Alcohol Method Development by GC-MS

[ChantalM]

Have you developed a method?

I have the same problem and like to hear how I can solve this.

[chemist23]

Our hand sanitizer products were over 60% ethanol, but in our validation studies boss made us go down to extremely low levels, even those would be so many orders of magnitude less than our target levels. He was "afraid" of ever having to answer a question should an auditor ask.

I am having difficulty extracting all of the alcohol from hand sanitizer products in the form of a 'gel'. While it appears the gel fully dissolved in water, the results of my alcohol content say otherwise. Did you always use water as your solvent and have you ever tested a gel matrix? If so what solvent did you use?

[Consumer Products Guy]

I am having difficulty extracting all of the alcohol from hand sanitizer products in the form of a 'gel'. While it appears the gel fully dissolved in water, the results of my alcohol content say otherwise. Did you always use water as your solvent and have you ever tested a gel matrix? If so what solvent did you use?

Our alcohol-containing products were hand sanitizer gels; we always used water as the solvent, and had no issues with our assay. We also cGMP-validated the USP procedure, adapted for our gel finished product, our pointy-haired boss demanded that.

Production QC also had no issues with the procedure.

There were some potentially proprietary sample preparation innovations we developed to aid in the analysis of a volatile analyte accurately. One involved weighing 3 gram sample into a volumetric flask already containing about 50 ml water.

[chemist23]

I am having difficulty extracting all of the alcohol from hand sanitizer products in the form of a 'gel'. While it appears the gel fully dissolved in water, the results of my alcohol content say otherwise. Did you always use water as your solvent and have you ever tested a gel matrix? If so what solvent did you use?

Our alcohol-containing products were hand sanitizer gels; we always used water as the solvent, and had no issues with our assay. We also cGMP-validated the USP procedure, adapted for our gel finished product, our pointy-haired boss demanded that.

Production QC also had no issues with the procedure.

There were some potentially proprietary sample preparation innovations we developed to aid in the analysis of a volatile analyte accurately. One involved weighing 3 gram sample into a volumetric flask already containing about 50 ml water.

Measuring by weight would be easier than trying to pipette a specific volume. But then how would you get your result in v/v%? the only way I assume would be to know the density of the gel.

[chemist23]

I am having difficulty extracting all of the alcohol from hand sanitizer products in the form of a 'gel'. While it appears the gel fully dissolved in water, the results of my alcohol content say otherwise. Did you always use water as your solvent and have you ever tested a gel matrix? If so what solvent did you use?

Our alcohol-containing products were hand sanitizer gels; we always used water as the solvent, and had no issues with our assay. We also cGMP-validated the USP procedure, adapted for our gel finished product, our pointy-haired boss demanded that.

Production QC also had no issues with the procedure.

There were some potentially proprietary sample preparation innovations we developed to aid in the analysis of a volatile analyte accurately. One involved weighing 3 gram sample into a volumetric flask already containing about 50 ml water.

Measuring by weight would be easier than trying to pipette a specific volume. But then how would you get your result in v/v%? the only way I assume would be to know the density of the gel.

Confirming that measuring by weight seemed to have worked and using online tables to convert w/w to v/v% can be found. Thanks!

[Consumer Products Guy]

Measuring by weight would be easier than trying to pipette a specific volume. But then how would you get your result in v/v%? the only way I assume would be to know the density of the gel.

Yes, we knew the density of the alcohol gel product. Our product also had tiny air bubbles entrapped in it, marketing gimmick. Due to the gel nature of the product, would've been difficult to sample by volume; taking a relatively large sample size of 3 grams provided made any potential randomness of the air bubbles negligible, and was relatively fast way to sample.

Purell brand also contains such bubbles

[chemist23]

please describe the results

Followed USP 611 and incorporated weight rather than volume in the calculation. The results obtained matched what was indicated on the label of different brands hand sanitizer gels.

[Maja Djekic]

Hello everyone,

this topic is interesting to me because I want to confirm that "alcohol-free" cosmetic cream is really free from alcohol. I planed to analyze it on GC-FID but I am not sure how to prepare the sample so I can extract alcohol (if there is any) because the cream matrix is oily? Any experiences or ideas?

Thank you in advance.

[Consumer Products Guy]

Hello everyone,

this topic is interesting to me because I want to confirm that "alcohol-free" cosmetic cream is really free from alcohol. I planed to analyze it on GC-FID but I am not sure how to prepare the sample so I can extract alcohol (if there is any) because the cream matrix is oily? Any experiences or ideas?

Thank you in advance.

First thing you need to do is define for yourself what "alcohol free" means to you or to your company. For example, would one molecule of alcohol mean that the product is not truly "alcohol free" ?

For example, very few non-alcoholic beers contain no alcohol at all. In the United States, to be labeled “alcohol-free,” beer may contain up to 0.5% alcohol by volume.

[LALman]

I'll just add that using a DB-VRX column to do alcohols is possible but I would worry about the hand cream composition. You don't want semivolatiles in the handcream getting on a column that has a max temp of 260C.

[James_Ball]

I'll just add that using a DB-VRX column to do alcohols is possible but I would worry about the hand cream composition. You don't want semivolatiles in the handcream getting on a column that has a max temp of 260C.

For something like that I would think the Rxi-624-SilMS column would be better. It has good separation for low molecular weight analytes and a max temp of about 320C.

[Maja Djekic]

Thank you for answers and suggestions

[MSCHemist]

I thought methanol was impossible to do via GC/MS you need an FID. The molecular weight of methanol is 32amu which is also the molecular weight of O2.

I do ethanol via headspace GC/ms. I use acetonitrile as the internal standard and use full evaporative. I put 10ul into a 10ml vial and heat to 120degC for 10 minutes. If I am doing an oil soluble sample I use acetone instead of water. I use a 0.5df wax coln though I am told 1701 or 624 works better.

[James_Ball]

I thought methanol was impossible to do via GC/MS you need an FID. The molecular weight of methanol is 32amu which is also the molecular weight of O2.

I do ethanol via headspace GC/ms. I use acetonitrile as the internal standard and use full evaporative. I put 10ul into a 10ml vial and heat to 120degC for 10 minutes. If I am doing an oil soluble sample I use acetone instead of water. I use a 0.5df wax coln though I am told 1701 or 624 works better.

Molecular weight is 32amu, but major ion from EI is 31amu. It is still difficult to go very low if there is any oxygen present, but not impossible to do. FID though I think will give better detection limits since it is more sensitive to methanol than MS and no interference from oxygen.

[Gizmo]

I had some luck years ago using headspace SPME, ion 31 for methanol. Used it for confirming no dangerous levels in some home made beverages.