Joe O. Boison

Establishing the fitness for purpose of mass spectrometric methods

This report is submitted by a working group sponsored by the ASMS Measurements and Standards Committee. The group responded to a 1998 opinion piece dealing with mass spectrometry in trace analysis (Bethem, R. A.; Boyd, R. K. J. Am. Soc. Mass Spectrom.1998,9, 643–648) which proposed that the concept of fitness for purpose addresses the needs of a wide range of analytical problems. There is a need to define fitness for purpose within the current context of mass spectrometry and to recommend processes for developing and evaluating methods according to suitability for a particular purpose. The key element in our proposal is for the interested parties to define in advance the acceptable degree of measurement uncertainty and the desired degree of identification confidence. These choices can serve as guideposts during method development and targets for retrospective evaluation of methods. A series of more detailed recommendations are derived from basic principles and also from reviews of current practice. This report highlights some areas where consensus is evident, but also revealed the need for further work in other areas. The recommendations are aimed primarily for the laboratory analyst but we hope they will be accessible to the non-scientist as well. Our goal was to provide a framework that can support informed decisions and foster discussion of the issues, because ultimately it is the responsibility of the analyst to make choices, provide supporting data, and interpret results according to scientific principles and qualified judgment.

A determinative and confirmatory method for residues of the metabolites of carbadox and olaquindox in porcine tissues

Carbadox (CBX) and olaquindox (OLQ) are used in swine feed for growth promotion, to improve feed efficiency, increase the rate of weight gain, control swine dysentery and bacterial enteritis in young swine. In 1991, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) recommended maximum residue limits (MRLs) of 30 and 5mugkg(-1) in liver and muscle tissues of pigs, respectively, based on the concentration of, and expressed as, quinoxaline-2-carboxylic acid (QCA) as marker residue. In 1998, the European Commission (EC) banned the use of CBX and OLQ in food animal production together with four other feed additives, following reports that CBX and desoxycarbadox (DCBX) are suspect carcinogens and mutagens. In 2001, the sale of CBX was halted in Canada. In 2003, JECFA recommended the withdrawal of the previously recommended acceptable daily intake (ADI) and MRLs and concluded that QCA was not a suitable marker residue for CBX, based on new sponsor studies reporting that DCBX, the suspect carcinogen, persisted in animal tissues much longer than had previously been thought. This paper presents a very sensitive LC-MS/MS method that was developed by CFIA scientists for the simultaneous determination and confirmation of DCBX residues at concentrations >/=0.050 ngkg(-1) and QCA and mQCA residues at concentrations >/=0.50 ngkg(-1)in bovine muscle, pork liver and muscle tissues.

Determination of the performance characteristics of a new multi-residue method for non-steroidal anti-inflammatory drugs, corticosteroids and anabolic steroids in food animal tissues

A new LC–MS/MS method was developed for the analysis of 29 veterinary drug residues, spanning three different drug classes, in animal tissues. The procedures used to measure the characteristic performance parameters of the method and the results obtained using fortified blank bovine muscle and kidney tissue are described. For a quantitative and confirmatory method, the characteristic performance parameters to be determined are the limits of quantification, trueness, recovery, precision, selectivity, ruggedness, and stability. The characteristic performance parameters defined for the method will be verified during a validation study by an independent experienced analyst to determine whether the method is suitable for use in a regulatory monitoring and control program for residues of the 29 analytes.

Determination of penicillin G in bovine plasma by high-performance liquid chromatography after pre-column derivatization

A simple, selective, and sensitive liquid chromatographic method with ultraviolet detection was developed for the analysis of penicillin G in bovine plasma. The assay utilizes a simple extraction of penicillin G from plasma (with a known amount of penicillin V added as internal standard) with water, dilute sulphuric acid and sodium tungstate solutions, followed by concentration on a conditioned C18 solid-phase extraction column. After elution with 500 microliters of elution solution, the penicillins are derivatized with 500 microliters of 1,2,4-triazole-mercuric chloride solution at 65 degrees C for 30 min. The penicillin-mercury mercaptide complexes are separated by reversed-phase liquid chromatography on a C18 column. The method, which has a detection limit of 5 ng/ml (ppb) in bovine plasma, was used to quantitatively measure the concentrations of penicillin G in plasma of steers at a series of intervals after the intramuscular administration of a commercial formulation of procaine penicillin G.

Evaluation of high-field asymmetric waveform ion mobility spectrometry mass spectrometry for the analysis of the mycotoxin zearalenone

A high-field asymmetric waveform ion mobility spectrometry (FAIMS)-based method for the determination of the mycotoxin zearalenone (ZON) and its metabolites alpha-zearalenol (alpha-ZOL), beta-zearalenol (beta-ZOL), and beta-zearalanol (beta-ZAL), in a cornmeal (maize) matrix is described. Detection limits achieved using the FAIMS device coupled with electrospray ionization (ESI) and mass spectrometric (MS) detection are 0.4 ng mL(-1) for ZON and 3 ng mL(-1) for alpha-ZOL+beta-ZOL, and beta-ZAL. This represents a significant improvement when compared to detection limits determined using ESI-MS or ESI-tandem mass spectrometry (MSMS) analytical methods. The developed flow-injection (FIA)-ESI-FAIMS-MS method was applied to reference materials ERM-BC-716 and ERM-BC-717 certified for ZON and excellent agreement with the certified values was observed.

High Performance Liquid Chromatographic Determination of Tylosin in Bovine Muscle, Kidney and Liver

Abstract A method is described for the determination of the residual macrolide antibiotic, tylosin, in bovine muscle, kidney, and liver by high performance liquid chromatography. Tylosis was extracted from the tissues with dichloromethane, concentrated on a silica gel solid phase extraction cartridge, and analysed using a reversed-phase C18 column, with UV detection at 280 nm and a mobile phase of 0.005 M ammonium dihydrogen phosphate-acetonitrile-methanol (8:72:20) (v/v/v). The method, which has a detection limit of 15 ng/g in kidney, liver, and muscle, was validated by demonstrating that it is accurate, precise, and reproducible and provides high recovery from tissues fortified with tylosin. Author to whom correspondence and reprint requests should be directed

Pharmacokinetics of tilmicosin in equine tissues and plasma

The macrolide antibiotic tilmicosin has potential for treating bacterial respiratory tract infections in horses. A pharmacokinetic study evaluated the disposition of tilmicosin in the horse after oral (4 mg/kg) or subcutaneous (s.c.) (10 mg/kg) administration. Tilmicosin was not detected in equine plasma or tissues after oral administration at this dose. With s.c. injection, tilmicosin concentrations reached a maximum concentration of approximately 200 ng/mL in the plasma of the horses. Tilmicosin concentrations in plasma persisted with a mean residence time (MRT) of 19 h. Maximum tissue residue concentrations (C(max)) of tilmicosin measured in equine lung, kidney, liver and muscle tissues after s.c. administration were 2784, 4877, 1398, and 881 ng/g, respectively. The MRT of tilmicosin in these tissues was approximately 27 h. Subcutaneous administration of tilmicosin resulted in severe reactions at the injection sites.

Review: Application of High Resolution Mass Spectrometry to Monitor Veterinary Drug Residues in Aquacultured Products.

High resolution MS (HRMS) instruments provide accurate mass measurements. With HRMS, virtually an unlimited number of compounds can be analyzed simultaneously because full-scan data are collected, rather than preselected ion transitions corresponding to specific compounds. This enables the development of methods that can monitor for a wide scope of residues and contaminants in aquacultured fish and shellfish including antibiotics, metabolites, and emerging contaminants. Applications of HRMS to the analysis of veterinary drug residues in aquacultured products are summarized in this review including methods for screening, quantifying, and identifying drug residues in these matrixes. The use of targeted, semi-targeted, and nontargeted analysis of HRMS data and the implications to the global aquaculture industry are also reviewed.

A Review of Aquaculture Practices and Their Impacts on Chemical Food Safety from a Regulatory Perspective.

Aquaculture is currently one of the most rapidly growing food production industries in the world. The increasing global importance for this industry stems primarily from the fact that it is reducing the gap between the supply and demand for fish products. Commercial aquaculture contributes significantly to the economies of many countries since high-value fish species are a major source of foreign exchange. This review looks at the aquaculture industry, the issues raised by the production of fish through aquaculture for food security, the sustainability of the practice to agriculture, what the future holds for the industry in the next 10-20 years, and why there is a need to have available analytical procedures to regulate the safe use of chemicals and veterinary drugs in aquaculture.

Determination of trimethoprim in bovine serum by high-performance liquid chromatography with confirmation by thermospray liquid chromatography—mass spectrometry

A high-performance liquid chromatographic (HPLC) method with a detection limit of 5 ng/ml was developed for the analysis of trimethoprim in bovine serum. Trimethoprim and the internal standard, ormetoprim, under alkaline conditions, were first extracted into dichloromethane and then back-extracted into dilute sulphuric acid (0.15 M) and cleaned-up on a C18 cartridge. Trimethoprim was quantified on a C18 column using a triethylammonium acetate-acetonitrile-methanol (16:3:1, v/v/v) mobile phase at a flow-rate of 1.5 ml/min, with ultraviolet detection at 225 nm. This method was used to verify the accuracy of test responses obtained with the Brilliant Black Reduction test, a rapid screening method, for trimethoprim levels in the serum of steers treated with Trivetrin. Confirmation of the presence of trimethoprim in the sample extract was obtained by thermospray HPLC-mass spectrometry.