The IV Line News from the Lab
Inorganic Ventures' E-newsletter  •  November 2003  •  ivstandards.com
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In this issue...
 News from the Lab  Articles Online
 Analytical Quick Tip  Joke of the Month
 Choosing the Right Plastic

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News from the Lab
Helping Toys For Tots

Helping Toys For Tots
Every order helps a child in need
During the months of November and December, Inorganic Ventures is donating a percentage of every order to the Toys For Tots foundation, providing needy children with toys this holiday season.

2004 Winter Conference
Educate your lab...
Join Dr. Paul Gaines as he presents two lectures at the 2004 Winter Conference on Plasma Spectroscopy. Lecture attendees will receive a free "Spectroscopic Elements" workbook.

Analytical Quick Tip

Do not use a silicone-based grease on the ground glass joints of your volumetric glassware. The grease will migrate and cause poor drainage (droplets will remain).

Choosing the Right Plastic

Whenever possible, the analyst should attempt to use plastics for sample collection, storage, preparation, and measurement. Their major disadvantage is the inability to be used for high temperature operations, such as ashing or fusion. The table below shows a summary of the physical properties of some common plastics.

Physical Properties of Common Plastics
Physical Properties of Common Plastics

FEP  (FLUORINATEDETHYLENEPROPYLENE)
PFA  (PERFLUOROALKOXY)
FLEP  (FLUORINATED HIGH-DENSITY POLYETHLYENE)
PMP  (POLYMETHYLPENTENE)
PP  (POLYPROPYLENE)
HDPE  (HIGH-DENSITY POLYETHYLENE)
LDPE  (LOW-DENSITY POLYETHYLENE)

The most popular plastics are PFA and HDPE/LDPE.

PFA has excellent properties, allowing for use in acid digestions up to 250 °C. Typically, PFA is used for acid digestions using either HF, HNO3 or HCl, alone or in combination. The use of higher boiling acids such as H2SO4 and H3PO4 have been reported in PFA, but great care must be taken not to exceed the 250 °C maximum operating temperature. PFA is commonly used in the construction of microwave digestion vessels. Microwave digestions using the higher boiling acids should not be attempted. Digestions using HCLO4 should never be performed in plastics of any kind.

LDPE or HDPE bottles are typically used for containment of the sample digestate after dilution with water. These bottles can withstand solutions of HNO3 that are 10% v/v and lower over extended periods of time (i.e. - years). The caps used for the LDPE and HDPE bottles are made of PP, which is more rigid than the polyethylene and well-suited for its purpose. Unfortunately, the PP cap is not as clean as the PE bottle.

The above passage was taken from Reliable Measurements: Container Material Properties. Read the full guide here.

Articles Online  more articles

ICP Quality Issues
Part two of our ICP Operations guide discusses the most important quality issues with respect to multi-element chemical standards.

Analytical Tips For Tin
Dr. Gaines suggests the best lines for interference-free tin analyses.

Analyzing Silicone Oils
Dr. Gaines offers advice and preparation tips for the analysis of silicone oils.

Joke of the Month  more humor

Isaac Asimov once said that if you want to find a true chemist, ask the individual to discuss the following words:

- mole
- unionized

As he so eloquently put it, "If he starts talking about furry animals and organized labor, keep walking."
Element of the Month
Tin

Analytical Periodic Table

Storage & Handling:  Keep tightly sealed when not in use. Store and use at 20 ± 4°C. Do not pipet from container. Do not return portions removed for pipetting to container.

Chemical Compatibility:  Soluble in HCl and dilute HF / HNO3. Avoid neutral to basic media. Unstable at ppm levels with metals that would pull F- away (i.e. - do not mix with Alkaline or Rare Earths or high levels of transition elements unless they are fluorinated). Stable with most inorganic anions, provided it is in the following chemical form: Sn(OH)xFy2-.

Stability:  2-100 ppb levels stable (alone or mixed with all other metals that are at comparable levels) as the Sn(OH)xFy2- for 1 year in 1% HNO3 / LDPE container. 1-10,000 ppm single element solutions as the Sn(OH)xFy2- are chemically stable for years in 2-5% HNO3 / trace HF in a LDPE container.

Sn Containing Samples (Preparation & Solution):  Metal (soluble in HF / HNO3 or HCl); Oxides - SnO (soluble in HCl), SnO2 - very resistant to all acids including HF (fusion with equal parts of Na2CO3 and S is soluble in water or dilute acids as the thiostannate); Alloys (treat first 0.1 g with 10 mL conc. H2SO4 to boiling until the alloy disintegrates and nearly all of the sulfuric acid is expelled. Then add 100 mL O2 free water and 50 mL of conc HCl or transfer to a plastic container and add 1 mL HF, in either case, warming gently to bring about solution); Organic Matrices (volatility and precipitation of the insoluble stannic oxide are problems -- because these preparations are prone to error, we recommend you contact our technical staff at ivtech@ivstandards.com or (800) 569-6799 and we'll provide you with the necessary data for your specific sample type).

Excerpt from Inorganic Venture's Analytical Periodic Table: Includes detailed analytical data for more than 70 elements.
 
Elemental Wordplay
Rearrange the elemental symbols to solve the riddle. Clues appear in quotes.

November's riddle...

You might be arrested if you leave home without this "textile" made from...

    - Oxygen
    - Einsteinium
    - Thorium
    - and Chlorine?

(answer at bottom of page)
**********************************************************************************************************
 Wordplay answer:  Clothes (Cl, O, Th, Es)
 The IV Line · News from the Lab  · November 2003 (volume 4)
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