Indian Journal of Chemical Technology Vol.lO, July 2003, pp. 373-381

Articles

Determination of total sulphur in inorganic compounds-An overview

Y S Sayi*, P S Shankaran, C S Yadav & G C Chhapru

Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India

Received 12 June 2001; revised received I May 2003; accepted 23 May 2003

Sulphur is invariably present in all materials either as an impurity or as a major constituent. Severa~ methodologies are available to determine the sulphur content both at trace level and percentage l~vels: So~e of the techruques employed for the determination of total sulphur in inorganic materials have been briefly descnbed m this paper.

Sulphur compounds play an important role in tech­nolooical and scientific fields. Sulphur can be used as

0 .

an oxidising or reducing agent depending on the envi-ronmental conditions. The largest use of sulphur (about 85% of global production) is in the form of sulphuric acid, which finds applications in almost all industries (fertilizers, chemicals, pigments, steel, rayon and film or petroleum products) . In elemental form it is used in paper, pulp and rubber industries. Sulphur can be present as a trace impurity or as a major constituent. It can be present as free or com­bined form (as sulphide, sulphate or sulphur analogs of carbonyls, carboxylic acids, etc.) . Sulphur present even at trace level in stainless steel has a deleterious influence on its mechanical properties (sulphur em­brittlement). Though both sulphur and carbon present as an impurity cause damage to the material, not much importance seems to have been given to the determi­nation of sulphur as compared to carbon. This is re­flected from the fact that the quantum of work pub­lished on estimation of carbon is much higher than that on sulphur; and the commercial equipments for the determination of carbon are many compared to that for sulphur. Sengupta1 has compared various methods available for the determination of carbon and sulphur in ferrous metals. Most of the recent work is on the determination of sulphur in steel samples. Apart from the determination of total sulphur content, it is essential to find out the sulphur functional group, since the functional group decides the properties of the product. The present overview is limited to the available methods for the determination of total sul­phur in solid inorganic materials. The functional

*For correspondence (E-mail: yssayi @magnum.barc.ernet.in)

group can be determined by employing infrar~d .spec­troscopy and mass spectrometry. However, this IS be­yond the scope of this paper.

Experimental Procedure

Sampling In the analytical work, sampling of the material is

the first and foremost important step. As has been stated by Murphl the only truly representative sam­ple consists of 100% of the material , which is imprac­tical and hence compromise is to be made in choosing the sample size, depending on the accuracy needed. Different techniques have to be followed in sampling depending on (i) on-line collection of samples during the production or (ii) samples to be chosen from bulk materials . In the first case, at regular intervals of pro­duction, samples are drawn for the analysis. In the case of gases and homogeneous liquids (<:ifter mixing thoroughly) any small portion of the sample is a true representative of the whole lot. In sampling of solids, depending on the nature of the material (tab­lets/pellets, powder or ingots) an appropriate method is to be chosen. Tablets/pellets are arranged serially and samples are chosen at random. In case of pow­ders, a number of small samples are collected from different parts randomly and mixed. Small portions are collected from this lot and the process is continued till required sample size is achieved. In the case of ingots, holes are drilled in the representative ingots and are mixed, powdered and required amount of sample is collected as mentioned above. Kratochvil and Taylor3 have given an excellent account on sam­pling of solid samples for chemical analysis . More details can be obtained from standard quantitative analysis books4

•

Articles

Analysis

Treatment of the sample After choosing the sample size, the next important

step in the analysis is to convert the sulphur to a suitable determinable form. It can be in solid, liquid or gaseous state. Most of the techniques employed for the determination of sulphur are based on the analysis of the sample in liquid form. Hence it is of importance to have knowledge on the various methodologies available to dissolve the sample. Depending on the matrix, suitable medium is chosen. Most of the steel samples go into solution with HN03 or HN03 + HCl oxidation5 which converts all forms of sulphur into soluble sulphate. Samples containing silicon are treated with HN03 or HCl or HC104 in presence of HF. Refractory materials and other inorganic samples containing sulphur, which cannot go into solution by simple acid treatments, are subjected to fusion 6 with mild (sodium/potassium carbonate, magnesium oxide or their mixture) or strong (sodium peroxide, sodium carbonate or potassium chlorate) flux prior to dissolution. Mild fluxes are employed for treating ores and minerals containing small amounts of sulphur. In the fusion, the oxidation of sulphur to sulphate takes place from the atmospheric oxygen. Insoluble barium, calcium, strontium and lead sulphates can be dissolved only after the treatment with fluxes . During the fusion, the insoluble sulphates are converted into soluble sulphate and insoluble metallic carbonates. Yan et al.7 have used Na2C03 + MgO fusion mixture to dissolve coal. Strong fluxes generally employed are (i) sodium carbonate mixed with KC103 or KN03 and (ii) sodium peroxide. In the fusion with strong fluxes , the fluxes themselves are capable of oxidizing sulphur without the aid of atmospheric oxygen. Strong fluxes are employed in the dissolution of samples containing higher amounts of sulphur. Sodium peroxide is a powerful oxidising flux which can decompose any type of sample. However, care should be taken that there is no organic material in the sample. Yamada et al. 8 have employed KC103 and HN03 mixture for the dissolution of metal sulphide. After fusion, the sample is dissolved in water or HCI. An aliquot of the above solution is taken for the determination of total sulphur. In neutron/proton activation analysis sample can be in solid form. In the analytical methods wherein S02 or HzS are monitored, the solid sample is directly oxidised or reduced at high temperatures in presence of oxygen or moist hydrogen. H2S can also be

374

Indian J. Chern. Techno!., July 2003

liberated by reducing the sulphate solution with hydriodic acid and hypophosphorous acid mixture9

.

Analytical techniques In the analysis, one should be concerned about the

cost, availability of equipment, ease and accuracy of the method. Various methodologies are available for the determination of total sulphur content. They in­clude gravimetry; titrimetry; turbidimetry; spectro­photometry; electro chemical techniques like am­perometry, potentiometry, conductometry, polarogra­phy, coulometry, voltammetry, sulphur sensors; iso­topic techniques, gas chromatography, X-ray emission (fluorescence), combustion cum TC/IR detection, mass spectrometry, ICP-AES and chemiluminescence. Each method has its own advantages and limitations. For the determination of sulphur present in trace lev­els, turbidimetry, spectrophotometry, mass spec­trometry and isotopic techniques can be employed. However to improve the precision, low concentration samples can be pre-concentrated, prior to the analysis. For high sulphur content sampies, virtually any method can be adopted by suitable dilution.

Gravimetry The time tested gravimetric analysis involves the

precipitation of sulphate ions as barium sulphate, by the addition of barium chloride. The precipitate is fil­tered through ·ashless quantitative filter paper, washed and ignited at 850°C and sulphur is weighed as bar­ium sulphate. Gravimetry is generally employed in samples containing sulphur in bulk.

Tit rime try In the direct titration method, sulphate ion is ti­

trated with barium perchlorate using thorin as indica­tor10'11 . The end point is sharp and the change in the colour is from yellow to pink. The method is applica­ble to solutions that do not contain large amounts of foreign ions. Otherwise they have to be purified be­fore titration. An aliquot of the solution is taken in 80% alcohol medium and pH is adjusted to 2-4 with dilute perchloric acid prior to titration. A precision of 10% has been reported at few mg of sulphur content.

The titration of sulphate employing barium chlo­ride with tetra hydroxyquinone as an indicator12 is not as sharp as the above method.

In iodimetric titrations, sulphur present in the sam­ple is oxidised to so2 by high temperature combus­tion. The liberated sulphur dioxide is fed to a mixture of standard potassium iodide, hydrochloric acid,

Sayi et al.: Determination of total sulphur in inorganic compounds- An overview Articles

starch solution and small amount of standard potas­sium iodate. This mixture produces free iodine and the colour of the solution will be blue. so2 will react with this h and K1 will be formed rendering the solu­tion colourless. This colourless solution is titrated with standard KI03. while at the same time continuing feeding of the so2. h liberated is instantaneously util­ised by so2 being fed rendering the solution colour­less. This process is continued until no more S02 is available for the neutralisation of the h liberated, which is indicated by the persistence of blue colour. From this the sulphur content is calculated 13

. 5 ppmw of sulphur could be determined by this technique.

Sulphate is precipitated as barium sulphate and is dissolved in known excess of EDT A solution in pres­ence of ammonia. Excess amount of EDT A is titrated with standard magnesium salt using erichrome black T14"15. The amount of EDTA consumed for the disso­lution is proportional to the sulphur content. Gudz­hev15 determined 0.04-0.4% of sulphur at 2.2% R.S .D. Fontan and Olsina16 have developed an indirect method using Cu(II)-3,5 C12 PADAB indicator for the determination of sulphur in iron and other oxides.

In another method 17, sulphur in the sample is re­

duced to H2S at 850 - 900° C in presence of hydrogen, HI and NaH2P02. The liberated H2S is absorbed in alkali solution and titrated against standard Hg(OAc) solution in presence of dithiozone indicator.

Turbidimetry and nephelometry These techniques are applicable for colourless so­

lutions and for very low concentrations of sulphate. A suspension is formed by employing glycol-ethanol­water mixtures. The absorption (turbidimetry) or scattering (nephelometry) of light is applied on the suspension18. 3 f.!g of sulphur at ±1% precision has been determined by this method. In another method, the turbidity formed by BaCh has been employed for the measurement19. These are proportional to sulphur concentrations. Yan et al.1 have analysed coal sam­ples with RSD 0.44% with a recovery of 99.2-100.9%. Siriwardena20 has determined sulphur up to 2ppmw in cyanide extracts of gold and plating solu­tions after converting all forms of sulphur to sulphate by H20 2 treatment.

Spectrophotometry Sulphur containing sample is dissolved in a suit­

able medium. Sulphur is then reduced to H2S em­ploying hydriodic and hypophosphorous acid mixture.

It is then converted into Lauth's violet employing p-phenylenediamine in presence of an oxidising agent such as ferric ion and the absorbance is measured spectrophotometrically at 595 nm9. In another method21 , H2S formed by the reduction of stainless steel was absorbed in alkali and absorbence at 232 nm is monitored. From the calibration plot of absorption versus concentrations, the sulphur content in the sam­ple is obtained. Acs and Barabas22 have oxidised sul­phur to sulphur dioxide and determined it by spectra­photometrically with pararosaniline and formaldehyde and could estimate 5ppmw of sulphur. Abdel and El Shahat23 have determined sulphur in various types of samples using ferricyanide-thymolpthaleine reagent and measuring absorbance at 592 nm. Lai et al. 24 have absorbed the liberated so2 during combustion in standard KMn04 solution and measured absorbance at 530 nm. They observed that Beer's law is obeyed up to ~ 0.04% sulphur.

Electro chemical methods

Amperometry Sulphate in the solution can be directly titrated us­

ing standard lead nitrate solution to an amperometric end point25 in alcohol medium. Alternatively, in an indirect method, sulphate is precipitated as lead sul­phate, which is dissolved, and the lead content is de­termined by titrating with standard dichromate solu­tion26. From the amount of titrant consumed, the sul­phur content can be calculated. Sheu et al.21 have de­termined sulphur in CulnS2 at 10 mg sample size with +0.16% error and RSD ± 0.17%, employing am­perometry.

Potentiometry Garcia-Calzada et al.28 have employed potenti­

ometric analysis using sulphide selective electrode, for low sulphur content samples. The sulphur in solid sample is reduced to H2S employing HI and H3P02 mixture. H2S gas formed is absorbed in sodium hy­droxide solution containing ascorbic acid or hydra­zine. It is then titrated using sulphide selective elec­trode. The method is used to solutions containing 1 o-3

M sulphur with a precision of ± 5%. Bebeshko and Oleshko29 have used a mixture of phosphoric acid, tin chloride and trivalent titanium to reduce sulphur in the sample to H2S and estimated it by sulphide selec­tive electrode.

Conductometry The electrical conductivity of the sulphate solution

375

Articles

is measured after successive additions of standard barium chloride/nitrate/acetate30 solution. The amount of titrant at the point of change in slope of electrical conductivity is proportional to the concentration of sulphur. In another method, S02 formed by the com­bustion of sulphur present in the sample is absorbed in H20 2 and the electrical conductivity of the resulting H2S04 has been measured which is proportional to the sulphur content31

. Employing this technique, a preci­sion of± 10% was achieved at 1500 ppmw level.

Polarography

Sulphur is reduced to H2S and the gas is absorbed in suitable electrolyte like sodium hydroxide or so­dium hydrogen phosphate. Sulphide ion polarises the dropping mercury electrode resulting in anodic wave. The height of the anodic wave (diffusion current) is proportional to the sulphur content. Ravenda32 could determine H2S over the range 5x 1 o-4

- 3x 10·3 M. Han et al. 33 have absorbed H2S liberated during the hydro­gen reduction of sulphur in cadmium acetate solution and determined sulphur using dropping mercury elec­trode. The ease with which various sulphides get re­duced at 800° C in presence of hydrogen has also been incorporated in their studies.

Coulometry

Sulphur is oxidised to S02 and is absorbed in acidi­fied bromide solution and the liberated bromine is titrated electrolytically34

. From this sulphur content can be obtained. Lemm et al. 35 determined S02 liber­ated by the combustion of the sample in oxygen and argon mixture by coulometry over the range 1-1 OOOppmw. Song36 has studied the analysis of sulphur in coal by applying iodimetry - coulometric titration and could achieve a standard deviation of ± 0 .03%. Jiang et a/.37 have converted so2 formed during the combustion of iron ore into H2S03 by the electrolytic action. This has been ti trated by coulometry and over a wide range. Persits et a/. 38 have roasted the sulphur containing sample in dry oxygen at 1250 - 1300° C and after absorption of so2 formed in aqueous elec­trolyte solution and carried out coulometric tiltration. Wills et a/.39 could determine sulphur from a sample size of 0.5-20 mg containing 0.5-100% sulphur. The methodology includes trapping of all the oxides of sulphur liberated during the combustion of sample in hydrogen peroxide, volatalising the trap contents and sweeping with nitrogen gas through hot copper main­tained at 890° C, to convert all sulphur oxides quan-

376

Indian J. Chern . Techno!. , July 2003

titatively into S02, followed by coulometric titration with iodine.

Voltammetry Yamada et a/.8 have developed anodic stripping

voltammetry (ASV). The method involves dissolving samples and precipitation of sulphate ions as lead sul­phate by the addition of excess of standard lead nitrate solution . Unreacted lead is determined by ASV em­ploying mercury coated platinum micro electrode. In a sample size of 10-15 mg, a standard deviation of± 0.004% has been reported .

Solid state sensors Recently Zhang et al.40

.41 have developed solid

state electrochemical sulphur sensors for the determi­nation of sulphur in molten metals . The sensors have fast response time with good precision. Various meth­ods involved in the preparation of these sensors have been discussed. Gozzi and Granati42 have employed solid-state electrochemical sensor for in situ monitor­ing of sulphur in carbon-saturated iron.

Isotopic techniques There are two different techniques employed for

sulphur determination in the samples viz: (i) activation analysis and (ii) tracer method .

Neutron activation analysis 35S is ~active and has half-life of 87 days, and may

be produced by neutron irradiation of 34S, which has abundance of 4.2%. Similarly 32S (95% abundance) with (n,p) reaction gives ~ active 32P which has 14 days half-life. In activation analysis either of these two ~ active isotopes is monitored. In the absolute method, the sample is irradiated, purified and ~ activ­ity is measured. Das and Bhattacharayya43 have de­termined sulphur (0.25-3%) by monitoring 1.72MeV ~ of 32P produced from 32S(n,p)32P reaction. In an­other method Klie and Sharma44 have monitored in­tensity of 2130 KeY y photo peak belonging to 34P produced by 34S (n,p) 34P reaction. From this the sul­phur content can be calculated. In standard compari­son method a standard with known sulphur content and sample are irradiated simultaneously and from the ratios of 35S or 32P formed, the sulphur content is cal­culated. Souliotis45 could determine 20 ppmw of sul­phur by standard comparison method with an error of less than 5%.

Proton activation analysis Proton activation analysis employing 10.3 Mev

Sayi et al.: Determination of total sulphur in inorganic compounds-An overview Articles

Table !-Various techniques for the determ ination of sulphur

Technique Methodology Nature of sample Quantity of S and precision Ref

Gravimetry Weighed as BaS04 Any For bulk S content

Titrimetry Titration of sulphate ion with barium Water samples 10 ±I ppm 10,11

perchlorate using thorin as indicator Higher content: <I % error

With barium chloride usi ng tetrahydroxy 12

quinone as indicator Iodometry 5ppm 13

EDTA tritration using Erichrome Black- Se-S mixtures 0.04 - 0.4% with 14,15

T as indicator < 2.2% RSD Erichrome Black-T and Methyl red indi - Cast iron and other 820 ppm with RSD ± I% 16

cator oxides

H2S liberated from sample titrated with Inorganic salts, org. 17

Hg(OAC)2 with dithiozone indicator compounds and drugs

Turbidi- Turbidity formed by BaC12 Organic substances to 100 ppm 18

metry and with± 1% RSD Nephelo- Plant materials 3-4% RSD 19

me try Coal samples 1-5 mg SOJ50ml with RSD 7 Cynide extraction 0.44% 20 of gold ore and 2 ppm plating materia ls

Spectro- Reduce S to H2S and develop colour with Ceramic materi als lO- 600 ppm with 12% & 3% 9 Photo- p-phenylenediamine RSD at lower and higher me try amounts

ReduceS to H2S and absorb in alkali and SS samples 2 1 measure at 232 nm Oxidise S to S02 and colour development Selenium 5-1200 ppm with± 2% RSD 22 using pararosani line and forrna l dehyde

Oxidise S to S02 and colour development In mixtures of S Error± 0.2% 23 using ferricynide and thymolpthaleine compounds Oxidise S to SOz, absorb in KMn04 and Steel samples 0.002 - 0.04 % s 24 measure at 530 nm

Electro- Amperometry: titrate sulphate ion with 0.01 -0.001 M 25 chemical Pb(N03)z CulnS 2 with 0.17 % RSD 27

Sulphate ion precipitated as lead sui- Organic compounds RSD ±0.5% 26 phate, dissolved and lead titrated with dichromate Potentiometry: H2S liberated from sam- CaS and K2S04 200 - 700 ppm with RSD ± 5% 28 pic titrated with Pb(CI04)z using sulphide 29 selecti ve electrode

Conductometry : sulphate ion titrated with 30 barium ion

S02 liberated by ox idation absorbed in Coal tar fractions 20- 4000 ppm with 0.7% RSD at 3 1 H202 and coductivity of resulted H2S04 1500 ppm measured

(Contd)

377

Articles Indian J. Chem. Techno!., July 2003

Table !-Various techniques for the determination of sulphur

Technique Methodology Nature of sample Quantity of S and precision Ref

Polarography : Reduce sulphur to H2S, 5x l0-4-3x l0-3 M 32 absorb in suitable electrolyte. Height of anodic wave proportional to sulphur sulphides of Mg, 33 content Ca, Ba and Rare

earths Cou lometry: Sulphur oxidised to S02, 34,37,38, absorbed in suitable medium and titrated 39 electrolyt ically Iron and unalloyed 0.8 - I 064 ppm 35

steels Coke Std.Dev. ± 0.03% 36

Voltammetry: Precipitate sulphate ion ZnS, Nd2S3, USz 10- 15 mg sample wi th RSD 8 with excess Pb(N03)z, and determine 0.04% unreacted Pb by ASV Solid state sensors Molten metals 13- 140 ppm 40,41,42

Isotopic tech- Neutron ac ti vation: Coal 0.25- 3% 43,44 niques

Paper and beer 20 ppm with error< 5% 45

Proton ac tivat ion: Coal 1500 ppm with RSD 2% 46 Deuterium acti vati on: NiS thin films 47

Tracer exchange Various samples 10' 18 g of s 48

Gas Chromato- Oxidi sed or reduced to S02 or H2S and Ferrous metals 0.011 - 0.329% Sulphur with ± 49 graphy GC separation and detection 0.009 Std.Dev.

XRF Environmental High reproducibility 50 solids Zinc ore 51 Lighter e lements 52

Com bus- Oxidised Sulphur to S02, purified and Metals, alloys, ores, ppm to % level with 2 - 10% 53-62 tion TCIIR de- detected by TC or IR detector steel, ceramic male- RSD tection rial s

Mass spectra Oxidised Sulphur to S02 and measure Ceramic materials, ppm to % level with 3 - I 0% 63 me try pressure and composition sulphides RSD

Vacuum fusion, mass spectrometry Copper 10 ppm with 15% RSD 64 Flash combustion followed by GCMS Solids, liquids and 65

gases TIMS Cu and Fe alloys 3-80 ppm with RSD 0.16% 66 TIMS, for isotopic compositi ons Pb and Ba sui- 67

ph ides IDMS Steel samples 60- 3300 ppm with I %RSD 68

NIST and SS sam- 30 ppm with 2.5% RSD 69 pies

ICP-AES Reduced to H2S, fed to ICP-AES Semi con 0.5 ppm 70 ductors Cast steel and low 0.5 ppm with precision 3% 71 alloy steel

Chemilumi- Reduced to H2S, fed lo hydrogen fl ame 72 nescence and chemiluminescence measured

378

Sayi et al. : Determination of total sulphur in inorganic compounds-An overview Articles

protons e4s (p,n) 34Cl] has also been developed46.

However minimum 1500 ppmw could be determined. The nuclear reaction 32S(d,p)33S gives 7 peaks well

visible on the energy spectra of the emitted protons over the range 1100 and 1450 keY. Based on this David et a/.47 have analysed nickel sulphide thin films for sulphur content.

Tracer technique

This method is based on the principle that the chemical behavior of all isotopes is same and in direct contact of sample with 35S tracer results in equilib­rium of 35S between the sample and the tracer through exchange reactions . The exchange between the tracer and the sample is allowed to take place by chemical reactions, separations, solubilities and or coprecipi­taion . From the isotopic composition of tracer before and after equilibration, the sulphur content in the sample is calculated. By using this technique 10-18 g of sulphur can be determined. Kohl et a/.48 have dis­cussed the amount of tracer required for various types of jobs.

Gas chromatography

Sulphur in the sample is oxidised to S02 or reduced to H2S and the gas is analysed by gas chromatogra­phy. From the pressure and composition data sulphur content is calculated. By employing silica gel column, 100 ppmw of sulphur in ferrous materials was deter­mined after combustion to S02

49.

X-ray emission (fluorescence)

In this technique, the sample is irradiated with high intensity X rays The changes in the energy appear as photons with characteristic wave lengths of the atom. The frequency of occurrence of these fluorescent X­rays is a measure of the concentration of the element present. Meduna and Schaefer50 have determined sul­phur in environmental samples while Gyves et a/.51

have determined sulphur in zinc ore. The analytical range of lighter elements was extended by excitation

. h L d. . 52 Wit tungsten a ra IatiOn .

Combustion cum TC/IR detection

Sample is subjected to combustion in flowing oxy­gen atmosphere at 1000°C, and the gases released are purified using various chemical traps. Purified S02 is detected by thermal conductivity detector53 or infrared detector54

. Chinese and Japanese55-62 have carried out

extensive work on the analysis of sulphur in steels, by

combustion followed by infrared detection. The tech­nique is quite fast and 5ppmw of sulphur can be esti­mated.

Mass spectrometry The sample is subjected to combustion in limited

supply of oxygen or oxygen generator at low pres­sures. Gases evolved are pumped into a known vol­ume. The pressure and gas composition are measured using differential oil manometer and a quadrupole mass spectrometer. From the data sulphur content is calculated63

. The method, though time consuming, is absolute one and can be applied for trace level to per­centage level of sulphur. The overall precision of 10% at trace levels and 3% at bulk ranges was achieved. Hickam64 measured 1-50 ppmw of sulphur by combi­nation of vacuum fusion-mass spectrometry. Baccanti and Colombo65 have determined sulphur by carrying out flash combustion at 1800° C and estimation of sulphur as S02 by gas chromatographic separation followed by mass spectrometric determination (GCMS). Employing this technique, isotopic ratios and sulphur content in solids, liquids and gases were determined. Paulsen and Kelly66 have determined sul­phur as AsS+ while Ramakumar et a/.67 have monj­tored metalS+ for the determination of isotopic ratios of sulphur by TIMS. Watanabe68 and Kelly et a/. 69

have determined sulphur in steel samples by isotopic dilution mass spectrome£ry (IDMS) using 34S as spike.

ICP-AES Okada et a/.70 have determined sulphur in samples

containing 0.5 ppmw S. The methodology involves oxidizing the s<>mple in presence of phosphoric acid and an oxidising agent followed by reduction of sul­phur to H2S in presence of reducing agent at 200 -400° C. This H2S is introduced in ICP and excited emission intensity is measured, which is proportional to the concentration of sulphur. Garcia et a/.7 1 have employed ICP-AES on H2S generated by reduction of the sample with a detection limit of 20 ppb sulphur and established ± 3% precision at 0.5 ppmw level.

Chemiluminescence Kuss 72 has reduced sulphur to H2S by HI, HCl and

NaH2P02 at 135° C. H2S is then swept by an auxiliary gas, argon or nitrogen into a hydrogen diffusion flame wherein H2S converts into sulphur molecules. The chemiluminescence of this reaction is measured at 350-410 nm.

379

Articles

Conclusions In the present overview, most of the available

methods for the determination of total sulphur have been desctibed. The methodologies , nature of the sample analysed and the amount of sulphur estimated with the precision quoted by various researchers is given in the form of a table . The fastest and most commonly used method is combustion cum infrared detection technique. It is known that there exists an equilibrium between S02 and S03 formed73 and the equilibrium shifts towards S02 with increase in tem­perature. Unless high temperatures are applied for combustion (> 1400° C), trace amounts of S03 may be formed, which could be left un-detected. Hence, it is necessary to generate calibration graphs using stan­dards with same matrix. However, availability of such standards is limi ted.

Acknowledgements The authors are thankful to Dr K L Ramakumar

and Dr V Venugopal, Head, Fuel Chemistry Division for their encouragement and di scussion.

References I Sengupta KG, Nat Met Lab Tech J, 36 ( 1994) 105. 2 Murphy W J, Anal Chem, 26 ( 1954) 441. 3 Kratochvi I B & Taylor J K, Anal Clwn , 53 ( 198 1) 924A. 4 Vogel A I, Text book of Quantitative Inorganic Analysis,

(ELBS), 1975. 5 ASTM Standards, American Society fo r Testing and Materi­

als, E 3 1 (1980). 6 ASTM Standards, American Society for Testing and Materi­

als, D 1757 (1980). 7 Yan B, Qiao Y, Wang J & Li P, Liluta Jianyan Hauxue

Fence, 35 ( 1999) 370; Chem Abstr, 13 1 (1999) 306453. 8 Yamada K, Sato N & Fujino T, Tohoku Daigaku Sozai Ko­

gaku Kenkyusho !ho , 54 (1998) 21; Chem Abstr, 131 (1999) 82255.

9 Rein J, Matl ack G, Waterbury G, Phelps R & Metz C, Los Alamos Scientific Loborat01y Report LA-4622, ( 1971 ).

10 Fritz J S & Yamamura S S, Anal Chem, 27 ( 1955) 146 1. II Scroggins L H, J Assoc Anal Chem, 59 (1976) 1135. 12 Schroeder W C, lnd Eng Clwn , 5 (1933) 403. 13 ASTM Standards, American Society for Testing and Materi­

als, E 30, 1980. 14 Belcher R, Bhasin R L, Shah R A & West T S, J Chem Soc

(London), 1958,4054. 15 Gudzhev V, Tsvetanov K & Panaiotova A, Metallurgiya

(Sofia), 31 (1976) 28: Chem Abstr. 86 (1977) 164758. 16 Fontan C A & Olsina R A, Talanta, 36 (1989) 945. 17 Adakhamov M M, Rasulova N, Yunnuskhodzhaeva R S!J &

Sagdullaeva T S, Khim Farm Zh, 19 ( 1985) 1 515; Chem Abstr, 104 (1986) 156093.

18 Tocnnies G & Bakay B, Anal Chem, 25 (1953) 160. 19 Novozamsky I & Eck R V, F Z Anal Chem, 286 (1977) 367. 20 Siriwardena A, F Z Anal Chem, 335 (1989) 395; Chem Abstr,

112 (1990) 150884.

380

Indian J. Chern. Techno!., July 2003

21 Ona A, Jpn Kokai Tokkyo Koho JP, 55051352, 15 April 1980. 22 Acs L & Barabas S, Anal Chem, 36 (1964) 1825. 23 Abdel B M M & El Shahat M F, Rev Roum Chim , 33 ( 1988)

875; Chem Abstr, 112 (1990) 47785. 24 Lai R, Lai Yu, Zhou H & Lin Y, Lihua Jianyan, Huaxue

Fence, 24 (1988) 373; Chem Abstr, 113 ( 1990) 34019. 25 Kalthoff I M & Pan Y D, JAm Chem Soc, 62 ( 1940) 3332. 26 Rulfs C L & Mackela A A, Anal Chem, 25 (1953) 660. 27 Sheu K C, Lee M L, Hwabg H L, Lin H Y & Yang M H, F Z

Anal Chem, 334 (1989) 143. 28 Garcia-Calzada M, Marban G & Fuertes A B, Anal Chim

Acta, 380 ( 1 999) 39. 29 Bebeshko G I & Oleshko 0 N, Otktytiya, /zo brei, Prom

Obraztsy, Tovarnye Znaki, 25 (1982'1 99; Chem Abstr, 97 (1982) i 92482.

30 Britton H T S, Physical Methods in Chemical Analysis, Vol II (Academic Press, New York), 1951 ,95.

31 Dong X, Huaxue Shijie, 27 (1986) 553; Chem Abstr, I 06 ( 1 987) l 05087.

32 Revenda J, Collect Czech Chem Commun, 6 (1934) 453. 33 Han Q, Xiang C, Zhou D & Sun Y, J Be1jing Univ Iron Steel

Techno[, 10 (1988) 487; ChemAbstr, 112 (1990) 111093. 34 ASTM Standards, American Society for Testing and Materi­

als, D 1355 ( 1967). 35 Lemm H, Leiber F, Voss E & Waldoefner K H, Stahl Eisen,

104 ( 1984) 1350; Chem Abstr, 102 ( 1985) 178279. 36 Song Z, Yejin Fenxi, 19 (1999) 54; Chern Abstr, 132 (2000)

202345. 37 Jiang Y, Wang T S & Wang X, Huagong Kuangwa Yu }ian­

gong, 29 (2000) 25; Chem Abstr, 134 (2001) 109865. 38 Persits V Yu, Babushkin P L & Shishkovskaya V V, USSR

SU 1,502,996, Otkrytiya /zobret, 31 ( 1989) 223; Chem Abstr, 11 2 (1990) 30017.

39 Will s K D, Huffman E W D & Huffman E W D Jr, Micro­chem J, 41 (1990) 139; Chem Abstr, 113 (1990) 34090.

40 Zhang Q, Dong X, Gao H, Qin H, Wu P, Song J, Cai A & Zhang :Z, Faming Zhuanli Shenqing Gongkai Shuomingshu CN 11 234 12 (1996); Chem Abstr, 130 (1999) 231577.

41 Zhang Z, Feng G, Zhang J & Cao C. Gangtie, 35 (2000) 57; Chem Abstr, 134 (200 1) 24891.

42 Gozzi D & Granati P, Metal/ Mater Trans B, 25 B (1994) 561: Chem Abstr, 121 ( 1994) 220373.

43 Das G C & Bhattacharyya P K, Nuclear and Radiochemisfly Symposium, NV CAR 95 ( 1995) 401.

44 Klie J H & Sharma H D, J Radioanal Chem, 71 (1982) 299. 45 Souliotis A G, Anal Chem, 36 (1964) 811. 46 Landsberger S, Giovagnoli A, Debrun J L & Albert P, lnt J

Environ Anal Chem, 16 (1984) 295. 47 David D, Caplan R & Beranger G, Stud Phus Theor Chem, 32

NM (1984) 279; Chem Abstr, 102 (1985) 71865. 48 Kohl J, Zentner R D & Lukens H R, Radioisotope Applica­

tions Engineering (Van Nostrand, Princeton , NJ), 1961 , 146. 49 Stuckey W K & Walker J M, Anal Chem 35 (1963) 2015. 50 Meduna U & Schaefer H P, Labor Praxis, 13 (1989) 130,

Chem Abstr, 111 ( 1989) 24 7097. 51 Gyves J, Baucells M, Gardellach E & 13rianso J L, Analyst,

114 (1989) 559. 52 Freitag K, Reaus U & Fleischhauer J, ::ipectrochim Acta Part

B, 44 B ( 1989) 499; Chem Abstr, 112 (1990) 47683. 53 Kunze W, Chem Labor Betr, 26 ( 1975) 432; Chem Abstr, 87

( 1977) 193080.

Sayi et al.: Determination of total sulphur in inorganic compounds-An overview Articles

54 Liu S, Yejin Fen.xi, 11 (1991) 45; Chern Abstr, 117 (1992) 82531.

55 Tomiyama S, Jpn Kokai Tokkyo Koho JP, 02, 73154 (1990); Chern Abstr, 113 (1990) 34137.

56 You Q & Wu T, Lihua Jianyan Huaxue Fence, 34 (1998) 76; Chern Abstr, 129 (1998) 210969.

57 Cao D, Lihua Jianyan Huaxue Fence, 35 (1999) 249; Chern Abstr, 131 (1999) 153110.

58 Takada K, Ashino T, Morimoto Y, Yasuhara H, Kurosaki M & Abiko K, Mater Trans, JIM, 41 (2000) 53; Chern Abstr, 132 (2000) 216207.

59 Kurakake Y, Sera K & Ichioka T, Jpn Kokai Tokkyo Koho JP 2000, 88780 (2000); Chern Abstr, 132 (2000) 259861.

60 Su T, Lihua Jianyan Huaxue Fence, 36 (2000) 431; Chern Abstr, 134 (2001) 50713.

61 Yang F, Han M, Yang Zx& Liu H D, Fenxi Shiyanshi, 20 (2001) 67; Chern Abstr, 134 (2001) 246631.

62 Ying H S, Yu Q & Sun X, Lihua Jianyan Huaxue Fence, 36 (2000) 431, Guangpu Shiyanshi 17 (2000) 631; Chern Abstr, 134 (2001) 125277.

63 Sayi Y S, Shankaran P S, Yadav C S, Chhapru G C, Rama-

kumar K L & Venugopal V, Proc Nat Acad Sci India, 72(A) Ill (2002) 241.

64 Hickam W M, Anal Chern, 24 (1952) 362. 65 Baccanti M & Colombo B, Tecnol Chim , 8 (1988) 128; Chern

Abstr, Ill (1989) 126197. 66 Paulsen P J & Kelly W R, Anal Chern, 56 (1984) 708. 67 Rarnakumar K L, Jayakumar S, Rao R M, Gnanayan L G &

Jain H C, 61h National Symposium on Mass Spectrometry,

Dehradun October 11-13, (1993) Paper no. ICT 7. 68 WatanabeK, Talanta, 31 (1984)311. 69 Kelly W R, Chen L T, Gramlich J W & Hehn K E, Analyst,

115 (1990) 1019. 70 Okada A, Yokote Y & Saito K, Jpn Kokai Tokkyo Koho JP 01

06748 (8906748) ( 1987); Chern Abstr, 111 ( 1989) 186586. 71 Garcia M A, Garcia 0 C, Sanchez U J E & Sanz M A, Quim

Anal (Barcelona), 9 (1990) 33; Chern Abstr, 113 (1990) 223708.

72 Kuss H M, Chern Labor Betr, 39 ( 1988) 494; Chern Abstr, 110 ( 1989) 17766.

73 Evans W H & Wagman D D, J Res Natl Bur Std, 49 (1952) 141.

381