Publications by authors named "Mark R Crosswhite"

Article Synopsis
  • Florida's citrus industry is struggling with citrus greening disease, prompting the need for effective treatment methods.
  • Penicillin G, along with its metabolites (penillic and penilloic acids), has proven to be one of the most effective antibiotics for this disease.
  • A validated ultra-HPLC tandem MS method was developed to detect these compounds at low chemical residue levels, showing high selectivity and recovery rates for analysis.
View Article and Find Full Text PDF

In this work, we investigate the stability of penicillin G in various conditions including acidic, alkaline, natural acidic matrices and after treatment of citrus trees that are infected with citrus greening disease. The identification, confirmation, and quantitation of penicillin G and its various metabolites were evaluated using two UHPLC-MS/MS systems with variable capabilities (i.e.

View Article and Find Full Text PDF

In this study, we developed and validated a method for the extraction, identification, and quantitation of penicillin G and its metabolites (penilloic acid and penillic acid) in a variety of citrus fruits by employing sequential liquid/liquid and solid-phase extraction techniques in conjunction with UHPLC-MS/MS. Two product ion transitions per analyte were required for identification, which contributes to a high degree of selectivity. Corrected recoveries of penicillin G using an isotopically labeled internal standard were 90-100% at fortification levels of 0.

View Article and Find Full Text PDF

Extracts of the plant Echinacea purpurea are widely used for medicinal purposes. Effective quality control of these extracts requires rapid methods to determine their chemical composition. A new method for analysis of caffeic acid derivatives and alkamides from Echinacea extracts has been developed.

View Article and Find Full Text PDF