Certified antimony

Lead, arsenic, and antimony—determined in the solution obtained by boiling 10 g of the titanium dioxide for 15 min in 50 mL of 0.5 Nhydrochloric acid In addition to individual specifications, general specifications have been written for provisionally Hsted certifiable colors ... 

In contrast to specifying to suppliers what chemicals or materials are restricted, it is useful to specify exactly what chemicals and materials are desired. Once a material or chemical is well characterized, and it is considered benign with respect to human and environmental health, it can be added to a preferred or positive list (i.e., P-list). For example, a textile manufacturer may source certified organic cotton, or polyester made with antimony-free catalysts, to develop a product line based on these fibres. Or a cleaning product formulator may seek bio-based solvents or rapidly biodegradable surfactants consistent with their product development objectives. 

The product shall have the characteristic shining, needlelike structure, steel-grey color, and hardness of the naturally occurring crystalline mineral. The lump form of the antimony sulfide shall be clean and free from adherent gangue material or scale. Pulverized antimony sulfide shall be free from extraneous material as indicated by visual examination under a magnification that clearly shows the crystal structure. The manufacturer shall certify that the product has these physical characteristics... 

Two x-ray fluorescence spectrometers were used for the analyses a General Electric XRD-6 for iron, copper, tin, and antimony, and a General Electric XRD-5 for nickel, silver, and lead (the latter machine has updated electronics and gave superior results for these three elements). Four certified standards from the National Bureau of Standards were used for each element to obtain a straight line calibration curve using linear regression (10). The experimental conditions used for the determination of each element were given by Carter et al. (10). 

There are no certified standards for antimony species in aqueous solutions or natural waters currently available, making the direct evaluation of accuracy impossible at this time. We have tested for the possibility of systematic errors by checking the standards for the dif-... 

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