By Albert Robbat, Jr., PhD

Introduction
Part 1: Challenges Faced by the Typical Environmental Lab
Part 2: Making Process Improvements & Reducing Costs
Part 3: Recommendations

Introduction

The environmental segment of the independent testing industry produces more than $1 billion in sales annually and is a highly commoditized market. An environmental laboratory's fundamental dilemma is how best to compete in a market where most labs follow the same prescribed methods, use the same analytical instrumentation, and employ little innovative technologies to differentiate themselves in the marketplace.

Growth and profits for the industry have been based solely on an acquisition strategy and improving operational efficiencies in the supply chain within and among different facilities. This strategy cannot be maintained in a commoditized market over the long term. Although survivors gain scale and market scope through contraction, profitability, which currently averages about 7% across the industry, will suffer.

Part 1: Challenges Faced by the Typical Environmental Lab

An operational management study was recently conducted through interviews and lab tours with senior executives and lab managers from several representative commercial environmental labs in the Northeast US. Based on the information obtained, a typical laboratory was created that is an amalgamation of these entities.

This white paper evaluates a typical lab's sample preparation procedures and analysis methods for the detection of EPA method 8270 target compounds as well as organochlorine biphenyls and pesticides. We assess process flow as a function of lab capacity, as shown in Table 1; see Figures 1 and 2 for typical lab process flow and operating procedures.

Table 1 - Assumptions include the lab operation and analysis method cycle times as well as the time per task for sample log in, instrument, customer, and QC sample setup and performance checks, sample preparation, analysis and data review times. (Click thumbnail for full-sized image.)

Sample Flow
On average, the typical lab processes over 13,000 projects or about 65,000 samples a year. Turnaround time is approximately five business days. They support all environmental and industry applications - from solid and hazardous waste to wastewater and water supply. The goal is to provide an accurate, high quality product on time and at a reasonable cost.

Figure 1 shows sample flow through the typical lab, from delivery of samples to final mailing of reports to customers.

Figure 1 - Flow of samples through the laboratory. (Click thumbnail for full-sized image.)

Sample Preparation Process
Soil or water sample preparation for EPA method 8270 GC/MS analysis is a three step process: (1) extraction of the target compounds from the sample with solvent, (2) solid phase extraction to remove chemical interferences, and (3) concentration of the sample for analysis.

The Analysis Bottleneck
Sample extracts are injected into a gas chromatography/mass spectrometry (GC/MS) instrument. GC/MS provides unambiguous compound identification and is the most often used instrument for the quantitative analysis of organic compounds.

The typical lab operates 23 hours per day on average and processes 150 customer samples, or about 15 samples from 10 customers. The total number of samples analyzed per day, however, is much more. The total number includes the 150 customer samples as well as QC samples and reanalyzed customer and QC samples due to a failure to meet regulatory agency standards or a failure to identify targets in the presence of an interfering matrix.

The GC/MS EPA method 8270 analysis run-time is 32 minutes per sample, with an instrument cycle time of 34 minutes per sample (including cool down). If four GC/MS instruments are available, the maximum sample capacity of the typical lab is 145 samples per day. If instrument and QC samples are subtracted, the total number of actual customer samples is 106 per day.

The typical lab may analyze 20% of its customer samples by GC/ECD. It may have a QC and/or customer reanalysis rate of 25% and 15%, respectively. This results in a daily backlog of 32 samples per day or 160 samples over a 5-day work week. To eliminate this backlog the lab cannot accept any additional samples and must operate over the weekend to catch up. One way of increasing capacity is to reduce the reanalysis rate. Unfortunately, this is easier said than done.

The High Cost of Reanalysis
Reanalysis samples occur when customer and QC data fail to meet performance standards. For example, sample extracts must be reanalyzed if customer or QC "spiked" samples or laboratory control-check samples fail QC (first pass in Figure 1). If the reanalyzed extract fails QC for the second time, the entire sample must be re-extracted and reanalyzed at no additional cost to the customer (second pass). Often, highly complex customer samples are reanalyzed multiple times before target and standard compounds are identified and pass QC, or when low concentration analytes are quantified in the presence of high concentration interferents or target compounds.

QC Samples & Frequency of Failures
Although the EPA only requires that four of the 24 batch-samples must be QC samples, a typical lab can analyze the same number of QC and customer samples. We found the QC reanalysis rate to be 3.5 times higher than customer samples, which is an easier performance measure to track.

Figure 2 - Instrument workstations (Click thumbnail for full-sized image.)

Figure 2 shows the initial calibration and daily analysis procedures for semivolatile organic compounds (SVOC) samples. Initial instrument calibration is made when new instruments are brought online, instrument maintenance is needed, or after cross-contamination of samples is detected and when the instrument fails to meet continuing and sample QC performance standards.

Frequency of failures greatly influences sample backlog logistics, productivity, and, thus, cost. We found it takes a typical lab two hours to prepare standards, 21 hours to run standards, two hours to analyze GC/MS data and make calibration plots. This amounts to a two to three day process before customer samples can be analyzed.

The time to run the continuing calibration standard and QC samples are included in the daily utilization rate, since these are analyzed every 12 hours along with customer samples. It is striking to note the number of samples a typical lab reanalyzes to meet performance standards.

Why Such Long GC/MS Run-Times?
The purpose of the GC is to separate the 8270 method compounds in the target compound list and introduce them one-by-one into the MS. The MS then provides unambiguous compound identification. Hence, the long run-times.

If the sample is contaminated with petroleum by-products (e.g. oil contains 150 compounds and gasoline 250), for any one target compound there is the potential of more than 400 interfering compounds. In addition, extract cleanup is carried out to remove as many of the interfering compounds as possible, without losing the target compounds or QC standards. Figure 2 lists the procedure a typical lab follows to prepare the instrument and analyze samples.

Albert Robbat, Jr., is Founder and Chairman of Ion Signature Technology.

Go to Part 2: Making Process Improvements & Reducing Costs