Richard C.S. Wong

Environmental influences on bacterial diversity of soils on Signy Island, maritime Antarctic

Soil bacterial diversity at environmentally distinct locations on Signy Island, South Orkney Islands was examined using the denaturing gradient gel profiling approach. A range of chemical variables in soils at each site was determined in order to describe variation between locations. No apparent differences in Shannon Diversity Index (H′) were observed. However, as revealed in an analysis of similarity (ANOSIM), the dominant bacterial communities of all eight studied locations were significantly different. Within this, higher levels of similarity were observed between penguin rookeries, seal wallows and vegetated soils, all of which share varying levels of impact from vertebrate activity, in contrast with more barren soil. In addition, the lowest H′ value was detected from the latter soil which also has the most extreme environmental conditions, and its bacterial community has the greatest genetic distance from the other locations. DGGE analyses indicated that the majority of the excised and sequenced bands were attributable to the Bacteroidetes. Across a range of ten environmental variables, multivariate correlation analysis suggested that a combination of pH, conductivity, copper and lead content potentially contributed explanatory value to the measured soil bacterial diversity.

Gas chromatographic method validation for the analysis of major components in illicit heroin seized in Malaysia.

Apart from routine analysis of total morphine content required by the criminal justice system, quantification of other major components in illicit heroin has not been considered by the Malaysian enforcement laboratory. In order to quantify various other cutting agents in addition to alkaloids, a gas chromatographic (GC) method was developed to facilitate simultaneous quantification of eight target analytes commonly found in illicit heroin seized in Malaysia within a 12 min run time. The validation results demonstrated high selectivity with the use of an HP Ultra 2 capillary column. Different solvents were studied and methanol:chloroform (1:9) proved best for sample dissolution. The method was repeatable and reproducible. The study ranges covering 50-150% of the preferred concentrations of the eight analytes obtained r(2)>0.9997. Limits of detection up to 6μg/mL were also obtained and the method achieved 99-102% recovery. The capability of the method in heroin profiling was verified using samples from ten case samples.

Investigation of trace inorganic elements in street doses of heroin

Sixteen trace elements found in 309 street heroin samples, piped water and contaminated water were determined using inductively coupled plasma-mass spectrometry. All the street heroin samples were found to contain high levels of sodium, a reflection of the use of sodium bicarbonate during heroin synthesis. Additionally, this element was also found to be one of the potential contaminants acquired from the piped water. Calcium could be derived from lime while iron, aluminum and zinc could have come from the metallic container used in the processing/cutting stage. The levels of these elements remained low in the heroin and it could be due to the dilution effects from the addition of adulterants. Statistical validation was performed with six links of related heroin samples using principal component analysis to find the best pretreatment for sample classification. It was obtained that normalization followed by fourth root showed promising results with 8% errors in the sample clustering. The technique was then applied to the case samples. Finally, the result suggested that the case samples could have originated from at least two major groups respectively showing unique elemental profiles at the street level.

QuEChERS-HPLC METHOD FOR AFLATOXIN DETECTION OF DOMESTIC AND IMPORTED FOOD IN JORDAN

A method for the analysis of aflatoxins in food samples was developed. The preliminary work focused on optimizing sample pretreatment conditions such as the extraction solvent; the type and amount of drying agents; the extraction time; and the solvent-sample ratio. A 60:40 methanol/acetonitrile (%, v/v) extraction mixture provided recoveries in the range of 71.8–107.7% at spike levels of 1.5–50.0 µg/kg with relative standard deviations (RSDs) lower than 15%. The separation of the four aflatoxin compounds with high selectivity and sensitivity, and within reasonable retention times, was performed by a C18 250 mm × 4.6 mm × 5 µm column (Nucleodur 250-5) at 45°C. The developed QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure, high performance liquid chromatography (HPLC) method was then compared with the fluorometric determination method. It was found that the fluorometric determination method had a poor precision and positive bias as compared to QuEChERS-HPLC method. A total of 669 domestic and imported food samples in Jordan were analyzed for their aflatoxins content. Peanut and peanut butter samples showed the highest incidence of contamination (10 contaminations) followed by pistachio nut samples (6 contaminations) and sesame seed samples (2 contaminations).

Coordination of Cp2Cr2(CO)4(μ-η2P2) to metal carbonyl fragments and crystal structure of Cp2Cr2(CO)4− (μ-η2-P2)[Cr(CO)5]2

Cp2Cr2(CO4(μ-η2-P2) (I) reacts with 2 mole equivalents of M(CO)5THF to give Cp2Cr2(CO)4(μ-η2-P2)[M(CO)5]2 (M = Cr, II; Mo, III; W, IV) in 65–70% yields. The reaction with 1 mole equivalent of Cr(CO)5THF gave the mono-metallated complex Cp2Cr2(CO)4(μ-η2-P2[Cr(CO)5] (V) in 60% yield along with II in 18% yield. In the presence of stoichiometric amount of PPh3 as a Cr(CO)5 scavenger, II was converted into V and I. X-ray analysis showed that II has C2 molecular symmetry; the CrCr′ and PP′ bond distances in the tetrahedral Cr2P2 core are 3.003(1) and 2.063(1) A, respectively.

Linkage of a pentacarbonylchromium fragment to a (μ-η2-P2)Cr2 core. Crystal structure of Cp2Cr2(CO)4)(μ-η2-P2)[Cr(CO5)]

Abstract The complex Cp2Cr2(CO)4(μ-η2-P2)[Cr(CO)5] (2) formed in the reaction of Cp2Cr2(CO)4(μ-η2-P2) (1) with one molar proportion of Cr(CO)5(THF), has been structurally characterized. Crystal data: triclinic, space group P 1 , a 7.859(4), b 9.948(5), c 16.209(8) A, α 104.29(3), β 97.30(3), γ 108.90(3)°, and Z = 2. The molecular geometry of 2 is compared with those of 1 and Cp2Cr2(CO)4(μ-η2-P2)[Cr(CO)5]2 (3).

Statistical validation for the profiling of heroin by associating simulated postcut samples with the corresponding precut sample.

Statistical validation is crucial for the clustering of unknown samples. This study aims to demonstrate how statistical techniques can be optimized using simulated heroin samples containing a range of analyte concentrations that are similar to those of the case samples. Eight simulated heroin distribution links consisting of 64 postcut samples were prepared by mixing one of two mixtures of paracetamol–caffeine–dextromethorphan at different proportions with eight precut samples. Analyte contents and compositional variation of the prepared samples were investigated. A number of data pretreatments were evaluated by associating the postcut samples with the corresponding precut samples using principal component analysis and discriminant analysis. Subsequently, combinations of seven linkage methods and five distance measures were explored using hierarchical cluster analysis. In this study, Ward–Manhattan showed better distinctions between unrelated links and was able to cluster all related samples in very close distance under the known links on a dendogram. A similar discriminative outcome was also achieved by 90 unknown case samples when clustered via Ward–Manhattan.

Investigation of illicit heroin seized in Malaysia: physical characteristics and chemical profiling

The high number of illicit heroin cases in Malaysia has led to the local forensic laboratory profiling of the physical and chemical characteristics of 311 street samples submitted as heroin cases in 2010. Visual examination and physical characteristics of the heroin substance and plastic packages are described. The preferred ranges of the weight of substances per package and the dimensions of the plastic package/receptacle are defined. Analysis of eight major components (three adulterants and five opium alkaloids) is also detailed. It was found that most samples contained less than 10% heroin base and more than 80% caffeine. Physical and chemical data together provide a quick overview of the samples seized within the country. Principal component analysis of the five major opium alkaloids present in the seized samples suggested that there were at least two sources responsible for the samples analyzed.

A new type of polycyclophosphidochromium cluster, [(Cp)Cr(CO)2]5P10(Cp =η5-C5H5). First observation of polycylic P-to-M coordination

The co-thermolysis of [(Cp)Cr(CO)3]2(Cp =η5-C5H5) with P4 forms [(Cp)Cr(CO)2]5P10, a new paramagnetic structure with a P10 core, which represents the first example of polycyclic phosphorus-to-metal coordination.

Forensic Applications of IR Spectral Data at Macro and Micro Levels: A Study on Plastic Packages

ABSTRACT Plastic packaging is one of the most commonly used methods among illicit heroin packers. Distribution starting from the manufacturer to the end users may involve replacement of larger plastic bags with smaller packets as the mass of heroin is divided into smaller portions for street sales. Conventionally, polymeric compositions of these materials are often used qualitatively to distinguish between the types of plastic packets the drug distributors tend to use. In addition, spectral differences when statistically manipulated can also help further differentiate the plastic packets of a particular type. In this study, the IR technique has identified five polymeric types at the macro level from 311 heroin cases involving the use of plastic packages. The most frequently encountered Type 1-Polypropylene-based plastic packets were further distinguished at the micro level by principal component analysis after IR data pretreatment. Possible forensic interpretations about the packers involved in heroin cases were also outlined based on the findings obtained at the two levels. Using IR technique alone is the preliminary step in forensic profiling. Further analysis of other aspects associated with these packages is required for more precise intelligence work.