Simple and sensitive determination of 2,4-xylenol in surface water samples from river and sea by gas chromatography-mass spectrometry

[Development of methods for determining and studying the persistence of 2,4-dimethylhydroxybenzene and 2,6-dimethylhydroxybenzene in biological material]

OBJECTIVE

To study the features of the determination and preservation of 2.4-dimethylhydroxybenzene and 2.6-dimethylhydroxybenzene in biological material. Extraction, semi-preparative chromatography, TLC, GC-MS and UV spectrophotometry are considered as methods of analysis. The 2.4- and 2.6-dimethylhydroxybenzenes were isolated from the biomaterial by double infusion (30 minutes each) with a mixture of ethyl acetate-acetone (7: 3) at a weight ratio of the insulating liquid and biomaterial of 2:1. Purification was carried out by extraction and chromatography in a semi-preparative (190×10 mm) column of silica gel L 40/100 µm using the eluent hexane-dioxane-propanol-2 (80: 5: 1). Analytes were determined by TLC (Sorbfil plates, mobile phase hexane-dioxane-propanol-2 (120: 5: 1)), GC-MS (DB-5MS EVIDEX column (25 m × 0.2 mm) with a stationary phase (5%-phenyl) - methylpolysiloxane), UV spectrophotometry (solvent - 95% ethanol). The developed methods for the determination of 2.4- and 2.6-dimethyl derivatives of hydroxybenzene in biomaterial (liver tissue) are validated according to the criteria of linearity, selectivity, correctness and precision. The study of the dynamics of decomposition of 2.4- and 2.6-dimethyl hydroxybenzene derivatives in model mixtures with liver tissue, carried out using the developed techniques showed that with an increase in temperature the duration of preservation of analytes in biological material decreases. Moreover, the 2.4-isomer is more stable during storage than the 2.6-isomer. At temperatures of -25 °C, 0-2 °C, 8-10 °C, 20-22 °C, 36 °C the duration of retention of 2.4-dimethylhydroxybenzene is 402, 379, 358 and 224 days, respectively, the duration of retention of 2.6-dimethylhydroxybenzene is 356, 312, 224 and 136 days, respectively.

Exploring the prospective of weeds (Cannabis sativa L., Parthenium hysterophorus L.) for biofuel production through nanocatalytic (Co, Ni) gasification

BACKGROUND

While keeping in view various aspects of energy demand, quest for the renewable energy sources is utmost. Biomass has shown great potential as green energy source with supply of approximately 14% of world total energy demand, and great source of carbon capture. It is abundant in various forms including agricultural, forestry residues, and unwanted plants (weeds). The rapid growth of weeds not only affects the yield of the crop, but also has strong consequences on the environment. These weeds can grow with minimum nutrient input requirements, have strong ability to grow at various soil and climate environments with high value of cellulose, thus can be valuable source of energy production.

RESULTS

Parthenium hysterophorus L. and Cannabis sativa L. have been employed for the production of biofuels (biogas, biodiesel and biochar) through nano-catalytic gasification by employing Co and Ni as nanocatalysts. Nanocatalysts were synthesized through well-established sol-gel method. SEM study confirms the spherical morphology of the nanocatalysts with size distribution of 20-50 nm. XRD measurements reveal that fabricated nanocatalysts have pure standard crystal structure without impurity. During gasification of Cannabis sativa L., we have extracted the 53.33% of oil, 34.66% of biochar and 12% gas whereas in the case of Parthenium hysterophorus L. 44% oil, 38.36% biochar and 17.66% of gas was measured. Electrical conductivity in biochar of Cannabis sativa L. and Parthenium hysterophorus L. was observed 0.4 dSm-1 and 0.39 dSm-1, respectively.

CONCLUSION

Present study presents the conversion of unwanted plants Parthenium hysterophorus L. and Cannabis sativa L. weeds to biofuels. Nanocatalysts help to enhance the conversion of biomass to biofuel due to large surface reactivity. Our findings suggest potential utilization of unwanted plants for biofuel production, which can help to share the burden of energy demand. Biochar produced during gasification can replace chemical fertilizers for soil remediation and to enhance the crop productivity.

A pair of concentric capillaries as an interface for gas chromatography and supersonic jet/multiphoton ionization/mass spectrometry

A pair of concentric capillaries was developed to mix helium, which was used as the carrier gas for gas chromatography, with argon for efficient molecular cooling by supersonic jet expansion. A simple instrument was constructed for the evaluation of nozzle diameter using the Hagen-Poiseuille equation. The effects of nozzle diameter, type of expansion gas, flow rate, and the distance from the nozzle to the observation region were investigated. Mixing argon gas with the carrier gas helium resulted in efficient molecular cooling from 30 to 10 K and the complete disappearance of the background signal from the multiphoton ionization spectrum. Consequently, the spectral selectivity was significantly improved and the nozzle was successfully applied to isomer-selective analysis of dichlorotoluenes. Since the dead volume in the nozzle was negligible, it was suitable as an interface for gas chromatography and supersonic jet/multiphoton ionization/mass spectrometry.