engleski

Monitoring the impact of analytical procedures on the formation of p,p '-dichlorobenzophenone (DCBP)-Dicofol degradation product

Dicofol (trade name Kelthane) is known to be easly degradable to p, p'-dichlorobenzophenone (DCBP) during various analytical procedures such as GC-injection and matrix storage. The aim of this paper is to verify which analytical procedures contribute most to the creation of DCBP in routine analysis. In the laboratory the incidence of DCBP was observed during routine analysis samples of fruits and vegetables prepared with Quechers method using acidified Acetonitrile (1% H2So4) and without further clean up on dSPE. For the purpose of monitoring Dicofol degradation product (DCBP) method has been created that contains transitions 250>139 m/z and 250>215 m/z corresponding to DCBP. Dicofol standards were prepared by adding standard to the orange matrix and protecting with analyte protectant (API) mix. The orange matrix was prepared by the Quechers method according to the method EN 15662 without further dSPE clean up. The standards made in the matrix were stored in a freezer at -20 °C. Analyzes were performed on a 7010 GC/MS Agilent triple quadruple, using ultra inert dimpled liner in multi mode (MMI) inlet. Over time the incidence of DCBP in the condition of a clean instrument (0-20 analysis) and a contaminated instrument (> 20 analysis) was monitored. Further monitoring was performed performing analysis with clean liner (first anlysis) and contaminated liner (after 20 analysis). The response of DCBP was also followed in the newly prepared standards (same day analysis) matrix match solution and the ones that was stored in freezer over the time (7 days). The response for DCBP using clean instrument and the response using contaminated instrument was constant with RSD 14.3%. The results showed that there was no significant difference in DCBP generation when analyzed on a clean and contaminated instrument. The diference in response of DCBP using clean liner (first analysis) or contaminated liner was even smaller with RSD 6.25%. There were no significant differences in the analyzes performed using a clean or contaminated liner. Conducted DCBP monitoring showed the most significant differences in signal response with RSD 73, 4% when analyzing newly prepared (same day analysis) standard matrix solutions and older prepared solutions (7 days). This experiment proved that the residence time in the matrix had the greatest influence on the formation of Dicofol degradation product (DCBP).

dicofol, DCBP, degradation

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