The effect of glufosinate ammonium in three different textured soil types under Malaysian tropical environment

Glufosinate ammonium is a broad spectrum, non-selective, contact and organophosphate herbicide which is commonly used in Malaysian oil palm plantations. Research area was one of the oil palm growing areas of Malaysia is located adjacent to the Tasik Chini, Pahang. Farmers use this herbicide to control several types of unwanted plants which could compete with the oil palm for nutrients. Rain water and the sprayed solution are easily adsorbed by soil particles. The glufosinate ammonium sorption was determined by the batch equilibrium technique. The collected soil samples (0-50 cm depth) divided into five groups at 10 cm depth intervals. Glufosinate ammonium adsorption coefficients were correlated with the soil pH, organic matter (OM), clay content, and cation exchange capacity (CEC). Series of glufosinate ammonium standard were as 0.01, 0.1, 0.25, 0.5, 1, 3, 5, and 10 μm/mL. The Linear and Freundlich equations were fitted for obtaining the adsorption and desorption isotherms. The result of the analyses showed that adsorption of glufosinate ammonium was correlated to the clay content. The clay fraction of the soil is the main absorbent of the glufosinate ammonium. Desorption from the soil was indicated by the high binding strength of the adsorbed glufosinate ammonium

Dissipation of chlorpyrifos in a Malaysian agricultural soil: a comparison between a field experiment and simulation by the VARLEACH and PERSIST models

A comparison of the dissipation of chlorpyrifos in a Malaysian agricultural soil was undertaken using data from a field experiment and simulation by the PERSIST model. The study was carried out at an oil palm estate located close to the Kuala Lumpur International Airport (KLIA), Sepang, Selangor (for field experiment). The plots were treated with chlorpyrifos at the manufacturer’s recommended dosage. Soil samples were collected according to the sampling schedule at intervals of 0, 1, 3, 7, 14, 21, 30, 60 and 90 days. Residues of chlorpyrifos in soil from the field trial were analyzed in the laboratory. Simulation of chlorpyrifos leaching and persistency was done using two computer-run software VARLEACH and PERSIST. Generally, predicted data for chlorpyrifos residue obtained using the VARLEACH and PERSIST models was found to be well matched with the observed data from the field trial. The PERSIST Prediction for chlorpyrifos residue in soils planted with oil palm trees was found to be accurate and conformed to the results observed in the field trial

Triclopyr 3, 5, 6-trichloro-2-pyridinyl clean-up procedure from soil, sediment and water samples using SPE-HPLC-VWD

Triclopyr is a post emergence herbicide used to control woody plants. After application, the excess amount will enter the soil and water bodies and it is present in ppb level thus making extraction very difficult. The extraction of triclopyr 3, 5, 6-trichloro-2-pyridinyl residue from soil, sediment and water samples under different solid phase extraction (SPE) sorbent efficiency was studied for better recovery. Four different SPE sorbents i.e.: Oasis HLB, Water Sep-Pak, Cromabond (cation/anion PS-H+ /OH-), Isolute ENV+ and a series of solvent i.e. potassium dihydrogen phosphate (KH2PO4 0.1M), sodium hydroxide (NaOH 0.2M), potassium hydroxide (KOH 0.5 & 0.6M), ammonium acetate, methanol and water were used as extraction solution. Sample clean-up performance was evaluated using high performance liquid chromatography (HPLC, Agilent 1220 infinity LC) with variable wavelength detector (VWD) 290 nm. Cromabond®H+/OHcolumn with 0.6 M KOH was the most suitable for the clean-up in view of the overall feasibility of the analysis. The highest recovery was 89.32%

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

The persistence of deltamethrin in Malaysian agricultural soils

Studies on the persistence and dissipation of deltamethrin (C22H19Br2NO3) in two types of soil, namely peat and silty clay were conducted under laboratory conditions. The analysis was done using a gas chromatography (GC) equipped with an electron capture detector (ECD). The dissipation rate of deltamethrin was faster in silty clay soil than in peat soil at 25°C. When the temperature was increased from 25 to 35°C, the half-life of deltamethrin decreased by 32.53% in peat soil and 22.9% in the silty clay soil in the presence of light. When the same experiment was conducted in the dark, the decrease in the half-life of deltamethrin was 27.9% in peat soil and 22.5% in silty clay soil. When the soil moisture content was increased from 40 to 60%, the half-life of deltamethrin decreased by 50.7 and 19.75% in peat soil and silty clay soil, respectively. A significant degradation rate of deltamethrin was observed in non-autoclaved soil compared with that in autoclaved soil where the half-life was reduced by 76.05% in peat soil and 59.21% in silty clay soil. The results showed that the degradation rate of deltamethrin in soil had a direct relationship with the microbial activity in the soil

Troubleshooting and maintenance of high-performance liquid chromatography during herbicide analysis: an overview

Glufosinate ammonium or ammonium salt (ammonium-(2RS)-2-amino-4- (methylphosphinato) butyric acid; C5 H15N2 O4 P) is a commonly used polar herbicide in Malaysia and present in a variety of environmental waters at the sub-ppb level. Thus, glufosinate ammonium is analyzed in soil and water using high-performance liquid chromatography (HPLC), which is a complex yet the most powerful analysis tool. HPLC is tremendously sensitive and highly automated and HPLC instrumentation and machinery have improved over the years. However, typical problems are still encountered. HPLC users and advanced learners require help in identifying, separating and correcting typical problems. All HPLC systems consist of similar basic components. Although it is a modular system, trouble can occur in each component and change the overall performance. Resolving these problems may be expensive. This review describes the different aspects of HPLC, particularly troubleshooting, common problems and easy guidelines for maintenance

Degradation of triazine-2-14C metsulfuron–methyl in soil from an oil palm plantation

<p>Materials and Methods</p> <p>Chemicals</p> <p>The herbicide selected for the study was metsulfuron-methyl. The purity of the technical sample used as the analytical standard and for various laboratory studies was approximately 99%. 14C-radiolabelled metsulfuron-methyl (methyl 2-[[[[(4-methoxy-6-methyl-1, 3, 5-triazin-2-yl) amino] carbonyl] amino] sulfonyl] benzoate) was synthesised at DuPont, New England Nuclear (NEN) Research products, Boston MA. It was labelled uniformly at the 2-carbon in the triazine ring [triazine-2-14C] and phenyl ring [phenyl-14C] and has specific activity of 1.85 MBq mg-1 (49.87 µCimg-1) and 1.42 MBq mg-1 (38.28 μCimg-1), respectively. The 14C-labelled compound used had radiochemical purity higher than 99%, as determined by high performance liquid chromatography (HPLC). Unlabelled reference standards of the test substance and expected degradation products were synthesised at the DuPont Agricultural Products, E.I. Du Pont de Nemours and Company (Wilmington, DE). All organic solvents and water used in the study were of HPLC grade. All other chemicals were of the deionized grade. The radioactivity in the samples was determined by LSC in scintillation fluid. The potassium hydroxide and ethylene glycol trap solution was used to trap 14CO2 and organic volatiles released during combustion.</p> <p>Soil</p> <p>Soil samples (Bernam Series) were collected from the top 15 cm of the soil at the field trial site at Sungai Buloh Estate. Soil characteristics were determined at the Harris Laboratories, Inc. (Lincoln, NE), and are provided in Table 1. The fresh soil was sieved through a 2 mm sieve and used immediately for the study. Soil samples taken from biometer flasks identical to those used in the degradation studies were evaluated for total bacterial counts so as to ascertain the effect of the closed system of the flask on the microbial population of the soils. The soil was sampled at day 0 (immediately after treatment), and at 30 and 60 days. The plating process commenced with the measurement of 23.0 g of nutrient agar (from Difco laboratories, Detroit MI 48232-7058, USA) consisting of Bacto beef extract (3 g), Bacto peptone (5 g) and Bacto agar (15 g) to which was added to 800 mL of sterilised water. The mixture was heated on a hot plate magnetic stirrer until uniform solubility was achieved and the final solution was made up to 1 litre with sterilised water. An autoclave (All American Electric Pressure Steam Sterilizer Model No 25X) was used to sterilise the agar solution (at 15 kPa for 15 minutes, temperature 121ºC). The agar solution was left to cool at room temperature soon after autoclaving, and while still warm, plating was done. Agar plating was carried out using 25 mL of agar solution per plate, left overnight to solidify. Soil samples (10 g each) collected at specified intervals of time, were added to conical flasks each containing 90 mL of sterilised water and shaken on a rotary shaker (Stuart Flask Shaker; Stuart Scientific Co. Ltd. England) for 1 h. This was followed by serial dilution of 10 fold steps and the appropriate dilutions poured out onto nutrient agar plates and incubated for a duration of 24 – 48 h at 30 ºC, before counting of the colonies was carried out. Results of microbial colonies counted were expressed in colony forming units (CFU).</p> <p>Table 1. Soil characterization.</p> <p>Soil Property</p> <p>Unit</p> <p>Result</p> <p>Texture1</p> <p>NA2</p> <p>Clay</p> <p>Sand</p> <p>%</p> <p>27.6</p> <p>Silt</p> <p>%</p> <p>27.2</p> <p>Clay</p> <p>%</p> <p>45.2</p> <p>pH (Water)</p> <p>NA</p> <p>4.5</p> <p>pH (0.01 M CaCl2)</p> <p>NA</p> <p>4</p> <p>Organic Matter (Ashing)</p> <p>%</p> <p>4.6</p> <p>Organic Matter (Walkley-Black)</p> <p>%</p> <p>4.3</p> <p>Organic Carbon (Walkley-Black)</p> <p>%</p> <p>2.4</p> <p>Bulk Density</p> <p>g/cm3</p> <p>0.92</p> <p>Moisture Holding Capacity (0 Bar) 3</p> <p>%</p> <p>65.2</p> <p>Moisture Holding Capacity (0.1 Bar)</p> <p>%</p> <p>46.5</p> <p>Moisture Holding Capacity (1/3 Bar)</p> <p>%</p> <p>45.0</p> <p>Moisture Holding Capacity (15 Bar)</p> <p>%</p> <p>23.3</p> <p>Cation Exchange Capacity</p> <p>meq/100 g</p> <p>25.6</p> <p>Nitrogen, Total</p> <p>mg/kg</p> <p>2220.00</p> <p>Phosphorus (Bray)</p> <p>mg/kg</p> <p>96</p> <p>Phosphorus (Olsen)</p> <p>mg/kg</p> <p>39</p> <p>Potassium</p> <p>mg/kg</p> <p>313</p> <p>Magnesium</p> <p>mg/kg</p> <p>61</p> <p>Calcium</p> <p>mg/kg</p> <p>763</p> <p>Sodium</p> <p>mg/kg</p> <p>22</p> <p>Soluble Salts</p> <p>mmhocm-1</p> <p>0.23</p> <p>USDA system (Sand: 2 mm-50 mm, Silt 50-2 mm, Clay: <2 mm)NA=Not Applicable% of dry weight</p> <p>Experimental Setup</p> <p>Samples of the Bernam Series soil was collected from the field experimental site at Sungai Buloh Estate. The soils samples were passed through a 2 mm sieve and used immediately. Each soil sample (100 g) was placed in a sample bottle, connected to the trap bottle. The trap bottle was connected to an ethylene glycol (25 mL) bottle to trap any organic volatiles. Lastly the ethylene glycol bottle was connected to a 0.1 M KOH (25 mL) bottle to trap 14CO2 evolved as a result of microbial activity (Fig. 1). The flask was corked with a rubber stopper. The soil was maintained at the water holding capacity of 50% throughout the experiment. This was achieved by periodically weighing the flask and by the addition of water as required. The experiment was conducted in a “controlled environment” chamber with the temperature maintained at 30ºC (±1ºC) and the humidity at 80% (±2%), in total darkness. The experiment was replicated three times.</p> <p>For the sterile system, the same number of flasks was prepared as described above except that each flask that contained 100 g dry weight equivalent (of the moist soil) which was autoclaved at 15 kPa and 120ºC for 1 hour on four separate days to destroy the microorganisms. The Market Forge Sterilmatic autoclave Model STM-EL was used to sterilise the soil. The sterile test system was connected to a volatile trapping system as described above, with the addition of a sterile Gelman ACRO 50 PTFE 0.2 μm filter inserted before the test system flask, to prevent microbial contamination.</p> <p>Treatments</p> <p>Triazine Ring [triazine-2-14C] Metsulfuron-methyl</p> <p>The primary stock solution of 1503 μg/mL (specific activity, 49.87 μCi/mg) was prepared by mixing 15.03 mg of the neat material (99% purity) with 10 mL of sterilised water where the pH was adjusted to a pH of 7. This primary stock solution was stored frozen when not in use. A 15.03 μg/mL secondary stock solution (specific activity, 49.87 μCi/mg) was prepared by diluting a 1 mL aliquot of the primary stock solution (1503 ppm) to a final volume of 100 mL in sterile deionized water. A 93 μL aliquot of this solution was mixed with 100 g of soil in each designated vessel to produce a concentration in the soil of approximately 1.4 ppm. This concentration allowed for adequate detection levels of the parent material and its metabolites.</p> <p>Reference Standard Solutions</p> <p>Solutions of metsulfuron-methyl and reference chemicals were prepared by dissolving 5 mg of the mixture in 5 mL of water: acetonitrile (3:2, v: v). Dilutions and mixtures of the standard solution were prepared in reagent water prior to the HPLC analysis. Mixtures of the following standard solutions were prepared to evaluate the HPLC resolution of degradation from the triazine radiolabelled test substance and for the purpose of performing chromatography: IN-B5528, IN-A4098, IN-D5803, IN-B5067, IN-F5438, IN-MU717, and DPX-T6373.</p> <p>Sample Collection and Handling</p> <p>Sampling was conducted at various intervals by taking the three replicate bio meter flasks at 0 (immediately after treatment), 1, 3, 7, 10, 14, 21, 30, 45, and 60 days after treatment (DAT). One mL aliquots (in triplicates) of 0.1 M KOH and ethylene glycol solutions used to trap 14CO2 and organic volatiles were sampled at each of the specified intervals. The solutions were combined with the scintillation fluid and analysed for total radioactivity by the Liquid Scintillation Counter (LSC).</p> <p>Extraction of Soil Radioactivity</p> <p>At each sampling time, two flasks (one from each of the two 14C metsulfuron-methyl treatments) were taken for the extraction process. Step 1 - The soil in each test flask was mixed with 100 mL of acetonitrile: 2 M ammonium carbonate (9:1, v: v) and shaken for 1 hour on a platform shaker at room temperature (23ºC). The solution was centrifuged at approximately 2500 rpm for 15 minutes. The supernatant was decanted to a graduated cylinder. The extraction process was conducted 3 times, and the extracts pooled; 1 mL aliquots were analysed in triplicate by LSC. The recovery study was conducted by spiking a known amount of two 14C metsulfuron-methyl on the soil sample following the same procedure. The sample was left for 1 hour before it was analysed by LSC.</p> <p>After step 1 extractions were done, the bound residue (%) in the extracted soil was estimated from the equation:</p> <p>If the estimated bound residue was >10% of the applied radioactive metsulfuron-methyl, extraction step 2 was done. Step 2 - After the first extraction, extraction of the remaining residues from the soil samples were done using 100 mL of CH2Cl2: methanol: 2 M ammonium carbonate (3:4:1, v: v: v), followed and by shaking for 1 hour at room temperature (23ºC). The extraction process was conducted 3 times, the extracts pooled, and 1 mL aliquots were analysed in triplicate by LSC. The LSC aliquots must be withdraw in the homogenous phase. After step 2 was completed, the step 1 and step 2 extracts were pooled. The extracts were concentrated by vacuum rotary evaporation and re-dissolved in water. Aliquots were analysed in triplicate by LSC and an aliquot was removed and analysed by HPLC. The extracts were stored in a freezer at - 4ºC.</p> <p>Analysis of Soil Extracts</p> <p>Soil extracts were analysed using a HPLC equipped with both a UV - detector and an on-line radio-chemical detector (Ramona, Raytest Inc). The HPLC method 1 used the Supelco Discovery column (250 x 4.6 mm, 5 μm) and a gradient with mobile phase A, a phosphate buffer H2O (pH ± 7), and B, methanol (from 0 to 3.5 min, 100 % B; at 19 min, 90% B; at 19.5 to 29.5 min, 80% B; at 30 to 37 min, 65% B; at 40 to 42 min; 0% B and 45 min, 100% B). The HPLC method 2 used a PRP-1 column (305 x 7.0 mm, 10 μm) with the same mobile phase as the HPLC method 1 but with a different gradient (from 0 to 3 min, 10% B; at 10 min, 20% B; at 20 min, 40% B; at 30 min, 90% B at 35 min, 100% B). The mobile phase flow rate was 1.5 mL min-1 for both methods. The oven and injector temperature readings were set at 35ºC. The HPLC method 1 was used for all the sample analyses and HPLC method 2 was used for confirmatory analyses. The standard mix (a mixture of available standards) was used to verify that the above HPLC conditions adequately separated metsulfuron-methyl from its expected metabolites, and also to confirm the retention times of the standards used during the course of the study. Aliquots of concentrated extracts of 250 μL were injected onto the column, and the elution of radioactivity was monitored and quantitated by fraction collection and LSC.</p> <p>Determination of Soil Un-extractable residues</p> <p>Post-extracted soil samples were air-dried in the laboratory hood. When dry, the samples were homogenized and weighed. Aliquots in triplicate were combusted using the Harvey biological oxidizer (Harvey Instrument Inc., model OX 500). The 14CO2 released from the combustion process was trapped in 15 mL of 14C-cocktail scintillation fluid and radioactivity was measured from the LSC analysis.</p> <p>Determination of DT50 and DT90</p> <p>The first-order model was used to estimate the DT50 (the time required for 50% of the applied chemical to degrade) and DT90 (the time required for 90% of applied chemical to degrade) values. The First-order model equation used is as [15-16]:</p> <p>Where,</p> <p>C0: Initial concentration (mg/kg)</p> <p>C : Concentration at time t (mg/kg)</p> <p>K : Degradation rate constant</p

Characterization of optically stimulated luminescence for assessment of breast doses in mammography screening

Landauer optically stimulated luminescence (OSL) technology nanoDot dosimeters (OSLDs) are characterized for use in mammography screening at various tube voltages, mAs values and target/filter combinations. The average glandular dose (AGD) for a 50-mm breast, based on the representative compressed breast thickness of a 45-mm polymethyl methacrylate (PMMA) phantom, is assessed using OSLDs with different beam conditions. Further, the linearity of the OSLD response is measured and angular dependence tests are performed for various tube potentials, mAs and target/filter combinations. The breast-absorbed doses are measured at various depths for a 32-kVp X-ray beam at 100 mAs, with a Mo/Rh target/filter combination. The measured incident air kerma values at different lateral positions exhibit a maximum deviation of 6%, and the average relative response of the OSLDs at the reference point (center) with respect to various lateral positions is found to be 1.001 ± 0.09%. The calculated AGD values are in the 1.3 ± 0.1−3.5 ± 0.2 mGy range, depending on the tube potential, tube loading and target/filter combinations. An exposure setup featuring the auto-exposure control (AEC) mode, 28 kVp, 73.8 mAs, and a Mo/Rh target/filter combination may be preferred for mammography screening for a compressed breast thickness of 45 mm