Automating and Simplifying the Forensic Sample Workflow

with Maxprep® Liquid Handler

Anupama Gopalakrishnan, Promega Corporation

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Introduction

In forensic laboratories, the process of obtaining high-quality genetic identity information from complex forensic samples demands precision, consistency, and efficiency. Advances in technology have introduced a range of automated methods that streamline workflows, minimize human error, and accelerate sample processing. The Maxprep® Liquid Handler is one such innovation, offering integrated solutions for forensic workflows from sample preprocessing to post-extraction analysis. By leveraging automation and Portal Software from Promega, forensic laboratories can integrate, track, and analyze genetic information seamlessly. This article explores the various methods available for forensic workflows, their integration through Portal, and the numerous advantages offered by automation.

Streamlining Forensic DNA Workflows with Automation

A forensic workflow typically begins with sample collection and preprocessing, followed by DNA extraction, quantification, normalization, amplification, and analysis. Each step requires careful handling to maintain sample integrity and ensure consistent, reproducible results. Promega’s Maxprep® Liquid Handler and Maxwell® Instruments offer a suite of preprogrammed methods for genetic identity workflows that automate these processes.

1. Sample Preprocessing for Maxwell® Extraction

Before DNA extraction, forensic samples such as swabs, blood stains, or tissue must be properly digested and prepared. The Maxprep® Liquid Handler can process 1–48 samples integrating with (2) 24-position Maxwell® RSC 48 or (2) 16-position Maxwell® RSC removable trays for DNA extraction.

The Maxprep® Liquid Handler automates critical preprocessing steps, reducing hands-on time and ensuring uniform handling of samples. Two key preprocessing methods are:

  • Maxwell® FSC DNA IQ™ Casework Method (from Tubes): Following manual preprocessing of samples on solid substrate, this method automates the addition of lysis buffers, sample transfers to Maxwell® cartridges, addition of elution buffer to elution tubes, and plunger placement into cartridges for DNA extraction. (TM499 Manual)
  • MaxSpin® 96 Casework Pre-processing Method: The MaxSpin® 96 Casework Extraction method extracts casework solid-support samples in the MaxSpin® 96 by adding lysis reagents into the spin-baskets in the MaxSpin® 96 plate. Heated incubation may also be performed on the Maxprep® Liquid Handler. The Maxwell® FSC DNA IQ™– MaxSpin® 96 method then prepares Maxwell® deck trays for the Maxwell® FSC DNA IQ™ Kit using extracted samples in the MaxSpin® 96 plate. (TM670 Manual)

These automated preprocessing methods ensure that samples are consistently prepared for DNA extraction, reducing variability and optimizing recovery.

2. DNA Quantification and Standard Curve Preparation

Accurate quantification is essential for determining human DNA concentration in forensic samples. Quantification helps identify the appropriate DNA input for downstream processes such as short tandem repeat (STR) analysis. The PowerQuant® System enables laboratories to assess DNA quantity, quality, and degradation in forensic samples efficiently.

  • PowerQuant® System Setup: The Maxprep® Liquid Handler automates the preparation of qPCR quantification reactions, including: - Preparation of the master mix. - Serial dilution of DNA standards to generate a standard curve. - Transfer of standards, controls, and samples into amplification plates (TM651 Manual).

3. DNA Normalization and STR Amplification Setup

Once DNA is quantified, it must be normalized to ensure that input DNA amounts are consistent for STR amplification. Manual normalization can be error-prone and time-consuming, but automated methods overcome these challenges:

  • DNA Normalization and STR Setup: The Maxprep® Liquid Handler performs DNA normalization and prepares amplification reactions for STR analysis. This method includes: - Normalization of sample concentrations to a user-specified target DNA mass. - Preparation of STR master mix using components such as primer pair mix, STR master mix, and 5X AmpSolution™ Reagent. - Transfer of normalized samples, controls, and master mix to amplification plates (TM576 Manual).

By automating normalization and STR setup, laboratories can ensure uniform or optimal input across all samples, improving downstream amplification results.

4. Direct Amplification STR Methods

Forensic workflows often require rapid and direct amplification of samples without prior DNA extraction. The Maxprep® Liquid Handler supports direct amplification of STRs from swabs or punches:

  • Direct Amp STR Setup of Punches: This method prepares STR reactions directly from punches of storage cards (e.g., FTA cards), eliminating the need for DNA extraction. The Maxprep® Liquid Handler prepares reaction mixes, adds controls, and dispenses the mix into amplification plates containing punches (TM585 Manual).
  • Direct Amp STR Setup of Swabs: Samples prepared in SwabSolution™ are directly amplified for STR analysis. The Maxprep® Liquid Handler automates master mix preparation, control placement, and sample setup (TM607 Manual).

Direct amplification methods save time and minimize the risk of DNA loss during extraction.

5. Capillary Electrophoresis (CE) Sample Setup

Following STR amplification, capillary electrophoresis (CE) is used to separate and analyze STR fragments for DNA profiling. Manual CE setup can be laborious, but the Maxprep® Liquid Handler simplifies this process:

  • CE Sample Setup: The Maxprep® Liquid Handler prepares CE injection plates by: - Creating loading cocktails containing Hi-Di™ formamide and internal lane standards (ILS). - Transferring samples, controls, and allelic ladders into CE injection plates (TM650 Manual).

This method can prepare up to two CE injection plates simultaneously, streamlining the transition to fragment analysis.

Integration Through Promega Portal

Forensic laboratories handle large volumes of data that must be tracked throughout the entire workflow. Promega’s Portal Software serves as a central hub for data integration, ensuring seamless communication between instruments, methods, and sample tracking systems.

1. Sample Tracking

The Portal Software allows laboratories to import sample IDs, plate maps and barcodes directly into the Maxprep® Liquid Handler and Maxwell® Instruments. As samples move through the workflow, the Portal automatically tracks:

  • Sample IDs.
  • Sample locations in labware (e.g., Maxwell® deck trays or CE plates).
  • Processing details such as quantification results, normalization parameters, and amplification setups.

By eliminating manual data entry, Portal reduces transcription errors and ensures that every sample is accounted for.

Figure 1: Infographic depicting the role of Portal Software in a forensic workflow with Maxprep® and Maxwell® instruments. The Portal Software serves as a hub for sample ID, plate maps and quantitation information, while the Maxprep® assists in Maxwell® set up for DNA purification and setting up quantitation assays for a qPCR instrument. Quantitation data, now associated with Sample ID, can now be used by the Maxprep® to perform normalization for STR amplification. Finally, Maxprep® can help with CE setup for fragment analysis. The Portal Software maintains the sample information integrity throughout the workflow.

2. Workflow Automation

Portal integration allows laboratories to use predefined methods, assays, and workflows effectively. For example:

  • Sample identifiers and quantitation data can be imported into the Portal as a structured tab-delimited text file.
  • Quantification data generated during qPCR runs is fed back into the Portal for use in downstream normalization methods by the Maxprep® Liquid Handler.
  • Consumables can be managed effectively as the Portal software can provide run-specific consumable guidance and track consumable usage.

3. Data Reporting

The Portal Software generates comprehensive reports for each step of the forensic workflow. These reports include:

  • Sample tracking details.
  • Quantification results.
  • Normalization parameters.
  • Method-specific data (e.g., standard curve details, STR setup information).

By centralizing all data, Portal simplifies documentation, facilitates quality assurance, and ensures compliance with forensic laboratory standards.

Advantages of Automation in Forensic Workflows

Automated instruments like the Maxprep® Liquid Handler and Maxwell® Systems provide forensic labs with:

  • Consistency and Accuracy: Automation ensures error-free, reproducible workflows critical for reliable DNA profiling.
  • Efficiency and Throughput: Speeds up tasks like reagent preparation and CE setup, enabling faster sample processing and higher throughput.
  • Sample Integrity: Reduces handling to minimize contamination or DNA loss, critical for limited samples.
  • Data Integration: Maxprep® and Portal Software streamline data tracking and sharing, reducing manual errors.
  • Ease of Use: Preprogrammed methods and intuitive interfaces simplify training and operation.
  • Compliance: Automated documentation ensures adherence to forensic standards and regulatory requirements.

To schedule a virtual demo or a consultation with Promega’s automation experts, email to genetic@promega.com or

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