Guide for sampling and analysis of bisphenol A (BPA) in industrial effluent: chapter 6
6.0 Sampling Methods
- 6.1 Collection
- 6.2 Sampling Location
- 6.3 Manual Grab Sample
- 6.4 Composite Sample
- 6.5 Detailed Sampling Collection and Recovery Procedures
- 6.6 Sample Transportation and Delivery
The following sections provide information regarding sampling methods for BPA.
Upon arrival at the sampling site the individual collecting the samples should document the following activities and observations, referred to collectively as “field notes”:
- Time, date, location, names of sampling team members and other pertinent project information;
- Major tasks completed or carried out;
- Field temperature and pH of the collected samples;
- Significant observations with respect to the samples themselves (e.g., suspended solids) or the sample location (e.g., end-of-pipe or earlier in the process); and
- Sample identification numbers and their corresponding locations.
Once the sampling procedure as outlined in Section 4 has been determined, the individual collecting the samples can use the information provided in this section to ensure that the samples are collected properly.
During sample collection in the field, the sample collector must take care to ensure sample homogeneity, as results may vary if the sample is not adequately mixed during collection. The sample collector should take note of whether the collected samples visually contain suspended solids, as they may have an impact on the amount of BPA contained in the sample.
Although only one composite or grab sample of effluent is required per sampling event, equipment blanks are also recommended at the start of each event to ensure BPA from the equipment is not affecting the analytical results. To contribute to sample quality assurance/quality control (QA/QC), at least one set of duplicate samples should be taken annually.
It is recommended that there be an initial data collection period in order for all facilities to familiarize themselves with the monitoring process and to gather data on the concentrations of BPA being released to the environment. This would involve an increased sampling frequency during the first year of the program (up to monthly samples) and a subsequent reduction during the following years (minimum of quarterly), provided that the effluent concentration has not increased over this time period.
In the event that the BPA effluent concentration remains high or has increased during a time period (e.g., increase in production), it is recommended to increase the sampling for the duration of the time period. However, if the BPA effluent concentration has decreased (e.g., below the RMO 1.75 µg/L), the facility may consider reducing its sampling frequency as long as BPA releases remain constant.
6.2 Sampling Location
Effluent samples should be collected at the final discharge point. A final discharge point is an identifiable discharge point beyond which the industrial facility owner or operator no longer exercises control over the quality of the effluent. If sampling at this point is not possible, sampling can be taken earlier or later in the process, provided that effluent at the sampling location is as close as possible to the expected concentration of BPA resulting from normal operating conditions or could lead, by using an estimation method, to the concentration of BPA at the final discharge point.
As part of their monitoring plan, facilities should record sampling site information such as identifying the sampling location, the rationale for the site location, and the predicted concentration of BPA at the final discharge point as a result of any removal or treatment of BPA by the industrial facility.
6.3 Manual Grab Sample
A grab sample is the collection of a representative sample from a particular location using a short time period. A grab sample is normally taken at the surface of the water. In order to avoid surface films during the collection, the sample container should be inserted vertically into the water with the neck facing downwards. Once the sample container is submerged, it should be slowly inverted to allow water to flow in. If there is a current within the water body, the mouth of the container should face into it. If there is no current within the water body, the container should be slowly moved forward to obtain a continuous uncontaminated sample.
In some cases, a sample point may be very difficult to safely reach in order to obtain a grab sample (i.e., sampling from a manhole). The individual collecting the samples should use a stainless steel sample rod to extend his/her reach in order to safely obtain a sample. The rod may also allow the sample collector to directly use the BPAsample container to collect the sample. If the BPA sample container cannot be used, a glass or Teflon® jar should be used, and the sample collector can pour the effluent sample from the glass jar into the appropriate BPA sample container.
6.4 Composite Sample
Composite samples consist of two or more grab samples mixed together in known proportions. These samples may be collected manually or by an automatic sampler.
There are two main types of composite samples for effluent sampling:
- Time-weighted samples: grab samples of equal volume taken at constant intervals during the sampling period; and
- Flow-weighted samples: grab samples are proportional to the effluent flow rate or volume during the sampling period. Flow-weighted samples can be taken at constant intervals during the sampling period but with varying sample volumes that are proportional to the flow at the sampling time, or a fixed sample volume can be taken every time a fixed amount of effluent has passed the sampling point.
Time-weighted samples are typically used if the sample collector is aware that the effluent flow through the sample point will remain relatively constant over the duration of the sampling event. If a particular facility experiences significant variations in the flow rate of their final discharge point over the duration of the sampling event, it is preferable to collect samples using a flow-weighted basis. Flow-weighted sampling requires an accurate flow meter to provide guidance on when a grab sample must be collected.
When using composite samples, it is recommended that composite samples be collected at the facility’s final discharge point. This location is often in a manhole upstream of a municipal sewer connection; however, it may also consist of a discharge ditch or discharge pipeline. It is important to verify that the composite sampling event will incorporate all important plant activities so that representative effluent is collected (please refer to Section 5).
Automatic composite samples are prepared in much the same way as the manual composite samples. The main difference is that the sample collector must rely on an autosampler rather than collect the samples manually. It is recommended that sample collectors make use of an automatic sampler for any composite sampling events that are planned to occur over a period of 6 hours or longer, to ensure sampling consistency, accuracy and precision.
6.5 Detailed Sampling Collection and Recovery Procedures
Procedures for grab sampling, manual composite sampling and automatic sampling are described below.
6.5.1 Location Preparation
- a) If the final discharge point occurs in a manhole, remove manhole lid using a pickaxe and assess the water flow through the manhole:
- i. If there appears to be sufficient flow to keep the strainer completely submerged at all times, continue with sample collection procedures.
- ii. If there is insufficient flow to take samples, the flow path needs to be partially obstructed using a sandbag to create a pool of water from which the sample can be taken. The pool of water created by the sandbag will allow for sampling during low effluent flows.
Note: The sandbag must not be allowed to block the manhole. Blocking the manhole discharge can cause the sewer line to become backed up and may flood the facility. When installing the sandbag, lower it into the flow path using rope and tie it to the top rung of the manhole access ladder, keeping the rope taut so the sandbag does not have any slack to move if the flow increases. The sandbag should be installed such that the flow channel retains a small pool of water, approximately halfway down the flow channel to ensure that pooled water can still flow around the sandbag and through the manhole discharge.
- b) If the final discharge point occurs at the discharge from a pipeline, use a small stainless-steel bucket to provide a pool of sample water so that samples can easily be taken. The sample collector will need to use his/her judgment in the selection of the bucket size. For larger flow rates (>10 L/min), a larger bucket (20 L) will be required to reduce splashing; for smaller flow rates (< 10 L/min), a smaller bucket (5 L) will be required to ensure adequate turnover of the collected effluent in the bucket.
- c) If the final discharge point occurs at a discharge ditch, ensure that the flow through the ditch is sufficient to collect a sample at all times during the sampling event. Please refer to step a) ii) if the flow through the ditch appears too low to collect the samples.
6.5.2 Sample Collection Procedures
Manual grab sampling:
- Collect a similar volume of deionized water using the chosen, cleaned sampling equipment and pour it into a BPA sample container for the equipment blank (please refer to Section 7.2.1 for more information); and
- Take the sample using the sample container and the appropriate technique described in Section 6.3. It is important to ensure that the volumes of the grab samples can be accurately measured to ± 5%. Each sample must be of sufficient volume to fill the required 1-L sample containers.
Manual composite sampling:
- Collect a similar volume of deionized water using the chosen, cleaned sampling equipment and pour it into a BPA sample container for the equipment blank (please refer to Section 7.2.1 for more information);
- Take the sample using the sample container and the appropriate technique described in Section 6.4. It is important to ensure that the volumes of the samples are able to be accurately measured to ± 5%. Each sample must be of sufficient volume to result in enough composite samples at the end of the sampling event to fill the required 10-L sample jar;
- Pour each sample into a clean and decontaminated glass composite sample jar with ice packed around it to keep the sample cool. It is important for the sample collector to immediately refrigerate collected samples or put them in a cooler with cold packs or ice, to reduce degradation of the sample; and
- Continue collecting samples and adding them to the composite sampling jar every 20 minutes until the end of the sample event.
Automatic composite sampling:
- Measure the approximate length of tubing required so that the autosampler strainer is completely submerged in effluent;
- Attach a Teflon® and/or stainless steel strainer to one end of the suction tubing. Once the strainer is attached, ensure that it will not come off by tightening a gear clamp around the tubing/hose barb fitting on the strainer;
- Attach the tubing to the suction fitting on the autosampler pump. Once the tubing is attached, ensure that it will not come off by tightening a gear clamp around the tubing/hose barb fitting on the suction end of the autosampler pump;
- Submerge the strainer in deionized water and manually run the autosampler pump for 10 seconds to rinse the sample line, collecting the rinse water in the waste bucket;
- Collect an equipment blank using an appropriate volume of deionized water and the manual pumping option (please refer to Section 7.2.1 for more information);
- Using the autosampler interface, set up the sampling program. It is recommended that one sample be taken by the autosampler every 20 minutes for the duration of the sampling event. For example, the sampling program may be set up such that the autosampler would automatically collect at least 100 mL of effluent sample every 20 minutes for one 24-hour period (7.2 L of sample in total);
- Calibrate the sample volume using deionized water and a graduated cylinder. Typically, this is done during the sampling program set-up and may involve inputting the length of tubing used or setting the pumping interval required to obtain the desired sample volume. It is important to ensure that the volumes of the samples are able to be accurately measured to ± 5%. Each sample must be of sufficient volume to result in enough composite samples at the end of the sampling event to fill the 10-L sample jar;
- Place a clean and decontaminated glass or stainless-steel composite sample jar inside the autosampler and ensure that the discharge tubing from the pump is positioned such that the sample will enter the container;
- Pack ice around the outside of the sample container to keep it in place and to reduce degradation of the sample. It is important for the sample collector to refrigerate collected samples immediately or put them in a cooler with cold packs or ice to prevent degradation of the sample;
- Take care not to kink the sampler tubing and ensure that the strainer is fully submerged in effluent when the autosampler is put into operation. Manhole installation brackets should be used if installing an autosampler in a manhole for the sampling event; and
- Verify that the autosampler is functioning and that the sample is being collected by observing the first sample collection performed by the autosampler.
6.5.3 Sample Recovery Procedure
Once sampling is complete, the following procedure should be followed to recover any type of sample:
- Wearing nitrile gloves, take the temperature and pH (pH can also be measured by the laboratory) of the sample and note it in the field notes. Make note if the ice in the autosampler has melted;
- Thoroughly mix the grab sample or composite sample to ensure that any particulate is re suspended into the sample before collecting the samples;
- To take samples, pour the effluent from the sample collection container directly into the sampling jar to avoid any contamination from intermediate equipment. Repeat this process until all of the BPA samples have been transferred to the sampling jar;
- If required, due to the nature of the effluent (e.g., effluent has high bacterial concentration), add a preservative agent to the sampling jar (e.g., 10 mL per 1 L of 37% formalin). Please contact the laboratory to ensure the preservative is compatible with the analytical test method;
- Immediately place filled sample jars in the cooler with ice/cold packs to minimize BPA degradation during transit;
- Dispose of the remaining sample (if any is left) in the wastewater; and
- Replace the manhole lid (if required) and clean up all equipment.
6.6 Sample Transportation and Delivery
After BPA samples are collected, it is important that they be delivered to the analytical laboratory as quickly as possible so that they can be properly stored in a refrigerator at the required holding temperature. The cooler with ice/cold packs should only be used as temporary storage during transportation to the laboratory. The recommended holding time is 28 days refrigerated between 0 and 4°C.Footnote 2
It is important for the individual collecting the samples to specify the low BPAconcentration analysis method for any equipment blanks rather than the regular BPA analysis method for effluent samples.
Prior to relinquishing custody of the BPA samples to the analytical laboratory, it is imperative that the Chain of Custody (COC) forms be completely filled out by the individual who performed the sampling and transported the samples to the lab. As discussed further in Section 9.4, COC forms demonstrate the integrity of the samples and instill confidence in the sample results. If responsibility for the samples needs to be transferred at any time, this information should also be captured on the COC.
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