Plant Digests Research Articles

Automated Turbidimetric Determination of Sulfate Sulfur in Soils and Fertilizers and Total Sulfur in Plant Tissues

Abstract An automated turbidimetric method has been developed for the rapid and accurate determination of sulfate. The method is practical and useful for accurately measuring total sulfur in plant tissues, and extractable sulfate in soils and fertilizers. The principle of intermittent reagent addition is used, which eliminates drift and sensitivity changes caused by coating of BaSO4 on tubing and cell walls. Also, the appropriate chemistry is used to minimize coating and interactions of the wash with the sample at a sampling rate of 30/h. The sensitivity of the method is excellent with a working range of 0–15 ppm sulfur for soils. For plant and fertilizer digests, the sample solutions are diluted to 0–35 ppm S. The precision as determined by repeated analysis of a soil sample extract was 0.58% relative standard deviation (RSD) with a mean of 9.26 μg extractable sulfate sulfur. On another soil sample, using a different extractant and extraction procedure, the RSD was 0.64%, mean of 9.29 μg/g. Multiple automated sulfur analyses on a plant tissue digest resulted in an RSD of 0.41% for a sample containing 0.21% S. The average recovery of sulfate sulfur on 5 Magruder Fertilizer Check Samples by the automated turbidimetric method was 100.6%, range of 99.8 to 101.4%, as compared to gravimetric analysis. The automated turbidimetric method for sulfate has excellent precision and sensitivity in plant tissue and soil analyses where gravimetric BaSO4 assays are not practical. The method is rapid, precise, and accurate for analysis of sulfate sulfur in fertilizers.

Isothermal distillation in flow injection analysis: Determination of total nitrogen in plant material

An isothermal distillation unit is incorporated in flow injection systems. The influence of surfactant, flow rates, alkalinity, ionic strength, collector stream pH, reagent concentration and sample volume in ammonia distillation are discussed. A method for the determination of total nitgrogen in plant digests employing Nessler reagent is proposed. This method, based on merging zones approach, is characterized by a sampling rate of 100 samples per hour, a precision better than 3%, a reagent consumption of only 100 μl per sample and virtually no base-line drift. The results agree with those obtained with the indophenol blue colorimetric method. The incorporation of isothermal distillation in flow systems with potentiometric measurement is also described.

Merging zones in flow injection analysis: Part 2. Determination of Calcium, Magnesium and Potassium in Plant Material by Continuous Flow Injection Atomic Absorption and Flame Emission Spectrometry

A flow-injection analysis system is described for the automatic determination of calcium, magnesium and potassium in plant material by atomic absorption and flame emission Spectrometry. Flow rates and damping factors were studied; the sample undergoes a dispersion of ca. 40-fold with automatic incorporation of lanthanum when necessary. The proposed method allows 300 determinations per hour with a typical relative standard deviation of 0.5% and a reagent consumption of only 500 μg of lanthanum per determination, which is about 1% the usual amount. The results for plant digests agree with those obtained by the standard a.a.s. procedure.

Semi-automatic determination of manganese in natural waters and plant digests by flow injection analysis

The first page of this article is displayed as the abstract.

Merging zones in flow injection analysis: Part 3. Spectrophotometric determination of aluminium in plant and soil materials with sequential addition of pulsed reagents

A flow injection procedure is described for the Spectrophotometric determination of aluminium in plant and soil material with eriochrome cyanine R. This system utilizes merging zones and sequential addition of pulsed reagents. A high degree of sample dispersion and pulsed neutralization reagent allow precise pH control; acid plant digests can therefore be analysed without pre-treatment. Iron(III) interference is avoided with ascorbic acid, and phosphate interference is negligible. The sampling rate is 120 samples per hour, reproducibility is better than 1% for a 5.0-ppm Al standard, and the calibration plot is linear in the range 0–20 ppm Al. Applied to soil and plant samples, the method gives recoveries of 98–101%.

Rapid determination of sulphate in natural waters and plant digests by continuous flow injection turbidimetry

The turbidimetric determination of sulphate as barium sulphate has been adapted to the continuous flow injection procedure of Růžicka and co-workers. The effects of reagent composition, reagent flow-rates and length of mixing coils have been investigated. Optimum conditions were established for the determination of sulphate in natural waters and in plant digests. The results agree satisfactorily with those obtained by a standard turbidimetric method and analyses can be carried out at a rate of up to 180 samples per hour.

Comparison of Atomic Absorption Flame Spectroscopy and the Official AOAC Method for Determining Copper in Plant Tissues

Comparison of Atomic Absorption Flame Spectroscopy and the Official AOAC Method for Determining Copper in Plant Tissues

Flow injection analysis : Part III. Comparison of continuous flow spectrophotometry and potentiometry for the rapid determination of the total nitrogen content in plant digests

The Berthelot reaction for the determination of ammonia by formation of indophenol blue, has been adapted to continuous flow spectrophotometry and the effects of acidity, temperature, ethanol content and sampling rate have been investigated; optimal conditions are described for the determination of nitrogen in Kjeldahl digests. Comparison of results obtained by this method, the air-gap electrode and classical distillation show no statistical difference at the 1% level, but the flow injection technique can be run at a much higher sampling rate (110–180 samples per h) than any other method and uses as little as 0.3 ml of digest per analysis.

Flow injection analysis : Part II. Ultrafast determination of phosphorus in plant material by continuous flow spectrophotometry

The effect of sample volume, tube length, tube diameter, peak height and sampling rate on the determination of phosphorus in acidic plant digests was investigated, and optimal conditions for the flow injection method are described. Sampling rates of 420 samples per hour were achieved without incurring problems from carryover of samples, and evidence was obtained that rates as high as 700 samples per hour are possible. The flow injection method was proved to be suitable for routine analyses and has obvious advantages over other automated or manual methods in sampling rate, simplicity of design and cost.

An automated procedure for the determination of aluminium in soil and plant digests

AbstractAn automated procedure for the determination of aluminium in soil and plant digests using the Technicon Autoanalyzer is described. Aluminium is determined with the complexing dye sodium alizarin‐3‐sulphonate (Alizarin Red S). The interfering effect of iron is removed with thioglycollic acid. The reagent gives a very reproducible and linear response up to 15 parts/million of aluminium. Leaf tissue samples tested included those from rubber, tea, maize, coconut, oil palm, sorghum and rice. Soil types tested were Serdang, Rengam, Munchong and peat.

ATOMIC ABSORPTION MEASUREMENTS OF Al IN PLANT DIGESTS AND NEUTRAL SALT EXTRACTS OF SOILS

Atomic absorption spectrophotometric measurements of Al in plant digests and neutral salt extracts of soils were studied. Using a new lamp (Westinghouse design) and 5 × scale expansion, 1.0 ± 0.08 ppm Al was measured. Lanthanum (2000 ppm) suppressed enhancements from Na, K, Sr, Fe and a mixture of a large number of constituents. The measurements in plant digests were independent of dilution, gave complete recovery of added Al and showed excellent agreement with the 8-quinolinolate colorimetric values. Similarly, there was complete recovery from soil extracts, but the measurements by atomic absorption were larger than by 8-quinolinolate or Aluminon. It was concluded that the new lamp provides adequate sensitivity, stability and freedom from interferences so that atomic absorption can be used for routine measurements of Al in plant digests and neutral salt extracts of soils.

Direct determination of lead in plant materials by atomic absorption spectrophotometry

AbstractBackground absorption is shown to result in spuriously high lead values in the analysis of plant digest solutions by atomic absorption Spectrophotometry. By measuring the absorbance of a spectral continuum in the region of the absorption line a correction can be applied. The corrected values are shown to be in reasonable agreement with values obtained cobrimetrieally for a wide range of vegetable foods.

The determination of phosphorus in Kjeldahl digests of plant material by automatic analysis

Abstract A method is proposed for the determination of phosphorus in plant material using a modified Kjeldahl digestion and a Technicon Autoanalyzer. The procedure depends upon the formation of phosphomolybdate and its reduction to molybdenum blue by ferrous ammonium sulphate. The method enables the simultaneous determination of phosphorus and nitrogen on the same plant digest.

A rapid polarographic method for the determination of zinc in siol extracts and plant-ash solutions

A rapid procedure developed for the preliminary purification of soil extracts and plant digests preceding the polarographic determination of zinc is described. The procedure meets the necessary requirements of precision and when used in conjunction with the polarographic procedure described by Barrows and Drossdoff (1960), proved desirable for routine analysis involving large numbers of soil or plant samples.

Leaf analysis as a guide to the nutrition of fruit crops. IV.—scheme for the rapid determination of copper, iron, manganese and zinc in plant material

AbstractA method is described for the rapid determination of copper, iron, manganese and zinc on separate aliquots of a single plant digest solution. The coefficients of variation for these elements should not exceed 5% for strawberry, blackcurrant, apple and plum leaves. More variable results may be obtained for zinc in raspberry leaves but the reason for this is not clear.