Analysis for fungicides in paint

Summary Simple methods have been developed for the determination of copper and 8-hydroxyquinoline in paint films. Copper is separated from 8-hydroxy-quinoline by precipitation as copper sulphide and is determined photometrically either by means of diphenylcarbazone (0.1–1g Cu/ml) or benzoin oxime (1 to 10 g Cu/ml). 8-Hydroxyquinoline is determined by measuring the optical density in the ultraviolet region.

---

Zusammenfassung Einfache Verfahren zur Bestimmung von Kupfer und 8-Hydroxychinolin in Anstrichfilmen werden beschrieben. Kupfer wird als Sulfid abgetrennt und photometrisch mit Diphenylcarbazon (0,1–1g Cu/ml) oder Benzoinoxim (1–10g Cu/ml) bestimmt. 8-Hydroxychinolin wird durch Messung der UV-Absorption bestimmt.

---

---

Part III: Hoffmann, E., A. Saracz, and B. Bursztyn: Z. analyt. Chem. 208, 431 (1965).     

Chiral separation of agricultural fungicides

Fungicides are very important and diverse environmental and agricultural concern species. Their determination in commercial formulations or environmental matrices, requires highly efficient, selective and sensitive methods. A significant number of these chemicals are chiral with the activity residing usually in one of the enantiomers. The different toxicological and degradation behavior observed in many cases for fungicide enantiomers, results in the need to investigate them separately. For this purpose, separation techniques such as GC, HPLC, supercritical fluid chromatography (SFC) and CE have widely been employed although, at present, HPLC still dominates chromatographic chiral analysis of fungicides. This review covers the literature concerning the enantiomeric separation of fungicides usually employed in agriculture grouping the chiral separation methodologies developed for their analysis in environmental, biological, and food samples.     

Analysis for fungicides in paint

Summary A simple procedure for the determination of salicylanilide and paratoluene sulphonamide in paints has been worked out. Salicylanilide is determined by ethanol extraction and subsequent measuring of the UV-absorption spectrum, and also by determining the nitrogen content according to Kjeldahl. For the determination of para-toluene sulphonamide three different methods are employed, viz., the Kjeldahl determination of the nitrogen content, the determination of the sulphur content by burning the sample in an oxygen flask and subsequent determination of sulphate, and also by measuring the UV-absorption spectrum, the last method being only a semi-quantitative check.

---

Zusammenfassung Ein einfaches Verfahren zur Bestimmung von Salicylanilid und p-Toluolsulfonamid in Anstrichfarben wird beschrieben. Die Salicylanilidbestimmung erfolgt durch Äthanolextraktion und anschließende Messung des UV-Absorptionsspektrums sowie durch Stickstoffbestimmung nach Kjeldahl. Zur Bestimmung von p-Toluolsulfonamid dient ebenfalls die Stickstoffbestimmung nach Kjeldahl, sowie die Schwefelbestimmung durch Verbrennung in Sauerstoff mit anschließender Sulfatbestimmung und auch die UV-Absorptionsspektrometrie, letztere jedoch nur als halb quantitative Kontrollmethode.

---

---

Part II: Hoffmann, E., B. Bursztyn, and A. Saracz: Z. analyt. Chem. 207, 432 (1965).     

Behavior of nitrogenated fungicides upon gamma-irradiation

Three nitrogenated fungicides (Bayfidan, Bayleton and Baycor) were irradiated with -rays from a⁶⁰Co source with the products being analyzed by high resolution gas chromatography (HRGC). Within the dose range studied (5 to 640 kGy), all three compounds were found to be stable.     

A thermogravimetric study of some dithiocarbamate fungicides

A series of dithiocarbamate-based fungicides was investigated by thermogravimetry and differential thermal analysis. The differences in the thermal decompositions of various dithiocarbamate derivatives were traced to differences in their structures. The characteristic sections of the thermogravimetric curves of the group of fungicides based on ethylene-bis-dithiocarbamates of bivalent metal ions were established. On the basis of the differences in the shapes of the T and TG curves some fungicides can be identified. A group-method was developed for the quantitative determination of the active ingredient in fungicides based on the ethylene-bis-dithiocarbamates of bivalent metals, the characteristic shape of the TG curve being utilized for analytical purposes.

---

Zusammenfassung Fungizide auf Dithiocarbamat-Basis wurden thermogravimetrisch und mit Hilfe der Differentialthermoanalyse untersucht. Unterschiede in der thermischen Zersetzung konnten mit den entsprechenden Strukturen in Zusammenhang gebracht werden. Die charakteristischen Bereiche der TG Kurven von Fungizid-Gruppen, basiert auf Äthylen-bis-dithiocarbamate zweiwertiger Metalle, wurden ermittelt. Aufgrund der Unterschiede in den TG und T Kurven lassen sich verschiedene Fungizide identifizieren. Eine Methode zur Bestimmung der aktiven Gruppen von Äthylen-bis-dithiocarbamate zweiwertiger Metalle enthaltenden Fungiziden wurde unter Berücksichtigung der charakteristischen Form der TG Kurve ausgearbeitet.

---

Résumé Etude d'une série de fongicides à base de dithiocarbamate par thermogravimétrie et analyse thermique différentielle. On a trouvé une relation entre la structure de divers dithiocarbamates et leurs différences de comportement thermique. On a établi les parties caractéristiques des courbes thermogravimétriques du groupe des fongicides à base d'éthylène-bis-dithiocarbamates d'ions métalliques bivalents. Plusieurs fongicides peuvent être identifiés d'après la forme différente des courbes T et TG. On a élaboré une méthode de dosage de la partie active des fongicides à base d'éthylène-bis-dithiocarbamate de métaux bivalents où l'on utilise à des fins analitiques la forme caractéristique de la courbe TG.

---

. . . . , .

     

Analysis of post-harvest fungicides by micellar electrokinetic chromatography

A method based on solid-phase extraction (SPE) and micellar electrokinetic chromatography (MEKC) was developed for the simultaneous determination of carbendazim, imazalil, methylthiophanate, O-phenylphenol, prochloraz, procimidone, thiabendazole and triadimefon residues in grape, lettuce, orange and tomato. Selectivity and resolution were studied changing the pH and the concentration of the buffer, the type and concentration of surfactant and the methanol content in the mobile phase. A buffer consisting of 4 mM borate with 75 mM sodium cholate (pH 9.2) gave the best results. The recoveries of the fungicides in spiked fruit and vegetable samples ranged from 30 to 105%, and the limits of detection were between 0.1 and 1 mg kg(-1). The reproducibility and repeatability of the combination of SPE pretreatment and MEKC were good for all the compounds, except for imazalil and O-phenylphenol in oranges, due to some matrix compounds interfering with the separation. The method was applied to post harvest treated samples, and the fungicides were sometimes detected at concentration levels lower than maximum residue limits (MRLs).     

Hollow fiber-liquid-phase microextraction of fungicides from orange juices

Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500 μL of 840 mM NaOH was added to 3 mL of orange juice in order to compensate the acidity of the samples and to adjust pH into the alkaline region. Analytes were extracted in their neutral state through a supported liquid membrane (SLM) of 2-octanone into 20 μL of a stagnant aqueous solution of 10 mM HCl inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to analysis. Capillary electrophoresis (CE) was used during the optimization of the extraction procedure. Working under the optimized extraction conditions, LPME effectively extracted the analytes from different orange juices, regardless of different pH or solid material (pulp) present in the sample, with recoveries that ranged between 17.0 and 33.7%. The analytical performance of the method was evaluated by liquid chromatography coupled with mass spectrometry (LC/MS). This technique provided better sensitivity than CE and permitted the detection below the μg L⁻¹ level. The relative standard deviations of the recoveries (RSDs) ranged between 3.4 and 10.6%, which are acceptable values for a manual microextraction technique without any previous sample treatment, using a home-built equipment and working under non-equilibrium conditions (30 min extraction). Linearity was obtained in the range 0.1–10.0 μg L⁻¹, with r = 0.999 and 0.998 for TBZ and IMZ, respectively. Limits of detection were below 0.1 μg L⁻¹ and are consistent with the maximum residue levels permitted for pesticides in drinking water, which is the most restrictive regulation applicable for these kinds of samples. It has been demonstrated the suitability of three-phase LPME for the extraction of pesticides from citrus juices, suppressing any pretreatment step such as filtration or removal of the solid material from the sample, that may potentially involve a loss of analyte.     

Fungicidal and bactericidal activity of metal diethyldithiocarbamate fungicides

Copper diethyldithiocarbamate, cadmium diethyldithiocarbamate, lead diethyldithiocarbamate, nickel diethyldithiocarbamate and zinc diethyldithiocarbamate have been synthesized. They have been characterized using TG, DTA, IR spectroscopy, X-ray and atomic absorption spectrophotometry. The thermal conversion of the compounds is 54.36–88% at 1000°C. Their solubility in sodium hydroxide, mineral acids, organic solvents, distilled water and salts solution has been measured. Fungicidal activity of the dithiocarbamates has been tested by well or cup diffusion method using five fungi species. Their activity has also been tested by broth dilution method using six bacterial species. Minimum Inhibitory Concentration (bactericidal) is 6.25–25.00 μg mL⁻¹.     

恶霉灵为活性组分的聚合杀菌剂的合成

由3－羟基－5－甲基异恶唑（恶霉灵）与甲苯1，4－二异氰酸酯合成了3－（ 3′－异氰酸酯基－4′－甲基苯胺基羰基）氧基－5－甲基异恶唑，以苯乙烯－马 来酸酐的交替共聚物为化学载体，经乙二胺搭桥合成了以恶霉灵为活性组分的聚合 杀菌剂。用IR光谱，^1H NMR、质谱和元素分析等表征了化学结构，讨论了影响反 应的因素。     

GLC multiresidue analysis of postharvest fungicides in citrus fruit

Summary A simple GLC multiresidue method for the analysis of fenpropimorph, thiabendazole, imazalil, propiconazole and prochloraz residues in citrus fruit, with a limit of detection of 0.1 ppm, is reported.The fungicides are extracted with hexane: ethyl acetate (90:10, v/v) after pH-adjustment of the fruit homogenate. The GLC-separation is carried out using a bonded phase, SE-54, fused silica capillary column and fungicides are determined with a nitrogen-phosphorus detector.Recovery was always higher than 80% with standard deviation equal or lower than 7%. The method is suitable to determine residues in citrus, whole fruit or peel, treated with these fungicides at usual concentrations to avoid citrus decay.

---

GLC-Verfahren zur Bestimmung mehrerer Fungicide in Citrusfrüchten nach der Ernte

     

Liquid chromatographic-mass spectrometric determination of post-harvest fungicides in citrus fruits

Liquid chromatography (LC)-atmospheric pressure ionisation (API)-mass spectrometry (MS) has been used to determine residues of five fungicides in oranges with a minimum sample cleanup. Atmospheric pressure chemical ionisation (APCI) and electrospray (ES) were compared and both gave similar results in terms of sensitivity and structural information. The main ions were [M+H]+ for carbendazim, imazalil, thiophanate methyl and thiabendazole, and [M+H-C4H9NHCO]+ for benomyl. Samples were extracted with sodium sulphate and ethyl acetate. Although benomyl and thiophanate methyl were transformed through the extraction procedure to carbendazim, the method showed good precision (<13%) and recovery (>70%), except for thiophanate methyl (50%), whilst also yielding limits of detection (<0.03 mg kg(-1)) that are adequate for the determination of the studied fungicides in oranges.     

Comparison of HILIC columns for residue analysis of dithiocarbamate fungicides

Selective determination of dithiocarbamate (DTC) fungicides is mainly performed by hydrophilic interaction liquid chromatography (HILIC). According to Crnogorac and Schwack, DTC analyses by HILIC only lead to meaningful results with a zwitterionic polymer-based hydrophilic interaction liquid chromatography (ZIC-pHILIC) column. Considering the limited availability of this special type of column and the importance of DTC residue analysis, several new HILIC columns were evaluated as alternatives to the ZIC-pHILIC column. Detection was carried out by ultraviolet light and by mass spectrometry (MS) on a single quadrupole mass spectrometer coupled to an electrospray ionization interface operating in negative mode. On nearly all tested columns, separation of dimethyldithiocarbamates, ethylenebis(dithiocarbamates), and propylenebis(dithiocarbamates) was achieved with ammonium acetate eluents (pH 6.8). However, due to ion suppression by the buffer and the limited alkaline pH stability, the tested silica-based columns were not suitable for the sensitive analysis of DTCs. The polymer-based iHILIC-Fusion was the only alternative that offered high MS sensitivity, when a buffer containing 15?mM aqueous ammonium hydroxide and 7.5?mM ammonium hydrogen carbonate (pH 9.8) was used, but the separation of the three DTC subclasses was poor. Thus, considering both selectivity and sensitivity, the originally proposed polymer-based ZIC-pHILIC column still outperformed all the tested newly available alternative HILIC columns.     

Design,synthesis and bioassay of the emerging photo-responsive fungicides

Precise and spatiotemporal control over the pesticide remains to be a challenge. More efficient controlled release systems (CRSs) have been developed to support the precise delivery of active ingredients. Herein, we incorporated the photoremovable protecting groups (PRPGs) into phenamacril (PHE) and obtained two photo-responsive fungicides of NV-PHE and DEACM-PHE. The 4,5-dimethoxy-o-nitrobenzyl (NV) or 7-diethylaminocoumarin (DEACM)-caged PHE could release the active molecule PHE after irradiation of UV light and blue light, respectively. Optical properties and in-vitro/vivo fungicidal activities of NV-PHE and DEACM-PHE demonstrated the feasibility for light controlled release of PHE. DEACM-PHE could release 98% PHE by illumination of blue light. The irradiated DEACM-PHE could preserve the similar bioactivity of PHE, and significantly improve the in-vitro/vivo fungicidal activities compared to the non-irradiated DEACM-PHE. The optical controlled release of PHE from DEACM-PHE enabled the precise and spatiotemporal delivery of PHE, diversifying the development of CRSs for pesticide, and providing environment-friendly agricultural applications with high pesticide efficiency.     

Design and synthesis of chitin synthase inhibitors as potent fungicides

Chitin is a structural component of fungal cell walls but is absent in vertebrates,mammals,and humans.Chitin synthase is thus an attractive molecular target for developing fungicides.Based on the structure of its donor substrate,UDP-N-acetyl-glucosamine,as well as the modelled structure of the bacterial chitin synthase NodC,we designed a novel scaffold which was then further optimized into a series of chitin synthase inhibitors.The most potent inhibitor,compound 13,exhibited high chitin synthase inhibitory activity with an IC_(50) value of 64.5 μmol/L All of the inhibitors exhibited antifungal activities against the growth of agriculturally-destructive fungi,Fusarium graminearum,Botrytis cinerea.and Colletotrichum lagenarium.This work presents a new scaffold which can be used for the development of novel fungicides.     

A quantitative solid-state Raman spectroscopic method for control of fungicides

A new analytical procedure using solid-state Raman spectroscopy within the THz-region for the quantitative determination of mixtures of different conformations of trifloxystrobin (EE, EZ, ZE and ZZ), tebuconazole (1), and propiconazole (2) as an effective method for the fungicide product quality monitoring programmes and control has been developed and validated. The obtained quantities were controlled independently by the validated hybrid HPLC electrospray ionization (ESI) tandem mass spectrometric (MS) and matrix-assisted laser desorption/ionization (MALDI) MS methods in the condensed phase. The quantitative dependences were obtained on the twenty binary mixtures of the analytes and were further tested on the three trade fungicide products, containing mixtures of trifloxystrobin-tebuconazole and trifloxystrobin-propiconazole, as an emissive concentrate or water soluble granules of the active ingredients. The present methods provided sufficient sensitivity as reflected by the metrologic quantities, evaluating the concentration limit of detection (LOD) and quantification (LOQ), linear limit (LL), measurement accuracy and precision, true quantity value, trueness of measurement and more.