Validation of a Method for the Determination of Total Chromium in Rat Feces by Inductively Coupled Plasma Optical Emission Spectrometry

Abstract

The validation of a method for the determination of total chromium in Fischer-344 rat feces by inductively coupled plasma optical emission spectrometry following a rapid, atmospheric-pressure microwave digestion is described. The performance of the method was evaluated over the concentration range of 5.00 to 200 µg Cr/g feces. Data for method linearity, accuracy, precision, digest stability, and storage stability are presented along with limit of detection and limit of quantitation data. Data from a cross-validation method for B6C3F1 mouse feces are also presented. Following validation, the method was applied to analyze samples collected in support of two chronic toxicological investigations.

Keywords:

• Chromium
• feces
• inductively coupled plasma optical emission spectrometry

The analytical work was funded in full by the National Institute of Environmental Health Sciences, National Institute of Health, Contract Numbers N01-ES-05455 and N01-ES-65554.

Notes

^a Nominal Cr concentration in final analysis solution.

^b Calculated as (concentration of Cr (µg/mL) × 25-mL digest volume)/nominal 0.250-g wet tissue mass.

^a Internal standard corrected emission intensity for matrix and solvent standards.

^b Calculated with matrix regression equation: y = 0.09368(x) + 0.003240; r = 0.9992.

^c Calculated as (mean found [Cr] (µg/mL)/nominal [Cr] (µg/mL)) × 100.

^d Calculated as (mean blank corrected matrix response/blank corrected solvent response) × 100. Mean matrix blank response = 0.002600; solvent blank response= −0.0006811.

^e Calculated as (concentration of Cr (µg/mL) × 25-mL digest volume)/nominal 0.250-g wet tissue mass.

^a Calculated as (mean found [Cr] (µg/g)/nominal [Cr] (µg/g)) × 100.

^a Calculated as (mean found [Cr] (µg/mL)/mean reference [Cr] (µg/mL)) × 100.

^a Mean recovery for three preparations calculated against mean reference concentration.

^b Not applicable; two of three replicates lost during sample preparation.

^a Internal standard corrected emission intensity for matrix and solvent standards.

^b Calculated with matrix regression equation y = 0.09368(x) + 0.003240; r = 0.9992.

^c Calculated as (mean found [Cr] (µg/mL)/nominal [Cr] (µg/mL)) × 100.

^d Calculated as (mean blank corrected matrix response/blank corrected solvent response) × 100. Mean matrix blank response = 0.01093; solvent blank response = 0.001610.

^e Calculated as [concentration of Cr (µg/mL) × 25-mL digest volume]/nominal 0.250-g wet tissue mass.