The HCl will be hard on your freeze dryer unless you have an effective trap. There's been lots of discussion of various alternate acids on this list. I've used 100% phosphoric, which has the benefit of low vapor pressure, but makes subsequent dehydration challenging. Stephanie >Folks, > >We're trying to separate siderite from soil/clay samples so that we may >analyze the organic components of the soil for d13C, d15N and CN ratios. >The refs I've come across focus on 'carbonate' removal and indicate that >siderite is less soluble. I found I can dissolve siderite in 6 molar HCl at >50°C overnite, or soaking in 6 molar HCl at 25°C for several days. To >remove excess HCl I plan to freeze dry the samples and not pour out any of >the acid in case some of the organics have also gone into solution (I think >this is the same idea as vapour removal). > >Any comments or suggestions regarding possible effects others have observed >using this method, or better methods before I follow the tedious path of >sample preparation testing? The first line of testing I was going to do was >to dose IAEA-C5 (wood) with siderite and see if THIS pretreatment affected >its d13C values. > >Thanks in advance for saving me time, > >Toti. > > >Toti Larson Ph.D. >Los Alamos National Laboratory >Earth and Environmental Sciences 505.667.9894 (lab) >Los Alamos, New Mexico 87545 550.667.8006 (office) -- *** Ecosystem Sciences Division Department of Environmental Science, Policy & Management Office: 45 Hilgard Hall Mail to: 137 Mulford Hall #3114 University of California Berkeley, CA 94720-3114 tel. 510-643-6910 fax 510-643-5098