Analysis of thyreostatic drugs in thyroid samples by ultra-performance liquid chromatography tandem mass spectrometry detection

A method based on ultra-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry for the determination of six thyreostatic drugs in thyroid tissue has been optimised and validated in accordance with the Decision 2002/657/EC. Samples are extracted with methanol and the extracts cleaned-up on silica cartridges. The recoveries range from 40% for 6-phenyl-2-thiouracil to 79% for 2-thiouracil. Quantification is carried out with blank tissue samples spiked with the analytes in the range 25-500 microg kg(-1). 5,6-Dimethyl-2-thiouracil is used as internal standard. CCalpha and CCbeta are in the ranges 4.3-16.1 microg kg(-1) and 8.7-20.7 microg kg(-1), respectively. Accuracy, expressed as percentage of error, is lower than 6% and relative standard deviation in reproducibility conditions falls between 5.6 and 10.3%. Nowadays, the proposed method is routinely implemented in the laboratory of the Agència de Salut Pública de Barcelona and allows processing of up to 20 samples per day.     

An analytical method to screen for six thyreostatic drug residues in the thyroid gland and muscle tissues of food producing animals by liquid chromatography with ultraviolet absorption detection and liquid chromatography/mass spectrometry

A method was developed and validated to screen for residues of the thyreostatic drugs, tapazole (TAP), mercaptobenzimidazole (MBI), thiouracil (TU), methylthiouracil (MTU), propylthiouracil (PrTU), and phenylthiouracil (PhTU) in bovine, equine, ovine, and porcine thyroid and muscle tissues at concentrations > or = 5 ng/g using 2-methoxy-mercaptobenzimidazole (MeMBI) and dimethylthiouracil (DMTU) as internal standards. In this method, the drugs were solvent extracted from thyroid and muscle tissue and cleaned up on an amino-propyl solid-phase extraction (SPE) cartridge. The unretained fraction containing TAP and MBI and the internal standard, MeMBI, was collected as Fraction 1. The retained fraction containing TU, MTU, PrTU, PhTU, and the internal standard, DMTU, was eluted with 3% acetic acid-isopropanol as Fraction 2. Fraction 1 was further cleaned up on an alumina B SPE cartridge and analyzed by gradient elution on a C18 high-performance liquid chromatography (HPLC) column with ultraviolet detection at wavelengths of 255 and 300 nm. Fraction 2 was taken to dryness, derivatized with 4-chloro-7-nitrobenzo-2-furazan at pH 8, and analyzed by gradient elution on a C18 LC column with mass spectrometry (MS) detection. Any "presumptive positive" test results were submitted for further analysis by LC/MS/MS. The validated method was applied to the analysis of over 300 thyroid tissue samples.     

Method for the analysis of thyreostats in meat tissue using gas chromatography with nitrogen phosphorus detection and tandem mass spectrometric confirmation

An analytical method not requiring a mercury column cleanup step is described for the isolation and detection of four thyreostatic agents in meat tissue. The use of these growth promotants in livestock has been banned by regulatory agencies. The meat tissue is homogenized with acetonitrile-water, centrifuged, and the supernatant is partitioned with petroleum ether. The acetonitrile-water is concentrated and then passed through a silica-gel column. The solvent is then removed and the residue derivatized with N-methyl-N-(trimethylsilyl)-trifluoroacetamide. The total amount of organic solvent used for the analysis is merely 35 mL. The derivatized thyreostats are detected and quantitated by gas chromatography (GC) equipped with a nitrogen-phosphorus detector. Percent recoveries from fortified meat tissue (n = 6) at the 0.1-microg/g (parts per million) level are 93.5 +/- 2.9 for 2-thiouracil, 90.3 +/- 3.0 for tapazole, 87.5 +/- 2.9 for 6-methyl-2-thiouracil, and 85.1 +/- 5.8 for 6-n-propyl-2-thiouracil. For the confirmation of analyte identities, GC-tandem mass spectrometry with an ion-trap instrument is used. The estimated minimum level for a reliable measurement is 0.050 microg/g in meat tissue.     

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%.     

Liquid chromatography tandem mass spectrometry with ion trap and triple quadrupole analyzers for determination of thyreostatic drugs in urine and muscle tissue

Liquid chromatography tandem mass spectrometry methods were developed and validated to screen for and confirm residues of the thyreostatic drugs: tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil in bovine and porcine urine and muscle tissues using dimethylthiouracil as internal standard. Thyreostats were extracted from urine samples with diethyl ether after derivatisation with 3-iodobenzylbromide in basic medium (pH 8.0) and analyzed by gradient elution on a Nucleosil C18 column with ion trap mass spectrometry detection using an electrospray source and triple quadrupole MS detection with turbo spray source. Thyreostats were extracted from muscle tissue with methanol, the denaturation of matrix protein was performed and then the same steps as for the urine samples were carried out. The methods were validated in accordance with the Commission Decision 2002/657/EC. Good thyreostats recoveries were obtained (from 82% to 117%) as well as acceptable within-lab reproducibility. The values of the decision limit CCα and the detection capability CCβ of five thyreostatic drugs are found to be below the recommended concentration set at 10 μg L(-1) (kg(-1)). The results of the validation demonstrate that liquid chromatography mass spectrometry with ion trap detection does not meet the criteria for confirmation for some thyreostats and therefore was applied for screening purpose only.     

Determination of residues of tricaine in fish using liquid chromatography tandem mass spectrometry

A liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of residues of the anaesthetic tricaine mesilate (MS222) in fish tissues is described. Residues were extracted from homogenized tissues with McIllvaine buffer/methanol and purified over a C18 solid-phase extraction column followed by LC-MS/MS analysis. In the multiple-reaction monitoring mode of the mass spectrometer, chromatograms were recorded by monitoring the m/z 166-->m/z 138 and m/z 166-->m/z 94 transitions for quantification and confirmation of the residues in the finfish matrix, respectively. Recoveries were in the range of 67%+/-10% (n=6) for tilapia at 2 microg kg(-1), 95%+/-7% (n=6) at 2 microg kg(-1) in salmon and 92%+/-3% (n=5) for trout at 2.5 microg kg(-1). The limits of detection were 0.5, 0.6 and 0.6 microg kg(-1) in trout, salmon and tilapia, respectively. No residues of tricaine were found in eight sampled aquacultured fish (salmon and trout) bought from the local market.     

Application of gas chromatography-triple quadrupole mass spectrometry in the quantification-confirmation of pesticides and polychlorinated biphenyls in eggs at trace levels

A new multiresidue method has been developed and validated for the simultaneous analysis of 57 compounds, including organochlorine and organophosphorus pesticide residues (OCPs and OPPs) and polychlorinated biphenyls (PCBs), in eggs at trace levels by gas chromatography coupled to triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Egg samples were extracted by a simple and fast matrix solid phase dispersion (MSPD) procedure using C18 as sorbent, and ethyl acetate and acetonitrile saturated in n-hexane (85:15, v/v) as elution solvent with a simultaneous clean up with Florisil in-line. The QqQ analyzer acquired data in selected reaction monitoring (SRM) mode, permitting both quantification and confirmation in a single injection with a running time reduced up to 17.70 min. Recovery was in the range of 70-110% and 70-106% at 15 and 50 microg/kg, respectively. Precision values expressed as relative standard deviation (RSD) were lower than 20%. Linearity in the range of 10-150 microg/kg provided determination coefficients (R(2)) higher than 0.98 for all compounds. Limits of detection (LODs) for pesticides were < or =2.25 microg/kg and limits of quantification (LOQs) ranged from 0.02 to 7.78 microg/kg. LODs for PCBs were < or =0.41 microg/kg and LOQ were < or =0.71 microg/kg. The method was applied to real samples. Endosulfan sulphate and p,p'-DDE were found in two samples at concentrations below the first calibration level.     

Validated method for determination of ultra-trace closantel residues in bovine tissues and milk by solid-phase extraction and liquid chromatography-electrospray ionization-tandem mass spectrometry

A liquid chromatographic-electrospray ionisation-tandem mass spectrometry method (LC-ESI-MS/MS) with solid extraction was developed and validated for the detection and determination of closantel residues in bovine tissues and milk. An acetonitrile-acetone mixture (80:20, v/v) was used for one-stage extraction of closantel residues in bovine tissues and milk samples, and the extract was cleaned by solid phase extraction with Oasis MAX cartridges. The mass spectrometer was operated in multiple reactions monitoring mode with negative electrospray interface. The limits of detection in different matrices were in the range of 0.008-0.009 microg/kg. The overall recoveries for bovine muscle, liver, kidney and milk samples spiked at four levels including MRL were in the range of 76.0-94.3%. The overall relative standard deviations were in the range of 3.57-8.61%. The linearity is satisfactory with a correlation coefficient (r(2)) of 0.9913-0.9987 at both concentration ranges of 0.02-100 microg/kg and 200-5000 microg/kg. The method is capable of identifying closantel residues at > or =0.02 microg/kg levels and was applied in the determination of closantel residues in animal origin foods.     

Determination of pesticide residues in honey by single-drop microextraction and gas chromatography

A novel, simple, and rapid single-drop microextraction (SDME) procedure combined with GC has been developed, validated, and applied for the determination of multiclass pesticide residues in honey samples. The SDME was optimized using a Plackett-Burman screening design considering all parameters that may influence an SDME procedure and a consequent central composite design to control the parameters that were found to significantly influence the pesticide determination. The developed analytical method required minimal volumes of organic solvents and exhibited good analytical characteristics with enrichment factors ranging from 3 for alpha-endosulfan to 10 for lindane, procymidone, and captan and method quantification limits ranging from 0.03 microg/kg for phosalone to 10.6 microg/kg for diazinon. The relative recoveries obtained ranged from 70.8% for captan to 120% for fenarimol, and the precision (RSD) ranged from 3 to 15%. The proposed SDME procedure followed by GC with an electron capture detector for quantification and GC/MS for identification was applied with success to the analysis of 17 honey samples. Monitoring results indicated a low level of honey contamination by diazinon, chlorpyrifos-ethyl, procymidone, bromopropylate, and endosulfan (alpha-, beta-, and endosulfan sulfate) residues that were far below the maximum residue limit values specified by the European Union for endosulfan (10 microg/kg) and bromopropylate (100 microg/kg) in honey samples.     

High-throughput GC/MS and HPLC/MS/MS techniques for the multiclass, multiresidue determination of 653 pesticides and chemical pollutants in tea

An efficient and sensitive method has been established for simultaneous determination of 653 pesticides in teas by GC/MS and HPLC/MS/MS. The method involved extraction with acetonitrile followed by cleanup using Cleanert-TPT SPE and subsequent identification and quantitation of 490 pesticides by GC/MS and 448 pesticides by HPLC/MS/ MS. The LODs for pesticides determined by GC/MS were between 1.0 and 500 microg/kg, and those determined by HPLC/MS/MS were between 0.03 and 4820 microg/kg. At the low fortification levels of 0.01-100 microg/kg, the average recoveries of 94% of the pesticides determined by GC/MS were between 60 and 120%, 77% of which had an RSD below 20%. For 91% of pesticides determined by HPLC/MS/MS, the average recoveries were between 60 and 120%, 76% of which had an RSD below 20%. The paper also reports a novel SPE column, Cleanert TPT, which comprised graphitized carbon black (PestiCarb), polyamine silica, and amide polystyrene for purifying the tea samples. The results indicated good repeatiblity and reproducibility.     

Quantitative liquid chromatography/tandem mass spectrometry determination of chloramphenicol residues in food using sub-2 microm particulate high-performance liquid chromatography columns for sensitivity and speed

The use of chloramphenicol (CAP)--a highly effective broad-spectrum antibiotic used in animal husbandry--is banned in many countries. Therefore, a very low minimum required performance limit (MRPL) of 0.3 microg/kg CAP in meat for human consumption has been defined. Analytical methods capable of quantifying and confirming such low residue levels require sophisticated instrumentation. Preferably sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) or gas chromatography/mass spectrometry (GC/MS) methods have been used. This paper suggests the use of sub-2 microm particulate high-performance liquid chromatography (HPLC) columns to gain additional sensitivity and improve resolution as well as speed. Depending on the operating conditions, higher chromatographic resolution and speed can be obtained at the price of a significantly increased operating pressure, requiring dedicated LC equipment. A 3-4-fold overall improvement of the signal-to-noise ratio for CAP was obtained compared to more classical 5 microm particulate HPLC columns. The proposed analytical methodology includes an enzymatic digestion, which liberates glucuronide-bound CAP from kidney tissue. The extracts obtained after an Extrelut clean-up are sufficiently pure to permit routine injection of biological samples into the sub-2 microm particulate HPLC column, without observing rapid deterioration of peak shape or column clogging problems. The time for one chromatographic run was 4.2 min. The described method was validated for two particularly difficult matrices (kidney and honey). Decision limits (CC alpha) were 0.007 microg/kg (honey) und 0.011 microg/kg (kidney), which are significantly below the current MRPL.     

Determination of coumaphos, chlorpyrifos and ethion residues in propolis tinctures by matrix solid-phase dispersion and gas chromatography coupled to flame photometric and mass spectrometric detection

A new analytical method has been developed and successfully evaluated in routine application for the quantitative analysis of a selected group of organophosphate pesticides (coumaphos, chlorpyrifos and ethion) which can be found at trace levels in propolis tinctures (ethanolic propolis extracts); a valuable commodity used as raw material in the food and pharmaceutical industries for which there have been few attempts for pesticide residue analysis reported in the literature. The proposed methodology is based on matrix solid phase dispersion (MSPD) using aluminum sulfate anh. a novel dispersant material and subsequent column chromatography clean-up in silica gel prior to gas chromatography (GC) with both flame photometric detector (FPD) and mass spectrometry (MS) detection used for the routine quantification and identification of the residues, respectively. The limits of detection, for coumaphos, chlorpyrifos and ethion were below 26.0 μg/kg in FPD and 1.43 μg/kg for MS detection. Mean recoveries were in the range of 85-123% with RSD values below 13%, which suggests that the proposed method is fit for the purpose of analyzing pesticides in propolis tinctures containing high concentration of polyphenolics. The method has been successfully applied in our laboratory for the last 2 year in the analysis of real propolis tinctures samples.     

气相色谱-质谱联用法测定动物组织中氯霉素、氟甲砜霉素和甲砜霉素的残留量

建立了气相色谱-负离子化学电离源质谱同时测定动物组织中氯霉素(CAP)、甲砜霉素(TAP)和氟甲砜霉素(FF)残留量的方法。样品用乙酸乙酯提取,正己烷分配去脂肪,再用Florisil柱进一步净化,甲苯作为反应介质,用N,O-双(三甲基硅基)三氟乙酰胺(BSTFA)-三甲基氯硅烷(TMCS)(体积比为99∶1)进行硅烷化处理,用间硝基氯霉素(m-CAP)作为内标进行测定。CAP的检测限可达到0.03 μg/kg,TAP和FF的检测限可达到0.2 μg/kg;上述3种药物的标准曲线的线性相关系数均大于0.99。CAP,FF和TAP的批内测定的精密度(以相对标准偏差表示)依次为5.5%,10.4%和8.8%;批间测定的精密度依次为7.4%,20.7%和19.1%。回收率为80.0%~111.5%,相对标准偏差为1.2%~15.4%。该方法前处理步骤简单,处理后杂质干扰少,灵敏度高,适用性强,可用于猪肉及禽类、水产品等多种动物组织中氯霉素类药物残留的检测。     

Determination of phosmet and its metabolites in olives by matrix solid-phase dispersion and gas chromatography-mass spectrometry

An accurate method based on matrix solid-phase dispersion (MSPD), and gas chromatography-mass spectrometry (GC/MS) was developed for determination of phosmet residues and its metabolites (phosmet-oxon, phthalimide, N-hydroxymethylphthalimide, and phthalic acid) in olive fruits. After testing different sorbents and eluents for MSPD extraction, C₁₈ and acetonitrile were found to be the most appropriate for clean-up of the samples, in terms of yields and efficient removal of interfering compounds. All analytes were determined in selective ion monitoring (SIM) mode following a derivatization step with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) containing 1% of trimethylchlorosilane (TMCS), except for phosmet and phosmet-oxon which were analyzed directly. The method showed suitable linearity (correlation coefficients higher than 0.8919 for all the compounds) and suitable sensitivity (limit of detection lower than 0.06 mg/kg). It was successfully applied in the analysis of olive fruits collected during the preharvest interval and olive oil. Phosmet residues found in all samples were lower than the maximum residue limits established by legislation (2 mg/kg).     

Quantitative determination of four nitrofuran metabolites in meat by isotope dilution liquid chromatography-electrospray ionisation-tandem mass spectrometry

A confirmatory method based on isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the low-level determination of residues of four nitrofuran veterinary drugs in meat, e.g., furazolidone, furaltadone, nitrofurantoin, and nitrofurazone. The procedure entails an acid-catalysed release of protein-bound metabolites, followed by their in situ conversion into the 2-nitrobenzaldehyde (NBA) imine-type derivatives. Liquid-liquid extraction and clean-up on a polymeric solid phase extraction cartridge are then performed before LC-MS/MS analysis by positive electrospray ionisation (ESI) applying multiple reaction monitoring of three transition reactions for each compound. Reliable quantitation is obtained by using one deuterated analogue per analyte (d4-NBA derivative) as internal standard (IS). Validation of the method in chicken meat was conducted following the European Union (EU) criteria for the analysis of veterinary drug residues in foods. The decision limits (CCalpha) were 0.11-0.21 microg/kg, and the detection capabilities (CCbeta) 0.19-0.36 microg/kg, thus below the minimum required performance limit (MRPL) set at 1 microg/kg by the EU. The method is robust and suitable for routine quality control operations, and more than 200 sample injections were performed without excessive pollution of the mass spectrometer or loss of LC column performance.     

高效液相色谱-串联质谱法测定动物组织中的16种喹诺酮类药物残留

建立了动物组织样品中萘啶酸、恶喹酸、氟甲喹、诺氟沙星、依诺沙星、环丙沙星、洛美沙星、丹诺沙星、恩诺沙星、氧氟沙星、沙拉沙星、二氟沙星、麻保沙星、培氟沙星、司帕沙星、奥比沙星等16种喹诺酮类兽药多残留量的高效液相色谱-串联质谱测定方法。用酸性乙腈萃取样品中的16种喹诺酮类药物残留,然后用正己烷脱脂,旋转蒸发浓缩,以Inertsil C8-3色谱柱分离,在正离子模式下以电喷雾电离串联质谱进行测定。在10,50,100 μg/kg 3个加标水平下进行了验证试验,方法的线性范围为10~100 μg/kg,平均回收率为62.4%~102%,相对标准偏差为1.4%~11.9%。该方法简便、快速、准确,各项技术指标满足国内外法规的要求,可用于鸡肉、鸡肝和鱼肉等动物组织样品中喹诺酮类药物多残留的确证检测。     

A quantitative method for the detection of sulfonamide residues in meat and milk samples with a high-performance thin-layer chromatographic method.

Sulfonamides are widely used in veterinary medicine for prophylactic purposes and for the treatment of various infections of food-producing animals. This means that residues of these drugs and their possible metabolites may occur in food of animal origin. In Belgium, a zero tolerance level for sulfonamides in edible animal tissues has been set. In order to check this zero level on a routine basis, a rapid and sensitive method has to be available. For this purpose, a quantitative high-performance thin-layer chromatographic (HPTLC) method for the detection of sulfonamide residues in animal tissue and milk samples has been developed. The sample preparation consists of a liquid extraction followed by a solid phase extraction (SPE) on disposable columns for the meat samples and a matrix solid phase dispersion (MSPD) for the milk samples. A three-multiple development chromatographic system is used for the separation and a derivatization with fluorescamine decreases the minimal detectable quantity per spot from 1.42 to 0.32 ng. The limit of quantification is 4 micrograms/kg for milk and meat samples.     

Multiresidue method for simultaneous determination of ten quinolone antibacterial residues in multimatrix/multispecies animal tissues by liquid chromatography with fluorescence detection: single laboratory validation study

Quinolone antibacterials are veterinary drugs authorized for use in food animal production. The analysis of residual amounts of drugs in food from animal origin is important for quality control of products for consumers. For this purpose, Maximum Residue Limits (MRLs) have been set up by a European Union Council Regulation on Veterinary Drug Residues (No. 90/2377/EEC and subsequent), and 8 quinolones received MRLs at concentration levels depending on both the matrix and the animal species of interest. A method was developed for screening and confirming 10 quinolone residues (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, oxolinic acid, sarafloxacin) in a wide variety of matrixes of different animal species. It involves extraction of the residues from the biological tissues/fluids by acidic aqueous solution, centrifugation and filtration prior to injection on a C18 narrow-bore column, and detection through a 3-step-mode fluorescence detector. The method was validated during a 2-week study for a set of 8 species-matrixes (i.e., bovine raw milk, bovine muscle, porcine muscle, porcine kidney, porcine liver, fish flesh and skin, poultry muscle, whole egg). Residues were quantified down to 15 microg/kg with limits of detection and quantitation ranging from 4 to 11 and 13 to 36 microg/kg, respectively, which are sufficient compared to the wide range of MRLs set for these substances (from 30 microg/kg for danofloxacin in milk to 1900 microg/kg for difloxacin in poultry liver). The limit of performance of the method in terms of CCalpha and CCbeta, the critical concentrations stated in the Decision No. 2002/657/EC and the ISO Standard No. 11843, has been calculated for the authorized (MRL) substances but only estimated in the case of the nonauthorized (non-MRL) substances.     

Determination of multiclass pesticides in river sediments via matrix solid-phase dispersion extraction and gas chromatography–tandem mass spectrometry

A fast and environment-friendly analytical method was implemented to determine multiclass pesticides in river sediments. Twenty-three pesticides—organochlorine pesticides, organophosphorus pesticides, and triazines—were extracted via matrix solid-phase dispersion (MSPD) and analyzed by gas chromatography–tandem mass spectrometry (GC–MS/MS). Florisil demonstrated excellent analytes uptake capability as the extractant phase, with suitable selectivity for treating complex sediment samples. Under defined extraction conditions, the MSPD–GC–MS/MS method demonstrated robustness in the n inter-day analysis of sediments from different sources, providing limit of quantifications (LOQs) between 5 and 15 ng/g, linear responses in the range between LOQs and 150 ng/g, extraction recoveries of 71%–106%, and precision, assessed as relative standard deviation below 20%. The MSPD significantly reduced samples and solvents’ consumption, providing critical environmental gains compared to traditional extraction methods like Soxhlet. Finally, the method was applied to analyze sediment samples from three different collection areas of the Subachoque River (Cundinamarca, Colombia), demonstrating a fast, efficient, confident, and profitable analytical tool for pollution control and monitoring in environmental samples. The method allowed us to determine the current use in Colombia of banned pesticides under the 2001 Stockholm Convention.     

Fast gas chromatography with solid phase extraction clean-up for ultratrace analysis of pesticide residues in baby food

A sample preparation method based on single solvent phase extraction and solid-phase extraction (SPE-NH2) clean-up is studied in combination with fast capillary gas chromatography (GC) to determine 18 selected pesticides belonging to various chemical classes in apples, the common raw material for baby food production and baby food, at the concentration level < or = 10 microg/kg maximum residual limit (MRL). Possibilities of mass spectrometry (MS) detector and electron capture detector (ECD) in fast gas chromatography (GC) of samples with complex matrice at ultra trace levels of pesticide residues were studied and compared. MS detection in single ion monitoring (SIM) mode provided higher selectivity compared to ECD. Optimisation of extraction as well as the simplifying of the whole process of sample preparation was carried out. Recoveries obtained at concentration level of 5 microg/kg (the required value for limit of quantification (LOQ) in baby food) were >90%, except of dimethoate (77.7%) and captan (46.4%) with MS detection. The obtained LOQs were at least 1 order lower than 5 microg/kg for the majority of compounds. The repeatability of gas chromatography-mass spectrometry (GC-MS) measurements of the matrix matched standards expressed as relative standard deviation was <11% except of captan and cypermethrin.