Sample Preparation
The fundamental principle for chemical analysis has to take a step by step procedure from sample collection, preparation and later analysis, sample preparation stage takes up most of the time given its tedious range of activities involved. Sample preparation depends on each given chemical and its nature and effect on the environment. The primary purpose of sample preparation is to homogenize, increase or decrease analyte concentration, remove contaminants, alter the sample phase, the liberation of analyte from the sample matrix and also modify its structure.
The techniques for sample preparation depend on specific factors of the sample under study, the factors to be considered include chemical properties of the sample, the instruments to be used and the matrix of the sample.
Sample preparation methods for metals can be done based on two factors, for liquid metals, the methods include ion exchange and chelation, and for solid minerals, preparation can be done through acid digestion, microwave, hydride generation, and alkaline digestion. Sample preparation for organic compounds can be further broken down depending on volatility, for semi-volatile organic compounds (SVOCs) and nonvolatile organic compounds (NVOCs) preparation for liquid samples can be done through liquid-liquid extraction, solid-phase microextraction, and solid-phase extraction. Solid samples under this category can be prepared by supercritical fluid extraction, ultrasonic extraction, soxtec, pressured fluid extraction and Soxhlet method (Chunlong,2007).
Sample Preparation for VOCs
Volatile organic compounds (VOCs) such the t-amyl alcohols can be done in two methods, purge and trap and also by static headspace extraction. The purge and trap technique involve purification of the sample by the use of helium or nitrogen and subjected to heat, the purge and trap chamber is used for compounds which are insoluble in water and have a boiling point of not more than 200oC and desorption occurs after rapid heating at the GC column. The second method is the static headspace extraction method involves establishing an equilibrium point to samples in a sealed vial.
The method utilizes a syringe of the large volume that will remove the static headspace gas from the given sample then passing it through a sorbent. The sorbent material takes up the gas and it’s later transferred into the GC for preparation. Given that not all volatile compounds can be purgeable, azeotropic and vacuum distillation can be put to place for the preparation of these compounds (Jeannot,2007).
Contamination and Safety
The high pollution effects of volatile organic compounds possess a dangerous threat to environmental pollution. When the contamination is detected especially in water its posses’ great threat to pregnant and nursing mothers, these compounds may include toluene that can cause abnormal development of the face and ears, Trichloroethylene (TCE) on the other hand causes cancer when in contact with animals and also humans.
Due to the health concerns of the risks associated with the volatile organic compounds, safety procedures are put in place when handling them and this includes the use of masks, gloves, and dust coats to the handlers. For disposal, it’s mandatory for industries and companies dealing with this compound to carry out decontamination before disposal and if not, they should be disposed of in a biohazard area that will not pose any effects to the environment (CDC,2004).