Determination Of Chemical Agents Research Articles

Application of a PLA/PBAT/Graphite sensor obtained by electrospinning on determination of 2,4,6-trichlorophenol

ABSTRACT The widespread use of pesticides requires effective detection and quantification tools to improve monitoring of environmental quality. Electrochemical sensors offer a fast and sensitive response, and can also be optimized by combining several constituents and techniques, including biodegradable materials, being useful in the determination of chemical agents from environmental samples. Here, we produced a polymer-based sensor for 2,4,6-trichlorophenol determination, through electrospinning of poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blend with graphite. The graphite-containing fibres were thermally treated and wetted in mineral oil, thus forming a paste, used as an electrode in the electrochemical sensor. The thermal analysis indicated a disorganization of the polymeric chains between the aromatic carbon chain of the PBAT polymer, resulting in a material with low enthalpy, lower crystallinity and greater thermal degradability after insertion of graphite in polymeric fibres. NIR spectra revealed changes related to the carbonyls of the polymeric ester groups. Cyclic voltammetry and square wave voltammetry techniques were applied to study the electrochemical behaviour of developed sensor. The thermal treatment of graphite-containing fibres increased the adhesion surface in which occurs the adsorption of the analyte on the electrode, which improved the peak current in the electrochemical tests. The PLA/PBAT/Graphite sensor applied to determination of 2,4,6-TCP presented the detection and quantification limits of 7.84 × 10−8 mol L−1 (0.0155 mg L−1) and 2.36 × 10−7 mol L−1 (0.0466 mg L−1) with a linearity response of 1.00 × 10−7 mol L−1 and 2.00 × 10−6 mol L−1 with correlation coefficient of 0.993 (r 2).

Pentane-1-ol and its isomers. Determination in workplace air with GC with Flame Ionization Detector (GC-FID)

Amyl alcohol (pentan-1-ol) – C5H12O or C5H11OH – is an organic chemical compound from the group of saturated monohydric aliphatic alcohols. There are 8 known isomers of pentanol: pentan-1-ol (CAS:71-41-0), pentan-2-ol (CAS: 6032-29-7), pentan-3-ol (CAS: 584-02-1), 2-metylobutan-1-ol (CAS: 137-32-6), 3-metylobutan-1-ol (CAS: 123-51-3), 2-metylobutan-2-ol (CAS: 75-85-4), 3-metylobutan-2-ol (CAS: 598-75-4) i 2,2-dimetylopropan-1-ol (CAS: 75-84-3). All of them are commonly referred to as amyl alcohols. Pentanol isomers exhibit chemical properties characteristic of aliphatic alcohols, they are obtained by hydration of pentene isomers, hydrolysis of chloropentanes or by reaction of butene and carbon monoxide isomers. They are used as solvents for fats, resins and waxes. Pentan-1-ol is absorbed into the human body through the respiratory tract, skin, gastrointestinal tract. Symptoms of acute intoxication are usually tearing eyes, redness of the conjunctiva, irritation of the mucous membrane of the nose and throat. In higher concentrations it may cause headache, dizziness, nausea, vomiting, diarrhea, delirium, disturbances of consciousness, coma. Arrhythmia and respiratory disorders may cause redness and burning, as well as symptoms such as inhalation poisoning, eye contamination with liquid substance causes pain, burning of the eyes, redness of the conjunctiva, with the risk of long-lasting and permanent changes. Repeated skin contact with the liquid substance may cause its drying and inflammation. It is suggested that long-term exposure of the skin to the substance at high concentration may lead to changes in the nervous system. The aim of this study was to develop and validate a sensitive method of determining 8 pentan-1-ol isomers in the working environment in the range from 1/10 to 2 of the MAC values. The gas chromatography method with a flame ionization detector (GC-FID) was used to determine pentan-1-ol and its isomers. It was decided to develop a method that ensures the determination of at least 1/10 of the MAC values. Further considerations of the possibility of determining this substance in the air are based on previously developed analytical methods. The use of the HP-5 capillary column enables the selective determination of pentan-1-ol in the presence of carbon disulphide, methanol and other co-existing compounds. The detector's response to the analyzed pentan-1-ol concentrations is linear (r2 = 0.9998) in the concentration range 10–2000 μg/ml, which corresponds to the range of 1–200 mg/m3 (0.01–2 of the MAC values) for a 10-L air sample. The limit of quantification (LOQ) of this method is 0.026 μg/ml. The developed method is characterized by good precision and accuracy and meets the requirements of Standard No. PN-EN 482 for procedures regarding the determination of chemical agents. The developed method for determining pentan-1-ol has been recorded in the form of an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

But-2-enal. Determination in workplace air

But-2-enal (crotonaldehyde) is a colourless liquid with an unpleasant suffocating odour. But-2-enal occurs naturally in food. It is mainly used for the production of sorbic acid, a food preservative. But-2-enal is a very toxic, highly irritating and allergenic substance – it is suspected of causing genetic defects. The aim of the study was to develop a method for determination of but-2-enal, which will enable determination of concentrations of this substance in the workplace air in the range from 1/10 to 2 MAC values. The tests were performed using a liquid chromatograph (HPLC) with a diode array detector (DAD), equipped with an Ultra C18 column (250 x 4.6 mm; 5 μm). The method consists in retaining the but-2-enal on a silica gel coated with 2,4-dinitrophenylhydrazine. The sample is extracted with acetonitrile and analyzed by HPLC. Validation of the method was carried out in accordance with the requirements of the European standard EN 482. The measuring range of the method is from 0.1 to 2 mg/m3 for a 12 l sample of air. The following validation parameters were obtained: limit of detection: 1.26 ng/ml (0.21 μg/m3), limit of quantification: 3.77 ng/ml (0.63 μg/m3), the overall accuracy of the method: 5.08%, expanded uncertainty: 22%. The developed analytical method enables selective determination of but-2-enal in workplace air at concentrations ranging from 0.1 mg/m3, i.e. from 1/10 of the MAC value in the presence of co-occurring substances. The method is characterized by good precision and accuracy and meets the requirements of the European standard PN-EN 482 for procedures for determination of chemical agents. The developed method of determining but-2-enal has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Chloroethene. Determining in workplace air with gas chromatography – mass spectrometry

Chloroethene (vinyl chloride) is a large volume compound, which does not occur naturally in nature. It is obtained synthetically only. About 98% of all vinyl chloride production is used to produce polyvinyl chloride (PVC) and copolymers. Exposure to this compound occurs during the synthesis and polymerization, plastification and processing of polymers and copolymers. Vinyl chloride processing takes place in industries of plastics, footwear, rubber, pharmaceutical and other. In Poland, the total number of people exposed occupationally to this compound according to the data of the Chief Sanitary Inspectorate of 2015 is over 1300 people. Exposure of people to vinyl chloride can occur by inhalation, with water and food. Workers chronically exposed to high levels of vinyl chloride suffered from disease symptoms called vinyl chloride syndrome or disease, including headache and dizziness, blurred vision, fatigue, lack of appetite, nausea, insomnia, shortness of breath, stomach pain, pain in liver/spleen area. Clinical trials include rheumatoid changes of the skin, allergic dermatitis, acroosteolysis, peripheral polineuropathy, neurological disorders, and fibrosis of a liver, enlargement of spleen and liver, disturbances of porphyrins. Vinyl chloride has mutagenic/genotoxic properties. Vinyl chloride has been classified as a carcinogen by the International Agency for Research on Cancer, IARC (Group 1) and the European Union (Category 1.A). The aim of this study was to develop and validate a sensitive method for determining concentrations of vinyl chloride in workplace air the range from 1/10 to 2 MAC values. The study was performed using a gas chromatograph with mass spectrometry. The aim was to develop a method ensuring adequate determination of at least 1/10 NDS. Further considerations of the possibility of determining this substance in the air are based on previously developed analytical methods. The use of the capillary INNOVAX column enables a selective determination of vinyl chloride in the presence of toluene, acetone and other co-existing compounds. The detector's response to the analyzed chloroethene concentration was linear (r2 = 0.9972) in the concentration range 1–26 μg / ml, which corresponded to the range of 0.20–5.2 mg/m3 (0.08–2 MAC value) for the a 5-L air sample. The limit of quantification (LOQ) of this method is 0.07 μg/ml. The developed method is precise, accurate and it meets the requirements of the European Standard No. PN-EN 482+A1: 2016 for procedures regarding the determination of chemical agents. The developed method for determining vinyl chloride has been recorded as an analytical procedure (see appendix).