diff --git a/CHANGELOG.md b/CHANGELOG.md
index 26e73741..9402f032 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,17 @@ All notable changes to this project are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/),
 and this project adheres to [Semantic Versioning](https://semver.org/).
 
+## [1.8.1] - 2026-08-25
+
+### Fixed
+- LC/MS layout detection: a plain MS jcamp is no longer rendered with the LC/MS layout (#322)
+
+### Dependencies
+- Bump shell-quote 1.8.4 → 1.10.0 (#319)
+- Bump fast-uri 3.1.2 → 3.1.5 (#320)
+
+[1.8.1]: https://github.com/ComPlat/react-spectra-editor/releases/tag/v1.8.1
+
 ## [1.8.0] - 2026-06-29
 
 ### Added
diff --git a/dist/features/lc-ms/parsing/chemstation.js b/dist/features/lc-ms/parsing/chemstation.js
index d5f328c0..961c257f 100644
--- a/dist/features/lc-ms/parsing/chemstation.js
+++ b/dist/features/lc-ms/parsing/chemstation.js
@@ -5,6 +5,7 @@ Object.defineProperty(exports, "__esModule", {
 });
 exports.parseChemstationPages = exports.isChemstationLcms = void 0;
 var _lcmsMsPage = require("./lcmsMsPage");
+var _lcmsCategory = require("./lcmsCategory");
 const parseChemstationPages = (source, jcamp) => {
   if (typeof source !== 'string') return [];
   const parts = source.split(/##PAGE=/);
@@ -58,51 +59,58 @@ const parseChemstationPages = (source, jcamp) => {
   }
   return spectra;
 };
+
+// `\bTIC\b` rather than includes('TIC'), so STATIC / KINETIC / SYNTHETIC / OPTIC
+// do not read as a total-ion chromatogram.
 exports.parseChemstationPages = parseChemstationPages;
+const TIC_TOKEN = /\bTIC\b/;
+
+// A JCAMP label repeated across blocks arrives from jcampconverter as an array
+// rather than a string, so every record read here is normalised to a list.
+const upperList = value => [].concat(value == null ? [] : value).map(entry => String(entry).toUpperCase());
+const upperTokens = value => upperList(value).reduce((acc, entry) => acc.concat(entry.split(/[,;]/)), []).map(token => token.trim()).filter(Boolean);
 const isChemstationLcms = (source, jcamp) => {
   if (typeof source !== 'string') return false;
-  const dt = String(jcamp?.dataType || jcamp?.info?.DATATYPE || '').toUpperCase();
-  if (dt.includes('LC/MS') || dt.includes('MASS TIC')) return true;
-  const spectra = Array.isArray(jcamp?.spectra) ? jcamp.spectra : [];
   const info = jcamp?.info || {};
-  const scanMode = String(info.SCAN_MODE || info.SCANMODE || '').toUpperCase();
+  const spectra = Array.isArray(jcamp?.spectra) ? jcamp.spectra : [];
+  // jcampconverter leaves the root `dataType` undefined and canonicalises
+  // `##DATA TYPE` to info.DATATYPE, which may be an array on repeat.
+  const dataTypes = upperList(jcamp?.dataType ?? info.DATATYPE);
+  const spectrumDataTypes = spectra.map(s => String(s?.dataType || '').toUpperCase());
   const type = String(info.TYPE || '').toUpperCase();
+
+  // 1. The file declares itself an LC/MS run or a total-ion chromatogram.
+  if (dataTypes.some(d => d.includes('LC/MS') || d.includes('MASS TIC'))) return true;
+
+  // 2. A block declares chromatogram content.
+  if (spectrumDataTypes.some(d => TIC_TOKEN.test(d))) return true;
+  if (type.includes('MS CHROMATOGRAM')) return true;
+  const hasMassSpectrumRootDataType = dataTypes.some(d => d.includes('MASS SPECTRUM'));
+  const scanMode = (0, _lcmsCategory.normalizeLcMsMode)(info.SCAN_MODE ?? info.SCANMODE);
   const software = String(info.SOFTWARE || '').toUpperCase();
-  const csCategory = jcamp?.info?.$CSCATEGORY;
-  const categories = Array.isArray(csCategory) ? csCategory.map(c => String(c).toUpperCase()) : [];
-  const hasPolarityCategory = categories.some(c => c.includes('POSITIVE') || c.includes('NEGATIVE') || c.includes('NEUTRAL'));
-  const hasTicOrUvvisCategory = categories.some(c => c.includes('TIC') || c.includes('UVVIS'));
-  const hasHplcUvvisSpectrumDataType = spectra.some(s => {
-    const sdt = String(s?.dataType || '').toUpperCase();
-    return sdt.includes('HPLC UV-VIS') || sdt.includes('UVVIS');
-  });
-  const hasMassTicSpectrumDataType = spectra.some(s => {
-    const sdt = String(s?.dataType || '').toUpperCase();
-    return sdt.includes('MASS TIC') || sdt.includes('TIC');
-  });
-  const hasMassSpectrumDataType = spectra.some(s => {
-    const sdt = String(s?.dataType || '').toUpperCase();
-    return sdt.includes('MASS SPECTRUM');
-  });
-  const hasMassSpectrumRootDataType = dt.includes('MASS SPECTRUM');
-  const hasScanModeHint = scanMode.includes('POSITIVE') || scanMode.includes('NEGATIVE') || scanMode.includes('POSITIV') || scanMode.includes('NEGATIV');
-  const hasTypeHint = type.includes('MS SPECTRUM') || type.includes('MS CHROMATOGRAM');
-  const hasSoftwareHint = software.includes('OPENLAB');
-  const hasMultipleSpectra = spectra.length > 1;
-  const hasPageMetadata = spectra.some(s => s?.page != null || s?.pageValue != null);
-  const hasNtuplesPageHeader = /##NTUPLES_PAGE_HEADER\s*=/.test(source);
-  if (hasNtuplesPageHeader && (hasTicOrUvvisCategory || hasHplcUvvisSpectrumDataType || hasMassTicSpectrumDataType || hasMassSpectrumDataType && hasPolarityCategory)) {
-    return true;
-  }
-  if (hasMultipleSpectra && hasPageMetadata && (hasTicOrUvvisCategory || hasHplcUvvisSpectrumDataType || hasMassTicSpectrumDataType || hasMassSpectrumDataType && hasPolarityCategory)) {
-    return true;
-  }
-  if (hasMassSpectrumRootDataType && (hasMassSpectrumDataType || hasScanModeHint || hasTypeHint || hasSoftwareHint)) {
-    return true;
-  }
-  if (hasMassTicSpectrumDataType && (hasTypeHint || hasSoftwareHint || hasScanModeHint || spectra.length > 0)) {
-    return true;
+
+  // 3. Structural discriminator. A Chemstation LC/MS export indexes its m/z scans
+  //    by a retention-time PAGE variable (`##VAR_TYPE= PAGE, X, Y`); that page axis
+  //    is what makes the file chromatographic. A plain chem-spectra MS NTUPLES
+  //    export declares its time axis as a third INDEPENDENT variable
+  //    (`##VAR_TYPE= INDEPENDENT, DEPENDENT, INDEPENDENT`, `##SYMBOL= X, Y, T`) and
+  //    never declares a PAGE. Deciding on structure rather than on a units literal
+  //    means writer-to-writer differences in spacing or vocabulary cannot flip it.
+  //    Note `##VAR_TYPE` reaches us as info.VARTYPE - canonicDataLabels strips the
+  //    underscore and uppercases - and `##NTUPLES` is not retained at all.
+  const hasPageAxis = upperTokens(info.VARTYPE).includes('PAGE') || /##NTUPLES_PAGE_HEADER\s*=/.test(source);
+  if (hasPageAxis) {
+    // A PAGE axis alone is not conclusive - 2D NMR is page-indexed too - so the
+    // page-indexed content still has to look like LC/MS.
+    const categories = upperList(info.$CSCATEGORY);
+    return hasMassSpectrumRootDataType || spectrumDataTypes.some(d => d.includes('MASS SPECTRUM')) || spectrumDataTypes.some(d => d.includes('HPLC UV-VIS') || d.includes('UVVIS')) || categories.some(c => TIC_TOKEN.test(c) || c.includes('UVVIS')) || categories.some(c => c.includes('POSITIVE') || c.includes('NEGATIVE') || c.includes('NEUTRAL')) || scanMode !== 'NEUTRAL' || software.includes('OPENLAB');
   }
-  return false;
+
+  // 4. No page axis: fall back to vendor identity for the Chemstation exports that
+  //    predate the page-indexed layout. Deliberately excludes a MASS SPECTRUM
+  //    per-block dataType and `##TYPE= MS SPECTRUM` - a plain MS export carries
+  //    both, and treating them as chromatographic evidence is what made a plain
+  //    file render as LC/MS in the first place.
+  return hasMassSpectrumRootDataType && (software.includes('OPENLAB') || scanMode !== 'NEUTRAL');
 };
 exports.isChemstationLcms = isChemstationLcms;
\ No newline at end of file
diff --git a/dist/helpers/chem.js b/dist/helpers/chem.js
index c22b0c25..aec2fa66 100644
--- a/dist/helpers/chem.js
+++ b/dist/helpers/chem.js
@@ -1139,7 +1139,7 @@ const ensureSpectrumData = (spectrum, source) => {
 const ExtractJcamp = source => {
   const jcamp = _jcampconverter.default.convert(source, {
     xy: true,
-    keepRecordsRegExp: /(\$CSTHRESHOLD|\$CSSCANAUTOTARGET|\$CSSCANEDITTARGET|\$CSSCANCOUNT|\$CSSOLVENTNAME|\$CSSOLVENTVALUE|\$CSSOLVENTX|\$CSCATEGORY|\$CSITAREA|\$CSITFACTOR|\$OBSERVEDINTEGRALS|\$OBSERVEDINTEGRALSGROUPS|\$OBSERVEDMULTIPLETS|\$OBSERVEDMULTIPLETSPEAKS|\.SOLVENTNAME|\.OBSERVEFREQUENCY|\$CSSIMULATIONPEAKS|\$CSUPPERTHRESHOLD|\$CSLOWERTHRESHOLD|\$CSCYCLICVOLTAMMETRYDATA|UNITS|SYMBOL|\$CSAUTOMETADATA|\$DETECTOR|MN|MW|D|MP|MELTINGPOINT|TG|\$CSSCANRATE|\$CSSPECTRUMDIRECTION|\$CSWEAREAVALUE|\$CSWEAREAUNIT|\$CSCURRENTMODE|\$CSLCMSMZPAGE|SCAN_MODE|SCANMODE|TYPE|SOFTWARE|DATATYPE)/ // eslint-disable-line
+    keepRecordsRegExp: /(\$CSTHRESHOLD|\$CSSCANAUTOTARGET|\$CSSCANEDITTARGET|\$CSSCANCOUNT|\$CSSOLVENTNAME|\$CSSOLVENTVALUE|\$CSSOLVENTX|\$CSCATEGORY|\$CSITAREA|\$CSITFACTOR|\$OBSERVEDINTEGRALS|\$OBSERVEDINTEGRALSGROUPS|\$OBSERVEDMULTIPLETS|\$OBSERVEDMULTIPLETSPEAKS|\.SOLVENTNAME|\.OBSERVEFREQUENCY|\$CSSIMULATIONPEAKS|\$CSUPPERTHRESHOLD|\$CSLOWERTHRESHOLD|\$CSCYCLICVOLTAMMETRYDATA|UNITS|SYMBOL|\$CSAUTOMETADATA|\$DETECTOR|MN|MW|D|MP|MELTINGPOINT|TG|\$CSSCANRATE|\$CSSPECTRUMDIRECTION|\$CSWEAREAVALUE|\$CSWEAREAUNIT|\$CSCURRENTMODE|\$CSLCMSMZPAGE|SCAN_MODE|SCANMODE|VAR_TYPE|VARTYPE|TYPE|SOFTWARE|DATATYPE)/ // eslint-disable-line
   });
   const isChemstation = (0, _parsing.isChemstationLcms)(source, jcamp);
   const parsedPages = (0, _parsing.parseChemstationPages)(source, jcamp);
diff --git a/package.json b/package.json
index 60032d86..b730b3b9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@complat/react-spectra-editor",
-  "version": "1.8.0",
+  "version": "1.8.1",
   "description": "An editor to View and Edit Chemical Spectra data (NMR, IR, MS, CV, UIVIS, XRD, GC, and DSC).",
   "repository": {
     "type": "git",