How can I prepare a phosphate buffer 50mmol-1, pH 4? just 200ml. Any help?

Does the pressure(-600 mmHg) affects pH?

When I conducted the degassing experiment using decompression under anaerobic condition(and I used ferrous based chelating agent), the oxidized ferric were observerd. So, could you tell me the...

03 March 2021 4,892 5 View

How optimize the Size Exclusion Chromatography?

Hello! I'll do a size exclusion chromatography, but I only have an open column, and I'll perform the peptide extraction from yeast, using buffer lysis (sodium phosphate 50 mM/NaCl 30 mM/DNAse and...

01 March 2021 2,215 2 View

Precipitate after adding laemmli buffer to protein solution containing Potassium Acetate?

Hi, I am running a size exclusion chromatography experiment with a buffer containing Potassium Acetate as a salt. I analyse these fractions through SDS-PAGE. After boiling my SEC fractions in...

01 March 2021 2,622 3 View

Which database would give me this list of chemical components?

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26 February 2021 5,525 3 View

Why is NH4OH added in heavy metals limit test?

The limit test I'm referring to is USP method II. In this procedure you need to dropwise add 6N of NH4OH to the sample until it the pH is alkali. After that you need to dilute and add HOAc until...

23 February 2021 2,049 3 View

Is there an ideal incubation time of RGO-modified SPCE before subsequent use, i.e., electrochemical characterization or further modification?

I notice that upon washing and air-drying of my RGO/SPCE surface and characterizing again via DPV, the current response towards ferricyanide probe significantly decreases. My worry is that the...

22 February 2021 5,324 3 View

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22 February 2021 9,932 11 View

How to prepare electrolyte of NaClO4 salt for Na-ion battery? Any problem with this salt?

Hello, I am trying to make anode for Na-ion batteries. I have no experience with preparation of the electrolyte for any batteries. NaClO4 salt are available and I am planning to use EC:PC as...

21 February 2021 8,132 1 View

Can anyone help or comment on solubilising chlorobutanol in aqueous injections in minimum time possible?

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21 February 2021 7,397 1 View

What reaction will occur when adding hexamine into ammonium nitrate in an acidic medium?

Hello, I am investigating properties of water in oil emulsion explosives. And adding hexamine (hexamethylenetetramine) into one of the phases that are used to make the emulsion should increase the...

21 February 2021 8,680 1 View

Adam B Shapiro

I would not recommend using phosphate as a buffer for pH 4. It does not have a pKa near 4. Citrate would be a better choice.

If you have access to a pH meter, first calibrate it with pH 4 standard buffer, then you can add 50 mM trisodium citrate dropwise to 200 mL of 50 mM citric acid in a beaker while mixing with a magnetic stirrer until the pH is 4.