LC-MS/MS Scientist

LC-MS/MS Scientist (Clinical Assay Development) 📍 Austin, TX | 🧪 On-site | 🕓 Full-time About EndlessDx Laboratory At EndlessDx, we’re building a modern clinical laboratory that pairs analytical rigor with real-world impact. We’re CLIA/CAP-accredited, and our LC-MS/MS assays directly power preventive and precision medicine programs. We’re a small startup team that moves fast and changes course when the data tells us to. We value deep technical mastery, clean data and practical science, and we care about turning good ideas into working products quickly. If you want your work to reach real patients instead of sitting in a thesis binder, this is the place.

About the Role
We’re hiring an LC-MS/MS Scientist to own clinical assays from first idea to live production. You’ll work closely with our scientists, ops and product teams every day, take the lead on methods that go live, and help shape how our mass spec lab grows. Priorities here shift as we learn, so you’ll need to adapt quickly and keep things moving. What You’ll Do
• Turn new assay ideas into validated, production-ready LC-MS/MS methods (triple quadrupole) under CLIA/CAP requirements, fast
• Develop, optimize and validate quantitative methods, iterating quickly from proof-of-concept to clinical use
• Design and run sample prep workflows (protein precipitation, LLE, SPE, derivatization) for serum/plasma and DBS/card matrices
• Operate, maintain and troubleshoot SCIEX 7500+ and UHPLC systems
• Find and fix real-world issues like matrix effects, ion suppression, interferences and carryover
• Write and execute validation plans, SOPs and study reports
• Work in a production LIMS environment and uphold regulated lab workflows and data integrity practices
• Work hands-on with lab, ops and product teammates to get new tests launched and improve the ones already running
• Help improve throughput, robustness and quality as our test menu and volume grow What We’re Looking For
• MS or PhD in Analytical Chemistry, Biochemistry, Pharmaceutical Sciences or a related field, or a BS with equivalent hands-on industry experience
• Hands-on experience developing or running quantitative LC-MS/MS methods (academic or industry)
• Strong grasp of quantitative mass spectrometry and applied analytical science
• A fast learner who picks up new instruments, matrices and techniques quickly and goes looking for what they don’t know yet
• Adapts quickly when priorities, timelines or data change, without losing rigor
• Builder mindset: you like turning an idea into a working assay or product fast, then improving it
• Loves a highly interactive, fast-changing startup environment: you’d rather be in the room working through a problem than waiting on a ticket
• Detail-oriented and comfortable owning assays that directly affect patient care Big Plus (Not Required)
• Experience with:
• Triple quadrupole quantitation
• Stable isotope internal standards
• Hormones, steroids, PFAS or biomarkers
• DBS workflows
• Experience in a clinical lab, diagnostics or regulated bioanalysis (CLIA/CAP, GLP or similar)
• Method validation experience to CLSI or FDA bioanalytical guidelines
• Startup or early-stage company experience Why This Role Matters Our LC-MS/MS lab is the core engine of EndlessDx. You won’t be a cog, and you won’t wait months to see your work used. The methods you build may be running on patient samples within weeks. You’ll get to:
• Take ideas from concept to clinical product quickly
• Learn fast across assay development, regulated lab ops and product
• Shape how a regulated, growing lab operates
• Work in a small, highly collaborative team where your input changes what we build Competitive salary plus equity.

How to Apply
Apply via LinkedIn or email your CV with a short note (Why EndlessDx? What’s something you learned fast or built fast?) to: 📧 wenli@endless.health If you get excited about calibration curves, matrix effects, why one transition is misbehaving, and how quickly you can fix it, we should talk.