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Measurement of copper concentration in Cu-HDO treating solutions by handheld XRF
2022 - IRG/WP 22-20685
Copper based preservatives diluted in water dominate the wood preservative industry around the world. Periodically measurements and adjustments of the concentration of treating solutions must be performed as a part of the quality control at the treatment plant to achieve desired quality of the preservative treated wood. Many analytical methods are time consuming and must be performed under laboratory conditions, while others that are rapid and easy to apply at industry sites can be sensitive to impact from impurities, etc. The aim of this study was to evaluate handheld X-ray fluorescence (XRF) spectrometry as a tool for measuring copper concentration in CuHDO treating solutions. The material used in the study comprised samples of Wolmanit CX-8 (CuHDO) diluted in distilled water and samples from Wolmanit CX-8 treating solutions from Norwegian impregnation plants. All the preservative solution samples were analysed with a handheld Niton XL5 Plus XRF Analyzer. Atomic absorption spectrophotometry (AAS) was used as a reference method. The major advantages of portable handheld XRF spectrometry include: on-site immediate availability of analytical results, non-destructive analysis, a multielement capability, speed of operation and access to valuable/unique samples that otherwise would be unavailable or had to be transported to a laboratory for chemical analysis. The results from this study show that there is a good linear correlation with the XRF data and the corresponding laboratory results and that it is possible to use data measured with a handheld energy dispersive XRF-analyser for accurate calibrations and predictions of the copper concentration of treating solutions of Wolmanit CX-8.
P O Flaete

Determination of chlorine-containing wood preservatives in art objects using Micro-XRF
2003 - IRG/WP 03-20266
The applicability of a mobile energy-dispersive micro X-ray fluorescence (μ-XRF) spectro-meter for the analysis of organochlorine-containing wood preservatives in art objects was tested. Information about the relative degree of contamination and the efficacy of detoxification measures with emulsive solvent systems can be gained using the intensity of the chlorine signals. μ-XRF technique combines the advantages of a high spatial resolution, as needed in studies of penetration profiles and transport processes of cut sections and the possibility to analyze larger areas in a relatively short time. The method allows a non-destructive determination of the degree of surface decontamination after cleaning treatments.
J Bartoll, A Unger, S Krug, K Püschner, H Bronk

Assaying Pentachlorophenol-treated Wood Using XRF
2007 - IRG/WP 07-20362
A study was conducted to evaluate the effect of oil type on the performance of test posts treated with oil-penta and exposed in DeQueen, AR for forty years in ground contact. The original assays for the poles were done by lime ignition, a practice used sparingly today in treating plants or by independent inspectors, in part due to the complicated analysis procedure and chances for error. XRF instruments for chlorine analysis have become commonplace. The question put forward by many inspectors, agencies, and treaters is ‘Will XRF accurately predict lime ignition results?’. This study encompassed seven different oil systems. Regression analysis yielded an R2 value over 97% when using XRF to predict lime ignition values. The only caveat was that a proper calibration standard was required for the XRF analysis. Users should be confident that properly derived XRF values will match lime ignition values within 5%.
H M Barnes, C R McIntyre, D W Bullock , M H Freeman, G B Lindsey

Use of X-Ray Fluorescence (XRF) Spectroscopy to Determine 4,5-Dichloro-2-n-Octyl-4-Isothiazolin-3-one (DCOIT) in Wood
2007 - IRG/WP 07-20373
Organic preservative based systems are being developed as replacements for the metal based systems. Typically the chemical actives of organic preservative systems are analyzed using HPLC or GC. However, these analytical techniques require complex sample processing and involve relatively long analysis times. In addition the equipment requires maintenance and a skilled operator. One organic preservative that is currently being developed for a range of uses in wood preservation, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), contains both sulfur and chlorine functionality, providing the potential for the use of XRF for its analysis in both treating solutions and in wood. In this study the applicability of XRF to determine the concentration of DCOIT using the chlorine and sulfur x-ray emissions was determined.
P Walcheski, J Ashmore, D M Laganella

Chemical Analysis in Production Quality Control at Wood Treatment Plants
2008 - IRG/WP 08-20396
Analysis methods for quality control analysis in wood treatment plants have evolved with the changes in treatment preservative chemistries and analytical instrument technology. The basic hydrometer specific gravity measurements used for solution strength and classic wet chemistry methods for wood have given way to instrumental techniques such as X-ray fluorescence, automatic titrator, and HPLC. Not all of methods involve complex instrumentation, simple turbidimeters and handheld refractometers can be used for rapid solution strength testing. These newer methods are discussed in the paper as well as the increased importance of inspection and auditing of the treatment plants production by the chemical suppliers and third party inspection agencies.
P Walcheski, L Jin

Further Studies on the Distribution of Copper in Treated Wood Using an XRF Microscope Technique
2011 - IRG/WP 11-40549
There are two distinct forms of copper in aqueous copper based wood preservative systems that are currently used in the United States for treatment of southern pine lumber. These are systems using either soluble copper (typically amine based) or the more recent particulate or “micronized” copper as the primary biocide. Studies reported last year showed that there were distinct differences in the gross distribution of the copper in the high density late wood and low density early wood with treatments using these two forms of copper. This study was to further investigate these two systems using an x-ray fluorescence (XRF) microscope to provide further data on the qualitative and quantitative distribution of these two forms of copper in southern pine wood and the impact of wood structure on this deposition. Commercially treated lumber treated with ACQ type D, MCQ, and MCA were selected and analyzed by XRF in cross-section in areas showing both a strong color reaction as well as an incomplete or streaky color reaction when tested with a standard spot test copper indicator. Distinctly different patterns of copper distribution were observed with the two forms of copper, with a much more uniform distribution resulting with the soluble copper system than observed with the particulate system. Both systems deposited high concentrations of copper in the resin canals and in rays, but whereas distribution tended to be very uniform across and within the early and latewood bands in the soluble system, with the particulate systems it was comparatively low in the latewood bands, high near the surface, and produced an overall streaky distribution pattern (radial orientation) throughout the treated zone. Discussion is also presented on interpretation of the XRF micrographs including how deep it is detecting copper, as well as influence of sample orientation on results.
A Zahora

Effect of soil contact on reacted copper(II) levels in micronized copper treated wood
2013 - IRG/WP 13-30616
Small 3 to 4 mm thick and approximately 80 to 100 mm long, samples were removed from wood treated with micronized copper quat (MCQ) or micronized copper azole (MCA) and buried full length in a soil bed. Samples were removed after 2, 4 and 8 weeks. The total copper was determined by x-ray fluorescence (XRF) spectroscopy and the amount of reacted micronized copper measured by electron paramagnetic resonance (EPR) spectroscopy. The results showed that the amount of total copper retention decreased slightly with time, whereas the reacted copper levels increased with increasing soil exposure time, eventually reaching a maximum of 0.24% Cu for MCQ and 0.28% Cu for MCA. This observation confirms that mobilization of micronized copper can continue in treated wood in ground contact provided that there is unreacted micronized copper carbonate present.
Wei Xue, P Kennepohl, Xingguo Jin, J N R Ruddick

Preparation of Calibration Standards for the Analysis of Pentachlorophenol in Treated Wood by X-ray Fluorescence
2016 - IRG/WP 16-20591
The primary purpose of this project was to develop a method for preparing calibration standards that can be used by the wood treating industry to calibrate X-ray fluorescence instrumentation. Calibration standards of penta/P9-oil in southern yellow pine that cover the retention range of 0.2 to 0.9 pcf (0.6 to 1.9 %) were successfully prepared. A detailed procedure for mixing penta in treating solution with ground southern pine is described. Users can choose to reference the penta concentration in the standards based on lime ignition analysis of the treating solution or lime ignition analysis of each standard. XRF measurements of penta concentrations are 5-8% higher than the values of penta in wood measured by the lime ignition or the values of penta in wood calculated on the bases of lime ignition measured penta concentration in treating solution. Standards stored at ambient temperature were stable over a period of 1 to 1.5 years during the time of this study. This study focused on preparation of standards and does not include the effects of boring collection, storage, drying, and grinding on analytical error.
L L Ingram Jr, H M Barnes, R Shmulsky, D Jeremic

Use of small volume cups in XRF analysis of treated wood retention
2017 - IRG/WP 17-20602
Efforts are underway in the United States to improve the conformance of commercially-treated wood with the applicable retention standards. As part of an effort to devise a practical method for on-site assessment of within-charge retention variation, we investigated whether small-volume x-ray florescence (XRF) sample cups could be used with treated wood. A range of cup sizes, preservative types, retention levels and other variables were considered. In general, small volume cups appear to be suitable for use with common industrial XRF machinery. This finding is being applied to a proposed modification to the American Wood Protection Association (AWPA) standard.
R Stelzer, A Taylor, P Lebow

Discrimination of five commercial wood preservatives by handheld near-infrared spectrometers and Multivariate Data Analysis
2022 - IRG/WP 22-20686
Nowadays, the recycling potential of wood waste is still limited, because of a lack of reliable lack of a reliable and fast device allowing the discrimination of preservative-treated wood that contains organic or/and inorganic contaminants. The purpose of this study was to set up a methodology, based on a SCiO low-cost handheld NIR spectrometer, and multivariate data analysis (MDA). Spectra was obtained on solid maritime pine (Pinus pinaster) wood impregnated with 5 different commercial preservatives at 3 different concentration levels (50, 70, 100%). Two classification methodologies were used: PLS-DA, and SVM-DA. Additional statistical analysis (Student's t-test with a significance level of 5%) highlight the absorption bands impacted by the presence of the wood preservative. For classification methodologies, several criteria were used to compare the performance of the classification models. Regarding the universal F1 Score performance criterion, SVM-DA model outperforms the PLS-DA model. Compared to PLS-DA model, SVM-DA model has been improved by 65%. Another criterion, such as, Sensitivity, indicated, For SVM-DA, that the correctly classified is comprised between 82 to 100%, whereas, for PLS-DA, the correctly classified is comprised between 43 to 90%. These findings show that the SCiO low-cost handheld NIR spectrometer coupled to MDA, such as SVM-DA model is useful to correctly classifying preservative-treated wood and opens new possibility in wood waste recycling.
M Rubini, P Dulucq, B Charrier