D4629_11 (17) 02-2018

Obtain a test specimen using the procedure in section 8 of the written standard. The nitrogen concentration in the test specimen must be less than the concentration of the highest standard used in the calibration. Injection volumes ranging from 3 microliters to 100 microliters are acceptable, depending on the instrument being used. The size of the injected sample shall be similar to the size of the injected standards used for calibration. Flush a clean microliter syringe several times with a sample to be determined, and introduce it into the furnace using the procedure outlined in 10.2 through 10.4 of the written standard, depending on whether a boat inlet system is being used. For samples with total nitrogen concentration in the range 1 milligrams per kilogram to 100 milligrams per kilogram, sample sizes injected are typically up to 10 microliters. For samples with total nitrogen concentration less than 1 milligram per kilogram, injected sample size can be up to 100 microliters. Follow the instrument manufacturer's recommendation on sample size based on type of sample and level of nitrogen present. To obtain one result, measure each test specimen a minimum of three times and calculate the average detector response.