Sulfate determination

Benzidine hydrochloride solution (for sulfate determination) mix 6.7 g of benzidine [Ci2H8(NH2)2] or 8.0 g of the hydrochloride [Ci2H8(NH2)2 2HC1] into a paste with 20 mL of water add 20 mL of HCl (sp. gr. 1.12) and dilute the mixture to 1 liter with water each mL of this solution is equivalent to 0.00357 g H2SO4. 

Sulfate is the final metabolite of sulfur-eontaining proteins therefore, its eontent detenuination appears to be a very informative test in diagnosties of some diseases. However, duration and laboriousness of traditional proeedures of sulfate detenuination prevent use of this test in everyday laboratory praetiee of elinieal analysis. In this ease, method of direet potentiometry, widely used in the determination of biologieal fluids eleetrolytie eomposition, seems to be very promising. In this work, the possibility of sulfate determination in urine using speeially manufaetured sulfate-seleetive eleetrode is diseussed. 

Several sulfate determinations in model solutions and urine samples were earried out. The results are of suffieiently good reprodueibility (within 10% rel.) and are in agreement with gravimetry and nephelometry data. This faet allows us to reeommend this method for express-determination of sulfate in urine. 

Methods of sulfate determination used in common practice suffer from essential disadvantages (time consumption, laboriousness, low sensitivity, etc.). For this reason, creation of sulfate-selective electrode suitable for direct potentiometric determination of this ion, has been attempted for a long time. Nowadays, nearly a dozen of sulfate-selective electrodes based on charged or neutral carriers of different stmcture have been described. Flowever, no known receptors for sulfate ions are available commercially. 

Alcohol ether sulfates also biodegrade rapidly but not as rapidly as alcohol sulfates. Primary biodegradation of alcohol (2 EO) ether sulfates determined in the same conditions as primary alcohol sulfates in Table 30 is shown in Table 33 as reported by Borsari [414]. 

There are several potential sources of error in these methods. The filters routinely used have a relatively high and somewhat variable sulfate content, so that, at concentrations lower than 10 Mg/m and sampling periods less than 24 h, the reliability of tlie sulfate measurement is reduc. Several different types of filtering media adsorb sulfur dioxide during the ftrst few hours of sampling this alters the amount of sulfate observed. This interference can become critical when sampling periods are less than 24 h and the concentration ratio of sulfur dioxide to sulfate is greater than 5 1. Interference can also be introduced by hot-water extraction when reduced sulfur compounds like sulfite are present, because they are oxidized to sulfates in this process. Another possible error source is that some of the various analytic procedures us for sulfate determination may be influenced by other substances also present in the particulate matter. 

Vilela-Silva, A. C., Alves, A. P., Valente, A. P., Vacquier, V. D., and Mourao, P. A. (1999). Structure of the sulfated alpha-L-fucan from the egg jelly coat of the sea urchin Strongylocentrotus franciscanus Patterns of preferential 2-0- and 4-O-sulfation determine sperm cell recognition. Glycobiology 9, 927-933. 

Either the residue from the sulfate determination or a fresh 1-g sample is used for the determination of pyrite sulfur content. The sample is added to dilute... 

If a new sample is used for the determination of pyrite iron, the iron determined by these procedures represents the combination of the pyrite and nonpyrite iron. The amount of nonpyrite iron must then be determined separately and subtracted from the amount determined. If the residue from the sulfate determination was used, the iron determined by the foregoing procedures represents the pyrite iron. Once the correct value for the pyrite iron is determined, the pyrite sulfur is calculated using the following expression ... 

A. Bettero and P. Bollettin, Atropine sulfate determination by derivative spectroscopy HPLC, Ann. Chim., 75 351 (1985), Rome. 

Sulfate Determine as directed in Sodium Sulfate under Colors, Appendix me. 

Sulfate Determine as directed in Sulfate Test under Chloride and Sulfate Limit Tests, Appendix IIIB. Any turbidity produced by a 200-mg sample does not exceed that produced by a control containing 200 pig of sulfate (S04) ion. 

Lead Determine as directed under Lead Limit Test, Appendix MIR, using a solution of 1 g of sample, accurately weighed, in 10 mL of water and 4 p,g of lead (Pb) ion in the control. Sulfate Determine as directed in the Sulfate Limit Test under Chloride and Sulfate Limit Tests, Appendix IIIB. Any turbidity produced by a 1-g sample does not exceed that shown in a control containing 300 p,g of sulfate (S04). 

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