ICP_Operations_Guide_2016

avoid contamination of the stock standard solution. 3. Perform volumetric pipette solution transfer at room temperature. Aqueous standard solutions stored at ‘lower’ temperature XJMM IBWF B IJHIFS EFOTJUZ 8FJHIU TPMVUJPO USBOTGFST BWPJE UIJT QSPCMFN QSPWJEFE UIF EFOTJUZ PG UIF TUBOEBSE TPMVUJPO JT LOPXO or the concentrations units are in wt./wt. rather than wt./volume. 4. Never use glass pipettes or transfer devices with standard solutions containing HF. Free HF attacks glass but it is sometimes considered safe to use glass when the HF is listed as trace and/or as a complex. However, many fluorinated compounds will attack glass just as readily as free HF. %POU USVTU WPMVNFUSJD QJQFUUF TUBOEBSE TPMVUJPO USBOTGFS 8FJHI UIF BMJRVPU PG UIF TUBOEBSE UBLFO ćJT DBO CF FBTJMZ calculated provided the density of the standard solution is known. There are too many possible pipetting errors to risk a volumetric transfer without checking the accuracy by weighing the aliquot. 6. Uncap your stock standard solutions for the minimum time possible. This is to avoid transpiration concentration of the analytes as well as possible environmental contamination. 7. Replace your stock standard solutions on a regular basis. Regulatory agencies recommend or require at least annual SFQMBDFNFOU 8IZ JT UIJT QSFDBVUJPO UBLFO JO WJFX PG UIF GBDU UIBU UIF WBTU NBKPSJUZ PG JOPSHBOJD TUBOEBSE TPMVUJPOT BSF DIFNJDBMMZ TUBCMF GPS ZFBST ćJT JT EVF UP UIF DIBOHJOH DPODFOUSBUJPO PG UIF TUBOEBSE UISPVHI DPOUBJOFS USBOTQJSBUJPO * BOE UIF possibility of an operator error through general usage (more info)*. A mistake may occur the first time you use the stock standard solution or it may never occur with the probability increasing with use and time. In addition, the transpiration concentration effect occurs whether the standard solution is opened / used or not and increases with use and increased vapor space (transpiration rate is proportional to the ratio of the circumference of the bottle opening to vapor space). Calculations The concentration units for chemical standard solutions used for ICP applications are typically expressed in μg/mL (micrograms per milliliter) or ng/mL (nanograms per milliliter). For example, a 1000 μg/mL solution of Ca +2 contains 1000 micrograms of Ca +2 per each mL of solution and a 1 μg/mL solution of Ca +2 contains 1000 ng of Ca +2 per milliliter of solution. To convert between metric concentration units the following conversions apply:

Scientific Notation Example Units Table 3.1: Mass portion of concentration unit where g = gram

Suffix kilo- (k)

= 1000 g = 0.001 g = 0.000001 g = 0.000000001 g = 0.000000000001 g Decimal Equivalents = 0.001 L = 0.000001 L = 0.000000001 L = 0.000000000001 L Decimal Equivalents

= 10 3 = 10 -3 = 10 -6 = 10 -9 = 10 -12

kilogram (kg) milligram (mg) microgram (μg) nanogram (ng) picogram (pg)

milli- (m) micro- (μ) nano- (n) pico- (p)

Scientific Notation Example Units Table 3.2: Volume portion of concentration unit where L = liter

Suffix milli- (m) micro- (μ) nano- (n) pico- (p)

= 10 -3 = 10 -6 = 10 -9 = 10 -12

milliliter (mL) microliter (μL) nanoliter (nL) picoliter (pL)

The difference between ppm and μg/mL is often confused. A common mistake is to refer to the concentration units in ppm as a short cut (parts per million) when we really mean μg/mL. One ppm is in reality equal to 1 μg/g. In similar fashion ppb (parts per billion) is often equated with ng/mL. One ppb is in reality equal to 1 ng/g. To convert between ppm or ppb to μg/mL or ng/mL the density of the solution must be known. The equation for conversion between wt./wt. and wt./vol. units is: (μg/g) (density in g/mL) = μg/mL and/or (ng/g) (density in g/mL) = ng/mL

* Visit inorganicventures.com/tech/icp-operations/ for additional information from this link