Multiresidue method for detection of pesticides in beef meat using liquid chromatography coupled to mass spectrometry detection (LC-MS) after QuEChERS extraction

Beef meat is an important food that can be contaminated by pesticides. This study aimed to optimize a multiresidue method for identification and quantification of pesticides in beef meat by liquid chromatography coupled to mass spectrometry detection (LC-MS). The extraction and clean-up procedures were adapted from the QuECHERS method. From the 188 analytes tested, the method was validated as qualitative method for 19 compounds and as quantitative method for 152 compounds. The results were satisfactory, yielding coefficients of variation of less than 20% and recoveries ranging from 70% to 120% and expanded uncertainty of less than 50%. The quantification limit was typically 10 µg kg^?1 (but 25 µg kg^?1 for 12 of the compounds) and the detection limit was 5.0 µg kg^?1. Thirty-two real samples of commercialized beef meat were analyzed without any residual pesticide being found. Thus, the results showed that the multiresidue method for detecting 171 pesticides, using adapted QuECHERS for extraction and LC-MS for detection, is suitable for analyzing beef meat.     

Simultaneous Determination of Dimethenamid,Saflufenacil and their Metabolites in Maize Using a Modified QuEChERS Method and Liquid Chromatography-Tandem Mass Spectrometry

Hydrophilic metabolites of pesticides in food and the environment are seldom analyzed due to the lack of suitable analytical methods. In the present study, a single-run analytical method was developed to determine dimethenamid, saflufenacil and their five metabolites in maize grain and plant. A good linearity was achieved for the matrix-matched calibration curves of the seven analytes with r²?≥?0.9991. The average recoveries of dimethenamid, saflufenacil and their metabolites in maize grain and plant were 70.1–113.8% with inter-day relative standard deviations ≤?21.5%. The limits of detection and quantification for the two herbicides and their metabolites were in the ranges of 0.008–1.4 μg/kg and 0.027–4.7 μg/kg, respectively, in two matrices. The limits of quantification for dimethenamid and saflufenacil in maize grain were below the maximum residue limits proposed by Codex (10 μg/kg). The results from field trials demonstrated the method effective and reliable for monitoring of the target residues in maize.     

High-performance liquid chromatography with fluorescence detection for the determination of nitrofuran metabolites in pork muscle

A simple and sensitive HPLC method with fluorescence detection (HPLC-FLD) is reported for the simultaneous determination of metabolites of four nitrofuran drugs (furazolidone, furaltadone, nitrofurantoin and nitrofurazone) in pork muscle. The method involves acid hydrolysis of the protein-bound drug metabolites and the conjugation of the released side-chains with a novel fluorescence agent 2-hydroxy-1-naphthaldehyde. After liquid–liquid extraction and effective separation of the derivatives on a YMC-Pack Polymer C18 column at 40°C under alkaline conditions, the high fluorescence intensity of these derivatives at emission wavelength λ_em = 463 nm enables their simultaneous determination in pork muscle at concentrations as low as 1 µg kg^?1. The method was validated using blank pork muscle fortified with all four metabolites at 0.5, 1.0 and 2.0 µg kg^?1. Recoveries were > 92.3% with RSDs < 8.5% for all four metabolites. The results obtained with HPLC-FLD and LC-MS/MS methods showed very good agreement for pork muscle samples.     

Analysis of sterigmatocystin in cereals,animal feed,seeds, beer and cheese by immunoaffinity column clean-up and HPLC and LC-MS/MS quantification

A method is reported for the analysis of sterigmatocystin in various food and feed matrices using a commercial sterigmatocystin immunoaffinity column (IAC) for sample clean-up prior to HPLC analysis by UV with mass spectrometric detection (LC-MS/MS). Cereals (wheat, oats, rye, maize and rice), sunflower seeds and animal feed were spiked with sterigmatocystin at levels from 0.75 to 50 µg kg^?1 to establish method performance. Using acetonitrile/water extraction followed by IAC clean-up, and analysis by HPLC with detection at 325 nm, recoveries ranged from 68% to 106%, with repeatability from 4.2% to 17.5%. The limit of quantification with UV detection in these matrices was 1.5 µg kg^?1. For the analysis of beer and cheese the sample preparation prior to IAC clean-up was changed to accommodate the different properties of the matrix, prior to analysis by LC-MS/MS. For beer and cheese spiked at 5.0 µg kg^?1 the recoveries were 94% and 104%, and precision (RSDs) were 1.9% and 2.9% respectively. The limits of quantification by LC-MS/MS in beer and cheese were 0.02 and 0.6 µg kg^?1 respectively. The sterigmatocystin IAC was demonstrated to provide an efficient clean-up of various matrices to enable this mycotoxin to be determined by either HPLC with UV detection or LC-MS/MS.     

Simultaneous analysis and exposure assessment of migrated bisphenol analogues,phenol, and p-tert-butylphenol from food contact materials

ABSTRACT

A simple, rapid, and novel liquid chromatography tandem-mass spectrometry (LC-MS/MS) method was developed and validated to determine levels of eight bisphenol analogues (A, S, F, B, P, AF, AP, and Z), phenol, and p-tert-butylphenol migrated from food contact material (FCM) into food simulants. Method validation showed acceptable values in terms of linearity, precision, and accuracy. The limits of detection and quantification were 0.53–29.6 and 1.77–29.6 μg L^?1, respectively. Water, 4% acetic acid, 50% ethanol, and n-heptane were employed as food simulants for the migration tests, and the proposed method was applied to 234 articles of 11 FCMs including polycarbonate, polyethersulfone, polypropylene, and polyethyleneterephthalate, obtained from domestic markets and manufacturers in Korea. Only phenol was found in the FCMs poly(cyclophexane-1,4-dimethylene terephthalate), polylactide, and thermoplastic polyurethane. Eight bisphenol analogues and p-tert-butyl phenol were not found in any samples. Using the obtained migration results, the estimated daily intake (EDI) of phenol was calculated. Exposure assessments were carried out to compare the EDI with the tolerable daily intake (TDI), showing a low percentage (0.18%) of the TDI reported. This is the first study to examine eight bisphenol analogues and two phenols simultaneously in FCMs using the LC-MS/MS.     

Microwave-assisted derivatisation and LC-MS/MS determination of nitrofuran metabolites in farm-raised prawns (Penaeus monodon)

A new microwave-assisted derivatisation and LC-MS/MS method has been developed for the analysis of nitrofuran metabolites – 3-amino-5-morpholino-methyl-1,3-oxa-zolidinone (AMOZ), 3-amino-2-oxazolidinone (AOZ), 1-aminohydantoin (AHD) and semicarbazide (SEM) – in farm-raised prawns (Penaeus monodon) from the coastal regions of South India. Analysis was carried out by reverse-phase column (Phenomenex Luna C₁₈) with gradient elution using mobile phase A (0.02% acetic acid in water) and mobile phase B (0.02% acetic acid in acetonitrile), at a flow rate of 200 μl min^–1 and an injection volume of 20 μl. Microwave-assisted derivatisation was achieved in 6 min with good recovery. The results showed that the samples collected from Andhra Pradesh and Karnataka contained residues of nitrofuran metabolites in the range from 5.0 to 40 ng g^–1. This work emphasises the importance of ensuring the safety of seafood and that a new method of derivatisation is applicable for the analysis of nitrofuran metabolites in seafood.     

Comparison of multiple methods for the determination of sulphite in Allium and Brassica vegetables

Sulphites are a family of additives regulated for use worldwide in food products. They must be declared on the label if they are present in concentrations greater than 10 mg kg^–1, determined as sulphur dioxide (SO₂). The current US regulatory method for sulphites, the optimised Monier–Williams method (OMW), produces false-positive results with vegetables from the Allium (garlic) and Brassica (cabbage) genera due to extraction conditions that are thought to cause endogenous sulphur compounds to release SO₂. Recently, modifications to the OMW method (2x MW) were published that reportedly reduced this false-positive in garlic. However, no other vegetables from these genera have been investigated. In addition, an LC-MS/MS method was developed for sulphite analysis, but it has not yet been tested with these problematic matrices. Ten vegetable species were analysed using these sulphite methods (OMW titration, OMW gravimetric, 2x MW and LC-MS/MS) to determine the false-positive rate. Sulphite concentrations > 10 mg kg^–1 SO₂ were observed with the OMW analyses. The 2x MW method reduced the measured concentration in unsulphited samples to ≤ 10 mg kg^–1 SO₂ for all matrices analysed. The LC-MS/MS method showed concentrations < 10 mg kg^–1 for the Brassica samples, but only displayed a slight reduction in the Allium matrices. Spiked recovery studies were conducted to determine if these methods can detect added sulphite. The 2x MW had recoveries of 17% and 42% for water and fresh garlic, respectively, and the LC-MS/MS had recoveries of 108%, 125%, 116% and 107% for water, fresh garlic, roasted garlic, and hummus, respectively. The low recoveries of the 2x MW may indicate that sulphur compounds cannot be properly quantified with this method. The ability to eliminate false-positives will enable accurate determination of added sulphite to ensure compliance with sulphite labelling requirements.     

Simultaneous determination of nine acaricides and two metabolites in comb honey by LC/MS/MS

ABSTRACT

We developed a method for the simultaneous determination of acaricides in comb honey using LC/MS/MS. Because methods for honey analysis had not previously been applied to comb honey, we modified three techniques for sample preparation and LC/MS/MS conditions. First, we used a modified QuEChERS method that changed the extraction solution from ethyl acetate to acetonitrile. Second, we replaced the InertSep® MA-1 (30 mg, 1 ml) clean-up cartridge with an Oasis® HLB (60 mg, 3 ml). Third, we changed the ionisation mode from ESI to atmospheric pressure chemical ionisation (APCI). With these modifications, sample matrices had no effect on the identification and quantification of analytes, using an external solvent calibration curve. We verified this new method with nine acaricides and two metabolites on comb honey and honey samples from three different honey origins. The trueness ranged from 74.0 to 99.4%. The relative standard deviation of repeatability (RSD_r) ranged from 0.8 to 14.8% and that of within-laboratory reproducibility (RSD_WR) ranged from 1.3 to 14.8%. All criteria met Japanese validation guidelines. The LOQ was 1.0 μg kg^–1 for all analytes. We applied this method to 10 comb honey and 31 honey samples commercially available in Tokyo. From the results of the analysis of 41 samples, we observed that amitraz remained as N-(2,4-dimethylphenyl)-N-methylformamidine (DMPF) in 9 comb honey and 23 honey samples and that their residual concentrations were less than 20 μg kg^–1. Using this new method, we improved recovery and precision, which enabled precise quantitative determination. Furthermore, the residual amitraz value in honey determined by both this new and the previous method were in good agreement.     

Development of a Quantitative Multi-Mycotoxin Method in Rice, Maize, Wheat and Peanut Using UPLC-MS/MS

Mycotoxins are secondary metabolites produced by fungi, such as Fusarium, Penicillium, and Aspergillus, which are toxic to humans with high risk factors and pose a significant threat to human health. This study was focused mostly on well-known mycotoxins, such as aflatoxins (AFB₁, AFB₂, AFG₁ and AFG₂), fumonisin (FB₁, FB₂), deoxynivalenol (DON), zearalenone (ZON), ochratoxin A, T-2 and HT-2, in grains. The multi-mycotoxin methods developed in this study utilise an analysis of mycotoxin through liquid chromatography tandem mass spectrometry (LC-MS/MS), which can significantly improve sample analysis efficiency. The Myco6in1? immunoaffinity column was used for purification to reduce interference from the substrate. Gradient separation to obtain the best peak shift was conducted using solvent with 0.1 % formic acid in deionised water and methanol, and gradient separation was performed on an ACQUITY BEH C18 column chromatograph. The recovery rate test for each toxin using substrates such as rice, peanut, wheat and maize mostly indicated good average recovery rates between 70 % and 120 % and the coefficient of variation mostly under 15 %. The limits of quantification (LOQ) identified by this method are less than 5 ng/g in most toxins, except for 20 ng/g in FB₁and FB₂. This method can rapidly and simultaneously analyse 11 mycotoxins in 9 min. It can be applied for the practical examination of mycotoxins in food to protect public health.     

Development and validation of an LC-MS/MS method for the simultaneous determination of deoxynivalenol,zearalenone, T-2-toxin and some masked metabolites in different cereals and cereal-derived food

An LC-MS/MS method was developed and validated for the simultaneous determination of deoxynivalenol, zearalenone, T-2-toxin, HT-2-toxin and metabolites, including 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, deoxynivalenol-3-glucoside, α-zearalenol, β-zearalenol, zearalenone-4-glucoside, α-zearalenol-4-glucoside, β-zearalenol-4-glucoside and zearalenone-4-sulfate in maize, wheat, oats, cornflakes and bread. Extraction was performed with acetonitrile/water/acetic acid (79/20/1, v/v/v) followed by a hexane defatting step. After filtration, the extract was evaporated and the residue was redissolved in mobile phase for injection. The mobile phase, which consisted of a mixture of methanol and water with 10?mM ammonium acetate, was adjusted to pH 3 with glacial acetic acid. A sample clean-up procedure was not included because of the low recoveries of free and masked mycotoxins and their differences in polarity. The method allowed the simultaneous determination of 13 Fusarium mycotoxins in a one-step chromatographic run using a Waters Acquity UPLC system coupled to a Quattro Premier XE mass spectrometer. The method was validated for several parameters such as linearity, apparent recovery, limit of detection, limit of quantification, precision, expanded measurement uncertainty and specificity. The limits of detection varied from 5 to 13?ng?g^?1; those for the limit of quantification from 10 to 26?ng?g^?1. The results of the performance characteristics of the developed LC-MS/MS method were in good agreement with the criteria mentioned in Commission Regulation (EC) No. 401/2006. Thirty samples of a variety of food and feed matrices were sampled and analysed between July 2010 and January 2011.     

Simultaneous determination of three pesticides and their metabolites in unprocessed foods using ultraperformance liquid chromatography-tandem mass spectrometry

We have developed a rapid, multi-compound analytical method for measuring residues of the pesticides thiamethoxam and its metabolite, clothianidin; fipronil and its three metabolites, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl; and pyraclostrobin in unprocessed foods (rice, corn, cucumbers, tomatoes, apples, and bananas) by ultra-performance liquid chromatography coupled to tandem mass spectrometry. Acetonitrile was used as the extraction solvent, and an octadecylsilane-dispersive SPE was used to clean up the analytes, which were then separated through a UPLC HSS T3 column connected to a tandem mass spectrometer via an electrospray ionisation source. The linearity of this method for the target analytes was excellent (R² ≥0.990) in the concentration range of 5–1000 μg kg^–1. The average recoveries of the seven compounds at concentrations of 10, 100, and 1000 μg kg^–1 from six spiked matrix samples ranged from 73.6 to 110.6%, all with RSD values of ≤19.7%. The limit of quantification was 10 μg kg^–1. The method validated the effectiveness of the method for routine monitoring the residue of these pesticides and their metabolites in foods.     

Measurement of ampicillin residue levels in chicken eggs during and after medicated feed administration by LC-MS/MS

A simple and sensitive LC-MS/MS method was developed and validated for the determination of ampicillin (ABPC) in chicken eggs. Residues were extracted by reverse-phase solid-phase extraction. Chromatographic separation was performed using a reverse-phase column with an elution gradient. The limits of detection and quantification were 0.01 and 0.1 ng g^?1, respectively. For the 0.1–50 ng g^?1 concentration range, mean recovery and accuracy values were 93.9–98.5% and 100.2–118.0%, respectively. ABPC residue concentrations in eggs before, during and after 7 days of medicated feeding of maximum dosage (40 mg kg^?1 body weight day^?1) of ABPC were determined with the LC-MS/MS method. The maximum concentration of ABPC in eggs was 3.6 ± 1.7 ng g^?1 (mean ± SD) on the last day of the administration period. Residue concentrations of ABPC in eggs during and after ABPC administration were not over the Japanese maximum residue limit of 0.01 mg kg^?1.     

A Simple and Improved HPLC Method for the Analysis of Dithianon in Red Pepper with Tandem Mass Spectrometry Confirmation

A simple and rapid method was developed for the analysis of dithianon in red pepper using HPLC-UV. Sample extraction was carried out using acidic acetonitrile as a solvent and sodium chloride as a salting out agent. The extract was then purified through solid phase extraction procedure. The method was validated using standard calibration. A linear range of standards were determined with excellent correlation coefficients (r ²) >0.999. Limits of detection and quantification were 0.01 and 0.03 mg/kg, respectively. Recovery was assessed by spiking blank red pepper samples at two different concentrations (0.3 and 1.5 mg/kg) with three replicates. A consistent recovery was determined (72.2 and 79.1 %) according to SANCO guidelines for repeatability, and based on the relative standard deviation which was <4 within 3 days (intra- and inter-days) of experiment. The method was applied to field samples to determine the dissipation and pre-harvest residue interval (PHRL). From the PHRL curve, it can be predicted that if the residual amount of dithianon is below 8.5 mg/kg at 10 days or below 5.51 mg/kg at 7 days before harvest, then the residue of dithianon will be below the MRL during the harvest time. The levels of residues in field samples were confirmed using LC-MS/MS in negative electron spray ionization mode.     

Diazo Coupling Reaction of Catechins and Alkylresorcinols with Diazotized Sulfanilic Acid for Quantitative Purposes in Edible Sources: Method Development and Validation

Catechins and alkylresorcinols are important secondary metabolites distributed in food products, sometimes exploited in quality control and/or as markers. The current methods for their quantitative analysis have some disadvantages such as cost, time consuming, and even insensitive or non-selective. Therefore, suitable, efficient methods are still required. As part of our research on new and rapid methods of analyses in plant and food products, a spectrophotometric method to quantify alkylresorcinols and catechins in plant products was developed and fully validated. The colored product by the diazo coupling between olivetol and catechin with diazotized sulfanilic acid was employed to develop the method. The effect of acid and diazonium salt concentration and the reaction time was analyzed. The method was linear in 0.8–8.3 and 0.6–10.2 μg/mL ranges to olivetol and catechin, respectively. Limit of detection and limit of quantification for olivetol and catechin were 0.253/0.768 and 0.106/0.321 μg/mL, respectively. Precision at intra-day and inter-day levels (relative standard deviation (RSD) 1.3–9.7 %) and accuracy (99.0–104.9 %) were also demonstrated. Additionally, the application of the method to plant samples containing alkylresorcinol or catechins was subsequently evaluated, being comparable with conventionally employed methods. Thus, the method demonstrated to be fast, easy, inexpensive, and reliable for quantifying these kinds of metabolites in food products.     

Assessment of pesticide residues in strawberries grown under various treatment regimes

The dynamics of pesticide residues in strawberries that involved quantification of pesticide residues in ripe fruits after model treatment was evaluated in repeated field trials conducted over 3 years. Sixteen commercial pesticide formulations in various combinations were employed in applications from 7 to 44 days before harvest. Altogether 21 active ingredients and some of their metabolites were determined in treated strawberries using LC-MS and GC-MS methods. Except for propargite, the concentrations of all active ingredients declined below the respective MRLs (Regulation (EC) No. 396/2005); nevertheless, most of the tested fungicides often persisted above the 0.01 mg kg^?1 limit required by baby food producers to avoid the risk of exceeding the ‘baby food limit’ established in Commission Directive 2006/141/EC. On the other hand, residues of the majority of tested insecticides, namely spinosad, pymetrozine, deltamethrin, lambda-cyhalothrin and azadirachtin, declined below this limit.     

An LC-MS/MS-SRM Method for Simultaneous Quantification of Four Representative Organosulfur Compounds in Garlic Products

The quantitative analysis of organosulfur compounds is important for the quality control of various garlic products along with studying their molecular functionality and nutraceutical properties. In this study, a liquid chromatography-tandem mass spectrometry-selected reaction monitoring (LC-MS/MS-SRM) method with electrospray ionization detection was developed and validated for the rapid, simultaneous quantification of four representative organosulfur compounds in garlic: alliin, S-allyl-L-cysteine, γ-glutamyl-S-allyl-L-cysteine, and allicin. Stable SRM transitions were achieved for these compounds under optimized conditions, and the linear range extended from 1 to 2000 ng/mL. The limits of detection and quantification ranged from 0.003 to 0.058 ng/mL and from 0.01 to 0.19 ng/mL, respectively. Excellent recovery and reproducibility at different spiking levels were achieved. The method was successfully applied to the simultaneous quantification of organosulfur compounds in fresh garlic samples. This highly selective and sensitive LC-MS/MS-SRM method is expected to be a useful tool for studying molecular functionality and the quality control of garlic products.     

A Robust Transferable Method for the Determination of Glyphosate Residue in Liver After Derivatization by Ultra-high Pressure Liquid Chromatography–Tandem Mass Spectrometry

Glyphosate determination in liver is challenging due to this particular molecule/matrix combination. Glyphosate is a very polar molecule and liver composition is highly variable between individuals and species. Since 2014, the Multiannual Control Program (MACP) of the European Union (EU) demands to analyse glyphosate in food of animal origin on a voluntary basis. Moreover, this analysis will be mandatory in 2017. This paper describes a robust and easily transferable method for glyphosate quantification in liver of animal origin by means of liquid chromatography–tandem mass spectrometry (LC-MS/MS). An intensive clean-up was used to eliminate matrix interferences and was combined with a derivatization step which ensures good retention of glyphosate on a conventional reverse-phase LC column. This method allows to meet the MACP requirements without a time-consuming change in the set-up of the routinely used LC-MS/MS system. Furthermore, it allows the use of an LC column and mobile phases often used in multi-residue analysis. The analytical method was validated according to the SANCO/12571/2013 criteria. Isotopic dilution was used to quantify glyphosate, leading to mean apparent recoveries of 115 and 101 % for the low (0.025 mg kg^?1) and the high (0.250 mg kg^?1) fortification levels, respectively. At both levels, the relative standard deviation was below 10 %. The limit of quantification of 0.025 mg kg^?1 was found to be satisfactory as it was below the maximum residue level (MRL) value set at 0.050 mg kg^?1 for glyphosate in liver. It is also the lowest MRL for all commodity types.     

Simultaneous determination of aditoprim and its three major metabolites in pigs,broilers and carp tissues,and its application in tissue distribution and depletion studies

Aditoprim (ADP) is a recently developed dihydrofolate reductase inhibitor that has shown promise for therapeutic use in veterinary medicine because of its excellent pharmacokinetic properties. In this study, a sensitive and reliable multi-residue chromatography-ultraviolet (HPLC-UV) method for the quantitative analysis of ADP and its three major metabolites was developed, and the tissue distribution and depletion profiles of ADP and its major metabolites in pigs, broilers and carp were investigated. Edible and additional tissues (heart, lung, stomach, intestine and swim bladder) were collected for analysis at six different withdrawal periods after ADP administration for 7 days. ADP, N-monomethyl-ADP and N-didesmethyl-ADP were detected in almost all tissues in the three species. The liver, kidney and lung showed higher residue concentrations, and the liver showed a longer residue half-life (t_1/2) than other tissues. In the liver, ADP was the most abundant component with the longest persistence. The results suggest that the liver was the residual target tissue and ADP was the marker residue, and the conclusive withdrawal time (WDT) of 20 days in pigs, 16 days in broilers and 25 days in carp was estimated using the assessment methodologies approved by the Joint FAO/WHO Expert Committee on Food Additives (JECFA).     

A Sensitive and Validated Method for Determination of T-2 and HT-2 Toxin Residues in Shrimp Tissues by LC-MS/MS

Accurate analyses of T-2 and HT-2 toxin in aquatic organisms including shrimp are important as these two toxins are increasingly detected in aquatic cereal-based feed. Therefore, the potential for these toxins to enter the human food chain from contaminated fish and shrimp products is very real. A rapid, sensitive, and validated method for simultaneous determination of T-2 and HT-2 toxins was developed using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method following extraction of the two toxins from shrimp tissues with ethyl acetate. This method is simple in that additional solid-phase extraction is not required to isolate and purify the toxins. LC was performed on an analytical Hypersil GOLD column. The mobile phase consisted of methanol and 5 mM ammonium acetate containing 0.1 % formic acid. The MS/MS ion transitions for both the T-2 toxin (484.20?→?214.87) and HT-2 toxin (442.20?→?214.96) were monitored. And the most intense transition ion product (m/z) of T-2 and HT-2 used for quantification on the SRM mode of a mass spectrometer was 304.95 and 262.91, respectively. The results linearly correlated with coefficients >0.9990. The limits of quantification ranged from 0.02 to 0.51 ng·g^?1 and from 0.17 to 4.48 ng·g^?1 for T-2 and HT-2, respectively, depending on the shrimp tissue type. The overall extraction recovery for both toxins ranged between 84 and 111 % with RSD values less than 15.0 %, indicative of good replication. Furthermore, the recovery and precision levels were within the predefined limits (≤15 %) at all concentrations. The application of this method to study the accumulation of T-2 toxin in shrimp showed that it can be successfully used to monitor even very low tissue toxin concentrations. Research is in progress to extend this method for the measurement of T-2 and HT-2 in aquatic foods that enter the human food chain.     

Identification and quantification of lichenysin – a possible source of food poisoning

Lichenysin produced by 53 different Bacillus licheniformis strains has been structurally examined with a qualitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using quadrupole-time-of-flight mass spectrometry. The same lichenysin isoforms are produced from all strains, indicating that the growth conditions have a stronger influence on the lipopeptide production than the genotype. A rapid method for the quantification of lichenysin from bacterial cell cultures with LC-MS/MS after a simple methanol extraction has been refined. For the first time commercially available lichenysin has been used as calibrant, making quantification more accurate. The trueness for C15-lichenysin has been improved to 94% using matrix-matched calibration with lichenysin compared with 30% using solvent calibration with surfactin. The quantitative method was fully validated based on Commission Decision 2002/657/EC. The LOD of the method was below 1 µg g^–1 and the repeatability ranged from 10% to 16%.