In this issue:

News from the Lab  Articles Online  Analytical Quick Tip  IV Line Humor  Facts About Nitric Acid

Enjoy the IV Line?  tell a friend »

NEW! Isotopic Standards
User-driven development is the cornerstone of our manufacturing efforts. Based on your feedback, we've assembled a robust new line of Isotopic Standards.

All isotopic solutions are guaranteed in stock, so they'll leave our facility the day you place your order. View our product listings for details.

Helping Children
It's that time of year and once again, we're happy to donate a percentage of every order to Marine Toys For Tots, a nonprofit foundation that provides for underprivileged children. We thank you for your support.

Uncap your stock standard solutions for the least amount of time possible. This is to avoid transpiration concentration of the analytes as well as possible environmental contamination.

• The highest valence of nitrogen is +5. This is the valence of nitrogen in nitric acid. All three N-O bonds are sp² hybrid and the NO_3- molecule is planar and symmetrical.

• The oxidizing ability of nitric acid decreases (reduction potential decreases) as the concentration decreases. Below 2M, the oxidizing ability is nearly eliminated.
  
  
• Nitric acid undergoes both one and three electron changes. The one electron change is observed when concentrated. In comparison, the 3 electron change is observed when dilute. The presence of brown fumes is indicative of reactions going by 1 electron.
  
       (a)  H₃O⁺ + HNO₃ + e^-1    NO₂ (brown) + 2H₂O : Concentrated
  
       (b)  3H₃O⁺ + HNO₃ + 3e^-1    NO (clear) + 5H₂O : Dilute
  
  
• Nitrate is generally considered to be a 'poor ligand' in that it's coordination ability is not enough to keep hydrolysis from occurring. This statement may be contradicted in certain inorganic text books.
  
  
• The most common 'good ligands' used in combination with nitric acid are HCl, HF, and tartaric acid (for Sb). If nitric acid was a better ligand, these additional acids would not be needed.
  
  
• Concentrations of HNO₃ between 65% and 69% are known as 'concentrated'; concentrations greater than 69.2% are known as 'fuming nitric acid'.
  
  
• 100% nitric acid is light and heat sensitive and boils at 84 °C. ‘Concentrated' nitric acid boils as an azeotrope (with water at 69.2% HNO₃) at a temperature of 121.8 °C. The distilled HNO₃ (trace metals grade) should be at the 69.2% concentration level.
  
  
• Check with your manufacturer of doubly distilled nitric acid to determine if the container in which it is packaged is nitric acid leached prior to use. In the case of Teflon containers, the container material is generally assumed to be pure.
  
  
• PTFE and PFA Teflon can be heated with concentrated nitric acid, even at high pressures or with combinations such as nitric + HCl, nitric + HF, and nitric + H₂O₂.
  
  
• Nitric acid is not a strong enough oxidizing agent by itself to convert organic molecules to CO₂ and H₂O (completely oxidize).

Exceprt from Inorganic Ventures' Reliable Measurements Guide.

Articles Online  more articles »

Flexible Expiration Dates?
Is it possible to stretch a standard's expiration date beyond a year? Get the science behind the debate.

ICP Operations Guide (complete)
A clear 16-part online guide intended for anyone preparing samples and standards for measurement using ICP. Topics cover many day-to-day tasks required by all operators.

Reliable Measurements: A Guidebook for Trace Analysts (complete)
An essential 17-part online guide for chemical analysts. Topics cover all phases of sample collection, preparation, measurement, and data analysis.

IV Line Humor  more humor »

Q: Why does hamburger yield lower energy than steak?

A: Because it's in the ground state.