Determination of multiclass pesticide residues in apple juice by gas chromatography-mass selective detection after extraction by matrix solid-phase dispersion.

A multiresidue method is described for the analysis of 106 multiclass pesticides (organochlorine, organophosphate, carbamate, pyrethroid, and triazine classes) in apple juice in a single injection. The determination procedure was based on matrix solid-phase dispersion of juice on diatomaceous earth in a glass column and subsequent extraction with a mixture of hexane-dichloromethane (1 + 1) at a flow rate of 5 mL/min. The analytes were determined by capillary gas chromatography with mass spectrometric detection and confirmed by their retention times and ion ratios. The coefficients of variation for analysis of samples fortified over the range of 0.01-0.2 mg/kg were 1.62 to 18.4%, and the recoveries for all analytes were between 70 and 110%.

Effects of foliar iron application on iron concentration in polished rice grain and its bioavailability.

Iron (Fe) deficiency in humans caused by inadequate dietary intake is a global nutritional problem. A glass house pot experiment was conducted to evaluate the effect of foliar FeSO4 containing applications on concentrations of Fe, Zn, and Fe bioavailability in polished rice among five rice cultivars. The results showed that foliar application of FeSO4, FeSO4, plus nicotianamine (NA), and FeSO4 plus NA with ZnSO4 increased the grain Fe concentration by 16.97%, 29.9%, and 27.08%, respectively. The grain Fe bioavailability also increased by foliar application of FeSO4, FeSO4 plus NA, and FeSO4 plus NA with ZnSO4; these represent increases of 12.63%, 20.86%, and 18.75%, respectively. Foliar FeSO4 containing applications improved the Fe bioavailability and might be attributed to the reduction of phytic acid and the increase of Fe concentration in polished rice. Addition of ZnSO4 to foliar Fe application increased both Fe and Zn content without altering Fe content and bioavailability. In addition, the cultivar difference in Fe and Zn concentration was observed and may be due to the genetic control of leaf absorption and seed deposition of foliar application. Furthermore, the cultivar difference in Fe bioavailability observed might be attributed to the variation of grain Fe, phytic acid, and total phenolics contents among the five rice cultivars. The results suggested that foliar FeSO4 containing applications represent a promising agricultural approach to reduce Fe deficiency in countries where polished rice is extensively consumed.