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BARNSTEAD’S TECHNICAL APPLICATION BULLETIN T

BULLETIN 0011

. V

ALIDATIONOF Trace Metals, Anions and Cations

A

. NANO

PURE ®

DI

AMOND

B

.

™

UV W

ATER

M

odern analytical instrumentation allows for thedetermination of metals and ions in water at the lowparts per trillion level. At these low levels, extremecare must be taken to ensure that a sample is not contam- inated during sampling, storage or handling. Water from a NANOpure DIamond UV was analyzed using validatedtrace element techniques in a clean room environment.Inductively coupled plasma – mass spectrometry (ICP-MS) and ion chromatography (IC) were used to analyze the water for trace metal or ion contamination. The resultsindicate that the water is below the limit of detection for allcalibrated compounds, which include 13 major anions and cations and 68 trace metals. was initially purged with 10 L of water to condition it and then subsequently purged with 0.5 L of water prior to sampling the water for analysis. All sampling was performed using cleantechniques with acid-washed bottles. Anions and cationswere analyzed using a Dionex Model 500DX ion chromato- graph with dual columns and dual conductivity detectors. Trace metals were analyzed using ICP-MS with a quadrupoledetector for the lowest limits of detection. Because of inter-ferences using ICP-MS, silica was analyzed by a wet chemi- cal spectrophotometric method in which dissolved silica reacts with molybdate to form a colored complex.

R

ESULTS

M

ETHODS

Ω -cm is theoretically pure, in reality it may still containparts per trillion levels of various ionic species and thereforeneeds to be validated with the highest-sensitivity instrumenta- tion. A NANOpure DIamond UV (Model # D11911) was set up with an Organic Free Cartridge (Model # D50280 forreverse osmosis or distillation feed and # D50281 for deion-ized feed) in a clean room at Balazs Analytical Laboratory in Sunnyvale, CA. The water feeding the DIamond was from the laboratory’s central water system and exceeded theDIamond’s minimum feed requirements. The pack waspurged of air with the “air purge” menu selection and allowedto recirculate for several days to condition the cartridge pack and system components. A new 0.2 micron hollow-fiber, cel-lulose-acetate final filter was also installed. This filter is animportant component of the system since it removes submi- cron particles and bacteria from the product water. The filter All of the calibrated compounds were below the limit of detection in the DIamond UV product water. The results are reported as

T

ABLE

1

Anions by Ion Chromatography

Anion Result (ppb) Fluorine (F-) <0.1 Chloride (Cl-) <0.02 Nitrite (NO2-)<0.02 Bromide (Br-)<0.02 Nitrate (NO3-) <0.02 Phosphate (HPO42-) <0.02 Sulfate (SO42-)<0.05Results reported as T ABLE

2

Cations by Ion Chromatography

Cation Result (ppb) See Table 3 on next page.