The_Analytical_Scientist_-_February_2019 (1)

https://www.cdsanalytical.com/pyrolyzer

Certain phthalate additives are known
to be harmful to humans, resulting in
regulations regarding their use. With
growing environmental awareness and
perceptions, the use of phthalates has been
restricted in many countries, including the
European Union and the United States of
America. As a result, a few international
standards and conformity assessment
bodies such as the International
Electrotechnical Commission (IEC)
and the American Society for Testing
and Materials (ASTM), have published
standards for determining certain
phthalates in polymeric materials. The
recent IEC Method 62321-8 defines
approaches to determine di-isobutyl
phthalate (DIBP), di-n-butyl phthalate
(DBP), benzyl butyl phthalate (BBP),
bis-2-ethyl hexyl phthalate (DEHP), di-
n-octyl phthalate (DNOP), di-isononyl
phthalate (DINP) and di-iso-decyl
phthalate (DIDP) in electronics using
GC-MS and TD-GC-MS.
Thermal extraction of additives is a
straightforward approach involving only
a few steps and therefore the possibility of
greater recovery when compared to solvent
extraction techniques. Sample is simply
placed in a sample tube and dropped into

the Drop-In-Sample-Chamber (DISC)

of a 6150 Pyroprobe. The Pyroprobe

thermally extracts the sample using two

sequential temperature ramps as defined

in the Experimental Parameters, straight

to a single quad GC-MS. Resulting

chromatograms closely match the

chromatograms in Annex C.2 of the

IEC Method (Figure 1). Calibration

curves based on a one-point calibration (as

indicated in the method) are also shown

in Figure 1.

The statistical measures related to

reproducibility depend on temperature

precision, along with sample related issues

like homogeneity and sample preparation.

Eight replicates a 500ng phthalate

standard provided area RSDs of around

3% for most of the phthalates, which

gives a very small statistical variation.

Furthermore, when method detection

limits were studied in accordance with the

IEC method, seven replicates produced

calculated MDLs ranging from 9.4 to

21.7 mg/kg, 78-91 percent lower than the

100mg/kg requirement (Table 1).

The latest version of the Pyroprobe from

CDS Analytical ensures repeatable, reliable

results for thermal extraction of phthalates

in accordance with standard methods, like

IEC Method 6321-8 for determination of

phthalates in electrotechnical products.

Experimental Parameters

The samples were thermally extracted

in a CDS Pyroprobe 6150 with an

Autosampler, equipped with Drop-In-

Sample-Chamber (DISC) technology. A

DISC tube was used as the sample vessel.

Pyro Chamber:

Ramp 1: 2 00°C to 300°C at 20°C/minute

Ramp 2: 3 00°C to 340°C at 5°C/minute

IsoZones: 300°C

GC-MS:

Column: 5 % phenyl (30m x 0.25mm)

Carrier: Helium, 50:1 split

Injector: 32 0°C

Oven: 8 0°C for 13 minutes

2 0°C/min to 300°C

Mass

Range: 5 0-1000amu

Thermal

Extraction of

Phthalates in

Polymers based

on IEC Method

62321-8 using a

Pyroprobe

Phthalate calibration,
reproducibility and MDL studies
using an IEC standard method

By Karen Sam

Figure 1: Calibration curve and chromatograms (TIC and EIC) of phthalates.

Phthalate Quant Ion RSD (%) (mg/kg)MDL

DIBP 223 3.2 21.7

DBP 223 2.3 21.0

BBP 206 4.3 21.0

DEHP 279 2.9 14.7

DNOP 279 3.2 9.4

DINP 293 3.0 17.9

DIDP 307 3.2 13.6

Table 1: Area RSDs and calculated MDLs

of phthalates

(^44)  (^) Application Note