J. Gailer et Kj. Irgolic, THE ION-CHROMATOGRAPHIC BEHAVIOR OF ARSENITE, ARSENATE, METHYLARSONICACID AND DIMETHYLARSINIC ACID ON THE HAMILTON PRP-X100 ANION-EXCHANGECOLUMN, Applied organometallic chemistry, 8(2), 1994, pp. 129-140
The HPLC separation of arsenite, arsenate, methylarsonic acid and dime
thylarsinic acid has been studied in the past but not in a systematic
manner. The dependence of the retention times of these arsenic compoun
ds on the PH of the mobile phase, on the concentration and the chemica
l composition of buffer solutions (phosphate, acetate, potassium hydro
gen phthalate) and on the presence of sodium sulfate or nickel sulfate
in the mobile phase was investigated using a Hamilton PRP-X100 anion-
exchange column. With a flame atomic absorption detector and arsenic c
oncentrations of at least 10 mg dm-3 all investigated mobile phases wi
ll separate the four arsenic compounds at appropriate pH values in the
range 4-8. The shortest analysis time (approximately 3 min) was achie
ved with a 0.006 mol dm-3 potassium hydrogen phthalate mobile phase at
pH 4, the longest (approximately 10 min) with 0.006 mol dm-3 sodium s
ulfate at pH 5.9 at a flow rate of 1.5 cm3 min-1. With a graphite furn
ace atomic absorption detector at the required, much lower, flow rate
of approximately 0.2 cm3 min-1 acceptable separations were achievable
only with the pH 6 phosphate buffer (0.03 mol dm-3) and the nickel sul
fate solution (0.005 mol dm-3) as the mobile phase. To become detectab
le approximately 100 ng arsenic from each arsenic compound (100 mul in
jection) must be chromatographed with the phosphate buffer, and approx
imately 10 ng with the nickel sulfate solution.