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Re: 522 1,4-Dioxane Sensitivity
Posted: Tue Jul 16, 2024 2:25 pm
by jtingson
What type of column are you using for analysis? Are you following method oven parameters? What activated carbon cartridges are you using? We are currently using Waters Sep-pak and have also tried the Phenomenex cartridges as well, but it has not given much difference as far as the coelution of the M+ 58 ion. We also employ a promochrome automated SPE system and have not experimented with a manual SPE manifold just yet. Is your SPE done manually?
Re: 522 1,4-Dioxane Sensitivity
Posted: Tue Jul 16, 2024 4:40 pm
by jtingson
We haven't had any luck resolving the M+ 58 peak either, although we can get down to 0.1 ug/L for 1,4-dioxane before the ion ratio integration falls outside of the method spec.
(Previously, this had been consistently <0.04 ug/L in our lab for the 100 mL extraction option before something in the supplies changed). All of our solvent blanks and unextracted blanks are still clean. A large bolus of the unknown contaminant comes off when first wetting the carbon cartridge, then it seems clean until the methanol is in the extraction and then more comes elutes off.
What type of column are you using for analysis? Are you following method oven parameters? What activated carbon cartridges are you using? We are currently using Waters Sep-pak and have also tried the Phenomenex cartridges as well, but it has not given much difference as far as the coelution of the M+ 58 ion. We also employ a promochrome automated SPE system and have not experimented with a manual SPE manifold just yet. Is your SPE done manually?
Re: 522 1,4-Dioxane Sensitivity
Posted: Wed Jul 17, 2024 1:28 pm
by bcd_GCLCMSMS
Waters Sep Pak AC-2
Restek Rxi-624 Sil MS 0.25 mm (using the oven profile in the method)
Helium at 1 mL/min (through Agilent big universal trap)
Dichloromethane - Honeywell (B&J)
Methanol - Honeywell (B&J) P&T
1 uL injection size
We reviewed multiple vendors for our solvents and these are the best we found through actual testing looking for the interfering peak.
Re: 522 1,4-Dioxane Sensitivity
Posted: Wed Jul 24, 2024 3:04 pm
by jtingson
I have recently tried and found success on getting the confirmatory ion down using a RTX-VMS 30x0.25mmIDx1.4um column
Re: 522 1,4-Dioxane Sensitivity
Posted: Wed Jul 24, 2024 5:28 pm
by bcd_GCLCMSMS
I have recently tried and found success on getting the confirmatory ion down using a RTX-VMS 30x0.25mmIDx1.4um column
By success, you mean that you can separate the M+ 58 impurity on the Rtx-VMS column? That would be great news.