HCL in a mobile phase

[gincot]

Is it possible to use a mobil phase containing HCL 0.0003N on an HLPC MSMS.

My mobil phase A is ACN 99%:water 1%:0.1% formic acid:2mM ammonium formate, B is ACN 30%:water 70%:0.1% formic acid:2mM ammonium formate. I want to add HCL 0.0003N to both of them. The pH is still within the recommended range

My concern is the stainless and the MSMS.

I am using an HILIC column and my samples contain HCL 0.0003N. This column is very hard to stabilise so I want to use a mobile phase that is the closer to the samples.

Thank you

[grzesiek]

have you already injected your samples to a system with mobile phase without HCL? do you see any problems? peak shape?

[HW Mueller]

Generally one modifies the sample solvent to match the mobile phase (if necessary), not the other way around, as one doesn´t want to change the chromatography when samples of different matrix are to be analyzed.
In my experience the damage done by HCl on stainless steel is dependend on its concentration, the mentioned concentration would probably attack quite slowly, if HCl were really present. You did not tell us what your mobile phase pH is, Cl- in basic solution does not seem to do anything. If it is acidic I wouldn´t add any HCl, especially since this doesn´t make any sense.

[gincot]

My problem is that the standards are sold in a 0.003N HCL solution. So every standards dilution are done with 0.003N HCL. This is the only way known to me to keep the molecules stable.

But in the end the final dilution is done with 10% of the standard in 0.003N HCL and 90% of the mobil phase A, resulting in a 0.0003N HCL solution in mobil phase A.

I have to keep a high ACN percentage for the chromatography and to be able to to redisolv my sample I only use 100ul of 0.003N HCL and 900 ul phase mobil A. Anything higher content in water with ruin the chromatography.

The range for my hilic column is 1-8 pH. I have mesured it and it is something around 3 but with a pH paper.

My biggest question is the quadripole, using ESI, the desolvation process will concentrate the HCL, but with the amont of gas in the source should I be concern.

For the HPLC, I figured, if I use the passivation technique it won't be harm

So I don't use HCL in my mobil phase right now because I was afraid but now I want to. It's hard to obtain stability with an HILIC colomn. I can already see slight variation with standards and I want to increase the amount injected so if I can match the sample with the mobil phase it will be best.

If there is any concern for the machine I will stop investigation and give higher limits.

[HW Mueller]

Well , you seem to have set up a chromatography, which means that your substance was stable enough in the mobile phase for the LC time scale. At around pH 3 you may have enough H+ and Cl- to lift the passivation or possibly get even further reaction. I know only that higher concentrations of H+ and Cl- (don´t remember exactly, maybe it was 0.1M) react with stainless steels, which I use, nearly instantaneously.
Others might have more specific info, or some advice on MS.

[Anthony_Ng]

Not sure if it is similar to the case of ICP-MS.

I remebered when I use acid digestion for heavy metal analysis, the final acid content is 20%. It is nitric acid but not HCl. Hence those high acid content samples are feed into ICP-MS to perform analysis.

I am not sure if MS of LC can deal with such high acid content, especially HCl.

[lmh]

given that you have a buffer much more concentrated than the amount of HCl you are planning to add, you're not really adding an acid, you're adding chloride ions. Unless you have a reason to believe that chloride, rather than pH, is what's relevant to the stability of your analyte or your assay, there's probably no point in doing this.

[gincot]

You are all making sens.

This HILIC column is freaking me out, it's so hard to stabilise

Thank you for bringing me back on earth

[Uwe Neue]

I am not convinced that your problem is the HCl in the sample. I bet it is the higher water content compared to the mobile phase. Do you really need to start with 99% acetonitrile? If possible, I would start with 95% acetonitrile, and things shoudl stabilize.

[Austin]

I've no experience on MS, but in LC, our lab avoids HCL in mobile phase, in the prevention of erosion, for ajusting pH, some alternative acids may be selected, such as formic acid, TFA.

[sam.pedraglio]

My biggest question is the quadripole, using ESI, the desolvation process will concentrate the HCL, but with the amont of gas in the source should I be concern.

I won't think to the quadrupole at all. Your ms vacuum system should remove the Cl-, if you work in pos mode, and the resultinh H+ is always the same regardless the acid you're working with.
The potentials acting on your ion transfer line should prevent neg ions to reach the quad.

[gincot]

When somebody uses HCl in the lab, all the stainless around after a few years become corroded and that's only with the vapors no contact with the acid. I don't undersand why in the source this could not happend.

[HW Mueller]

The corrosion due to HCl has been discussed extensively here, but I don´t recall whether the effect of pure HCl gas was included. So: Does anybody know/remember what sort of material is used for the transport of HCl gas?

[ThomasH]

In CE-MS we observed a lost of CE current when we used HCl to adjust our buffer pH.

Obviously Cl- was oxidized in ESI+ to Cl2. Hence you will produce Cl2 all the time....not the best choice!

[Bruce Hamilton]

The corrosion due to HCl has been discussed extensively here, but I don´t recall whether the effect of pure HCl gas was included. So: Does anybody know/remember what sort of material is used for the transport of HCl gas?

Anhydrous HCl is transported in mild steel cylinders, and industrial plumbing is thick-walled black iron pipe. Stainless steel can also be used. The corrosion issues with hydrogen chloride only arise when moisture is present - anhydrous is noncorrosive to many metals, but once it become hydrochloric acid .... .

Personally, I would avoid using it in a HPLC separation unless essential, and I would probably want to clean and repassivate the HPLC system after use to try and prevent future crevice corrosion initiation by residual chloride ions bound to metal surfaces.

Please keep having fun,

Bruce Hamilton