Hello everyone,
I am a researcher working on a project aiming to develop an assay for Haemoglobin quantification.
In our assay, prior to HGB quantification we dilute the sample in a dilution buffer.
The dilution buffer we to use contains: Chloromethylisothiazolinone / Methylisothiazolinone (aka CMIT / MIT....aka Proclin 150 from Sigma).
When the buffer is stored at temperatures above 30C - 40C prior to sampling, there is a significant increase in HGB quantification compared to the control sample (using buffer stored at RT). It is obvious from our data that this change is directly related to the storage temperature of the buffer.
I have read that CMIT / MIT is metabolised to N-methylmalonamic acid upon heated conditions.
Does anyone have any understanding as to the possible impact of temperature on CMIT / MIT or its metabolite (N-methylmalonamic acid) on HGB quantification?
Isothiazolinones are used as preservatives. I'd rather not use them as they are strong contact sensitisers.
The combination is used in rinse off cosmetics - the most common preservative globally in shampoos, body washed, detergent hand soaps. At use levels (5 ppm active) the MIT is trivial - efficacy is based on the CMIT. Cosmetic stability testing includes "rapid aging" at 40C for months to simulate long term aging. In formula, CMIT is stable. However, CMIT is unstable in dilute aqueous solution (without stabilizing divalent cations) esp. at elevated temperatures/pH +/>7 and in presence of some amines. MIT is very stable. Assume Sigma has this under control in their product.
Understand N-methylmalonamic acid is a metabolite of CMIT - not the primary product of heat/pH based breakdown (file:///C:/Users/phila/Downloads/molecules-25-00991.pdf).
Why are you "storing" buffer > 40C? Sigma should have recommended against that practice.
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