Development and validation of a fast high-performance liquid chromatography method for the determination of microencapsulated pyrethroid pesticides

Biomembranes from slaughterhouse blood erythrocytes as prolonged release systems for dexamethasone sodium phosphate

The present study investigated preparation of bovine and porcine erythrocyte membranes from slaughterhouse blood as bio-derived materials for delivery of dexamethasone-sodium phosphate (DexP). The obtained biomembranes, i.e., ghosts were characterized in vitro in terms of morphological properties, loading parameters, and release behavior. For the last two, an UHPLC/-HESI-MS/MS based analytical procedure for absolute drug identification and quantification was developed. The results revealed that loading of DexP into both type of ghosts was directly proportional to the increase of drug concentration in the incubation medium, while incubation at 37°C had statistically significant effect on loaded amount of DexP (P < 0.05). The encapsulation efficiency was about fivefold higher in porcine compared to bovine ghosts. Insight into ghosts' surface morphology by field emission-scanning electron microscopy and atomic force microscopy confirmed that besides inevitable effects of osmosis, DexP inclusion itself had no observable additional effect on the morphology of the ghosts carriers. DexP release profiles were dependent on erythrocyte ghost type and amount of residual hemoglobin. However, sustained DexP release was achieved and shown over 3 days from porcine ghosts and 5 days from bovine erythrocyte ghosts. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1046-1055, 2016.

Development and validation of a 'universal' HPLC method for pyrethroid quantification in long-lasting insecticidal mosquito nets for malaria control and prevention

OBJECTIVES

To outline the development and validation of a universal method for quantifying deltamethrin, permethrin and alpha-cypermethrin levels in a variety of long-lasting insecticidal mosquito nets.

METHODS

Using the HPLC conditions found in the CIPAC method for deltamethrin quantification, the method is based on a simple extraction technique for sample preparation (heating in isooctane at approximately 100 °C for 15 min). The method was validated for linearity, specificity, accuracy, precision, insecticide stability to extraction conditions and required extraction time for insecticide removal.

RESULTS

The method was found valid for insecticide quantifications for various types of nets, namely for deltamethrin coated on polyester nets, deltamethrin incorporated into polyethylene nets, permethrin incorporated into polyethylene nets, alpha-cypermethrin coated on polyester nets and alpha-cypermethrin incorporated into polyethylene nets.

CONCLUSIONS

This method will provide a more simplified approach to testing a variety of nets (different types of fibre) containing deltamethrin, permethrin or alpha-cypermethrin.

Effect of fipronil on brain and muscle ultrastructure of Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

The ultrastructure of Nilaparvata lugens brain cells was damaged by treatment at different fipronil concentrations. The cell showed swollen mitochondria and vacuolization, but no mitochondrial cristae. Rough endoplasmic reticulum (RER) fragmentation and degranulation were seen. The dilatation of endoplasmic reticulum cisterns was very prominent, and the predominant lamellar RERs were arranged chaotically. The Golgi apparatus demonstrated obvious changes in configuration, as dilated with closed cisternae and atypical vesicles. The mitochondria mainly showed large vacuolization in muscles. Nuclear degeneration and condensation and increased numbers of large hydropic vacuoles and lysosomes were observed. It was concluded that the effect on cellular components was fipronil-specific. Changes in cellular ultrastructure seem to be an appropriate ecotoxicological indicator of the insecticide's efficacy.

HPLC method validation studies on a specific assay for monomethoxypoly(ethylene glycol) succinimido carbonate (mPEG-SC)

An UV-HPLC method for the determination of the potency of mPEG-SC, 5 kDa (1) has been developed and validated. Validation acceptance criteria that is typical of small molecule method validation was successfully applied for this method. The method relies on the HPLC separation of mPEG-OH, 5 kDa (2) and a derivatized form of mPEG-SC, 5 kDa (1). 1-Naphthylmethylamine reacts with mPEG-SC, 5 kDa (1) to form a stable, strongly UV absorbing carbamate 3. When the eluent is analyzed by UV detection at 220 nm, the method was shown to be linear, precise and accurate. The limit of detection of the method was 0.1 microg.

Development of sensitive immunoassays for the detection of the glucuronide conjugate of 3-phenoxybenzyl alcohol, a putative human urinary biomarker for pyrethroid exposure

Pyrethroids are widely used in agriculture as insecticides. This study describes a sensitive enzyme-linked immunosorbent assay for the detection of the glucuronide conjugate of 3-phenoxybenzyl alcohol, a putative pyrethroid metabolite that may be used as a biomarker of exposure to pyrethroids. Four antisera were elicited against two different immunizing haptens. Antisera were characterized in combination with several coating haptens. The lowest IC50 value (0.5 ng/mL) was obtained with antiserum 1891 and 3-phenoxybenzoic acid-BSA conjugate as the coating antigen. Antiserum 1891 was highly selective for the target compound with an overall cross-reactivity of <0.3% to structurally related compounds. The assay sensitivity was negligibly affected by pH 4-9. A 5-fold improvement in IC50 was observed using a 10-fold concentrated phosphate-fuffered saline as the assay buffer. Compared to assays conducted in normal phosphate-fuffered saline, the maximal absorbance was almost identical. A good correlation (r 2 = 0.99 and 0.97 for urine samples A and B, respectively) was observed between spiked levels and the levels detected by the immunoassay.

Pesticides analysis by liquid chromatography and capillary electrophoresis

Nowadays, a wide range of pesticides are used in agricultural production, and their monitoring in samples of environmental and alimentary interest is of extreme importance to ensure, among others, the safety of consumption of foods. The aim of this work is to provide updated information about the major developments in CE and HPLC in pesticide analysis, covering relevant publications between 2004 and early 2006. The use of different sample pretreatment steps to provide a suitable extraction of these compounds from the different matrices as well as to increase the sensitivity of the determination is also discussed.