Comparative studies of univariate and multivariate optimizations for manganese determination in antihypertensive drugs by electrothermal atomic absorption spectrometry

Comparative studies using the univariate and multivariate optimizations (factorial design) were undertaken to determine manganese in antihypertensive drugs by electrothermal atomic absorption spectrometry (ET AAS). For the univariate method, the optimum pyrolysis and atomization temperatures were 500 and 2200 °C, and for multivariate analysis, the temperatures were 500 and 2400 °C, respectively. No differences were observed between the methods with respect to the slopes of the calibration curves, recoveries, results for certified urine samples for the two levels, and the averages of the intra- and inter-assay coefficients of variation (CV) using Student t and F tests as a statistical tool (P < 0.05). Calibration was performed by matrix matching. All other studies were made using the optimized multivariate conditions. The characteristic mass was of 0.68 ± 0.17 pg (the recommended mass is 0.60 pg). The limits of detection and quantification were 0.23 and 0.77 µg L-1, respectively. Intra- and inter-assay studies on the drug spiked with 0.5, 1.0, and 1.5 µg L-1 of Mn yielded mean results of 3.6 ± 1.9% and 9.6 ± 2.2%, respectively. For the intra-assay evaluation, seven samples of each concentration were evaluated for Mn on the same day, whereas, for the inter-assay study, these solutions were analyzed in three replicates during three consecutive days. Recovery studies on the drug spiked with three levels of Mn (n = 7 for each level) furnished results between 101.4 ± 17.2% and 106.6 ± 7.5%. The results of a certified urine sample analysis (two levels of Mn) agreed at a 95% level of confidence. Forty eight antihy pertensive drug samples were analyzed, and the drug contents varied between 2.9 ng and 1.9 µg capsule-1.Key words: manganese, antihypertensive drugs, electrothermal atomic absorption spectrometry, multivariate optimization.

Mn(OAc)3-promoted hydroxylation of α-carbomethoxy-γ-lactones by molecular oxygen

The Mn(OAc)3-mediated hydroxylation of a series of α-carbomethoxy-γ-lactones by molecular oxygen is described. The reaction is regio- and stereoselective and gives α-carbomethoxy-α-hydroxy-γ-lactones. Key words: manganese acetate, γ-lactones, hydroxylation, molecular oxygen.

MANGANESE SOIL TESTS FOR BOTH DEFICIENT AND TOXIC LEVELS IN APPLE ORCHARDS

Soil pH and Mn extracted by 1.0 M NH4OAc (pH 7.0), 0.02 M CaCl2, 0.25 M MgCl2, 0.03 M H3PO4, DTPA and HF/HC1 (total Mn) from two soil depths (0–15 cm, 15–30 cm) were compared to leaf Mn concentrations of Delicious apple trees (Malus domestica Borkh) from 34 Okanagan Valley orchards. Leaf Mn concentrations ranged from deficient (below 25 μg g−1) to toxic (above 60 μg g−1). For all orchards (pH 3.5–8.4), leaf Mn concentration varied directly with soil Mn extracted from 15–30 cm depth by all extractants except HF/HCl (total Mn) and 0.03 M H3PO4, and inversely with pH at both depths. For soils with pH > 6.5, DTPA and 0.25 M MgCl2 extractable soil Mn (15–30 cm depth) was most closely related to leaf Mn concentration, whereas for soils with pH < 6.5, pH (15–30 cm depth) was the best indicator of Mn availability. Thus soil tests for Mn availability to apple trees may not perform equally well in toxic and deficient situations. Key words: Manganese, soil test, apple trees, Malus domestica Borkh

INFLUENCE OF DIETARY MANGANESE ON TISSUE TRACE MINERAL ACCUMULATION AND DEPLETION IN SHEEP

An experiment was conducted to investigate tissue trace mineral accumulation and depletion in sheep fed high dietary Mn in the form of reagent grade MnO. During the pre-trial phase, 32 wethers, 56 kg initially, were group-fed the basal corn-soybean meal diet (36 mg/kg Mn) for 8 days at which time eight sheep were slaughtered and tissues were taken to represent controls. For the remaining sheep, the experiment was divided into two phases of 6 wk and 12 wk; during the first phase (accumulation), the diet contained 8000 mg/kg supplemental Mn and during the second phase (depletion) the diet was the unsupplemented basal. Sheep were slaughtered at various intervals during both phases and tissue samples were taken. Manganese increased in all tissues measured during accumulation but decreased rapidly during the depletion phase. In general, liver and kidney Zn and Cu increased during the accumulation phase but tissue Fe decreased during this phase. MnO appeared to be a relatively safe supplemental source of Mn for sheep. Key words: Manganese, trace minerals, tissue minerals, sheep