5 Peaks in DNPH blank. [August 19, 2004]
Posted: Sun Aug 29, 2004 8:18 pm
5 Peaks in DNPH blank.
Chromatography Forum: LC Message Board: 5 Peaks in DNPH blank.
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By Jaime on Thursday, August 19, 2004 - 06:16 am:
I analyzed glutaraldehyde by derivatizing with DNPH. Even though I have recrystallized the DNPH in acetonitrile/water I still get 5 peaks in my blank. one before the ACN peak and 3 after. My mobile phase is 60% ACN in 0.5% H3PO4. UV at 365nm.All peaks come out before the glutaraldehyde-DNPH peak. Column is Restek TO-11 at 35 C.
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By Consumer Products Guy on Thursday, August 19, 2004 - 07:41 am:
We assay glutaraldehyde in finished products using DNPH as well. We use deactivated C18 column at 365nm with ACN and H3PO4 as well (we use higher concentration of H3PO4). We obtain only the excess DNPH peak and the glutaraldehyde peak. Unfortunately, I'm not sure how to attach our chromatogram, it's in Word format.
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By Jaime on Thursday, August 19, 2004 - 10:56 am:
What brand is your DNPH powdered chemical?Who sells them?
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By Consumer Products Guy on Thursday, August 19, 2004 - 11:01 am:
Aldrich D19,930-1
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By Consumer Products Guy on Thursday, August 19, 2004 - 11:02 am:
Also Mallinckrodt #2412 (my sample is over 20 years old though)
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By HW Mueller on Thursday, August 19, 2004 - 11:48 pm:
Are you talking about dinitrophenylhydrazine?
If so, CP Guy, what reaction conditions are you using? The old H2SO4 method we used years ago produced a multitude of products which mostly emerged with the solvent front, luckily. (We had another problem, though, and gave up: Ascorbic acid produces two osazone geometric isomers which interconvert at a slightly slower rate than the chrom time span. Nevertheless a problem, which, however, should not occur here).
Oh yes, we had a peak appearing, sometimes, at various retention times, never got it under control. Have any of you seen this type of thing in this reaction?
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By Consumer Products Guy on Friday, August 20, 2004 - 07:52 am:
Yes, 2,4-dinitrophenylhydrazine; we've only used it for low levels of formaldehyde and glutaraldehyde, because those were the only aldehyde analytes of interest to my company. We haven't had any issues.
James R. Dahlgren and Melvin N. Jameson, “Determination of Formaldehyde and Other Aldehydes in Industrial Surfactants by Liquid Chromatographic Separation of Their Respective 2,4-Dinitrophenyl-hydrazone Derivatives,â€
Chromatography Forum: LC Message Board: 5 Peaks in DNPH blank.
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By Jaime on Thursday, August 19, 2004 - 06:16 am:
I analyzed glutaraldehyde by derivatizing with DNPH. Even though I have recrystallized the DNPH in acetonitrile/water I still get 5 peaks in my blank. one before the ACN peak and 3 after. My mobile phase is 60% ACN in 0.5% H3PO4. UV at 365nm.All peaks come out before the glutaraldehyde-DNPH peak. Column is Restek TO-11 at 35 C.
-------------------------------------------------------------------------------------------------------
By Consumer Products Guy on Thursday, August 19, 2004 - 07:41 am:
We assay glutaraldehyde in finished products using DNPH as well. We use deactivated C18 column at 365nm with ACN and H3PO4 as well (we use higher concentration of H3PO4). We obtain only the excess DNPH peak and the glutaraldehyde peak. Unfortunately, I'm not sure how to attach our chromatogram, it's in Word format.
-------------------------------------------------------------------------------------------------------
By Jaime on Thursday, August 19, 2004 - 10:56 am:
What brand is your DNPH powdered chemical?Who sells them?
-------------------------------------------------------------------------------------------------------
By Consumer Products Guy on Thursday, August 19, 2004 - 11:01 am:
Aldrich D19,930-1
-------------------------------------------------------------------------------------------------------
By Consumer Products Guy on Thursday, August 19, 2004 - 11:02 am:
Also Mallinckrodt #2412 (my sample is over 20 years old though)
-------------------------------------------------------------------------------------------------------
By HW Mueller on Thursday, August 19, 2004 - 11:48 pm:
Are you talking about dinitrophenylhydrazine?
If so, CP Guy, what reaction conditions are you using? The old H2SO4 method we used years ago produced a multitude of products which mostly emerged with the solvent front, luckily. (We had another problem, though, and gave up: Ascorbic acid produces two osazone geometric isomers which interconvert at a slightly slower rate than the chrom time span. Nevertheless a problem, which, however, should not occur here).
Oh yes, we had a peak appearing, sometimes, at various retention times, never got it under control. Have any of you seen this type of thing in this reaction?
-------------------------------------------------------------------------------------------------------
By Consumer Products Guy on Friday, August 20, 2004 - 07:52 am:
Yes, 2,4-dinitrophenylhydrazine; we've only used it for low levels of formaldehyde and glutaraldehyde, because those were the only aldehyde analytes of interest to my company. We haven't had any issues.
James R. Dahlgren and Melvin N. Jameson, “Determination of Formaldehyde and Other Aldehydes in Industrial Surfactants by Liquid Chromatographic Separation of Their Respective 2,4-Dinitrophenyl-hydrazone Derivatives,â€