摘要:

Increased incidence of sulphur (S) deficiency in crops has led to a greater need for S determination in plant tissues. Among the methods available for measurement of S, inductively coupled plasma atomic emission spectrometry (ICP‐AES) has been proved to be accurate and rapid. This paper compares digestion with HNO3‐HClO4, fuming HNO3‐KNO3and alkaline NaOBr prior to the S measurement by ICP‐AES. Both HNO3‐HClO4and fuming HNO3‐KNO3were found to give satisfactory results for five certified plant materials, with high accuracy and precision. The HNO3‐HClO4method involved a rigid temperature control, with slow ramp rates and a final temperature (190°C) lower than the boiling point of HClO4, to minimise the possibility of gaseous losses of S. Both methods can also be used for the simultaneous determination of phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn), and additionally potassium (K) with HNO3‐HClO4. In contrast, the alkaline NaOBr method was less suitable as a digestion procedure for S measurement by ICP‐AES, because it involved a large dilution factor and produced high blank values.

ISSN:0010-3624    

DOI:10.1080/00103629409369047

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This study determined the effects of soil preservation methods on inorganic nitrogen (N) analysis and evaluated methods of soil inorganic N analysis. Soils were preserved by oven‐drying at 55'C, air‐drying at 27°C, and freezing at ‐ 7°C. Inorganic N results were compared with initial N levels prior to imposing preservation treatments. Soil preservation effects on ammonium‐nitrogen (NH4+‐N) were not consistent across soil types. Soil nitrate‐nitrogen (NO3‐‐N) levels after air‐drying and freezing compared most favorably with initial levels indicating that both are acceptable methods of soil inorganic‐N preservation. Levels of NH4+‐N averaged across soils were 3.9 mg/kg for steam distillation, 4.2 mg/kg for sodium salicylate‐hypochlorite, and 3.7 mg/kg for indophenol blue. When compared with steam distillation averaged across soils, NO3‐‐N for cadmium‐copper (Cd‐Cu) reduction was 4 mg/kg greater, followed by nitrate electrode at 3 mg/kg, and salicylic acid at 2 mg/kg. Recovery of added N ranged from 83.3 to 94.8% for the NH4+‐N methods and from 74.8 to 112.4% for the NO3‐‐N methods with the nitrate electrode averaging 98.3%.

ISSN:0010-3624    

DOI:10.1080/00103629409369048

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An inexpensive piston‐action ball mill for the rapid preparation of plant and soil material for the automated analysis of15N and13C contents is described. A sample throughput of 150 samples per hour is possible with at least 50% of the particle sizes below 105 μm. The range of particle sizes obtained with the grinder allows a level of precision of less than 1% for the analysis of15N isotope enrichment using an automated continuous flow nitrogen and carbon isotope ratio mass spectrometer. Considerable savings in labor and costs are possible compared with other sample preparation systems currently available. The use of the mill is illustrated by a study of isotope enrichment of different plant organs of tropical forage species.

ISSN:0010-3624    

DOI:10.1080/00103629409369049

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A dual‐inlet isotope ratio mass spectrometer (VG‐SIRA 12, Isotech, Middlewich, England) using sealed‐glass combustion sample preparation and an automated single‐inlet isotope ratio mass spectrometry system (RoboPrep Sample Converter interfaced with a TracerMass Stable Isotope Detector, Europa Scientific, Crewe, England) were compared for δ13C analysis. Two hundred twenty four samples of plant and animal tissue were analyzed for S13C using the two systems. Delta13C values obtained from the two instruments were highly correlated (r2=0.986, P=0.0001). The slope of the relationship was not different from one nor was the Y‐intercept different from zero (Y=‐0.2 + 1.0X; P=0.86 and P=0.28 for the slope and Y‐intercept, respectively). In addition, samples from two complete experiments were run on both mass spectrometery systems and statistical analyses performed. In both experiments, differences between treatments were detectable using the RoboPrep system that were not detectable using the SIRA 12 system. In all cases mean δ13C values were comparable between the two systems, and coefficients of variation were low; well within acceptable experimental limits.

ISSN:0010-3624    

DOI:10.1080/00103629409369050

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629409369051

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629409369026

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor