Sample Preparation Plate For Mass Spectrometry: Fill & Download for Free

There are 4 primary types of procedures relevant to operating a mass spectrometer: Installation, Method Development, Analysis, and Maintenance. Since installation only happens once, let's ignore that one. Maintenance may occur more often than you probably think. I've seen some labs that have to change columns twice per day. It just depends on how many samples you through and how dirty they are. But that's probably not the process people are referring to when they say that MS is time consuming. Analysis is the process people are most familiar with, especially college students. That's where you perform sample prep according to a set of instructions, load the prepared sample into the LC and press "Run" then watch the screen as a bunch of little graphs are drawn out for you. While sample prep can be time consuming depending on the sample and the instrument requirements for compound discrimination, it's a log way from the most time consuming process, method development.So I'll describe generally how the process of method development is performed. I'll use the TSQ Endura™ Triple Quadrupole Mass Spectrometer fitted with a UltiMate™ 3000 Open Sampler XRS System as the example instrument.1. Identify the nature of the compound that you want to analyze. Example include: Small molecule, metabolites, proteins. Because I don't want to spend the rest of the day writing this response, I'm going with "small molecule".2. Decide what kind of analysis you want to perform. Examples include: Qualitative Discovery, Quantitation, or Targeted Screening. Quantitation is the most common type of analysis, so we'll go with that.3. Know your sample and identify the compounds you want to quantify within it. For this example, let's say we're looking at samples of drinking water and we want to measure the amounts of various antibiotics present.4. Devise sample preparation procedure. This is the process of removing things from the sample that will just get in the way and muddy the results. In this case, we will do nothing. The water goes in as-is. But in some cases, this can be time consuming to determine the right procedure which doesn't accidentally remove things you want to keep in.5. Spike your sample. The measurement that a mass spectrometer reports for a given mass at a given time is simply the amount of electrical current which is experienced by the detector when the ionized particles collide with a highly-charged plate of metal. So the intensity value reported is internally consistent for the purposes of comparing with other intensities in the same sample, but it may vary wildly from one instrument to the next. In order to relate that number to a real-world concentration value (usually ng/ml) you have to spike the sample with a known concentration of a known compound. This is referred to as an internal standard. The internal standard you choose should be a distinctly different mass from any of your target compounds, but have as similar of a molecular structure as possible. Therefore, in order to really benefit from the insane accuracy of an instrument such as the Endura, you're going to need an internal standard for every different type of molecule you're looking for, otherwise your margin of error (uncertainty) will far outstrip your mass accuracy. Internal standards are obtained usually one of two ways: buy them or make them. the most common way to make them is to isolate a target compound and then replace one of the hydrogen atoms with deuterium. This will offset the mass by 1 AMU and keep the molecular structure unchanged. the resulting compound is said to be "deuterized".6. Configure the software to control the instrument. The best software for this instrument and analysis type is TraceFinder™. TraceFinder communicates with the instrument via the Instrument Method which is an instrument model-specific application (driver?) included with the instrument itself. You can configure the instrument method one of two ways: trial and error or stand on the shoulders of giants. the pragmatic scientist who doesn't work in academia doesn't have time to play with every possible S-lens value in the world to see which has the best mass resolution. Fortunately, it's highly unlikely that you are performing a truly unique type of analysis. So there is an extremely good chance that a person within academia has already tried all the values and published their results. Google for it, usually pay a few dollars for the academic paper, then use those settings.7. Create a Processing Method. The processing method is essentially a table of values listing each compound and the response for the internal standards and targets at various concentrations. Creating this is probably the most difficult part of the process. You're going to need pure representative samples containing all the targets and standards you are looking for in at least 4 different concentrations. The reason for this is because the software will try to generate a calibration curve for each compound correlating the intensity which each of the concentrations specified. The more known concentrations you can supply, the better the software will be able to fit a curve to it and the more certain you can be of the precision of the instrument. If the instrument is miscalibrated or needs to be serviced, you will see that in the r-squared value, which is a measure of how closely the software was able to fit a curve to the intensity values measured. Government regulations often stipulate minimum r-squared values in order for results to be considered reliable.8. Perform an analysis with a real sample that you are familiar with and expect certain results from just to sanity check your work before handing it off to the high-school grads downstairs to start churning though samples for the next 3 months.

As the question currently stands (“What are the procedures used for cell extraction?”), it is too non-specific to offer anything more than generalities. Specific methods depend on:(1) What is the nature of the starting sample? Bacteria? Animal tissue? Cultured cells? Are they fresh, frozen, or preserved in some way?(2) What is the scale of preparation? Is it a few thousand cells in the well of a 96-well culture plate? Or liters of cells grown in an industrial bioreactor?(3) What is being analyzed? Protein? RNA? An intact organelle?(4) Does the procedure downstream of extraction require intact structure of the protein?(5) What are the compatibility requirements of the analysis procedure? Does the procedure need to be compatible with enzyme activity? Protein:protein interaction? Mass spectrometry?(6) Do you require extraction of proteins from specific cellular compartments (e.g., nucleus, membrane, cytosol)?Generally, extraction procedures rely on either mechanical disruption of the cells or tissue, disruption of the cell membrane or cell wall with chemical extraction reagents such as detergents, or both.Mechanical disruption may include something as simple as multiple freeze-thaw cycles of the sample, or can include more exotic equipment such as a French press or nitrogen-bomb cavitation. In between are mechanical disruptors such a Dounce glass homogenizer, Waring blender, sonicator, rotor-stator homogenizer, mortar and pestle, and others.Chemical reagents often include detergents that can solubilize cell membranes and other structures. The detergents can be non-ionic, such as Triton X-100, ionic such as sodium dodecyl sulfate, or zwitterionic (having both positive and negative charge, but being overall electrically neutral). Generally, non-ionic detergents are considered to be the least disruptive to protein structure, ionic detegents are often denaturing, and zwitterionic detergents are in between. Some detergents are more compatible with some downstream analysis procedures than others, so care should be taken to choose the right one.

Packaging of fast foods contains carcinogensA new study warns that packaging of fast food items contains carcinogens. Polyfluoroalkyl substances (PFASs) are highly persistent chemicals. These chemicals are associated with cancer. They have damaging effects on fetal growth and on the immune system. The reason the food industry is using them is to make food packaging grease-resistant. This is a desirable quality. But other research showed that PFASs can leach into foods, which your system subsequently ingests. CNN has recently reported about this study.Think about this scenario. You are in a hurry to get a quick meal. A hamburger and French fries are your dream and you order it. There is no time for you to think that packaging of fast food items contains carcinogens. But this is exactly what a diverse team of specialists determined. They came from the Silent Spring Institute, Newton, MA and from California Department of Toxic Substances Control, Sacramento, CA. Others came from the Green Science Policy Institute, Berkeley, CA and the Department of Chemistry, University of California at Berkeley, Berkeley, CA. This is not the end. There are 5 more diverse departments that are part of the study and they are listed in this link.The title of their research paper was: “Fluorinated Compounds in U.S. Fast Food Packaging”.How are fluorinated compounds in food packaging materials measured?The researchers measured fluorine in packaging material using particle-induced gamma-ray emission (PIGE) spectroscopy. This method allows measuring fluorine fast and effectively in solid materials like cup materials, wrapping paper, cardboard etc.Findings’ showing that packaging of fast food contains carcinogensResearchers collected 400 samples of food contact paper, paperboard containers and containers for beverages from fast food restaurants. These fast food businesses are all over the US. The researchers used the PIGE spectroscopy method to determine fluorine.First of all, the researchers found that 56% of dessert and bread wrappers contained more than 16 nmol/ cm² of fluorine. They analyzed the positive samples further with more sensitive methods for toxins. Using liquid chromatography/high-resolution mass spectrometry they detected perfluorocarboxylates, perfluorosulfonates, and other known PFASs. And they found other unidentified polyfluorinated compounds. All of these are toxic substances, which you don’t want to ingest.In addition 38% of sandwich and burger wrappers contained PFASs.Finally, 20% of paperboard containers that held French fries showed PFASs.The good news: none of the paper cups showed PFAS contamination.What can you do to protect yourself when packaging of fast food items contains carcinogens?In conclusion, when you go to a fast food place, it is very difficult to get away from exposure to these toxic PFASs. Consequently, your best plan of action is to avoid fast food places altogether. Buy food locally and prepare it at home. The fact that you eat fast foods is already a problem as it is of questionable quality, and the packaging just makes it worse! At home or in restaurants use ceramic plates to place your food on. Also, refrain from processed foods!Packaging Of Fast Food Contains CarcinogensConclusionFast foods are not the healthiest foods as they often contain too many cheap fats, too much salt, many food preservatives and chemicals. But the newest is that it seems like the wrapping that is used to present fast food to you is laced with carcinogens and other toxic chemicals. So be aware that packaging of fast food items contains carcinogens. Therefore your best defense is to do what I did since 2001: buy regular food from a grocery store or farmer’s market and prepare it at home. Also, eat from real porcelain plates with real cutlery. You reduce harmful chemicals in your body and you will remain healthier for longer.Previously published here: packaging of fast food items contains carcinogens.