Clause 7.7 7.7.1

You asked

"The resulting data shall be recorded in such a way that trends are detectable and, where practicable, statistical techniques shall be applied to review the results. This monitoring shall be planned and reviewed and shall include, where appropriate, but not be limited to from (a to K) please can you explain b, c, d, h

Option b involves an equivalence study, were you would compare for the same method;  the performance of new instrument or technology to previously validated one. An example would be changing the analysis part of a test method from Atomic absorption spectroscopy (AAS) to ICP-OES (Inductively coupled plasma - optical emission spectrometry).

Option c, being functional checking involves evaluating the performance of the equipment. Depending on the equipment, this may be provided via software, for example checking analytical sensitivity before starting analysis.

Option d simply involves running samples or standards that are not certified reference materials, but laboratory in house samples or standards. For example you prepare a sample in bulk, well homogenised and stable that you use for you validation, determine mean and standard deviation; establish a control chart with limits and then run the sample routinely comparing the result against previous results.

Option h involves using professional knowledge of characteristics that have a known correlation. As a simple example there is, by principle of pH measurement;  a positive correlation between soil pH and extractable Ca and Mg.

You also asked to explain

Data from monitoring activities shall be analysed, used to control and, if applicable, improve the laboratory’s activities. If the results of the analysis of data from monitoring activities are found to be outside pre-defined criteria, appropriate action shall be taken to prevent incorrect results from being reported."

The pre-defined criteria can include for example, allowed variance between replicates (acceptable %), that the control sample must fall within an acceptable limited range of results (between upper and lower limit); and over time, a random up and down pattern around the mean is observed for plotted results. The laboratory must state the criteria based on risk and purpose of the test.  When you monitor a test result using regular control charts, you firstly establish your mean and standard deviation using typically, at least 30 results over a period of time. You then establish the limits 2 or 3 standard deviations from the mean, depending on the level of confidence you require.  This means that that at 2 SD there is 95% confidence that the sample results should fall in the range. Note this also means at 95 % Confidence 5 out of 100 may will fall outside, but may not be statistically significant. You must consider the signifance. Simply what a laboratory is looking for is acceptable variation (deviation), realistic limits and if a deviation is observed, stop and consider the impact before releasing results. If trends are observed within the limits, for example consecutive points indicating a positive bias above the mean, consider the risks and opportunity to investigate and make improvements.

The following ISO 17025 document template may assist further:
Quality Assurance Procedure at hhttps://advisera.com/17025academy/documentation/quality-assurance-procedure/