I would like to know what is the most accurate and fast method for measuring the methanol content of formaldehyde solution (formalin)? Usually, it can be determined indirectly, based on the formalin content and its relation with methanol content.
Is it any equipment available which can directly determine the content of methanol directly (without the long procedure for the prior preparation of the sample like dilution or mixing with some other solvents,...) for industrial application? HPLC or GC can be the standard and good choice for this purpose?
Thanks
Methanol can be determined by Gas chromatography with FID detector but formaldehyde do not have a high response factor using FID and you can detect only high concentrations so less than 5ppm very difficult to quantify. You can perform formaldehyde derivatization by 2,4-DNP (2,4-Dinitrophenyl hydrazine) and you will have good peak on HPLC -UV.
So if you need to analyze the formalin which is 40% furaldehyde solution you can just use GC-FID without problem to see both components. Do not forget about dilution before injection.
Good luck!
Dear Karen,
Thanks for your answer, so, GC-FID can be used to detect both formaldehyde and methanol. I have formalin ~37-42%. SO I can prepare a diluted sample using 2,4 DNPH, then inject it to GC, and I can get the peaks for both formaldehyde and methanol, am I right?
Hello, no for GC -FID you not need dervatization with 2.4DNPH.
For GC just dilute your sample and inject.