Two-step Clean-up Research Articles

Comparison of high resolution mrm and sequential window acquisition of all theoretical fragment-ion acquisition modes for the quantitation of 48 wastewater-borne pollutants in lettuce

Screening of a large number of chemicals of emerging concern is highly desirable for the control of crops irrigated with reclaimed water since it is considered an alternative water source of great value. This study describes a high resolution mass spectrometry approach for developing methods for quantification in lettuce leaves of 48 different wastewater-borne pollutants (including analgesics and anti-inflammatories, anti-hypertensives, antifungal agents, lipid regulators, psychiatric drugs and stimulants, β-blockers, antibiotics, antimycotics, and sweeteners) frequently found in water resources. In this respect, a simple and fast QuEChERS-based method for the determination of contaminants in lettuce has been developed. During extraction, the use of formic acid was adopted to further improve the results of some problematic compounds (e.g., fenofibrate, furosemide, metronidazole, oxcarbazepine, sulfanilamide). High resolution multiple reaction monitoring (MRMHR) and SWATH acquisition were compared in term of accuracy, repeatability, sensitivity, linearity and matrix effect. Both methods provided similar recoveries between 80 and 120% in lettuce leaves, although sulfanilamide, ciprofloxacin, and sulfamethazine presenting values of 26.8, 27.8, and 28.4% in MRMHR and 25, 33.9, and 35% in SWATH, respectively. The effectiveness of a two-step cleanup on analyte recovery was also assessed and matrix effects were also taken into consideration during the method validation. The developed method allows the simultaneous quantitative analysis of 48 compounds (drug residues and metabolites) in lettuce leaves irrigated with treated wastewater for human consumption. Application of the present method to lettuce crops growth in controlled conditions showed the presence of 14 out 48 studied compounds with similar concentrations in both acquisition modes ranging from 3.3 and 1.3 ng g − 1 for climbazole (for MRMHR and SWATH, respectively) to 33.2 and 17.7 ng g − 1 for sulfamethazine. Drug residues such as carbamazepine (6.0 and 8.5 ng g − 1), and its metabolite carbamazepine epoxide (18.1 and 16.5 ng g − 1), frequently found in wastewater effluents, were also detected.

Modified QuEChERS extraction for the analysis of young-of-year smallmouth bass using GC × GC-TOFMS.

Signs of disease, such as external lesions, have been prevalent in smallmouth bass throughout the Susquehanna River Basin, USA. Previous targeted chemical studies in this system have identified known persistent organic pollutants, but a common explanatory link across multiple affected sites remains undetermined. A fast and robust extraction method that can be applied to young-of-year fish is needed to effectively screen for target and non-target compounds that may be impacting organism health. The quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction methodology was optimized to perform both targeted and non-targeted chemical analyses from a single extraction of whole young-of-year fish. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) was used for extract analysis. Sample extraction was performed using the solvent ethyl acetate, followed by a two-step cleanup in which samples were frozen for lipid removal and subjected to dispersive solid phase extraction using Florisil. A sample of 21 young-of-year smallmouth bass collected from areas with disease and exhibiting different types of external lesions were evaluated for 233 target compounds. A total of 34 organic contaminants, including polychlorinated biphenyls, brominated diphenyl ethers, organochlorinated pesticides, and personal care products, were detected. Data from this sample set was then analyzed for non-targets. Using the Fisher ratio method and multivariate analysis, an additional 10 significant features were identified specific to either fish with visible lesions or with no visible disease characteristics.

Single sample preparation for brominated flame retardants in fish and shellfish with dual detection: GC-MS/MS (PBDEs) and LC-MS/MS (HBCDs).

An analytical method for the simultaneous determination of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in fish, shellfish and muscle of terrestrial animals was developed as an extension of a previously validated method for PBDE analysis. A single sample preparation based on QuEChERS-like extraction and a two-step clean-up, followed by a dual instrumental detection, was implemented. GC-MS/MS was used for PBDEs and LC-MS/MS for HBCDs. The method allows the quantification of fifteen PBDEs (28, 47, 49, 66, 77, 85, 99, 100, 138, 153, 154, 183, 197, 206, 209) and three HBCD isomers (α, β and γ), reaching 10 pg/g LOQs for all the analytes except BDE 206 and 209 (100 pg/g LOQ). The validated method was applied to the analysis of 12 fish and shellfish species (sole, spiny dogfish, smooth-hound, mackerel, swordfish, grey mullet, cod, anchovy, red mullet, Atlantic horse mackerel, tuna fish and mussel) collected in central Italian markets accounting for a total of 44 samples. Generally, ΣPBDEs showed higher concentration than ΣHBCDs except in the case of mussels in which ΣHBCDs > ΣPBDEs. Cod and smooth-hound are the least contaminated species among those analysed in the present study, whereas the highest brominated flame retardant (BFR) levels were found in spiny dogfish samples. The measured contamination levels were generally comparable to or lower than those already published in European studies. Literature data for HBCDs in European fish and shellfish were hard to find; therefore, PBDE and HBCD levels were also compared with European Environmental Quality Standard (EQS) in biota (Directive 2013/39/EU). EQSs for HBCDs are six orders of magnitude higher than those for PBDEs; therefore, while no exceedance was observed for the first, almost all the samples analysed for PBDEs were above EQSs. The presented preliminary data on PBDEs and HBCDs are among the first published in marine fish and shellfish commercialised in Central Italy. Graphical abstrac.

Sample Pretreatment Method for Determination of Indicator Polychlorinated Biphenyls in Seafood using Ultrasonic Extraction Followed by Dispersive Solid-Phase Extraction and Gas Chromatography - Electron Capture Detection.

A simple, rapid and novel method has been developed and validated for the determination of seven indicator polychlorinated biphenyls (PCBs) in seafood samples by gas chromatography coupled to electron capture detector. Freeze-dried samples were done first ultrasonic extraction by n-hexane:methylene chloride:acetone (3:1:1, v/v), and then one-step clean-up (dispersive solid-phase extraction clean-up) or two-step clean-up (concentrated sulfuric acid purification and dispersive solid-phase extraction clean-up) was selected according to the lipid contents of the samples, if the lipid content was no more than 1%, one-step clean-up was used, otherwise, two-step clean-up was chose. The linearity of this method ranged from 1.25 to 100 μg/L, with regression coefficients ranging between 0.9991 and 0.9998. The limits of detection were in low ng/g level, ranging between 0.005 and 0.0076 ng/g (wet weight). The recoveries of spiked seven PCBs with external calibration method at different concentration levels in Pseudosciaena polyactis, Penaeus vannamei and Sinonovacula constricta were in the range of 78-105%, 73-110% and 75-107%, respectively, and with relative standard deviations of 3.3-5.1%, 3.5-6.3% and 3.4-5.1% (n = 5), respectively. The performance of the proposed method was also compared with traditional soxhlet extraction and column chromatography clean-up on the same real seafood samples and comparable efficiencies were obtained. It is concluded that this method can be successfully applied for the determination of PCBs in different seafood samples.

Simultaneous determination of 106 pesticides in nuts by LC-MS/MS using freeze-out combined with dispersive solid-phase extraction purification.

As a result of the low water content and high fat matrices in nuts, it is very difficult to simultaneously determine multi-pesticides in trace levels. Here, a sample pretreatment method was developed in which, microwave-assisted solvent extraction was firstly used to extract pesticides, and then a two-step cleanup method was conducted combining freeze-out with dispersive solid-phase extraction to remove the lipidic matrix. By this way, 106 pesticides were simultaneously determined in the complicated nut sample by using an ultra-high pressure liquid chromatography coupled with a tandem mass spectrometer. Average recoveries were 75.3-119.3% with relative standard deviations<14% at three concentration levels. The limits of detection and quantification were in the ranges of 0.3-3.0 and 1.0-10.0μg/kg, respectively. Furthermore, the method was successfully applied to the determination of pesticides in 180 commercial nut samples.

Two-step cleanup procedure for the identification of carotenoid esters by liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry

Carotenoids are naturally found in both free form and esterified with fatty acids in most fruits; however, up to now the great majority of studies only evaluated their composition after saponification. This fact is easily explained by the difficult to analyze carotenoid esters. Preliminary studies showed that cleanup procedures in the extract are necessary for further analysis by LC⿿MS/MS since triacylglycerols (TAGs) impair the MS detection. Considering these facts, we developed a new cleanup procedure to remove TAGs and other lipids from carotenoid fruit extracts. This procedure is based on physical removal of solid lipids at low temperature followed by open column chromatography on MgO and diatomaceous earth. Before cleanup, four carotenoid diesters and two free xanthophylls were identified in murici (Byrsonyma crassifolia), corresponding to about 65% of the total chromatogram area. After carrying out the two-step cleanup procedure, 35 carotenoids were identified, being 14 monoesters, six free carotenoids and 15 carotenoid diesters. We can conclude that this two-step procedure was successfully applied to murici, an Amazonian fruit, which contains high amounts of lipids.

Determination of halogenated flame retardants in food: Optimization and validation of a method based on a two-step clean-up and gas chromatography–mass spectrometry

In this work, a new simple method based on a two-step clean-up and gas chromatography–mass spectrometry analysis for the determination of emerging halogenated flame retardants (HFRs), such as dechlorane plus (DP) and brominated phthalates, and polybrominated diphenyl ethers (PBDEs) in different food items was optimized and validated. Several types of food items, i.e. fish (smoked salmon and cod fillet), meat (chicken breast), chicken eggs, cow milk, and extra virgin olive oil, were chosen as representative matrices of the main food categories. After lyophilisation, the food samples were extracted using acetonitrile:toluene (9:1, v/v). As interferences, such as lipids and pigments, were co-extracted, a two-step clean-up (including Florisil and acid silica) was performed to efficiently remove them prior to GC–MS analysis in electron capture negative ionization mode (GC–ECNI/MS). The performance criteria established by the European Commission (2014/118/EU) were achieved with this method for all target analytes, except for the LOQ achieved for BDE-209 (0.1 ng/g wet weight, ww). The trueness ranged between 75 and 125% for most compounds and the matrices analyzed and the repeatability (expressed as RSD%) was <20%, within the set performance criteria. The method was then used for the determination of PBDEs and emerging HFRs in 20 different food items purchased from Antwerp supermarkets, revealing a prevalent contamination with PBDEs (up to 2.02 ng/g ww) and tribromoanisole (up to 6.6 ng/g ww) in the fish/seafood category.

Determination of the sum of short chain chlorinated n-alkanes with a chlorine content between 50% and 67% in sediment samples by GC–ECNI-MS and quantification by multiple linear regression

A method for the quantification of the sum of short chain chlorinated paraffins (SCCPs) by GC–ECNI-MS was developed. This method is suited to the special demands of environmental sediment analysis using an approach of sum determination by multiple regression quantification and is independent of the chlorine content as well as robust against changes in C-number distribution of the SCCPs to be analysed. The method is based on the integration of the signals for two selected m/z values (375 and 423) over the full retention range of the SCCPs. The calibration is performed using three synthetic mixtures representing the variety of SCCP-mixtures as found in environmental samples as well as in technical mixtures. Quantification is performed using a multiple linear regression calibration with two selected m/z value signals achieving an LOQ of 0.6μg/g sediment.The proposed quantification procedure for sediments was verified by 16 independently prepared and differently composed SCCP-mixtures mimicking a variety of sediment samples quoted in literature.For the analysis of the sediment samples a two-step clean-up was applied comprising a column chromatographic clean-up and GPC.The method allows for a standardized analysis according to the European water framework directive, especially in the case of trend monitoring of sediments.

Structural characterization of the N-glycosylation of individual soybean β-conglycinin subunits

Soybean (Glycine max) 7S β-conglycinin is a seed storage protein consisting of homo- and hetero-trimers of three subunits, namely α (∼67kDa), α′ (∼71kDa), and β (∼50kDa), non-covalently associated. The N-glycans released from the whole β-conglycinin have been already characterized by 1H NMR some decades ago. Nevertheless, the actual glycosylation of the potential sites and the glycoforms of the individual subunits have not been specifically investigated so far. In this study, up-to-date chromatographic, electrophoretic and mass spectrometric strategies have been combined to achieve the structural characterization of the glycoforms of the three individual β-conglycinin subunits. Glycosylation sites were assigned by analyzing the tryptic glycopeptides of the isolated subunits. Underivatized N-glycans were purified with a two-step clean-up, consisting in sequential reversed-phase and activated porous graphitized carbon micro-chromatography, and profiled by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS).

Microwave-assisted extraction combined with gel permeation chromatography and silica gel cleanup followed by gas chromatography–mass spectrometry for the determination of organophosphorus flame retardants and plasticizers in biological samples

An analytical method for the determination of 14 organophosphorus flame retardants (OPFRs), including halogenated OPFRs, non-halogenated OPFRs and triphenyl phosphine oxide (TPPO) in biological samples was developed using gas chromatography–mass spectrometry (GC/MS). Biological samples were extracted using microwave-assisted extraction (MAE) with hexane/acetone (1:1, v/v) as the solvent; then, a two-step clean-up technique, gel permeation chromatography (GPC) combined with solid phase extraction (SPE), was carried out before GC/MS analysis. Experimental results showed that the developed method efficiently removed the lipid compounds and co-extract interferences. Moreover, using the relatively “narrow” column (with an i.d. of 10mm) significantly decreased the elution volume and, therefore, prevented the loss of the most volatile OPFRs, especially trimethyl phosphate (TMP) and triethyl phosphate (TEP). The method detection limits (MDLs) for OPFRs in the biological samples ranged from 0.006 to 0.021ngg−1lw, and the recoveries were in the range of 70.3–111%, except for TMP (38.9–55.6%), with relative standard deviations (RSDs) of less than 14.1%. The developed method was applied to determine the amount of the target OPFRs in biological samples (i.e., fish and domestic birds) that were collected from the Pearl River Delta (PRD) region in southern China. Of the 14 OPFRs, tri-n-butyl phosphate (TnBP), tris(2-chloroethyl) phosphate (TCEP), tris(chloropropyl) phosphate (TCPP) and tributoxyethyl phosphate (TBEP) were present in all of the biological samples that were analyzed, and dominated by TnBP, TCEP and TBEP. The concentrations of OPFRs in the biological samples that were collected from the PRD region were higher than those reported in other locations.

Optimized cleanup method for the determination of short chain polychlorinated n-alkanes in sediments by high resolution gas chromatography/electron capture negative ion–low resolution mass spectrometry

The performances of three adsorbents, i.e. silica gel, neutral and basic alumina, in the separation of short chain polychlorinated n-alkanes (sPCAs) from potential interfering substances such as polychlorinated biphenyls (PCBs) and organochlorine pesticides were evaluated. To increase the cleanup efficiency, a two-step cleanup method using silica gel column and subsequent basic alumina column was developed. All the PCB and organochlorine pesticides could be removed by this cleanup method. The very satisfying cleanup efficiency of sPCAs has been achieved and the recovery in the cleanup method reached 92.7%. The method detection limit (MDL) for sPCAs in sediments was determined to be 14 ng g −1. Relative standard deviation (R.S.D.) of 5.3% was obtained for the mass fraction of sPCAs by analyzing four replicates of a spiked sediment sample. High resolution gas chromatography/electron capture negative ion–low resolution mass spectrometry (HRGC/ECNI–LRMS) was used for sPCAs quantification by monitoring [M−HCl] − ions. When applied to the sediment samples from the mouth of the Daliao River, the optimized cleanup method in conjunction with HRGC/ECNI–LRMS allowed for highly selective identifications for sPCAs. The sPCAs levels in sediment samples are reported to range from 53.6 ng g −1 to 289.3 ng g −1. C 10- and C 11-PCAs are the dominant residue in most of investigated sediment samples.

Validation of the Determination of Chloramphenicol Residues in Animal Feed by Liquid Chromatography with an Ion Trap Detector Based on European Decision 2002/657/EC

A new liquid chromatographic method with an ion trap detector for the determination of chloramphenicol residues in animal feed is described. The developed method consists of an organic extraction and a two-step cleanup. For the cleanup, solid phase and liquid–liquid extractions were applied to minimize the ion suppression effects. One precursor and three product ions were monitored obtaining 5.5 identification points, which provided the method with a very high selectivity/specificity and gave a great confidence to the results. The described method was fully validated according to the requirements of the 2002/657/EC European Decision and the estimated decision limit and detection capability were 6 and 8 μg Kg−1, respectively.

Analytical characteristics and determination of major novel brominated flame retardants (NBFRs) in indoor dust

A new method was developed and optimized for the detection of major "novel" brominated flame retardants (NBFRs), which included decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), tetrabromobisphenol A-bis(2,3-dibromopropylether) (TBBPA-DBPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) and hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO). Several solid phase sorbents were tested, and finally, a two-step cleanup procedure was established. The first step on activated silica was used to fractionate the dust extracts, while the second step on acidified silica (silica gel impregnated with sulphuric acid 44% w/w) and on Florisil(®), respectively, was essential for advanced cleanup. High recoveries for NBFRs (range, 75-94%) were achieved. Analysis was performed by gas chromatography coupled with mass spectrometry in electron capture negative ionization using a DB-5ms (15 m × 0.25 mm × 0.1 μm) capillary column. Quantification of DBDPE, BTBPE and TBBPA-DBPE was based on ion m/z 79, while characteristic ions were used for quantification of TBB (m/z 359), HCDBCO (m/z 310) and TBPH (m/z 384). The method provided good repeatability; within- and between-day precision were ≤14% for all NBFRs. Method limits of quantification ranged between 1 and 20 ng g(-1); dust and NBFRs were not detected in blanks. The method was further applied to indoor dust (n = 21) collected from e-waste facilities in Thailand. Except for HCDBCO, all NBFRs were detected in the e-waste dust with concentrations up to 44,000 and 22,600 ng g(-1) DBDPE and BTBPE, respectively. The dust profile was dominated by DBDPE (50%) > BTBPE (45%) > TBBPA-DBPE (3%) > TBPH (1.9%) > TBB (0.1%). Significant correlations (p < 0.05) were found between the concentrations of BTBPE and BDE 183 or BDE 197 on the one hand, between TBPH and BDE 47 or BDE 99, and between DBDPE and BDE 209, on the other hand. Concentrations of TBB were not positively correlated with TBPH, which suggests different emission sources.

Multi-residue analysis of PAH, PCB, and OCP optimized for organic matter of forest soil

Analyzing organic pollutants in forest soil is challenging because they are strongly physical and chemical bound to soil organic matter (SOM). Within the framework of a forest soil inventory, an analytical protocol for the determination of polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and organochlorine pesticides (OCP) should be established and validated using one and the same extraction and cleanup procedure. The protocol should be applicable for reliable analysis of a high number of samples in a short timeframe. Two different soil samples representative for the humic layer from a typical mixed and coniferous forest soil had been used for the analysis. Three solvents of different polarity, namely cyclohexane (CH), ethylacetate (EA)/CH (1/1, v/v), and acetone (AC)/CH (2/1, v/v), and the six standard extraction techniques (pressurized liquid extraction (PLE), soxhlet extraction, fluidized bed extraction, sonication, shaking, and one-step extraction recommended for analyzing agricultural soil in Germany (VDLUFA 2008)) were compared concerning their extraction efficiency. For additional matrix separation, two different cleanup procedures (gel permeation chromatography (GPC) and solid-phase extraction (SPE) with different sorbents) were tested. Quantification was carried out using gas chromatography combined with mass spectrometry (GC–MS) and two different injection systems (split/splitless injection and programmable temperature vaporizer (PTV) injection). Labeled internal standards, added prior to extraction, were used for method evaluation. For the simultaneous extraction of PAH, PCB, and OCP from organic forest soil PLE with acetone/cyclohexane (2/1, v/v) provided the highest extraction efficiency. A two-step cleanup procedure consisting of GPC followed by SPE with silica gel was entirely sufficient for the separation of humic substances without discrimination of analytes. Recovery rates for the different extraction and cleanup steps ranged between 89% and 106%. For quantification, a GC–MS method was developed using two different injection systems and two capillary columns of different selectivity. By comparing six standard extraction techniques for PAH, PCB, and OCP from forest soil, we obtained the highest extraction efficiency when using PLE with AC/CH (2/1). For sample injection, we achieved best results using an optimized PTV injection system as it highly reduced the breakdown of thermolabile pesticides. Using this combination of technical equipment, it is possible to determine a concentration of the analytes in the trace level range of 1–2 μg kg−1 in humic soil.

How to decrease ion suppression in a multiresidue determination of β-agonists in animal liver and urine by liquid chromatography–mass spectrometry with ion-trap detector

A new liquid chromatography–mass spectrometry with ion-trap detection method for the determination of clenbuterol, ractopamine, clenpenterol, brombuterol, hydroxyclenbuterol, mapenterol and mabuterol in animal liver and urine is described to decrease ion suppression in both matrices. The developed method consists of an aqueous extraction and a two-step clean-up. Final extract was injected in a liquid chromatograph with ion trap mass spectrometer optimized to obtain MS 3 ions which provided more specificity and better signal to noise ratio in the investigated analytes. Those steps have been essential to reach decision limits (CCα) values below the proposed MRPL values for each substance. The CCα were determined and their values were 0.05 μg kg −1 for clenbuterol, 0.2 μg kg −1 for ractopamine and 0.1 μg kg −1 for the other analytes in liver and the same values in μg L −1 for urine samples.

Improved cleanup technique for gas chromatographic–mass spectrometric determination of alkylphenols from biota extract

A simple and economical cleanup technique was developed to determine alkylphenols by GC–MS from biological extracts containing relatively high lipids. The lipids were successfully removed from bivalve extracts through a two-step cleanup. The new method is a combination of Florisil adsorption chromatography and silyl derivatization technique. Low and high (non-polar and highly polar) molecular weight lipids were removed from the biota extract with deactivated Florisil column in the first step. And in the second step, middle molecular weight (middle polar) lipids were removed in an activated Florisil column after the alkylphenols were converted to corresponding silyl derivatives with bis(trimethylsilyl)trifluoroacetamide (BSTFA). On the basis of the above results, a simple cleanup kit was developed for convenience. The technique was optimized with reference to the activity of packing materials and polarity of eluting solvents. Only 3 g of Florisil, 25 mL of hexane and 10 mL of dichloromethane were required for one sample. The recoveries of alkylphenols from spiked samples varied from 88 to 103% with a low relative standard deviation (mean value: 5.3%) and the recovery was similar or even higher than other methods currently in use. The technique was successfully applied to mussel samples from Masan Bay, South Korea. Simultaneous measurement of these compounds in water, sediment and biota; the resulting bio-concentration factor and their relationships confirm previously published works, validating the method applied.

Development of an analytical method for the determination of the residues of four pyrethroids in meat by GC–ECD and confirmation by GC–MS

The development of an analytical method for the determination of four selected pyrethroid insecticides at residue level in beef meat is presented. Acetone and petroleum ether at 40-60 degrees C were chosen as extraction solvents. A two-step clean-up was performed using an Extrelut NT3-C(18) system followed by a Florisil column, with disposable, ready-to-use cartridges. Instrumental analysis was carried out on a gas chromatograph equipped with an electron capture detector (GC-ECD), using matrix-matched and internal standard calibration techniques. Confirmatory analysis by GC-MS was performed. Recoveries at the EU Maximum Residue Limit (MRL), 0.5 x MRL and 1.5 x MRL levels and the repeatabilities were widely satisfactory. The main advantage of the method was the reduction of analysis time as compared with previously published works. The applicability of the method to different matrices and pesticide classes will be investigated.

Determination of resorcylic acid lactones in biological samples by GC–MS. Discrimination between illegal use and contamination with fusarium toxins

An EU project, FAIR5-CT-1997-3443, has been undertaken to distinguish illegal use of zeranol from consumption of food contaminated with Fusarium spp. toxin. One of the tasks was development of screening and confirmatory methods of analysis. This paper describes a new method based on two-step clean-up and GC-MS analysis. The first clean-up step is matrix-dependant; the second is applicable to both urine and meat. The MS is operated in negative chemical ionisation mode. The method is quantitative for zeranol and taleranol, alpha- and beta-zearalenol, and zearalenone and qualitative for zearalanone. Validation was performed according to the latest EU performance criteria (Commission Decision 2002/657). For analysis of urine CC(alpha) and CC(beta) for the method (microg L(-1)) were 0.06-0.11 for zeranol, 0.07-0.12 for taleranol, 0.07-0.11 for alpha-zearalenol, 0.21-0.36 for beta-zearalenol, 0.35-0.60 for zearalenone, and 0.19-0.33 zearalanone. Within-laboratory reproducibility was 16.2, 11.2, 31.9, 30.1, 26.6, and 54.2% for zeranol, taleranol, alpha-zearalenol, beta-zearalenol, zearalenone, and zearalanone, respectively. It was found that all the compounds are stable in urine at -20 degrees C for at least a year. Part of the validation program was organisation of a small proficiency study (ringtest) and a correlation study with an LC-MS-MS method developed by the Veterinary Science Division (VSD; Belfast, UK-NI). This study showed there was good correlation between results from both laboratories. The method can be used for quantitative analysis discriminating illegal use of zeranol from consumption of zearalenone-contaminated food.

Pretreatment procedure for selenium speciation in shellfish using high‐performance liquid chromatography–microwave‐assisted digestion–hydride generation‐atomic fluorescence spectrometry

AbstractA pretreatment procedure based on an enzymatic hydrolysis extraction followed by a two‐step clean‐up has been performed for selenium speciation in shellfish samples. Bivalve samples were extracted with protease XIV, lipase VII and protease VIII. By using a protease VIII–lipase VII mixture, quantitative recoveries were obtained for all the selenium species, except for selenocystine (59%). Owing to the complexity of the matrix, clean‐up procedures were required to remove interferents that affected the chromatographic separation. The extracts were first partitioned in dichloromethane and then passed through a column with aminopropylsilane. Speciation of selenocystine, selenomethionine, selenoethionine, selenite and selenate was obtained using a high‐performance liquid chromatography–microwave‐assisted digestion–hydride generation‐atomic fluorescence spectrometry coupling. The chromatographic system consisted of an anion exchange and a reversed‐phase column, both connected through a six‐port switching valve. On‐line microwave‐assisted digestion and hydride generation steps were performed prior to atomic fluorescence detection. The method was applied to clam and prawn samples collected from the southwest coast of Spain. Copyright­© 2002 John Wiley &amp; Sons, Ltd.

Polychlorinated biphenyls and organochlorine pesticides in soils from the southern part of Poland.

Surface soil and sediment samples collected from the cities of Kraków, Katowice, and Chorzow in 1993-94 were analyzed to determine the residual levels of persistent organochlorine pesticides (HCB, HCHs, DDTs, CHLs) and polychlorinated biphenyls (PCBs). Detection, identification, and quantification were made after a two-step clean-up and fractionation of sample extract with concentrated sulfuric acid and Florisil gel, followed by capillary gas chromatography with a 63Ni electron capture detector (GC-ECD) or a mass selective detector (GC-LRMS). The soil from the city of Katowice is relatively more polluted, mainly by PCBs but also by the other organochlorines. Both the soil in the cities of Kraków and Katowice are more polluted by organochlorines than soil from many other places in Poland. The residual concentrations of the organochlorines indicated nonexistence of the domestic sources of pollution by CHLs and elevated local contamination with PCBs. Sediment contained PCBs and CHLs in much higher concentrations than found in soil. In the case of DDTs, HCHs and HCB, the concentrations were of the same order of magnitude. Composition of DDT metabolites and of HCH isomers were investigated in detail.