Ask The Expert Webinar Series

Comparative Review of Analytical Methods for

Determination of 1,4-Dioxane: Which One Is

Best For My Project?

Eric Redman

Director of Technical Services

TestAmerica

Michael Wilken

Technology Team

The Dow Chemical Company

As a solvent stabilizer for

1,1,1-Trichloroethane

(TCA) and other

chlorinated solvents

As a solvent in lacquers,

paints, resins, pharma,

etc.

As a contaminant in

ethoxylation chemistry

and products (surfactants,

detergents, PEG)

Potential Sources/Uses

EPA Superfund Survey 2003

Synthetic industrial

chemical

Completely miscible in

water – Very low Henry’s

law constant

Low vapor pressure for

VOCs

Boiling point near water

Density near water

Migrates rapidly in

groundwater – weak

adsorption to particulates

Physical and Chemical

Properties

High water solubility +

low VOC vapor pressure

= poor “inert gas”

extraction efficiency

Poor purge efficiency

Elevated reporting

limits

Calibration anomalies

Carryover problems

Analytical Challenges –

Method 8260 – Full Scan

Very common method

supported at 17 TestAmerica

labs

RLs range from 40 – 1000 ug/L.

Median at 100 ug/L

MDLs range from 10 – 150 ug/L.

Median ~ 40 ug/L

LCS recovery of 40 – 160% is

typical. Average near 100% at

many labs but significant variability

High frequency of positives > MDL

in MBs (3%)

Method 8260B Full Scan –

QC Criteria

8260 Full Scan Chromatographs

Reporting Limit Standard

Lab A

100 ppb

Lab B

100 ppb

3 8260 MBs after 10,000 ppb

Calibration Standard Injection

MB #1

1300 ppb

MB #3

< 10 ppb

MB #2

65 ppb

High water solubility +

high SVOC vapor

pressure = poor

“liquid/liquid” extraction

efficiency

LLE methods 3510 and

3520

LCS recoveries are

lower than average for

SVOCs

Inherent low bias

Analytical Challenges –

Method 8270 Full Scan

Relatively common method

supported at 9 TestAmerica Labs

RLs range from 1 – 20 ug/L.

Median at 10 ug/L

MDLs range from 0.5 – 10 ug/L.

Median ~ 3 ug/L

LCS recovery of 30 – 70% is

typical. Average near 50% at

many labs, but less variability

than 8260

Low frequency of positives > MDL

in MBs (< 0.5%)

Method 8270 Full Scan

QC Criteria

8270 Full Scan Chromatographs

Reporting Limit Standard

Lab A 10 ppb Lab B 10 ppb

8260- both samples

and standards are

extracted

8270- only samples

are extracted

8260 vs 8270 Full Scan –

Sample Results

Pros

Widely available

Low cost in conjunction with

other analytes

Can accommodate high

concentration samples

Cons

Low bias for 8270

High RLs for 8260

Carryover potential for 8260

8260 and 8270 Full Scan –

Pros and Cons

UCMR 3 – Method Reference Limit = 0.07 ppb

Presence in Drinking Water

4915 PWS tested using Method 522 with 1,4-

Dioxane detected in 1077 systems (21%)

Prevalence/Occurrence in DW

EPA calculated 10E-6 cancer risk at 0.35 ug/L and

established non-enforceable screening level for residential

water use at 0.67 ug/L. Still no MCL.

Snapshot of Regulatory Levels

Enforceable State Limits

MA Regulatory Limit = 0.30 ug/L

NJ Regulatory Limit = 0.40 ug/L

CO Cleanup Standard = 0.35

ug/L

NH Reporting Limit = 0.25 ug/L

CA Notification Level = 1.00 ug/L

C.Hiegel with TriHydro, as presented at NEMC in August,

2016

Provides low RLs (at or below

0.2 ug/L)

Uses “solid phase” extraction

(SPE) without extract

concentration

Optimized for 1,4-Dioxane

Uses Selected Ion Monitoring

Improved accuracy and

precision

LCS limits 70-130%

Average recovery 93%

Uses low sample volume

Applicable to surface water and

groundwater as well as DW

Strengths of Method 522

Method 522 – Best Available

Good sensitivity at the RL (0.2

ug/L)

Rugged, reliable, accurate, and

precise.

BUT………..

Not widely available

Standalone method for 1,4-

Dioxane

Higher cost

No isotope dilution/recovery

correction if matrix impacts

Not routinely applied to

wastewater or industrial discharge

Use Selected Ion Monitoring

(SIM)

Results in improved sensitivity

Apply isotope dilution

technique

Corrects for poor extraction

efficiency

Reduces calibration anomalies

Improves ruggedness and

reproducibility

Optimize ‘inert gas’ extraction

for 8260

Can We Improve Methods 8260

and 8270?

8270 Concentration Loss-

Fixed with Isotope Dilution

8270 SIM With Isotope Dilution

Good sensitivity at RL (0.4 ug/L)

RLs equivalent to 522 if needed

LCS recovery 90 – 110%

Average recovery 101%

Can be coupled with other SIM

analytes (PAHs, PCP, etc)

Uses ‘standard’ 8270 liquid/liquid

extractions and sample volumes

Applicable to wastewater,

industrial discharge, and other

complex matrices, IF low RLs

required

1 ppb Standard by 8260 SIM-

Heated Purge + Isotope Dilution

Lab A Lab B

100X improvement!

8260 SIM With Isotope Dilution

and Heated Purge

Sufficient sensitivity at 1 ug/L

RLs < 1 ug/L difficult to achieve

Reliable detection at 0.4 ug/L only

with significant laboratory effort

LCS recovery 80 – 120%

Average recovery 105%

Can be coupled with other VOC

SIM analytes (VC, EDB, TCP, etc)

Widely available

Relatively low cost

Vulnerable to carryover

Lab B at 0.4 ug/L

Annual Dow PT Samples

Annual PT samples 11 preferred laboratories

Plus 10 other laboratories

Blended real samples For VOC, SVOC, metals,

anions analysis

1,4-Dioxane from all

available methods in lab

No 1,4-dioxane spiked

0

200

400

600

800

1000

1200

1400

1 2 3 4 5 6 7 8 9 10 11 21 1 2 3 4 5 6 7 8 9 10 11

µg

/l

Comparison 8260 and 8270 PT Study NEAT sample

8260

8260 SIM

8260 Isotope

HRGC/HRMS

8270

8270 SIM

8270 Isotope

8270

*

‡

0

100

200

300

400

1 2 3 4 5 6 7 8 9 10 11 21 1 2 3 4 5 6 7 8 9 10 11

µg

/l

Comparison 8260 and 8270 PT Study DILUTED samples 8260

8260

8260 SIM

8260 SIM

8260 Isotope

8260 Isotope

HRGC/HRMS

HRGC/HRMS

8270

8270

8270 SIM

8270 SIM

8270 Isotope

8270 Isotope

8260 8270

* ‡

8260

* corrected for recovery rate

‡ continuous extraction

Annual Dow PT samples

Direct Comparison With Different Samples

• 4 preferred

laboratories

• Blended real samples

• 1,4-Dioxane from all

available methods in

lab

• No 1,4-dioxane

spiked

0

5000

10000

15000

20000

25000

30000

µg

/l

Sample 1 (neat)

0

1000

2000

3000

4000

5000

6000

µg

/l

Sample 2 (diluted) ‡ continuous extraction

Direct Comparison - Different Samples

Direct Comparison Over Wider Concentration Range

3 preferred

laboratories

Blended real samples

Diluted 1:10 and 1:100

No 1,4-dioxane spiked

1900

2290 2310

2070 2020

2360

1460

735

1170

209 231

250 180 186

232 129 98.4

78.6 0 18.8 0

19.1 18.5

21.8 15.9

9.7 5.79

0

500

1000

1500

2000

2500

82

60

C

82

60

C

82

60

C

82

60

C SIM

82

60

C SIM

82

60

B SIM

82

70

D

82

70

D

82

70

D

82

60

C

82

60

C

82

60

C

82

60

C SIM

82

60

C SIM

82

60

B SIM

82

70

D

82

70

D

82

70

D

82

60

C

82

60

C

82

60

C

82

60

C SIM

82

60

C SIM

82

60

B SIM

82

70

D

82

70

D

82

70

Dµ

g/l

1,4-Dioxane comparison 8260 vs 8270

neat sample

1:10 dilution 1:100 dilution

Direct Comparison Over Wider Concentration Range

0

20

40

60

80

100

120

140

% R

eco

very

rate

Recovery Rate 8260

0

20

40

60

80

100

120

140

% R

eco

very

rat

e

Recovery Rate 8270

Recovery Rate Comparison

Summary

VOC methods (8260) deliver

substantially higher data than

unmodified 8270 in all studies

with REAL WORLD samples

The differences can be up to a

factor of 3

This may be due to:

poor extraction and no surrogate

recovery correction

VOC methods are not capable

of analyzing in sub ppb-range

without further optimization

Method 522 does not require

surrogate recovery correction

Moving Forward

We are in urgent need of a reliable

method!

One step is the implementation of the

isotope dilution method

Why? The differences between VOC

and SVOC methods may be the result

of NOT correcting for recovery rate of

surrogate standard(s) which are

typically only 30% - 70% for SVOC

(8270) methods

Isotope dilution corrects for low

recoveries and extraction variability

8270-SIM with isotope dilution

provides data quality equivalent to

Method 522, and better than 8260-

SIM for RLs < 1 ppb

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Comparative Review of Analytical Methods for Determination of

1,4-Dioxane: Which One Is Best For My Project?