Ultrasonic Extraction/Anodic Stripping Voltammetry for Determining Lead in Household Paint: A Laboratory Evaluation.
Ultrasonic Extraction/Anodic Stripping Voltammetry for
Determining Lead in Household Paint: A Laboratory
Evaluation.
(5353 K)
Rossiter, W. J., Jr.; Vangel, M. G.; McKnight, M. E.;
Signor, A.; Byrd, W. E.
NISTIR 6571; 64 p. April 2001.
Sponsor:
Department of Housing and Urban Development, Washington,
DC
Available from:
National Technical Information Service
(NTIS), Technology Administration, U.S. Department of
Commerce, Springfield, VA 22161.
Telephone:
1-800-553-6847 or 703-605-6000;
Fax: 703-605-6900; Rush
Service (Telephone Orders Only) 800-553-6847;
Website:
http://www.ntis.gov
Order number: PB2001-105379
Keywords:
paints; lead; anodic stripping voltammetry (ASV);
lead-based paint; lead recovery; overlayer effect
testing; ultrasonic extraction (UE)
Abstract:
A laboratory study was conducted to evaluate the
reliability of commercial, field-portable ultrasonic
extraction-anodic stripping voltammetry (UE/ASV) for
determining the lead levels of laboratory-prepared paint
films when tests were performed by certified lead
inspectors trained to conduct UE/ASV testing. Two
factory-calibrated UE/ASV apparatuses from the same
supplier were purchased and used to conduct an
experiment investigating the effects of lead level,
apparatus, lead pigment type, operator, paint-film
substrate, and overlayer applied to the lead-based paint
film. Test panels, with either white lead (i.e., basic
lead carbonate) or lead chromate pigments, had 10 lead
levels ranging from 0 mg/cm2 to 3.5 mg/cm2. The
lead-based paint films were adhered to steel or plaster
substrates, which were considered for experimental
design purposes to be difficult or easy to sample,
respectively. The overlayers were either a thickly
applied oil-based paint (about 0.75 mm to 1.4 mm) or a
thinly applied latex paint (about 0.13 mm to 0.28 mm).
The five operators were trained by a UE/ASV supplier's
representative to conduct the tests using a written
protocol developed from the supplier's instructions. The
study showed that one of the two ASV electrochemical
instruments was in calibration, whereas the response of
the second ASV instrument was low at the lower lead
concentrations used to check calibration. Consequently,
the data were analyzed both as "unadjusted for
calibration" and "adjusted for calibration." Lead levels
determined by the UE/ASV tests were often considerably
less than the lead levels in the test panels. Depending
on the combination of five experimental
factors-apparatus, operator, lead pigment type,
substrate type, and overlayer-the recovered lead for the
data adjusted for calibration ranged from 28% to 94%,
with the median recovery being 63%. These findings are
in sharp contrast with previously published results of
an UE/ASV field study in which lead recoveries generally
ranged from 75% to more than 100%. In the present study,
ASV measurement error did not appear to play a role in
the low lead recoveries based on quality assurance
measures. A key contributor appeared to be incomplete
lead solubilization during paint specimen sonication.
The major experimental factor affecting UE/ASV response
was overlayer, with test panels having thick-oil
overlayers yielding lower lead recoveries than those
with thin-latex overlayers. It may have been that
thick-oil overlayers were more difficult to sonicate,
and/or grind before sonication, than thin-latex
overlayers. Effects of the other experimental factors on
UE/ASV response were considered primarily for the
calibration-adjusted data. Operator and substrate
factors were found to have a significant effect; whereas
no effects were found for lead pigment type or
apparatus.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899