Ultrasonic extraction of hexavalent chromium in solid samples followed by automated analysis using a combination of supported liquid membrane extraction and UV detection in a flow system
K. Ndung'U et al., Ultrasonic extraction of hexavalent chromium in solid samples followed by automated analysis using a combination of supported liquid membrane extraction and UV detection in a flow system, ANALYST, 124(9), 1999, pp. 1367-1372
A simple and sensitive supported liquid membrane (SLM) extraction technique
for the determination of Cr(VI) in occupational hygiene and environmental
samples has been developed. Solid samples were ultrasonicated for 30 min at
40 degrees C in ammonium or phosphate buffers. The samples containing Cr(V
I) were extracted using the SLM technique for 20 min and Cr(VI) was determi
ned on-line in a flow system by reaction with 1,5-diphenylcarbazide (DPC).
The detection limits after a 20 min SLM enrichment at a flow rate of 1 ml m
in(-1) were 0.63 mu g l(-1) using a 5 mM phosphate buffer at pH 7.0 and 1.1
8 mu g l(-1) using a 10 mM ammonium buffer at pH 8.0. The corresponding det
ection limits for an alternative approach using electrothermal atomic absor
ption spectrometry (GFAAS) off-line after 20 min SLM enrichment were 0.04 m
u g l(-1) and 0.03 mu g l(-1) for ammonium and phosphate buffers, respectiv
ely. The method was validated using a new certified reference material for
Cr(VI) and total leachable Cr in welding dust, CRM 545, from the European C
ommission's Community Bureau of Reference (BCR). The method should be adapt
able for both field sampling and analysis.