ESI LCMS/MS of IPU and its TPs: An Xterra MS C18 column (100 mm x 4.6 mm, 5 um, Waters Corporation, Milford, USA) was used with a binary mobile phase system comprising 0.01 M ammonium acetate
(A) and acetonitrile (B).
Different concentrations of SFV (10 ugmL-1 to 60 ugmL-1) was used to prepare the standard solution as acetonitrile and ammonium acetate
buffer (pH 7.6) was used as the mobile phase in a ratio of 50:50.
Herein, the impact of pH of 0.2M ammonium acetate
solution on the recovered percentage of the tested metal ions; Cu+2, Ni+2 and Mn+2 was investigated in the range 2-8.
Aryl aldehyde (0.1 ml/1 mM) and ammonium acetate
(0.154 g/2 mM) were added along with Ce(SO4)2 (0.236 g/ 1 mM) as catalyst.
The concentration of ammonium acetate
and pH also affected the alkaloid retention; at lower pH values and at higher salt amounts, retention times were shortened.
The mobile phase A consists of an aqueous ammonium acetate
solution 1% (m/v), brought to pH 7.5 by drop-wise addition of a sodium hydroxide solution 10% (m/v) (m/v: mass/volume).
The general trend of the aqueous phase in using methanol as the organic phase is as follows: 5 mM oxalic acid > 5 mM ammonium acetate
> 0.1% formic acid > 0.1% acetic acid.
The extraction mixture's aqueous solution's pH varied from acidic (1% acetic acid, pH 2.0) to basic (5 mM ammonium acetate
, pH 9.0 (using N[H.sub.4]OH)) conditions.
In order to increase sensitivity, ammonium acetate
was tested as a modifier.
To improve transfer in the chromatographic column other solvents were added, such as ammonium acetate
, the k-phosphate, among others.
Another method is the four-component one-pot condensation of a glyoxals, aldehydes, amines, and ammonium acetate
in refluxing acetic acid, which is the most desirable and convenient method .
The use of solutions buffered at pH 5.0 have long been used at this stage, for example, the buffer acetic acid / sodium acetate or acetic acid / ammonium acetate
at pH 5.0 allowing the release occurrence of organic and inorganic metal substrates (AHNSTROM & PARKER, 2001; LI et al., 2001).
Na content was also determined in ammonium acetate
The column was eluted with a gradient of ammonium acetate
buffer (pH 5.2) at a flow rate of 5.0 mL/min and the sugar content was monitored by an evaporative light scattering detector with the eluate split 1 : 25 between the detector and the fraction collector.
Mobile phases used were 75: 25 2.5 mM ammonium acetate
: acetonitrile pH 4.5 (A) and 75: 25 250 mM ammonium acetate
: acetonitrile pH 4.5 (B) with a binary gradient (t = 0 min, A 100%; t = 5 min, A 100%; t = 18 min, 65% A; t = 20 min, B100%; t = 22 min, A100%; t = 32 min, A100%).