Determination of three alkylphenol isomers in various water samples using a new HPLC method based on a duet stationary phase

The level of three alkylphenols (APs) 4-nonylphenol, 4-octylphenol and 4-tert-octylphenol was monitored in various water samples using a new developed and validated HPLC method. The HPLC method employed a column with a mixed-mode stationary phase (C18/SCX) using a mobile phase of water to methanol?=?15:85 (v/v) delivered at a flow rate of 1 mL/min at room temperature. Both diode array, DAD and fluorescence, FLD detectors were employed. The method is linear when APs concentration ranged from 0.025 to 0.5 μg/mL with a DAD detection at 279 nm and between 0.0008 and 0.1 μg/mL when the detection was made by FLD (excitation at 220 nm, emission at 315 nm). The limit of detection and limit of quantitation for alkylphenols were found to be 5 and 15 ng/mL, respectively (detection by DAD). The method was employed with good results for the determination of APs in the presence of polycyclic aromatic hydrocarbons in various water samples.     

Transfer rate of pesticide residues from medicinal plants in different types of extractive solutions

Abstract

Starting from the suspicion that the medicinal herbs may contain traces of pesticides and taking into account the risks of patients being exposed to contaminated products, the aim of this research was to evaluate the pesticide residues and the degree of their transfer (%) in three types of preparations (infusion, decoctionand cold maceration), for four medicinal plant species very often used in phytotherapy (Rosmarini folium, Menthae folium, Saturejae herba and Basilica herba). For each type of plant product, four samples were purchased from different manufacturers and they have been analyzed using gas chromatography- tandem mass spectrometry. One out of four samples of the same plant species contain at least one pesticide residue above the maximum level and shows a significant transfer of these residues in aqueous extractive solutions during extraction. The highest rate of pesticide transfer from medicinal plants was identified in infusions, recommended by many manufacturers.     

Summary of am APCA International Specialty Conference

Ozone continues to be one of the most important air pollution problems in the United States. While significant progress has been made, certain areas of the country still experience unhealthy levels of ozone and are unlikely to achieve current primary standards by 1988. With the prospect of an influx of millions of additional people, and their cars, into these areas by the year 2000, the problem of oxidant regulation and control becomes even greater. From this realization, the Effects Division of the Air Pollution Control Association conceived this conference topic. The summary that follows highlights key issues and findings from the conference held in November 1984 in Houston, Texas. The transactions of the conference will be available from APCA headquarters in the near future.     

Benchmarking a triplet of official estimates

The publication of official statistics at different levels of aggregation requires a benchmarking step. Difficulties arise when a benchmarking method needs to be applied to a triplet of related estimates, at multiple stages of aggregation. For ratios of totals, external benchmarking constraints for the triplet (numerator, denominator, ratio) are that the weighted sum of denominator/numerator/ratio estimates equals to a constant. The benchmarking weight, applied to the ratio estimates, is a function of the denominator estimates. For example, the United States Department of Agriculture’s National Agricultural Statistics Service’s county-level, end-of-season acreage, production and yield estimates need to aggregate to the corresponding agricultural statistics district-level estimates, which also need to aggregate to the corresponding prepublished state-level values. Moreover, the definition of yield, as the ratio of production to harvested acreage, needs to hold at the county level, the agricultural statistics district level and the state level. We discuss different methods of applying benchmarking constraints to a triplet (numerator, denominator, ratio), at multiple stages of aggregation, where the denominator and the ratio are modeled and the numerator is derived. County-level and agricultural statistics district-level, end-of-season acreage, production and yield estimates are constructed and compared using the different methods. Results are illustrated for 2014 corn and soybean in Indiana, Iowa and Illinois.