Phosphonates
Phosphonates
Page 4 of 6
Phosphonates_PP_Other_PUV_Eng_Ody.fm
Interferences
The interference levels will decrease as the sample size increases. For example,
copper does not interfere at or below 100 mg/L for a 5.00 mL sample. If the
sample volume is increased to 10 mL, copper will begin to interfere above
50 mg/L.
Sample Collection, Storage, and Preservation
Collect samples in acid-cleaned (1:1 HCl, Cat. No. 884-49) plastic or glass bottles
that have been rinsed with distilled water. Do not use a commercial detergent. If
prompt analysis is impossible, preserve the sample by adjusting to pH 2 or less
with Sulfuric Acid (about 2 mL per liter) (Cat. No. 979-49). Store at 4 °C (39 °F).
Preserved samples may be stored up to 24 hours. Correct the test result for
volume additions; see Section 3.1.3 Correcting for Volume Additions on page 29.
Table 3 Interfering Substances and Suggested Treatments
Interfering Substance Interference Levels and Treatments
Aluminum 100 mg/L
Arsenate Interferes at all levels
Benzotriazole 10 mg/L
Bicarbonate 1000 mg/L
Bromide 100 mg/L
Calcium 5000 mg/L
CDTA 100 mg/L
Chloride 5000 mg/L
Chromate 100 mg/L
Copper 100 mg/L
Cyanide 100 mg/L (Increase the UV digestion to 30 minutes.)
Diethanoldithiocarbamate 50 mg/L
EDTA 100 mg/L
Iron 200 mg/L
Nitrate 200 mg/L
NTA 250 mg/L
Orthophosphate 15 mg/L
Phosphites and
organophosphorus
compounds
React quantitatively. Meta- and polyphosphates do not interfere.
Silica 500 mg/L
Silicate 100 mg/L
Sulfate 2000 mg/L
Sulfide Interferes at all levels
Sulfite 100 mg/L
Thiourea 10 mg/L
Highly buffered samples or
extreme sample pH
May exceed the buffering capacity of the reagents and require sample pretreatment.
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