[article]
| Titre : |
VOC testing comparison : EPA method 24 versus the cal poly method |
| Type de document : |
texte imprimé |
| Auteurs : |
V. C. Bud Jenkins, Auteur ; Joseph C. Reilly, Auteur ; Bob Sypowicz, Auteur ; Max T. Wills, Auteur |
| Année de publication : |
1995 |
| Article en page(s) : |
p. 53-59 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Chimie analytique
Composés organiques volatils
Etudes comparatives
Revêtements en phase aqueuse:Peinture en phase aqueuse
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
The Cal Poly distillation modification of the Karl Fischer water determination of ASTM D 4017 gives accurate and precise water content of coatings and consequently better VOC values on waterborne paints. The precision appears to be substantially better than that obtained with previous methods. A relative reproductibility of 2.85% at the 95% confidence level was obtained on four coatings with water contents ranging from 32 to 72%. Azeotropic distillation of water with 1-methoxy-2-propanol followed by Karl Fischer titration of the distillate appears to be applicable to many different coatings types. The distillation offers several advantages, including the elimination of numerous potential interfering materials which are known to react with Karl Fischer reagent, the prevention to electrode fouling by polymer, and allows the use of the more general and extensively documented ASTM E 203 Karl Fischer titration method for water determination.
Mathematical modeling shows that waterborne coatings with greater than 60% water content or VOC contents lower than about 160 g/L are extremely difficult to analyze using the existing ASTM methods for VOC analysis from a precision standpoint in which 10% or better reproductibility is desired. The 10% allowance presently in use by many air quality agencies should be replaced by a sliding tolerance scale which reflects the specific parameters of coating formulations.
We suggest that the EPA and ASTM consider round-robin testing of the Cal Poly distillation method to confirm the results obtained in this study and to test the potential broader applicabillity of the method. We also suggest that Cal Poly evaluate extraction-dissolution water analysis (e.g., the Golton Method) and compare it against the distillation method in terms of accuracy, precision, and ease of use. The LASCT intends to initiate further studies to determine if the Cal Poly water method will reduce inaccuracies potentially caused by substances such as ammonia, ionic compounds, and additives, such as melamines and certain pigments. |
| Note de contenu : |
- CAL POLY WATER METHOD : Procedure - Sample - Standard - Analysis and calculation
- VOC VALUES OBTAINED WITH KNOWN SAMPLES
- PREPARATION OF SAMPLES FOR ROUND-ROBIN ANALYSIS
- ROUND-ROBIN DISCUSSION
- CALCULATION OF THE VOC CONTENT
- FORMULA FOR CALCULATION OF COATING VOC CONTENT |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18513 |
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 67, N° 841 (02/1995) . - p. 53-59
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VOC testing comparison : EPA method 24 versus the cal poly method in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 67, N° 841 (02/1995)
