Sol–gel polydimethylsiloxane/poly(vinylalcohol)‐coated stir bar sorptive extraction of organophosphorus pesticides in honey and their determination by large volume injection GC

A PDMS/poly(vinylalcohol) (PDMS/PVA) film prepared through a sol–gel process was coated on stir bars for sorptive extraction, followed by liquid desorption and large volume injection–GC–flame photometric detector (LVI–GC–FPD) for the determination of five organophosphorus pesticides (OPPs) (phorate, fenitrothion, malathion, parathion, and quinalphos) in honey. The preparation reproducibility of PDMS/PVA‐coated stir bar ranged from 4.3 to 13.4% (n = 4) in one batch, and from 6.0 to 12.6% (n = 4) in batch to batch. And one prepared stir bar can be used for more than 50 times without apparent coating loss. The significant parameters affecting stir bar sorptive extraction (SBSE) were investigated and optimized. The LODs for five OPPs ranged from 0.013 (parathion) to 0.081 μg/L (phorate) with the RSDs ranging from 5.3 to 14.2% (c = 1 μg/L, n = 6). The proposed method was successfully applied to the analysis of five OPPs in honey.     

Molecularly imprinted stir bars for selective extraction of thiabendazole in citrus samples

Stir‐bar sorptive extraction is based on the partitioning of target analytes between the sample (mostly aqueous‐based liquid samples) and a stationary phase‐coated magnetic stir bar. Until now, only PDMS‐coated stir bars are commercially available, restricting the range of applications to the non‐selective extraction of hydrophobic compounds due to the apolar character of PDMS. In this work, a novel stir bar coated with molecularly imprinted polymer as selective extraction phase for sorptive extraction of thiabendazole (TBZ) was developed. Two different procedures, based on physical or chemical coating, were assessed for the preparation of molecularly imprinted stir bars. Under optimum conditions, recoveries achieved both in imprinted and non‐imprinted polymer stir bars obtained by physical coating were very low, whereas TBZ was favourably retained by imprinted over non‐imprinted polymer stir bars obtained by chemical coating and thus the latter approach was used in further studies. Different parameters affecting both stir‐bars preparation (i.e. cross‐linker, porogen, polymerization time) and the subsequent selective extraction of TBZ (i.e. washing, loading and elution solvents, extraction time) were properly optimized. The molecularly imprinted coated stir bars were applied to the extraction of TBZ from citrus samples (orange, lemon and citrus juices) allowing its final determination at concentrations levels according to current regulations.     

pH-resistant titania hybrid organic-inorganic coating for stir bar sorptive extraction of drugs of abuse in urine samples followed by high performance liquid chromatography-ultraviolet visible detection

An organic-inorganic hybrid titania-hydroxy-terminated silicone oil (titania-OH-TSO) stir bar coating was prepared by sol-gel method. The extraction performance of titania-OH-TSO coated stir bar was evaluated and compared with poly(dimethysiloxane) (PDMS), poly(dimethysiloxane)-divinylbenzene (PDMS-DVB), poly(dimethysiloxane)-β-cyclodextrin (PDMS-β-CD) and C(18) coated stir bar with five polar drugs of abuse including amphetamine (PA), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and ketamine (Ke) as the model analytes. The experimental results revealed that the titania-OH-TSO coated stir bar exhibited highly pH-resistant ability, good preparation reproducibility, superior selectivity and high extraction efficiency for the target compounds. Based on this fact, a new method of titania-OH-TSO coated stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography (HPLC)-ultraviolet visible (UV) detection was developed for the analysis of five drugs of abuse in urine samples. The factors affecting the extraction efficiency of SBSE such as sample pH, desorption solvent, sample volume, extraction time, desorption time, stirring rate and ionic strength were investigated and the optimal extraction conditions were established. Under the optimized conditions, the limits of detection (LODs) for titania-OH-TSO coated SBSE-HPLC-UV determination of five polar drugs of abuse were in the range of 2.3-9.1 μg/L with relative standard deviations (RSDs) ranging from 7.3 to 8.9% (c=300 μg/L, n=6), and all of the target compounds exhibited good linearity over a concentration range of 30-3000 μg/L. The developed method was applied to the determination of amphetamines and Ke in urine samples of drug abusers with satisfactory results.     

Poly(phthalazine ether sulfone ketone) as novel stationary phase for stir bar sorptive extraction of organochlorine compounds and organophosphorus pesticides

A novel poly(phthalazine ether sulfone ketone) (PPESK) film prepared by immersion precipitation technique was coated on stir bars for sorptive extraction. Scanning electron micrographs showed that the coating has a denser porous surface (about 1 microm in thickness) with a sponge-like sublayer, and the thickness of the coating was 250 microm. The PPESK coated stir bar has high thermostability (290 degrees C) and long lifetime (50 times). The extraction properties of this stir bar were evaluated for the extraction of both polar and semi-polar analytes, including organochlorine compounds and organophosphorus pesticides. The PPESK stir bar was proved to show higher affinity towards polar compounds than that of PDMS coated stir bar and higher sample load compared with corresponding PPESK fiber. It was applied to the determination of organochlorine compounds in seawater samples and organophosphorus pesticides in juices by gas chromatographic analysis. The effect of sample matrix was evaluated at optimized condition of extraction temperature, extraction time and salt concentration. Limits of detection were in the range of 0.05-2.53 ng L(-1) for organochlorine compounds in seawater samples using electron capture detector (ECD), with precisions of less than 11% RSD. Limits of detection for organophosphorus pesticides were in the range of 0.17-2.25 ng L(-1) and 2.47-10.3 ng L(-1) in grape and peach juice, respectively, using thermionic specified detector (TSD), with precisions of less than 12% RSD and 20% RSD, respectively.     

Quantitative analysis of perfumes in talcum powder by using headspace sorptive extraction

Quantitative analysis of perfume dosage in talcum powder has been a challenge due to interference of the matrix and has so far not been widely reported. In this study, headspace sorptive extraction (HSSE) was validated as a solventless sample preparation method for the extraction and enrichment of perfume raw materials from talcum powder. Sample enrichment is performed on a thick film of poly(dimethylsiloxane) (PDMS) coated onto a magnetic stir bar incorporated in a glass jacket. Sampling is done by placing the PDMS stir bar in the headspace vial by using a holder. The stir bar is then thermally desorbed online with capillary gas chromatography-mass spectrometry. The HSSE method is based on the same principles as headspace solid-phase microextraction (HS-SPME). Nevertheless, a relatively larger amount of extracting phase is coated on the stir bar as compared to SPME. Sample amount and extraction time were optimized in this study. The method has shown good repeatability (with relative standard deviation no higher than 12.5%) and excellent linearity with correlation coefficients above 0.99 for all analytes. The method was also successfully applied in the quantitative analysis of talcum powder spiked with perfume at different dosages.     

Development of new polar monolithic coatings for stir bar sorptive extraction

Polar vinyl monomers have been used for the synthesis of several polymer monoliths, to serve as novel coatings for stir bar sorptive extraction; the monovinyl monomers 2‐hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) monomethacrylate) (PEGMA) were copolymerized with (apolar) divinylbenzene (DVB) and/or pentaerythritol triacrylate (PETRA), both of which are cross‐linking agents. After the optimization of the most important synthesis parameters, which included the ratio between total monomers and porogen, the nature of the porogen, and the monomer ratios, inter alia, three mechanically stable, polar monolithic coatings for stir bar sorptive extraction were obtained that were based on poly(HEMA‐co‐DVB), poly(HEMA‐co‐PETRA), and poly(PEGMA‐co‐PETRA). Thereafter, and in order to evaluate the hydrophilicity of the resulting monoliths, they were applied as materials in the stir bar sorptive extraction of a group of emerging pollutants with a wide range of polarities. The results showed that both the poly(HEMA‐co‐DVB) and poly(PEGMA‐co‐PETRA) materials could be used to extract both polar and nonpolar compounds by stir bar sorptive extraction, in an effective manner. Taking into account the desired chemical and morphological properties, as well as the extraction efficiencies, the poly(PEGMA‐co‐PETRA) material seemed to be a particularly promising monolith for application as a novel coating in stir bar sorptive extraction.     

Stir bar sorptive extraction for the analysis of short‐chain chlorinated paraffins in water

An optimised method using stir bar sorptive extraction (SBSE) and a thermal desorption‐GC‐electron capture detector (GC‐ECD) for the determination of short‐chain chlorinated paraffins from water samples was developed. Recoveries near to 100% were obtained by using 20 mm×0.5 mm (length×film thickness) PDMS commercial stir bars from 200 mL spiked water samples and 20% methanol addition with an extraction period of 24 h. Method sensitivity, linearity and precision were evaluated for surface water and wastewater spiked samples. A LOD of 0.03 and 0.04 μg/L was calculated for surface and wastewater, respectively. The precision of the method given as an RSD was below 20% for both matrices. The developed method was applied for the analysis of two real samples from a contaminated river and a wastewater treatment plant. Results were in accordance with those obtained using a previously developed method based on solid phase microextraction (SPME).     

Sol-gel coated polydimethylsiloxane/beta-cyclodextrin as novel stationary phase for stir bar sorptive extraction and its application to analysis of estrogens and bisphenol A

A sol-gel technique was used for the preparation of a stir bar coated with a composite composed of polydimethysiloxane and beta-cyclodextrin (PDMS/beta-CD). The sol-gel mechanism during coating procedure was discussed and successful binding of beta-CD to the sol-gel network was confirmed by the IR spectra. Scanning electron micrographs of the stir bars revealed a homogeneous surface with a film thickness of 30-150 microm attributing to different coating times. Good thermal stability and solvent-resistance of the stir bar were found thanks to chemical binding formed between the stationary phase and the glass substrate. The PDMS/beta-CD coated stir bar was proved to have better selectivity to polar compounds compared to the PDMS coated stir bar, and higher extraction capacity compared to the corresponding PDMS/beta-CD coated fiber. Methods for the determinations of estrogens in environmental water, bisphenol A in drinking water and in leachate of one-off dishware by the PDMS/beta-CD coated stir bar coupled with high-performance liquid chromatography (HPLC) were developed. The limits of detection were within the range of 0.04-0.11 microg l(-1) for estrogens using UV detection and 8 ngl(-1) for bisphenol A using fluorescence detection. Reproducibility with RSD less than 9.7% for extractions of real water samples at microg l(-1) or ngl(-1) level was obtained.     

Development of a carbon‐nanoparticle‐coated stirrer for stir bar sorptive extraction by a simple carbon deposition in flame

Stir bar sorptive extraction is an environmentally friendly microextraction technique based on a stir bar with various sorbents. A commercial stirrer is a good support, but it has not been used in stir bar sorptive extraction due to difficult modification. A stirrer was modified with carbon nanoparticles by a simple carbon deposition process in flame and characterized by scanning electron microscopy and energy‐dispersive X‐ray spectrometry. A three‐dimensional porous coating was formed with carbon nanoparticles. In combination with high‐performance liquid chromatography, the stir bar was evaluated using five polycyclic aromatic hydrocarbons as model analytes. Conditions including extraction time and temperature, ionic strength, and desorption solvent were investigated by a factor‐by‐factor optimization method. The established method exhibited good linearity (0.01–10 μg/L) and low limits of quantification (0.01 μg/L). It was applied to detect model analytes in environmental water samples. No analyte was detected in river water, and five analytes were quantified in rain water. The recoveries of five analytes in two samples with spiked at 2 μg/L were in the range of 92.2–106% and 93.4–108%, respectively. The results indicated that the carbon nanoparticle‐coated stirrer was an efficient stir bar for extraction analysis of some polycyclic aromatic hydrocarbons.     

Spiral stir bar sorptive extraction with polyaniline‐polydimethylsiloxane sol‐gel packings for the analysis of trace estrogens in environmental water and animal‐derived food samples

A spiral stir bar was proposed by using stainless steel spring as the extraction phase carrier to avoid the extraction phase friction and increase the amount of extraction phase for improving extraction efficiency. The extraction phase is filled in the cavity of the spring, resulting in a larger amount of the extraction phase than that conventionally coated on glass stir bar or stainless steel wire. Polyaniline‐polydimethylsiloxane sol‐gel packed spiral stir bar was prepared and evaluated for the extraction of five estrogens. The prepared spiral stir bar presented good extraction efficiency/preparation reproducibility and long lifetime (more than 150 reused times) for target estrogens. Based on it, a method of spiral stir bar sorptive extraction combined with high performance liquid chromatography coupled with ultra‐violet detection was developed for the analysis of trace estrogens in environmental and food samples. The detection limit for five estrogens was 0.11–.31 µg/L, with the enrichment factors of 83.0–118‐fold (maximal enrichment factor: 200‐fold). The reproducibility evaluated with each estrogen of 5 µg/L (n = 5) was 5.8–8.9%. The method was successfully applied for the determination of estrogens in environmental water and animal‐derived food samples.     

Novel combined stir bar sorptive extraction coupled with ultrasonic assisted extraction for the determination of brominated flame retardants in environmental samples using high performance liquid chromatography

A combined stir bar coated with poly (dimethysiloxane)-beta-cyclodextrin (PDMS-beta-CD) on single side has been prepared for the first time by sol-gel method and was coupled with ultrasonic assisted extraction (UAE) for the determination of some brominated flame-retardant compounds (BFRs) in soil and dust samples by high performance liquid chromatography (HPLC). Four different kinds of coatings including PDMS-beta-CD, PDMS, carbowax (CW)-PDMS-poly (vinyl alcohol) (PVA) and PDMS-PVA were evaluated for stir bar sorptive extraction of BFRs by orthogonal experiment design. The experimental results reveal that the PDMS-beta-CD combined stir bar exhibited the best extraction efficiency for the target analytes. The reproducibility for the preparation of PDMS-beta-CD combined stir bar ranged from 1.3% to 15.7% in one batch, and 7.2% to 15.1% among batches. Extraction time, desorption solvent, concentration of methanol and NaCl in the matrix, pH, temperature and stirring speed were optimized. The combined stir bar can avoid direct friction of the coating with the bottom of the vessel, and could be used for more than 100 times. Linearity (>0.993), repeatability (<10.5%), reproducibility (<16.5%), recovery (56-118%) and detection limits (2.9-4.2 microg L(-1)) were proper to determine the seven BFRs. The developed method was applied to the determination of BFRs in soil and dust with satisfactory results.     

A novel HS-SBSE system coupled with gas chromatography and mass spectrometry for the analysis of organochlorine pesticides in water samples

A methodology to analyze organochlorine pesticides (OCPs) in water samples has been accomplished by using headspace stir bar sorptive extraction (HS-SBSE). The bars were in house coated with a thick film of PDMS in order to properly work in the headspace mode. Sampling was done by a novel HS-SBSE system whereas the analysis was performed by capillary GC coupled mass spectrometric detection (HS-SBSE-GC-MS). The extraction optimization, using different experimental parameters has been established by a standard equilibrium time of 120 min at 85 degrees C. A mixture of ACN/toluene as back extraction solvent promoted a good performance to remove the OCPs sorbed in the bar. Reproducibility between 2.1 and 14.8% and linearity between 0.96 and 1.0 were obtained for pesticides spiked in a linear range between 5 and 17 ng/g in water samples during the bar evaluation.     

Preparation of sol-gel polyethylene glycol-polydimethylsiloxane-poly(vinyl alcohol)-coated sorptive bar for the determination of organic sulfur compounds in water

A novel headspace sorptive extraction (HSSE) using a glass bar coated with carbowax (polyethylene glycol)-polydimethylsiloxane-poly(vinyl alcohol) (CW/PDMS/PVA) prepared by sol-gel technology method was proposed for the determination of volatile organic sulfur compounds (VOSs) in water. After the extraction, the sorptive bar was desorbed with 60 microL of ethanol and 30 microL of the extract was analysed by large volume injection (LVI) into a gas chromatography-flame photometric detector (GC-FPD). The parameters affecting the headspace sorptive extraction of VOSs such as extraction and desorption time, extraction temperature, stirring speed, desorption solvent, headspace phase ratio, salt and pH were carefully investigated and the optimized experimental conditions were established. The limits of detection (LODs) for the studied VOSs ranged from 0.04 to 4.8 microg/L with the relative standard deviations (RSDs) ranging from 4.5 to 10.2% (n=6). The reproducibility for the preparation of CW/PDMS/PVA-coated sorptive bar ranged from 3.2 to 9.2% in one batch, and from 2.8 to 18.5% in batch-to-batch, and more than 50 extractions can be achieved without apparent loss. The proposed method was compared with polydimethylsiloxane-HSSE and carboxen/PDMS-headspace-solid phase microextraction (CAR/PDMS-HS-SPME) under their optimum conditions, CW/PDMS/PVA-HSSE shows the highest adsorption capacity (larger surface area and more active sites), the highest sensitivity (about 10 times) and the best polarity matching for VOSs.     

Development and validation of stir bar sorptive extraction of polar phenols in water followed by HPLC separation in poly(vinylpyrrolididone‐divinylbenzene) monolith

An effective and simple method for polar phenols in water matrix was developed by using stir bar sorptive extraction (SBSE) based on a hydrophilic poly(vinylpyrrolididone‐divinylbenzene) (VPDB) monolithic material and HPLC analysis. To achieve optimum extraction performance for phenols, several parameters, including extraction and desorption time, desorption solvent, pH value, and ionic strength of sample matrix, were investigated. Under the optimized experimental conditions, eight phenols were directly enriched from water samples and analyzed by HPLC‐DAD. The detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target compounds were achieved within the range of 0.72–1.37 and 2.40–4.27 ng/mL from spiked water, respectively. Recoveries of eight phenolic compounds were found in the range of 55.2–95.9%. The calibration curves showed the linearity ranging from 5 to 150 ng/mL with linear regression coefficient R² values above 0.98. Method repeatability presented as intra‐ and interday precisions were also found with the RSDs less than 4.10 and 7.61%, respectively. The distribution coefficients between VPDB and water (K_VPDB/W) for phenolic compounds were also calculated and compared with K_O/W. Finally, the proposed method was successfully applied to the determination of the target compounds in tap water, sea water and wastewater samples.     

Stir bar sorptive extraction coupled to thermodesorption-gas chromatography-mass spectrometry for the determination of insect repelling substances in water samples

Stir bar sorptive extraction (SBSE) in combination with thermodesorption-gas chromatography-mass spectrometry (TD-GC-MS) was applied for the determination of eight insect repellents and synergists in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 20 mL of water sample with 4 g NaCl and stirred at 1000 rpm for 180 min. Then, the stir bar was subjected to TD-GC-MS. SBSE parameters (ionic strength, presence of organic solvent and time) were optimised. Blank contamination and carryover problems were also studied. The method affords detection limits between 0.5 and 30 ng/L, except for dimethyl phthalate (DMP) (150 ng/L) due to blank contamination problems. It shows good linearity with correlation coefficients over 0.997 and reproducibility (RSD) below 20%. The extraction efficiencies were between 29% for DMP and 80% for di-n-propyl isocinchomeronate (R-326). The feasibility of the method was tested by analysing real samples such as lake water, river water and wastewater.     

Development and application of a polar coating for stir bar sorptive extraction of emerging pollutants from environmental water samples

In the present study, a stir bar coated with hydrophilic polymer based on poly(N-vinylpyrrolidone-co-divinylbenzene) was prepared for the sorptive extraction of polar compounds. The main parameters affecting the polymerisation of the coating were investigated.The new stir bar was applied successfully in stir bar sorptive extraction with liquid desorption followed by liquid chromatography–mass spectrometry in tandem with a triple quadrupole for the determination of a group of polar pharmaceuticals and personal care products (PPCPs) in environmental water matrices. Different variables affecting extraction and desorption such as agitation speed, temperature, ionic strength and extraction time were optimised. The results showed that the stir bar is able to enrich the selected analytes effectively.The developed method was applied to determine a group of PPCPs in different complex environmental samples, including river, effluent and influent waste water.     

Polydimethylsiloxane/polypyrrole stir bar sorptive extraction and liquid chromatography (SBSE/LC-UV) analysis of antidepressants in plasma samples

A new polymeric coating consisting of a dual-phase, polydimethylsiloxane (PDMS) and polypyrrole (PPY) was developed for the stir bar sorptive extraction (SBSE) of antidepressants (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine and sertraline) from plasma samples, followed by liquid chromatography analysis (SBSE/LC-UV). The extractions were based on both adsorption (PPY) and sorption (PDMS) mechanisms. SBSE variables, such as extraction time, temperature, pH of the matrix, and desorption time were optimized, in order to achieve suitable analytical sensitivity in a short time period. The PDMS/PPY coated stir bar showed high extraction efficiency (sensitivity and selectivity) toward the target analytes. The quantification limits (LOQ) of the SBSE/LC-UV method ranged from 20 ng mL⁻¹ to 50 ng mL⁻¹, and the linear range was from LOQ to 500 ng mL⁻¹, with a determination coefficient higher than 0.99. The inter-day precision of the SBSE/LC-UV method presented a variation coefficient lower than 15%. The efficiency of the SBSE/LC-UV method was proved by analysis of plasma samples from elderly depressed patients.     

Comparison of four extraction methods for analysis of volatile hop‐derived aroma compounds in beer

The volatile organic compound profile in beer is derived from hops, malt, yeast, and interactions between the ingredients, making it very diverse and complex. Due to the range and diversity of the volatile organic compounds present, the choice of the extraction method is extremely important for optimal sensitivity and selectivity. This study compared four extraction methods for hop‐derived compounds in beer late hopped with Nelson Sauvin. Extraction capacity and variation were compared for headspace solid‐phase micro extraction, stir bar sorptive extraction, headspace sorptive extraction, and solvent‐assisted flavor evaporation. Generally, stir bar sorptive extraction was better suited for acids, headspace sorptive extraction for esters and aldehydes, while headspace solid‐phase microextraction was less sensitive overall, extracting 40% fewer compounds. Solvent‐assisted flavor evaporation with dichloromethane was not suitable for the extraction of hop‐derived volatile organic compounds in beer, as the profile was strongly skewed towards alcohols and acids. Overall, headspace sorptive extraction is found to be best suited, closely followed by stir bar sorptive extraction.     

Online desorption of molecularly imprinted stir bar sorptive extraction coupled to high performance liquid chromatography for the trace analysis of triazines in rice

Based on a special homemade interface, the molecularly imprinted stir bar sorptive extraction was coupled to high performance liquid chromatography for the online desorption and analysis. During desorption, the analytes desorbed from stir bar were delivered to a sample loop and then was introduced into liquid chromatography for further analysis. The online desorption and introduction processes were real‐time monitored by the ultraviolet detector of the liquid chromatography system. In this way, the method sensitivity and reproducibility was improved for the introduction timing of the desorption solvent with greatest concentration of the target analytes was accurately controlled. To demonstrate the feasibility of the method, terbuthylazine imprinted stir bar was synthesized and used for the analysis of nine triazines in rice. Under the optimized conditions, limits of detection of 0.02–0.11 μg/L and precision within 4.3–7.2% were achieved. The new method was compared with other two traditional offline desorption procedures, i.e. ultrasonic‐assisted desorption and static thermal desorption. The comparison results showed that the proposed method is accurate, precise, fast, and suitable for the trace analysis of complex samples.     

Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography‐mass spectrometry

Stir bar sorptive extraction is a powerful technique for the extraction and analysis of organic compounds in aqueous matrices. Carbonyl compounds are ubiquitous components in rainwater, however, it is a major challenge to accurately identify and sensitively quantify carbonyls from rainwater due to the complex matrix. A stir bar sorptive extraction technique was developed to efficiently extract carbonyls from aqueous samples following chemical derivatization by O‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine hydrochloride. Several commercial stir bars in two sizes were used to simultaneously measure 29 carbonyls in aqueous samples with detection by gas chromatography with mass spectrometry. A 100 mL aqueous sample was extracted by stir bars and the analytes on stir bars were desorbed into a 2 mL solvent solution in an ultrasonic bath. The preconcentration Coefficient for different carbonyls varied between 30 and 45 times. The limits of detection of stir bar sorptive extraction with gas chromatography mass spectrometry for carbonyls (10–30 ng/L) were improved by ten times compared with other methods such as gas chromatography with electron capture detection and stir bar sorptive extraction with high‐performance liquid chromatography and mass spectrometry. The technique was used to determine carbonyls in rainwater samples collected in York, UK, and 20 carbonyl species were quantified including glyoxal, methylglyoxal, isobutenal, 2‐hydroxy ethanal.