Automatic on-line pre-concentration system using a knotted reactor for the FAAS determination of lead in drinking water.
An automatic on-line pre-concentration system is proposed for lead determination in drinking water using flame atomic absorption spectrometry (FAAS). Lead(II) ions are retained as the 1-(2-pyridylazo)-2-naphthol (PAN) complex in the walls of a knotted reactor, followed by an elution step using 0.50molL(-1) hydrochloric acid solution. Optimisation involving the sampling flow rate, pH and buffer concentration factors was performed using a Box-Behnken design. Other factors were established considering results of previous experiments. The procedure allows the determination of lead with a 0.43microgL(-1) detection limit (3sigma/S) and precisions (expressed as relative standard deviation) of 4.84% (N=7) and 2.9% (N=7) for lead concentrations of 5 and 25microgL(-1), respectively. The accuracy was confirmed by the determination of lead in the NIST SRM 1643d trace elements in natural water standard reference material. The pre-concentration factor obtained is 26.5 and the sampling frequency is 48h(-1). The recovery achieved for lead determination in the presence of several ions demonstrated that this procedure could be applied to the analysis of drinking water samples. The method was applied for lead determination in drinking water samples collected in Jequié City, Brazil. The lead concentration found in 25 samples were always lower than the permissible maximum levels stipulated by World Health Organization.
Souza
Anderson S
AS
Universidade Federal da Bahia, Instituto de Química, Núcleo de Excelência em Química Analítica da Bahia, Campus Universitário de Ondina, Salvador, Bahia 40170-290, Brazil.
Brandão
Geovani C
GC
dos Santos
Walter N L
WN
Lemos
Valfredo A
VA
Ganzarolli
Edgard M
EM
Bruns
Roy E
RE
Ferreira
Sérgio L C
SL
D001938:Brazil; D002138:Calibration; D002947:Cities; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D007854:Lead / Q000032:analysis*; D009284:Naphthols; D009862:Online Systems; D015203:Reproducibility of Results; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis
D009284:Naphthols; D014874:Water Pollutants, Chemical; C041728:1-(2-pyridylazo)-2-naphthol; D007854:Lead