The Seven Steps of Laboratory Process

Each step signifies a milestone in the sample s travel through the laboratory. Unlike other seven-step diagrams with irreversible flow that we have seen in previous chapters, a unique feature of laboratory process is that the relationships between individual steps are for the most part reversible. This means that there is a viable chance to correct an error made at the previous step. This reversibility is the greatest advantage of the laboratory process. As laboratories handle thousands of samples and analyze them by dozens of various methods, the possibility for making an error at any step is real, but so is the opportunity to correct the error. Obviously, some errors 

There are several critical areas in the laboratory process, which have a potential to completely invalidate a sample in a technical sense and from a legal perspective. Because the laboratory process is poorly understood by most of the outsiders, we will review every step of it in order to comprehend the relationships between different steps and to recognize the effects each one has on data quality. 

Samples are received at the laboratory by a group of people designated as Sample Custodians who work within the Sample Receiving Section. This section is typically responsible for entering the COC Form information into the LIMS sample storage the preparation of sample containers and coolers on client s request and the disposal of expired samples. These procedures must be documented in laboratory SOPs that are kept readily available at the sample receiving area. 

Sample Custodians open the coolers, remove the COC Forms and verify the COC Form against the cooler contents. At many laboratories, Sample Custodians will not sign and date the COC Form and log-in a sample into the LIMS until all identified discrepancies have been resolved with the client. The resolution of outstanding issues may delay the start of analysis and erode the sample holding time. The following mistakes made by field sampling personnel are detected at this first step of the laboratory process  

Sample Custodians determine from the COC Form whether a temperature blank has been enclosed with the samples. If a temperature blank has been enclosed, Sample Custodians remove the ice, the packing material, and the samples from the cooler and line them up on a receiving table or in a fume hood, if samples emanate odor. They measure the cooler temperature by inserting a thermometer into the temperature blank. If the blank is not present, they measure the temperature inside the cooler by placing a thermometer or an infrared temperature probe between sample containers. The temperature of the cooler upon arrival to the laboratory should be 2-6°C whether it has been measured inside the cooler or in the temperature blank. To document sample conditions upon arrival at the laboratory, laboratories record the cooler temperature on the COC Form or use a separate cooler receipt form, similar to one shown in Appendix 17. Samples are then placed in storage refrigerators or walk-in coolers kept at 2-6°C. 

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