Solvents - Science topic

Dear all, you forgot to mention the solvent in which the polymer is soluble! This is crucial in choosing the best non-solvent. Other important remark that is not considered by many researchers in doing precipitation. There are two possibilities, either to add the solution to the non-solvent or to add the non-solvent to the solution. The first one is the correct way that is not unfortunately followed by many researchers. When you add the non-solvent to the solution, long chains are more sensitive to its presence, they contract first, followed by the shortest chains. This is a chromatographing or a fractionation phenomenon. At the end, the resulted mass is a gradual decrease of MW from the core to the outer surface. I noticed this with polyacrylamide. Samples from the surface have different features compared to those taken from the core, mainly MW.

For the second procedure, pouring the solution into the non-solvent resulted in homogeneous mass since long and short chain are following simultaneously into the non-solvent, so they precipitate together, resulting in a uniform mass. My Regards

Farha Memon

The production of copper nanoparticles from ions occurs in a solvent (water) as a result of redox reactions. These reactions do not readily occur in powder (dry) form. Their disadvantages: they require stirring and then heating. In this case, sintering of nanoparticles will still occur. To preserve nanoparticles, they must be stabilized in suspension in a solvent. Conclusion: the answer to your question is negative.

Dear all, if you have clear and homogeneous solution, then you may expect interactions. Solubility means there is such mutual interactions. Both water and acetic acid are polars, that's why they are soluble, the same would be with residual monomers, which are automatically polar since they are soluble in water. My Regards

Ams Jekhan Common solvents for dissolving reduced graphene oxide (rGO) include N,N-Dimethylformamide (DMF), ammonia solution, hydroquinone, hydroxyrazine hydrate, and ascorbic acid.

You are most welcome

thank you so much

hi, may i know, i want to prepare DES. but I am unsure is DES only between two chemicals heated togewther? or need to dilute with distilled water? im planning to do 1:1 molar ratio of chcl:lactic acid

Dear Ramazan Kazhdanbekov, the question about solvents and solubility of PANI wsa treated so many times at RG platform, please check these threads by simple search. PANI has no solvent, the best you can get roughly stable dispersion. If solubility of PANI is crucial for processing gas sensors, then try low molecular mass one, may be you will be lucky to form a more or less good processable solution. My Regards

I plan to tackle this question by: a) Optimizing the geometry without PCM initially, then reverting to your original settings, and b) Slightly perturbing the geometry and returning to the initial setup if any configuration issues arise.

Respected Mariana Colaço

To aliquot polymyxin B sulfate salt (P4932-1 MU) from Sigma-Aldrich, begin by preparing a stock solution of the desired concentration, following the instructions provided by Sigma-Aldrich or referencing the product datasheet. Once the stock solution is prepared, ensure proper sterilization techniques are employed to maintain purity and prevent contamination. Using an aseptic technique, dispense the desired volume of the stock solution into sterile aliquot tubes, taking care to avoid introducing air bubbles. Seal the aliquot tubes securely to prevent evaporation or contamination during storage. Label each aliquot tube with the date of preparation, concentration, and other relevant information. Store the aliquots at the recommended temperature and conditions specified by Sigma-Aldrich to maintain stability and functionality.

Respected Utsw Employee

To ensure that casein remains in solution during storage, it's essential to maintain proper conditions and prevent factors that could lead to precipitation. When using TBST as the solvent, thoroughly dissolving casein and gentle mixing can help prevent its settling. Storing the solution at 4 degrees Celsius also slows molecular movement, reducing the likelihood of casein coming out of the solution. However, over time, precipitation may occur despite these precautions. To minimize this risk, periodic gentle agitation or stirring of the solution during storage can help redistribute any settling particles and maintain homogeneity. Additionally, adding stabilizing agents such as protease inhibitors or glycerol to the solution may help prevent precipitation and maintain the stability of the casein solution over extended storage periods.

Water, alcohol

To recrystallize the hydrazone from 2,4-dinitrophenyl hydrazine and salicylaldehyde, consider these solvents since ethanol is ineffective:

Please note that choose the solvent based on solubility tests for effective recrystallization

1. Water

2. Dilute Acetic Acid

3. Methanol

4. Acetonitrile

5. Dichloromethane/Hexane mix

Steps:

1. Test Solubility: Select a solvent that dissolves the hydrazone when hot but allows crystallization when cooled.

2. Dissolve and Cool: Heat to dissolve, then cool to precipitate.

3. Filter and Dry: Collect and dry the crystals.

There is no fixed relation between solvent and edge specific of GQDs , the edge frame synthesis regards to methodology and precursor you intimate with !

Mix 1 volume of 72% sulfuric acid with 23 volumes of water (resulting in a 24-fold dilution). This is a simplified version of the well-known formula V1N1=V2N2

Sylwia Katarzyna Król

One can sterilize the solution by filtering through a 0.1-μm filter unit. Filter sterilization removes all suspended particles with a size of more than 0.1 μm which includes most bacteria and their spores but not mycoplasma. Moreover, it does not inactivate enzymatic activities (e.g., DNases). Autoclaving inactivates most enzymes except some (e.g., RNases) and kills most microorganisms including mycoplasma.

Hey there Hariharan S Melarcode!

Absolutely, finding green solvents for PLA dissolution is crucial. While PLA is known to dissolve well in solvents like DCM and Ethanol mixtures, as well as DMF, Acetone, THF, and Chloroform, let's explore some greener options.

One good option is **lactic acid** itself, which is the monomer of PLA. It can act as a solvent for PLA, making it both efficient and environmentally friendly.

Another option is **ethyl lactate**, a derivative of lactic acid. It's biodegradable and can efficiently dissolve PLA.

**Ionic liquids** are also worth considering. Although they're not always considered "green" due to concerns about toxicity, some ionic liquids have been developed that are both efficient and more environmentally friendly.

Lastly, **supercritical CO2** is an interesting choice. While it's not a traditional solvent, it can be used in combination with a co-solvent to dissolve PLA effectively. Plus, CO2 is non-toxic and readily available.

So, in summary, while the traditional solvents you mentioned work well, these greener options provide efficient and eco-friendly alternatives for dissolving PLA.

Ankit Mishra THF and chloroform are also toxic for medical or food technological applications. I am looking specifically for green solvents to dissolve PLA efficiently and effectively. If you do know any, please share it here. Thanks

Вакуумно-паровая экстракция из сырья завода и оборудование «Альфа-Эфир-Вакуум» для получения вакуумных экстрактов.

Dear all, there are many possibilities to get the required MW. If you have the kinetics curve of the polymerization reaction, i. e., MW vs time or MW vs %conversion, then all to do is to quench the reaction at the time or % conversion corresponding to the targeted MW. The second solution is to do dialysis fractionation with a memebrane with the specific MW cut-off. The third possibility is to do mechanical degradation by shearing either by high speed agitator or passing through low porosity sieves.

If you want to avoid these extra work, choose a solvent with high transfer constant, and reduce the polymerization temperature. Starve feeding of the monomer may also help to reach a moderate MW. My Regards

You can visualize final .gro file that you generated as output in VMD and then by clicking load data into molecule you have to select .xtc file and thus you can visualize trajectory for simulation run time.

Hey there Shivaya shambhu Shiv! When it comes to investigating unknown peaks, especially in residual solvents and related substances, the go-to guideline is typically outlined in pharmacopeias like USP, EP, or JP. These guidelines offer structured approaches for the identification and evaluation of unknown peaks in chromatographic analysis.

As for the limit of unknown peaks in parts per million (PPM), it varies depending on the specific regulatory requirements or industry standards applicable to your analysis. However, a common practice is to set acceptance criteria based on the sensitivity of the analytical method and the potential impact on product safety and quality.

Calculating the concentration of an unknown peak in PPM involves comparing its peak area or height to that of a known standard or internal standard. By relating these measurements to the sample concentration, you Shivaya shambhu Shiv can determine the PPM value.

For a more precise answer tailored to your Shivaya shambhu Shiv specific situation, it's best to consult the relevant regulatory guidelines and standards applicable to your industry or region. If you Shivaya shambhu Shiv need further assistance or clarification, feel free to ask!

To all my folks, Use acetonitrile.

Petroleum ether is a mixture of various alkanes. According to the IUPAC solubility data series, vol. 58, the solubility of dibenzo[a,h]anthracene in heptane would be 0,00034mol/l, but with your values you're trying to prepare 0,036mol/l unless I just severely miscalulated something, so you probably made a saturate solution with a much lower concentration than you hoped for.

The data is rather old, so there might be better options these days. The chemicalbook pake Iaroslav Kuziv hinted at indicated that actual ether might work better, but without quantitative data I don't want to give you hopes that you will reach your desired concentration.

Roderick Abdilla I’d consider drying your silica at 150 - 200 C before the activation with HCl and after activation in a similar manner. Keep in a desiccator before use.

Dear Zhong Zheng, if these are conventional addition polymerization monomers, their relative reactivities are known, i.e., their reactivity ratios will help to estimate the relative presence and most probable sequence distribution of the three monomers along the chains, but it stays only a rough approximation. NMR is the best tool to analyse the the synthesized tripolymer. My Regards

Does your solvent contain any charged components, i.e. ions, salts? Mobile charge carriers are a prerequisite for conducting current.

Thank you for your advice Kaushik Shandilya

Hey there Michelle Darmawan!

Dealing with the stability of a thick ethanol extract dissolved in water for AgNP green synthesis can indeed be tricky, but fear not, I've got some suggestions that might help you Michelle Darmawan out.

First off, kudos on the maceration technique using 70% ethanol solvent. That's a solid approach for obtaining a thick extract. Now, onto the stabilization conundrum:

1. **pH Adjustment**: Consider adjusting the pH of your Michelle Darmawan water solution. Sometimes, precipitates form due to pH imbalances. Try slightly acidic or basic conditions to see if it improves stability.

2. **Additives**: Incorporating stabilizing agents like surfactants or polymers could enhance the stability of your Michelle Darmawan solution. They can help prevent the particles from aggregating and forming precipitates.

3. **Temperature Control**: Temperature plays a crucial role in stability. Keep your Michelle Darmawan solution consistently cool, maybe even below room temperature, to discourage precipitation.

4. **Storage Conditions**: Besides refrigeration, ensure the container is well-sealed to prevent exposure to air, which can trigger reactions leading to instability. Additionally, consider inert gas purging to remove oxygen from the container.

5. **Filtration**: Filtration is a valid step to remove particulate matter, but the choice of filter paper matters. Opt for a fine-grade filter paper to ensure efficient removal without significant loss of active components.

6. **Solvent Compatibility**: Since you're Michelle Darmawan dissolving the extract in water for AgNP synthesis, ensure compatibility between ethanol and water. Sometimes, certain compounds might not fully dissolve or might react unfavorably, leading to instability.

Experimentation is key here. Try out these suggestions and see which combination works best for your Michelle Darmawan specific extract and synthesis process. Remember, a bit of trial and error is often par for the course in research. Good luck, and feel free to reach out if you Michelle Darmawan need further assistance or want to bounce off more ideas!

V H Krishna Prasad If you have a powdered material, it's a general rule that size measurement is via laser diffraction rather than DLS. This is because there are no free, independent, discrete particles < 100 nm in a powder. A powder contains post- and sub-micron aggregates and agglomerates. Further zeta potential is a holistic property of the system - the particle and the fluid it is suspended in. As such, parameters such as pH play an important role in determining zeta potential (ZP). ZP is never directly measured but inferred from a mobility (movement) measurement in an electrical or acoustic field.

You are not dissolving the material in the fluid but dispersing it. Take a look at this webinar (free registration required):

Dispersion and nanotechnology

Further:

Adhesion and cohesion

Hello Noor Rehman

I managed to make a suspensions of ZnO and TiO2 nanoparticles, in ethanol. I tried concentration of 5 mg/mL, it gave me the behaviour I expected, but you must try less concentrated, like 1 mg/mL and 0.5 to check the result. I would say to you test what suits best for your nanoparticle, and find out if there is any solvent that harm your compound. For ZnO I could use water, but for TiO2 water was not suitable, so I used ethanol.

Best regards,

Ricardo Tadeu

There is a whole chapter on effects of solvents on florescence emission spectra in Joseph Lakowicz's textbook "Principles of Fluorescence Spectroscopy" (Chapter 7 in the 1st edition). He divides solvent effects into general and specific types. The following is an excerpt from p. 189.

"By general solvent effects we mean those which result from the refractive index (n) and dielectric constant (epsilon)....Specific solvent effects refer to specific chemical interactions between the fluorophore and the solvent molecule, such as hydrogen bonding and complexation."

The rest of the chapter goes into details.

If you are using a PCL with MW 80000 you can get bead free fibers using CLF:DMF 80:20 an a concentration about 12%wt.

Also around 18%wt. In DMF will led you to bead free fibers.

I hope this can help you

Best regards

You could have Gaussian calculate the absolute dipole moment of your monomer molecules; then you check your optimized geometry how those dipoles then would stand and apply the general formula for dipole-dipole interaction:

(the last formula at the bottom)

Then you should receive an energy which you can subtract from your binding energy; the remainder is the binding part that's not from dipole force.

Amending my previous answer: You may be able to disperse GaN in liquid gallium (6.1 g/cc), or if you want it to float on top (also not to worry about the liquid freezing overnight), in galinstan (6.4 g/cc). Galinstan is a Ga-In-Sn eutectic that is used, among other uses, to replace mercury in medical thermometers. There are also a variety of heavier liquid alloys based on heavy metals such as Bi, In, Sn, and if toxicity is not a consideration, Pb, Cd and Tl. All those however melt considerably above room temperature and are likely to be inferior to Ga and galinstan with respect to wetting GaN.

Dear Amirali Salimi ! Without grinding, the swelling kinetics will not allow the dissolution of rubber on an industrial scale. A shredder, a lathe or a guillotine in cutting mode will do. There are other ideas. But this can be discussed in private, since this information has commercial significance.

As pointed out by Jeremy Pronchik , it is not necessarily true that a given protein molecule is either fully active and in its native conformation or fully inactive and unfolded. A protein molecule's structure might be mildly perturbed by a low concentration of DMSO and retain partial activity. High solvent concentrations, on the other hand, would probably result in major loss of native structure of most proteins.

If a solution of a protein at a reasonably high protein concentration is substantially unfolded, it will almost certainly result in aggregation of protein molecules due to exposure of the hydrophobic interior. In this extreme case, a simple measurement by dynamic light scattering will reveal the presence of aggregated protein. This requires a special instrument, but if the aggregation is severe enough, it can even be detected with a UV-VIS spectrophotometer, which most labs have.

The effect of a solvent or other chaotrope on the stability of a protein can be monitored by measuring the melting temperature of the protein in solution, using either differential scanning calorimetry, or differential scanning fluorescence. Each measurement requires a special instrument.

Many proteins contain tryptophan residues whose fluorescence is sensitive to their environment, specifically the hydrophobicity of their environment. Using a spectrofluorimeter, you can measure the tryptophan emission spectrum to follow major and minor structural changes in the protein. This can also be done using far UV circular dichroism (CD).

Far UV CD, mentioned by Jeremy Pronchik is used to measure changes in the secondary structure elements of the protein. Loss of secondary structure would be a sign of a major loss of native structure. I think the presence of DMSO would interfere with this measurement, however.

better to go for further extraction with acid-base reaction with organic solvents and after add dil acid the acid aqueous layer my contain.

Cross-linking serves to connect an assembly of loose polymer molecules into a macroscopic network. This operation can be carried out either in solution, turning a polymer solution (fluid) into a gel (solid), or in an undiluted monomer mixture by co-polymerization. At a molecular scale, the cross-linking process results in creating permanent ‘junction zones’ (= linkages between two (or more) different molecules) into the polymer assembly. Although linkages can be of physical nature, like double helices or crystalline domains in biopolymers, I limit myself to chemical cross-linking.

There are 2 basic methods for chemical cross-linking:

The first type involves a co-polymerization reaction, generally conducted without dilution, where a small amount of e.g. a trifunctional monomer (= a monomer containing 1 branching point) is added to the bulk of bifunctional monomer. Polymerization without trifunctional monomer gives a linear polymer.

The second type involves a reaction between pre-existing linear polymer molecules and a bifunctional small molecule that links the polymer molecules together. This kind of cross-linking is generally conducted in solution.

The (molar) degree of cross-linking (DCL) is roughly calculated as the (molar) ratio tri-/bifunctional monomer or cross-linker/monomer applied. This gives a very rough approximation only, (1) because reaction efficiency is generally < 100 %, and (2) because small molecular assemblies may be produced with insufficient connection to take part of the network. A better approach is to wash the network exhaustively with a good solvent and analyse the purified network for the amount of cross-linker. This is hampered by the often very low DCL values applied and the lack of suitable analytical methods.

Variation of DCL is applied to tailor the mechanical and swelling properties of the network. At increased DCL the network structure becomes more dense. This results in a higher mechanical modulus (G) and a lower swelling power (q). Relationships between G or q and DCL have been derived, based on the theory of polymer physics. More often than not, DCL is not measured but estimated from G or q values. For details: despite its age I can still recommend the classical book of Nobel laureate Paul Flory: P.J. Flory, Principles of Polymer Chemistry, Cornell University Press, New York 1953 (at this time cited by 36241 according to Google Scholar).

Usually, the first extraction can remove most impurities, while the second extraction further improves the purity of the target substance. By repeatedly extracting, the target substance can be effectively separated and impurities removed, resulting in a pure extract.

Hi Piyali Mukherjee

Depending on the polymer, you could approximate the density to 1g/ml and with the volume of your box (6^3 nm^3) calculate the mass and then the amount of water molecules.

ICT species can form in nonpolar solvents if the molecule has a suitable donor-acceptor structure, even though they might be more stabilized in polar solvents. The formation of ICT states is mainly determined by the molecule's intrinsic properties rather than the solvent polarity.

The dielectric constant tells us how well a solvent can decrease the force between charged particles. Basically, a high dielectric constant means the solvent is really good at pulling ions apart, which usually makes it easier for salts to dissolve in it. Water is a prime example—it has a high dielectric constant, making it excellent for dissolving many salts.

But, the story doesn't end there. Several other factors play into how well a salt dissolves:

For NaCl and similar salts, water's super high dielectric constant plus its knack for forming strong hydrogen bonds make it especially good at dissolving salts. Adding another solvent into the mix, whether it's formamide (which has a different way of bonding despite its high dielectric constant) or ethanol (which has a lower dielectric constant and isn't as good at stabilizing ions), tends to mess up the delicate balance that makes water so effective on its own, usually making the salt less soluble.

The fact that no added solvent makes NaCl more soluble than it is in pure water highlights how uniquely suited water is for dissolving ionic compounds like salts.

Thank you Phil Käding ! I performed yesterday the reaction in an extremely dried system and the quantity of the brown impurities was less than the first time.

Please share any research or review article supporting the answer When synthesizing nanoparticles, what is the reason for centrifugation using ethanol

You're right, adding ammonium sulfate could potentially quaternize the tertiary amine groups in your polymer, which could affect the properties of your anionic exchange membrane. If you're concerned about altering the chemical nature of the polymer, it's best to avoid using salts that could react with it.

In that case, you might want to focus on solvent-based methods for precipitation. You could try experimenting with different solvent mixtures or adjusting the temperature of your solutions to see if that helps with the precipitation without chemically altering your polymer.

Dear all, in some situations yes, the urethane linkage is prone to hydrolytic scission. It is possible that the solvents are not dry enough. There are many factors influencing such hydrolytic chain degradation reaction. My regards

For polyolefin elastomers (PO), appropriate organic solvents are typically non-polar, such as hexane, toluene, and xylene.

No, the water will must have electrolits, actually a little more than the usual because alcohol will dehydrate the rats

Polyphthalamide (PPA) is an engineering thermoplastic with exceptional properties, including thermal stability, mechanical strength, and chemical resistance. These characteristics make PPA a preferred choice in demanding industries such as automotive, electronics, and aerospace. However, the robustness that makes PPA valuable also poses challenges for dissolution, which is essential for various applications.

The solubility issue with PPA is rooted in its chemical structure, which consists of aromatic rings connected by amide bonds. This structure enhances PPA's performance but also makes it resistant to dissolution due to the rigid polymer chains and strong intermolecular interactions, including hydrogen bonding. To find an effective solvent, the principle of 'like dissolves like' is followed, which requires a solvent that can match or disrupt PPA's polar nature.

Solvent exploration has included formic acid, DMSO, alcohol-based solutions, and toluene. Each solvent is chosen based on its interaction with the polymer. For instance, formic acid dissolves certain polyamides by forming hydrogen bonds with amide groups. However, it is not effective with PPA due to the polymer's structural rigidity and aromaticity. Similarly, although DMSO is a powerful solvent for many compounds, it is not effective for dissolving PPA due to its strong intermolecular forces.

Therefore, more aggressive solvent systems such as sulfuric acid, methanesulfonic acid, and trifluoroacetic acid have been considered. These solvents provide the necessary acidic environment to disrupt hydrogen bonding in PPA, which may facilitate its dissolution. However, the use of corrosive substances necessitates careful handling and consideration of safety and environmental impacts.

To dissolve PPA effectively, optimize various experimental parameters, including temperature, time, solvent-to-polymer ratio, and mechanical agitation. These factors play crucial roles in facilitating the solvent's penetration into the polymer matrix and promoting the dissolution process.

In conclusion, dissolving polyphthalamide is a complex challenge that requires balancing solvent efficacy with safety considerations. Exploring aggressive solvent systems under controlled conditions offers a promising approach to overcoming the solubility barriers posed by PPA's robust chemical structure. This ongoing quest highlights the intricate interplay between polymer chemistry and solvent science, driving innovation in material processing and application.

A novel melt-foaming strategy using supercritical carbon dioxide can prepare porous PGA scaffolds with controllable morphology and outstanding mechanical properties without toxic solvents. Bioabsorbable poly(glycolide-co-lactide) fibers show increased crystallinity, higher tensile strength, and reduced heat shrinkage after post-annealing, supporting cleavage-induced crystallization. Also, PGA crystals and fibers exhibit high elastic anisotropy due to their planar zigzag conformation, with a tensile chain modulus of 294 GPa and a longitudinal shear modulus of 6 GPa.

Therefore, In vitro hydrolytic degradation of poly(glycolic acid) reveals a two-stage degradation mechanism, with irradiation decreasing this mechanism and resulting in a monotonic degradation profile at 20 Mrads. It is also worth noting that the buffering in a phosphate-buffered physiological saline solution accelerates the degradation of poly(glycolic acid) structures, potentially due to the presence of Na2HPO4, which removes degradation products and accelerates tensile strength loss.

Please see this researches that might be useful:

· Novel fabricating process for porous polyglycolic acid scaffolds by melt-foaming using supercritical carbon dioxide, ACS Biomaterials Science & Engineering, 2017. DOI: 10.1021/acsbiomaterials.7b00692

Best regards,

Fatemeh Bagherzadeh The issues in your nanostructure synthesis process may stem from the choice of solvents and drug loading efficiency. Specifically, the low solubility of Doxycycline monohydrate in water during acid-base extraction and the heterogeneity observed in the micelle size (as indicated by two peaks in DLS data) could be contributing factors.

Ethanol is commonly used for micelle preparation, but it should not negatively affect drug stability or micelle formation. Consider optimizing solvent selection and micelle formation to improve your results.

The travelling distance will depend on their partition coeeficients. More the polarity, less will be the travel distance. Now you have to compare among your tested compounds, which one is more polar

Dear Akram A. Albaidhani, ethanol is the most used solvent. If you use soxhlet extractor, concentration is meaningless, rather the number of cycles is. My Regards

Diethyl ether and pentane both is very easy to evaporate even at cold temperatures cause the boiling point at atm pressure is 35/36°C.

There are a lot of tables where you can look up the temperature/pressure relationship for evaporation. From an educated guess I would start at ~650 mbar when using a water bath with rt. If you want to be sure you can start even higher and go down by 50 mbar steps. Good luck.

You could try measuring the antibacterial activity of trace concentrations of the solvent under the same conditions. If you also can get a measurement of the solvent concentration in the sample (talk to an analytical chemist about that), you would then be able to tell whether the amount of solvent present in the sample is sufficient to account for the antibacterial effect of the extract.

You might be able to precipitate the DCU from cold ethyl acetate, cold diethyl ether or toluene.

You could also replace DCC by EDC as the corresponding urea is soluble in acidic aqueous.

What kind of palladium catalyst are you using? I have seen great difference between Pd(PPh4)3 vs PdCl2, for example.

For example, if you want to prepare a 0.1 M TiO2 solution and your powder is in gram, Weigh out the desired amount of TiO2 powder (e.g., 0.1 grams). Determine the volume of solvent needed to achieve 0.1 M concentration (e.g., 1 liter for 0.1 M solution). Dissolve the 0.1 grams of TiO2 powder in the 1 liter of solvent. Stir or sonicate the solution until the TiO2 powder is completely dissolved.

As for the solvent choice, it depends on the specific requirements of your fungal medium and experimental setup. Water is a commonly used solvent for preparing TiO2 solutions for biological applications due to its compatibility with many biological systems. However, if your fungal medium requires a different solvent, ensure that the solvent is compatible with both the medium and TiO2. Always consider any potential interactions between the solvent and TiO2, as well as any effects on the biological system you are studying.

When performing Gaussian calculations for a molecule in different phases (e.g., gas and solvent) or different states (neutral, anion, or cation), the optimization strategy may vary based on your specific goals.

It's generally a good practice to iteratively refine your calculations based on the obtained results. Keep in mind that the choice of basis set, level of theory, and the solvent model can significantly impact the accuracy of your calculations. Always validate your results against experimental data when available and consider the specific requirements of your research or study.

Dear Jennivee Chua ! Freeze drying can be done by yourself without complicated equipment. To do this, you need a vacuum pump, a sample vessel, a trap for water and alcohol, and an ordinary thermos.

Prepare a mixture of ice and salt, put it in a thermos, and a vessel with a sample in the same place so that it cools down. Then take out the vessel. You put a trap in a thermos. Connects the vessel to the trap and the vacuum pump. Pumping out the air. If everything is sealed and the vacuum has turned out, then turn off the tap on the vacuum pump. In this case, during the evaporation of water, the sample will freeze and water and alcohol will sublimate into a trap. It is only necessary to change the cooling mixture of ice and salt. It will turn out to be a cryogel.

9M sulphuric acid

The choice of the best organic solvent for solubility and extraction of nitrophenols depends on several factors, including the specific nitrophenol compound, the desired extraction efficiency, and the intended application. However, some commonly used organic solvents for the solubility and extraction of nitrophenols include:

The choice of solvent should be based on the specific requirements of your extraction process, including the polarity of the nitrophenol compound, the desired selectivity, and the safety considerations associated with the solvent.

@Risna Ramadhani You can go with the same solvent which is used for the extraction of plant material.

Hope it"ll help.

Thanks

You may use toluene/methanol mixture as an eluent if your sample is too hydrophobic to be dissolved in polar solvents you listed.

Biodiesel analysis of microalgal cultures using GC analysis are well documented. Try a keyword search on the web to find thousands of example methods, procedures, white papers, application notes etc for review. *Learning how to research a question on your own is one of the most important skills you can learn.

Consult a local professional chromatographer for hands-on help developing methods and running samples (to insure the methods and techniques used are appropriate and follow good chromatography fundamentals).

1. Methyl acetate as a solvent and 0.1 equivalent of AIBN as catalyst at 60 oC

2. ACN as a solvent rest conditions are same.

Hi,

If you mix (if it's your case) pure methanol from one line with for example buffer from another line it may happen. The best solution is to mix organic solvent with some part of the water buffer (20% buffer in solution for example) then if you follow the steps below system should work.

Positioning of the Solvent Reservoir: Ensure that the solvent reservoir is always higher than the pump to minimize bubble formation

Degassing the Solvent: Before introducing the solvent to the HPLC system, you can degas the solvent by methods such as sonicating, sparging with nitrogen gas for 30 minutes, or vacuum filtration (sometimes the best way is to use all)

Filtering the Mobile Phase: Use filters with larger pore sizes if the flow rate is too high for the pore size of the filter, as this can prevent bubble formation

Other Considerations: It's also important to check for any blockages or microbial growth in the water line and to ensure that the buffers are fully soluble in the mobile phase when switching them. Never mix the final solvent solution in the solvent reservoir (without filtration)

Hope it helps,

Tomasz

Thank you so much professor Emanuel cooper ,it really worked for me.@Emanuel

Colin Varghese, Yes, you can substitute EG for DEG in your microwave-assisted polyol synthesis.

DImethyl sulfoxide, dimethylformamide or amide solvents

I prepare in deionizated water at the concentration of 600mM, because the solubility is near it (I think it is 660mM) and then I filter the solution to sterilize, because I think it degrades in autoclave. I use the final concentration of 20mM and it is not toxic and improves the growth in oxidative stress conditions, but other people already saw this effect at less concentrations, like 10mM.

If adding water to the IPA solution makes it transparent, it's possible that the polymer may have re-dissolved in the water due to the change in solvent conditions. In that case, you can try adding a different non-solvent that is less miscible with water, such as a different organic solvent like hexane or diethyl ether. This may help to induce precipitation of the polymer from the solution.

Separating a ruthenium complex from its ligand, especially when they have similar solubilities, can be challenging. Here are a few strategies you can try:

Column Chromatography Optimization:

Experiment with different column chromatography conditions, such as changing the stationary phase, using a different elution solvent system, or adjusting the polarity of the solvent.

Solvent Gradient Elution:Employ a gradient elution strategy during column chromatography. This involves starting with a more polar solvent and gradually increasing the polarity, which may help in better separating the ruthenium complex from the 1H-imidazole.

Reversed-Phase Chromatography:Consider using reversed-phase chromatography, especially if your complex is hydrophilic. This technique can exploit differences in hydrophobicity for separation.Size-Exclusion Chromatography:

Size-exclusion chromatography separates molecules based on size. If your ruthenium complex and 1H-imidazole have significant differences in size, this method might be effective.

Recrystallization:Attempt recrystallization using a suitable solvent system. Sometimes, complexes can be encouraged to crystallize separately from their ligands.Selective Precipitation:

Investigate the possibility of selective precipitation by adding a non-solvent or changing the solvent conditions to encourage the separation of the ruthenium complex from 1H-imidazole.

Extraction:Explore liquid-liquid extraction using an immiscible solvent that selectively extracts one component. This method might require optimization of conditions.

pH Adjustment:Evaluate the impact of pH on the solubility of the complex and the ligand. Adjusting the pH may alter the solubility of one of the components, aiding in separation.

Begin Initial Degassing with a lower temperature (around 50-100°C) for several hours to remove adsorbed moisture. This is particularly important if water from the synthesis process is present.

Solvent Removal: Gradually increase the temperature to remove any remaining solvent residues. Consider a temperature range of 100-150°C for several hours to eliminate chloroform and methanol.

Intermediate and Final Degassing: Continue the degassing process at intermediate temperatures (150-200°C) and, if needed, higher temperatures (250-350°C) for several hours to ensure complete removal of volatile compounds.

Always monitor the weight loss during degassing, and be cautious not to exceed the thermal stability of the organic cage material.

The absolute quantum yield of a fluorophore material typically remains constant with changes in concentration within a solution, assuming other conditions like temperature and solvent remain consistent. However, in some cases, there might be concentration-dependent quenching or aggregation effects that could affect fluorescence properties.

The observed changes in absolute quantum yield with varying concentration and solvent suggest potential aggregation effects, which can influence fluorescence properties. Consider using different techniques or instruments to validate your results, such as steady-state and time-resolved fluorescence spectroscopy. Additionally, ensuring proper sample preparation and accounting for any artifacts in measurements can enhance result accuracy.

I'm adding the answer to this question for future reference:

You don't need to prepare a phenol solution, and you definitely shouldn't dissolve phenol in water! You simply add the stoichiometry amount of solid phenol to 1,1,2,2-tetrachloroethane, and heat the mixture to a temperature of around 60-70 Celcius while stirring, then wait a few minutes until you have a clear solution with no apparent traces of undissolved phenol.

Hi Hassna Belhaj

You may have poor heat transfer from the hot plate to the aluminum bottle (depends a lot on the shape of the bottom of the bottle). The bottle should be immersed at least part-way into a heating medium that has a minimal vapor pressure, such as aluminum balls, a molten salt or a very low vapor pressure oil. That's if you feel you must work inside the glove box. Alternatively - and I would prefer this - you can wrap the bottle in an insulated electrical heating tape with voltage control; but you may want to do a similar experiment outside the glove box with a similar aluminum bottle to see if you reach the right temperature range.

If you're confident the bottle is hermetically closed, you may be able to do the heating outside the glove box, using an oil bath or even (gasp!) a water bath.

Sorry I cannot read your language, but really want to know how to make it more soluble in dmf. You suggest using eg. Dichloromethane. How much to add and to what setup use it?