Transcript Evaluation of Several Field Test Kits for Determining Concentrations of Arsenic in Drinking Water J.

Evaluation of Several Field Test Kits
for Determining Concentrations of
Arsenic in Drinking Water
J. Mitchell Spear,
You “Mark” Zhou
Charles A. Cole
and
Yuefeng F. Xie
Environmental Programs
Penn State Harrisburg
Penn State Harrisburg
US EPA Small Public Water Systems Technology
Assistance Center
http://www.hbg.psu.edu/etc/
Background
• Regulation
– Published arsenic rule (January 22, 2001)
– Lowers Maximum Contaminant Level from 50
ug/L to 10 ug/L Arsenic
– Compliance date (January 23, 2006)
• Water Utilities affected
– Approximately 4000 in US
– 97 % serving less than 10,000 people
• Removal Options
– Best Available Technologies (BAT)
– Small System Compliance Technologies (SSCT)
Background
• Point-Of-Use (POU) Options
–
–
–
–
Activated Alumina
Ion Exchange
Iron Based Sorption Media
Reverse Osmosis
• Monitoring
– Graphite Furnace Atomic Absorption (GFAA)
– Inductively Coupled Plasma Emissions
Spectrophotometry (ICP-AES)
– Inductively Coupled Plasma Mass Spectroscopy
(ICP-MS)
– Hydride Generation Atomic Adsorption (HGAA)
Purpose
• Evaluate several commercially
available field test kits and
determine reliability and
applicability to water utilities
currently conducting
noncompliance arsenic analyses.
Methods
• Test Kits
– selection
– chemistry
– reference method
• Laboratory performance
– accuracy
– precision
• Matrix interference and field performance
– Antimony and sulfide
– Linearity on field sample
• Operator performance
– operator bias
– “ease of use”
Test Kits
General Characteristics
Test Kit
BVC-100
Concentration Intervals
Number of
Reagents
Test Time
(min)
10, 25, 50, 100, 500
2
13
ECOW100
25, 50, 100, 150, 200, 300, 500, 750
4
35
Hach
10, 30, 50, 70, 300, 500
5
40
4, 6, 8, 10, 12, 14, 16, 18, 20, 30, 40,
50, 60, 70, 80, 100, 140, 160
3
16
10, 25, 50, 100, 500
2
32
1, 2, 2.5, 3, 4, 5, 6, 7, 10, 12, 14, 20,
30, >30, >40, >60, >80, >100
3
16
Continuous
3
10
LaMotte
Merck
Quick II
Trace
Detect
General Characteristics
Test Kit
BVC-100
ECO-W100
Hach
LaMotte
Merck
Quick II
Trace Detect
Sample size
(ml)
Unit Price
($ US dollars)
Samples per kit
$ Cost / test
10
30.00
100
0.30
10
36.00
100
0.36
50
106.00
100
1.06
250
153.00
50
3.06
10
69.60
100
0.70
100
219.99
50
4.40
50
12,500.00
5000
2.50
Methods
Selection of Field Test Kits





Inexpensive
Commercially available
Portable
Multiple lot numbers
Seven field kits
Methods
Chemistry of Field Test Kits
 Arsine gas generation
(similar to SM 3114) Hydride
generation
Semi-qualitative
 Anodic Stripping Voltammetry (ASV)
(similar to SM 3130)
Qualitative
Methods
Sample
Arsenic
III
Arsenic
V
Chemistry of Field Test Kits
Potassium
Peroxymonosulfate
Zinc
HCL,
H2SO4,
Tartaric,
Sulfamic
Ferrous, Nickel
Salts
Oxidize
Strongly
reduce
Test
Strip
Catalyst
AsH3(g)
0
Mercury (II)
Bromide
2
AsH2HgBr
4
6
10
Color
Chart
Methods
Reference Method
 US EPA approved
EPA Method 7060A
(Graphite Furnace Atomic
Absorbance)
Laboratory Performance
Accuracy and Precision
 Traditionally (Method Detection
Limit)
 Accuracy (percent recovery)




% Recovery = ConcTestKit / ConcGFAA * 100
Precision (standard deviation)
Arsenic III, V, III + V
Concentration
Replicates
Laboratory Performance
Results
ce
ui
ck
)
De
te
ct
ne
w
ol
d)
er
ck
II
(
M
II
(
ui
ck
Tr
a
Q
Q
ac
h
O
La
M
ot
te
H
EC
BV
C
Percent Recovery
120
100
80
As III
60
As V
40
As III + V
20
0
Matrix interference and Field
Performance
 Antimony levels
(0, 0.25, 1.0 and 5.0 mg/L)
 Sulfide levels
(0, 0.5, 5.0 and 10.0 mg/L)
 Linearity
 (5, 10, 25, 50, 75 µg/L)
120.0
100.0
0 mg/L Sb
80.0
0.25 mg/L Sb
60.0
1 mg/L Sb
40.0
5 mg/L Sb
20.0
De
te
ct
)
Tr
ac
e
Q
ui
ck
II
(n
ew
er
ck
M
La
M
ot
te
ac
h
H
O
EC
C
0.0
BV
Percent Recovery
140.0
100.0
0 mg/L Sulfide
80.0
0.5 mg/L Sulfide
60.0
5 mg/L Sulfide
40.0
10 mg/L Sulfide
20.0
De
te
ct
)
ce
Tr
a
ui
ck
II
(
ne
w
er
ck
M
Q
La
M
ot
te
ac
h
H
O
EC
C
0.0
BV
Percent Recovery
120.0
Measured arsenic in test kits (ug/L)
90
BVC
80
ECO
70
Linear (No
Bias)
Linear (ECO)
60
50
Linear (BVC)
40
y
30
.66
0
=
4.1
x
20
.4
2
x
8
2
y = 0.
10
0
0
10
20
30
40
50
GFAA (ug/L)
60
70
80
90
Measured arsenic in test kits (ug/L)
90
Hach
80
LaMotte
70
Linear (No Bias)
60
Linear (LaMotte)
50
Linear (Hach)
40
y
30
x
5
8
.
0
=
y
20
.2
3
+
3x
7
.
=0
.5
6
-
10
0
0
10
20
30
40
50
GFAA (ug/L)
60
70
80
90
Measured arsenic in test kits
(ug/L)
90
Merck
80
Quick II
70
Linear (No Bias)
60
Linear (Quick II)
50
Linear (Merck)
y=
40
x
7
0.7
30
20
10
y
.56
0
=
50
60
.4
1
+
4.1
x
0
0
10
20
30
40
GFAA (ug/L)
70
80
90
Measured value in test kit (ug/L)
90
80
TraceDetect
70
Linear (No Bias)
60
Linear (TraceDetect)
50
40
y
30
=
x
0
9
0.
.5
1
-
20
10
0
0
10
20
30
40
50
GFAA (ug/L)
60
70
80
90
Operator Performance
 Operator Bias
Schock and George (1993)
 “Ease of Use”
Instructions
Chemical additions
Equipment
Result interpretation
Scale
• 1 - most difficult
• 10 - easiest
Operator bias
Test kit
Operator 1
Slope
(intercept)
BVC-100
Operator 4
0.87
(0.0)
0.897*
ECO-W100
Operator 4
0.99
(-1.6)
0.905*
Hach
Operator 2
0.84
(2.44)
0.829*
LaMotte
Operator 3
1.0
(0.77)
0.890*
Merck
Operator 3
0.47
(4.9)
0.689*
Quick II
Operator 2
0.90
(1.0)
0.873*
* Significant to the 0.01 alpha level.
Correlation
coefficient
e
Tr
ac
t
a
et
ec
II
a
D
ck
8
Q
ui
ck
a
M
er
M
ot
te
ac
h
b
H
0
0
6
-W
10
-1
0
10
La
EC
O
BV
C
Operator “Ease of Use”
a
b
4
c
2
0
Conclusions
 Three test kits performed well
 Two field test kits met all criteria
(easy to use, accurate, precise,
inexpensive, no operator bias)
 These two could be used by water
operators for noncompliance
testing
Acknowledgements
 US EPA Small Public Water Systems
Technology Assistance Center Grant
 Peng Chen, Mukesh Pratap, Brian
Montalbano, and Paul Deardorff for
analytical analyses
 Trace Detect for loan of there
instrumentation
Contact Information
http://www.hbg.psu.edu/etc/