United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas NV 89193-3478
Research and Development
EPA/600/S4-88/012 Apr. 1988
4>EPA Project Summary
A Single-Laboratory
Evaluation of SW-846 Methods
7090/7091 Determination of
Beryllium by Flame and
Furnace Atomic Absorption
Spectrophotometry
Vernon F. Hodge, Daniel A. Darby, Wendy E. Thompson, and Clifton L. Jones
The results of a single-laboratory
study of the SW-846 Method 70907
7091 — "Determination of Beryllium
by Flame and Furnace Atomic Absorp-
tion Spectrophotometry" are de-
scribed. This study examined the appli-
cation of these two powerful beryllium
detection methods to the analysis of
selected liquid and solid samples after
digestion by appropriate SW-846
methods. Method performance data,
including: detection limits, optimum
concentration ranges (linearity), spike
recoveries, interferences, precision,
accuracy, and optimum instrument
operating parameters, are presented
and discussed.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing Systems Laboratory, Las Vegas,
NV, to announce key findings of the
research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
The single-laboratory evaluation of
SW-846 Methods 7090/7091 for the
determination of beryllium by flame and
furnace atomic absorption Spectropho-
tometry (AAS) was undertaken in order
to obtain method-performance data and
to augment existing data. The method-
performance parameters studied were:
1. Detection Limits
2. Optimum Concentration Ranges
(Linearity)
3. Spike Recoveries
4. Interferences
5. Precision
6. Accuracy
7. Ruggedness Testing
All data were collected according to the
procedures described in "Guidelines for
Selection and Validation of U.S. EPAs
Measurement Methods" (Draft, January
30, 1986) and "Test Methods for Eva-
luating Solid Waste," SW-846 (Third
Edition, November 1986).
Method 7090 and Method 7091 are
measurement procedures for the deter-
mination of beryllium in solution. There-
fore, solid waste samples, and most
aqueous samples, require digestion prior
to analysis. Twelve performance evalua-
tion or target samples were chosen for
this study. Five of these were liquid
samples, two of which were U.S.
National Bureau of Standards—Standard
Reference Materials(NBS-SRMS). There
were seven solid samples of which two
were NBS-SRMS, two were Certified
Reference Materials from Canada (one
from the National Research Council,
Ottawa, and one from the Centre for
Mineral and Energy Technology, Ottawa)
-------
and one solid was a U.S. EPA-CLP
Reference Material prepared by the
UNLV-QAL. The liquid samples to be
analyzed by flame AAS (Method 7090)
were digested according to Method
3010, and the liquid samples to be
analyzed by furnace AAS (Method 7091)
were digested according to Method
3020. All solid samples were digested
by Method 3050 prior to analyses.
Instrument detection limits and the
optimum concentration ranges were
determined in aqueous samples that
were free from interferences. Method-
detection limits, spike recoveries, preci-
sion, and accuracy were determined in
digests of each of the 12 target samples.
The stability of beryllium in the sample
digests was monitored for 30 days.
A survey of the literature revealed
several reports of elements whose
presence in solutions containing beryl-
lium, caused increased or decreased
absorbance, thereby giving erroneously
high or low concentration measurements
for beryllium. Therefore, the individual
effects of Al, Mg, and Si on the deter-
mination of beryllium by flame AAS
(Method 7090) and of Al, Ca, Ce, Cr, La,
Mg, Mn, Mo, Si, Sr, H2S04, W, and Fe
by furnace AAS (Method 7091) were
investigated. Several chemicals includ-
ing hydrofluoric acid, 8-hydroxyquinoline
and lanthanum were reported to elim-
inate some of the interferences. The
usefulness of these additives was also
investigated.
Conclusions
The single-laboratory evaluation of
Method 7090 and Method 7091 demon-
strates that the methods are sensitive,
precise, and accurate for the quantifica-
tion of beryllium in a variety of solutions.
The solutions targeted by this study
included acid digests of liquid and solid
samples according to SW-846 digestion
Method 3010, Method 3020, and Method
3050. The performance parameters
determined in this study for the two
methods are summarized below.
Determination of Beryllium by
Acetylene/Nitrous Oxide
Flame Atomic Absorption
Spectrophotometry (Method
7090)
The instrument detection limit (IDL) for
the determination of beryllium by flame
AAS in a matrix free from interferences
was found to be 0.003 mg/L. The
optimum concentration range, also in a
matrix free from interferences, was
found to be 0.01 mg/L to 2.6 mg/L.
The analysis of the 12 liquid and solid
samples that were digested by Method
3010 or Method 3050 yielded a method
detection limit (based on 1 -g/100 mL for
solids) of 0.005 mg/L, or, two times the
IDL (Table 1). The percent relative
standard deviation (%RSD) was used as
a measure of the precision of the method,
and it ranged from about five percent at
0.02 mg/L to less than one percent at
0.75 mg/L. Recoveries of predigestion
spikes of beryllium at 0.25 mg/L and
0.50 mg/L averaged 89 percent (99
percent with the addition of 0.1 percent
hydrofluoric acid (Table 2).
Aluminum was found to be the only
element, of the five investigated, that
interfered with the determination of
beryllium (40 percent depression of
absorbance at 1000 mg/L and 54 per-
cent at 5000 mg/L). The addition of 0.1
percent hydrofluoric acid or 2.5 percent
8-hydroxyquinoline were found to be
effective in eliminating this interference
for concentrations of aluminum up to
1000 mg/L. The addition of 0.3 percent
hydrofluoric acid was effective in elim-
inating the interference of aluminum at
5000 mg/L. By using modern instrumen-
tation, high concentrations of Mg and Si
(up to 5000 mg/L) did not interfere with
the determination of beryllium as cur-
rently stated in Method 7090.
The accuracy of Method 7090 was
evaluated by determining the beryllium
concentration in three NBS-SRMs,
before and after digestion by SW-846
methods, with excellent results.
Determination of Beryllium by
Furnace Atomic Absorption
Spectrophotometry (Method
7091)
The instrument detection limit for
beryllium in a matrix free from interfer-
ences was found to be 0.08 /Jg/L (Table
3). The optimum concentration range,
also in a matrix free from interferences,
was found to be from 0.01 /jg/L to 16
The analysis of 12 liquid and solid
samples, which were digested by Method
3020 or Method 3050, yielded a method
detection limit of 0.08 fjg/L, the value
of which is the same as the instrument
detection limit, demonstrating that a
variety of matrices had little or no effect
on the detection of beryllium. The percent
RSD was used as a measure of the
precision and ranged from an average of
7 perce nt at conce ntrations below 3 //g/L
to an average of 2.3 percent at concen-
trations above 3 jug/L. Recoveries of
predigestion spikes of beryllium at 2.5
ug/L and 5.0 //g/L averaged 93 percent.
A literature survey suggested that the
presence of any one of 12 elements can
enhance or depress the absorbance of
beryllium in the furnace analysis. How-
ever, it was found that when peak area
was used to calculate the concentration
Table 1. Method Detection Limit for the Determination of Beryllium by Flame Atomic
Absorption Spectrophotometry, Method 7090
Matrix
Trace Elements in Water
Beryllium Spectrometric Solution
Synthetic Interference Solution
Natural Waste Water
TCLP Extract of Hazardous Waste
Coal Fly Ash
Municipal Digested Sludge
Three Kids Mine Material
Marine Sediment
Mineral Sample
Hazardous Waste Site Soil
Copper-Beryllium Alloy
Average
Slope'
0.92
0.90
0.54
0.90
0.94
0.77
0.73
0.64
0.74
0.68
0.73
0.90
0.78
MDL (ug/L)'
4.4
4.4
7.4
4.5
4.0
5.2
5.4
6.3
5.4
5.9
5.5
4.4
5.2
aThe method detection limit is defined by MDL = 3 Sa/m, where SB is the standard deviation
of the instrument background signal and m is the slope of the calibration line in the sample
matrix.
-------
T»ble 2. Predigestion Spike Recoveries of Beryllium Determined by Flame Atomic Absorption
Spectrophotometry, Method 7090, After Digestion of Liquids by Method 3010 and
Solids by Method 3050
Trace Elements in Water
Beryllium Spectrometric
Solution
Synthetic Interference Solution
Natural Waste Water
TCLP Extract of Hazardous
Waste
Coal Fly Ash
Municipal Digested Sludge
Three Kids Mine Material
Marine Sediment
Mineral Sample
Hazardous Waste Soil
Copper-Beryllium Alloy
Be Added
(mg/L)
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.250
0.500
0.500
1.000
Percent
Recovery
Without HF
112
106
104
106
78
87
67
106
101
95
97
87
86
83
78
74
85
82
78
79
85
83
98
96
Percent
Recovery
With HF'
109
103
106
105
104
104
105
106
—
—
98
96
85
82
101
97
98
97
89
87
103
101
99
96
'With the addition ofO. 1 percent HF.
Table 3.
Matrix
Method Detection Limit for the Determination of Beryllium by Furnace Atomic
Absorption Spectrophotometry. Method 7091
Slope'
MDL(ug/L)B
Trace Elements in Water
Beryllium Spectrometric Solution
Synthetic Interference Solution
Natural Waste Water
TCLP Extract of Hazardous Waste
Coal Fly Ash
Municipal Digested Sludge
Three Kids Mine Material
Marine Sediment
Mineral Sample
Hazardous Waste Site Soil
Copper-Beryllium Alloy
Average
0.99
0.95
1.01
1.06
1.08
0.99
0.93
0.96
0.94
0.97
0.94
0.85
0.97
0.08
0.08
0.08
0.08
0.07
0.08
0.09
0.08
0.08
0.08
0.09
0.09
0.08
*The method detection limit is defined by MDL = 3 SB/rn, where SB is the standard deviation
of the instrument background signal and m is the slope of the calibration line in the sample
matrix.
of beryllium in the presence of these
elements, only molybdenum interfered
with the determination of beryllium
(Table 4). The presence of 1000 mg/L
molybdenum enhanced the peak area of
a 5 /ug/L solution of beryllium by 20
percent.
The accuracy of Method 7091 was
evaluated by determining the concentra-
tion of beryllium in three NBS-SRMS
before and after digestion by SW-846
Methods, with excellent results.
Recommendations
The following recommendations are
listed by method, with section references
made to the method as written in SW-
846.
Method 7090
3.0 Interferences
3.2 This section states that "Back-
ground correction may be required. . ."
This statement should be modified to
read "Background correction is required.
3.3 This section warnsthat "Concen-
trations of aluminum greater than 500
ppm may suppress beryllium absor-
bance." This statement should be
modifed to read "Concentrations of
aluminum greater than 700 mg/L will
suppress beryllium absorbance." The
addition of 0.1 percent hydrofluoric acid
was found to be effective in eliminating
this interference as stated in the current
version of the method. However, this
study demonstrated that 0.3 percent
hydrofluoric acid is required for alumi-
num concentrations greater than 1000
mg/L.
With regard to the statement, "High
concentration of magnesium and silicon.
. ." no evidence was obtained to corrob-
orate this statement; no significant
interferences from Mg or Si at concen-
trations up to 5000 mg/L were observed
in this single-laboratory study using
modern instrumentation. Therefore, it is
recommended that this sentence be
deleted.
9.0 Method Performance
9.1 While the results of this study
yielded somewhat different values for the
optimum concentration range and detec-
tion limit, the values currently cited in
Method 7090 are near the experimental
levels found in this study. Therefore, no
changes are recommended for this
section.
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Table 4. Effect of Aluminum, Calcium, Cerium,Chromium, Lanthanum, Magnesium, Manganese, Molybdenum, Silicon, Strontium, Sulluric
Acid, Tungsten, and Iron on the Observed Absorbance of Beryllium in Furnace Atomic Absorption Spectrophotometry, Method
7091
Interfering
Element
Img/L) Al Ca Ce
Observed Be Absorbance
Cr La Mg
in Presnce
Mn
of these Chemicals"
Mo Si Sr HiS
?O4 W Fe
Peak Area
0
100
500
1000
5000
Peak Height
0.427
0.424
0.444
0.421
0.400
0.427
0.452
0.430
0.423
0.452
0.427
0.430
0.430
0.406
0.388
0.427
0.419
0.414
0.408
0.387
0.427
0.457
0.449
0.443
0.438
0.427
0.470
0.475
0.468
0.484
0.427
0.458
0.464
0.466
0.467
0.427
0.431
0.467
0.513
0.805
0.427
0.434
0.437
0.435
0.408
0.427
0.460
0.450
0.445
0.448
0.427
0.446
0.428
0.432
0.427
0.427
0.370
0.363
0.343
0.330
0.427
0.435
0.427
0.433
0.430
0
100
500
1000
5000
0.427
0.398
0.498
0.474
0.479
0.427
0.524
0.719
0.755
1.074
0.427
0.432
0.517
0.657
0.551
0.427
0.445
0.578
0.587
0.495
0.427
0.476
0.722
0.901
0.621
0.427
0.620
0.846
0.841
0.715
0.427
0.465
0.452
0.455
0.703
0.427
0.431
0.465
0.504
0.777
0.427
0.433
0.442
0.449
0.437
0.427
0.494
0.638
0.688
0.978
0.427
0.473
0.458
0.451
0.431
0.427
0.378
0.387
0.372
0.349
0.427
0.558
0.520
0.544
0.491
'Data has been normalized.
Method 7091
3.0 Interferences
3.2 The results obtained in this study
document that the method is essentially
free from interferences from 10 of the
11 elements tested. Only molybdenum
produced an interference, enhancing the
absorbance at concentrations of 1000
mg/L and above. Section 3.2 should be
modified to read "Chemical and physical
interferences can be minimized by
optimizing the furnace AAS parameters
and by using peak area instead of height
in concentration calculations."
4.0 Apparatus and Materials
4.2 Instrument Parameters (general).
It is recommended that this section be
titled: "Instrument Parameters (with
pyrolytically coated platform supported
by an uncoated graphite tube)."
The following conditions are
recommended:
4.2.1 Drying
4.2.2 Ashing
,4.2.3 Atomizing
4.2.4 Cleaning
The following rewording in the
"NOTE:" is suggested:
"NOTE: The above instrument
conditions are for a Perkin-
Elmer HGA-500 graphite fur-
Time(s) Temp. (°C)
Ramp
5
5
0
1
Hold
25
25
4
1
200
900
2700
2700
nace equipped with an AS-40
Auto Sampler. Concentration
values are based on a 10 /A.
injection with stop-flow at atom-
ization and use of a pyrolytically
coated graphite platform. Instru-
ments made by different manu-
facturers may require a differnt
set of conditions."
9.0 Method Performance
The following changes are recom-
mended to make the sections in Method
7090 and Method 7091 similar.
9.1 The performance characteristics
for an aqueous sample free of interfer-
ences are:
Optimum concentration range:
0.1 Aig/L-16//g/L
Sensitivity: 0.4/ug/L
Detection Limit: 0.08 fjg/L
9.2 In a single-laboratory analysis of
liquid and solid materials prepared by
Method 3020 or Method 3050, with
beryllium concentrations below 3 fjg/L,
the %RSD averaged 7 percent. For
samples with beryllium concentrations
above 3 percent, the %RSD was 2.3
percent. Spike recoveries average 93
percent.
This report is in partial fulfillment of
contract number 68-01-7159 by the
Environmental Research Center of the
University of Nevada, under the sponsor-
ship of the U.S. Environmental Protection
Agency. This report covers work per-
formed during the period January 1987
to August 1987.
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Vernon F. Hodge, Daniel A. Darby. Wendy E. Thompson, and Clifton L. Jones
are with the University of Nevada, Las Vegas, NV 89119-9970.
Thomas A. Hinners is the EPA Project Officer (see below).
The complete report, entitled "A Single-Laboratory Evaluation of SW-846
Methods 7090/7091 Determination of Beryllium by Flame and Furnace
Atomic Absorption Spectrophotometry," (Order No. PB 88-171 434/AS; Cost:
$19.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Las Vegas, NV 89193-3478
U.S. Government Printing Office: 1988—548-158/67116
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-88/012
0000329 f»S
•«""
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