Experimental and theoretical study on dissociative photoionization of cyclopentanone

Abstract

The dissociative photoionization of cyclopentanone was investigated by means of a reflectron time-of-flight mass spectrometer (RTOF-MS) with tunable vacuum ultraviolet synchrotron radiation in the photon energy range of 9.0—15.5 eV. The photoionization efficiency (PIE) curves for molecular ion and fragment ions were measured. The ionization energy of cyclopentanone was determined to be 9.23±0.03 eV. Fragment ions from the dissociative photoionization of cyclopentanone were identified as C5H7O+, C4H5O+, C4H8+/C3H4O+, C3H3O+, C4H6+, C2H4O+, C3H6+, C3H5+, C3H4+, C3H3+, C2H5+ and C2H4+. With the aid of the ab initio calculations at the ωB97X-D/6-31+G(d,p) level of theory, the dissociative mechanisms of C5H8O+ are proposed. Ring opening and hydrogen migrations are the predominant processes in most of the fragmentation pathways of cyclopentanone.

Comparison of methods for detecting protein extracted from excess activated sludge

“…The smaller the RSD is, the higher the accuracy of the method. The precisions of the three determination methods for the sludge protein obtained by different hydrolysis processes were all less than 0.05, which meets the experimental requirements of precision (Li and Zhang, 2000).…”

“…BSA was used as the standard protein, and standard addition recovery tests were performed to calculate the recovery rate. Studies have shown that a recovery rate of standard addition between 95% and 105% meets the test requirements (Li and Zhang, 2000). As seen from the Supplementary Information and table A.2, the recovery rates of both the Lowry and BCA methods were between 95% and 105% for the protein solutions obtained by all hydrolysis methods, indicating that the accuracy and reliability of the Lowry and BCA methods were excellent; in contrast, the recovery rate of the Bradford method had a large deviation and did not indicate high credibility in determining the protein content in sludge.…”