The application of novel extraction and analytical techniques in forensic toxicology

The aim of this study was to investigate new methods of analysis which might be applied to forensic toxicology problems including those resulting from pesticides, particularly the quaternary ammonium herbicide group, and from drugs, particularly the benzodiazepine group. In the first part of this study, an efficient method for the determination of quaternary ammonium (QA) compounds (pesticides and drugs) in human whole blood was developed. The second part of this study concerned the development of a novel sorbents for solid phase extraction using molecularly imprinted polymers (MIPs). The approach adopted was initially to synthesise a known MIP using diazepam as template then to prepare novel MIPs using other benzodiazepines and analogues of QA compounds as templates. In the first of these stages, an anti-diazepam MIP was synthesized using methacrylate acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-liner and was then ground and prepared for use as an SPE sorbent by packing it into SPE cartridges. These cartridges were used to clean up extracts of diazepam and other benzodiazepine drugs made from hair samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. The MISPE method was also found to be applicable to the analysis of diazepam metabolites and other benzodiazepine drugs in addition to diazepam itself. The application of the extraction method to post-mortem hair samples yielded results that were in good agreement with ELISA data (from blood samples) and data arising from the analysis of the same blood samples using a validated in-house SPE-LC-MS-MS method. The MISPE procedure was also compared with a conventional SPE method for analysis of benzodiazepines in hair samples. The results from MISPE protocol showed better selectivity, specificity and accuracy toward diazepam (template molecule) and other benzodiazepines that display a similar resemblance to diazepam in terms of molecular structure. The MISPE procedure was found to be simpler and to offer cleaner extracts compared to a conventional SPE method

Rapid extraction of bisphenol A by dispersive liquid-liquid microextraction based on solidification of floating organic

Bisphenol A is an endocrine disruptor with widespread applications, especially in the production of polycarbonate and epoxy resins. Dispersive liquid-liquid microextraction based on solidification of floating organic technique has been developed for the extraction of bisphenol A from water and soft drink. The 1-undecanol has been applied as the extraction solvent because of its low density and melting point and high affinity to the analyte. The technique offered rapid and simple analysis as the 1-undecanol was homogeneously dispersed in the sample solution to speed the extraction and the collection of extraction solvent was simplified by centrifugation, cooling and melting steps

LYSOZYME TRANSMISSION THROUGH POLYMERIC BASED ULTRAFILTRATION MEMBRANE: EFFECT OF PH AND IONIC STRENGTH

ABSTRACT Fractionation and purification of complex protein mixture has becomes a great interest and has attracted a considerable amount of attention in recent years. This study aimed is to demonstrate the factors influencing the lysozyme separation through polyethersulfone ultrafiltration (UF) membrane. Asymmetric UF membrane with 15% polymer composition (UF15) was developed via phase inversion technique. Membrane was characterized in term of morphology, membrane surface charge and molecular weight cut-off to ensure its suitability for lysozyme separation. Effect of pH on the transmission of lysozyme through the UF15 membrane has been examined at different pH (5, 7, 9, 11 and 13) and ionic strength (0.1M, 0.2M and 0.3M). Results displayed that at optimum pressure 3 bars, permeation with pH 9 and 0.1M ionic strength of feed solution obtained the optimum flux and lysozyme transmission for about 36.6 x 10 -5 m 3 /m 2 and 92.9%, respectively. This study has proved that pH and ionic strength were found to be greatly affected the lysozyme transmission and promoted the lysozyme separation to a significant degree

Adsorption of formulated chlorpyrifos on selected agricultural soils of Terengganu

In this study, the adsorption of commercially formulated chlorpyrifos (trade name Kensban®, 20% a.i.) in three soil samples (0-25cm depths) collected from vegetable farms in the state of Terengganu, Malaysia has been investigated using a batch technique. Analysis of the insecticide was carried out using gas chromatography equipped with nitrogen and phosphorus detector. Result indicated that, soils contained higher organic matter and clay content exhibited a much stronger adsorption affinity for the insecticide. In addition, soil pH was also observed to play a role in influencing the adsorption affinity of this insecticide where a higher adsorption was observed for soils with lower pH values. Results from this study clearly showed that, in agreement with previously reported studies, soil properties particularly organic matter content, clay content and pH play an important role in controlling the sorption behaviour of chlorpyrifos insecticide. However, it must be conceded that the measured adsorption in this study might also be influenced by a number of processes occurred in the soil, such as complex interaction between chlorpyrifos, solvent, emulsifier, water and the soil sorption sites since the applied chlorpyrifos was a commercial formulation

Hydrolysis of chlorpyrifos in aqueous solutions at different temperatures and pH. The Malaysian

Abstrak Hidrolisis klorpirifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate) telah dikaji dalam media akues pada suhu dan keadaan pH yang berbeza. Pemalar kadar dan jangka hayat separa yang diperolehi menunjukkan bahawa klorpirifos lebih stabil dalam keadaan berasid. Kadar degradasi meningkat apabila nilai pH bertambah. Suhu juga mempengaruhi kadar hidrolisis. Hidrolisis klorpirifos dalam air mematuhi tindak balas tertib pertama. Jangka hayat separa klorpirifos dalam larutan akues adalah pendek (di antara 4.57 hingga 14.0 hari), dan ianya bergantung pada kepekatan asal klorpirifos dan jenis larutan akues. Kadar degradasi adalah perlahan dalam larutan 0.02M CaCl 2 dengan kepekatan asal klorpirifos yang tinggi. Perbandingan antara kadar hidrolisis dalam laruatan air steril dan tidak steril tidak menunjukkan peranan biodegradasi yang ketara dalam air tidak disteril. Keputusan ini menunjukkan bahawa parameter pH sahaja tidak mencukupi untuk menjangkakan kadar hidrolisis klorpirifos. Katakunci: Klorpirifos, hidrolisis, pestisid organofosforus Abstract The hydrolysis of chlorpyrifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate) was investigated in buffered aqueous media at different temperature and pH conditions. Rate constants and half-life studies revealed that chlorpyrifos was relatively stable in acidic medium. The rate of degradation increased as the pH increased. Temperature showed a significant effect on the rate of hydrolysis. The hydrolysis of chlorpyrifos in water follows first-order kinetics. The half-life of chlorpyrifos in aqueous solutions was short (half-lives ranged from 4.57 to 14.0 days), depending on the initial concentration of chlorpyrifos and the type of the aqueous solutions. The rate of degradation was slower in the 0.02M CaCl 2 solution containing higher initial concentration of chlorpyrifos. Comparison between hydrolysis rate of chlorpyrifos in sterilized and non-sterilized water did not showed significant contribution of biodegradation component. These results indicate that pH alone cannot be used as a single parameter to predict hydrolysis of chlorpyrifos

Penilaian kesan antropogenik terhadap kualiti air di Tanah Bencah Setiu, Terengganu

Satu kajian telah dijalankan untuk menentukan taburan nutrien, klorofil-a dan sifat fizikal air di Tanah Bencah Setiu dari bulan Mei-Oktober 2001. Sepuluh stesen pensampelan telah dipilih untuk mewakili kawasan-kawasan yang berlainan di kawasan kajian. Analisis nutrien terlarut dan klorofil-a dijalankan berdasarkan kaedah kolorimetrik manakala parameter fizikal diukur secara in situ. Hasil kajian menunjukkan bahawa pH mempunyai nilai antara 5.15-8.03, oksigen terlarut 4.89-6.85 mg/L, permintaan oksigen biokimia 0.04-1.80 mg/L dan jumlah pepejal terampai 1.3-19.7 mg/L. Kepekatan ortofosfat, jumlah fosfat terlarut, nitrat, ammonia, jumlah nitrogen terlarut dan klorofil-a adalah masing-­masing dalam julat 0.19-2.85 μg P/L, 1.06-25.81 μg P/L, 1.48-89.66 μg N/L, 6.0-125.7 μg N/L, 122.50-432.34 μg N/L dan 0.03-4.32 mg/L. Disamping itu, keputusan yang didapati turut mencadangkan kemungkinan wujudnya hubungan antara kepelbagaian aktiviti guna tanah dan kemerosotan kualiti air di kawasan tanal: bencah

Green and efficient preconcentration of calcium channel blocker drugs in water using effervescence powder in syringe-assisted deep eutectic solvent dispersive liquid-liquid microextraction

Efficient preconcentration techniques are crucial for the analysis of calcium channel blocker drugs such as amlodipine and nifedipine, commonly used for hypertension and heart diseases. This study optimized the preconcentration conditions using CO2 effervescence powder assisted deep eutectic solvent dispersive liquid-liquid microextraction (EP-DLLME). A central composite design with 30 experiments was employed to determine the effects of extraction solvent volume, effervescence powder mass, water sample volume, and pH water. The optimized conditions for EP-DLLME were determined as follows: 500-μL of extraction solvent, 25-mL of water sample, 5 mg of effervescence powder, and pH 8. High-performance liquid chromatography (HPLC) coupled with a diode array detector was utilized for subsequent analysis. The method exhibited good linearity (r2 = 0.996) and low limits of detection and quantification: 1.73 ng/mL and 5.76 ng/mL for amlodipine, and 0.37 ng/mL and 1.23 ng/mL for nifedipine, respectively. The extraction efficiency, evaluated at three concentration levels, resulted in recoveries ranging from 73 % to 98 %. Repeatability analysis showed satisfactory intra-day and inter-day relative standard deviation values: 3.65 % to 8.38 % for amlodipine and 1.9 % to 10.11 % for nifedipine in the intra-day analysis, and 2.46 % to 9.07 % for amlodipine and 2.92 % to 10.7 % for nifedipine in the inter-day analysis. Furthermore, the EP-DLLME method demonstrated environmental sustainability, achieving a total AGREEnness score of 0.68, emphasizing its environmentally friendly nature

Optimization of effervescent tablet-assisted dispersive liquid-liquid microextraction with central composite design for preconcentration of stimulant drug

The extraction efficiency of stimulant drug, namely caffeine, was investigated using a 23 central composite design. The values of optimum extraction condition were set at 468 µL of 1-dodecanol, 1 piece of effervescent tablet, and 22 °C of extraction temperature. An enrichment factor was calculated as 72 for 80 mL water sample. The run time was conducted in less than 6 min using a non-polar C18 column and an isocratic mobile phase (methanol: water of 40:60 (v/v)) at a controlled flow rate of 1 mL min-1. A good linear response was achieved in the range of 0.01-0.50 µg mL-1 (R2 > 0.998). Detection and quantification limits were calculated at 0.009 and 0.015 µg mL-1, respectively. The average recoveries at two spiking concentration levels were within the range of 75-105% with RSD < 2% (n = 3). Real samples namely beverages which contained caffeine and river water were tested using the proposed method, and the results ranged 0.021-0.56 µg mL-1. The eco-scale score and green analytical procedure index confirmed the greenness profile of the proposed method through a calculated score of 88 and has 6 green criteria, respectively

Adsorption of trypsin onto chitosan/Psf affinity membranes: Effects of physio-chemical environment

This study aimed to investigate the significance of the physico-chemical environment during trypsin adsorption onto a highly bio-specific affinity membrane. The affinity matrix polysulfone (PSf) membranes were prepared via a simple dry/wet phase inversion technique. Surface modification of PSf membranes was employed using chitosan in order to improve membrane hydrophilicity. Glutaraldehyde and ovomucoid were used as the membrane activator and affinity ligand, respectively. Inspection of membrane morphology was done using scanning electron microscopy. The functional groups on the membrane surface were determined using Fourier-transform infrared spectroscopy equipped with attenuated total reflection (ATR-FTIR). In order to determine the optimum conditions for the maximum adsorption capacity of trypsin, adsorption studies were performed at different pH levels (5, 7, 8, 10, 12), ionic strengths (0.01, 0.05, 0.1, 0.3 and 0.5 M) and initial trypsin concentrations (0.1, 0.3, 0.5, 0.7 and 0.9 mg/ml). The optimum adsorption was obtained with a 0.9 mg/ml initial trypsin solution at pH 7 and an ionic strength of 0.1

Determination of trace metals in airborne particulate matter of Kuala Terengganu, Malaysia

Results from the present study in Kuala Terengganu, Malaysia indicated a significant spatial variation but generally the total suspended particulate concentrations (mean = 17.2–148 lg/m3) recorded were below the recommended Malaysia guideline for total suspended particulate (mean of 24-h measurement = 260 lg/m3). Some of the elemental composition of particulate aerosol is clearly affected by non crustal sources, e.g. vehicular emission sources. Based on correlation and enrichment analyses, the elements could be grouped into two i.e. Pb, Cd and Zn group with sources from vehicular emission (r[0.6; enrichment factor[10) and Al, Fe, Mn and Cr group that appears to be of crustal origin (r[0.6; enrichment factor\10). It can also be concluded that the mean levels of Pb (1 ng/m3), Cd (0.02 ng/m3) and Zn (2 ng/m3) in the study area are generallylower than other urban areas in Malaysia (Pb\181 ng/m3; Cd\6 ng/m3; Zn\192 ng/m3)