Natural Science Forum / Chemistry / Analytical Chemistry / July 2007

We are in the process of analysing low concentrations (10 -20 ppb) of
silver in water samples using APHA spectrophotometric dithizone method
(3500 Ag). The exact problem we encounter was in dithizone extraction
from the white precipitate with CCl4. No colour was developed with

can anyone suggest a  hplc method for stigmasterol and sytosterols.we
are equiped with uv detector and normal and reverse phase column.

Im a MSc. student from Mumbai. I want to use Gas Chromatograph for
estimating phenol in urine samples. I want to know the exact method
for estimating phenol in urine sample by gas chromatography. Shall I
directly use urine samples or there is need to standardize those

Anyone have any insight into this phenomenon?
Titanium custom machined quadrupole ion trap that slowly over time lost the
ability to "see" polar compounds (e.g. ethyl acetate, alcohols).
Cleaning the MS with sandblasting, jewellers rouge, and solvents has not

I've been observing a phenomenon using an LC-ESI-MS/MS method with
RP18 column (2x55 mm, 3µm) to quantify a small molecule (Mr ~ 350,
cyclic amino acid with a rather lipophilc substitution at the hetero-
N) which I have trouble explaining properly:

Hi all, coming from an electronics/engineering background so I
apologize if there's an easy answer to this, I haven't come across it
yet...
I'm interested in being able to sense/measure alcohol fermentations