Modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction combined with spectrofluorimetry for trace determination of ofloxacin in pharmaceutical and biological samples

Ofloxacin is a quinolone synthetic antibiotic, which acts against resistant mutants of bacteria by inhibiting DNA gyrase. This antibacterial agent is widely used in the treatment of respiratory tract, urinary tract and tissue-based infections, which are caused by Gram-positive and Gram-negative bacteria. In this work, an efficient modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction [M-IL-CIA-DLLME] was combined with spectrofluorimetry for trace determination of ofloxacin in real samples. In this microextraction method, hydrophobic l-hexyl-3-methylimidazolium hexafluorophosphate [[Hmim] [PF[6]]] ionic liquid [IL] as a microextraction solvent was dispersed into a heated sample solution containing sodium hexafluorophosphate [NaPF[6]] [as a commonion]] and the analyte of interest. Afterwards, the resultant solution was cooled in an ice-water bath and a cloudy condition was formed due to a considerable decrease of IL solubility. After centrifuging, the enriched phase was introduced to the spectrofluorimeter for the determination of ofloxacin. In this technique, the performance of the microextraction method was not influenced by variations in the ionic strength of the sample solution [up to 30% w/v]. Furthermore, [Hmim][PF[6]] IL was chosen as a green microextraction phase and an alternative to traditional toxic organic solvents. Different parameters affecting the analytical performance were studied and optimized. At optimum conditions, a relatively broad linear dynamic range of 0.15-125 microg I[-1] and a limit of detection [LOD] of 0.029 microg I[-1] were obtained. The relative standard deviation [R.S.D.] obtained for the determination of five replicates of the 10 ml solution containing 50 ug I"1 ofloxacin was 2.7%. Finally, the combined methodology was successfully applied to ofloxacin determination in actual pharmaceutical formulations and biological samples

Molecularly imprinted solid phase extraction for trace analysis of diazinon in drinking water

Amongst organophosphate pesticides, the one most widely used and common environmental contaminant is diazinon; thus methods for its trace analysis in environmental samples must be developed. Use of diazinon imprinted polymers such as sorbents in solid phase extraction, is a prominent and novel application area of molecular imprinted polymers. For diazinon extraction, high performance liquid chromatography analysis was demonstrated in this study. During optimization of the molecular imprinted solid phase extraction procedure for efficient solid phase extraction of diazinon, Plackett-Burman design was conducted. Eight experimental factors with critical influence on molecular imprinted solid phase extraction performance were selected, and 12 different experimental runs based on Plackett-Burman design were carried out. The applicability of diazinon imprinted polymers as the sorbent in solid phase extraction, presented obtained good recoveries of diazinon from LC-grade water. An increase in pH caused an increase in the recovery on molecular imprinted solid phase extraction. From these results, the optimal molecular imprinted solid phase extraction procedure was as follows: solid phase extraction packing with 100 mg diazinon imprinted polymers; conditioning with 5 mL of methanol and 6 mL of LC-grade water; sample loading containing diazinon [pH=10]; washing with 1 mL of LC-grade water, 1 mL LC- grade water containing 30% acetonitrile and 0.5 mL of acetonitrile, respectively; eluting with 1 mL of methanol containing 2% acetic acid. The percentage recoveries obtained by the optimized molecular imprinted solid phase extraction were more than 90% with drinking water spiked at different trace levels of diazinon. Generally speaking, the molecular imprinted solid phase extraction procedure and subsequent high performance liquid chromatography analysis can be a relatively fast and proper approach for qualitative and quantitative analysis of diazinon in drinking water

Molecular imprinted solid phase extraction for determination of atrazine in environmental samples

Solid phase extraction is one of the major applications of molecularly imprinted polymers fields for clean-up of environmental and biological samples namely molecularly imprinted solid-phase extraction. In this study, solid phase extraction using the imprinted polymer has been optimized with the experimental design approach for a triazine herbicide, named atrazine with regard to the critical factors which influence the molecular imprinted solid phase extraction efficiency such as sample pH, concentration, flow-rate, volume, elution solvent, washing solvent and sorbent mass. Optimization methods that involve changing one factor at a time can be laborious. A novel approach for the optimization of imprinted solid-phase extraction using chemometrics is described. The factors were evaluated statistically and also validated with spiked water samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. Also, in order to the evaluate efficiency of the optimized molecularly imprinted solid-phase extraction protocols, enrichment capacity, reusability and cross-reactivity of cartridges have been also evaluated. Finally, selective molecularly imprinted solid-phase extraction of atrazine was successfully demonstrated with a recovery above 90% for spiked drinking water samples. It was concluded that the chemometrics is frequently employed for analytical method optimization and based on the obtained results, it is believed that the central composite design could prove beneficial for aiding the molecularly imprinted polymer and molecularly imprinted solid-phase extraction development

Optimization of sample preparation procedure for evaluation of occupational and environmental exposure to nickel

Nickel is an important constituent widely used in different industrial processes for production of various synthetic materials. For evaluation of workers' exposure to trace toxic metal of Ni [II], environmental and biological monitoring are essential processes, in which, preparation of samples is one of the most time-consuming and error-prone aspects prior to analysis. To evaluate factors influencing quantitative analysis scheme of nickel, solid phase extraction using mini columns filled with XAD-2 resin was optimized with regard to sample pH, ligand concentration, loading flow rate, elution solvent, sample volume [up to 500 ml], elution volume, amount of resins, and sample matrix interferences. Nickel ion was retained on solid sorbent and was eluted with followed by simple determination of analytes by using flame atomic absorption spectrometery. Obtained recoveries of metal ion were more than 92%. The amount of the analyte detected after simultaneous pre-concentration was basically in agreement with the added amounts. The optimized procedure was also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. The developed method promised to be applicable for evaluation of other metal ions present in different environmental and occupational samples as suitable results were obtained for relative standard deviation [less than 10%]. This optimized method can be considered to be successful in simplifying sample preparation for trace residue analysis of Ni in different matrices for evaluation of both occupational and environmental exposures

[Design, construction and performance of chromium mist generator]

The chromium mist generator is an essential tool for research and for making evidence-based recommendations in evaluating air pollution and its control systems. The purpose of this study was to design and construct a homogeneous chromium mist generator and to look at the effects of factors such as sampling height and distance between samplers in side-by-side sampling on the chromium mist sampling method. First we developed a mist generator, using a chromium electroplating bath in pilot scale. Concentrations of CrO3 and sulfuric acid in plating solution were 125 g L-1 and 1.25 g L-1, respectively. To set up permanent air sampling locations, a Plexiglas cylindrical chamber [75 cm height, 55 cm i.d] was installed as the bath overhead. Sixty holes were made on the chamber in 3 rows [20 in each row]. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and the related factors were studied using a side-by-side air sampling method. Forty-eight clusters of samples were collected on polyvinyl chloride [PVC] filters contained in sampling closed-face cassettes. Cassettes were located 35, 50, and 65 cm above the solution surface with < 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed by the NIOSH method 7600. ANOVA tests showed no significant differences between locations in side-by-side sampling [P=0.82] or between different sampling heights or sampler distances [P=0.86 and 0.86, respectively]. However, there were notable differences between means of coefficients of variation [CV] in various heights and distances. We conclude that the most chromium mist homogeneity could be obtained at a height of 50 cm from the bath solution surface and with a distance of < 7.5 cm between samplers