Fast optimisation of a Diels-Alder reaction in a flow microreactor by in-line HPLC analysis

A continuous-flow micro reactor is used for Diels-Alder reactions. Its direct in-line connection to an HPLC allows the analysis and optimization of the reaction on a much shorter time scale than performing the corresponding reactions under batch reaction conditions. A large number of experiments are performed in a short time with minimal reagent consumption. Together with very small volumes of solvents, such an approach provides a green, economical and safe environment for reaction screening

Intelligent Microflow: Development of Self-Optimizing Reaction Systems

A dream come true: Microreactor technology combined with online analysis can be used to optimize reaction conditions. Computer algorithms “decide” which parameters to adjust, and the optimization process itself is optimized

Changes in Organic, Inorganic contents, Carbon Nitrogen ratio in decomposing Avicennia marina and Rhizophora mucronata leaves on tidal mudf lats in Hajambro creek, Indus delta, Pakistan

Leaf decomposition of Avicennia marina (Forskal) Vierh in Denkschr and Rhizophora mucronata (Poiret) was studied in situ using litterbag s in Hajambro creek, Indus delta. A single exponential model was presented, which best described the rate of decomposition for both the species. The rate of decomposition was species specific, A. marina leaves decomposed slower than the R. mucronata (p<0.001). The time in days required for 50% loss of the initial dry mass (t1/2) was 49.55 days for the A. marina and 44.43 days in case of R. mucronata. The organic content in the leaves was high initially but decresed gradually during decomposition, which is negatively correlated with inorganic contents. This study will help in the management and conservation of mangrove ecosystem of Hajambro creek, Indus delta, Pakistan

Studies of Decomposition rate and release of nutrients Ammonium, Nitrates, Nitrites, and Phosphates ions during the decomposition of Oryza coarctata in the laboratory experiment

The vegetation, other than the mangroves in Indus delta, for example Oryza coarctata is also the source of nutrients for the adjacent coastal environment. The O. coarctata is the major vegetation on the tidal mudflatds of Keti-Bunder (Hajambro creek), Indus delta, other than the Avicennia marina and Rhizophora mucronata planted mangrove forest. This is the first report of decomposition rates of O. coarctata in the laboratory. The decomposition of O. coarctata. was conducted to evaluate the nutrients (ammonium, nitrate, nitrites, phosphates) during the decomposition. The decomposition rate was more rapid during this early phase and O. coarctata. decomposed up to 40 % during the first 7 days. Afterwards, the Oryza sp. decomposed slowly and gradually and remained up to 40% of the dry mass. Therefore, about 60% of the organic matter present in the O. coarctata can decompose completely in the aerobic conditions of the aquatic environment. The ammonium ions concentration was found 2.75 μM/L at 7th day and highest value was 6.38 μM/L at 124th day of experiment. So the amount of ammonium ions increased during the phase of decomposition. The nitrate ions concentration was 1.95 μM/L at 7th day and increased to 2.71 μM/L at 15th day of decomposition, and afterwards the concentration of nitrate decreased gradually and lowest value 0.129 μM/L was recorded in the last day of the experiment. The nitrite ions concentration was found 1.80 μM/L and gradually increased to 3.33 μM/L at 60th day and the lowest value was 3.05 μM/L. The initial concentration of the phosphate ions was 0.84 and decresed gradually during the phase of decomposition to its lowest value at 0.7 μM/L. The concentration of the nitrogen in the O. coarctata was initially between 1-1.5 mg DW, which increased to about 2 mg DW at the 7th day of the decomposition. The % DW nitrogen contents than decreased suddenly at 15th day reaching up to about 1 mg DW of the decomposed material. This decrease of the total DW Nitrogen is very important, as it is the source of the nutrients to the adjacent ecosystem. The results are also strongly correlated with the nutrients values

Studies of Decomposition rate and release of nutrients Ammonium, Nitrates, Nitrites, and Phosphates ions during the decomposition of Oryza coarctata in the laboratory experiment

The vegetation, other than the mangroves in Indus delta, for example Oryza coarctata is also the source of nutrients for the adjacent coastal environment. The O. coarctata is the major vegetation on the tidal mudflatds of Keti-Bunder (Hajambro creek), Indus delta, other than the Avicennia marina and Rhizophora mucronata planted mangrove forest. This is the first report of decomposition rates of O. coarctata in the laboratory. The decomposition of O. coarctata. was conducted to evaluate the nutrients (ammonium, nitrate, nitrites, phosphates) during the decomposition. The decomposition rate was more rapid during this early phase and O. coarctata. decomposed up to 40 % during the first 7 days. Afterwards, the Oryza sp. decomposed slowly and gradually and remained up to 40% of the dry mass. Therefore, about 60% of the organic matter present in the O. coarctata can decompose completely in the aerobic conditions of the aquatic environment. The ammonium ions concentration was found 2.75 μM/L at 7th day and highest value was 6.38 μM/L at 124th day of experiment. So the amount of ammonium ions increased during the phase of decomposition. The nitrate ions concentration was 1.95 μM/L at 7th day and increased to 2.71 μM/L at 15th day of decomposition, and afterwards the concentration of nitrate decreased gradually and lowest value 0.129 μM/L was recorded in the last day of the experiment. The nitrite ions concentration was found 1.80 μM/L and gradually increased to 3.33 μM/L at 60th day and the lowest value was 3.05 μM/L. The initial concentration of the phosphate ions was 0.84 and decresed gradually during the phase of decomposition to its lowest value at 0.7 μM/L. The concentration of the nitrogen in the O. coarctata was initially between 1-1.5 mg DW, which increased to about 2 mg DW at the 7th day of the decomposition. The % DW nitrogen contents than decreased suddenly at 15th day reaching up to about 1 mg DW of the decomposed material. This decrease of the total DW Nitrogen is very important, as it is the source of the nutrients to the adjacent ecosystem. The results are also strongly correlated with the nutrients values

Microwave Assisted Reduction for Screening Banned Aromatic Amines in Azo Dyes

The study proposes a simple, novel and green alternative for the efficient reduction of azo dyes by the standard method, EN 14362-1:2012 (Annex. F) for detection of harmful aromatic amines in colorants, by incorporating microwave heating in place of convective heating. Basic dye response to reduction methods was explored by UV-visible spectroscopy and the results were confirmed through GC-MS and HPLC-DAD. Four azo dyes namely Acid red 1 (AR-1), Direct blue 15 (DB-15), Direct red 28 (DR-28) and Direct red 7 (DR-7) were reduced with sodium dithionite at 70 °C for 30 min in a buffered solution at pH 6.0, serving as a reference method. The decline in dye absorbance after their reduction was explored by UV-visible spectroscopy with carefully chosen bands of maximum absorbance from 300 to 700 nm. The alternative method exposed dye solutions to short microwave heating (10 s) and immediate cooling, in cycles till the desired duration of microwave heating was achieved. Results obtained from reference method were used for comparison with MAR (experimental method 1). Most prominent results of MAR were observed in the case of DR-28 dye. Hence DR-28 was further subjected to the conditions of experimental method 2, which was simply EN 14362-1:2012 (F) method modified with MAR. For standard method and experimental method 2, amines were analysed by GC-MS and HPLC-DAD. MAR methods were compared with reference and standard reduction methods for efficiencies. The total saving with MAR in terms of time and energy was ~70% and ~92% respectively

Microwave Assisted Reduction for Screening Banned Aromatic Amines in Azo Dyes

The study proposes a simple, novel and green alternative for the efficient reduction of azo dyes by the standard method, EN 14362-1:2012 (Annex. F) for detection of harmful aromatic amines in colorants, by incorporating microwave heating in place of convective heating. Basic dye response to reduction methods was explored by UV-visible spectroscopy and the results were confirmed through GC-MS and HPLC-DAD. Four azo dyes namely Acid red 1 (AR-1), Direct blue 15 (DB-15), Direct red 28 (DR-28) and Direct red 7 (DR-7) were reduced with sodium dithionite at 70 °C for 30 min in a buffered solution at pH 6.0, serving as a reference method. The decline in dye absorbance after their reduction was explored by UV-visible spectroscopy with carefully chosen bands of maximum absorbance from 300 to 700 nm. The alternative method exposed dye solutions to short microwave heating (10 s) and immediate cooling, in cycles till the desired duration of microwave heating was achieved. Results obtained from reference method were used for comparison with MAR (experimental method 1). Most prominent results of MAR were observed in the case of DR-28 dye. Hence DR-28 was further subjected to the conditions of experimental method 2, which was simply EN 14362-1:2012 (F) method modified with MAR. For standard method and experimental method 2, amines were analysed by GC-MS and HPLC-DAD. MAR methods were compared with reference and standard reduction methods for efficiencies. The total saving with MAR in terms of time and energy was ~70% and ~92% respectively