Gas Chromatography-nitrogen Phosphorous Detection Research Articles

Magnetic Poly(Amidoamine) Dendrimer for the Dispersive Solid Phase Extraction of Nitrophenols from Environmental Water Samples.

A fast and simple dispersive solid phase extraction method is described for nitrophenols determination in water samples by using gas chromatography-nitrogen phosphorous detector. Firstly, the Poly(amidoamine) grafted Fe3O4 magnetic nanoparticles were synthesized in different generations by successive addition of butyl acrylate and ethylenediamine. After characterization, the prepared dendrimer was utilized as an adsorbent for magnetic solid phase extraction of 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol to benefit large number of surface amine interaction sites. The effects of the different parameters influencing the sample preparation efficiency were investigated. The proposed method showed linearity in the ranges of 0.04-700 and 0.05-700µg/dm3 for nitrophenols. The obtained limits of detection and quantification under optimized conditions were 0.01-0.02 and 0.04-0.05µg/dm3, respectively. The relative standard deviations (n = 5) were less than 3.8% (at 10µg/dm3). Moreover, the calculated enrichment factors were above 200. In addition, the relative recoveries for a spiked river water sample were satisfactory.

Detection of phosphine in abdominal cavity material of woman dead body and ingesta of cow using Gas Chromatography-Nitrogen Phosphorous Detector technique (GC-NPD)

Detection of phosphine (poison) in unusual specimens (i.e abdominal cavity material of putrefied woman body) as well as in Ingesta of a cow using GC-NPD. Introduction: aluminium and Zinc Phosphides are commonly used as insecticides and rodenticides respectively. In Pakistan, these poisons are major contributors for homicidal and suicidal deaths because it is cheap and easily available. Phosphine is a gas liberated from Aluminium and Zinc Phosphides, in a reaction with acid. We report two cases of phosphine detection in such complex matrices. Case 1. A decapitated putrefied body of a woman was found whose legs and arms were not present. Internal organs including heart, lungs and kidneys were also eaten by animals. Abdominal cavity material was sent for forensic toxicological analysis in author's laboratory. Chances for detection of phosphine gas were very low, as specimen was highly decomposed and putrefied. Case 2. A Cow was found dead in the house of owner with no previous history of any disease. Ingesta of the Cow was submitted to author's laboratory with no pathological information by the veterinary doctor. Ingesta is also considered as a very complex matrix for toxicological analysis. Presumptive testing of phosphine was performed on abdominal cavity material and Ingesta with silver nitrate strip using Conway micro diffusion cell colorimetric technique. Confirmation was performed on Gas Chromatography-Nitrogen phosphorous detector with PLOT column. 10 mL samples of both abdominal cavity material and Ingesta were taken in separate headspace vials. Small amount of Zinc dust was added along with 2 mL of 6N sulphuric acid. Vials were then crimped and heated at 70 °C in oven for 30 minutes. 0.5 mL sample from headspace was manually injected in GC-NPD. Phosphine was detected in abdominal cavity material of woman and ingesta of cow. Total run time of the method is only 2 minutes. Peak of the phosphine was observed at 1.2 min retention time. Although there was less probability of phosphine gas detection from these specimens however analysis was attempted and results were found positive for phosphine. There is very less data available for the detection of poisons on putrefied specimens. Detection of phosphine, in matrices like exhumed specimens, putrefied parts or Ingesta of animals is a bit-challenging task for Forensic Toxicologists due to its tendency to escape from decomposed samples. In such cases, analysis must be attempted for the provision of justice. Phosphine is a very small molecule, but it can still be detected in abdominal cavity material of a putrefied body and Ingesta. There is also a strong need to regularize the sale, availability and purchase of Aluminum or Zinc Phosphide.

Quantitative analysis of phosphine in variety of biological samples from two cases of fatal poisoning

To highlight the importance of confirmation and quantitation of phosphine in variety of biological specimens using gas chromatography coupled with nitrogen phosphorus detector. Phosphine, a highly poisonous gas is liberated when aluminium or zinc phosphide come in contact with acid. These phosphides are commonly encountered in poisoning cases received in the author's laboratory. After reaction of phosphide with acid in the stomach, the formed gas is rapidly absorbed into blood from where it is distributed through out the body. Therefore, it is important to test multiple specimens for confirmation and quantitation of phosphine because of its rapid distribution throughout the body. Case 1. A 22-year-old male was allegedly poisoned due to conflict over money. He was taken to nearby hospital but he could not survive and died within three hours of incident. There was no significant finding in postmortem report. Stomach contents and liver were processed for toxicological analysis. Case 2. A 23-year-old female attempted suicide by ingesting poisonous pills due to marital conflicts. She was brought to hospital where she got treatment accordingly. Her blood, urine and gastric lavage samples were submitted to author's laboratory for identification of poison. Presumptive testing of phosphine using silver nitrate strips was performed on stomach contents in case 1 and gastric lavage in case 2. Confirmation and quantitation for phosphine was performed on Gas Chromatography-Nitrogen phosphorous detector with PLOT column. Specimens from both cases (10 mL) were taken in headspace vial. Small amount of Zinc dust was added along with 2 mL of 6 N sulphuric acid. Vials were then crimped and heated at 70 °C in oven for 30 minutes. 0.5 mL sample from headspace was then manually injected in GC-NPD. Total run time of the method is 2 min. Calibrators (10–500 ng/mL) were prepared by serial dilution and run concurrently in order to estimate the concentration of phosphine in submitted samples. All analyzed specimens from both cases were found positive for phosphine. Stomach contents and liver from case 1 contained 264 and 30 ng/mL phosphine respectively. Blood, urine and gastric lavage in case 2 were found to contain 21, 5 and 268 ng/mL phosphine respectively. Although manual injection may produce large variation in quantitation but it is still useful to get an estimate of phosphine concentration in biological samples. Detection of phosphine in stomach contents and gastric lavage in significant amount supports oral intake of phosphine by the victims. Furthermore, presence of phosphine in blood and liver indicates its systemic distribution while phosphine in urine demonstrates its excretion pathway. Phosphine is a deadly poison that should be analyzed at earliest because it has tendency to escape from biological specimens. This also emphasizes the availability of sensitive method for rapid identification of phosphine from multiple biological specimens.

Lowland tapir exposure to pesticides and metals in the Brazilian Cerrado

Abstract Context The Cerrado is a Global Biodiversity Hotspot as well as Brazil’s main frontier for large-scale agriculture and livestock production, making it one of the most threatened biomes in the country. Brazil is one of the biggest consumers of pesticides in the world and allows the use of chemicals that are banned in many other countries due to their adverse health effects in a wide range of species, including humans. Aims This study aimed to assess pesticide and metal exposure of the lowland tapir – a threatened, large herbivorous mammal – to support future studies of the role of these chemicals in tapir health, survivorship, and population viability. Methods Foot pad, proboscis, stomach contents, liver, bone, and nail samples were obtained from tapir carcasses found along highways (n = 87). (i) Atomic absorption spectrophotometry (AAS) was used to detect metals in bone, nail and liver tissue; (ii) gas chromatography – nitrogen phosphorous detector (GC-NPD) to detect organophosphates in liver and skin; and (iii) high performance liquid chromatography – ultraviolet (HPLC-UV) to detect pyrethroids and carbamates in stomach contents. Key results Two carbamates (aldicarb and carbaryl), three organophosphates (diazinon, malathion, and mevinphos), two pyrethroids (deltamethrin and permethrin), and two toxic metals (cadmium and lead) were detected in different tapir tissue samples, some at concentrations high enough to cause adverse health effects. In 90% of roadkill tapirs that were subjected to a full post-mortem examination (n = 25), macroscopic alterations of liver and/or kidney tissue were observed. Conclusions This study provides the first report to date of the detection of pesticides and metals in lowland tapirs. Implications Some of the reported pesticide concentrations exceed environmental safety thresholds. Consequently, results from this study raise concerns over potential adverse health effects in tapirs that could lead to population level impacts, thus requiring further investigation.

Combination of dispersive solid phase extraction with solidification organic drop-dispersive liquid-liquid microextraction based on deep eutectic solvent for extraction of organophosphorous pesticides from edible oil samples.

A dispersive solid phase extraction method was combined with deep eutectic solvent-based solidification of floating organic drop-dispersive liquid-liquid microextraction and used for the extraction/preconcentration of some organophosphorus pesticides residues from edible oil samples. The extracted analytes were quantified with gas chromatography-nitrogen phosphorous detector. In this procedure, the sample lipids are saponified with a sodium hydroxide solution and then the analytes are adsorbed onto a primary secondary amine sorbent. After that the analytes are desorbed with acetone as an elution/dispersive solvent and mixed with choline chloride: 3,3-dimethyl butyric acid deep eutectic solvent and the mixture is rapidly dispersed into deionized water. Then, the obtained cloudy solution is centrifuged and placed into an ice bath. The extraction solvent is solidified on the top of the solution. Finally, it is removed and dissolved in acetonitrile, and 1 µL of the solution is injected into the separation system. Validation of the method showed that limits of detection and quantification were in the ranges of 0.06-0.24 and 0.20-0.56 ng mL-1, respectively. Enrichment factors and extraction recoveries of the analytes ranged from 170-192 and 68-77%, respectively. The method had an acceptable precision with relative standard deviations less than ≤9.2% for intra- (n=6) and inter-day (n=6) precisions at four concentrations (3, 10, 50, and 250 ng mL-1, each analyte). Finally the method was used for determination of the analytes in five edible oil samples.

Analysis of \u03b1-dicarbonyl compounds and volatiles formed in Maillard reaction model systems

In this study, production of three α-dicarbonyl compounds (α-DCs) including glyoxal (GO), methylglyoxal (MGO), and diacetyl (DA) as well as volatile flavor compounds was analyzed using Maillard reaction (MR) model systems. A total of 16 model systems were assembled using four amino acids and four reducing sugars, and reactions were performed at 160 °C and pH 9. Determination of α-DCs was conducted using a gas chromatography/nitrogen phosphorous detector (GC-NPD) after derivatization and liquid-liquid extraction. α-DC levels in MR model systems were 5.92 to 39.10 μg/mL of GO, 3.66 to 151.88 μg/ml of MGO, and 1.10 to 6.12 μg/mL of DA. The highest concentration of total α-DCs was found in the fructose-threonine model system and the lowest concentration in the lactose-cysteine model system. Volatile flavor compounds were analyzed using solid-phase micro-extraction (SPME) followed by GC-mass spectrometry (GC-MS). Different volatile flavor compound profiles were identified in the different MR model systems. Higher concentrations of α-DCs and volatile flavor compounds were observed in monosaccharide-amino acid MR model systems compared with disaccharide-amino acid model systems.

Monitoring heavy metals, residual agricultural chemicals and sulfites in traditional herbal decoctions

BackgroundAsian traditional herbal preparations are frequently considered for the contamination with undeclared toxic or hazardous substances. The aim of this study was to determine the toxic heavy metals, pesticides and sulfur dioxide in decoctions that is a common form of final utilization in Korea.MethodsA total of 155 decoctions composed of multi-ingredient traditional herbs were randomly sampled from Seoul in Korea between 2013 and 2014. For each decoction, the concentrations of four heavy metals (arsenic, cadmium, lead and mercury), 33 pesticides and sulfur dioxide were analyzed using inductively coupled plasma mass spectrometry (ICP-MS), mercury analyzer, gas chromatography/nitrogen phosphorous detector (GC/NPD), gas chromatography/micro electron capture detector (GC/μECD), and Monier-Williams method respectively.ResultsOne hundred fifty-two of One hundred fifty-five decoctions (98.1%) contained one of three heavy metals (96.1% for As, 97.4% for Cd, and 90.3% for Pb, 0.0% for Hg). Their average concentrations (77.0 ± 79.7 ug/kg for As, 20.4 ± 23.7 ug/kg for Cd, and 68.8 ± 76.5 ug/kg for Pb) were approximately 20% of the maximum allowable limits of vegetable or ginseng beverage described in the Korean Food Standard Codex while their 95th percentile concentrations were below than the guideline for them. None of 33 pesticides was detected in 155 decoction samples, and only one sample showed over limit of detection for residual sulfites.ConclusionsThis study support that the contained status of toxic heavy metals, pesticides and sulfur dioxide in herbal decoctions are currently within safe level in Korea, and provide a reference data for the further studies focused on the safety herbal preparations.

Validation of analytical method for α‐dicarbonyl compounds using gas chromatography–nitrogen phosphorous detector and their levels in alcoholic beverages

SummaryThis study aimed to establish an analytical method for α‐dicarbonyl compounds (α‐DCs) including glyoxal, methylglyoxal and diacetyl, to determine the content of α‐DCs in 101 various alcoholic beverages using gas chromatography–nitrogen phosphorous detector (GC‐NPD) and to perform exposure assessment. The limit of detection and limit of quantification for α‐DCs were 0.05–0.22 and 0.15–0.70 μg g−1, respectively. The accuracy and precision were validated in five matrices. The raspberry fruit wine had the highest value at 139.74 μg g−1 total α‐DCs. The lowest α‐DC concentration among the beverages was detected in rice wine (Makgeolli) at 1.59 μg g−1. The levels of α‐DCs in various samples were detected as follows: 1.59–56.68 μg g−1 in rice wine (Makgeolli), 2.73–16.77 μg g−1 in beer, 8.22–139.74 μg g−1 in fruit wine and 8.17–91.56 μg g−1 in rice wine (Cheongju). The estimated daily intake of α‐DCs in the intake‐only group and population group was calculated as 4.22–97.94 μg kg−1 bw day−1 and 0.28–7.13 μg kg−1 bw day−1, respectively.

Extraction and preconcentration of triazine pesticides using rapid, simple, and disperser solventless microextraction technique followed by gas chromatography–nitrogen phosphorous detection

In this study, a simple, rapid, and efficient microextraction method followed by gas chromatography–nitrogen‐phosphorous detection has been applied for the extraction, preconcentration and determination of some triazine pesticides in edible oil samples. In this method, initially the oil sample is dissolved in hexane and then a few microliter of a less soluble organic solvent in hexane (extraction solvent) is added. The mixture is rapidly aspirated into a glass syringe and then is injected into a conical centrifuge tube for predetermined cycles to form a cloudy solution. Some experimental parameters that influence the extraction efficiency, such as type and volume of the extraction solvent, extraction numbers, and centrifuging rate and time are examined and optimized. Under optimum extraction conditions, the method showed low limits of detection and quantification between 0.02 to 0.09 and 0.07 to 0.30 μg/L, respectively. Extraction recoveries were in the range of 74–96%.Practical applications:This paper describes an analytical method that can be used by oil manufacturers for quality control purposes. A disperser solventless microextraction method and GC‐NPD were used to monitor triazine pesticides in different edible oils and propazine was found in corn oil.Triazine pesticides often contaminate the seeds and hence will be transferred into the oils during the extraction process. For trace determination of triazines in edible oil, 1 mL edible oil was diluted with 4 mL n‐hexane in conical tube and 40 µL DMSO was added. The mixture was rapidly aspirated into a 10‐mL glass syringe and then injected into the tube (4 times) to form a cloudy solution. The method showed low limits of detection and quantification between 0.02 to 0.09 and 0.07 to 0.30 µg/L, respectively. Extraction recoveries were in the range of 74–96%.

Three-dimensional graphene aerogel-supported iron oxide nanoparticles as an efficient adsorbent for magnetic solid phase extraction of organophosphorus pesticide residues in fruit juices followed by gas chromatographic determination

In this research, a magnetic three dimensional-graphene nanocomposite (3D-G-Fe3O4) was prepared, characterized and used as an effective nanoadsorbent in magnetic solid-phase extraction (MSPE) of eight organophosphorus pesticides (OPPs) from juice samples prior to gas chromatography-nitrogen phosphorous detection (GC-NPD). The properties and morphology of 3D-G-Fe3O4 were characterized by scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). The main experimental parameters affecting extraction recoveries including extraction time, amount of adsorbent, pH of sample solution, salt concentration and desorption conditions were carefully studied and optimized. The results showed wide linear concentration ranges with determination coefficients between 0.9973 and 0.9999. The limits of detection (S/N=3) of the method and limits of quantification (S/N=10) were from 1.2 to 5.1ngL−1 and 3.4–17.0ngL−1, respectively. The intra-day and inter-day RSDs were 2.6–5.1% and 3.5–6.9%, respectively. The method was successfully applied to the analysis of OPPs in fruit juices (apple, orange, grape, sour-cherry and apricot) with recoveries in range of 86.6–107.5%. The GC-NPD results were confirmed by gas chromatography–mass spectrometry (GC–MS). The results demonstrated that with combination of highly interconnected 3D network structure and magnetism property of adsorbent, 3D-G-Fe3O4 aerogel exhibited exceptional extraction ability towards the OPPs.

Sampling and Analytical Method for Alpha-Dicarbonyl Flavoring Compounds via Derivatization with o-Phenylenediamine and Analysis Using GC-NPD.

A novel methodology is described for the sampling and analysis of diacetyl, 2,3-pentanedione, 2,3-hexanedione, and 2,3-heptanedione. These analytes were collected on o-phenylenediamine-treated silica gel tubes and quantitatively recovered as the corresponding quinoxaline derivatives. After derivatization, the sorbent was desorbed in 3 mL of ethanol solvent and analyzed using gas chromatography/nitrogen-phosphorous detection (GC/NPD). The limits of detection (LOD) achieved for each analyte were determined to be in the range of 5–10 nanograms/sample. Evaluation of the on-tube derivatization procedure indicated that it is unaffected by humidities ranging from 20% to 80% and that the derivatization procedure was quantitative for analyte concentrations ranging from 0.1 μg to approximately 500 μg per sample. Storage stability studies indicated that the derivatives were stable for 30 days when stored at both ambient and refrigerated temperatures. Additional studies showed that the quinoxaline derivatives were quantitatively recovered when sampling up to a total volume of 72 L at a sampling rate of 50 cc/min. This method will be important to evaluate and monitor worker exposures in the food and flavoring industry. Samples can be collected over an 8-hour shift with up to 288 L total volume collected regardless of time, sampling rate, and/or the effects of humidity.

A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air-assisted liquid-liquid microextraction from human urine and plasma samples followed by gas chromatography-nitrogen phosphorous detection.

In present study, a simultaneous derivatization and air-assisted liquid-liquid microextraction method combined with gas chromatography-nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1-flouro-2,4-dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05-0.34 ng mL(-1) are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples.

An Efficient Screening Method for Detection of Toluene-based Inhalant Abuse in Urine by Gas Chromatography-Nitrogen Phosphorous Detector

An Efficient Screening Method for Detection of Toluene-based Inhalant Abuse in Urine by Gas Chromatography-Nitrogen Phosphorous Detector

GC/NPD와 GC/ECD를 이용한 잔류농약 정량 분석법으로써의 QuEChERS의 평가

The modified QuEChERS method was evaluated for rapid determination of pesticide residues in spinach by gas chromatography-nitrogen phosphorous detector (NPD) and electron capture detector (ECD). Fifty GC-amenable pesticides which were most frequently detected in monitoring were selected in the current study. Matrix-matched calibration was performed. The detector response for all pesticides was linear with determination coefficients higher than 0.995. LODs for most compounds ranged between 0.001 and 0.1 ug/g, and about 90% of the compounds had LODs of less than 0.05 ug/g. LOQs ranged from 0.001 to 0.32 ug/g, which were well below the MRLs permitted for most of pesticides. In the majority of cases, the recoveries (80-120%) and relative standard deviations (RSDs) (less than 20%) were within acceptable levels except for dichlorvos, propamocarb, chlorothalonil, dichlofluanid, cyhalothrin and fenvalerate. Also, this method which is applied to routine samples showed good results when comparing with traditional multi-residue method.

Microporous silica with nanolayer structure coated with renewable organic solvent film as a novel extracting phase: A combination of solid- and liquid-phase microextraction

A new method based on combination of solid- and liquid-phase microextraction was developed. For the first time, porous flower-like silica microstructures with nanometric layers were created on the surface of the stainless steel wire by a new facile hydrothermal process. The fiber, coated with a suitable organic solvent, was applied for microextraction of some organophosphorus pesticides from aqueous samples followed by gas chromatography-nitrogen phosphorous detection. Method detection limits were between 0.6 and 3ngL−1. Relative standard deviations for intra- and inter-day precision were 4.4–7.3% and 5.1–7.8%, respectively. Fiber-to-fiber reproducibility for five prepared fibers was 6.3–8.4%. Tap, river and waste water samples were analyzed for evaluation of the method in real sample analysis. Relative recoveries for spiked tap, river and waste water samples were in the range of 94–101%, 89–97% and 82–103%, respectively. In addition, the method was compared with two commercial solid-phase microextraction (SPME) fibers, single drop microextraction (SDME) and liquid-phase microextraction (LPME). The present method showed higher extraction efficiency as compared with SDME, LPME and commercial SPME fibers.

Method development for the analysis of organophosphate and pyrethroid insecticides at low parts per trillion levels in water

In the current study, organophosphate and pyrethroid insecticides including diazinon, chlorpyrifos, bifenthrin, fenpropathrin, permethrin, λ-cyhalothrin, cyfluthrin, cypermethrin, esfenvalerate and deltamethrin were analyzed in laboratory and field-collected water samples. Water samples were extracted and analyzed by gas chromatography/electron capture detector (GC/ECD) and gas chromatography/nitrogen–phosphorous detector (GC/NPD). Comparison of results from liquid–liquid extraction and subsequent normal phase solid-phase extraction cleanup (LLE–NPSPE), and reversed phase solid-phase extraction (RPSPE) showed that LLE–NPSPE was the better choice to extract trace amounts of pesticides from water. Pesticide recoveries from four spiked water samples using LLE–NPSPE ranged from 63.2 to 148.8% at four spiking concentrations. Method detection limits were 0.72–1.69 ng/L using four different water sources. The stability of the target pesticides in lake water was investigated at 4 °C for 1 h, 1 d, 4 d, and 7 d under three conditions: (1) water samples only; (2) with 20 mL hexane used as a keeper solvent; and (3) with acidification to pH 2 with HCl. Results showed that water storage without treatment resulted in slow degradation of some pesticides with storage time, storage using water acidification led to significant degradation and loss of diazinon and chlorpyrifos, while water storage with hexane as a keeper solvent showed good stability for all of the target pesticides over the 7 d storage period.

Adult respiratory distress syndrome in human organophosphate poisoning cases

Adult respiratory distress syndrome (ARDS) is a clinical syndrome which occurs due to various direct or indirect noxious agents and pyhsical mechanisms. One of the etiological factors is ingested chemicals (e.g. paraquat, ethylene glycol). The organophosphorous (OP) insecticides are the most toxic and frequently encountered chemicals that produce poisoning in humans. Studies were undertaken to investigate whether OP insecticides may produce ARDS. Fifteen autopsy cases due to suicidal OP insecticide poisoning were investigated. Toxicological analyses were performed with a gas chromatography-nitrogen phosphorous detector (GC-NPD). Methamidophos, dimefox and dichlorvos were the detected OP. Lungs were examined macroscopically. Two cases showed features compatible with ARDS in which the only cause of death was OP poisoning. Due to the severity of ARDS it is important to assess insecticidal exposure in an attempt to enhance survival patterns following OP poisoning in patients in order to initiate therapy.

Suitability of a Novel Circulating Cooling SPME for Analysis of Organophosphorous Pesticides in Tomatoes

The feasibility of circulating cooling-solid phase microextraction (CC-SPME) combined with gas chromatography-nitrogen phosphorous detector (GC-NPD) for the determination of five organophosphorous pesticides (OPPs) in tomato samples is evaluated. By heating the sample while cooling the fiber coating, the developed method provides better performance in terms of sensitivity, linearity and recovery than that of traditional headspace-solid phase microextraction (HS-SPME). The extraction capacities of activated carbon fiber (ACF) and three commercially available fibers were compared. ACF is found to be the most suitable fiber for the analysis of OPPs in tomatoes. The main factors affecting the CC-SPME process such as adsorption time, adsorption temperature and ionic strength were investigated and optimized. The matrix effect was evaluated, and concluded that addition of water is required to reduce the matrix effect. Good linearity (R2 > 0.992) is observed in the 1–200 ng g−1 concentration range with satisfactory RSD (%) values of 5.6–8.5%. The limits of detection obtained using the proposed method range from 0.2 to 0.5 ng g−1, and the recoveries for CC-SPME are in the range of 82.5–90.0% with RSDs lower than 8.7%. Experimental results confirm the usefulness of the proposed method for the analysis of OPPs in tomato samples.

Determination of N-vinyl-2-pyrrolidone and N-methyl-2-pyrrolidone in drugs using polypyrrole-based headspace solid-phase microextraction and gas chromatography–nitrogen-phosphorous detection

A headspace solid-phase microextraction and gas chromatography–nitrogen-phosphorous detection (HS-SPME–GC–NPD) method using polypyrrole (PPy) fibers has been introduced to determine two derivatives of pyrrolidone; N-vinyl-2-pyrrolidone (NVP) and N-methyl-2-pyrrolidone (NMP). Two types of PPy fibers, prepared using organic and aqueous media, were compared in terms of extraction efficiency and thermal stability. It was found that PPy film prepared using organic medium (i.e. acetonitrile) had higher extraction efficiency and more thermal stability compared to the film prepared in aqueous medium. To enhance the sensitivity of HS-SPME, the effects of pH, ionic strength, extraction time, extraction temperature and the headspace volume on the extraction efficiency were optimized. Using the results of this research, high sensitivity and selectivity had been achieved due to the combination of the high extraction efficiency of PPy film prepared in organic medium and the high sensitivity and selectivity of nitrogen-phosphorous detection. Linear range of the analytes was found to be between 1.0 and 1000 μg L −1 with regression coefficients ( R 2) of 0.998 and 0.997 for NVP and NMP, consequently. Limits of detection (LODs) were 0.074 and 0.081 μg L −1 for NVP and NMP, respectively. Relative standard deviation (R.S.D.) for five replications of analyses was found to be less than 6.0%. In real samples the mean recoveries were 94.81% and 94.15% for NVP and NMP, respectively. The results demonstrated the suitability of the HS-SPME technique for analyzing NVP and NMP in two different pharmaceutical matrices. In addition, the method was used for simultaneous detection of NVP, 2-pyrrolidone (2-Pyr), γ-butyrolactone (GBL) and ethanolamine (EA) compounds.

Solid phase microextraction applied to the analysis of organophosphorus insecticides in fruits

Trace amounts of organophosphorus pesticides (OPs) were determined in various fruits by headspace solid phase microextraction (HS-SPME) and gas chromatography–nitrogen phosphorous detection (GC-NPD). Sampling from the headspace enhanced method selectivity, whereas at the same time improved fiber life time and method sensitivity. Diazinon, parathion, methyl parathion, malathion and fenithrothion were determined in various fruits: more than 150 samples of 21 types of fruits were studied. SPME-GC-NPD provided a useful and very efficient analytical tool: method linearity ranged from 1.2 to 700 ng/ml. Limits of detection (LODs) and quantitation (LOQs) ranged from 0.03 to 3 ng/ml and 0.12 to 10 ng/ml respectively, values well below the residue limits set by the EU. Less than 2% of the samples were found positive containing amounts higher than the EU limits. The effect of fruit peeling and washing was also investigated.