Dear Junzaburo Enaka, please check the following documents. My Regards

https://doi.org/10.1080/00103629009368279

https://doi.org/10.1080/00103629909370230

10.2134/agronj1991.00021962008300010034x

https://doi.org/10.1016/S0003-2670(00)88469-X

https://doi.org/10.1039/AN9648900061

https://link.springer.com/protocol/10.1007%2F978-1-4939-7136-7_15

https://link.springer.com/article/10.1007/BF00431199

https://link.springer.com/article/10.1007%2FBF01372647

https://doi.org/10.1021/ac60064a032

Dear Junzaburo Enaka as indicated by Abdelkader BOUAZIZ there is quite a large body of literature available in which this topic is addressed. Here is one more potentially useful reference entitled Determination of Total Sulfur in Soils and Plants by an Automated Dry Combustion Method. This article is available as full text on RG.

Article Determination of Total Sulfur in Soils and Plants by an Auto...

Please consult Frank T. Edelmann

Hi;

Sulmograph determination is a technique that consists of determining sulphur by burning the sample in a stream of oxygen at 1350°C.

S + O2 = SO2

The S02 from the combustion of sulphur is absorbed in an oxidizing solution:

H2S04 + H20 in which C02 is not retained.

S02 + H202 = H2S04

The sulphur concentration is determined by the change in conductivity before and after the S02 passes through the cell containing the oxidizing solution.

With my best regards

Dear Junzaburo Enaka ;

The colorimetric determination of total sulphur in plants is carried out as follows: The plant samples are first mineralized by a dry process with pre-treatment with Magnesium Nitrate. The sulphates formed after addition of BaCl2 are determined by turbidimetry of barium sulphate. It is necessary to carry out the mineralization under perfectly controlled temperature conditions to avoid loss of Sulphur by volatilization.

Reagents

- Magnesium Nitrate Mg(NO3)2 6 H2O) Ct 9%.

- HC1 R.P.

- 2% Hydroxylamine Hydrochloride (HCl, NH2OH)

-Tween 20 (add the Tween after adjusting almost all the distilled water so as to avoid the formation of abundant foam).

-Standard Sulphur solution at 1000 ppm S prepared by weighing 5.447g/1 of dried K2SO4 & oven drying at 80°C.

In porcelain capsules weigh exactly 300 mg of finely ground vegetable powder dried at 80°C. Add 5 ml of Magnesium Nitrate solution and III drops of RP. Cover with a tray and leave to stand for at least 4 hours or preferably overnight. The mixture then takes on a light brown color. Heat on a hot plate without exceeding 180 °C for 3 hours), then in the oven at 400-450 °C until the residue is perfectly white (2 to 3 hours).

Moisten the residue with a few ml of distilled water. Filter through a quick and wet filter, collecting in a 25 ml volumetric flask, wash the residue on the filter with lukewarm water, adjusted to volume with distilled water. Then take 0, 1, 2, 3, 4 and 5 ml of a standard solution of S in a 25 ml (x ml) volumetric flask. Add 2 ml of hydroxylamine hydrochloride and distilled water to a volume of 20 ml.

In a 150 ml beaker add 100 ml of BaCl2 solution, and add 1 ml of S standard solution. Using a stopwatch, add 2 ml of BaCl2 solution with continuous stirring on a magnetic stirrer, make up to the mark with distilled water and stir 2 to 3 times vigorously. Measure with a colorimeter after 6 min.

My regards

Thank you everyone, I am surprised to receive answers from so many people.

I haven't read all of them yet, but I would like to see a lot of answers.

Sir, you can follow the Sulmograph determination for S- estimation.