QUANTITATIVE DETERMINATION OF 2,4-D IN PESTICIDES MONOSAN HERBI AND DMA-6

A rapid and reliable method for determination of active ingredient 2,4-D ((2,4-dichlorophenoxy)acetic acid) in the pesticide formulations Monosan herbi and DMA-6 is presented. The procedure utilizes high-performance liquid chromatography (HPLC) followed by UV diode array detection and two analytical columns with different stationary phases and dimensions. The better results for identification and quantitation of the active ingredient in two pesticides are achieved using LiChrospher 60 RP-select B (250 x 4 mm, 5 μm) column, UV detection at 220 nm, temperature at 250C, mobile phase consisted of acetonitrile and water (60/40; V/V) and flow rate of 1 mL/min. The ethod is validated by testing linearity, precision, recovery, LOD and LOQ. The values for multiple correlation coefficient (R2 > 0.999), relative standard deviation (RSD) of retention time and peak area (RSD ≤ 1.18 %), recoveries ranged from 98.16 % - 101.38 %, with RSD of 0.10 % - 1.96 %, revealed that the developed method has a good linearity, precision and accuracy. The proposed method is applicable for fast and accurate determination of active ingredient 2,4-D in the pesticides Monosan herbi and DMA-6

Determination of Dazomet in Basamid Granulat Using Reversed Phase HPLC

The reverse phase HPLC determination of dazomet (tetrahydro-3,5-dimethyl-1,3,5-thiadiazine-2-tione) in a pesticide formulation has been studied. HS Pecosphere 3 x 3 C8 (3 μm, 3.3 x 0.46 cm) and LiChrosorb C8 (5 μm, 25 x 0.4 cm) analytical columns were tested at a flow rate of 1.0 cm3 min-1, column temperature of 25 °C and UV detection at 280 nm. The best separation of dazomet from its dehydro-dimer forms was achieved with a mobile phase containing acetonitrile-water in the volume ratio 15 : 85 on a HS Pecosphere column, and acetonitrile-water in the volume ratio 30 : 70 on a LiChrosorb C8 column. The HS Pecosphere column showed a better peak symmetry, separation factor, and multiple correlation coefficient. The retention time and peak area for the HS Pecosphere column were precise within a day and between days as indicated by the ANO VA test, in contrast to the LiChrosorb column, which showed lost of efficiency

SPE-RRLC DETERMINATION OF SOME PESTICIDE RESIDUES IN APPLE JUICE

This paper presents the development of RRLC (Rapid Resolution Liquid Chromatography) method for simultaneous determination of pesticides methomyl, methidathion and propiconazole in different clear apple juice samples. The experiments are performed using rapid resolution liquid chromatography system coupled with UV-VIS diode array detector. The developed high speed reversed-phase (RP) liquid chromatography method is carried out on the Purospher® Star RP-18 endcapped (30 mm × 4 mm; 3 μm) column, mobile phase consists of acetonitrille and water (50/50, V/V), flow rate of 1 mL/min, column temperature at 25 ºC and UV detection at 220 nm and 235 nm. Prior to RRLC analysis, the samples are cleaned up and concentrated using a solid-phase extraction (SPE). To assess the validity of the developed method, the following parameters are examined: selectivity, linearity, repeatability (precision), limit of detection, limit of quantification and accuracy

COMMON NONCONFORMITIES DURING PROCEDURE FOR ACCREDITATION OF THE FOOD TESTING LABORATORIES IN THE R. MACEDONIA

During laboratory assessment in the frame of the accreditation procedure, they faced with number of nonconformities which are challenge for receiving the Certificate for accreditation and appropriate corrective measures shall be undertaken. Requirements that should be met by the food testing laboratories in the Republic of Macedonia, in order to gain accreditation certificate, contained in the standard МКС ENISO/IEC 17025:2006, ILAC (International Laboratory Accreditation Cooperation) document, ЕА (European Cooperation for Accreditation) document, Regulations and Procedures of the Institute for Accreditation of the Republic of Macedonia. In this paper the analysis is made and different proposals are given for the different ways of fulfilling of those requirements. The aim of this study is to emphasis the common nonconformities which are observed during realization of the Procedure of Accreditation of food testing laboratories and corrective measures undertaken. This investigation is of huge meaning for food testing laboratories which are already accredited and those which are planning to be accredited in the Republic of Macedonia. Furthermore, it is a very important for the Institute for accreditation of the Republic of Macedonia to come to conclusions for the weakest sides of the food testing laboratories and the assessment thereof. Such conclusions should initiate undertaking appropriate measures for improvement the Institute’s lead and technical assessors work towards nonconformities interpretation, identification and acceptance of the most suitable corrective measures

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR DETERMINATION OF PRESERVATIVES IN BEVERAGES

Benzoic and sorbic acids, and their sodium, potassium and calcium salts are widely used as preservatives in acidic foods and beverages. They inhibit the growth of molds and yeasts, and are also effective against wide range of bacteria which explains the benefit of their usage. The health effects have led to limitation on the concentrations that can be used in food and beverages. Because of that, the analytical determination of these preservatives is important for consumer interest and protection. Therefore, a new reversed-phased HPLC method for a fast, simple, accurate and precise determination of potassium sorbate and sodium benzoate in different beverages is developed. In this purpose, a HPLC system equipped with UV diode array detection is employed. Separation and determination of investigated preservatives are performed using Purospher® STAR RP-18 (30 mm x 4 mm; 3 μm) analytical column. Methanol/phosphate buffer (pH = 3.70) (20/80, V/V) is used as a mobile phase, with flow rate of 1 mL/min, constant column temperature of 25°C and UV detection at 225 nm and 255 nm. Successful separation conditions are obtained using an isocratic elution within 6 min. Accuracy, precision, limit of detection, limit of quantification, and linearity range are evaluated. The separation factor value of 1.128 showed that this method can be successfully used for simultaneousdetermination of benzoates and sorbates. The obtained data indicated that the concentration of investigated preservatives found in the analyzed beverages available on the local Macedonian markets is in accordance with Macedonian maximum levels for food safety

DEVELOPMENT OF HIGH SPEED RRLC METHOD FOR QUANTITATIVE DETERMINATION OF SOME PESTICIDE RESIDUES IN APPLE JUICE

Possibilities of normal-phase (NP) and reversed-phase (RP) liquid chromatography methods for determination of methomyl, methidathion and propiconazole residues in apple juice were studied. The investigations were carried out on various analytical columns using RRLC (Rapid Resolution Liquid Chromatography) system coupled with UV-Vis diode array detector. The best conditions for separation and quantitative determination of tested pesticides were obtained using reversed-phase mode and Purospher® Star RP-18 endcapped (30 mm × 4 mm; 3 μm) column. Fast and simple method for direct determination of methidathion and propiconazole in different apple juice matrix was developed. In accordance to European Commission regulation the tested parameters for method validation (selectivity, linearity, precision, limit of detection, limit of quantification and accuracy) were satisfied

DIFFERENT APPROACHES IN ANALYZING CHYMOSIN PURITY

Chymosin is a specific proteolytic enzyme found in rennet, and is the key enzyme in cheese production classified in the aspartic endopeptidases (EC 3.4.23.4). The aim of this study was to determine the purity of different commercially available chymosins and its equivalents using electrophoretic and chromatographic techniques. Chymosins produced by the company Chr. Hansen, CHY-MAX 200 and CHY-MAX Plus, CHY-MAX PowderExtra NB, as well as Maxiren 1800 Granulate from the company DSM, Sirnik from SZR – Travnik, Kraljevo and Planika from Mikroprocessing, Bileca were used as materials for this study. The purity level of the commercially available enzymes was analyzed using electrophoretic (sodium dodecyl sulfate polyacrylamide gel electrophoresis or SDS-PAGE) and chromatographic (Rapid Resolution Liquid Chromatography or RRLC) techniques. Results showed no presence of undeclared protein fractions due to inappropriate purification process in the samples except for CHY-MAX М 200 which had two protein fractions, most likely as a result of a polymorphism. All the CHY-MAX and Maxiren samples have chymosin as the active component (36 kDa), except for Planika and Sirnik which have a natural protease from R. miehei. Chromatographic analysis showed that beside the active component (chymosin), the preservative sodium benzoate was present in varying concentrations in all but CHY-MAX PowderExtra NB