Analysis of 0.1M H3PO4 and 0.5N NaOH extracts by 7800

Hello, we perform extractables testing at my lab and we have an upcoming study of single-use thermoplastic elastomer tubing which will be extracted in the following solvents: water, 0.1M H3PO4 and 0.5N NaOH. I am obviously not concerned about running the water sample, but what other sample prep/instrument setup steps should I consider with the other two extracts? I have a 7800 with an SPS4 autosampler, quartz Scott-type double pass spray chamber and micromist nebulizer. I typically run acid extracts/digests of HNO3/HCl and I am unfamiliar with running other solvents on this system and do not want to harm the instrument. Thank you for your help!

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  • Hi ,

     

    The problem is the NaOH. That leaches out the glassware. However, if the concertation is low then there is no big leaching effect and no problem and you can measure with the same sample intro setup, but another set of glassware.

    So one set of glassware (nebulizer, spraychamber, transfer tube, torch) for the HNO3/HCl samples and one set for the Basic solution. this give the best stability for both analysis.

    If you want to measure elements like Na, Si and B in the basic solution then you need the pfa spraychamber and torch setup.

  • Hi,

    Thank you for this info! I will order another set of glassware for the NaOH analyses. Can standards be prepared in NaOH for the NaOH extract analysis? I'm not sure of the stability of metals in NaOH. Do I need to treat the NaOH samples and standards with anything first or can I analyze them neat? I'm worried about preparing my standards in the usual 2% HNO3/0.5% HCl that I typically run and then analyzing NaOH extracts within that same sequence. 

  • Hi,

     

    there are many approches possible. The basic extracts could run directly (like suggested above), it could be diluted with water or it could be diluted with an acid. All these considerations are related with the stability of he elements in the liquid phase and the stability in the sample intro of the icpms. If the stability of the elements of interest are not good in the undiluted basic solution maybe a dilution with an acid to go to a lower pH could be consider. Only disadvantage is the detection limit rises with this dilution step. But the positive point is that a different set of sample intro isn't needed anymore if the measurement stay in acidified conditions.

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  • Hi,

     

    there are many approches possible. The basic extracts could run directly (like suggested above), it could be diluted with water or it could be diluted with an acid. All these considerations are related with the stability of he elements in the liquid phase and the stability in the sample intro of the icpms. If the stability of the elements of interest are not good in the undiluted basic solution maybe a dilution with an acid to go to a lower pH could be consider. Only disadvantage is the detection limit rises with this dilution step. But the positive point is that a different set of sample intro isn't needed anymore if the measurement stay in acidified conditions.

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