A quantitative method for residues of macrolide antibiotics in porcine kidney by liquid chromatography/tandem mass spectrometry.

An LC/MS/MS-based multiresidue quantitative method was developed for the macrolides erythromycin A, neospiramycin I, oleandomycin, spiramycin I, tilmicosin, and tylosin A in porcine kidney tissues. The Canadian Food Inspection Agency (CFIA) had as part of its analytical scope an LC/UV method for quantification of residues of two macrolide antibiotics, tilmicosin and tylosin A, in the kidney, liver, and muscle of cattle, swine, and poultry. The method could not reliably detect concentrations below 10 microg/kg. To increase the scope of the CFIA's analytical capabilities, a sensitive multiresidue quantitative method for macrolide residues in food animal tissues was required. Porcine kidney samples were extracted with acetonitrile and alkaline buffer and cleaned-up using silica-based C18 SPE cartridges. Sample extracts were analyzed using LC/MS/MS with positive electrospray ionization. Fitness for purpose was verified in a single-laboratory validation study using a second analyst. The working analytical range was 5 to 50 microg/kg. LOD and LOQ were 0.5 to 0.6 microg/kg and 1.5 to 3.0 microg/kg, respectively. Limits of identification were 0.5 to 2.0 microg/kg. Relative intermediate precisions were 8 to 17%. Average absolute recoveries were 68 to 76%.

Determination of beta-agonist residues in bovine urine using liquid chromatography-tandem mass spectrometry.

A multiresidue method was developed and validated to screen bovine urine samples for 10 beta-2-adrenergic agonistic drugs--brombuterol, cimaterol, clenbuterol, clenpenterol, isoxsuprine, mabuterol, ractopamine, ritodrine, salbutamol, and tulobuterol--at the 2 microg/L level. The method is also quantitative in the range of 1 to 4 microg/L for all analytes except salbutamol. The procedure uses enzymatic digestion, liquid-liquid extraction, and cleanup on solid-phase extraction columns, followed by detection using a liquid chromatograph-tandem quadrupole mass spectrometer operated in the positive-ion atmospheric pressure chemical ionization multiple-reaction monitoring mode. Method validation included assessment of recoveries, repeatabilities, linearity of responses, decision limits, and detection capabilities. Overall average recoveries ranged from 70-91%; recoveries were generally lower for salbutamol. The decision limits ranged from 0.4-1.0 microg/L, and detection capabilities from 0.6-1.7 microg/L.

Determination of beta-agonists in liver and retina by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the determination of bromobuterol, cimaterol, clenbuterol, clenpenterol, hydroxymethylclenbuterol, isoxsuprine, mabuterol, ractopamine, ritrodrine, salbutamol, terbutaline, and tulobuterol residues in bovine liver and retina is reported. This procedure uses enzymatic digestion, liquid-liquid extraction, and cleanup on Oasis HLB solid-phase extraction cartridges, followed by determination of the residues by LC-tandem quadrupole MS using atmospheric pressure chemical ionization in the positive ion mode. Overall average recoveries ranged from 23 to 76% for liver and 34 to 77% for retina. The mean values for samples fortified at levels between 0.5-2.0 microg/kg (liver) and 5-20 microg/kg (retina) agreed within 98-118% of the spiked levels, with coefficients of variation ranging from 6 to 20%. The decision limits, CCalpha, ranged from 0.1 to 0.3 microg/kg for liver, 1-3 microg/kg for retina, and detection capabilities, CCbeta, from 0.2-0.5 microg/kg for liver and 2-5 microg/kg for retina.

A review of analytical methods for the determination of sulfolane and alkanolamines in environmental studies.

Sulfolane and alkanolamines are used extensively in the processing of sour natural gases. Over many years of operation, there have been inadvertent leaks of these chemicals to groundwater and wetlands surrounding gas processing facilities, leading to uptake by vegetation. Because sulfolane and alkanolamines are extremely water-soluble, their analysis has presented challenges, particularly requirements for suitable extraction from biological matrixes and soil, along with sensitive detection using commonly available instrumentation. Analytical methods usually use gas chromatography or liquid chromatography with a variety of detector systems. Sample preparation techniques may include extraction with organic solvents, water, or a combination of these. In some cases, direct aqueous injections have been used. Derivatization of alkanolamines has been used to improve the chromatographic separations and detection. More recent procedures, using positive-ion electrospray ionization mass spectrometry (MS), have been useful for the confirmation of uptake of the alkanolamines and transformation products by wetland vegetation. Future developments will likely center on further MS analyses for identification of metabolites and transformation products in aquatic environments.

Validation of screening method for residues of diethylstilbestrol, dienestrol, hexestrol, and zeranol in bovine urine using immunoaffinity chromatography and gas chromatography/mass spectrometry.

A method was developed, using commercially available immunoaffinity chromatography cleanup cartridges, followed by detection by gas chromatography/mass spectrometry, to screen for residues of the hormone growth promotants diethylstilbestrol, dienestrol, hexestrol, and zeranol in bovine urine. The single-laboratory, in-house validation included assessment of recoveries, repeatability, linearity of response, detection capability, and specificity (cross-reactivity) with a suite of antibiotics and other hormonal growth promotants. The method was validated for screening at a target concentration of 2.0 microg/L in urine. The detection capabilities for the analytes were diethylstilbestrol, 0.24; dienestrol, 0.15; hexestrol, 0.84; and zeranol, 0.28 microg/L.

Performance characterization of a quantitative liquid chromatography-tandem mass spectrometric method for 12 macrolide and lincosamide antibiotics in salmon, shrimp and tilapia.

This paper describes an extension and performance characterization of a quantitative confirmatory multi-residue liquid chromatography-tandem mass spectrometric method for residues of macrolide and lincosamide antibiotics, originally validated for application to bovine kidney tissues, to tissues of salmon, shrimp and tilapia. The 12 analytes include clindamycin, erythromycin A, gamithromycin, josamycin, lincomycin, neospiramycin 1, oleandomycin, pirlimycin, spiramycin 1, tildipirosin, tilmicosin and tylosin A. The limit of detection was 0.5 µg/kg. Within-laboratory precision evaluated over the analytical range of 5.0-50.0 µg/kg ranged from 4 to 17%. The accuracy of the method ranged from 80 to 112%. Recoveries ranged from 47 to 99% with all but one recovery above 60%. This is the first report of a quantitative confirmatory method for gamithromycin, pirlimycin and tildipirosin in fish and shrimp.

Quantitative screening of stilbenes and zeranol and its related residues and natural precursors in veal liver by gas chromatography-mass spectrometry.

An existing gas chromatography-mass spectrometry-based quantitative screening method for the regulatory analysis of the resorcylic acid lactones zeranol, taleranol, and zearalanone and the stilbene anabolic steroids diethylstilbestrol and dienestrol was extended to include natural precursors of zeranol (zearalenone, alpha-zearalenol, and beta-zearalenol) in veal liver. No changes in sample preparation were required; the instrumental conditions were selected to effect a suitable chromatographic separation and detection of the analytes. Validation experiments were performed to verify the performance and applicability of the extended method for the quantitative screening of the original and additional analytes in veal liver in the concentration range from 0.5 to 2.0 microg/kg. The limits of detection were 0.08-0.19 microg/kg. The limits of quantitation were 0.27-0.64 microg/kg. Recoveries were 29-67%. Combined relative measurement uncertainty estimates were 6-21%.

Spatial patterns of natural polycyclic aromatic hydrocarbons in sediment in the lower Athabasca River.

The Athabasca Oil Sands is one of the four natural oil sands deposits in Northern Alberta, Canada, and are by far the largest oil sand deposit in North America, covering an area of 46,000 km2. Sediment samples were collected from the bed and bank of several tributaries that have naturally occurring exposures of oil sand material. Oil sand deposited along the lower Athabasca River, more than 100 km downstream of naturally occurring oil sand exposures, were also sampled. The levels of alkylated polycyclic aromatic hydrocarbons (PAHs) in samples collected from these various locations ranged from not detected to almost 50 ppm. Using dibenzothiophene/chrysene (C2/D2 vs. C3/D3) double ratio plots, it is possible to approximate the relative degree of degradation or weathering of the PAHs from these various sediment deposits along the lower Athabasca River and its tributaries. Similarly a plot of dibenzothiophene/phenanthrene (D2/P2 vs. D3/P3) indicate the possible origins of the oil. A combination of these plots, D3/P3 vs. D3/C3, was particularly useful in identifying weathering characteristics of different sources of the oil. Comparison of alkylated PAH distributions between the lower Athabasca River and the tributaries show slight differences consistent with different petrogenic sources and/or different weathering patterns.