Chromatography Forum

Has been working on the method EPA 1694:Pharmaceutical Compounds in Water.

Specifically, acetaminophen.

The specified internal standard for use is 13C3-Atrazine.

We could not purchase this internal standard as my region is not accessible enough so we were thinking of using a substitute which is 13C3, 15N3- Atrazine.

I searched up and saw that sigma quoted 13C3, 15N3- Atrazine as having a mass shift of +6. I could not find the mass shift quoted on 13C3-Atrazine when I googled it.

Can anyone please help by explaining to me if this substitute of internal standard works and since there is 3 15N isotopes, what should my parent-daughter m/z be given that that for 13C3-Atrazine as stated in the method is 219.5-176.9

I had been thinking about this alone and had googled but to no avail. So, I hope that anyone who have experience or knowledge regarding this could help me.

Thank you for the kind effort.

hts123 wrote:
Has been working on the method EPA 1694:Pharmaceutical Compounds in Water.

Specifically, acetaminophen.

The specified internal standard for use is 13C3-Atrazine.

We could not purchase this internal standard as my region is not accessible enough so we were thinking of using a substitute which is 13C3, 15N3- Atrazine.

I searched up and saw that sigma quoted 13C3, 15N3- Atrazine as having a mass shift of +6. I could not find the mass shift quoted on 13C3-Atrazine when I googled it.

Can anyone please help by explaining to me if this substitute of internal standard works and since there is 3 15N isotopes, what should my parent-daughter m/z be given that that for 13C3-Atrazine as stated in the method is 219.5-176.9

I had been thinking about this alone and had googled but to no avail. So, I hope that anyone who have experience or knowledge regarding this could help me.

Thank you for the kind effort.

Since carbon is normally 12 and nitrogen is normally 14, having 3 C13 and 3 N15 molecules would increase the total by 6 amu, while having 3 C13 on the 13C3-Atrazine would only increase the total by 3 amu. I would begin by optimizing using the internal standard alone and look for 222.5 as the parent.

Either of those analytes should work as the internal standard for Acetaminophen.

Acetaminophen works well by this method.

Thank you for the reply . I will try it .