Metrohm 797 VA Computrace Uživatelský manuál stáhnout pdf (Strana 282)

9 Troubleshooting

797 VA Computrace – Software

270

deposition even with concentrations ρ > 100 μg/L (e.g. DP voltam-

metry at the HMDE or also at the DME).

The effects of a deposition time which is too long are shown by the

following two examples:

• Nickel and cobalt determination in the trace region

by cathodic adsorption stripping voltammetry (with

dimethylglyoxime complexes)

Prolongation of the deposition time from 30 s to 120 s (kee-

ping all other measurement parameters constant) leads to non-

linear standard additions and in the case of nickel also to shifts

in the peak maximum:

Deposition time: 30 s Deposition time: 120 s

Analysis solution: 20 μg/L Ni; 20 μg/L Co

Supporting electrolyte: 0.1 mol/L NH

Cl/NH

; pH = 9.3

5⋅10

-4

mol/L dimethylglyoxime (DMG)

Standard addition: with 200 ng Ni / 200 ng Co

Electrode: HMDE

• Mercury determination at the gold electrode

On prolongation of the enrichment time from 30 s to 240 s,

side peaks appear during standard addition:

Enrichment time: 30 s Enrichment time: 240 s

1 2 ... 277 278 279 280 281 282 283 284 285 286 287 ... 294 295

Žádné komentáře

Metrohm 797 VA Computrace Uživatelský manuál Strana 282