KOSEN 한인과학기술자네트워크

>안녕하세요. > >sulfate content 측정방법이 궁금합니다. >사실 관련논문을 보고 있지만, 잘 이해가 되질 않아서요. > >저는 polymer의 항산화능에 대해 공부하고 있는데요. >sulfate 함량이 큰 영향을 미치는듯 합니다. >제발 빠르고 정확한 답변 부탁드립니다. 아래는 sulfate 측정법과 관련된 기본적인 내용이고, 첨부한 문서를 보시면 sulfate를 측정하는 turbimetric 방법이 있습니다. 참고하시면 되겠습니다. Analytical Methods Chemical Analyses: Water: Sulfate Sulfate (SO42-) is a naturally occurring ion and may be present in waters over wide concentration range. Acidic drainage may contribute large amounts of sulfate from oxidation of pyrite and other sulfide minerals. Increased levels of sulfate are usually the first indication of acid generation. Sulfate concentrations can be measured by ion chromatography, colorimetry, gravimetrically, or turbidimetrically using either manual and/or automated procedures. The main limitation of sulfate occurs in the interpretation of data. The source of the sulfate ion can be incorrectly attributed to acidic drainage, when in fact it may be from solubilization of salts such as gypsum which, release sulfate but do not produce acid mine drainage. The standard method for sulfate analysis is the turbidimetric procedure whereby, sulfate ion in acidic medium is precipitated with barium chloride to form barium sulfate. The resulting suspension is measured by a photometer at 420 nanometers or with a turbidity meter. The instrument of use is calibrated with sulfate standards of known concentrations. Initial turbidity in the samples must be removed by filtration prior to analysis. The minimum detectable sulfate concentration by this method is 1 mg/L. The procedure is outlined in Standard Methods, Section 4500 E (Standard Methods, 1998). Sulfate concentrations can also be determined by ion chromatography. In this procedure, the sample anions of interest are separated on the basis of their relative affinities for a low capacity, strongly basic anion exchanger. The advantage of this method is that other anions can be determined at the same time (i.e. phosphate, nitrate) (Standard Methods, Section 4500 B) (Standard Methods, 1998). The gravimetric procedure is a classical method base on the low solubility of barium chloride (Standard Methods, Section 4500 C) (Standard Methods, 1998). The procedure is time consuming and is only used when sulfate levels are very high. Sulfate can be determined colorimetrically by the methylyhymol blue method (Standard Methods Section 4500 F) (Standard Methods, 1998). This colorimetric procedure can only be conducted on samples that are free of color and turbidity. For more information on measuring sulfate concentrations, see MEND, 2001.