Distribution and Carcinogenicity of PCBs in Soil Contaminated with Transformer Oil in Selected Locations in Jos, Plateau State Nigeria

Soil from the vicinity of transformers installation in different locations in Jos, Plateau State was investigated for Polychlorinated Biphenyls (PCBs). The assessment was carried out for both total PCBs and congeners using Agilent 6975 GC-MS in ten different locations. The soil samples were extracted with 1:1 hexane- acetone in an ultrasonic bath, concentrated and cleaned with column chromatography using silica gel and hexane as eluting solvent. The result shows five locations were polluted with PCBs that exceed the maximum limit of 2.0mg/kg as permitted by the United States Toxic Substance Control Act (TSCA) with the following values NGS 1 (14.25), NGS 3 (4.47), NGS 6 (9.48), NGS 9 (8.21) and NGS 10 (5.05) while the others have NGS 2 (0.64), NGS 4 (1.85), NGS 5 (0.83), NGS 7 (0.95) in mg/kg respectively, NGS 8 value was below the instrument detection limit (0.0012mg/kg). The order for the total PCBs concentration in these selected locations are NGS 1 > NGS 6 > NGS 9 > NGS 10 > NGS 3 > NGS 4 > NGS 7 > NGS 5 > NGS 2. The carcinogenicity of the dioxin-like PCBs calculated as total toxicity equivalence concentration (TTEC) in these selected locations corresponds to NGS 1 (0.00001), NGS 2 (0.0000051), NGS 3 (0.0000054), NGS 4 (0.0000051), NGS 6 (0.0000063), NGS 7 (0.0000078), NGS 9 (0.0000051) and NGS 10 (0.0000051) respectively. The total cancer risk computed by addition of cancer risk due to ingestion, inhalation and dermal contact revealed that all the locations have very low to low cancer risk compared with the value recommended by the United State.

SIMULTANEOUS QUANTITATIVE 1H NMR ANALYSIS OF METHANOL, ETHANOL AND THEIR METABOLIC PRODUCTS IN HUMAN PLASMA: EARLY DIANOSIS AND MONITORING DURING TREATMENT OF ACUTE METHANOL POISONING IN VIETNAM

The 1H-NMR method for simultaneous quantification of methanol, ethanol and their metabolic products (formic acid and acetic acid) in human plasma was established. The effect of protein in plasma sample was removed by 25% trichloroacetic acid (TCA) with the ratio of TCA and plasma sample at 1/5 (v/v). The small amount of D2O (estimated 1/10 v/v) was chosen due to the effect of water signal was eliminated by using the advance water suppression with NOESY pulse sequence. The different analytical parameters such as linearity, precision, accuracy, and specificity, instrument detection limit (IDL) and instrument quantification limit (IQL) were validated. The instrument detection limit of four compounds in blank plasma varied from 0.68 (for methanol) to 2.88 mg/L (for formic acids). The average recoveries of concentration in dynamic ranges were found to be 96 to105%. The good linearity between concentration calculated by integrated signal and measured obtained by calibration curves confirmed that concentration of analytes in plasma can be directly determined from the 1H-NMR signal. The proposed method has been successfully applied for direct determination of five compounds in 9 patient’s plasma samples with the satisfactory results compared to GC/FID method. The analytical procedure can be useful for diagnosis and evaluation of treatment of methanol poisoning in Vietnamese hospitals.

Evaluation of the Analytical Conditions for the Determination of Chlorogenic Acid in Coffee Silverskin

Chlorogenic acid or 5-Caffeoylquinic acid is a polyphenolic component present in coffee and its by-products. Chlorogenic acid has been shown to exert biological properties, particularly in relation to glucose and lipid metabolism, including antibacterial, antioxidant, anti-inflammatory activities, among others. Due to its importance, it is necessary to evaluate the reliability of the analytical method for its determination in complex matrices such as food. In this work, different methods of chlorogenic acid extraction in coffee Silverskin were studied, as well as its quantification by HPLC. The results showed that the method of extraction with a mixture of methanol:water (3:1 v/v) in an ultrasonic bath, favored the recovery of chlorogenic acid with a recovery of 77.44%. The instrument detection limit for chlorogenic acid was 3.311 µg/mL and the quantification limit was 11.037 µg/mL. For coffee Silverskin, the concentration obtained of chlorogenic acid by the three extraction methods evaluated was in the range of 57 to 224 mg/kg of coffee silverskin (dry basis).

PENENTUAN KANDUNGAN RESIDU PESTISIDA DALAM TEH KOMERSIAL DI INDONESIA MENGGUNAKAN KROMATOGRAFI GAS DENGAN DETEKTOR PENANGKAP ELEKTRON

<p>Abstrak<br />Teh yang dipertimbangkan sebagai minuman sehat, seharusnya bebas dari unsur beracun seperti pestisida. Daun teh mengandung berbagai senyawa yang sangat kompleks dimana kandungan residu pestisida harus di bawah Batas Maksimum Resdiu (BMR) yang diijinkan. Oleh karena itu analisis residu pestisida dalam teh merupakan tantangan tersendiri bagi laboratorium pengujian. Penelitian ini bertujuan untuk menentukan kandungan residu pestisida dalam teh komersial di Indonesia, khususnya Jawa Barat dengan metoda pengujian yang telah dikembangkan oleh Laboratorium Kimia Analitik dan Standar, Pusat Peneliitian Kimia – LIPI. Residu pestisida yang dianalisis adalah α-endosulfan dan bifentrin. Instrument GC-ECD yang digunakan mempunyai kinerja sangat baik yang ditunjukkan dengan parameter verifikasi sangat memuaskan. Parameter verifikasi terdiri dari Instrumen detection limit (IDL) sebesar 0,034 dan 0,335 ng/g untuk -endosulfan dan bifentrin, linieritas dengan nilai regresi (r2) sebesar 0,9995 pada konsentrasi 1,42 – 128 ng/g untuk -endosulfan dan 0,9980 pada konsentrasi 1,43 – 129 ng/g untuk bifentrin, presisi waktu tambat (tR) dan luas puncak (area) sebesar 0,026 dan 4,012% untuk -endosulfan serta 0,031% dan 4,95% untuk bifentrin. Metoda pengujian yang digunakan sangat baik yang ditunjukkan dengan parameter validasi sangat memuaskan yang terdiri dari akurasi sebesar 78% dan 90% dengan presisi sebesar 19,04% dan 18,93% untuk -endosulfan dan bifentrin. Kisaran konsentrasi yang dapat diterima dengan ketidakpastian pengukuran sebesar  20% - 30% untuk -endosulfan dan bifentrin. Pada Internasional uji banding laboratoium, memberikan hasil memuaskan dengan nilai |Z| ≤ 2, baik untuk -endosulfan maupun bifentrin. Analisis residu pestisida dalam teh komersial untuk kedua senyawa tersebut, masih dibawah BMR yaitu 30 μg/g sehingga aman dikonsumsi.<br />Kata kunci : teh, pestisida, validasi metoda, GC-ECD.</p><p><br />Abstract<br />Tea is considered as a healthy beverage, should be free of toxic elements such as pesticides. Tea leaves contain various compounds that are highly complex and content of pesticide residues should be below Maximum Residu Limit (MRL). Therefore, the analysis of pesticide residues in tea is a challenge for laboratory testing. This study aims to determine the pesticide residues content in Indonesia’s commercial tea, especially West Java with the testing method which was developed by Analytical Chemistry and Standard Laboratory, Research Center for Chemistry – LIPI. Residue pesticides analyzed were α-endosulfan and bifenthrin. GC-ECD instrument used has excellent performance with the verification parameters shown very satisfactory. Parameter verification consists of Instrument detection limit (IDL) of 0.034 and 0.335 ng/g for -endosulfan and bifenthrin, linearity with regression values (r2) of 0.9995 at concentrations of 1.42 to 128 ng/g for -endosulfan and 0.9980 at concentrations of 1.43-129 ng/g for bifenthrin, precision retention time (tR) and peak (area) of 0.026 and 4.012% for -endosulfan and 0.031 and 4.95% for bifenthrin. The testing method used is very good as indicated by the very satisfactory validation parameters consisting of an accuracy of 78% and 90% with a precision of 19.04% and 18.93% for -endosulfan and bifenthrin. Acceptable concentration range with a uncertainty measurement of ± 20% - 30% for -endosulfan and bifenthrin. The international laboratory comparisons, gave satisfactory results with the value of | Z | ≤ 2, both for -endosulfan and bifenthrin. Analysis of pesticide residues in commercial tea of the two compounds was under MRL that is 30 μg/g, so safe for consumed.<br />Keywords: tea, pesticides, methods validation, GC-ECD.</p>

Ion Implanted Lateral p+-i-n+ Diodes on HPSI 4H-SiC

Square shaped annular lateral p+–i–n+ diodes on high purity semi-insulating (HPSI) 4H-SiC are fabricated by Al+ and P+ ion implantation to obtain anode and cathode regions, respectively. All the diodes have the same size central anode surrounded by an intrinsic region, which is surrounded by an annular cathode. Anode area and annular cathode width are fixed for all diodes, only the lateral length of the intrinsic region is varied. Post implantation annealing is performed at 1950 °C for 10 min. Static forward and reverse characteristics are measured in the temperature range of 30 - 290 °C. For all diodes, the reverse current is below the instrument detection limit of 10-14 A up to 100 °C at 200 V, the maximum reverse bias employed in this study. The reverse current increased up to low 108 A for 200 V reverse bias at 290 °C. Forward currents overlap at the low voltage region once they exceed the instrument detection limit at ~1.6 V and 30 °C. The forward currents follow almost identical exponential trend at all measured temperatures while the diode series resistance increase with increasing anode-cathode distance and decreased with increasing temperature for the given intrinsic region lateral length.

DISTRIBUTION OF HEAVY METALS IN NATUNA COASTAL WATERS

ABSTRACTThe study of Pb, Cd, Cu, Hg, and As and Fe in Natuna coastal waters, Riau Islands was conducted in November 2012. Water and sediment samples were collected from 35 stations by purposive sampling method and those heavy metals were analysed using Atomic Absorption Spectrophotometer, flame type (FAAS). The results showed that concentrations of total Pb, Cd, Cu, Hg, and As in surface water were below instrument detection limit (2 µg/L for Pb, Cd, and Cu; 0.02 µg/L for Hg and As). Moreover, the concentration of metal Fe in surface water was 0.021-0.054 mg/L. Concentrations of Pb and Cu in sediment were 0.05-22.67 mg/kg and 3.77-11.00 mg/kg, respectively, at which the highest concentrations were found near Binjai Estuary. Those concentrations were significantly below the standard levels set by CCME (2002) and ANZECC/ARMCANZ (2000). Concentration of Fe in sediment varied from 751.13-2309.12 mg/kg and showed similar spatial distribution to Cu-in-sediment. No standard level for Fe in waters was available. Generally, it can be concluded that Natuna coastal water was still uncontaminated. Keywords: heavy metals, iron metal, Natuna coastal waters.

Analytical Method for Dimethenamid-P in Selected Raw Agricultural Commodities by Gas Chromatography with Electron Capture Detection

A sensitive and simple method for the extraction and quantification of the herbicide dimethenamid-P from several raw agricultural commodities (RAC) is presented. The method provides sensitive and well-defined chromatography with baseline resolution in all matrixes tested. Homogenized samples were extracted with methanol–water, filtered, and then extracted with hexanes. A Florisil solid-phase extraction was then applied for the final cleanup. Sample separation and quantification were performed by gas chromatography with an electron capture detector. The instrument detection limit was 0.007 μg/mL, and the practical quantification limit was 0.003 μg/g (w/w) based on a 25 g sample. Recoveries for a series of fortified plant tissues ranged from 69 to 103%. The study demonstrated selective and sensitive recovery of dimethenamid-P from the RAC tested.