[Tagher]

Hi,
I'm a forensic scientist and I'm new to my lab and I was looking at the reagents we use for chemical testing and I'm a little concerned that no one in my lab knows the shelf life from manufacture or expiration once opened of the chemicals we use. I have been looking up as best I can this info on the net, but some of it is really hard to locate. I should also mention that my background is bio, not chem so I'm doing the best I can. Two of the reagents I can't find a shelf life for are O-dianisidine tetrazotized (fast blue b) and disodium salt alpha naphthyl phosphate or 1-naphthyl phosphate disodium salt hydrate- Both of these reagents we use to make our acid phosphatase reagent.  And I can't find the info on the manufacturer's website. I can email them, but thought it might be easier to ask here first. And I hope this is in the right forum section.
Thanks

[Jasim]

Your lab should have guidelines regarding expiration of chemicals. If it doesn't, then I suggest someone take the initiative to make some and make them official.

Here are some general guidelines we use in the analytical lab (should be similar work to a forensic lab if you are doing GC, LC...etc.):

Expiration of high-grade water is one month after opening bottle.
Exp. of solid reagents is 3 years after opening bottle, unless otherwise noted.
Exp. of organic solvents is 1 year after opening bottle, unless otherwise noted.
Exp. of in-lab mixed chemicals (meaning you mix them) should be 1 month or 3months to 1 year for pure organics.

Exceptions are for reagents that degrade, especially reagents that become dangerous upon degradation (e.g. peroxide formers). Peroxide formers should be tested every 3 months and discarded at the first sign of peroxide formation (test immediately before using a peroxide former in a distillation).

Check the MSDS from the manufacturer for any specific guidelines that would over-rule the above general guidelines. I'll list some MSDS sites here:

http://www.fishersci.com/ecomm/servlet/msdssearchhome?showMSDSSearch=Y&storeId=10652
https://uk.vwr.com/app/GenericPage?page=/search/msds.jsp?en_GB_msds
http://www.merckmillipore.com/?RedirectedFrom=http://www.merck-chemicals.com&ShowHomeLayer=true
http://www.avantormaterials.com/search.aspx?searchtype=msds
http://www.sigmaaldrich.com/safety-center.html
http://www.emdmillipore.com/certificates-of-analysis-instructions/c_l4Gb.s1OdIwAAAEkjupreX3m

[Tagher]

Yea those are the timelines I've always gone by at my chemistry lab, however this lab is accredited by iso 17025 only. The prob I've found/read w this ISo is that it only covers expiration times with things like calibrations. It doesn't specifically have written in that chemicals used need expiration dates, hence how the lab somehow has gotten away w not having proper expiration dates in over six years, even w FQS coming to reaccredit every two yrs. I believe the iso that requires expiration dates specifically is listed in article 34 and iso 9001. I just needed some confirmation. I am appalled at how old these things are, for example, I found the fast blue b zinc complex cl 37235 is from 1983. Everything I can find on it says shelf life of 1-3 yrs. and that's before being opened. It is just very disconcerting. I'm recommending they order many of the reagents, I just hope the city will pony up the money wo a huge fight.

[crosemeyer]

If it doesn't have an expiration date, and it still works, what is the problem?

Prove they work with standards, and you should be all good.

[orgopete]

I am not a forensic scientist, so I have no business even commenting and my opinions are without value.

I don't know the protocols of the tests being performed, so I don't know the results. I would imagine that if a standard curve were created for a specific test, the results should be as valid as that comparison. The standard curve should prove how good this analysis was performed and the specific response should reflect on how good the reagent was. That is, if an analyte gave a specific absorbance at a specific concentration, an expired standard should perform as though less standard were used.

I am just guessing some standards may be more stable than others. Sodium chloride from pre-industrial revolution days may be just as pure as the day it was prepared and biological reagents may have short shelf lives. If it were me, I'd try running some of the tests to see if there is a notable change in the results. This sounds like you have a topic for forensic science to study.

[rjb]

Tagher,

You make a very interesting and important point and I think it is commendable that you are taking the 'bull by the horns' so to speak - Good Luck!

Common sense dictates that chemicals should be ordered in quantities no greater than will be required for the foreseeable future (1 year or less makes sense in your environment), so using fast blue from 1983 is a bit ridiculous in my opinion. If we're honest, I suspect that all of the chemicals in questions are perfectly viable and will produce the results expected of them. I suspect that you run +ve controls to show that your AP is functioning as expected and that all AP+ve stains are confirmed under a microscope to determine no. of sperm heads etc. Nevertheless, my view is that you should ditch everything that you use over 3 years old as a matter of course and replace with appropriate (not Kg's!) quantities of fresh ASAP... Perhaps most of the chemicals involved do not 'go off' and will in no way affect your results, but it's as much about perceptions as anything... It doesn't take a genius to see that the fact you may be using something purchased in 1983 does not reflect well on your lab and will affect the jury's impressions of levels of scientific expertise and professionalism, much in the way as turning up for court in a decrepit/stained/dirty/torn suit will affect impressions of your personal expertise...

This (awful article) may be food for thought -http://www.dmagazine.com/Home/D_Magazine/2011/September/Bad_Blood_at_the_Dallas_County_Crime_Lab.aspx

Not relevant, but just out of interest, are you working in the US or Europe?

Kind Regards

R

[voidSetup]

I work as an analytical chemist in a pharmaceutical lab.  Our SOP's dictate that common solvents (MeCN, methanol, etc.), and common salts are good for 10 years after the date opened.  Peroxidizables are good for 6 months.  Of course both of these are unless otherwise stated by the manufacturer.

Prepared solutions such as mobile phases or diluents are good for 1 month, unless solution stability studies have shown otherwise.

[Jasim]

A good point was brought up in a couple of the posts above. If good quality assurance is built into the methods and protocols, then many chemicals can be use beyond their standard shelf-life. So long as you can point to good data to backup a claim that the reagent is still suitable for the specific use, then there shouldn't be a problem.

Given that this is a forensic lab issues may arise if such claims are contested in court. Good documentation, good data, and sound scientific judgement is necessary.