Quite often, it happens that a laboratory experiment does not yield the desired result, and it becomes a tedious task to find where the error has occurred. Volumetric calibration, concentration of chemicals used, purity of solvents and reagents, minute changes in simulation environments and a combination of all the above may play a significant role in yielding productive results in an experiment.
A thorough knowledge of the lab procedures like equipment calibration, classification of chemicals based on various aspects and an understanding of different shelf lives of chemicals and reagents may do away with errors and inaccuracy in lab results.The chemicals used in laboratories should be chosen wisely based on the intended accuracy scale and their purpose. If the chemicals used in labs are not rightly chosen, it could result in adverse financial implications and the loss of many years of scientific struggle .Further, the erred output of a biomedical lab and misinterpreted diagnosis may even put human lives at risk. Erred readings of a forensic lab and Industrial lab output prior to the manufacture of a product have impactful consequences on human life.
Chemicals used in laboratories are usually categorised according to the specific field of science and research, the lab is associated.A good understanding of the purity grade classification, hazard level classification and the wider, more vague purpose level classification will help any experimenter to find the right chemical most suited for their application. A general trend in many laboratories is to categorize chemicals as organic and inorganic,reagents and active agents and solvents and solutes.This classification will help the lab administrator to shelf the chemicals in the lab in a more organized and efficiently aesthetic way,but it is the classification based on grades of purity of chemicals which determine the precision of lab output. For instance, just assume the use of a lower grade industrial level activated charcoal as an absorption medium for the chromatographic analysis of a solvent.The adsorption levels of lower grade activated charcoal will differ considerably with a higher grade of adsorption medium causing drastic consequences in the final analysis.
Based on purity generally chemicals are categorized into seven grades. Manufacturers of chemicals supply the chemicals and reagents based on these grades and ensure that the chemicals have met all regulatory and compliance standards for their intended use.On the other side those who endeavor in any experiment must have a clear understanding of what is the desired output and the grade of chemical purity opted to get the result.Lab procedures like HPLC (High Performance Liquid Chromatography ) require chemicals with the highest purity levels for analysis as the slightest change will spoil the precision scales.Experiments demanding more precision and accuracy require chemicals of matching purity levels.
The ACS grade meets or exceeds purity standards set by American Chemical Society(ACS).Chemicals of this grade are the purest and are usually used for medical,food and pharmacological experiments.Chemicals exceeding purity levels of more than 95 percent are the best for precise analytical experiments.The reagent grade of chemicals are generally equal to ACS grade with 95 percent purity and is acceptable for food,drug or medical use.These can also be used for lab analytical experiments. The USP grade ( United States Pharmacopeia) suggests a purity grade acceptable for food,drug and medicinal use.Care must be taken when using USP grade chemicals to ensure the methodology for the experiment is appropriate for the result. The NF grade(National Formulatory) grade chemicals are mostly suggested for biological drug substances as it confirms to public pharmacopeial standards. The standards for different purposes should be closely followed as it enlists each grade class vividly for various purposes ranging from medical labs to dietary supplements.
Laboratory grade chemicals are popularly used for educational applications.This grade of chemical purity is good for teaching and training basic chemistry in labs.As the amount of impurity is not clear these should not be used for analytical experiments demanding precision.This grade should not be used for pharma and medical labs.Chemicals with a purity level of PG( Purified Grade) are not good for food medical or drug use of any kind.Industrial or technical grade is the least purest of chemicals and as the name suggests are used by factories in manufacturing processes.When ordering the chemicals for your lab a mindful approach to classify them according to the GHS hazard levels is highly appreciated.The GHS guidelines are equally helpful for suppliers, persons undertaking business and undertakings, workers and other persons involved with hazardous chemicals. The internationally followed GHS document known as the purple book includes harmonised criteria for the classification of physical hazards (e.g. flammable liquids), health hazards (e.g. carcinogens and allergens) and environmental hazards (e.g. aquatic toxicity).The lab must have adequate provision to dispose of hazardous chemicals and by products in an environmentally responsible way.
Choosing the right chemicals for your lab also depends on the purpose of the laboratory. The chemicals used in a Forensic lab are not the same as the one which is used in a Pharmacological lab. It is a recommended practice that the laboratories limit the storage of chemicals only to the labs’ intended purpose. Whenever possible, substitutes for volatile chemicals must be used to reduce overheads unless the process absolutely demands it. Similarly, potently toxic chemicals should be replaced with less harmful ones. Chemical stocks must be rationally maintained considering their shelf lives, volatility, frequency of use and the quantity permitted by the authorities for scientific, educational and research storage. Stocking chemicals with low shelf life and infrequent usage will certainly cause wastage which could be avoided if taken care of.
A lab manager must be aware of these chemical classifications to opt for the most suited chemicals for the lab, to check in maximum productivity and reduce miscellaneous costs.
