evaluation of several field test kits for determining concentrations of arsenic in drinking water j....
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Evaluation of Several Field Test Evaluation of Several Field Test Kits for Determining Kits for Determining
Concentrations of Arsenic in Concentrations of Arsenic in Drinking WaterDrinking WaterJ. Mitchell Spear,
You “Mark” ZhouCharles A. Cole
andYuefeng F. Xie
Environmental ProgramsPenn State Harrisburg
Penn State HarrisburgPenn State Harrisburg
US EPA Small Public Water Systems Technology US EPA Small Public Water Systems Technology Assistance CenterAssistance Center
http://www.hbg.psu.edu/etc/
• RegulationRegulation– Published arsenic rule (January 22, 2001)Published arsenic rule (January 22, 2001)– Lowers Maximum Contaminant Level from Lowers Maximum Contaminant Level from
50 ug/L to 10 ug/L Arsenic50 ug/L to 10 ug/L Arsenic– Compliance date (January 23, 2006)Compliance date (January 23, 2006)
• Water Utilities affectedWater Utilities affected– Approximately 4000 in USApproximately 4000 in US– 97 % serving less than 10,000 people97 % serving less than 10,000 people
• Removal OptionsRemoval Options– Best Available Technologies (BAT)Best Available Technologies (BAT)– Small System Compliance Technologies Small System Compliance Technologies
(SSCT)(SSCT)
BackgroundBackground
• Point-Of-Use (POU) OptionsPoint-Of-Use (POU) Options
– Activated AluminaActivated Alumina– Ion ExchangeIon Exchange– Iron Based Sorption MediaIron Based Sorption Media– Reverse OsmosisReverse Osmosis
• MonitoringMonitoring
– Graphite Furnace Atomic Absorption (GFAA)Graphite Furnace Atomic Absorption (GFAA)– Inductively Coupled Plasma Emissions Inductively Coupled Plasma Emissions
Spectrophotometry (ICP-AES)Spectrophotometry (ICP-AES)– Inductively Coupled Plasma Mass Inductively Coupled Plasma Mass
Spectroscopy (ICP-MS)Spectroscopy (ICP-MS)– Hydride Generation Atomic Adsorption Hydride Generation Atomic Adsorption
(HGAA)(HGAA)
BackgroundBackground
• Evaluate several Evaluate several commercially available field commercially available field test kits and determine test kits and determine reliability and applicability reliability and applicability to water utilities currently to water utilities currently conducting noncompliance conducting noncompliance arsenic analyses.arsenic analyses.
PurposePurpose
• Test KitsTest Kits– selectionselection– chemistrychemistry– reference methodreference method
• Laboratory performanceLaboratory performance– accuracy accuracy – precisionprecision
• Matrix interference and field Matrix interference and field performanceperformance– Antimony and sulfideAntimony and sulfide– Linearity on field sampleLinearity on field sample
• Operator performanceOperator performance– operator biasoperator bias– ““ease of use”ease of use”
MethodsMethods
Test Test KitsKits
General CharacteristicsGeneral Characteristics
Test Kit Concentration Intervals Number of Reagents
Test Time (min)
BVC-100 10, 25, 50, 100, 500 2 13
ECO-W100 25, 50, 100, 150, 200, 300, 500, 750 4 35
Hach 10, 30, 50, 70, 300, 500 5 40
LaMotte 4, 6, 8, 10, 12, 14, 16, 18, 20, 30, 40, 50, 60, 70, 80, 100, 140, 160
3 16
Merck 10, 25, 50, 100, 500 2 32
Quick II 1, 2, 2.5, 3, 4, 5, 6, 7, 10, 12, 14, 20, 30, >30, >40, >60, >80, >100
3 16
Trace Detect Continuous 3 10
General CharacteristicsGeneral Characteristics
Test KitSample size
(ml)Unit Price
($ US dollars) Samples per kit $ Cost / test
BVC-100 10 30.00 100 0.30
ECO-W100 10 36.00 100 0.36
Hach 50 106.00 100 1.06
LaMotte250 153.00 50 3.06
Merck 10 69.60 100 0.70
Quick II100 219.99 50 4.40
Trace Detect 50 12,500.00 5000 2.50
MethodsMethodsSelection of Field Test KitsSelection of Field Test Kits
InexpensiveInexpensive Commercially availableCommercially available PortablePortable Multiple lot numbersMultiple lot numbers Seven field kitsSeven field kits
MethodsMethodsChemistry of Field Test KitsChemistry of Field Test Kits
Arsine gas generation Arsine gas generation (similar to SM 3114) Hydride (similar to SM 3114) Hydride
generationgenerationSemi-qualitativeSemi-qualitative
Anodic Stripping Voltammetry Anodic Stripping Voltammetry (ASV)(ASV)
(similar to SM 3130)(similar to SM 3130)QualitativeQualitative
MethodsMethodsChemistry of Field Test KitsChemistry of Field Test Kits
0
2
4
6
10
Zinc
HCL,H2SO4,Tartaric,Sulfamic
Ferrous, NickelSalts
PotassiumPeroxymonosulfate Oxidize
Stronglyreduce
Catalyst
Sample
ArsenicIII
ArsenicV
Mercury (II)Bromide
AsH2HgBr
AsH3(g)
ColorChart
TestStrip
MethodsMethods
Reference MethodReference Method
US EPA approvedUS EPA approved
EPA Method 7060A EPA Method 7060A (Graphite Furnace Atomic (Graphite Furnace Atomic Absorbance)Absorbance)
Laboratory PerformanceLaboratory Performance
Accuracy and PrecisionAccuracy and Precision
Traditionally (Method Detection Traditionally (Method Detection Limit)Limit)
Accuracy (percent recovery)Accuracy (percent recovery)% Recovery = Conc% Recovery = ConcTestKit TestKit / Conc/ ConcGFAAGFAA * 100 * 100
Precision (standard deviation)Precision (standard deviation) Arsenic III, V, III + VArsenic III, V, III + V ConcentrationConcentration ReplicatesReplicates
Laboratory PerformanceLaboratory Performance
ResultsResults
0
20
40
60
80
100
120
BVCECO
Hach
LaM
otte
Mer
ck
Quic
k II
(old
)
Quic
k II
(new)
Trace
Dete
ct
Per
cen
t R
eco
very
As III
As V
As III + V
Matrix interference and Matrix interference and Field PerformanceField Performance
Antimony levelsAntimony levels(0, 0.25, 1.0 and 5.0 mg/L)(0, 0.25, 1.0 and 5.0 mg/L)
Sulfide levelsSulfide levels(0, 0.5, 5.0 and 10.0 mg/L)(0, 0.5, 5.0 and 10.0 mg/L)
LinearityLinearity (5, 10, 25, 50, 75 µg/L)(5, 10, 25, 50, 75 µg/L)
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
BVCECO
Hach
LaM
otte
Mer
ck
Quic
k II
(new)
Trace
Dete
ct
Per
cen
t R
eco
very
0 mg/L Sb
0.25 mg/L Sb
1 mg/L Sb
5 mg/L Sb
0.0
20.0
40.0
60.0
80.0
100.0
120.0
BVCECO
Hach
LaM
otte
Mer
ck
Quic
k II
(new)
Trace
Dete
ct
Per
cen
t R
eco
very
0 mg/L Sulfide
0.5 mg/L Sulfide
5 mg/L Sulfide
10 mg/L Sulfide
y = 0.66x - 4.1
y = 0.28x - 2.4
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80 90
GFAA (ug/L)
Mea
sure
d a
rsen
ic in
tes
t ki
ts (
ug
/L)
BVC
ECO
Linear (NoBias)Linear (ECO)
Linear (BVC)
y = 0.85x + 3.2
y = 0.73x - 6.5
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80 90
GFAA (ug/L)
Mea
sure
d a
rsen
ic in
tes
t ki
ts (
ug
/L)
Hach
LaMotte
Linear (No Bias)
Linear (LaMotte)
Linear (Hach)
y = 0.77x + 1.4
y = 0.56x - 4.1
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80 90
GFAA (ug/L)
Mea
sure
d a
rsen
ic in
tes
t ki
ts
(ug
/L)
Merck
Quick II
Linear (No Bias)
Linear (Quick II)
Linear (Merck)
y = 0.
90x -
1.5
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80 90
GFAA (ug/L)
Mea
sure
d v
alu
e in
tes
t ki
t (u
g/L
)
TraceDetect
Linear (No Bias)
Linear (TraceDetect)
Operator PerformanceOperator Performance
Operator BiasOperator BiasSchock and George (1993)Schock and George (1993)
“ “Ease of Use”Ease of Use”InstructionsInstructionsChemical additionsChemical additionsEquipmentEquipmentResult interpretationResult interpretationScale Scale • 1 - most difficult1 - most difficult• 10 - easiest 10 - easiest
Operator bias
Test kit Operator 1 Slope
(intercept)Correlation coefficient
BVC-100 Operator 40.87(0.0)
0.897*
ECO-W100 Operator 40.99
(-1.6)0.905*
Hach Operator 20.84
(2.44)0.829*
LaMotte Operator 31.0
(0.77)0.890*
Merck Operator 30.47(4.9)
0.689*
Quick II Operator 20.90(1.0)
0.873*
* Significant to the 0.01 alpha level.
a
c
aaa
bb
0
2
4
6
8
10
Operator “Ease of Use”
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
