LC-MS/MS Validation of a Residue Analysis Method for Penicillin G and Its Metabolites in Commercial Orange Juice.

Florida citrus depends on a breakthrough in the fight against citrus greening disease. Of the antibiotics used to treat this disease, penicillin G has been one of the most effective. Because orange fruit grown in the state of Florida are mainly used to produce orange juice, we have validated an ultra-HPLC tandem MS method to screen for penicillin G and its metabolites (penillic and penilloic acids) at the chemical residue level after treatment. In this method, three spike levels (0.25, 1, and 20 ng/g) were tested in triplicate. Absolute recoveries for penillic and penilloic acids were 60-75% depending on the matrix used, whereas corrected recoveries of penicillin G using an isotopically labeled internal standard were ~100%. Two product ion transitions per analyte were required for identification, which contributes to a high degree of selectivity.

Identification of Penicillin G Metabolites under Various Environmental Conditions Using UHPLC-MS/MS.

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., Thermo Q Exactive Orbitrap and Sciex 6500 QTrap). Our data show that under acidic and alkaline conditions, penicillin G at 100 ng/mL degrades quickly, with a determined half-life time of approximately 2 h. Penillic acid, penicilloic acid, and penilloic acid are found to be the most abundant metabolites of penicillin G. These major metabolites, along with isopenillic acid, are found when penicillin G is used for treatment of citrus greening infected trees. The findings of this study will provide insight regarding penicillin G residues in agricultural and biological applications.

LC-MS/MS Method for the Determination and Quantitation of Penicillin G and Its Metabolites in Citrus Fruits Affected by Huanglongbing.

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 0.1, 0.25, 1, and 10 ng/g. Absolute recoveries for penillic acid and penilloic acid were 50-75% depending on the matrix used. The limit of detection (LOD) of penicillin G and its metabolites was found to be 0.1 ng/g when 2 g of citrus was extracted. This method is useful in determining residue levels of penicillin G and its metabolites in citrus trees infected with huanglongbing bacteria after antibiotic treatment.

Sampling and sample processing in pesticide residue analysis.

Proper sampling and sample processing in pesticide residue analysis of food and soil have always been essential to obtain accurate results, but the subject is becoming a greater concern as approximately 100 mg test portions are being analyzed with automated high-throughput analytical methods by agrochemical industry and contract laboratories. As global food trade and the importance of monitoring increase, the food industry and regulatory laboratories are also considering miniaturized high-throughput methods. In conjunction with a summary of the symposium "Residues in Food and Feed - Going from Macro to Micro: The Future of Sample Processing in Residue Analytical Methods" held at the 13th IUPAC International Congress of Pesticide Chemistry, this is an opportune time to review sampling theory and sample processing for pesticide residue analysis. If collected samples and test portions do not adequately represent the actual lot from which they came and provide meaningful results, then all costs, time, and efforts involved in implementing programs using sophisticated analytical instruments and techniques are wasted and can actually yield misleading results. This paper is designed to briefly review the often-neglected but crucial topic of sample collection and processing and put the issue into perspective for the future of pesticide residue analysis. It also emphasizes that analysts should demonstrate the validity of their sample processing approaches for the analytes/matrices of interest and encourages further studies on sampling and sample mass reduction to produce a test portion.

Reported prevalence and quantitative LC-MS methods for the analysis of veterinary drug residues in honey: a review.

Insect pollination increases the value and productivity of three-quarters of crop species grown for food. Declining beehive health in commercial apiaries has resulted in numerous reports from government laboratories worldwide of contamination with antimicrobial chemicals in honey. This review includes pertinent discussion of legislation and events leading to increased government oversight in the commercial honey market. A detailed summary of the variety and prevalence of veterinary drug residues being found in honey as well as a selection of robust quantitative and confirmatory LC-MS methods with an emphasis on those adopted by government testing laboratories are presented.

Analysis of pesticides residues in fresh produce using buffered acetonitrile extraction and aminopropyl cleanup with gas chromatography/triple quadrupole mass spectrometry, liquid chromatography/triple quadrupole mass spectrometry, gas chromatography/ion trap detector mass spectrometry, and GC with a halogen-specific detector.

A rapid and inexpensive multiresidue method for determining pesticides in fruits and vegetables is presented. Extraction of a 15 g sample with 15 mL acetonitrile was followed by buffering with magnesium sulfate, sodium chloride, sodium citrate dihydrate, and disodium citrate. Acidification with formic acid prior to dispersive cleanup with aminopropyl sorbent and magnesium sulfate was used to stabilize base-sensitive pesticides such as chlorothalonil. Extracts were concentrated to 2 g/mL. Analyses were conducted by GC/ion trap detector MS, GC-halogen-specific detector, and LC/triple quadrupole MS. Accuracy and repeatability for 166 compounds in tomato, potato, and cabbage were 70-120% and <20% CV in 85% of the compounds, respectively. Reproducibility over a 4 month period in multiple commodities and analytical conditions was 62-124%, with CVs better than 30% for 91% of the compounds. Supply cost/sample was reduced 66%, and time to extract a batch of 24 samples was reduced by half compared to the prior method that used a 50 g sample, 100 mL acetonitrile, multiple SPE columns, and additional instrumentation. Additional extraction studies were conducted in tomatoes, oranges, and green beans at 4 g/mL using a GC/MS triple quadrupole system with a programmable temperature vaporization inlet. Recoveries of 70-120% were achieved in 93% of all compounds in green beans, 95% in tomatoes, and 97% in oranges.