Glimpses of current research
A novel analytical approach based on molecularly imprinted solid phase extraction (MISPE) coupled with dispersive liquid-liquid microextraction (DLLME), and injector port silylation (IPS) was developed for the selective preconcentration, derivatization and analysis of 3-phenoxybenzoic acid (3-PBA) using gas chromatography-tandem mass spectrometry (GC-MS/MS) in complex biological samples such as rat blood and liver. The developed method offers a good linearity over the calibration range of 0.02-2.5 ng mg-1 and 7.5-2000 ng mL-1 for liver and blood respectively with recoveries ranging from 83-91%.
Metabolomics provides a unique opportunity to find out biomarkers of nanoparticles exposure, which leads to the identification of cellular pathways and their biological mechanisms. Gas chromatography mass spectrometry (GC-MS) based metabolomics approach was used in a study to understand the toxicity of sub-lethal concentrations (7.7 µg/ml and 38.5 µg/ml) of TiO2 NP (< 25 nm) in well known soil nematode Caenorhabditis elegans (C elegans). Multivariate pattern recognition analyses reflected the metabolomics perturbations (amino acids, organic acids, sugars) in C elegans after their exposure to TiO2 NP. In another study, metabolomics based approach was utilized to identify the toxic mechanism of action of cypermethrin on earthworm (Metaphire posthuma). The statistical treatment for the data based on multivariate pattern recognition revealed that 22 metabolites including fatty acids, sugars, and amino acids were shown significant responses in the exposed population in comparison to control. The study demonstrated that metabolomics can be employed as a tool to understand the potential toxicity of toxicants in terms of organism-environment interactions and for assessing the organism function at molecular level.
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants and well known carcinogens. Hydroxy derivatives of PAH are considered as biomarkers of PAH exposure. For the first time, a new analytical method based on coupling of dispersive liquid-liquid microextraction (DLLME) with auto-injector port silylation (auto-IPS) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis is reported for the analysis of seven urinary polycyclic aromatic hydrocarbon (PAH) metabolites.
Quantum dots (QDs), one of the fastest developing and most exciting fluorescent materials have attracted increasing interest in bioimaging and biomedical applications. The long term stability and emission in visible region has proved the applicability of QDs as significant fluorophore in cell labelling. The aqueous and room temperature synthesized QD with L-cysteine as a capping agent was found to be non-toxic even at the concentration of 1,500 µg/mL and this also found to be water dispersible, non-toxic and have wide applications in bio imaging.
An ultrasensitive method for the determination of 18 organophosphorus pesticides from small quantity (100µl ) of biological fluids was developed using automated and nearly solvent-less micro extraction. All the major parameters affecting the extraction efficacy were optimised. The method was very sensitive with detection values (LODs) within the range of 0.0009 - 0.122 µg L-1 for all pesticides from spiked blood samples with linearity correlation coefficients ranging from 0.987 to 0.999. Recovery of the analytes were 85%. The study exhibits that focus on automation of the method is necessary for getting reliable results.
A novel, sensitive, rapid, precise and efficient miniaturized low density solvent vortex agitated liquid-liquid micro extraction (LD-VALLME) with Tandem mass spectrometric method was developed for the estimation of BPA in cash register receipts (Thermal paper) without derivatisation for the first time. The detection and quantification limit of BPA in thermal papers were found to be 1.12 and 3.27 µg/kg respectively. Correlation coefficient (r2) was 0.999 at the levels of 0.005 - 1 µg/ml. Matrix effect was also evaluated for different samples like napkin, tissue, printing, news, photographic and thermal papers.
A novel, rapid, easy and efficient liquid-liquid micro extraction method (LLME) was developed for the extraction and quantification of 4-Hydroxyisoleucine (4-HIL) using LCMS/MS with electro spray ionisation. The main goal was to determine 4-HIL ions 148/129 and 148/102 in fenugreek seed samples. Optimized conditions were applied to determine 4-HIL ions in thirty samples from local market of Lucknow. The limit of detection (LOD) values of the proposed method under optimized multiple reaction monitoring (MRM) mode for 4-HIL I and II ions were 1.05 ng/g and 3.49 ng/g respectively. The limit of quantification (LOQ) values for 4-HIL I and II ions were 3.07 ng/g and 10.24 ng/g respectively and linearity ranges from 10-640 ng/g were evaluated.
Safety evaluation studies of finished products, raw materials, new chemical entities etc are being carried out by this group. This activity has further been strengthened by the facility being accredited as a GLP Certified Facility by the National GLP Compliance Monitoring Authority (NGCMA), Govt. Of India w.e.f. June, 2014.