Simultaneous determination of pyrethroids from pesticide residues in porcine muscle and pasteurized milk using GC

The principal goal of this work was to develop an efficient method for the simultaneous determination of four pyrethroid (PYR) insecticides, cyfluthrin, cyhalothrin, cypermethrin, and deltamethrin, in porcine muscle and pasteurized milk using liquid–liquid extraction (LLE). Sample extraction was carried out with and without additional column cleanup procedures, and the final determination was made using GC with electron‐capture detector (ECD). The pesticide identity was confirmed using GC‐MS in the SIM mode. Since there were minor differences between the extraction procedures, extraction without the additional cleanup procedure was used throughout the work. The method was validated by fortifying blank samples with half, two, and four times the maximum residue limit (MRL) of each PYR. The average recoveries (n = 6) ranged from 83.5 to 99.2% and 82.9 to 109% in porcine muscle and pasteurized milk, respectively. The repeatability of measurements expressed as RSDs, was in the range of 1.7–11.9 and 1.5–10.3% in porcine muscle and pasteurized milk, respectively. The LODs ranged from 3.3 to 9 and 3 to 8.1 ppm, whereas the LOQs ranged from 10 to 27.4 and 9 to 24.6 ppm, in porcine muscle and pasteurized milk, respectively. The applicability of the method was demonstrated by analyzing real samples collected from major cities in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples.     

An orally administered microcapsule system for treating chronic renal failure patients

Ingestible adsorbents for the removal of uremic metabolites are being investigated as adjunctive therapy in the treatment of chronic uremia. In particular, a microcapsule product containing urease and zirconium phosphate (UZP) has been investigated for removing urea. A dog model, simulating chronic uremia, was developed to investigate: (1) the concentration of various nitrogenous metabolites (urea, creatinine, and uric acid) in the GI tract, (2) flux rates of H₂O and various nitrogenous metabolites in the GI tract, and (3) the efficacy of the microcapsule product. The results of these perfusion studies suggest that urea and creatinine can be removed from the GI tract via ingestible adsorbents. In addition, the model may be useful in investigating suspect uremic toxins, e.g., guanidinosuccinic acid (GSA). The reduction of blood urea nitrogen levels in the dog model when the animal was fed the microcapsule product was limited by the capacity of the zirconium phosphate to bind ammonium ion. Preliminary clinical studies with the microcapsule product indicate that it may be of potential adjunctive therapy in patients suffering from chronic renal failure.     

印刷线路板废弃物的热解及其产物分析

作为一种热固性复合材料 (ＳＭＣ) ,印刷线路板(ｐｒｉｎｔｅｄｃｉｒｃｕｉｔｂｏａｒｄｓ)广泛应用于自动控制、电子工业等多种工业领域。由于树脂在固化过程中与硬化剂加热成型时发生交联反应 ,使得树脂难于再熔化和溶解 ,热固性聚合物以前被认为是无法回收的。另一方面 ,ＳＭＣ包含大量玻璃纤维、ＣａＣＯ3 等无机组分 ,热值较低 ,焚烧也不适于处置此类物质。因此 ,填埋是目前大规模处置印刷线路板废弃物的主要方式。热解是一种适于回收塑料物质的技术 ,同样也适用于无法重铸的热固性复合材料[1] 。在热解过程中 ,有机聚合物分解成油状…     

Tagungsberichte XIX. Tagung der Generalkonferenz der IAEA

In der Zeit vom 22. bis 26. 9. 1975 fand in Wien die XIX. Tagung der Generalkonferenz der IAEA statt, an der auch eine vom Präsidenten des Staatlichen Amtes für Atomsicherheit und Strahlenschutz, Staatssekretär Prof. Dr. Sitzlack, geleitete Regierungsdelegation der DDR teilnahm. Auf der Konferenz waren 84 der nunmehr 109 Mitgliedsstaten der IAEA (als neue Mitglieder wurden die Vereinigte Republik Tansania, die Vereinigten Arabischen Emirate und Qatar aufgenommen) und 13 international Organisationen vertreten.     

Colored Gift Wrapping Papers as a Potential Source of Toxic Metals

Abstract

Sanitary land fills are the alternate to waste incineration in New Jersey. While industrial waste disposal is controlled, few restrictions apply to the disposal of domestic solid waste. Among the materials of concern from domestic sources are colored gift wrapping papers. Cadmium, chromium, copper, iron, manganese, molybdenum, nickel, lead and zinc were determined in some dozen and a half samples of gift wrapping paper by atomic absorption spectrometry after wet ashing and after simulated leaching. High levels of lead and chromium were found in many of the papers. The leachates showed correspondingly high levels of lead.     

Insight into the extraction and characterization of cellulose nanocrystals from date pits

This study aims to extract and characterize cellulose nanocrystals (CNCs) from date pits (DP), an agricultural solid waste. Two methods were used and optimized for the cellulose nanocrystals (CNCs) extraction, namely the mechanical stirrer method (CNCs₁) and the Soxhlet apparatus method (CNCs₂) in terms of chemical used, cost, and energy consumption. The results showed that scanning electron microscopy revealed the difference in the morphology as they exhibit rough surfaces with irregular morphologies due to the strong chemical treatments during the delignification and bleaching process. Moreover, transmission electron microscopy analysis for CNCs reveals the true modification that was made through sulfuric acid hydrolysis as it presents cellulose microfibrils with a packed structure. Fourier transform infrared proved that the CNCs were successfully extracted using the two methods since most of the lignin and hemicellulose components were removed. The crystallinity index of CNCs₁ and CNCs₂ was 69.99%, and 67.79%, respectively, and both presented a high yield of CNCs (≥10%). Ultimately, both techniques were successful at extracting CNCs. Based on their cost-effectiveness and time consumption, it was concluded that method 1 was less expensive than method 2 based on the breakdown of the cost of each step for CNCs production.     

Erfahrungen aus der Tätigkeit des Koordinierungsrates “Beseitigung radioaktiver Rückstände” der Ständigen Kommission Atomenergie des RGW

By means of the horizontal eleclrophoresis in carrier-free electrolyte solutions could be found conditions for a rapid and selective separation of mendelevium from the products of heavy ion reactions (^2l9Bk + ²²Ne) and the investigation of hydrolysis, reduction and complex formation. As non-isotopic tracers for experiments with Md(III) and Md(II) were used ^152/154Eu and ^87mSr.     

Kurtosis: a forgotten moment

The treatment of kurtosis in textbooks is both sparse and contradictory with applications rarely discussed. To address this, an easily understood definition of kurtosis is introduced and important applications are demonstrated. Two different approaches to teaching kurtosis are presented based on a financial application.     

Analysis of retinol, α‐tocopherol, 25‐hydroxyvitamin D2 and 25‐hydroxyvitamin D3 in plasma of patients with cardiovascular disease by HPLC–MS/MS method

Fat‐soluble vitamins play a pivotal role in the progression of atherosclerosis and the development of cardiovascular disease. Therefore, plasma monitoring of their concentrations may be useful in the diagnosis of these disorders as well as in the process of treatment. The study aimed to develop and validate an HPLC–MS/MS method for determination of retinol, α‐tocopherol, 25‐hydroxyvitamin D2 and 25‐hydroxyvitamin D3 in plasma of patients with cardiovascular disease. The analytes were separated on an HPLC Kinetex F5 column via gradient elution with water and methanol, both containing 0.1% (v/v) formic acid. Detection of the analytes was performed on a triple‐quadrupole MS with multiple reaction monitoring via electrospray ionization. The analytes were isolated from plasma samples with liquid–liquid extraction using hexane. Linearity of the analyte calibration curves was confirmed in the ranges 0.02–2 μg/mL for retinol, 0.5–20 μg/mL for α‐tocopherol, 5–100 ng/mL for 25‐hydroxyvitamin D2 and 2–100 ng/mL for 25‐hydroxyvitamin D3. Intra‐ and inter‐assay precision and accuracy of the method were satisfactory. Short‐ and long‐term stabilities of the analytes were determined. The HPLC‐MS/MS method was applied for the determination of the above fat‐soluble vitamin concentrations in patient plasma as potential markers of the cardiovascular disease progression.