Tuesday, July 16, 2013

Hydrogen Sulfide in Beer and Wine


Summer is here.  And what activity better exemplifies summer than sitting by the pool, taking in the sun’s bounty, and enjoying an ice cold beer? However, if that beer smells faintly of rotten eggs or has a dreaded “skunky” flavor it can ruin an otherwise idyllic afternoon.

So what causes these undesirable off flavors? During fermentation the yeast which converts simple sugars into alcohol also naturally produce some hydrogen sulfide (H2S). Low levels of H2S are actually desirable and give the beer complex, defining flavor characteristics. However at higher concentrations H2S is responsible for the off-putting rotten egg smell, and the interaction of H2S with the hops used in the brewing process are responsible for the skunky odor in bad beer.  Excess H2S can be a symptom of unhealthy yeast, microbial infection, improper oxygen levels during fermentation, or a myriad of other root causes.

Due to the volatility of H2S (b.p. = -60°C), one effective method for testing the concentration of dissolved H2S is to test the headspace above the liquid. If the temperature and accumulation time are well controlled, then the concentration of H2S in the headspace will be proportional to the concentration of H2S dissolved in the sample. Brewers have sophisticated sensors in their fermentation tanks to monitor the H2S concentration during production, but as anyone who has bought an off case of beer knows, bad beer can sometimes make it into the bottle.

Figure 1: Apparatus Setup for determination of H2S in beer by Jerome®J605

Arizona Instrument LLC has a solution for the determination of H2S in bottled beer using the Jerome® J605 Hydrogen Sulfide Analyzer. The method can be run in under seven  minutes and can be used to determine H2S concentration in beer as low as 5 parts per billion (ppb). No hazardous materials are required for testing. The instrument response over the range investigated was linear with respect to concentration.

 To run a test, an Erlenmeyer vacuum flask is connected to a Jerome® J605 Hydrogen Sulfide Analyzer by tygon or other suitably sized inert tubing. A full bottle of beer is poured into an Erlenmeyer flask and allowed to stir for 5 minutes. The instrument is placed in auto range and auto sample, sampling the head-space above the beer every 2 minutes.  The instrument is allowed to sample for 30 minutes, and the results are then summed.

James A. Moore, Garrett M. Rowe

Research Group, Arizona Instrument LLC

For more information contact us at (800)528-7411 | sales@azic.com | www.azic.com
For a full copy of the method and accompanying data contact Arizona Instrument LLC.
For a printable version visit www.azic.com

Wednesday, April 17, 2013

How does Atomic Fluorescence Spectroscopy measure up?

Jerome® J505 Portable Atomic Fluorescence Spectroscopy
Mercury Vapor Analyzer

Whether it is fluorescent lighting, dental fillings, antique switches, gold mining or thermometers, the element mercury (Hg) is present in the world we live.  Many of the mercury containing products give us comfort, are used to provide us with information, and even allow us to control our environment.  While these products are safe, they could potentially expose people to a plethora of toxic compounds if an accident should occur.   Symptoms of mercury exposure include seizures, memory loss, and in some cases, death.  Because of these risks, several guidelines and regulations have been developed that limit the amount of mercury people can be exposed to, and special methods are required for cleaning up mercury if an accident should occur.  Currently the time weighted average limit for mercury varies depending on regulating agency.  For OSHA, the limit is 0.1mg/m3*; NIOSH sets the limit at 0.05mg/m3*; and the ACGIH has a limit of 0.025mg/m3*.  Since mercury vapor is not something people can see, how do they determine their amount of exposure?  Arizona Instrument, LLC manufactures the J505 Atomic Fluorescence Analyzer; a handheld atomic fluorescence spectrophotometer that measures the concentration of mercury in air.  The lower detection limit of this instrument is 50ng/m3 (0.000050mg/m3), and it can detect as high as 0.5mg/m3.  These detection limits exceed the current industrial exposure limits, as well as clean-up levels for public facilities.

Atomic Fluorescence Spectroscopy (AFS)
When an atom is excited by an input of energy, one of its electrons transitions from a stable ground state to an unstable excited state.  Once the source of energy is removed, the electron returns to its ground state and the absorbed energy is emitted as a photon (light).  This process is called fluorescence.  Often the amount of energy given off is not the same as the energy going in.  This is not the case for mercury, which makes it special.  When the energy required to excite an electron is the same energy as the photon it gives off when it returns to its ground state, it is called resonance fluorescence, and is easily detectable using AFS.  The J505 instrument uses a mercury lamp to excite the mercury atoms at the 254nm wavelength, and then uses a detector to measure the emission of the photons, at the same wavelength, as the electrons return to their stable ground states. Because AFS measures the emission of photons, this technique does not have interferences, such as hydrocarbons, hydrogen sulfide, and ammonia, which are often problematic for traditional detection methods.   The specifications for the J505 Atomic Fluorescence Analyzer are below.  
Atomic Fluorescence Spectroscopy should not be confused with Atomic Absorption Spectroscopy (AAS).  In AAS, a light source of known wavelength and intensity is passed through a sample of interest. Some of the energy of the source light is absorbed by the sample as it energizes electrons in the material from the ground state to an excited state. A detector is placed at the end of the pathway to determine how much of the energy passed through. The difference between the energy of the source light and the energy of the light that arrives at the detector is directly proportional to the concentration of analyte in the sample.  One of the drawbacks of this technique is that there are a number of other common molecules that can absorb energy at the same wavelength as mercury.  To compensate for these unwanted absorptions, manufacturers use a variety of filtering techniques to limit background interference. While these filtration principles are sound, they come at the cost of a more complicated and bulkier instrument. Further, AAS can also have physical limitations that may limit low level sensitivity. At very low concentrations, the amount of absorbed light, when compared to the intensity of the incident light source, can become indistinguishable from electronic noise, making detection at these levels more challenging.
* These TWA averages are dependent on time.  For more information on exposure limits  please visit each respective website.


J505 Specifications                         
Test Mode                        Units:
Standard                                      Range
50 to 500,000
.05 to 500
0.00005  to 0.50000

(0.05 µg/m3 ± 0.033 µg/m3 to 500 µg/m3 ± 40 µg/m3)
Quick                                             Range
100 to 500,000
0.1 to 500
0.0001 to 0.500
Search                                          Range
100 to 500,000
0.1 to 500
0.0001 to 0.500
Typical Test Time                Standard
28 seconds
16 seconds
8 seconds for first reading then continuous 1 second updates
Power requirements
Internal battery (NiMH) with 10+ hours of operation
12VDC power adapter runs on 100-240VAC, 0.8A, 50-60Hz
Battery charges in 3 hours or less
(Note: Battery will not charge if battery temperature > 40 °C)
Operating environment
5 to 45 °C, non-condensing, non-explosive
12in L x 6.2in W x 8.4in H
(30.5cm L x 15.7cm W x 21.3cm H)
6.5 pounds (3.0 kilograms)
3.5 inch (9 cm) color LCD display.
High brightness backlight
Unattended Autosample
Available in intervals of 1, 2, 5, 10, 15, 20, 30, 45, 60, 90 or 120 minutes
Data storage capacity
Up to 10,000 test results
100 test sites
USB port located on rear of instrument
Test results and calculations saved to USB flash drive
Menu navigation, text entry, and softkey operation with optional USB Keyboard
Power adapter marked with UL and TUV

Accuracy and Precision (Standard mode):

Gas Level
Precision (RSD)
0.3 µg/m3
± 15%         
1 µg/m3
± 10%         
25 µg/m3
± 10%       
100 µg/m3
± 10%            

James Moore, Chemist
Arizona Instrument LLC
sales@azic.com | www.azic.com

Friday, April 6, 2012

NEW! Portable Atomic Fluorescence Spectroscopy Mercury Vapor Analyzer



The NEW! Jerome® J505 Mercury Vapor Analyzer is a portable fluorescence spectroscopy analyzer, which allows the detection cell to be simpler, smaller, lighter weight and more durable than competing spectroscopy instruments. The highly efficient optical cell requires less flow to purge the system, allowing the J505 to run at a lower flow rate minimizing sample dilution as found in competing spectroscopy instruments.
More Information

800.528.7411 | www.azic.com
Meets EPA & ATSDR Cleanup Levels
Flexible Data Handling
10+ Hour Battery Life
Two Independently Adjustable High Limit Alarms
Programmable Auto Sampling Mode
3 Units of Measurement
Color Display with Easy to Use Menu System
USB Keyboard Option
Data Logging
Resolution: 0.01 µg/m3
Detection Range: 0.05 - 500 µg/m3
Data Storage Capacity: Up to 10,000 test results

Ambient Air Analysis
Clean Up Compliance
Detection Compliance
Leak Detection
Quality Control
Scrubber Efficiency Testing

Tuesday, January 10, 2012

Mercury Poisoning

Mercury Poisoning

In December 2011, EPA issued the first national standards for mercury pollution from power plants. MATS are the first national standards to protect American families from power plant emissions of mercury and toxic air pollution like arsenic, acid gas, nickel, selenium, and cyanide. The standards will slash emissions of these dangerous pollutants by relying on widely available, proven pollution controls that are already in use at more than half of the nation's coal-fired power plants. Read the press release | Learn more about these actions | Read the final rule (PDF).

Mercury poisoning (also known as hydrargyria or mercurialism) is a disease caused by exposure to mercury or its compounds. Mercury (chemical symbol Hg) is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses. Its zero oxidation state Hg0 exists as vapor or as liquid metal, its mercurous state Hg+ exists as inorganic salts, and its mercuric state Hg2+ may form either inorganic salts or organ mercury compounds; the three groups vary in effects. Toxic effects include damage to the brain, kidney, and lungs.  Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease.

Symptoms of mercury poisoning typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure.

Mercury Toxicity Limits

Regulating agency
Regulated activity
Type of mercury compound
Type of limit
Occupational Safety and Health Administration
occupational exposure
elemental mercury
Ceiling (not to exceed)
0.1 mg/m³
Occupational Safety and Health Administration
occupational exposure
organic mercury
Ceiling (not to exceed)
0.05 mg/m³
Food and Drug Administration
inorganic mercury
Maximum allowable concentration
2 ppb (0.002 mg/L)
Food and Drug Administration
Maximum allowable concentration
1 ppm (1 mg/L)
Environmental Protection Agency
inorganic mercury
Maximum contaminant level
2 ppb (0.002 mg/L)

Monday, January 9, 2012

New Employee Annoucement

Arizona Instrument LLC welcomes Idonia Mancillas to the Marketing Department! Idonia has joined us from the Customer Service Department. She has been doing a phenomenal job for our company in the service department for nearly 5 years, and will be a huge asset to the Marketing Department.

Her official title will be Marketing Specialist, and she will be handling our tradeshow shipping coordination, sales literature requests and lead entry. We are so excited to have her on the Marketing Team!

Shari Moore
Marketing Manager
Arizona Instrument LLC