pH - Science topic

Hi everybody,

I have tried to make my home-made master mix for our laboratory. I have used two type of dyes , cresol red and Bromophenol Blue(BPB). I see when I use BPB my PCR is inhibited but no inhibition is observed for cresol red.

Have anyone had the same experience? Do you think the pH of BPB need to be adjusted before use? when I add BPB to my colourless master mix in the proper concentraion it return to blue so I think pH readjustment of master mix buffer is not needed. How do you think ?

Hi all,

I'm working on some acid-mediated sol-gel syntheses to make metal oxides. I have a few formulations working using only acetic acid, and metal-alkoxide precursors. However for some formulations, I need a pH lower than acetic acid can achieve alone and I'm unsure what alternatives to look for

Using fluorinated analogs of acetic (trifluoroacetic) did successfully work to lower the pH of the sol-gel and form smaller clusters, but also formed metal-fluoride species in the final products

Using formic acid appeared to work, but caused precipitation later on (too polar).

So basically I'm looking for an organic or mostly-organic acid to mix into acetic acid, to lower the solution pH without forming metal salts as a byproduct. Any suggestions?

Hello!

I am doing batch adsorption studies for removal of lead. I am using lead nitrate salt for this purpose. When I adjust the initial pH of solution to 5 or above it precipitates. However, in literature researchers reported initial pH of solution to 9 as well performing batch adsorption studies. Is because of salt or something else?

Thanks for your guidance.

Currently TBHP/FF6 M redox initiator is used in my latex polymerization. The by product of TBHP is VOC. Any recommendation for initiators of which by-products are not VOC or grafted to the end of polymer molecules? My reaction conditions: 70-90C, pH 4-6; styrene/acrylic polymer latex. Thermal or redox initialization will be fine. Hopefully, the peroxide is easy to handle.

Thanks!

Jake

Hello. In our laboratory, we have a non-refillable electrode, but its KCl level has decreased, and now we want to add an electrolyte solution. However, there isn't any hole. Can we make a hole?

Dear researchers

How to prepare buffer solution with pH of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 using NaH2PO4 and Na2HPO4?

Should we use NaOH and HCl?

Is it true To obtain a 20 mM Tris-HCl pH 7.4 solution, I just need to dilute 2 mL of 1 M Tris-HCl pH 7.4 to 98 mL of nuclease-free water (Total Volume 100mL)

I just want to make sure

Just wondering if anyone has any experience in setting up a Getinge mini bioreactor? More specifically, autoclaving the reactor, the gel pH sensor, and the dO2 sensor.

I am having trouble understanding how to use the pH probe and "pressurize" in the autoclave before first use. The pH probe has a lifecycle of 10-15 autoclaves. Would I have to bathe the probe in ethanol as a method of sterilizing the probe between cell cultures?

Any advice is welcomed! Thanks so much in advance!

I'm a beginner in ITC, does anyone have an idea why when measuring the heat of dilution and in measuring the interaction of HSA with the drug or even with the buffer itself, the curve goes up? HSA measurement at HEPES pH 7.4 and pH 6 give similar results. Different buffer concentrations and different ionic strength do not solve the problem...

We know pH range in water body is 0 to 14. 7 is neutral pH.

how to prepare 0.02 M sodium phosphate buffer (containing 6 mM NaCl, pH 6.9)

I want to prepare mammalian cell culture grade Sodium bicarbonate(SBC) solution from powder available in media kitchen for regular use.

Can i make it this way?

1. Dissolving SBC powder.

2. Filtering by 0.22um filter

3. pH adjustment

4. Sterilization by autoclaving

Does autoclaving degrade SBC?

Does pH will change after autoclaving?

At our lab we are trying to develop new dyes for different applications, and we need information about the stomach acidity of Galleria mellonella model.

I know P fixation in soils depend on many factors. For know there are general data sets for the % P fixation in relation to pH. I was wondering if there is something like this bu in retation to soil type.

I made a buffer solution dissolving 79 g of NaH2PO4.2H2O in 1000 mL DI water. Then tried to adjust the solution pH to 6.0 using HCl or NaOH. Initial pH was below 6, so I added NaOH into the solution. It started increasing the pH gradually, and solution pH came to 5.3. Then I added more NaOH (drop by drop and stirred thoroughly for a good amount of time) but pH was constant at 5.3 for quite some time. Then suddenly it jumped to 7.02. After that, I added HCl (drop by drop and stirred thoroughly) to decrease the pH, but nothing happened. pH was constant at 7.02 for a long time, then suddenly dropped to 5.3. Tried several times but pH jumps between 5.3 to 7.02 and vice versa. I can't seem to find any pH level between these two values. What should I do?

I tried glycine buffer but the yeast cells acidify the buffer so the pH goes down to 7-6 overnight. I need something that will stay around 9 and that isn't toxic to the cells.

I am planning to study adsorption efficiency of dye at different pH. As we know, some dyes would change colour at different pH. Therefore, is it necessary to plot different calibration curve at each pH? 7 different pH with 4 different dye concentrations would mean 28 solutions that have to be made. Is this a common approach?

The point of zero charge (pHpzc) indicates in which pH the adsorbent and adsorbate prefer to adsorb each other. At this pH, the number of positive charges are equal to the number of negative charges. To evaluate the pHpzc, 0.03 g of the adsorbent (PTA@MIL–53 (Fe)) was added to each 10 different 60 mL beakers containing 0.1 M KNO3 solution. HCl (1.0 N) as a strong acid and NaOH (1.0 N) as a strong base were applied to adjust the initial pH of each beaker (pHi) between 2–11. The samples were stirred for 24 hrs to get equilibrated and then the final pH values (pHf) correspond to the pH at which there is no net OH− or H+ adsorption, were measured. Then the diagram of pHi–pHf was plotted versus pHi. As depicted in Figure 5.8, the pHpzc was found to be 4.3 which was obtained from the intersection between the sketched curve and horizontal axis.

Hello, I want to do EMSA with native PAGE to check protein-dna interactions.

The PIs of my proteins are between 8.1-8.5. I know that the pH of my buffer must be higher, so that the net charge is negative and the protein goes "downwards" to the anode. But do I have to adjust the pH (e.g. let's say 9.5) of everything? So separating gel, running buffer and loading dye? Or is the gel enough? I cannot find anything about running buffer and loading dye.

I my group we only did discontinous native gels so far, but in all recipes the pH of the stacking gel is around 6.8. Then my protein would run out of the gel, wouldn't it? Can I also change the pH of the stacking gel without changing the purpose of the stacking gel? I also found continuous native gels on the internet. Does that really work without getting a big smear?

Does anyone knows the pH acceptable range for virus transport medium (VTM) for Sars cov 2 samples? I supose that it depends if you are only testing by PCR or if you need viability for culture but does anyone has experience in this subject?

Found a studie that defends that in normal individuals with no history of reflux or eustachian tube dysfunction, the pH values range from 6.10 to 7.92 with an average pH of 7.03 (SD, 0.67) so i believe that VTM should be buffered around pH 7 (with a variation of plus or minus 1) but need to confirm that.

Thank you and be safe.

I am trying to extract DNA from serum. I found an article that claimed simple extraction can be done in a single tube -

Here they used a solution containing 6M NaI/13mM EDTA/0.5% sodium N-lauroylsarcosine/10 µg glycogen as a carrier/26mM Tris-HCl, pH 8.

But currently, I don't have NaI and glycogen. So, I am thinking of making a solution with KI + EDTA + sodium lauroyl sulfate + Tris-HCl, pH 8. And finally, use Na-acetate and absolute ethanol for the precipitation of DNA.

What consideration should I take into account to use alternative reagents?

And, in their protocol does it mean the final solution containing all reagent should have a pH 8 or it just means the use of Tris-HCL with pH 8?

I already did some activation experiment to observe expression of CD40, CD86, CD80 and MHC with macrophage 264.7 and dendritic cells (DC2.4). I treat these cells with positive control LPS and therapeutic nanoparticles or bare nanoparticles. So, once I collected the cells, washed them and fixed with 4% paraformaldehyde (pH=6.9) or 5% Formalin in PBS. But I observed that I was losing cells with washing, fixing and post-fixing washing steps. My events/second in the flow cytometry were very low. I was thinking what if I don't fix the cells and I was wondering what was the purpose of fixing?? If I don't fix the cells, should that affect the results negatively? Thanks

I am conducting the preliminary in vitro anti-inflammatory study on my plant sample using the BSA denaturation assay. My reaction mixture is 250ul BSA (4% w/v in PBS), 750ul PBS (pH 6.4) and 500ul Sample. The concentrations of my sample are in the range of 100ug/ml, 200ug/ml, 300ug/ml, and 500ug/ml. The absorbance was read at 660 nm. However, the OD for my Control is lower than that of my Samples, and the OD gradually increased with the increase in concentration.

This resulted in negative values for my inhibition percentage.

The formula I used is %inhibition=(Abs Control - Abs Sample)/Abs Control *100

Can anyone suggest to me what I might be doing wrong, and how can I overcome the problem

Numerous studies have reported the positive effects of hydrogen-rich water (HRW) on various physiological parameters, leading to multiple health benefits. Additionally, HRW has shown to be highly efficient in extracting various components from plants, such as phenolics, flavonoids, antioxidants, anthocyanins, pigments, and more.

One of the reasons behind HRW's different activities is believed to be the modification of the physical and chemical structure of water by dissolved hydrogen. In simpler terms, the question arises: Does dissolved hydrogen in water affect hydrogen bonds, and if so, how does this effect behave with respect to the pH value?

Thanks

Dear all,

I am looking for guidance relating to a formula to calculate mass of reagents based on the desired pH and molarity. Is there a formula for this?

I am looking to create, and justify with calculations, a phosphate buffer. I am intending to create phosphate buffers 0.1 M pH 6.0 and 0.2 M pH 6.8.

Thank you in advance for any guidance :)

Kieran

I’m currently using a protein (36 kDa) which needs to be unfolded during a labelling reaction. unfortunately the protein precipitates completely upon denaturation with EDTA which chelates the zinc ions holding its structure together. I’ve tried the reaction at 37, 40, and 55 degrees Celsius all with the same issue.

The exact same protocol (37 degrees, same edta:zinc ratio, time course) works for smaller constructs of the protein. I typically unfold, reduce, and then add the labelling reagent sequentially for 50 minutes each (total 2.5 hours shaking at 37). My protein concentrations have been between 20 and 200 micromolar, and the pH is maintained at 7.8 in 100 mM ammonium bicarbonate buffer (no salt) for optimal labelling.

I need the protein to remain in solution for downstream experiments after the labelling reaction. How can I denature the protein while keeping it soluble?

The protein pI is 7.06, which may be too close to the reaction buffer, especially considering that the other constructs had pi’s at 5.3 and 6.6. I’m considering testing a higher pH, unfolding with EDTA and a detergent, and increasing the salt concentration. Ideally I’d have as low a salt concentration as possible for downstream mass spec, and maintain the pH between 7.5 and 8.5 for optimal labelling with the different reagents. I’d appreciate any feedback or advice!

I can't find at what pH I have to adjust the CaCl2 solution. In my notes it's necessary 8.0 but i'm not sure

We prepared alginate beads 2% in CaCl2 200 mM, after stirring for 1h the beads were washed with water, and incubated with the substrate in the presence of 100 mM tartrate buffer pH 5.5 after 1h incubation we noticed huge weight loss of the beads

What are the differences between 50 mM glycine-hydrochloric acid buffer (pH 3) and 100 mM glycine-hydrochloric acid buffer (pH 3), especially regarding osmotic pressure? Why do they have the same pH value but different glycine concentrations.If I need to use it to wash cell , which concentration of glycine buffer is closer to isotonic, thereby ensuring cell survival?

I am planning to synthesize AgNP using plant extract as a bioreductor.

I have come across several papers recommending a neutral to alkaline pH range (pH 7-8) to achieve silver nanoparticles with characteristics such as small size (<100 nm), uniformity, and stability. In green synthesis approaches, is it acceptable to use chemical reagents to adjust the pH, or are there alternative methods available?"

I would greatly appreciate any insights or advice on these questions. Thank you in advance for your help.

Best regards,

I am planning to synthesize AgNP using plant extract as a bioreductor. In the green synthesis approaches of silver nanoparticles, should I focus solely on preventing the degradation temperature of reducing metabolites such as phenolic compounds?

I would greatly appreciate any insights or advice on these questions. Thank you in advance for your help.

Best regards,

Thanks in advance

hello ，I want to use exogenous ligands to activate receptors on the surface of the U87 cell line. How can I remove endogenous ligands before the experiment to ensure a low baseline receptor activation level? I tried treating the cells with a glycine buffer at pH 2.7 (30 seconds * 3 times), but after treatment, my cells died. How can I optimize my experimental conditions? thanks for your kindly help.

Besides extracting the poorly crystalline Fe- and Al-(hydroxy)oxides, does 0.2 (M) ammonium oxalate-oxalic acid (pH 3.25) buffer extract poorly crystalline Mn-oxides too?

Further, how does one calculate the pH of such a buffer solution? Using a pH meter is impossible due to the high viscosity of the buffer solution... Any chemists here?

I am attempting to perform an EMSA with a transcription factor and its wildtype binding sequence but the first attempt showed that the protein never left the well. After some research, I have discovered that the theoretical pI of the protein is approximately 8.8 and my running buffer is 8.3.

What is the best way to run an EMSA for this protein? I am worried that if I change the loading buffer pH that the protein:DNA binding might be affected. Can I just adjust the pH of the running buffer to 1 point above the protein's pI (e.g. 9.8) with NaOH? Do I need to adjust the pH of the gel as well?

Typical neutralization buffer used for Protein A/G affinity separations is 1 M Tris/HCl pH 9.0

Any alternate buffer for 1 M Tris/HCl ?

We want to simulate a protein-cabohydrate complex at various pH ranging from 6.8 to 7.4.

Can we do this on Gromacs?.

Do we have to simulate complex at different constant pH or the system will vary pH itself during simulation?

If simulating complex at various constant pH do we have to decide the protonation states of amino acids first then dock the carbohydrate?

Or can we decide the protonation states after docking?

Is there any alternative to Gromacs for this type of study?

The standard of different nutrients/metals has a pH between 2 to 4 and when we prepared the sample, sample had a pH between 5 to 7. When we ensure the pH of the sample is within the range of pH of standard use. We obtained different results as compared to non-adjusted results.

Can someone provide the literature regarding this issue? I have already studied the effect of pH but not relevant to the standard used. Thanks in advance

Could someone assist me, please? I'm seeking guidance on how to determine the pH value from a CV curve and convert Potential vs Ag/AgCl/KCl to pH measurements for a standard buffer solution using Optentiomentric analysis based on the CV results. Additionally, I would appreciate advice on how to ascertain pH sensing for an unknown solution utilizing a 3-electrode system (with the working electrode being GCE/Active material, reference electrode as Ag.AgCl/KCl, and counter electrode as Pt foil). Suggestions and answers supported by references would be greatly appreciated.

Hello everyone,

I need a citrate buffer with an optimal pH of 4.8 for the enzymes I'm working with. I'm using citric acid monohydrate (molecular weight: 210.14 g/mol) and adjusting the pH with NaOH. I'm preparing it as a 10x concentration and diluting it to 1x in the final volume (15-200 µl).

However, I've come across recipes for citrate buffer that use both sodium citrate and citric acid.

My question is whether the buffer I'm making will be strong enough to maintain a pH of 4.8 when I dilute it to 1x in my sample. Is the recipe with sodium citrate and citric acid a better option for buffering at pH 4.8?

Hi, I want to study the temperature and pH stability of lactoferrin, so I performed Circular Dichroism (CD) of lactoferrin at different pH (pH 1.2 and pH 2.0) and temperatures but observed no denaturation. Does anyone have idea if there is something that I am missing in my experiment?

Hello,

I need your support and suggestions. When I autoclave broth media and put them in my anaerobic cabinet to pre-reduce, the pH will drop of 0.5-1.0 (depending on the medium composition and its buffering capacity) due to the CO2 present in the gas mix that is dissolving and acidifying the media. What I've been doing so far is autoclave, then adjust the pH (as autoclaving can alter the pH too) in sterile conditions, considering the pH drop after pre-reduction with the CO2-containing gas mix. However, adjusting the pH in sterile conditions is not optimal as I need to open the bottle and take aliquots with the risk of contaminating my media. So the ideal would be to correct the pH before autoclaving, but I will need to take into consideration pH alteration by the sterilization cycle and pre-reduction.

Does any of you have any suggestion or tips to address this point?

Thank you very much!

One day when we made our regularly used medium, we noticed the initial pH was much higher than usual (above 6.0. usually it is around 4.0). It seems it only happened in our lab. The neighbor lab doesn't have problems. I have tried to test the initial pH using the water from our lab (B16) and the neighbor lab (B12). When I made LB medium, the initial pH was comparable with water from both labs; however, when making other media containing salts, vitamins, hormones, and sucrose, they showed different readings. The pH using water from neighbor lab was similar as our previous records while that using our lab was abnormally higher. I also used pH strips. The pH for water from the neighbor lab has been consistent, but that from our lab varied. Occasionally, it was similar; but most time shown in the attached file (shown in the attached file). Now my concern is what caused the high pH of this water. Is it toxic for our tissue culture? Any suggestions for figuring out the problem? Any information will be appreciated.

How can I convert the potential of reference electrode Hg/Hg₂Cl₂ to NHE? The electrolyte is 0.5 M Na₂SO₄ and the pH is 7 and the flat band was obtained from M-S plot. Is it same as Ag/AgCl ?

Usually equation used for Ag/AgCl is E_NHE​=E_Ag/AgCl​ + 0.197 + 0.059pH then what is it for Hg/Hg₂Cl₂

All my SDS Gels are having wave like thing and no prominent bands. I checked the pH of the buffers and they were optimum.

Mucilage has been isolated from a plant material by extraction with sodium carbonate solution and precipitating the same by change of pH to acidic condition.

What tests need to be done to determine the protein and corbohydrate content?

What are the economic methods for structure elucidation of same?

I have a PBS solution with pH= 7.40. The solution consists of Sodium chloride, monosodiumdihydrogen phosphate, and disodiumhydrogen phosphate. I want to determine both monosodiumdihydrogenphosphate and disodiumhydrogen phosphate potentiometrically using a pH electrode. Is that possible?

I attempted to dissolve 20 mM DTNB(5,5 - Dithiobis(2-nitrobenzoic acid) in 1X PBS buffer(0.1M pbs, pH 7.3), but it was unsuccessful.

Even after adding DTNB to the PBS buffer and vortexing for about 40 minutes, it did not dissolve. Then, I placed the DTNB-containing PBS buffer in a tumbler and reacted it for approximately 16 hours, but it still did not dissolve.

DTNB seems to be insoluble.....

Does anyone know a solution to this? I would appreciate any advice you may have.

According to Kokubo's instuction for preparing SBF (Simulated Body Fluid) pH should be increased from 2.0 to 7.4 after adding Tris to the solution. I added all additives one by one, and the pH became 1.8-1.9 right before adding Tris. But then after adding Tris it didn't increased.

Does it mean the Tris composition is wrong? or Should I consider something especial in adding Tris?

(The Kukobo's paper has been attached.)

Thank you so much in advance for your replies.

I have acetic acid glacial 100% GR solution

my sample has Cu, Cd, Zn, NaOH, and H2SO4. I expected to see cu precipitation at this pH.

I've been attempting to utilize Native PAGE to observe how my protein of interest, Hsp90, interacts with its cochaperones and clients within mouse embryonic stem cells (mESCs). I'm hoping to run quality Natives to determine and characterize the many complexes it is associated with, however after running several native gels and playing around with some of the conditions, I'm still not confident in how great they are because there seems to be a lot of streaking within the lanes especially on the sides (aligned along the walls of the well where sample loading occurred). I run whole cell lysate through, anywhere from 100-150ug of protein though I have loaded less. Using Native PAGE, I know not to expect great resolution, however I usually do see some well defined bands and my NativeMark runs through well. If streaking were to occur I would expect it to happen more uniformly across each lane and not just on the left and right side of the lane, leaving the middle seemingly unaffected?

If I could get any advice from someone that has experience running Native PAGE especially with lysates that would be greatly appreciated. If it helps my lysis buffer is 20mM HEPES pH 7.4, 50mM KCl, 2mM EDTA pH 8.0, and 0.01% NP-40. For making the acrylamide gel I utilize a Tris-HCl buffer at 0.375M pH 8.8 that I use to dilute 30% acrylamide to make a 4-15% gradient gel with a 3.25% stacking (my stock acrylamide is 30% Acrylamide/Bis solution 37.5:1 if that is important). The Native Sample Buffer I use to load is a 4x concentration (125mM Tris-HCl pH 6.8, 50% glycerol, 0.08% bromophenol blue) and the running buffer (10x) is essentially standard running buffer in the absence of SDS (0.25M Tris base, 1.92M glycine)

I've attached images of some of my Natives. The one with the fluorescent Western Blot was from cells transfected with mCherry-Hsp90 and blotted for mCherry.

I also have an undergrad that is attempting to work out a Blue Native PAGE protocol, but that too seems to have similar issues with side streaking along the well borders all the way down the gel. Again any help and advice would be appreciated!

Actually, I am trying to culture seaweeds inside lab for experimental purpose. I'm facing contamination in spore culture and also I can't get a proper growth response with juvenile algae. I m using commercial white fluorescent light, cotton filtered autoclave seawater, pH 7.8 with PES media in 5litre closed containers which having aeration from upside. I have a doubt that I need to do a cultures with opened containers or closed completely. Anyone pls tell me

The buffer contains: 100mM NaCI, 0.1% Triton X-100, 300mM Sucrose, 1mM MgC2, 1mM EGTA, 10mM PIPES (pH 6.8), and 100uM PMSF

When the pH turn low (acidification) in salty-marine water so what change of the Hemoglobin dissociation curve? Is respiratory frequency of a marine fish increase when pH turn low than normal?

Thank you at all!

Hi everbody,

Is there any method for pH stability test of an organic compounds except HPLC/MS and UPLC/MS?

Thanks

I'm purifying a recombinant protein. Currently, I use HIC to purify it. The specification of my Bind and Elution buffer is according to the following concentration, EC and pH...

Bind,

Sodium phosphate 30mM

EC 60

pH 7.5

Elation,

Sodium phosphate 5mM

EC 60

pH 8.5

When I washing the column with Elution buffer, impurities and som of my target proteins are removed. However, most of my target protein is removed during washing with water, where EC is reduced to less than 0.5 mS.

Here I'm looking for buffer preparation with EC less than 0.5mS. I will be very grateful if someone can help me to prepare this buffer.

I'm looking information about some experimental aspects on Drosophila melanogaster, is it possible to know the physiological pH of this study model?

I am running SDS page gels using the mini-PROTEAN tetra vertical tank. Gels ran normally up until about 3/4 of the way down the gel. At this point, the dye changes from blue to yellow and became distort. I have inspected the module so this is not the problem. The electrophoresis buffer used has the correct pH. The loading dye was Laemmli Loading Buffer. All gels were run at 140V for 50-60 minutes.

Hello every one

Can you please guide me on the hydrogeling method for decellularized skin?

It opens at room temperature and gels in the fridge. How can I convert it to a hydrogel at room temperature? Does it close at a certain pH because I set the pH at 7.4?

I am looking for answers as to whether NaHCO3 buffered cell culture media stored outside a CO2 gassed atmosphere changes it's pH irreversibly.

I understand how the NaHCO3 buffer principally works. But I wonder if the equilibrium between CO2 and HCO3- is reversible, always readjusting, depending on ambient temperature and CO2 gassing (+ atmospheric pressure)?

Suppose I would prepare a medium that is NaHCO3 buffered and has a pH = 7.3 after preparation in the lab (i.e., 20° C & 0.04% CO2). The pH was adjusted using HCL and NaOH. If I were to incubate this medium for 24 hours at 5% CO2, 37°C, and then remove it from the incubator, would the pH then return to 7.3 at the Lab-atmosphere?

This would be easy to prove experimentally and I will try this out in the next few days, but I would be interested to know if I might be missing something.

Emphasis on equations,temperature and pH

I am currently attempting to culture cell lines in a high %CO₂ incubator to mimic hypoxic conditions. Unfortunately we do not have incubators that can adjust the O₂, nor do I have access to a hypoxic chamber so increasing the CO₂ to 20% seems to be my only option.

The resulting issue: cell culture media typically contains a sodium bicarbonate buffering system that is optimised for incubators set between 5-10% CO₂, so in a 20% CO₂ incubator the media becomes slightly acidic.

Theoretically, I could increase in concentration of NaHCO₃ to 8g/L for 20% CO₂ to buffer the media to a pH of 7.4 (a reference for the calculation used to obtain this value https://www.researchgate.net/deref/https%3A%2F%2Ftools.thermofisher.com%2Fcontent%2Fsfs%2Fbrochures%2FD19558.pdf?_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InNpZ251cCIsInBhZ2UiOiJxdWVzdGlvbiIsInBvc2l0aW9uIjoicGFnZUNvbnRlbnQifX0), this however leads to changes in the osmolarity that my cell lines can't seem to handle.

Does anyone have any suggestions on how I could adjust my cell culture media to suitably culture cells in 20%CO₂?

I have access to tris-hydrochloride powder. Can I use that and adjust the ph using NaOH to make a solution of tris-Hcl (pH 8.5) rather than using Tris base? Thanks

The pH range of a borate-phosphate buffer solution can be taken as the range of the phosphate and borate buffers separately?

If you want to design a hydrophobic eutectic solvent as an extractant, how can you make it used for solvent extraction under acidic conditions? How should the extractant be modified to move its optimal extraction pH to the acidic range?

I have never used DOE. I want to perform optimization of three parameters that affect my experiment. The parameters are pH (9.0-11), concentration of Lm (5-100uM) and concentration of POV (5-200 ug/mL). I will gratefully appreciate it if someone can lend a helping hand. Thank you

Hi everyone,

I have expressed 6x histidine tagged protein(35kDa) and purified using Ni-NTA agarose (Qiagen). The elution buffer contain 20mM of Sodium phosphate, 500mM NaCl and 250mM Imidazole. I concentrated the eluted protein using amicon ultra centrifuge filter. 8 tubes of 500uL of eluted protein was concentrated and washed 5 times with 1xPBS pH 7.4 (500uL each). I measure the concentration of protein, the 260/280 ration was high which was 1.05 and 1.86. I used the purified protein to run ELISA and there was no signal at all (same as blank).

Any suggestions to improve the purity of protein (260/280) because I concern that imidazole is still there and effect the ELISA results.

How can i convert the potential of reference electrode Ag/AgCl to NHE? The electrolyte is 0.5 M Na2SO4 and the pH is 7. I want to understand method for Mott Schottky calculations. Many thanks for the help.

Hi, I have established a bioreactor parameters mammalian cell process with the following parameters:

Setpoint Deadband PID settings

1) pH- 7.0 0.1 1.0,5.0,1.0

2) DO- 60% 1 1.0,1.0,1.0

3) Stirer- 127 0

4) PO2 cascade with oxygen at (10ml/min)

5) pH cascade with base and (acid CO2 at 10ml/min)

The issue here is still the oxygen doesn't stop at the given setpoint and reaches around 120-180 % DO.

what can I do to maintain the DO to the specific setpoint. The total volume of reactor is 250ml and WV is 100ml.

The other issue here is the stirrer speed at what rpm I should be keeping it. Can we calculate the rpm of the stirrer according to the volume of the working volume of the reactor. Tip speed was calculated as- 0.0376m/s.

please let me know if more information are needed.

for antioxidant enzyme activity

Hi,

I am measuring the production of 4nitrophenol at 405nm for my enzyme assay.

In the neg control (buffer + substrate) and the enzyme reaction at pH 5.5, 6.5 I observe the absorbance initially increases,decreases and fluctuates . Why is this happening?

I have attached a copy of the pH6.5 timecourse.

Hello,

I am writing to request assistance in characterizing a mineral solution that I have developed, known to possess basic properties with a pH level of 14.

My objective is to gain a comprehensive understanding of its composition through detailed analysis.

Specifically, I am interested in identifying the elemental composition, molecular structure, and any additional properties that define its nature.

Does someone have any insights or recommendations on tests or analyses that could elucidate its properties.

Thank you very much.

How to check pH of PCR mastermix?

Dear All,

I have been using western blot for over two years now and I haven't seen anything like his. The protein ladder starts resolving in the stacking gel itself ( right below the well). I have used fresh buffers (0.5M Tris HCL 1.5M Tris HCL) and running buffer (Tris-Glycine 0.1%SDS). I used Spectra Broadband protein ladder from Thermo Fischer. Moreover, I tried using other protein ladders too, it gave me the same problem. The pH of all buffers is proper and I run for 60V in the stacking gel. Please suggest to me some points rectify the mistake I am making.

Hi all,

For context, I am conducting a stability study using an ADC material formulated in different buffer systems to screen for the optimal pH/buffer to use for the final drug formulation.

The test conditions are:

- T0: freshly prepared samples

- 25C: stored for 2W and 4W

- 40C: stored for 2W

Two pH levels were tested (pH 6.3 and pH 6.8).

At the test points (T0 and 2W) the samples were collected and frozen in -80C to perform the analysis altogether for all samples at 4W. 4W samples were also frozen for 2 hours prior to testing in order to give a uniform treatment for all the samples.

At 2W, all samples (25C and 40C) were similarly stable and comparable.

At 4W (25C), all samples except for one were comparatively stable and show similar patterns despite using different buffer systems or pH levels.

Usually, at 25C all samples remain stable even at Week 4. Severe changes are usually observed at the higher temperature and longer time point (ie. 40C, Week 4).

The analyses performed were:

> SEC-HPLC for monomer purity

> HIC-HPLC for DAR value

> CE-SDS (NR and R)

Appearance:

> The solution is clear and colorless, but there is a visible white agglomerate that seems to float around.

SEC-HPLC:

> The monomer peak area and height is visibly decreased, and several LMW peaks were observed (not present in the other samples). [attached a figure file]

HIC-HPLC:

> DAR4 peak is highly decreased (even lesser than the W2-40C sample), DAR2 peak appears very broad, plus the appearance of several low hydrophobicity peaks and a few peaks after the DAR4 peak which were not present in all of the other samples. [attached a figure file]

CE-SDS NR:

> 2H2L peak is decreased around 2-fold and 2H1L peak is increased 5-fold.

1) Based on the observation, is this phenomenon protein degradation or contamination?

2) How to prove either of these assumptions?

> I personally lean towards protein degradation, but some think it might be contamination.

3) Can anyone share any similar experiences and how you interpreted it?

I look forward to discussions and thanks in advance!