The LC mobile phase gradient employed 10 mM ammonium acetate
(A) and acetonitrile (B).
Combination of acetonitrile and ammonium acetate
buffer (pH 7.6) was used to set the base line.
al.' batch procedure  by the addition of 50 mg portions of the dry resin to 10 ml solution contains 100mg/l of each metal prepared in ammonium acetate
solution (1.0 M, pH 6).
Based on the obtained results, acetonitrile at concentration of 20% and water at pH 3-4 with addition of 10-20 mM ammonium acetate
or ammonium formate were considered as optimal for isoquinoline alkaloid separation on an XB-C18 core-shell column.
The ammonium acetate
concentration higher than 0.1 M was not suitable for water-soluble food dyes because of the "salting-out" effect .
Although the MS signal of analytes was higher using an eluent with a lower pH (ammonium acetate
, formic acid with pH 2.8), the separation of the compound was not followed.
Because the analytes were weak alkali, the smearing could be alleviated with the poor chromatographic peak shape after using 5 mM ammonium acetate
The chemicals used, namely benzil, aldehydes, and ammonium acetate
, were of analytical reagent grade.
Perhaps the most important disadvantage of this reagent is supplied by the resorption of metals in the residual fraction, which requires an additional extraction with ammonium acetate
at pH = 2 (SUTHERLAND et al., 2000; FERREIRA & SANTANA, 2012).
Sodium contents were determined both in 1:2 water extract and ammonium acetate
extract and are given in Table 2.
The column was equilibrated and eluted with 200 mM ammonium acetate
buffer (pH 5.2) at a flow rate of 0.3 mL/min.
Step Solvent Rhamnolipid extraction 1 Subboiling purified water (20 mL) 2 1M ammonium chloride (8 mL) 3 1M ammonium acetate
(20 mL) at pH 4 4 Mixture of 10.9 g/mL oxalic acid and 16.2 g/L ammonium oxalate (20 mL) 5 Six M hydrochloric acid (30 mL) 6 (a) 8.8 M hydrogen peroxide (5 mL, pH 2) (b) 8.8 M hydrogen peroxide (5 mL, pH2) (c) 1 M ammonium acetate
(25 mL, pH 4) 7 (a) hydrofluoric acid/aqua regia (5 mL) (b) perchloric acid (5 mL) Step Duration/temperature Seventy-two hr at room temp 1 1 hr at 95[degrees]C.