Determination,residue and risk assessment of trifloxystrobin,trifloxystrobin acid and tebuconazole in Chinese rice consumption

A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R² > 0.99), accuracy (average recoveries of 74.3–108.5%) and precision (intra- and inter-day relative standard deviations of 0.9–8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7–8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 μg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice.     

Simultaneous determination of difenoconazole,trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon under field conditions by GC–MS/MS

An optimized quick, easy, cheap, effective, rugged and safe method for the simultaneous determination of difenoconazole, trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon and soil was developed and validated by gas chromatography with tandem mass spectrometry. The samples were extracted with acetonitrile (1% formic acid) and cleaned up by dispersive solid‐phase extraction with octadecylsilane sorbent. The limit of quantification of the method was 0.01 mg/kg, and the limit of detection was 0.003 mg/kg for all three analytes. The recoveries of the fungicides in watermelon, pulp and soil were 72.32–99.20% for difenoconazole, 74.68–87.72% for trifloxystrobin and 78.59–92.66% for trifloxystrobin acid with relative standard deviations of 1.34–14.04%. The dissipation dynamics of difenoconazole and trifloxystrobin in watermelon and soil followed the first‐order kinetics with half‐lives of 3.2–8.8 days in both locations. The final residue levels of difenoconazole and trifloxystrobin were below 0.1 mg/kg (maximum residue level [MRL] set by China) and 0.2 mg/kg (MRL set by European Union), respectively, in pulp samples collected 14 days after the last application. These results could help Chinese authorities to establish MRL of trifloxystrobin in watermelon and provide guidance for the safe and proper application of both fungicides on watermelon.     

Simultaneous determination of tebuconazole,trifloxystrobin, and its metabolite trifloxystrobin acid residues in gherkin under field conditions

A rapid, simple, and selective analytical method for the simultaneous determination of tebuconazole, trifloxystrobin, and its metabolite trifloxystrobin acid residues in gherkin and soil was developed and validated by gas chromatography coupled with mass spectrometry. The samples were extracted with acetonitrile and cleaned up by dispersive solid‐phase extraction with primary secondary amine sorbent. The limit of quantification of the method was 0.05 mg/kg for all three compounds. The method was validated using blank samples spiked at three levels and recoveries ranged from 83.5 to 103.8% with a relative standard deviation of 1.2 to 4.8%. The developed method was validated and applied for the analysis of a degradation study sample. The residues of trifloxystrobin and tebuconazole were found to dissipate following first‐order kinetics with half‐life ranging between 3.31–3.38 and 3.0–3.04 days, respectively, for two different dosages. Pesticide residues were below the European Union maximum residue level after seven days for trifloxystrobin (0.2 mg/kg) and ten days for tebuconazole (0.05 mg/kg), which suggested the use of this fungicide mixture to be safe to humans. These results can be utilized in formulating the spray schedule and safety evaluation on trifloxystrobin and tebuconazole in gherkin crop.     

Simultaneous and rapid determination of deoxynivalenol and its acetylate derivatives in wheat flour and rice by ultra high performance liquid chromatography with photo diode array detection

A simple and reliable method of ultra high performance liquid chromatography coupled with photo‐diode array detection has been proposed for the simultaneous determination of deoxynivalenol and its acetylated derivatives in wheat flour and rice, especially focusing on the optimization of sample extraction, cleanup, and chromatographic separation conditions. Sample pretreatment consisted of a first step using a quick, easy, cheap, effective, rugged, and safe based extraction procedure and a subsequent cleanup step based on solid‐phase extraction. The method was extensively validated in wheat flour and rice, obtaining satisfactory analytical performance with good linearity (R² ≥ 0.999), acceptable recoveries (80.0–104.4%), and repeatability (RSDs 1.3–10.7%). The limits of detection (21.7–57.4 μg/kg) and quantitation (72.3–191.4 μg/kg) for deoxynivalenols were lower than those usually permitted by various countries’ legislation in these food matrices. The method was applied to 34 wheat and rice samples. The results were further compared with results of ultra high performance liquid chromatography with electrospray ionization tandem mass spectrometry.     

Simultaneous determination of flupyradifurone and its two metabolites in fruits,vegetables, and grains by a modified quick,easy, cheap,effective, rugged,and safe method using ultra high performance liquid chromatography with tandem mass spectrometry

An effective analytical method for the simultaneous determination of a novel insecticide flupyradifurone and its two metabolites was developed using ultra high performance liquid chromatography with tandem mass spectrometry coupled with a quick, easy, cheap, effective, rugged, and safe procedure. The three target compounds were extracted with acetonitrile and cleaned up with octadecylsilane, and were separated successfully between 1.9 and 3.1 min using an HSS T3 chromatographic column connected to an electrospray ionization source. All the matrix‐matched samples at three fortified levels (0.01, 0.05, and 0.5 mg/kg) provided satisfactory recoveries in the range of 70.3–116.5% with relative standard deviations below 18.6%. The limits of quantitation were 10 μg/kg for flupyradifurone and difluoroethylamino‐furanone and 100 μg/kg for 6‐chloronicotinic acid. The limit of quantification of flupyradifurone was far below the maximum residue limit in the USA. The method is of great significance for establishing maximum residue limits in China.     

A quick,easy, cheap,effective, rugged,and safe method for the simultaneous detection of four triazolone herbicides in cereals combined with ultrahigh performance liquid chromatography with tandem mass spectrometry

This paper describes a novel, rapid, and sensitive analytical method for monitoring four triazolone herbicides in cereals (wheat, rice, corn, and soybean), using a quick, easy, cheap, effective, rugged, and safe sample extraction procedure followed by ultrahigh performance liquid chromatography coupled with tandem mass spectrometry. The four triazolone herbicides (amicarbazone, carfentrazone‐ethyl, sulfentrazone, and thiencarbazone‐methyl) were extracted using acidified acetonitrile (containing 1% v/v formic acid) and subsequently purified with octadecylsilane (C₁₈) prior to sample analysis. Ultrahigh performance liquid chromatography coupled with tandem mass spectrometry was operated in positive and negative ionization switching mode. Amicarbazone and carfentrazone‐ethyl were detected in the positive mode (ESI+), while sulfentrazone and thiencarbazone‐methyl were detected in the negative mode (ESI?). All compounds were successfully separated in less than 3.0 min. Further optimization achieved desired recoveries ranging from 74.5 to 102.1% for all analytes with relative standard deviation values ≤17.2% in all tested matrices at three levels (10, 100, and 500 μg/kg). The limits of detection for all compounds were ≤2.3 μg/kg, and the limits of quantitation did not exceed 7.1 μg/kg. The developed method showed excellent linearity (R² ≥ 0.994) and was proven to be highly efficient and reliable for the routine monitoring of triazolone herbicides in cereals.     

Simultaneous determination of malachite green, crystal violet, methylene blue and the metabolite residues in aquatic products by ultra-performance liquid chromatography with electrospray ionization tandem mass spectrometry

This work describes solid-phase extraction-ultra-performance liquid chromatography with electrospray ionization tandem spectrometry for determination of malachite green and metabolite leucomalachite green, crystal violet and metabolite leucocrystal violet, methylene blue and metabolites including azure A, azure B and azure C in aquatic products. Samples were extracted with acetonitrile and ammonium acetate buffer and purified by liquid extraction with dichloromethane, and then on MCAX solid-phase extraction cartridges. Then the extract was evaporated at 45°C by nitrogen blow. The residue was dissolved and separated by an Acquity BEH C18 column. The mobile phase was acetonitrile (A) and 5 mmol/L of ammonium acetate containing 0.1% formic acid (B). Analytes were confirmed and quantified using a tandem mass spectrometry system in multiple reaction mode with triple quadrupole analyzer using positive polarity mode. The limits of detection of malachite green, leucomalachite green, crystal violet and leucocrystal violet were 0.15 μg/kg, the limits of quantification were 0.50 μg/kg, and the average recoveries were more than 75% with spiked residues from 0.5 to 10 μg/kg. The relative standard deviations were less than 13%. The limits of detection of methylene blue, azure A, azure B and azure C were 0.3 μg/kg, the limits of quantification were 1.0 μg/kg, the average recoveries were more than 70% with spiked residues from 1.0 to 10 μg/kg and the relative standard deviations were less than 15%. The method has the merits of simplicity, sensitivity and rapidity, and can be used for simultaneous determination of the analytes in aquatic products.     

Simultaneous determination of five strobilurin fungicides and the metabolite BF-500-3 in cereals,fruits and vegetables

A rapid and sensitive method for the simultaneous determination of five strobilurin fungicides and the metabolite BF-500-3 in cereals (maize and wheat), fruits (grape and apple) and vegetables (cucumber and tomato) was developed by a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method using high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS). The five strobilurin fungicides (kresoxim-methyl, picoxystrobin, pyraclostrobin, azoxystrobin and trifloxystrobin) and the metabolite BF-500-3 were extracted from six matrices using acetonitrile and subsequently cleaned up by dispersive solid phase extraction (d-SPE) using octadecylsilane (C₁₈) as sorbent prior to HPLC-MS/MS analysis. The determination of the six compounds was achieved in less than 6.0 min using an electrospray ionisation source in positive mode (ESI+). This method showed the linearity with the coefficients of determination (R²) higher than 0.9929. The limits of quantification (LOQs), defined as the lowest spiking level, were 5 μg/kg for all the fungicides in all matrices. Recovery studies were performed at three fortification levels (5, 10 and 100 μg/kg) and the overall average recoveries ranged from 76.9% to 114.2% with the relative standard deviation (RSD) less than 13.6% for all the analytes. The method is demonstrated to be convenient and reliable for the routine monitoring of five strobilurin fungicides and the metabolite BF-500-3 in cereals, fruits and vegetables.     

Determination of tebuconazole, trifloxystrobin and its metabolite in fruit and vegetables by a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method using gas chromatography with a nitrogen-phosphorus detector and ion trap mass spectrometry

A new analytical method using QuEChERS procedure by gas chromatography with a nitrogen-phosphorus detector (GC-NPD) and ion trap mass spectrometry (GC-IT-MS) for the quantitative determination of tebuconazole, trifloxystrobin and its metabolite trifloxystrobin acid has been developed and validated. The analytes were extracted from five fruit and vegetable matrices using acetonitrile and subsequently cleaned up using primary secondary amine (PSA) or octadecylsilane (C18) as sorbent prior to GC analysis. The present methods provided sufficient sensitivity as reflected by the values of limit of detection (LOD) and limit of quantification (LOQ) of 0.4-7 and 1.2-20 μg/kg for GC-IT-MS/MS and GC-NPD. The recoveries were, on average, 68-117 and 68-121%, respectively, for three compounds by GC-NPD and GC-IT-MS/MS with intra-day precision achieved with an RSD of 2.7-19.1%. The inter-day precision was better than 15.1% as determined by GC-NPD. The QuEChERS procedure, by using two sorbents (PSA and C18) and the matrix-matched standards, gave satisfactory recoveries and RSD values in different matrices. IT-MS acquisition provided higher specificity and selectivity for pesticides and better limit of detection and quantification. However, the repeatability and precision of NPD method were better compared with IT-MS.     

Determination of 19 sulfonamides residues in pork samples by combining QuEChERS with dispersive liquid–liquid microextraction followed by UHPLC–MS/MS

A new simple and rapid pretreatment method for simultaneous determination of 19 sulfonamides in pork samples was developed through combining the QuEChERS method with dispersive liquid–liquid microextraction followed by ultra‐high performance liquid chromatography with tandem mass spectrometry. The sample preparation involves extraction/partitioning with QuEChERS method followed by dispersive liquid–liquid microextraction using tetrachloroethane as extractive solvent and the acetonitrile extract as dispersive solvent that obtained by QuEChERS. The enriched tetrachloroethane organic phase by dispersive liquid–liquid microextraction was evaporated, reconstituted with 100 μL acetonitrile/water (1:9 v/v) and injected into an ultra‐high performance liquid chromatography with a mobile phase composed of acetonitrile and 0.1% v/v formic acid under gradient elution and separated using a BHE C₁₈ column. Various parameters affecting the extraction efficiency were investigated. Matrix‐matched calibration curves were established. Good linear relationships were obtained for all analytes in a range of 2.0–100 μg/kg and the limits of detection were 0.04–0.49 μg/kg. Average recoveries at three spiking levels were in the range of 78.3–106.1% with relative standard deviations less than 12.7% (n = 6). The developed method was successfully applied to determine sulfonamide residues in pork samples.     

Rapid residue analysis of oxathiapiprolin and its metabolites in typical Chinese soil,water, and sediments by a modified quick,easy, cheap,effective, rugged,and safe method with ultra high performance liquid chromatography and tandem mass spectrometry

A sensitive and effective method for the simultaneous determination of residues from a new fungicide, oxathiapiprolin, and its metabolites (IN‐E8S72 and IN‐WR791) in soil, water, and sediment, was developed using ultra high performance liquid chromatography with tandem mass spectrometry. Three compounds were extracted from water, soil, and sediment by using acetonitrile and different proportions of formic acid aqueous solution (1% v/v for water; 2% v/v for soil; and sediment), and were cleaned with octadecylsilane. The target compounds were determined within 5 min using an electrospray ionization source in the positive mode for oxathiapiprolin and in the negative mode for the two metabolites. The limits of quantification for all the three compounds were 0.1 μg/kg in water and 1 μg/kg in soil and sediment. Recovery studies were performed using three spiked levels (0.1, 1, and 10 μg/kg for water; 1, 10, and 50 μg/kg for soil and sediment). The overall average recoveries ranged from 64.8 to 112.7% with all intra‐ and interday relative standard deviation values below 19.4 and 19.1%, respectively. The method validation confirmed that the proposed method was convenient and reliable for determining residual oxathiapiprolin and its metabolites in soil, water, and sediments.     

超高效液相色谱-串联质谱法同时测定鸡肝中残留的四环素类、磺胺类和喹诺酮类药物

采用超高效液相色谱-串联质谱(UPLC-MS/MS)在正离子模式下通过多反应监测(MRM)方式同时测定了鸡肝脏组织中3种四环素类药物、10种磺胺类药物以及8种喹诺酮类药物的残留。试样由McIlvaine缓冲液-乙腈(体积比为1:4)、乙腈提取,合并上清液并用氮气吹干,用0.05 mol/L磷酸三乙胺缓冲液-乙腈(体积比为85:15)溶解残余物,经正己烷脱脂后,采用UPLC-MS/MS进行定性、定量分析。该方法对测定的21种药物的检出限均为2 μg/kg,定量限均为5 μg/kg。在添加水平分别为5,10和50 μg/kg时,21种药物的加标回收率为66.8%～128.5%,日内测定的相对标准偏差(RSD)为0.8%～20.2%,日间测定的RSD为2.2%～15.3%。该方法可作为动物源性食品中这3类药物残留检测的确证方法。     

Evaluation of a new modified QuEChERS method for the monitoring of carbamate residues in high‐fat cheeses by using UHPLC–MS/MS

A simple and efficient method for the determination of 28 carbamates in high‐fat cheeses is proposed. The methodology is based on a modified quick, easy, cheap, effective, rugged, and safe procedure as sample treatment using a new sorbent (Z‐Sep⁺) followed by ultra‐high performance liquid chromatography with tandem mass spectrometry determination. The method has been validated in different kinds of cheese (Gorgonzola, Roquefort, and Camembert), achieving recoveries of 70–115%, relative standard deviations lower than 13% and limits of quantification lower than 5.4 μg/kg, below the maximum residue levels tolerated for these compounds by the European legislation. The matrix effect was lower than ±30% for all the studied pesticides. The combination of ultra‐high performance liquid chromatography and tandem mass spectrometry with this modified quick, easy, cheap, effective, rugged, and safe procedure using Z‐Sep⁺ allowed a high sample throughput and an efficient cleaning of extracts for the control of these residues in cheeses with a high fat content.     

液相色谱-串联质谱法快速筛查测定浓缩果蔬汁中的156种农药残留

建立了浓缩果蔬汁中156种农药多残留的液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)测定方法。样品用1%醋酸乙腈溶液萃取,经Waters Sep-Pak Vac固相萃取柱净化,乙腈-甲苯(体积比为3∶1)洗脱,旋转蒸发浓缩,用乙腈-水（体积比为3∶2）溶解,以Agilent ZORBAX SB-C18色谱柱分离,以电喷雾电离串联质谱在正离子多反应监测(MRM)模式下进行测定。对156种农药在5种浓缩果蔬汁(橙汁、苹果汁、葡萄汁、白菜汁、胡萝卜汁)中两个添加水平下的回收率进行了测定,回收率范围为57.2%～122.7%,相对标准偏差范围为0.9%～19.8%。方法的检出限(S/N=3)和定量限(S/N=10)范围分别为0.10～56.77 μg/kg和0.33～189.23 μg/kg。该方法样品前处理简单、快速、分析时间短,灵敏度、准确度和精密度均符合农药多残留检测技术的要求,适用于苹果汁、橙汁、葡萄汁、白菜汁、胡萝卜汁等浓缩果蔬汁中156种农药多残留的快速筛查测定。     

超高效液相色谱-电喷雾串联质谱法同时分析鸡肉中7种氟喹诺酮类药物残留

建立了一种同时测定鸡肉中7种氟喹诺酮类药物残留的超高效液相色谱-电喷雾串联质谱确证分析方法(UPLC-ESI-MS/MS)。样品经酸化乙腈提取、正己烷脱脂和HLB固相萃取柱净化,采用ACQUITY UPLCTM BEH C18色谱柱(50 mm×2.1 mm,1.7 μm)分离,以0.1%甲酸水溶液和乙腈作为流动相进行梯度洗脱,电喷雾质谱检测,正离子多反应监测模式进行定性和定量分析。7种药物在5～100 μg/kg范围内线性关系良好,相关系数(r2)均大于0.99;以5,25,50 μg/kg3个浓度水平进行添加回收试验,7种药物的平均回收率在79.2%～108.6%之间,相对标准偏差为4.2%～8.9%,方法的检出限(LOD)为0.2～1.4 μg/kg。方法重现性好、灵敏度高、分析时间短、确证能力强,适用于鸡肉中氟喹诺酮类药物多残留的确证检测。     

Comparison of pulse glow discharge‐ion mobility spectrometry and liquid chromatography with tandem mass spectrometry based on multiplug filtration cleanup for the analysis of tricaine mesylate residues in fish and water

Analytical methods based on multiplug filtration cleanup coupled with pulse glow discharge‐ion mobility spectrometry and liquid chromatography tandem mass spectrometry were developed for the analysis of tricaine mesylate residue in fish and fish‐raising water samples. A silica fiber holder and an appropriate new interface were designed to make the direct introduction of the fiber into the pulse glow discharge‐ion mobility spectrometry introduction mechanism. The multiplug filtration cleanup method with adsorption mixtures was optimized for the determination of tricaine mesylate in fish samples. Good linear relationships were obtained by the two methods. For fish samples, limits of detection were 6 and 0.6 μg/kg by ion mobility spectrometry and liquid chromatography with tandem mass spectrometry, respectively. The matrix effect of the established liquid chromatography tandem mass spectrometry method was negligible for fish samples but that of the ion mobility spectrometry method was not. The two methods were compared. The ion mobility spectrometry system could be used a rapid screening tool on site with the advantage of rapidity, simplicity, and portability, and the liquid chromatography tandem mass spectrometry system could be used for validation in laboratory conditions with the advantage of lower limit of detection, stability, and precision.     

Multiresidue method for the simultaneous determination of 16 acaricides by modified quick,easy, cheap,effective, rugged,and safe extraction and ultra‐high performance liquid chromatography coupled with tandem mass spectrometry in citrus

An ultra‐high performance liquid chromatography coupled with tandem mass spectrometry analytical method was developed for simultaneously determining 16 acaricides in citrus based on an optimized quick, easy, cheap, effective, rugged, safe strategy. Good linearities of the standard curve of 5–1000 μg/kg was obtained with regression coefficients higher than 0.9967. Recoveries for all compounds ranged from 72 to 111% with relative standard deviations lower than 14.4% at spiked levels of 5, 50, and 500 μg/kg. Low limits of detection and quantification were readily achieved ranging from 0.05 to 2.7 and 0.10 to 4.3 μg/kg, respectively. Matrix effects were also evaluated for 16 targets with most compounds achieved signal enhancement. Citrus peel gave the highest extent matrix effects, followed by whole citrus and pulp. Finally, this method was successfully applied to detect acaricides residues in real citrus samples. The results showed that pyridaben and quinalphos were the two most frequent and high‐concentration compounds with concentrations exceeding the maximum residue limits in five samples, suggesting that the use of these acaricides should be regulated in China in the future.     

UPLC-MS/MS测定葡萄籽提取物中78种农药残留

建立了超高效液相色谱串联质谱法(UPLC-MS/MS)检测葡萄籽提取物中78种农药残留物的分析方法。样品用乙腈振荡提取,经乙二胺-N-丙基甲硅烷(PSA)和石墨化炭(GCB)固相萃取柱串联净化,乙腈-甲苯(V/V3:1)洗脱,洗脱液浓缩至约0.5 mL后,于45℃下氮气吹干,1.0 mL乙腈定容,UPLC-MS/MS测定,外标法定量。葡萄籽提取物中,78种农药在0.001～0.2μg/mL范围内线性关系均良好;所有农药的方法定量限(LOQ)均低于17.0μg/kg;在5,25,50μg/kg的添加水平下,葡萄籽提取物中78种农药的平均回收率处于72.6%～113.5%之间,相对标准偏差不大于11%。方法适用于葡萄籽提取物中78种农药残留的快速筛查测定。     

Enantioselective determination of acaricide etoxazole in orange pulp,peel, and whole orange by chiral liquid chromatography with tandem mass spectrometry

An efficient enantioselective method for the determination of etoxazole in orange pulp, peel, and whole orange was developed using liquid chromatography with tandem mass spectrometry. The enantioseparation was performed on a Chiralpak AD‐3R column at 30ºC using acetonitrile with 0.1% formic acid solution (80:20, v/v) as the mobile phase in less than 5 min. Quantification was achieved using matrix‐matched standard calibration curves. The overall mean recoveries for two enantiomers from orange pulp and whole orange were 91.0–99.6% and the orange peel was 92.6–103.1%, with relative standard deviations of 0.8–5.4% intraday and 2.0–4.8% interday at 1, 10, and 100 μg/kg levels, and 1.3–5.2% intraday and 3.5–4.3% interday at 5, 50, and 500 μg/kg levels, respectively. The limits of quantification for all enantiomers in three matrices did not exceed 5 μg/kg. Moreover, the absolute configuration of etoxazole enantiomers had been determined by the combination of experimental and predicted electronic circular dichroism spectra, and the first eluted enantiomer was confirmed as (S)‐etoxazole on a Chiralpak AD‐3R column while (R)‐etoxazole was first on three cellulose chiral columns. The application of the proposed method to real sample analysis suggests its potential use in enantioselective determination of etoxazole enantiomers in citrus.     

QuEChERS-based extraction procedure for multifamily analysis of phytohormones in vegetables by UHPLC-MS/MS

A new method has been developed and validated for the simultaneous analysis of different phytohormones (auxins, cytokinins and gibberellins) in vegetables. The compounds were extracted using a QuEChERS-based method (acronym of quick, easy, cheap, effective, rugged and safe). The separation and determination of the selected phytohormones were carried out by ultra high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), using electrospray ionization source (ESI) in positive and negative ion modes. The method was validated and mean recoveries were evaluated at three concentration levels (50, 100 and 250 μg/kg), ranging from 75 to 110% at the three levels assayed. Intra- and interday precisions, expressed as relative standard deviations (RSDs), were lower than 20 and 25%, respectively. Limits of quantification (LOQs) were equal or lower than 10 μg/kg. The developed procedure was applied to seven courgette samples, and naphthylacetic acid, naphthylacetamide and benzyladenine were found in some of the analysed samples.