Natural Science Forum / Chemistry / Analytical Chemistry / October 2007

I am using NaBH4 to reduce cations (M3+).  Would it take 3 NaBH4 to
reduce it (each giving one hydride) or are all 4 H available for
reduction of the cations?
Best Regards,

I just finished experiments of GC-MS, and I have 3 undetermined peaks. I
 searched for oxysterols, but there are not (ecdysones??). Where can I
found a MS database; ie enter my peaks and get some clues?
cheers

Im working on HPLC-UV for analysis of 15 phenolic acids, Im now at
the begining  and trying to test method if works or no on the column.
Gradient is consist of mix of A (2% asetic acid in water), B( 0,5%
asetic acid in 50/50 acetonitril/water) from A to B is getting down,

I have an old HP 1047A refractive index detector, which cannot take an
HPIB card, so I cannot read the signal from it into Chemstation
software. While I intend to solve this problem by getting a Polymer Labs
light scattering detector at some point, that point is some distance

anybody has any experience with washing AND drying glassware for AA
analyses?
I would appreciate any tips on the matter.
thanks in advance,

Is there any better way to find out how much of 13C and 15N labelled
in my sample by mass spec.
current mass spectrum of my sample when comapred to unlabelled sample
shows that it has been labelled by both 13C and 15N.

I just finished experiments of GC-MS, and I have 3 undetermined peaks. I
searched for oxysterols, but there are not (ecdysones??). Where can I
found a MS database; ie enter my peaks and get some clues?
cheers

    I have a brand new HP chemstation version B installation and I am
getting this error message on multiple systems in which I have
installed the software on. I have ran the configurations and tested it
in every which way possible. I am at an absolute loss as to what might

in my lab i have a procedure by which excess KNO3 is added to an unknown HF
sample and then titrated with NaOH with phenolphthalein as indicator.
After this first titration, the sample is then placed in an 80oC waterbath
for 1 hour before conducting a 2nd titration with NaOH again ...

i have a mixed acid sample of HF+HCl+H2SO4 and i need to find out the
individual concentrations of the 3 acids. How can i do so?
Urgent help needed. Thanks.

Need Thermal Expansion Coefficients for Specific Stable Isotopes
Hello - I need the thermal expansion coefficient for specific stable
isotopes if possible. Particularly Zinc-64, Platinum-190, Platinum-192
and Platinum-194. Any questions asking "why" or "what for" will be