A comparative study and evaluation of methodologies used for ...

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A comparative study and evaluation of methodologies used for ...

A comparative study and

evaluation of methodologies used

for determining wood

preservative penetration

Radu Craciun, Ralf Moeller, Joachim Wittenzellner, Thomas Jakob,

and Joerg Habicht

Dr. Wolman GmbH / BASF Group,

Sinzheim, Germany

IRG 42-nd Annual Meeting

Queenstown, New Zeeland

May 08-12, 2011

18.03.2009 INTERN 1


18.03.2009

Key steps for evaluating new wood

preservative systems

Treatment

Process

Environment/

exposure

conditions

Chemical

stability

Efficacy - wood protection

Biostability/

bio

degradation

Fixation/

Leaching

INTERN

Penetration

UV stability/

weathering

2


18.03.2009

Overview – why penetration studies ?

� Review various method to determine the wood

preservative/product penetration into the core part of the

wood:

- Indirect color indicator/tracers,

- Direct treating solution uptake

- Gradient analysis: solvent

extraction/chromatography analysis

- Laboratory microbiology methods/what really works!

� Correlation studies between various methods used in

penetration studies (color vs. gradient vs. microbiology)

� Concluding remarks/what the industry needs !?

INTERN

3


18.03.2009

Indirect penetration color indicator

- copper/quat/other additives/traces profiles -

(A) for -a Br-phenol quat-based for system, quats (a) and Cr-azurol (B) for foracopper copper (b); based and other system,

indicators for Cu-modified systems (c - other type of matrix)

(a)

(b)

INTERN

4


Direct gradient analysis

- Solvent extraction/chromatography at various depths -

18.03.2009

(a) Scots pine wood blocks used in this penetration study.

(b) Cross sections of the wood blocks showing the marked

analytical zones (A, C) and the sealed cross section (B).

(a) (b)

- Wood grinding corresponding to each zone followed by solvent

extraction or acid digestion

- AAS/ICP for metal analysis (Cu, B, As) or HPLC/GC for organic

biocides (e.g. tri-azoles) in metal-organic systems

INTERN

5


Test set up: wafers taken for ende sealed pine boards samples (20 x 4

x 4 cm³) DV or VPT impregnated. Wafer cut out from the centre of the

treated wood (as shown in the picture below).


18.03.2009

Direct microbiology penetration method

- methodology setup/test design -

40 mm

40 mm

Samples for EN 113

Petri dish

fungal mycelium

growth medium

200 mm

EN113 EN113

fungi fungi

analytics

wood

section

sample holder

INTERN

Cross sections sealed

Samples for screening II

6


Microbiology penetration method

- results from various types of fungi used in the test -

18.03.2009

(a) P.p. exposed treated wafers with Cu-based and organic systems

(b) Exposed untreated control wafer

(c) Exposed and dreid untreated control wafer

(a)

(b)

(c)

INTERN

7


18.03.2009

Indirect penetration color indicator

- copper profile in modified systems -

(A) for a- quat-based Cr-azurol forsystem, copper; and penetration (B) for aprofiles copperfor based Cu-amine system,

modified systems – matrix effect

(a) – no penetration enhancement additive

(b) – with penetration enhancement additive

(a) (b)

INTERN

8


Direct microbiology penetration method

- copper depth profile with 2 different fungi (Cp/Gt) -

18.03.2009

- Cu penetration profiles for Cu-amine systems – matrix effect,

(where Coniophora puteana, Cp – top/Gloeophyllum trabeum, Gt – bottom)

(a) – no penetration enhancement additive

(b) – with penetration enhancement additive

(A) for a quat-based system, and (B) for a copper based system,

(a) (b)

INTERN

9


Correlation between the direct analytical

gradient and microbiology profile methods

- for VPT using organic-based systems -

(A)

(a)

(A) for a quat-based system, and (B) for a copper based system,

18.03.2009

(b)

Organic a.i. retention [mg/g wood]

600

400

200

Gradient of organic a.i. in the vacuum-treated wood blocks

- penetration data for Organic - I versus Organic - I + Penetration Enhancement Additive -

0

0 2 4 6 8 10 12 14

Penetration depth [mm]

Organic - I

Organic - I + Additive C1

Organic - I + Additive C2

(B)

INTERN

10


Double vacuum/envelop penetration studies

- microbiology penetration profile method -

18.03.2009

(A) (B)

(A) - experimental exposure

conditions - initial

(B) - various application procedures -

after exposure

(C) - Effect of DV pressure profile -

after exposure

- Blue stain used:

Aureobasidium pullulans

and Sydowia polyspora

INTERN

11


18.03.2009

Conclusions

� The key parameter to be monitored = distribution of active

ingredients in the treated wood/penetration gradient

� Penetration gradient depends directly of matrix/product composition,

wood species, type of treatment, pressure profile, concentration

� Even if laborious, the direct solvent extraction/chromatography the

most reliable (when interferences from wood components solved)

� Microbiology method – proven to be a direct, quick and useful R&D

tool for evaluating product penetration in new formulation development

� Industry needs: simple, easy to use, reliable, preferable directed

toward the active component; for indirect methods data should be

generated to proof or correlate penetration of product/actives with the

direct methods

INTERN

12


18.03.2009

Questions ????

INTERN

13

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