Permethrin and GC test

[pippo]

Merck Index says it is an ester, but IUPAC says it's a carboxylate. Which is more accurate?

 

Bigger question is, let's say a GC lab tests for Permtethrin- it calibrates the GC with a standard, then tests the sample for permethrin. Permethrin does not last long in the atmosphere/nature- I understand it oxidizes/"degrades". Will the degraded form show up in the GC test as "active" permethrin? Anybody know?

 

Thanks

Edited October 18, 2015 by pippo

[John Cuthber]

Both descriptions are correct.

I doubt the GC would misidentify a degradation product as permethrin. It's the sort of thing they should have checked when they set up the method.

Incidentally, the GC will need to measure both forms (cis and trans) and add them together

[pippo]

Both descriptions are correct.

I doubt the GC would misidentify a degradation product as permethrin. It's the sort of thing they should have checked when they set up the method.

Incidentally, the GC will need to measure both forms (cis and trans) and add them together

As always, thanks, John. Good point on cis/trans.

 

My only curiosity is in pesticide residue concerns if a pesticide is "oxidized" by atmospheric oxygen (air) or even light of the right intensity (guess sunlight would be the most "powerful") and therefore the effect of that pesticide to be rendered useless/inactive, why would the GC test come up showing results as positive for say, permethrin?

 

(this is all leading to organic farming products having been exposed to permethrin, and after, being tested for permethrin residue. If the permethrin had become ineffective/useless/inactive, why would the ag product be stigmatized as having permethrin residue if it isnt even there as an effective "toxin"?)

Edited October 18, 2015 by pippo

[John Cuthber]

I'm guessing.

If I say that I run an organic farm, but I use synthetic pesticides like permethrin then I'm a liar even if the the pesticide has degraded by the time someone analyses it.

 

Also, light and air will destroy it, but they might not get to all of it. Some might be absorbed into the plant where it is protected.

[pippo]

has nothing to do with lying. Some pesticides believe it or not are allowed in some organic farming circles- dont want to get it deep with that now, but the pesticides they allow arent even tested for. So, as far as the "organic" marketing hype which is at a fever pitch right now they dictate what is "organic". It's all a hypocrisy.

 

But I appreciate your imput, John. Much to think about.

 

Also, light and air will destroy it, but they might not get to all of it. Some might be absorbed into the plant where it is protected.

good point.

Edited October 18, 2015 by pippo

[John Cuthber]

I know, but if they test for permethrin, I presume it's not permitted.

Pyrethrin probably is permitted (so's nicotine which is more toxic to people than to most insects.)

[pippo]

Right- it is not permitted for this particular crop item. BUT, thats why I was trying to get a handle on test results. I mean, heck- if it's gone (broken down/oxidized to an ineffective pesticide, etc) they shouldnt care, and it will pass as permethrin free. Dont mean to beat the subject to death, just trying to understand exactly what a GC will detect if it IS broken down. Maybe I shoyuld actually speak with the GC guy at the lab- I could find out which lab is contracted to do this test..........

 

Thnaks for your imput, John.

[hypervalent_iodine]

I doubt that all of the permethrin will have degraded. Reading up on it briefly, the cis isomer remains relatively stable in soils over the course of a few months. Further, I wouldn't imagine that the hydrolysis products would appear at the same retention time as the peak for in-tact permethrin. It should be fairly easy to discern the two.

 

I'm a little confused by your statement on it being permethrin free. If you're testing the end product of the crop and you are finding permethrin or even the break down products of permethrin, then clearly it was used as a pesticide and should not be considered "organic" for the purposes of labelling. Whether or not it's broken down by the time you get to it is rather besides the point.

[John Cuthber]

Right- it is not permitted for this particular crop item. BUT, thats why I was trying to get a handle on test results. I mean, heck- if it's gone (broken down/oxidized to an ineffective pesticide, etc) they shouldnt care, and it will pass as permethrin free. Dont mean to beat the subject to death, just trying to understand exactly what a GC will detect if it IS broken down. Maybe I shoyuld actually speak with the GC guy at the lab- I could find out which lab is contracted to do this test..........

 

Thnaks for your imput, John.

Since it showed up in the GC test, it is not "gone broken down/oxidized to an ineffective pesticide, etc ".

The point of organic food is not that the pesticides are gone by the time you eat them; it's that they were never used in the first place and thus they did not harm the environment.

Even if that viewpoint is invalid (and it's certainly debatable), saying something was grown organically when actually they used a banned pesticide is dishonest. Selling it as "organic" is fraud.

 

If it was present then, a bit of googling tells me that one of the major degradation products is

cis, trans -3- (2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid

 

If you ask the analyst they can probably look for that for you, but what's the point?

If there's permethrin there...

[pippo]

Thanks, people, for the imput. But if it's "gone", it's not there, so it's not dishonest, not that the subject of morals/"honesty" are even an issue- we're talking about a chemical being there or not. Apparently, based on the dialogue here, consensus appears to be permethrin doesnt "disappear". Therefore, I will NOT use it.

 

 

Since it showed up in the GC test, it is not "gone broken down/oxidized to an ineffective pesticide, etc ".

 

That was hypothetical- I should have explained better. I hanvnt even started yet. Maybe we are not on the same page, John, but so far, nothing happened. Just trying to understand.

Edited October 22, 2015 by pippo

[StringJunky]

"Organics" is about method of production and not just the end result

[John Cuthber]

Thanks, people, for the imput. But if it's "gone", it's not there, so it's not dishonest, not that the subject of morals/"honesty" are even an issue- we're talking about a chemical being there or not. Apparently, based on the dialogue here, consensus appears to be permethrin doesnt "disappear". Therefore, I will NOT use it.

 

 

The consensus here is not about whether the stuff goes away.

The consensus is that it is fraudulent to use non-organic pesticides and then claim that the produce is organic.

 

Not least because the wildlife that you killed with those pesticides don't come back by magic just because the poison is not there.

Do you really not understand that?

[pippo]

Update: Look, forget about the nonsense about my product being "organic", as in "organic" food. If I did not explain clearly, my fault. It is NOT food. Also, to get to the chase without the back/forth about lectured on "morals", and "fraud", etc, no one is defauding anyone. You guys have no idea what Im growing, so suffice it to say it is irrelevant.

 

I used permethrins on a partial crop, and GC tested out NEGATIVE. So, all the hype/predictions were for nothing, not to mention wrong. Just wantedf to post results of my testing/experiment on permethrins. The chemist at this lab said it this way-"they basically evaporate within 2-3 days. Looks like he was right. Product came out non detectable on GC.

Edited December 18, 2015 by pippo

[John Cuthber]

The consensus here is not about whether the stuff goes away.

The consensus is that it is fraudulent to use non-organic pesticides and then claim that the produce is organic.

 

Not least because the wildlife that you killed with those pesticides don't come back by magic just because the poison is not there.

Do you really not understand that?

It looks like you didn't understand.

Edited December 19, 2015 by John Cuthber

[pippo]

It looks like you didn't understand.

Right- because, lately, is seems you are the only one who understands everything. Your smugness is too obvious, and evident that perhaps you need to get a life(?), Im not sure- just suspect.

 

I killed NO wildlife, which you stated I did by your post. Just pesty spider mites. I have no more to say about this thread, and certainly will not continue to tit for tat with a member with such evidently low self esteem that he needs to berate/belittle fellow members on multiple threads (including my other one on mercury. )

 

Now, I have organic product to sell.........

[John Cuthber]

Well, for a start, I'm not the only one pointing out your mistakes, so most of your attack makes no sense.

 

You clearly don't need to have me here to argue since you can tit for tat with yourself.

 

You say I'm smug, but also that I have no self esteem.

Well, which is is?

 

And you also said "I killed NO wildlife" and "Just pesty spider mites."

Well, did you or didn't you?

 

 

And if you sell stuff as organic which you treated with non- organic pesticides then you are committing fraud.

[hypervalent_iodine]

Right- because, lately, is seems you are the only one who understands everything. Your smugness is too obvious, and evident that perhaps you need to get a life(?), Im not sure- just suspect.

 

I killed NO wildlife, which you stated I did by your post. Just pesty spider mites. I have no more to say about this thread, and certainly will not continue to tit for tat with a member with such evidently low self esteem that he needs to berate/belittle fellow members on multiple threads (including my other one on mercury. )

 

Now, I have organic product to sell.........

Pippo,

 

You treated your crops with a non-organic pesticide. That means that regardless of how much of it is left at the end, your product is not organic. It doesn't matter that a GC confirms there is nothing left. All that matters is that you used it at all. I do not understand why you are being so obtuse about this very simple fact.