evaluation of several field test kits for determining concentrations of arsenic in drinking water j....

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

Contact Information

http://www.hbg.psu.edu/etc/