Chemical Anaylses of Iron

Analytical Chemistry II

(a) Chemical Analyses – Iron

(b) ICP – Inductively Coupled Plasma

Material examined - Soil

Name of analyte – Iron

Sampling Procedures – A representative sample must be collected. The sample must remain dry and contaminant free. At least 50 mg are needed.

Sample preparation procedures - The soil sample is extracted with a mechanical vacuum extractor in a 0.2 M acid oxalate solution buffered at pH of 3.0 under darkness. The acid oxalate extract is then weighed and diluted with 0.1 N HCl.

(c) Series of Standards is used

Wavelength – 259.940 nm

ICP instrument design – Inductively Coupled Plasma Spectrometer ICAP 61E, Thermo Jarrell Ash Corporation, Franklin, MA

Slit setting – Normal slit width and length

How data is gathered – The ICP reads the QC after the high standard. If the QC falls within the range set by the operator the instrument proceeds to analyze the unknowns. If the QC is outside the range, the instrument restandardizes. The QC is analyzed approximately every 12 unknown samples. Then spectrometer then reads the output and displays the data as readable information.

Concentration of standards – 30ppm Iron and 5ppm Manganese

How standards are prepared – For high calibration standards mix 30mL of the iron primary standard with 5mL of the primary manganese standard. Add 30mL of 0.4 M acid oxalate solution and 16.0mL of 0.1 M DDBSA (Dodecylbenzene Sulfonic Acid) and then dilute to 1L with distilled water. The elements are added in that order to prevent element precipitation. The resulting solution contains 30ppm iron and 5ppm manganese. Store the solution in a polypropylene bottle.

Potential