Page:NIOSH Manual of Analytical Methods - 8308.pdf/1

This page needs to be proofread.

FLUORIDE in urine 8308

F-

MW: 19.00

CAS: 16984-48-8

RTECS: LM6290000

METHOD: 8308, Issue 2 EVALUATION: FULL Issue 1: 15 February 1984 Issue 2: 15 August 1994

BIOLOGICAL INDICATOR OF:

exposure to inorganic fluorides [1,2].

SYNONYMS: none.

SAMPLING

SPECIMEN:

urine, pre-and post-shift

VOLUME:

50 mL in chemically clean polyethylene bottles

PRESERVATIVE:

0.2 g EDTA added to bottles before collection

SHIPMENT:

in insulated containers using bagged refrigerant

SAMPLE STABILITY:

2 weeks @ 4 C, longer if frozen

CONTROLS:

collect 3 sets of specimens from unexposed workers (pre- and post-shift)

MEASUREMENT

TECHNIQUE:

ION SELECTIVE ELECTRODE (ISE)

ANALYTE:

fluoride ion (F ^-)

DILUTION:

mix equal volumes of urine with TISAB

CALIBRATION:

solutions of sodium fluoride in water

QUALITY CONTROL:

spiked urine pools; correct for creatinine content

RANGE:

1 to 100 mg/L urine

ESTIMATED LOD:

0.1 mg/L urine

RECOVERY:

0.95 [3]

PRECISION (Sr):

0.04

ACCURACY:

± 23.6%

APPLICABILITY:

Any fluorine-containing substances that can be metabolized to fluoride (F ) can be monitored using this procedure. Inorganic compounds of fluoride can be absorbed by the body resulting in the excretion of fluoride ions as sodium fluoride. Dietary and domestic water sources of fluoride must be considered, as well as dental treatments.

INTERFERENCES:

Hydroxide, the only positive interference, is eliminated by use of the buffer. Negative interferences from complexation of fluoride by cations, such as calcium, are minimized by EDTA preservative and the high ionic strength buf fer.

OTHER METHODS:

This method is P&CAM 114 [4] in a revised format. Other methods that have been used are those described in the NIOSH criteria documents on inorganic fluorides [1] and hydrogen fluoride [2].