Third VOC study--Effect of cold and hot detergent washes and rinses

Table 7. Summary of findings from the third VOC study--

Effect of cold and hot detergent washes and rinses.

Mean desorbed concentration (mg/L) after the following treatments

Cold wash

Hot wash

10-min sorb /10-min desorb

Material

MNT TCE

PDCB PCE

MNT TCE PDCB PCE

PVC

LD

PTFE

LD <0.005 <0.008

0.010

LD

SS

Not done

24-hr sorb/10-min desorb

PVC

LD

PTFE

LD

0.010

0.023

LD

SS

LD

Not done

24-hr sorb/24-hr desorb

PVC

0.004 0.023

0.026

0.019

LD

PTFE

0.013 0.159

0.165

0.334

LD

0.046 0.034

0.068

SS

LD

Not done

MDL

0.003 0.004

0.005

0.009

LD = less than detection limit.

detergent washing (i.e., those exposed to a 24-

tion from the PVC pieces that were exposed to the

hour sorption/desorption regime).

test solution for 10 minutes. As expected, rinsing

was least effective in removing the contamination

Fourth VOC study--Effect of solvent rinsing

from the PTFE test pieces.

Table 8 clearly shows that neither the methanol

nor hexane solvent rinses improved removal of

Third VOC study--Effect of cold and hot

any of these analytes from the PTFE test pieces. It

detergent washes and rinses

is not surprising that a solvent rinse was not ef-

Table 7 shows the effectiveness of detergent

fective in removing contamination from this

washing and rinsing at room temperature (called

a cold wash) and at ~100C (called a hot wash).

polymer because presumably the bulk of the re-

sidual contamination comes from within the

The room temperature detergent wash and rinse

polymer matrix.

was effective for removing contamination from

the stainless steel surfaces. This was also true for

Fifth VOC study--Effect of room temperature and

the PVC test pieces as long as the desorption time

oven air drying

was 10 minutes.

The hot water detergent wash and rinse fol-

The hot water detergent wash and rinse was

effective in removing contamination from all the

PVC test pieces, irrespective of the sorption/des-

Table 8. Summary of findings from the fourth

orption scheme, and from all the PTFE test pieces

VOC study--Effect of solvent rinsing on PTFE.

except those exposed to a 24-hour/24-hour sorp-

tion/desorption regime.

Mean desorbed conc. (mg/L) after

The findings from this study and the previous

decontamination treatment

Treatment

MNT TCE PDCB PCE

study agree with what Parker (1995) predicted:

the nonpermeable stainless steel surfaces are

Hot detergent wash and

LD

0.040

0.052

0.063

much more readily decontaminated than the

hot water rinse

more sorptive polymeric materials; the most

Hot detergent wash, hot

LD

0.041

0.051

0.059

sorptive polymeric material, PTFE, is the most

water rinse, and methanol

difficult to decontaminate; and the longer the

rinse

contact time, the more difficult it is to decontami-

Hot detergent wash, hot

LD

0.045

0.055

0.070

nate.

water rinse, and hexane

rinse

The next three studies focus on trying to re-

MDL

0.002

0.006

0.007

0.006

move residual contamination from PTFE pieces

that were not effectively decontaminated by

LD = less than detection limit.

10