or sedimentation potential in Khorramabad city, using corrosion indices. In this project 50 points as samples in two stages in the Summer and Autumn seasons were determined, and amount of corrosion indices, including Langelier Indice, Ryzener indice, Aggressive indice and Pokurious indice, corrosivity and temperature, calcium hardness, alkalinity, total dissolved solid and PH were calculated two times within a 3-month interval, then the data obtained from results were analyzed using SPSS software and statistical tests. Results of corrosion indices show that drinking water of Khorramabad is in equilibrium condition and has tendency to corrosion. Calculated corrosion indices are as follows: Langelier [-0.157], Ryzener [7.86], Aggressive [11.626], and Pokurious indice [7.65]. Statistical tests of Pearson and Spearman correlation coefficient don't indicate significant relationship between quality parameters with corrosion indices. Results of corrosion indices showed that drinking water of Khorramabad is inclined to corrosion